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SMITHSONIAN INSTITUTION
UNITED STATES NATIONAL MUSEUM
ButieTin 169
-
THE FORT UNION OF THE
CRAZY MOUNTAIN FIELD, MONTANA
AND ITS MAMMALIAN FAUNAS
BY
GEORGE GAYLORD SIMPSON
American Museum of Natural History
New York City
“i
UNITED STATES
GOVERNMENT PRINTING OFFICE
WASHINGTON : 1937
For sale by the Superintendent of Documents, Washington, D.C. = - - - - - - - - - Price 45 cents
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Dedicated to the Memory of
James Williams Gidley, Ph. D.
1866-1931
ADVERTISEMENT
The scientific publications of the National Museum include two
series, known, respectively, as Proceedings and Bulletin.
The Proceedings series, begun in 1878, is intended primarily as a
medium for the publication of original papers, based on the collec-
tions of the National Museum, that set forth newly acquired facts
in biology, anthropology, and geology, with descriptions of new
forms and revisions of limited groups. Copies of each paper, in
pamphlet form, are distributed as published to libraries and scientific
organizations and to specialists and others interested in the different
subjects.
The dates at which these separate papers are published are recorded
in the table of contents of each of the volumes.
The Bulletin series, the first of which was issued in 1875, consists
of separate publications comprising monographs of large zoological
groups and other general systematic treatises (occasionally in several
volumes), faunal works, reports of expeditions, catalogs of type speci-
mens and special collections, and other material of similar nature.
The majority of the volumes are octavo in size, but a quarto size has
been adopted in a few instances in which large plates were regarded
as indispensable. In the Bulletin series appear volumes under the
heading Contributions from the United States National Herbarium, in
octavo form, published by the National Museum since 1902, which
contain papers relating to the botanical collections of the Museum.
The present volume forms No. 169 of the Bulletin series.
ALEXANDER WETMORE,
Assistant Secretary, Smithsonian Institution.
WasuinatTon, D. C,, June 16, 1987.
IV
Introduction
History
CONTENTS
of this study and acknowledgments___._-....------------.
IPTEVIOUS) WOLD KS: 22 oe eee ee a te ee ee ee
pannel Geology anu aumas a2 s2 28M 9 oon oe eee oe ace
Geomraia iy sane a ees ey EN a ae ect
Geology
DStratiprapliye oo ae 8 ee a ote ee ee Saas oa eae
Generaltstrationraphicexco lumi sis 2 ae ee re
Cretaceoussertiarystransltionesoa= se eee eee ee eee
TOT WTO eee ee ee 2 ey nt
SHUG Rs eT SR ee ee ee eee
Hossilslocalitiesvandstaunalelistsiess 5-6-2 ee ee eee
General'occurrence of fossilimammals=s___ == = = ee a=
The Gidley<and)Silberling: Quarries: 3252 22028 22 ee ss
ARoe Sree Ae Oh ae ee ee ee ee eee eae
Othermportant, localities. < .2c2. sao: ook eae ese
SenialelistromlOGAliGiess sas. — eo ets me ect sa pe a ea
Ind
ex tolocalities|by section numbers=— —-= 222 Se
Haunalsuecession and Gorrelatlones. 22 es es ee eee
Ecology
Notes on nonmammalian biota== 3-2 —=- ne a ee eee eee
Ma
OTH aa: Wea 2 Keo ets eer se i See ee eee ae eee
The Gidley Quarry and ecological incompatibility__------------
Extent of knowledge of Middle and Upper Paleocene faunas----
Part 2: Cla
ssification and description of mammals_---_-.-.-----------
Order Multituberculata, Cope. 2. --.2-56+ 222. 4-234 nae nena stom
Affi
nitiesior thes Multijuberculata=— 4) 295-22 e- eee ane
IMethods.of stud ysi=- 2 22 ape eye a tee eg oe ee
amily Ptilodontidae Simpson: —-- 3-25-25 ee on ae ae
Key to American genera of Tertiary Ptilodontidae__-_-----
Comparison: of species 42432226 = 2 2 ee oe
Genus Pitlodus* Cope. 222.2286 5 Se ee eee
Genus Ectypodus Matthew and Granger-_-..--------------
Genus Pareetypodus Jepsen. = - == 2-2 4-5 a =
Genus Hucosmodon Matthew and Granger----------------
Orcersimsce uvOrsr GLa ys Sas og re ee ee
Family ?Deltatheridiidae Gregory and Simpson_---------------
8
ubfamily Didelphodontinae Matthew---------------------
Genus Géelastops Simpson. ..3 <5 2% 24 ot ee ee ae
Ramiy Deptictidac-Gill. 9.2.2 2a ee ce
Genus. Prodtacodon Matthew. ==" .2 5.22 —<<2-——-6—--—-=5--
Genus Leptacodon Matthew and Granger__---------------
Genus Myrmecoboides Gidley_...-2===---.2--= 5-<---=---
VI BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Part 2: Classification and description of mammals—Continued.
Order Insectivora Gray—Continued.
Family Nyctitheriidac Simpson=.-—-==-->-5=2-5---g--—-2----
Genus Sitipnodon Simpson. 2 <- {5552-22 eee eee
amily Pantolestidae: Cope 2222220 Us Sao a ee et ee
Pantolestinae, new sublamily== 2 22282 22-5 ance
Genus: Béessoecetor Simpson@2--— = — ae eee = eee eee
Pentacodontinae; ‘new subfamily2--- 22-222. -22222225252 2 2
Genus Aphronorus Simpsons 2.222522 5--eee eee es
Family Mixodectidse Coopers 2a- 2 ance ee eee eee
Genus Hudaemonema Simpsons -~ Ss. eae
Genus Eipidophorus Simpson-— 2-22 = So aa eee
TINSECTLV.OTa, in CCrtAe SECISse sao em ao ne ae ee a ee eee
Picrodontidaes newramily= saa ee a es
Genus*Picrodus Douglass= =. -- -- =e re ere ee
Family uncertaims<225s5 52. Soe a eee saosaeea
Genus"and species‘ undetermined2=:22- =~ 222 eS Se
Order serimates Linnaeus 22252 Sa soe es ee Se ee ee
Family 7Anaptomorphidae Copes2=4--22 25-5. ee ee ae eee ee
Genustearomomys Gidley: 2322 soe se eee eee ee
Genus and species undetermined-_-___..-..--.=-._-----..
Genus*Palaechihon: Gidley <2 eos ee ee ee
Genus Palenochiha simpsonso-2s2"--s2ee.- eee oe ee ee
Family Carpolestidae:pimpson 22> - ee ee eee
Genns Zl pnedotarsius Gidley = 22-225 22a ee eee
Family “Plesiadapidae Trovuessart. jo252. 22 0el se eee
Genus: Pronothodectes Gidley 2~ J22222 Soe S2 2-3 eee
Genus?Plestadapis Gervais 2-2 ee
Order, Faeniodonta! Cope. 22 an tee et eet eee eee eee eee
Family Stylinodontidac: Marsh22—- 2 2 ee 2 ee ee
Subfamily Conoryctinae Matthew_-—..-_----..----.--------
Genus: Conoryctes| Copes= 328 a oe ar ee ee eee
Psittacotheriinae. Matthew oo 2222-22-82 See a ee eee
Genus: siiacothersum: Cope 2. ao a ee ee nee
Order Carnivora Vieq:d’Azyro2 =o 2b Se ea ee eee
suborder Creodonta; Cope: 5-2 eee see se cece ee eee eee
Family Arctocy onidae Murray... ano een oe eee
Subfamily Arctocyoninsae Giebelo_ =. == aie a eee
Genus Ciaenodon Scottue 2282-0 eee ek eee
Genus Deuterogonodon Simpsonis- 22-222 sees eee
Subfamily Oxyclaeninae Matthew- 2-22 eee es _
Genus “Prothrypiacodon' Simpson eo -aaeeee see eee eee eee
Genus 'Chriatus’Copes] 25 ese ee ae ee ee
Genus Metachrtacus Simpson 3} —- oan eee eee eee
Genus Spernoryodon Simpson. 2 owe beens SUE ee ee
Mamotricentes: Tew @enuse 22 2 ae ee eee ee
Family: Miacidae"Cope {2 2) S222. oe een, Donen. s 2 en
Subfamily Viverravinae Matthew 22-22-0822 2 2 Lee ee
Genus: Didymictiis Copess ee a eo ee
Genus Ictidopaypus Simpsoni 2222s eee eee eee
Family Mesonychidae ‘Cope ss 2 as Bee SOLE Je
Genus “Dissacus* Cope 42 2a fe eee nee ee eee ee
CONTENTS
Part 2: Classification and description of mammals—Continued.
Order Cond yiartnranCopes=-— cso eae a See as See
Family Hyopsodontidae: Lydekker-.--...-.-...-...-<--=-+.--
Subfamily Mioclaeninae Matthew---.--.-------------------
Choeroclaenus Newekenuss== 23a = ee eee ee eee eee
Genlshhlinsodon SCOvvese ome nn a oS ose esa oe es
Genus bg aletes Sin psOn se a a ee occas
Subfamily Hyopsodontinae Trouessart__-------------------
Gaenuss 2iomiulius Simpsons. 8 2 oth ts oa eee
GenusvHanlatetes: Simpson = a nt So a oo aes
Family Phenacodontidae Cope 5. co---2 32e = ae wee
Genus Neiracitenodon Scout. =. 2256 = = ot oem
Genus Gidleyina:Simpsons=- -< =.= +---2:--2-----5s—
Hamily Peripiychidse Cope. - 2.2 sao St oss eet aeons
Subfamily Anisonchinae Osborn and Earle_-----------------
Genus: Cert phagus, Doupglass= 2. 2. 52s eet meee ae
Genus Antsonchus, COpe=s22_ <= 3052S o oe
Orden BantodontasCope: 2.662 oe eee ne hoe ee toe ina
Hamily, Pantolambdidse, Cope... -—-- =. + ss oso oaa Se
Genus, Pantolambaa Cone. ss. en ee
Pantolambda or allied genera, species undetermined _~------
RG tRereL LUPE CULOG Aire ot Sa lee a ee eo ote te
ILLUSTRATIONS
FIGURES
. Diagram showing the relative abundance of identified individuals of
the various orders and families of mammals in the National Museum
collection: fromthe: Gidleys#@uarrys2 se" Sees eee ee ee
. Comparison of relative abundance of families of mammals at various
localities in the Crazy Mountain Field, Mont__-_..--------------
Histograms illustrating Cabrera’s law as applied to the Gidley Quarry
. Histogram of measurements of second lower molars of all Lebo speci-
IMECTHISFOLM LCLOCHTCACUS Bae ae a ae a ee oer a ane eee
. Histograms of typical variates of multituberculates from the Gidley
ang silperlingOQuarmicst a5 52 232 ee ee ae ee ee eee
. Histogram and corresponding roughly fitted normal curve of length of
P, in Ptilodus montanus from the Gidley and Silberling Quarries-_---
. Scatter diagram of length of M; and length of P, for all Gidley and
Silberling Quarry specimens of multituberculates that show both
oftthese:measurementsM ae aes eo. 2 en a ee ee ee ee
. Left lower jaw of Ptilodus montanus Douglass_—-..--.--------------
. Lower dentitions of Ptilodus douglassi Simpson, P. gidleyt Simpson, and
IPEStNCLE1ITTESIM PON sees a ee Se ee eee ae ee eee eee
. Lower dentitions of Ectypodus grangeri Simpson, EH. russelli Simpson,
E. silberlingi Simpson, and Parectypodus jepsent Simpson__--------
. Part of lower incisor and fragment of jaw of Hucosmodon sparsus Simpson-
» Right lower jaw of Gelastops porcus Simpson-—-5---2--=2--22e5-25=—
. Right lower teeth and alveoli and right lower jaw of Gelastops parcus
SOTINT SOAS es ae oer eee per ns ee ee
. Left lower jaw of Prodiacodon concordiarcensis Simpson-------------
. Right lower jaw of Leptacodon ladae Simpson-__--------------------
. Left lower jaw of Leptacodon munusculum Simpson_----------------
. Left lower jaw of Myrmecoboides montanensis Gidley__..------------
. Right upper P!-M3 of Myrmecoboides montanensis Gidley__----------
. Left lower jaw of Stilpnodon simplicidens Simpson__..--------------
. Left lower jaw of Bessoecetor diluculi Simpson_...--.--------------
. Left upper jaw of Bessoecetor diluculi Simpson__..--.-.-------------
. Left lower jaw of Aphronorus fraudator Simpson_-_.----------------
. Right lower jaw of Aphronorus fraudator Simpson..----------------
. Left upper jaw of Aphronorus fraudator Simpson___----------------
. Left lower jaw of Hudaemonema cuspidata Simpson_-_---------------
. Left upper molars of Hudaemonema cuspidata Simpson_-------------
. Left lower jaw of Elpidophorus minor Simpson-_--------------------
. Right lower jaw of Picrodus silberlingit Douglass. .-.---------------
. Humerus of an unidentified fossorial mammal-____-----------------
. Right lower jaw of Paromomys maturus Gidley__..-----------------
. Left upper jaw of Paromomys maturus Gidley_...------------------
. Left lower jaw of Paromomys depressidens Gidley_-----------------
. Left upper molars of Palenochtha minor (Gidley) -------------------
Vill
Page
60
60
66
66
74
100
103
110
110
112
113
113
118
118
119
122
123
123
125
125
132
132
134
137
140
150
150
154
160
ILLUSTRATIONS IX
Page
S450 Upper molar of Conoryctes comma Cope. _- <2. ~~ ---2=--=--2-=--- 169
35. Histogram of length of M2 of Claenodon from the Torrejon of New
Mexico,in, the American: Museums = 525-575 o-- 3 Sot uk oe 178
36. Tentatively referred specimens of Claenodon ferox (Cope) from the
Melville (Fort Union No. 3): Left Mg, right My, left M»-3 and heel of
Maarighibye stan dlehtyMcsen ke Ses res ee Se ee le 180
37. Skull and jaws, left side, of Claenodon montanensis (Gidley) ----------- 183
38. Skull of Claenodon montanensis (Gidley), palatal view__-..----------- 183
39. Foot bones of Claenodon montanensis (Gidley) ..-.------------------ 184
40. Left upper jaw of Claenodon silberlingi (Gidley) --------------------- 186
41. Right lower jaw of Claenodon latidens (Gidley) --------------------- 188
42. Left M2-3 of Claenodon vecordensis Simpson__..-.------------------ 189
A Samet MV nnOtee CLOCNOUONISD sate eee ay tet ee ee ee ee 189
44, Right M?-3 of Deuterogonodon montanus (Gidley) ------------------- 191
45. Right lower jaw of Prothryptacodon furens Simpson-_---------------- 196
46. Right lower jaw of Chriacus pugnaz Simpson_—----------------=---- 196
47. Left Mi-3 of Metachriacus punitor Simpson_-_-_--------------------- 198
48. Right lower jaw of Metachriacus punitor Simpson------------------ 198
49. Weft M'>* of Metachriacus, punitor Simpson. = --———_ =. = 198
50. Left lower jaw of Metachriacus provocator Simpson----------------- 202
51. Left M2-3 of Metachriacus provocator Simpson-_--_------------------- 202
52. Left M!— of Metachriacus provocator Simpson..------~------------- 202
53. Left lower jaw of Spanozyodon latrunculus Simpson-_---------------- 204
54. Left lower jaw of Mimotricentes latidens (Gidley) ---_--------------- 204
55. Left lower jaw of Mimotricentes angustidens Simpson-_-------------- 206
56. Left lower jaw of Didymictis microlestes Simpson------------------- 211
57. Left P?-M?2 of Didymictis microlestes Simpson -....----------------- 211
58a duett lower jaw of Didymictis tenuts Simpson 222. - 2225-25-22 225552- 212
59. Referred specimens of Didymictis haydenianus Cope from the Lebo:
Left upper jaw with carnassial and right upper carnassial_______---- 213
60. Right lower jaw of Ictidopappus mustelinus Simpson-_-_--------------- 214
61. Left upper jaw of Ictidopappus mustelinus Simpson------------------ 214
62. Right lower jaw of Hilipsodon aquilonius Simpson------------------ 235
63. Left upper jaw of Ellipsodon aquilonius Simpson-_-_----------------- 235
64. Right Ps-Ms3 and right lower jaws of Litaletes disjunctus Simpson----- 240
65. Right upper jaw of Litaletes disjunctus Simpson----------- Bi ae dee 240
66. Left lower jaw of Litomylus dissentaneus Simpson ------------------ 242
67. Right M'-3 of Litomylus dissentaneus Simpson--------------------- 242
68. Right lower jaw of Haplaletes disceptatrix Simpson_---------------- 244
69. Right upper jaw of Haplaletes disceptatrix Simpson-_-_--------------- 244
70. Right lower jaw (with M;) of Tetraclaenodon symbolicus Gidley - ------- 247
71. Right Mi-,and right M?-3 of Tetraclaenodon symbolicus Gidley ------ -- 247
72. Left upper jaw of Gidleyina montanensis (Gidley) ------------------ 252
73. Left lower jaw of ?Gidleyina silberlingi (Gidley) .------------------- 254
74. Left lower jaw of ?Gidleyina superior (Simpson) -------------------- 255
75. Left lower jaw of Coriphagus montanus Douglass--_----------------- 260
76. Left upper jaw of Coriphagus montanus Douglass_------------------ 261
77. Right lower jaw of referred specimen of Anisonchus sectorius (Cope)
fromunesWebOsea = see 8 fae eke ae ee a= ae ee eae eS 261
78. Right upper jaw of referred specimen of Anisonchus sectorius (Cope)
franc aesepotams eee eS Ne BP oe Sse ee nos 261
79. Histogram of length of M; in Anisonchus sectorius (Cope): Torrejon
andelebospecimens. 252504 0522 cans Soa ee eset eee ste obec se 263
80. Right lower jaw of Pantolambda intermedius Simpson---------------- 270
Hm CO bo
10.
BULLETIN 169, UNITED STATES NATIONAL MUSEUM
PLATES
Following
. Reconnaissance map of the mammal-bearing Fort Union group of the
Crazy Mountain Field, Wheatland and Sweetgrass Counties, Mont - -
. Bear and Lebo formations, Crazy Mountain Field, Mont__------_-_--
. Air views of Fort Union group, Crazy Mountain Field, Mont_--------
. Air views of Gidley Quarry, Fort Union group, Crazy Mountain Field,
. Air view and site of the Silberling Quarry, Fort Union group, Crazy
IMO um bari ie) eI ra Ge a creas ee epee ee ee rn
. Melville formation, Crazy Mountain Field, Mont_-_--.-_------------
. Fort Union primates: Palaechthon alticuspis Gidley and Paromomys
mauris Gidley, richt lower jawsies 2622-5 22 aaane ee ee
. Fort Union primates: Pronothodectes matthewi Gidley and Paromomys
maturus Gidley Meitlower IaWSsno2 scones o seach eee ee ee eee
Fort Union primates: Plesiadapis gidleyi (Matthew), Pronothodectes
matthewi Gidley, Plesiadapis rex (Gidley), Palaechthon alticuspis
Gidley, Paromomys depressidens Gidley, and undetermined species,
(GE3 0H GFK) 0 Weapere che eels Doel erties Ea A 8 eR mete a ee SPE a
Fort Union primates: Palenochtha minor (Gidley), Elphidotarsius
florencae Gidley, and Pronothodectes matthewi Gidley, lower jaws-----
page
THE FORT UNION OF THE CRAZY MOUNTAIN
FIELD, MONTANA, AND ITS MAMMALIAN
FAUNAS
By Grorce GayLorp Simpson
American Museum of Natural History, New York City
INTRODUCTION
Tu1s work is chiefly devoted to the description and discussion of
a large collection of Paleocene mammals, from the Fort Union of
central Montana, belonging to the United States National Museum.
The first part of the memoir is geological, chiefly stratigraphic and
paleontological. The location and general characteristics of the
mammal-bearing area are described, followed by a résumé of its
stratigraphy and geologic Structure. The general areal geology is
only briefly outlined, and details are largely confined to the beds in
which the mammals occur. In the paleontological section, the various
fossil localities are listed, and the mammalian fauna of each is given,
together with a summary of all fossil mammals found in the field.
Faunal succession and faunal correlation, supplementing the remarks
made in the previous section on more purely stratigraphic correlation,
are discussed in detail. The general aspect and ecologic relation-
ships of the mammalian faunas are also discussed. Nonmammalian
fossils are incidentally mentioned, without any attempt at exhaustive
treatment.
The second and longer part of the memoir is zoological and is
devoted to definitions of all taxonomic groups which were originally
described from this field or the conception of which is markedly
affected by material from here, to discussion of the relationships
and phylogeny of the mammals represented, and to description of
the specimens in the collection.
Geology outside the area of reference and mammals other than
those definitely identified here are mentioned only for the sake of
comparison.
In addition to the National Museum collection, specimens from
this field now at Princeton University are included. Reference is
also made to a small collection in the Carnegie Museum, but since
this includes nothing not better represented in the National Museum
collection, none of it is treated in detail. Some, but not all, of a
large collection in the American Museum of Natural History from
1
2, BULLETIN 169, UNITED STATES NATIONAL MUSEUM
this same field is also mentioned or discussed. In a few cases classi-
fication has demanded some detail concerning fossils from other col-
lections and areas, especially the San Juan Basin, in New Mexico,
notably in dealing with the genera Claenodon and Anisonchus.
Most of the new genera and species recognized in the course of
this work were named, with brief diagnoses, in a preliminary note
abstracted from the first draft of part 2 (Simpson, 1935d). These
diagnoses are here repeated, in some cases in emended form, and ac-
companied by the extended discussion and description omitted in the
preliminary paper. There is included a full discussion of the fossil
Primates, even though these have already been published in some
detail (Gidley, 1923).
In the course of preparation of this bulletin, I have had access
to and have made constant use of a memoir on the Paleocene of the
San Juan Basin by the late Dr. W. D. Matthew. This has now
been published by the American Philosophical Society, but it was
available only in manuscript throughout the course of my work.
Reference to it is made by the citation ‘“(Pale. Mem.).” Other
citations are by author and year and refer to the ‘Literature cited”
at the end. As far as possible without destroying the comprehensive
and unified character of this work, I have avoided any duplication
of material contained in Matthew’s memoir. For groups that he
also discusses I have generally omitted diagnoses and have confined
discussion to a brief summary and to those points wherein I differ
from him.
Throughout this work, wherever they proved useful, statistical
methods have been employed. These are all summed up in Fisher
(1925) and also in a paper soon to be published (Simpson and Roe).
The methodology is outlined here in connection with the first group
treated, the Multituberculata. In all the statistical figures given,
the stated error is standard, not probable. The following abbrevi-
ations are consistently used throughout for brevity, along with the
universally understood symbols for teeth.
L= Length.
W = Width.
N=Number of specimens in a given sample.
R= Kange.
M= Mean.
o=Standard deviation.
d/o = Deviation from a specified mean, divided by the corresponding stand-
ard deviation.
V=Coeflicient of variability —<
P= Probability. } [as defined
t=A constant for comparing small samples lby Fisher.
=(d?) =Sum of the squares of deviations from the mean.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 3
In the systematic zoological part of this work, it has not seemed
necessary in each case to give the evidence or arguments for associa-
tions of upper and lower dentitions. With very few exceptions these
collocations are not based on actual association of upper and lower
jaw remains of one individual, which is very rare in this field. It is
based rather on occlusion, occurrence at the same localities, relative
abundance, comparison with related forms from other fields, and
similar indirect but usually conclusive criteria. In the few cases
where there is any serious doubt about the association, this fact is
mentioned.
This manuscript was completed on March 15, 1936. Slight changes:
have since been introduced, but no later general revision has been
made, and with few exceptions statements made are to be taken as
of that date.
HISTORY OF THIS STUDY AND ACKNOWLEDGMENTS
Work for this memoir was started in 1908, when Dr. T. W. Stanton
commissioned Albert C. Silberling to collect Fort Union fossils for
the United States Geological Survey and the United States National
Museum. In 1909 Dr. J. W. Gidley visited the field, where he di-
rected and planned further work by Silberling, and he also then under-
took the laboratory and office work on the collection. In view of
the extremely fragmentary and few fossil mammals that had been
collected in the Fort Union up to 1908 and the general scarcity of
mammals of comparable age from any formation, the magnitude to
which this work would grow could not have been anticipated when
it was started. In 1911, when Mr. Silberling finished his most inten-
sive work on this collection (to which he also added periodically until
1932), he had brought together one of the largest collections of Paleo-
cene mammals ever made. Furthermore, this collection consisted
almost entirely of new species, more than half the genera were new,
and it greatly extended morphological and distributional knowledge
of the families and orders represented. The collection represented,
potentially, the greatest single contribution to knowledge of early
mammals that had ever been made.
The very magnitude of the results achieved was embarrassing.
All these hundreds of specimens had to be prepared, the majority
of them by tediously working off the matrix grain by grain under a
microscope. Concurrently with many other duties, this was undertaken
by Dr. Gidley, and it occupied much of his time over a period of 12
years. Then the identification of the material presented great diffi-
culties, as it must in any Paleocene collection, for on one hand all the
genera and species are clearly variable and on the other the really
significant characters are often in such small details that it may be
difficult to distinguish forms properly classified in different orders.
4 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
These difficulties were enhanced by the fact that the most pertinent
comparative material was in another institution and that Dr. Gidley’s
other duties did not permit his spending the months, or even years,
of comparative study necessary under these circumstances, except by
short visits or the loan of a few specimens as opportunity presented.
In spite of the- really tremendous amount of work that he had
accomplished on the collection, Dr. Gidley was able to complete only
a relatively small part of the final preparation and publication of
manuscript before his death on September 26, 1931. Up to the end,
he looked forward to the completion of the work, and remarked, in
conversation, that the collection was the most important ever in his
hands and that its publication would be his greatest contribution to
science and his most enduring monument. This it is, despite the
fact that he was not spared to complete it with his own hands.
In 1932, Dr. Alexander Wetmore and C. W. Gilmore invited me to
undertake the completion of this study. The officers of the American
Museum of Natural History permitted the use of my time, as a coop-
erative undertaking with the United States National Museum. The
whole collection was shipped to New York, where it could be studied
under the best possible circumstances and compared at first hand with
almost all the other types of American Paleocene mammals. Knowl-
edge of the field, and further accessions to the collections, were made
possible by work with Mr. Silberling in Montana for the National
Museum in 1932 and for the American Museum in 1935.
The great extent of Dr. Gidley’s contribution to this work should
be explicitly stated.! In the first place, the existence of this splendid
collection is in large part due to him. He collected some of the best
material, and he directed and encouraged the collection of most of it.
Second, he prepared and cataloged the whole collection so that it
came to me in almost perfect condition for immediate study. Third,
he prepared and published four preliminary papers (as listed in the
bibliography and discussed in the proper places in the text). It is
inevitable that some differences in point of view and more particularly
the lapse of time make complete agreement impossible, but his pre-
liminary work greatly facilitated study of the groups involved.
Fourth, a number of unpublished illustrations had been prepared
under Dr. Gidley’s direction, and most of them appear in this publi-
cation. Finally, he left a few notes on the unpublished parts of the
collection.
There is reason to believe that Dr. Gidley had the major outlines
of the classification of the collection, and probably also many of its
details, wellin mind. This preliminary orientation is one of the long-
est and most difficult parts of research, but unfortunately Dr. Gidley
did not find it necessary for his own use to reduce it to writing and
1 For a review of Dr. Gidley’s life and work see Lull (1932).
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 5
could not foresee how important this would have been for his suc-
cessors. The available notes are thus fewer and less useful than was
anticipated. Specifically, they are as follows:
1. A field notebook containing a list of 43 specimens collected by
Gidley, with locality, horizon, and date, but no other data.
2. Illustrations and proofs of his paper on the Primates, with no
unpublished data.
3. Notes on multituberculates and claenodonts, with no unpublished
observations.
4. Twenty-seven pages of notes and of manuscript in various stages
of preparation, with considerable duplication and different drafts of
treatments of the same subject. These, the only unpublished original
observations left by Dr. Gidley, include brief preliminary diagnoses of
three new species of Tetraclaenodon, one of Protogonodon, one of Mio-
claenus, one of Tricentes, one of Mixodectes, and one of a genus probably
considered as new but not named or defined, and also a sketch diag-
nosis of a new genus and species of phenacodonts (here called Gidleyina
montanensis).
As far as they can be deduced from these notes, I have mentioned
Dr. Gidley’s opinions in the present text. In some cases they warrant
detailed discussion and quotation. In others, his notes were clearly
of the most preliminary sort and would surely have been modified
before publication, and in these cases it has seemed unjust to do more
than mention them briefly. As regards the recognition of species,
I first studied the collection independently and then ascertained
whether any new species (or genera) recognized by me were antici-
pated in Dr. Gidley’s notes. If they were, I credited them to Gidley,
ex ms.”, and quoted sufficient of his diagnosis to establish his author-
ship. The species so recognized are Deuterogonodon montanus, Mimo-
tricentes latidens, Tetraclaenodon symbolicus, and Gidleyina montanen-
sis. Dr. Gidley’s notes also include diagnosis of the genus Gidleyina
but under a preoccupied name.
Some other new forms are recognized in the notes, but without a
name or without a diagnosis or definite indication, so that Dr. Gidley
could not technically be established as their author, but his recognition
of them is mentioned. In a few cases I have been unable to agree that
a form tentatively designated as new by Dr. Gidley is so, and then have
pointed out this fact but have omitted his names in order not to create
useless synonymy.
None of Dr. Gidley’s notes were in such shape that it would have
been just to him to publish them without revision, and in any event
only a small part of this memoir is affected by his unpublished notes.
"Gioue tatarnntional Rules of Zoological Nomenclature, Article 21, state that the author ofa scientific name
is he who first publishes it with a valid definition ‘‘unless it is clear from the contents of the publication that
some other person is responsible for said name and its indication, definition, or description.’”’ This validates
Gidley’s authorship of these species published by me.
6 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
That this work has been written at all is largely due to Dr. Gidley, but
he is not responsible for its errors or for any matter in it not explicitly
stated to be his.
It is further desired to acknowledge how much this work owes to
Albert C. Silberling, whose contributions to it go far beyond those
usual from a collector. He discovered most of the fossil localities,
including all those of real importance, and made far the greatest part
of the collection, with skill, persistence, and devotion that cannot be
too highly praised. He established a system of field records of the
greatest accuracy, used throughout this publication. Even beyond
this he so thoroughly examined the field and so carefully studied and
correctly interpreted its geology that much of what is here written
about it, and of what has appeared in publications by others, is merely
reducing to writing observations made by or with him. Heis thusina
sense an author and authority of the geologic part of this work,
although he has not actually written any of it and is not responsible for
misinterpretation of his views or observations. Aside from the long
periods when he was definitely employed as a collector, Mr. Silberling
has spent every spare moment for the past 35 years working in this
field, and this memoir is in a real sense the outcome of this lifetime
vocation and avocation.
The following illustrations were drawn by Rudolph Weber under
Dr. Gidley’s direction: Figures 22, 30-34, 37-41, 44b and b’, 59, 63a,
71a and a’, 72, 736, 80.2 The other drawings were made by Sydney
Prentice, under my direction. The accompanying map is based on
field work by Silberling and me and was drawn by John C. Germann.
The field photographs were taken by me.
The late Prof. W. J. Sinclair, of Princeton University, lent and per-
mitted the description of the specimens collected for that institution
by Douglass and by parties under Farr. Dr. G. L. Jepsen has facili-
tated comparisons with specimens collected under his leadership for
Princeton in the Fort Union of Wyoming. The Carnegie Museum,
through J. J. Burke, lent material in their collection from this field.
I am much indebted to these institutions and colleagues, as well as to
officials of the United States National Museum, particularly Dr. Wet-
more and Mr. Gilmore, for their support of the work and constant aid
and encouragement, and of the American Museum of Natural History
for the time and facilities provided.
PREVIOUS WORK
Discovery of Paleocene* mammals lagged behind that of typical
faunas of any later epoch, or even of the Mesozoic. This slowness of
discovery and the factors of scarcity of fossils and difficulties of study
3 In a few cases Prentice has modified these drawings slightly.
«“Paleocene” is granted to be an epoch of the Tertiary, including post-Lance or post-Danian and pre-
Gray Bull or pre-Sparnacian time.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 7
to which it was due have made the subject of Paleocene mammals an
obscure one, generally avoided, but they have also made it a particu-
larly fruitful field for research in recent years.
The first Paleocene mammalian fauna to be discovered was that of
the Thanetian, or particularly of its subdivision the Cernaysian, in
France. Arctocyon primaevus was described by Blainville in 1841, but
knowledge of the fauna really dates from Lemoine’s publications
beginning in 1878. It has only recently been revised and placed on a
satisfactory basis by Teilhard (1916, 1921).
The American Puerco formation of New Mexico was named in
1875 but yielded no mammals until 1881, when the famous collector
David Baldwin began a long collecting campaign there for Cope. This
work has been followed, since 1892, by a series of expeditions to this
field under Wortman, Granger, Sinclair, Simpson, and others for the
American Museum of Natural History, which also acquired the Cope-
Baldwin collection. This stratigraphic sequence in the San Juan
Basin of New Mexico has become the standard of comparison for the
Paleocene of the world, and its faunas are far the best known and
represented by the most nearly perfect specimens (although in variety
they do not exceed those to be described in this memoir). They have
been described by Cope, Osborn, Earle, Wortman, Matthew, Granger,
Simpson, and others and are thoroughly revised in a memoir by
Matthew (Pale. Mem.), published while this bulletin was in press.
Three quite distinct formations and faunas have been recognized,
Puerco, Torrejon, and Tiffany, the first two each with two well-marked
separate faunal zones of different facies but nearly the same age.
The Fort Union group was originally defined by Meek and Hayden
(1861) as occupying “‘the country around Fort Union,® extending north
into the British possessions to unknown distances; also southward to
Fort Clark. . . . Seen under the White River group on North Platte
River above Fort Laramie. Also on west side of the Wind River
Mountains. . . . and also occupying extensive areas of country in
Nebraska . . . and beneath the White River group at several distant
localities.” Although the designation of the type locality leaves no
doubt as to the inclusion of certain strata in the group or as to its
general position in the scale, the name has been used in many different
ways, and in keeping with the spirit of the original description it has
been applied to any or all strata at about this part of the geologic
section, that is, in what we now call Paleocene, over a very large area
in the Northwest. Thanks to this widespread occurrence or use of the
name, and to the economic value of these rocks, especially as a coal-
bearing series, few geologic formations have been more intensively and
extensively studied. No general review of this work is here attempted
5 Near the present site of Buford, N. Dak.
11921237
9
_
8 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
(see résumé and references in Thom and Dobbin, 1924) aside from the
Crazy Mountain area and briefer mention of mammal discoveries
elsewhere.
The earliest geological work in the particular area here under dis-
cussion appears to be that of W. H. Weed. In 1893 he mentioned the
presence of about 4,000 feet of Fort Union sediments overlying his
Livingston formation east of the Crazy Mountains. In the Livingston
(Weed, 1894) and Little Belt Mountains (Weed, 1899) folios, he in-
cluded the extreme western part of this area and referred to the
presence of Fort Union here but mapped it all as Livingston. In an
article on the Fort Union (Weed, 1896) he also discussed the Fort
Union area in a general way and gave a section of part of these and of
lower beds along Lebo Creek.
The first more detailed consideration of this area and the first ade-
quate reference to its more important northeastern part was by Earl
Douglass. In 1900 he worked here, principally in the Cretaceous but
also in the Fort Union, where he collected leaves and invertebrates.
In 1901 a Princeton University expedition was sent out under Dr.
M.S. Farr, and Douglass accompanied this party and also continued
work after they had left. The Princeton party traversed the Fort
Union exposures, but most of their work of that season was in the
Cretaceous. In August 1901, Douglass found the first mammals in
this field, and the first ever discovered in the Fort Union, at two
localities (5 and 6 of the lists given on a later page) near the northern
end of Bear Butte. Although fragmentary and few, these sufficed to
show the equivalence of these beds to the Torrejon of New Mexico
(Douglass, 1902a). Douglass soon published detailed descriptions of
the mammals and a discussion of the geology of the whole area (Doug-
lass, 1902b). The Princeton party was also accompanied by Albert
Silberling, then a boy of 16, who was destined to play the major role
in the development of this field.
Princeton field parties, also under Dr. Farr and accompanied by
Silberling, revisited the area in 1902 and 1903, and they then examined
the Fort Union in more detail and found fossil mammals at a number
of scattered localities and at widely different levels, from near the base
of the formation to about 4,350 feet above the base and from the
northeastern part of the field to the vicinity of Cayuse Butte, near the
western margin of the principal mammal-bearing area. The fossils
collected and observations made in 1902 and 1903 have never been
published.
In 1905 Douglass made a long reconnaissance through Montana,
and in the course of this he went northward from Bigtimber to Cayuse
(or Melville) Butte. He noted the presence of the Fort Union over
much of this traverse but did not add significantly to exact knowledge
of the field. Apparently he had not been informed of the unpublished
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 9
discoveries of 1902 and 1903 on and around Cayuse Butte, and he
found no mammals on his brief visit. His account of this trip (Doug-
lass, 1909) includes a résumé of the geology of the area, involving also
his observations in 1900 and 1901.
In the meantime Silberling had continued prospecting the field and
had located the two richest known deposits, later developed as the
Silberling and Gidley Quarries. He was for a time associated with the
Carnegie Museum, to which Douglass had now also gone, and he sent
in to it a small but important collection, principally from the Silberling
Quarry. This was described by Douglass a few years later (Douglass,
1908) and was the basis of the first exact definition of mammals from
this field, including the types of Ptilodus montanus, Picrodus silber-
lingi, Coriphagus montanus, and Megopterna minuta,’ as well as many
less exactly identifiable specimens.
In 1907 (see Stone, 1909) R. W. Stone worked in the northern part
of this area for the United States Geological Survey, and in 1908
W. R. Calvert worked south of the area. They connected their ob-
servations west of the Crazy Mountains, and in 1909 also by recon-
naissance east of the mountains and later published an important
discussion of the Fort Union here and of its relations to the Livingston,
applying the name Lebo to the lower part of the Fort Union (Stone
and Calvert, 1910).
In 1908 Dr. T. W. Stanton visited the field, where he was accom-
panied by Silberling, who had in the meantime left the Carnegie
Museum and started ranching in this area. They made detailed
observations, including a section of the Lebo which I give on a later
page, and Silberling was employed under Stanton’s direction to collect
for the United States Geological Survey and National Museum
(Stanton, 1909). Knowlton had taken some interest in observations
here, principally in connection with his placing of the Hell Creek and
synchronous beds in the ‘Lower Fort Union” (see Knowlton, 1909),
a view now universally abandoned and requiring no consideration
here. In 1909, Stanton, Stone, Calvert, Knowlton, and M. R.
Campbell briefly visited the area again to check certain critical
localities, the results of their observations being principally given by
Stone and Calvert (1910). Stanton (1914) and Knowlton (1914)
later returned to their argument regarding the Cretaceous—Tertiary
boundary, but with only incidental reference to this area.
Silberling continued the collecting begun in 1908 and spent much
time in 1909, 1910, and 1911 collecting for the National Museum.
It was in these years that he obtained most of the specimens described
in this work. A few specimens collected in later years were also
acquired by the National Museum, and Silberling has continually
spent much time in the field, even when not commissioned by any
6 Which is, however, invalid.
10 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
particular institution. In 1908 he had worked principally in the
Silberling Quarry. In 1909 Gidley visited the field and then opened
the Gidley Quarry at a site, Loc. 4, previously discovered by Silberling.
Gidley himself collected many fine specimens here, and the work was
continued by Silberling in 1909-11, and later, along with repeated
prospecting of surface localities. In 1911 Gidley made another visit
to the field.’
In 1909 Gidley described the splendid skull, jaws, and partial skele-
ton of Ptilodus that had been found in 1908 by Silberling in the Silber-
ling Quarry. This is still the best multituberculate specimen in any
museum, and the best single mammal specimen ever found in this
field. Gidley continued the preparation of the collection, work done
entirely by himself, as time and other duties permitted. This was
completed in 1920. In the meantime two preliminary papers had been
published, one on A/yrmecoboides (Gidley, 1915) and one on the clae-
nodonts (Gidley, 1919). After the whole collection was prepared he
began monographing it, but only the section on the Primates (Gidley,
1923) was completed or published. The extent of his unpublished
work has already been noted.
In 1930 Silberling made a renewed examination of the field and also
reopened the Gidley Quarry and made a collection that was purchased
by the American Museum. In 1932, under the auspices of the Na-
tional Museum (with the donation of my services by the American
Museum), Silberling and I went over the whole area and adjacent
regions, with the present work in mind. We then made the map
(pl. 1) that accompanies this memoir and also made detailed strati-
eraphic observations. A small amount of material was collected,
incidental to our visits to all the fossil localities, but no intensive
collecting or quarrying was undertaken.
In 1935 the Third Scarritt Expedition of the American Museum,
consisting of Mr. Silberling, a camp man, and me for the entire season,
and Mr. and Mrs. Fenley Hunter, Dr. Walter Granger, and Albert
Thomson for shorter periods, spent four months in this field, pros-
pecting most of the surface localities, reopening the Gidley and Silber-
ling Quarries, and developing a new quarry, named the Scarritt
Quarry. The resulting collection, about equal in size to that here
described, is in the American Museum. The material from the Scar-
ritt Quarry has been described (Simpson, 1936b), and the results are
here included in the general sections but not in the detailed descrip-
tions. The surface material, which is relatively abundant and im-
portant but does not include any species not also present in the
National Museum collection, has also been identified and is mentioned
where apropos in the present work. The very large Gidley Quarry
7 Gidley’s statement (1923, p. 1) that he visited the field in 1908 and 1909 is probably a misprint, for it is
contrary to Silberling’s memory and to letters and other records that seem to show that his visits were in
1909 and 1911.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 11
collection, and the few specimens from the Silberling Quarry, in the
American Museum are not yet studied and do not enter into this
study. For the most part they duplicate the collection described
here.
Of other mammal discoveries in the Fort Union, the first of any im-
portance was made by J. F. Lobdell in 1926 in a coal mine at Bear
Creek, Mont. Collections were later made here for the Carnegie
Museum and the American Museum and have been described by me
(Simpson, 1928a, 1929a, b). The small but interesting fauna is of
Upper Paleocene age, about equivalent to the Tiffany.
Discoveries in northern Wyoming, west of the Bighorn Mountains,
have been of outstanding value. Sinclair and Granger (1911, 1912;
also Granger, 1914) had found a fauna of Paleocene aspect here in
beds which had previously been considered to be true Eocene and
which they named Clark Fork. In 1927-29, Dr. G. L. Jepsen, work-
ing for Princeton University, found three distinct faunal horizons in
(nominal) Fort Union strata beneath the Clark Fork in this area.
He has shown that these correspond in age to the Puerco, Torrejon,
and Tiffany, and hence has for the first time established a definite
sequence of four distinguishable Paleocene mammalian faunas in a
single continuous stratigraphic section (Jepsen, 1930). The faunas
so far described are small but typical. Subsequent collecting under
Jepsen at the same localities has yielded much more and better
material, but the results have not yet been published.
Sporadic discoveries of one or two specimens have been made at a
few other Fort Union localities, but none is of much importance.
The type of Titanoides primaevus came from near the type locality of
the group, Buford, N. Dak. (Gidley, 1917). Typically Middle
Paleocene forms, Yetraclaenodon and Pantolambda, were found in
Billings County, N. Dak. (Lloyd and Hares, 1915). In Fort Union
or Kingsbury beds of the Bighorus a jaw identified by Gidley as
Tricentes was found (Stanton, 1909, p. 268). Eocene fossils were
found in supposed Fort Union beds in the Powder River Basin (Wege-
mann, 1917). The Jast-mentioned fossils, and perhaps that from the
Kingsbury, are not really from the Paleocene, or from true Fort
Union.
The Paskapoo of Alberta, which may be considered in a general
way a northern extension or equivalent of at least the upper part of
the Fort Union, has yielded a few mammals, the first found by Brown
in 1910 (Simpson, 1927), with later discoveries mostly by Russell
(1926, 1929, 1932), all extremely fragmentary. Recently Patterson,
working for the Field Museum of Natural History, collected fine skele-
tons of Barylambda, an ally of Titanoides, at an Upper Paleocene level
in the Plateau Valley formation of western Colorado (Patterson, 1933,
1934, 1935, 1937).
PART 1: GEOLOGY AND FAUNAS
GEOGRAPHY
The region here primarily considered is comprised in Tps. 3-6 N.
and Rs. 13-16 E. (Montana principal meridian), an area of about 575
square miles. It is approximately included in latitude 45°55’ to 46°20’
N., longitude 109°40’ to 110°10’ W., and is in central Montana,
Tps. 3-5 N. in Sweetgrass County and T. 6 N. in Wheatland County.
The principal commercial center is Harlowton, seat of Wheatland
County, 8 miles due north of the designated area. This town, popula-
tion about 1,500, is on the north side of the Musselshell River and is a
division point on the main line of the Chicago, Milwaukee, St. Paul,
and Pacific Railroad. About an equal distance south of the area is
Bigtimber, population 1,200, on the south bank of the Yellowstone
River. The only settlement in the limited region here primarily
treated is Melville, an old town once of some importance but now
reduced to little more than a post office and crossroads store. It is in
secs. 1l and 14, T.4 N., R. 14 E.
There are main east-west motor highways and railroads in the
Musselshell and Yellowstone Valleys, north and south of this area,
but just here east and west through travel is blocked by the impassable
mountains immediately to the west. There is, however, a secondary
north-south highway from Harlowton to Bigtimber through the area,
and this is now being improved and graveled (1935). There are
several county roads, graded but unsurfaced, as shown on the map,
and also many private roads and wagon trails, which permit approach
to within a mile or less of any point in the field.
Much of the land has been plowed for dry-land wheat raising, but
a great deal of it was not suitable for this purpose and so most of the
wheat farms have been abandoned. A little wheat and some hay or
alfalfa are still raised, but most of the region is given over to grazing,
mainly as winter range for sheep and some cattle. The population is
sparse and in recent years has not been prosperous. There are a few
dude ranches in and near the mountains in the western part of the
field. There are no known mineral resources.
Topographically the area lies immediately east of the Crazy Moun-
tains, a very rugged and beautiful isolated range 25 or 30 miles long,
north to south, and 10 to 15 miles in width, rising to 11,178 feet in
Crazy. Peak. The area specifically treated extends from the foothills
of the mountains eastward about 25 miles. The divide between the
Musselshell and Yellowstone Rivers runs through the field. The
northern part is drained mostly by Fish Creek, here running eastward,
12
21AWN0I39
ES SE pees See = 1
PORCUPINE BUTTE
RISE
TO BIG ELK CR
EEK
SECTION ALONG LINE
R.I4E R.ASE
| TO HARLOWTON
— =
Ay 1B: SCALE
tg2000
Eioee
° 1 2
(Horizontal and Ve i
ELEVATION
WHEATLAND CO. bee
a aa co.
iat
a
43342
RISE
3
SCALE IN MILES
at
TO BIGTIMBER
RI4E
RISE
RECONNAISSANCE MAP OF THE MAMMAL BEARING
FORT UNION GROUP
OF THE
CRAZY MOUNTAIN FIELD
WHEATLAND AND SWEETGRASS COUNTIES
MONTANA
XX MAMMAL LOCALITY
FORMATION CONTACTS
eae ¢ wi singer ug
: CRAZY MOUNTAIN. FIELD ue
— AWD oon orale COUNTIES |
; _—r ne _
——
/
Z
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 13
and its southern part mostly by Sweetgrass and Otter Creeks and
their tributaries, here running mainly southeastward. The extreme
northwestern part is drained by American Fork and Lebo Creeks,
tributaries of the Musselshell, and the extreme southwestern part by
Bigtimber Creek, tributary to the Yellowstone. Lebo and Fish
Creeks rise in this area and carry little water in ordinary weather,
while the other streams mentioned rise in the mountains and have
larger and more nearly permanent flow.
Apart from the actual mountain area and its flanking zone of
pediments, moraines, and outwash, here poorly developed, this region
is a hilly one with mature topography almost entirely determined by
the hardness and structure of the underlying rocks. The harder
sandstones form ridges and scarps, and the softer beds are eroded into
valleys or flats. The most striking elevations in the northeastern
part of the field, like Bear Butte and Lion Butte, are sandstone-
capped erosion forms. Cayuse Butte, a prominent but relatively low
and irregular mass, and Porcupine Butte, the most prominent eleva-
tion outside the mountains, also are supported by intrusive igneous
rocks (as are the mountains). The southern part of the field is hilly
but has no prominent topographic features. There are three small lakes
in the area, Lebo Lake in the northwest and Lakes Adam and Wal-
voord (more generally known as the Glass Lindsay Lakes) in the
southeast, all artificial and developed for irrigation.
The highest point outside the mountains is Porcupine Butte, 6,970
feet, and the lowest is on Fish Creek where it leaves this area, about
4,000 feet.
Climate and vegetation vary from mountain to high-plains types.
The mountain flanks have forest of lodgepole pine and other conifers,
with aspens along the streams and some colorful meadows, while the
main part of the field is very sparsely timbered, with evergreens on the
higher sandstone ridges and cottonwoods in wet valley bottoms.
The broad intervening areas, except for the relatively small irrigated
patches, are characterized by sagebrush, pricklypears, small yuccas,
and grass. Abandoned plowed land is taken over by weeds, especially
Russian thistles. In spite of the rather sparse nature of the vegeta-
tion, almost the entire area is sodded over. Shale exposures are small
and relatively few, and there are no badlands.
The topography along the northern edge of the area (beyond the
Fort Union exposures) is very different, for here there are large, well-
developed, high, gravel-covered terraces cutting across the oes
Cretaceous beds without regard for their hardness. ag
This general Fort Union area has received various ae hole
such as ‘‘Fish Creek”’, ““Bear Butte’’, “Sweetgrass County”’, or ‘“‘Mel-
ville.” Fish Creek ie a minor stream draining less than half of the
region especially considered. Bear Butte is a small and marginal
14 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
topographic feature. Sweetgrass County does not include some of
the most important localities, and does include a vast area, much of
it south of the Yellowstone, far outside that here treated. Melville
is an unimportant settlement local to one small part of the field. This
whole region, a great synclinal area with Fort Union rocks filling it,
may be called the Crazy Mountain region, for these mountains occupy
its approximate center and are the most prominent topographic
feature in this part of the State, and the major structure has already
been called the Crazy Mountain Syncline. The smaller area desig-
nated and discussed above is, in general, the eastern half of the
Crazy Mountain region, and is that where the Crazy Mountain Fort
Union is best and most clearly developed and where it has yielded
mammals. This area will herein be called the Crazy Mountain Field.
GEOLOGY
STRATIGRAPHY
GENERAL STRATIGRAPHIC COLUMN
Rocks exposed in the area between the Musselshell and Yellowstone
Rivers and east of the Crazy Mountains are from Lower Cretaceous to
Recent in age. Aside from terrace gravels, moraine and outwash
deposits, valley fill, and other unconsolidated young deposits, not to be
considered here, the sedimentary rocks are Cretaceous and Paleocene,
as far as definitely established. ‘There are numerous igneous intru-
sions, all younger than the Paleocene sediments, and likewise omitted
from this discussion. The whole stratigraphic column, including
some rocks not exposed in the area of the map (pl. 1) but all within a
few miles of these and undoubtedly underlying this area, may be
summed up in a general way as shown in the column on page 15.
From exposures outside this area, especially in the Big Snowy and
Belt uplifts, it appears that the sedimentary rocks here exposed are
probably underlain by many thousands of feet of earlier Mesozoic,
Paleozoic, and pre-Cambrian sediments, probably one of the thickest
piles of sediments in the world.
The oldest surface beds of this region are exposed only in the centers
of domes north of the mapped area, for instance in sec. 34, T. 7 N., R.
16 EK. Dr. Barnum Brown has recently obtained some interesting
dinosaurs from this locality. ‘There is some question whether these
beds are closer to the Kootenai or to the approximately equivalent
Cloverley, but here they have generally been called Kootenai.
The series here called ‘Undifferentiated Colorado” is probably
susceptible to definite subdivision and correlation, but this has not
yet been clearly accomplished and is outside the scope of the present
study. The lower part was given the local name ‘‘American Fork”’ by
Douglass (1909), who called the upper, marine, beds ‘‘Fort Benton”’,
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 15
Dark shales, greenish or
No. 3 | Melville gray, with numerous gray | 5,000+ feet.
to yellow sandstones.
Mammals, ete.
Fort Soft somber greenish sandy
Union No. 2 shales and gray sand- | 850 feet.
stones. Mammals, ete.
Lebo rr
Somber shales with some
No. 1 hard brown sandstones. | 500 feet.
Mammals, etc.
euore Alternating pale cross-bed-
nion ded sandstones and shales.
(or Bear Rare turtle bones, ete. 500-600 feet.
Lance) No dinosaurs or mammals.
Pale, variegated clays with
Hell Creek some gray sandstone. Di- | 2,000 feet.
nosaurs.
Brown and yellow sandstone
and some somber shale.
Lennep Transitional marine-fresh- 250-450 feet.
water.
Soft dark shales. Marine.
Bearpaw (Also some dinosaurs.) 700-1,100 feet.
: Cross-bedded gray sand-
Judith River stone and sandy shale. | 400-800 feet.
Dinosaurs.
Brownish or yellowish thin-
bedded sandstones and
Claggett shales. Marine to brack- 400-800 feet.
ish invertebrates.
Three prominent coarse 100-250 feet.
Bogle white sandstones. Coal.
Upper part soft dark shales,
locally sandy. Lower
aloe part with much _ thin-
=o (Undifferentiated) bedded and ripple-marked | 1,300—2,000 feet.
sandstone. Upper part
marine, lower with dino-
saurs, turtles, and plants.
Variegated red, green, and
brown shales and sand-
Kootenai stones. Dinosaurs and | 200+ feet (base
5 D:¢ e
nonmarine mollusks. not exposed)
probably an inexact correlation. Probably equivalents of the Mowry,
Thermopolis, Frontier, and some other Wyoming formations are
included. A prominent but local sandstone member has been called
“Big Elk.”
Douglass at first (1902) called the overlying beds ‘‘Niobrara’’,
but their more exact correspondence with the Eagle and Claggett is
16 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
now wellestablished. In 1902 he applied the name “Fish Creek Beds”
to the next higher division but later accepted their equivalence to the
Judith River as established by Stanton and Hatcher (1905). Douglass
(1909) continued to use the name “Fish Creek” for beds transi-
tional between Judith River and Bearpaw, but this name is not now
in general use.
Lennep is a local name applied by Stone and Calvert to beds perhaps
equivalent to the Fox Hills but not definitely correlated. In physical
character they resemble the Lebo, and seem to gradeinto the Livingston
laterally.
CRETACEOUS—TERTIARY TRANSITION
It is not proposed to discuss here the general evidence for drawing
the boundary between the Cretaceous and the Tertiary, a problem to
which this field contributes only one small part, and not the most
important part. For present purposes it is assumed that beds up to
and including the true dinosaur-bearing Lance and Hell Creek and
their equivalents belong in the Cretaceous and that overlying beds
without dinosaurs (except by redeposition) and with mammals of
Tertiary type (including carnivores, condylarths, etc.), from the
Puerco and its equivalents upward, are to be placed in the Tertiary.
It is also assumed that the Paleocene is accepted as a separate epoch
of the Tertiary, of equal rank with the Eocene, Oligocene, Miocene, and
Pliocene, and that its lower limit is taken as the base of the Puerco
or equivalent, or the top of the (restricted) Lance or Hell Creek or
their equivalents, and its upper limit at the top of the Clark Fork, or
equivalent, or base of the Sand Coulee and Gray Bull, or equivalents.
On these assumptions, which I believe to be based on the most
reasonable and useful interpretation of all the evidence, it is here pro-
posed only to discuss briefly the beds in this field that must include
the transition from Cretaceous to Tertiary as thus defined and to
suggest where the boundary may occur in this local series.
The following is a somewhat generalized section from the Hell Creek
into the Fort Union No. 1 in sec. 26, T.6 N., R. 16 E., passing through
Loc. 65 and near Loc. 78, about 2 miles northeast of the northern
end of Bear Butte:
Soe a ce eee Hori zoniof@ioces (8). oan ee eee
Mostly greenish shales and sandy shales________-_---------- 30
Somber cross-bedded sandstone, the upper part bard and ridge-
Fort Rormmiinig 1S 8 ER IE ee CEE 40
Union Somber greenish shale and sandy shale____--- -------------- 85
No. 1. |Same, with bone fragments including unidentifiable mammals
of Mertiary aspect; boc: 652222 .2 25 Shee ees ae ee ee ee 7
name; withoubdossus 2-2. joe Pe a ee 35
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 17
Zone of hard brown concretions, with numerous fresh-water in-
vertebrates and some turtle bones___.___________-_-_---_-- +1
eee Transitional beds with shales somewhat darker than those below
and with local lenses of brown sandstone_________-_-_-_-- 15
Alternating white cross-bedded sandstones and pale shales__about 485
about 500
Hell : :
Gray Softer beds, pale sandstone and clay, with dinosaurs._. (Not measured)
Definition of the new name ‘‘Bear’’ is given on page 20.
All these beds are tilted here, but there is no evidence of angular
unconformity. The contact beneath the lowest hard sandstone of the
Bear is sharp but not more so than beneath other sandstones through-
out this series. Such a contact could, but does not necessarily,
represent a parallel or erosional disconformity. The change from
Hell Creek to Bear is, however, rather more abrupt than from Bear
to Fort Union No. 1, the latter being transitional through a thickness
of 15 to 20 feet, the boundary here taken by convention at a local shell
lens.
Dinosaurs are found in place, apparently as originally deposited, at
almost all levels in the Hell Creek, although no very good specimens
have been found in this field. JI have seen no dinosaurs in the Bear,
but Mr. Silberling informs me that he has found isolated, rare, and
very fragmentary specimens in the lower part of that formation, the
highest being 80 feet above the base in this section. It is entirely
possible that these few fragments were redeposited and derived from
the Hell Creek. No dinosaurs have been found in the upper 420 feet
of the Bear, but a few champsosaur and turtle bones and some in-
vertebrates occur.
Invertebrates from the lens here considered as marking the top of
the Bear have been identified by Dr. L. S. Russell as follows:
?Fusconaia danae (Meek and Hayden). | Viviparus formosus Meek.
?Nedionidus senectus (White). Campeloma nebrascense whitei Russell.
Elliptio priscus (Meek and Hayden). Campeloma limnaeiforme (Meek and
Viviparus trochiformis (Meek and Hay-| Hayden).
den). Physa cf. canadensis Whiteaves.
Dr. Russell remarks that the three pelecypods range widely in the
Northwest, Judith River to Fort Union, and that the species of Vivi-
parus characterize the Fort Union and equivalents (listing mainly
Upper Paleocene levels), the two Campelomas are likewise from the
Fort Union or equivalents, and the Physa is of little significance. He
concludes that the ‘fauna contains nothing characteristic of the Lance
and includes several species restricted to the Fort Union. It can be
regarded with some confidence as Paleocene in age.”’
18 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
As already noted, there are no exactly identifiable mammals from
Loc. 65, but the fragments found here are of Tertiary rather than
Cretaceous aspect, and the mammals from Loc. 78 are certainly
Paleocene and probably Middle Paleocene. It seems probable that
the whole Fort Union No. 1 here is of Middle Paleocene age and all but
certain that it does not include the earliest Paleocene.
There are two possible interpretations of this section. First, the
usual view, in analogous cases, that the Bear is Cretaceous, equivalent
to part of the Lance, with the necessary corollary here that part of
the Paleocene, a Puerco equivalent, is probably lacking. This in-
terpretation is possible, but it seems to me decidedly the less likely of
the two. The invertebrates indicate Paleocene and probably not
earliest Paleocene. Even if it be decided that they should be con-
sidered basal Fort Union rather than uppermost Bear, they are inti-
mately associated with the latter and in beds that grade into it in-
sensibly. This gradation itself opposes this interpretation, for it
makes the presence of an unconformity here, or a gap representing
Puerco time, seem unlikely. If a break exists it is more likely to be
within or below the Bear. The absence of dinosaurs, with the pres-
ence of such reptiles as did survive into the Tertiary, in most of the
considerable thickness of the Bear is also evidence against this view,
negative but of some weight.
The second possible interpretation is that most of or all the Bear
belongs in the Paleocene, probably representing the Lower Paleocene,
and that the Cretaceous—Tertiary boundary is in its basal part or below
it. All the items of evidence mentioned above favor this view. Op-
posing it are the possible presence of dinosaur bones in the basal Bear
and the absence of mammals. The dinosaur fragments are, however,
such as could very readily be redeposited from erosion of the Hell
Creek, and they are confined to the lower 80 feet of a series about 500
feet thick. It is entirely possible that there is a disconformity, or at
least a valid epoch boundary, in this series at the base of a sandstone
above the level of these bones, and still more likely that the dinosaur
bones are not really original fossils in these beds. The absence of
mammals has no weight. Mammals are rare throughout the field as
a whole, are generally excessively rare in the Lower Paleocene, in this
field almost never occur in sandstone, which is all that is well exposed
here, and even if present would be small forms easily overlooked.
The absence of dinosaurs, however, may well be significant, because
their bones are large, occur in most terrestrial Cretaceous formations,
and are very likely to occur where, as here, there are remains of other
types of reptiles.
Another summary section through the whole Hell Creek and Bear
was taken in sec. 15, T.6 N., R.15 E. This is continuous with the
lower Fort Union section of Stanton and Silberling given elsewhere.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 19
ae ees Baserorororbauniont Now) “alec wi aerrag 8 led vote
Clays with thin and inconstant sandstones, a more prominent
sandstone at the top not well exposed here_______________ 280
Bear {Gray to buff platy sandstones in beds usually one to three feet
thick, with thicker shale partings_____.........2_L_ 222 L- 330
610
Pale variegated shale with occasional soft blocky sandstones_ 765
Aer rane RATIOS CONC! atc) eee Re Eee ea 10
Mainly pale variegated sandstone___.___.......1._________- 270
Hell Heavy gray sandstone, with some shale________________.__- 145
Creek | Pale white to greenish clays with brown concretionary layers,
sandstones increasingly prominent toward the top________- 660
1, 850
fy oil a hie B* Sp Base oie Creek » f= oe ee ee
Yellow Sandstone and Somber Clay______________- (Not measured)
Dinosaurs are found in the Hell Creek in this region also, but no
animal fossils were found in the Bear.
The discrepancy in thickness of the Bear between this section and
that previously given, about 110 feet, seems too great to be due
entirely to difficulty of accurate measurement and is probably at
least in part a real difference. The localities are about 8 miles apart
in a straight line. It is also possible that the limits taken do not
exactly correspond in the two sections, as all the formations concerned
are highly variable.
Knowlton (in Stone and Calvert, 1910, p. 749) reports the following
leaves from “200 feet below the top of the Lance Formation”’, that is,
in the Bear at this locality: Sapindus affinis, Sapindus grandifoliolus,
Platanus aceroides, Platanus sp.?; and the following from a level still
lower by 200 feet, probably still in the Bear: Sapindus ?grandifoliolus,
Sapindus sp., Platanus raynoldsii. Knowlton unreservedly called
these Fort Union, but this has no bearing on the question here con-
sidered, since he also called true Hell Creek and Lance floras Fort
Union. All these species are reported from beds probably of Lance
age, but they are all equally characteristic, or considerably more
abundant, in the true Fort Union.
Throughout the northern part of the field at least, and generally
except where all the subdivisions of this part of the section tend to
merge indistinguishably into the Livingston, the beds between the
Hell Creek and the Fort Union No. 1, or basal Lebo, are a good
lithologic unit. The scanty data also suggest a distinctive paleon-
tological character. These facts and the possibility, or as I believe
probability, that the beds should be classified as Paleocene, or asso-
ciated with the Fort Union, rather than as Cretaceous and associated
with the Hell Creek or ‘‘Lance” make it highly advisable to distinguish
20 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
them by a separate name, and I have here called them ‘‘Bear’’,® from
Bear Butte around which they are typically developed. They may
perhaps be equivalent, approximately, to the Tullock, but this would
be an assumption that might result in serious misapprehension. They
are far removed from and discontinuous with the type Tullock, into
which it will never be possible to trace them, and their lithologic
character is not the same. It is improbable that they are exactly
equivalent to the Tullock, and even if this should prove to be the
case it would seem warranted and necessary to retain for them a
local name. At present correlation with the Tullock would be only
a guess, which might well prove to be incorrect.
Typical exposures of the Bear are shown in plate 2.
Fort UNION
The use of the name ‘‘Fort Union” has been so loose and ill-defined
that it has become necessary for every writer who uses it to propose
his own individual definition or to run the risk of being completely
misunderstood. In general it has been applied to beds in the Dakotas,
Montana, and Wyoming, in the northwestern high-plains region (and
in part intermontane areas) that are, or are supposed to be, later than
the Lance and earlier than the Wasatch. This apparently satisfac-
tory definition is in fact most indefinite. In the first place, there
has not always been general agreement even to this extent, Knowlton,
for instance, placing beds generally referred to or correlated with the
Lance in the ‘‘Lower Fort Union.” In the second place, the definition
is dependent on that of Lance and of Wasatch, which are themselves
very ill-defined. It is certain in some areas (notably Polecat Bench
in northern Wyoming, as shown by Jepsen) and probable in most or
all that strata generally referred to the Lance, often under the name
of Tullock but not necessarily equivalent to the type Tullock, are in
reality distinctly later than the typical Lance or the equivalent Hell
Creek and both faunally and stratigraphically are more nearly
related to the overlying beds, that is, to the Fort Union. Thus even
aside from the question of accurate recognition of the boundaries and
correlation of members of these formations and groups, there is often
doubt as to which group should include a given member. The time-
honored name ‘‘Wasatch”’ is still more ambiguous, to the point that
very few of the beds called ‘“‘Wasatch” are really equivalent to any
part of the type Wasatch. Granted that the use of the name is usually
intended to imply approximate correlation with the Gray Bull, there
still remain many doubts as to its proper contents, for there is generally
a thick series of beds, Tiffany, Clark Fork, and so on, that are some-
"Tan ndevied to Miss M. Grace Wilmarth, of the U. S. Geological Survey, for informing me that ‘‘Bear’’
and also “Melville’””. (defined on a Jater page) are not included in her records as ever having been used
previously as the names of stratigraphic units.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 21
times included in ‘‘Wasatch’’, sometimes in Fort Union, and sometimes
are separated from both as an intervening stage.
As a matter of personal opinion, I would prefer to use “Fort Union
group” for the whole Paleocene series of this northwestern plains.
area, to include all strata of age equivalent to or intermediate between
the Puerco and the Clark Fork. This usage is very broad, but the
designation ‘‘Fort Union” has already been so loosely applied that a
more restricted usage would be very difficult to frame or to maintain.
It at least has the virtue of being on the whole a natural subdivision
of the Tertiary and of including practically all the beds that have
ever been called Fort Union, except in out-and-out error or in such
wholly untenable classifications as that of Knowlton. For more
precise work it will in any case be necessary to define and use more
local names for particular formations and members included in the
Fort Union group.
In this field, the earliest workers recognized as Fort Union only
the beds from the basal No. 3 sandstone (as defined on a later page)
upward. Douglass, Stone and Calvert, Stanton, and all later workers,
however, have also included the underlying andesitic beds called Lebo
by Stone and Calvert. The name “Fort Union” is used throughout
the present study for the Lebo and all higher early Tertiary strata
in the area here considered. ‘The uppermost part of this series is of
unknown age and may possibly be as young as the Gray Bull, in which
case it should be removed from the Fort Union, but at present no
evidence warrants this step. In addition there is a series of strata,
the Bear, hitherto always considered as Cretaceous and referred to
the Lance, but in my opinion possibly Tertiary. If it should prove
to be Tertiary, I would place it in the Fort Union, but this is now
doubtful, and in this study the word ‘‘Fort Union” is not intended to
include the Bear.
The local Fort Union, thus defined, includes three mappable litho-
logic units of very unequal thickness. Mr. Silberling, who first recog-
nized these units, has applied numbers to them, with Fort Union
No. 1 at the base and No. 3 at the top, and his field designations have
been employed in publications by Stanton, Osborn, Gidley, and others.
In accordance with the general rules of stratigraphic nomenclature,
local geographic names are here applied, but throughout this discus-
sion I shall also employ Silberling’s numerical designations. The
correspondence is as follows:
No. 3 = Melville (new name).
Fort Union; No. 2 ap led
No. 1} _ 3
The No. 1 and No. 2 beds are generally similar, and both are
included in the Lebo of Stone and Calvert, but they are easily sepa-
22 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
rable throughout the field, and their distinction makes discussion
and records more exact. Both are said to be in large part andesitic,
and both are characterized by their somber color, the shales gen-
erally greenish and the sandstones dark brown, gray, or gray-green.
The No. 1 beds, or lower Lebo (shown in pl. 2), are characterized
by numerous lenses and beds of hard and resistant dark sandstone, so
that this unit is generally topographically positive and forms a ridge
or series of ridges. This characteristic is visible throughout the
field; for instance, typically in the gentle anticline in the northern
part of T. 5 N., Rs. 15-16 E., where the No. 1 forms an elevated hilly
area surrounded by a horseshoe valley developed on the No. 2 beds.
The upper limit of the No. 1 is taken at the top of the highest and
most persistent of its hard sandstones. The thickness, as measured
in secs. 15-22, T. 6 N., R. 15 E., is 496 feet (Stanton and Silberling).
It has not elsewhere been accurately measured. It may be somewhat
thicker in the western and thinner in the eastern parts of the field
but apparently does not vary greatly.
The No. 2 beds are topographically negative (see pl. 3). They
form valleys between the No. 1 and No. 8 sandstones, or slopes
beneath the latter. The characteristic material is greenish shale,
often rather coarse and sandy, with lenses and beds of gray sandstone.
When unweathered, these sandstones may be hard, for instance in
the overburden of the Gidley Quarry, but they weather rapidly and
are not resistant to erosion. It is this nonresistant nature of its
sandstones, and generally their somewhat lighter color, that dis-
tinguish this member most sharply from the No. 1. The thickness in
the measured section mentioned above is 840 feet and probably
averages 800 to 900 feet throughout the field. Stone and Calvert
(1910, p. 753) give a total thickness of 2,080 feet for the Lebo on Lebo
Creek. I did not measure the beds here (where they are not very
well exposed and have a variable and uncertain dip) but estimated
the thickness at not much over 1,500 feet, with about 600 feet in the
No. 1 and 900 in the No. 2. They give a total thickness of the Lebo
in T.6 N., R. 16 E. (that is, near the north end of Bear Butte) of
only 463 feet, which I think is surely much too small. It is highly
unlikely that this persistent formation thins out from 1,334 to 463
feet in less than 8 miles. The dip in this region changes rapidly, as
the beds are around the Bear Butte syncline, and exposures are not
continuous, so that exact measurement is not possible, but it is unlikely
that the thickness is much if any less than 1,200 feet here, with some
700 or 800 in the No. 2 and 500 or 400 in the No. 1.
The Lebo as a whole forms a narrow band along the northern edge
of the field, from the northeastern end of the Crazy Mountains almost
due east, but with some sinuosity, to sec. 23, T.6 N., R. 15 E. Here
they turn abruptly southward, and their exposure widens greatly
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 23
under the influence of the Widdecombe Creek anticline, the axis of
which is mostly on the lower Lebo, with the upper Lebo forming a
horseshoe valley around it, the eastern limb being occupied by Widde-
combe Creek. The exposures then swing around the northern end of
Bear Butte (with the No. 2 also continuous through the gaps across
the axis of the Bear Butte syncline) and then swing southward and
widen until they form a very wide area of low relief in the vicinity of
the Glass Lindsay lakes (Lake Adam and Lake Walvoord). The upper
limit against the No. 3 swings abruptly westward in sec. 34, T. 4 N.,
R. 15 E., and runs over to the Crazy Mountains, which it reaches
some 17 or 18 miles south of its northern departure from those moun-
tains. The exposure as a whole thus forms a great loop closed on the
west by the mountains, as shown in plate 1.
The No. 1 and No. 2 beds seem to be perfectly conformable and to
intergrade, forming a natural unit, sandier in its lower part, so that
the single name Lebo for both is acceptable. In the northern part of
the field they are generally sharply separable, but in the south it is
often difficult to distinguish them. It is to be noted, however, that in
this southern area they are nearly horizontal and are very poorly
exposed and that in this direction all subdivisions, even between
undoubted Cretaceous and Tertiary, tend to break down or to be
very difficult to distinguish.
The best exposed section showing the whole thickness of the Lebo
is In secs. 15—-22,° R. 6 N., T. 15 E., where it has been measured by
Stanton and Silberling who give the following section (Stanton, 1909,
p. 263, here slightly modified):
No. 3{ MASSIVE SATUSLOM Cae cetera cece eerie arn earn eae re aes See (Not measured)
Feet
Shale with a few thin bands of sandstone____________-_----_- 112
RGAE BAO SL OTIC B.S ee me Bey che a Coa ST al ly Ge ed 5
BSI URS San SF =, oe oa rs EE ter a pnp 18
Gray limestone, weathering brown [a concretionary layer, not a
Norte) “continuous stratum] 2209? eeGeen ) of tie eek Ae ee 3
Greenish-gray somber shale with much soft sandstone of same
color and brown .... concretions in lower third, a few thin
bands of sandstone in upper part and several concretionary
ZOWMEB TRC ATA UO [0 eye ee a ye a ee an 700
838
Brown, thinly cross-bedded sandstone forming... . ridge____- 32
Newd [Somibermereenisil Rs hyall ewer eeses ree em cee re mere 200
‘er "Greenish-eray sandstanes 2) a4 ee EY tee a 15
Gréchish=pray elialess). 2252 eee _ Gers yt eee 249
496
A section of the underlying beds at this same locality is given on a
previous page.
9 Stanton says sec. 15, but the greater part of the beds are here in the adjacent sec. 22.
119212—37 3
24 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Stone and Calvert and others have given other sections, but they
are too generalized or include too many unexposed parts to be very
helpful.
The Fort Union No. 3 beds (see pl. 6) are a great mass at least 4,000
feet thick, and possibly as much as 6,000 if the highest strata of this
series in the Crazy Mountains be included. Determinable fossils are
known only from the lower 3,000 feet, and this is the part to which
attention has been particularly directed. In spite of the great thick-
ness and heterogeneity, there is no convenient lithologic or paleonto-
logical basis for subdividing the beds. They consist of shales and sand-
stones, most of them lenticular and highly variable. The usual topo-
graphic expression is a series of ridges on the sandstones and valleys
on the shales. The shales, particularly at the mammal localities, do
not differ greatly from those of the No. 1 and No. 2 in appearance, but
the sandstones are lighter in color and are generally more resistant than
those of the No. 2. Since the shales are poorly exposed, the general
impression is of a much paler formation than the underlying Lebo.
The massive basal No. 3 sandstone is the most continuous and proms
inent horizon marker in the Fort Union of this field and has been
remarked by everyone who has worked here. It almost everywhere
forms a prominent scarp, and its resistance to erosion is the cause of
the elevation of Bear Butte, Lion Butte, and numerous less notable
hills and escarpments.
The base of this sandstone forms a natural division plane throughout
the field and is evidently an erosional disconformity, although it is
unlikely that it marks any considerable time gap. The sandstone
tends to become less massive in the southern part of the field toward
the south end of Lion Butte and where it swings westward to the
mountains, and it is here generally more platy and formed by numerous
thin beds with shale partings but can be traced continuously almost to
the mountains.
The fluviatile nature of these beds and the presence of numerous
channel and flood sandstones make it possible that there are discon-
formities at almost any level, but none can be detected as of any regional
significance, and the whole series seems to be essentially continuous
and without any noteworthy or sudden change in general type of
sedimentation.
The base of the No. 3 is further made noticeable, especially from
the air, by almost everywhere supporting a growth of evergreens
(pls. 3, 5). This is the more noteworthy because the sandstones of
the No. 1 beds, even where almost identical with those of the No. 3
in topography and elevation, do not support any trees, and the Lebo
in general is almost devoid of large vegetation except for cottonwoods
along the stream courses.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 25
The No. 3 beds occupy an irregular area, somewhat more elongate
east and west than north and south, bounded by the Crazy Mountains
on the west and by the loop of Lebo exposures on north, east, and
south (pl. 1).
From their position over the Lebo, it may be supposed that the
No. 3 beds correspond in their lower part to the Tongue River and
perhaps in their upper part to the Sentinel Butte, but such a correla-
tion is at present totally unwarranted. They are very distant from
the typical or from any unquestionable exposures of the Tongue River
or Sentinel Butte, their lithology is no more like either Tongue River
or Sentinel Butte than like many other formations and certainly is not
close enough, in itself, to warrant correlation without tracing them
laterally continuously or nearly so into true Tongue River and Sentinel
Butte, which is impossible. Their age is well established, in part, as
brought out below under ‘‘Correlation’’, but that of typical Tongue
River and Sentinel Butte is not, and paleontological correlation with
those members is not now possible.
Under these conditions it is certainly less helpful than conducive to
serious error to adopt the frequent practice of assuming that a corre-
lation exists. Still worse is the practice, also exemplified by some
work on the Fort Union, of assuming that both Tongue River and
Sentinel Butte must occur here and dividing the beds, in which no
natural division has been established in the field, according to the
proportionate thickness of these members in a widely different area.
I therefore propose the local name Melville for the lithologic unit,
from the town of Melville, which is situated on these beds and is
surrounded, within a few miles, by excellent and typical exposures of
them. The lower boundary of the formation is well established, as
shown on the accompanying map. The upper boundary is still
uncertain. The name is proposed to include at least the lower 3,000
feet of the No. 3 beds, to about the top of Cayuse Butte, and tenta-
tively for the whole No. 3 of this field, to the highest sediments on
Porcupine Butte. Later discoveries might make it advisable to
remove some of these uppermost strata from the formation, and the
pertinence of still higher beds around the mountain flanks is wholly
dubious.
Concretions are common throughout the Fort Union here. Limy
concretions, weathering rusty yellow, may be of great size, up to 10
feet or more in greatest diameter, and locally characterize a definite
stratum, but these appear to be truly concretionary and not a true
sediment or limestone. Shell limestones do occur locally in the No. 3
beds, but in the No. 1 and No. 2, while shells may be fairly abundant
in relatively small lenses, they are generally in a shale matrix and do
not form a true limestone. In the No. 3 beds there are a few thin
bands of comminuted shells, or shell breccia (notably at the Scarritt
Quarry), generally mixed with clay.
26 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
The relatively small quantity of carbonaceous material is note-
worthy in ail three subdivisions. There are a few thin impure and
local lenses of coal in the No. 3, and a little prospecting has been done
on these, but none are of any commercial value. Aside from these
thin seams, generally only an inch or two thick, there are a few car-
bonized tree trunks, occasional very local lenses of coal a few feet in
diameter and less than an inch in thickness, and locally many minute
carbon fragments and filaments. In marked contrast with the Fort
Union of most other areas, these rocks can be classed as not coal-
bearing.
Several workers, especially Stone and Calvert and Silberling and
I, have attempted to follow out the development of this Fort Union
series into regions beyond the local field, but with indifferent success.
To the eastward it ends against the Cretaceous, and the Fort Union
reappears, considerably modified in thickness and character, after a
long gap, in the Bull Mountain Field (see Woolsey, Richards, and
Lupton, 1917; also Ellis and Meinzer, 1924). The lower part of the
Fort Union is there predominantly a shale member, dark and greenish
in color, with some sandstone (not closely similar to that of the No. 1
in the Crazy Mountain Field) and coal, about 200 to 300 feet in
thickness. This is commonly correlated with the Lebo, which is
probable on lithologic grounds, but there is no evidence that it repre-
sents the whole Lebo or that it is not a lithologic facies of somewhat
different span in time. The correlation is here more probable than
in any other area where the Lebo is supposed to occur, but it cannot
be considered as established beyond doubt. The upper part of the
Fort Union is here only 1,650 feet thick and contains more pale shale,
more and different limestone, more numerous and persistent hard
sandstones above the base, and much more coal than does the No. 3
of the Crazy Mountain Field. The Bull Mountain Fort Union is an
isolated mass, completely surrounded by Cretaceous outcrops.
The Fort Union encircles the Crazy Mountains, which are formed
principally by intrusive masses thrust into it, and has been followed
in some detail by Stone and Calvert (1910). (Silberling and I have
also made a reconnaissance around the mountains on which, as well
as on Stone and Calvert, my remarks are based.) The Upper Creta-
ceous formations and the Lebo, steeply folded and much disturbed
and altered by later igneous activity, swing around and into the
northeastern end of the mountains. The Hell Creek here appears to
contain more andesitic debris and comes to resemble more closely the
Lennep and the Lebo. Toward the southwest, and southward on the
western flank of the Crazies, the Hell Creek, Bear, and Lebo have not
been distinguished. It seems probable that they here merge litho-
logically with the Livingston, as Stone and Calvert believe, or they
may possibly be absent. There remains, however, the possibility
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 24
that more detailed study and discovery of fossils, especially verte-
brates, would permit their differentiation here. West of the moun-
tains the late Cretaceous and early Tertiary strata are thrown into a
series of folds, roughly parallel to the mountain flank and with north-
south trend. There is no wide zone of Fort Union, as east of the
mountains, but strata lithologically similar to the Fort Union do occur
in narrow zones, as folded. Some of them are almost identical in
character with the Melville beds of the eastern flank and include
abundant leaves. This Fort Union facies, overlying the Livingston,
also occurs in the southern part of the mountain area, but it is much
disturbed and poorly exposed and not enough work has been done to
trace its continuity with the well-differentiated series in the north-
eastern area. It is probable, as Stone and Calvert suppose, that it
includes only the upper part of the Fort Union of the latter region.
No mammals have been found in it.!° There is a large area litho-
logically like the Melville around the southeastern flank of the
mountains also, but here again exact correlation is impossible at
present, and considerable search has not yet revealed any mammals
or other fossils indicative of exact age.
The Fort Union exposures are surrounded by older rocks throughout
the northern and western areas, and no extension or correlation of
the beds in these directions is possible.
Following the beds southward, the division between the No. 1 and
No. 2 tends to break down, and this is probably true also of that
between the Hell Creek, Bear, and No. 1 Fort Union near the Yellow-
stone River. The beds here take on a violet hue, especially the
shales, a color also seen in the northern area but there rare and here
predominant. The indivisible beds so colored apparently include the
Lebo, probably the lower part of the Melville, and also extend down
into the Cretaceous—that is, this part of the series is blending into
the undivided Livingston, as reported by Stone and Calvert.
There is a dark sandstone that may represent part of the No. 1
Fort Union skirting this area and visible near the 4,700-foot contour
on the south of the divide between the Yellowstone and Stillwater
Rivers, south of Reed Point, and also apparently at Absarokee, but
the identification is uncertain. If this is the No. 1, it represents the
farthest point to which a definite subdivision of the Crazy Mountain
Fort Union can really be traced, even in this highly dubious fashion,
as far as I have been able to ascertain. We were unable to establish
any continuity with the Red Lodge or Polecat Bench areas, and
lithologically the beds in those areas are not comparable to those of
the Crazy Mountain Field, nor are similar subdivisions recognizable.
10 A bout 1910 a sheep herder showed Mr. Silberling a jaw of an animal similar to Pantolambda that he said
was found near the head of Shields River, or between it and Potter Creek. It was impossible to obtain the
specimen for exact identification or to verify its reported origin.
28 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
They include nothing really comparable with the Lebo, and the re-
semblance to the Melville is too vague to have any real correlative
value. Paleontological correlation alone seems to have any sig-
nificance between this region and that near the Crazy Mountains.
STRUCTURE
The beds of this field are almost nowhere exactly horizontal and in
places are steeply tilted. Even in the course of purely paleontological
work it is necessary to take strict account of the structure, since
relative levels between the numerous isolated exposures can seldom
be measured directly but have to be calculated from the structural
data.
Along the north side of Fish Creek, from the mountains eastward
to sec. 23, T. 6 N., R. 15 E., there is a strong monoclinal flexure dip-
ping south at angles of about 40° to 75°. North of this fold only
Cretaceous beds are exposed. The flexure itself involves the upper-
most Cretaceous, Bear, Lebo, and basal Melville. The strike is
sinuous but is mainly east and west to the end of the Crazy Mountains,
where the Melville beds mostly run into that range, while the lower
beds swing around its northern end. In the section noted, this fold
ceases to affect the Fort Union beds, which are affected south and
southeast of here by a broad anticline with northeast-southwest trend
and low dips up to about 12°. Erosion along the axis of this anticline
has formed a great embayment, about 6 miles wide at its mouth and
of about the same depth, north and south, surrounded by a high rim
on the basal Melville. Widdecombe Creek flows along the soft No. 2
zone on the eastern limb of the anticline. Directly east or southeast
of this anticline is a parallel syncline the axis of which is occupied by
remnants of the basal Melville sandstone rising abruptly above the
No. 2 slopes and valleys. Puet Creek cuts deeply into this, separating
the axial elevation into the long isolated Bear Butte to the northeast
and Lion Butte, to the south and connected with the great mass of
No. 3 beds extending westward to the mountains.
The Hell Creek, Bear, and Lebo swing around the north end of
Bear Butte, dipping toward it. The dip increases in intensity here
away from the actual Butte, until in the upper Hell Creek northeast
of the Butte it reaches about 30°. The Lebo flanks the long east scarp
of Lion Butte with low dips, usually 4° or 5°, toward the latter, vari-
able and affected by slight local disturbances. South of here, toward
the Glass Lindsay Lakes, the Lebo is nearly horizontal, with dips up
to 1° or 2°, erratic in direction but oftener to the west.
Over the greater part of the Melville beds area, south of the strong
monocline and west of the Widdecombe Creek anticline, the dips are
prevailingly westward and fairly consistent at 4° or 5° over a large
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 29
area, to the western part of T. 5 N., R. 14 E. Here the wide pass
between Porcupine Butte and Cayuse Butte is in the very broad,
poorly marked syncline or basin. The beds around Porcupine Butte
dip northeasterly into this area, although in the Butte itself the dip
(about 5°) is nearly north.
There are a few visible small faults with a throw of a few feet, such
as one at the Silberling Quarry, but these are negligible in beds of
such great thickness. No faults of sufficient importance to show on
the map or to affect stratigraphic leveling significantly were detected.
The deformation appears to have been entirely post-Fort Union,
and nowhere in this region was any angular discordance detected
between the various Cretaceous and Tertiary formations, even down
into the Lower Cretaceous (Kootenai) in the domes north of this
area. Itis areasonable assumption that the deformation was approx-
imately contemporaneous with the post-Paleocene igneous intrusions.
FOSSIL LOCALITIES AND FAUNAL LISTS
GENERAL OCCURRENCE OF FOSSIL MAMMALS
Fossil mammals, represented at least by material adequate to show
its mammalian nature, have so far been found at 57 localities in this
field, of which about 35 have yielded material sufficiently well pre-
served for generic identification, and about 25 material specifically
identifiable and of some real value in correlation and faunal studies.
The great bulk of the collections comes, however, from the three locali-
ties where quarries have been developed.
Although some of the more resistant sandstones, such as those in
the No. 1 beds or the basal sandstone of the No. 3 beds, are well ex-
posed and form more or less continuous outcrops wherever they occur
in the field, the finer and less resistant sandstones and the shales and
clays are on the whole very poorly exposed. Bones are occasionally
found in the sandstones, but they are there very rare and are generally
of no value. Only one identifiable mammal has ever been found in a
true sandstone in this field. The mammal localities are therefore
almost entirely on the rarer shale exposures, which occur where coulees
have cut the shale slopes or where the wind has developed blow-outs.
Such exposures, seldom as much as a hundred yards in diameter and
generally much less, are limited in number. In the productive area in
this field there are probably not over 400 of them, and all of these have
been prospected by Mr. Silberling, many of them also by me or others.
The mammal occurrences may be grouped under two categories, as
surface localities or as (actual or potential) quarries. At the surface
localities, much the more numerous of the two, the mammal remains
are rare, as far as known, and are so sparsely scattered through the
matrix that only accidental finds or concentration from long weather-
ing and wind erosion leads to any production. The ideal conditions
30 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
at such localities are deep weathering in situ without erosion or surface
drift or wash, combined with gentle deflation, which removes the
small weathered shale particles but leaves the larger or heavier fossils.
Such conditions are relatively rare, and it is also noteworthy that
numerous localities that were in good collecting condition when first
found 30 years or so ago have now lost much of their value or promise
by drifting over of windblown material or surface wash, by the spread
of vegetation onto their weathered surfaces, or by active erosion,
which removes the surface concentrates and leaves only a clean, hard
shale exposure in which there is little chance of finding a fossil in situ.
The quarry localities are those where fossils are so concentrated in a
local pocket that it is profitable to work the bed as a whole and recover
fossils in place. The difference is, of course, of degree and not of
kind but is one of great practical importance. Were it not for its
three principal quarries, which have been called the Gidley, Silberling,
and Scarritt Quarries, this field would be of relatively little importance.
There are marginal localities also of some importance, intermediate
between quarries and straight surface localities. Thus Loc. 81 (as
listed below) was literally a quarry, but the whole bone pocket and
therefore quarry was only about a yard in diameter. Loc. 25 has
yielded so much surface material that a concentration of probable
quarry calibre is indicated, but the rather limited attempts made
to quarry at that locality have not in fact developed a profitable
bone layer.
An outstanding characteristic of the field, regardless of level or
geographic position, is the fragmentary nature of the material. In
the hundreds of specimens collected, there are so far known only four
or five mammal specimens complete enough to be called skulls, and
only two of these really adequately reveal most of the skull structure.
Only about 10 specimens include associated upper and lower teeth,
and only three any surely associated limb bones. Nothing approach-
ing a complete skeleton has ever been found. This fragmentary con-
dition is seen not only in the surface specimens but equally in those
found in situ deep in the quarries. The quarry specimens commonly
show fresh breaks that look recent and yet abut against undisturbed
matrix. It is also peculiar that most of the quarry specimens had
lost some of their teeth before burial and that jaws quite devoid of
teeth are relatively abundant.
For his own records and in connection with the National Museum
collecting, Mr. Silberling has numbered every locality where any fossils
were found. These serial numbers are here adopted and are those used
throughout the present work. There are now 82 numbered localities;
25 of these are not mammal localities, but for completeness and the
convenience of later workers they are all given in the serial list on a
later page. The map (pl. 1), however, shows only mammal localities.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 31
THE GIDLEY AND SILBERLING QUARRIES
The greater part of the National Museum collection, about four-
fifths of the identifiable specimens, is from the Gidley and Silberling
Quarries, of which the Gidley Quarry is far the more important, with
nearly seven times as many specimens as the Silberling Quarry.
The Silberling Quarry, Loc. 1, was located, as a surface prospect,
by Mr. Silberling in 1902, and he subsequently made a small collection
here that formed the basis of Douglass’ publication in 1908. In 1908
Silberling opened the quarry for the National Museum and then
collected most of the specimens known from this locality. In 1909
the much richer and more easily worked Gidley Quarry drew his
attention away from the Silberling Quarry, and little work has since
been done there. Silberling has done some further prospecting,
however, and in 1935 the Third Scarritt Expedition reopened the
quarry and worked it for a few days, but abandoned it on finding the
bed bone poor, the stripping very difficult, the fauna essentially
duplicating that of the Gidley Quarry, and the matrix unsatisfactory
from the point of view of preparation. This quarry did, however,
produce the splendid Ptilodus skull and partial skeleton described
by Gidley, and it is the only locality in this field where Psittacothervum
or Elpidophorus minor have been found. All its other genera and
species are represented by about equally good or better material
from other localities.
The Silberling Quarry is in NESW sec. 4, T.5 N., R. 16 E.,
in an embayment near the middle of the east side of Bear Butte
(see pl. 5). The fossil horizon is about 75 feet below the base of the
No. 3 sandstone and is the highest level in the No. 2 that has yielded
identifiable mammals. The bone layer is not well defined by any
visible criteria but is limited to a zone 1 or 1% feet in thickness.
The matrix is a fine greenish tuff or shale, very tough and harsh,
extremely abrasive to handle, and difficult to work in preparation.
It grades laterally into a bed with numerous fresh-water bivalves,
among which mammals also occur, but this matrix is so hard that
preparation of fragile specimens would be almost impossible.
The Gidley Quarry, Loc. 4, is in NWNEY sec. 25, T. 5 N.,
R. 15 E. (see pl. 4). It is immediately adjacent to the county road,
on its east side, where it descends the steep hill from the basal No. 3
rimrock to the valley of the upper part of Widdecombe Creek, on
the relatively unresistant and topographically negative No. 2 beds.
A small coulee here descends the slope, in a westerly direction, and
cuts the bone bed apparently near the middle of the rich pocket in
which the Gidley Quarry is developed. The locality was discovered
by Mr. Silberling as a surface prospect in this coulee in 1905. When
Dr. Gidley visited the field in 1909, Mr. Silberling showed him this
locality as the most promising of any in the field. The surface
32 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
material was unusually abundant but so disintegrated as to have
little value. Dr. Gidley dug in along the bone stratum until firmer
material was found in place, made a good collection from this bed,
and thus started the quarrying operations that Silberling and others
have continued intermittently ever since. Mr. Silberling’s opera-
tions for the National Museum, resulting in the bulk of the collection
here described, consisted in stripping and working out an area of
about 1,400 square feet (a very rough estimate). The other important
operation, that of the Third Scarritt Expedition in 1935, extended
over an area of about 1,750 square feet (also a rough approximation,
as the area was irregular and not all uncovered at once).
The quarry consists of two cuts, one north and one, of smaller size,
south of the coulee and original surface exposure. The material
collected by Silberling was carefully labeled as to the cut from which
it came, but in this study there was found to be no significant differ-
ence between the two parts of the collection, and it is all treated as
a unit. The greater part of the worked-out area has been filled in
again in later stripping, and the cuts left open weather and fill rapidly,
so that the form of the quarry is not apparent in the field. The north
section has probably been about worked out, except for a probably
very rich corner left under heavy overburden. The south section
was still rich along the margin as left in 1935 and probably would
produce over an area of at least 1,000 square feet, and possibly 1,500,
before the bone layer ran out into the hillside, so that the locality
as left in 1935 is, as far as such things are predictable, still capable of
producing another collection about as large as either of the two se
far made there. The quarry has so far produced about 800 good
identifiable mammal specimens and perhaps 1,500 single teeth and
other unimportant fragments.
The areal distribution of the fossils is very erratic and patchy.
In places it is possible to work for 1 or 2 days without finding any
jaws, and in others one man can collect ten or more jaws in a day.
In general, however, the fossils seem to be distributed in an elongated
area, about 5 to 20 feet in width, usually nearer the smaller figure,
and with a tested length of at least 150 feet, which probably will
continue to a much greater distance. The general trend is north-
northeast to south-southwest.
In many places the fossils are concentrated in a single and fairly
well defined layer an inch thick or even less in which fragments of
bone may be so numerous as nearly to make a bone-bed. ‘This
material is, however, very fragmentary, and good jaws are exceptional
in it. In other places the bone layer is less definite, and the fossils
are scattered more sparsely but generally in better preservation through
a thickness of about a foot, or up to about 18 inches at most. Oc-
casional fragments are found in the nearly barren material above and
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 33
below this more definite fossil horizon but (as far as observed) only
within a few inches of it. The level is about 125 or 150 feet below
the base of the No. 3 sandstone. Some additional remarks on the
occurrence of fossils here are made in discussing the facies and ecology
of the quarry fauna.
Table 1 gives a complete list of the fossils so far identified from the
Gidley and Silberling Quarries, with the number of upper and of
lower jaws of each species, based on the National Museum collection
only except Elpidophorus minor, the one specimen of which is in the
Princeton Collection. It is probably, but not quite surely, from the
Silberling Quarry.
TaBLe 1.—Fossil mammals so far identified from the Gidley and Silberling Quarries,
Crazy Mountain Field, Mont.
|
Gidley Quarry Silberling Quarry
Species
Upper Lower Upper Lower
jaws jaws jaws jaws
MULTITUBERCULATA:
Ptilodontidae:
PATEL OGIESH IL OTILON) 1G tees en a en ee a ee 39 25 6 ll
Pe tOUUSIQOUGUISS awa o ee a ae Re ee ne = | a eae See g LA ates ae eae 1
CETOMUSIGIIEYT== ae oon a he Need Eeael eee ees O92 nen eee 3
CAPE ENTITES Oe Hy a a LE ee eee ae oe eee neeee 143) 2 eee 3 4
JEST TONG] ays oe fel ses Be ae RSs A Ne be ela nap ee OA Ps Se ee (ea 1
PEREUDOUUISIOTON TCT see ke eee ees ese em. Pk eer! Ls 5
PEUCLYU DOGUSMUSSEL te nee 2 See eee ee aes | eee Pj Wns See ee 1
PEE DOUUS CILOCTUNG aoe eee ee a en ee ee | 1
PIOTECY DOLUS I ODSCN tease a PR nen eee eS eo
FEUCOSTLORON ES DOAT SIS ha ae ete ee ee ee ee od ei ee eee 1
INSECTIVORA:
? Deltatheridiidae:
Gelastops Pancuess= tJ Sk eles see ie oh ie 28 1 Rs eee 1
Leptictidae:
PF OdICOMOTE CONCONULAT CEN StS see eae ea en nae eae eeee |e ee eee | 1
SRE DUILCOCOTINLG UM Canam ane e mee e eaa oa aee e as SE de 13
EDLACONOTUINAUTLSCULU Maan Oe oe eae a a seo no aoe sae ceo 1
Myrmecoboides, montanensis............-.--.------------ 1 2
Nyctitheriidae:
ISHLDNOGON: SUNUDLICILENS -- aan aco oe ee teen oe eee cea asa ceee 1
Pantolestidae:
PBESSOLCELOTECIUUCILL =e mee ee ree eee ee eee 2 sl 1
ZAM NTON OT1L8 fF OLA LON ae ee ee 8 1 | aes ee ee 3
Mixodectidae:
HALA EMONEMA CUSPIAN OG sas eee een eae ene ceases 1 TlLgos. ee 1
PE DIAC DROTUS NINO 22 2oe = a= ee ee es See Ae ae oe |S oa oe selon eee eae 1
Picrodontidae:
Picrodirs-sil benlingyt se ae es ee tes ss) d/o eee ee ty) cee es 1
PRIMATES:
Plesiadapidae:
iPronothodectesimattheiwt. 22 = tees as eae 3 eee 1 8
Carpolestidae:
EAC OLUT SUIS LOT ENC On a= aoe ee ee ae ee ee 1
? Anaptomorphidae:
IPATOMOMYS MAUL US xa cee oa ae = ee ee 6 32 1
PUTONLONIGS CE DT CSSILEN Se a eee ee ee 3 4
‘Palaechthomalticicepige: se) ieee Bie be rae ee 2 ee ee 1
PROLENOCHUR AWOL aoe oe aoe = 2 ee a ee 2 6
34 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
TABLE 1.—Fossil mammals so far identified from the Gidley and Silberling Quarries,
Crazy Mountain Field, Mont.—Continued
Gidley Quarry Silberling Quarry
Species
Upper Lower Upper Lower
jaws jaws jaws jaws
TAENIODONTA:
Stylinodontidae:
(COMONUCLESICOIM Nid eon ae 9 eee et eee 18 Pes eee 1
POStULOCOLRETIRLTI TIL LILI UTI ee as ee ee eee 1
CARNIVORA:
Arctocyonidae:
Clacnodonumontanensis 2212 2 sae ee 1 2
Claenodonisilberlingi=se es ee ee ee ee | 1
Claenodon:latidens24o% <a SNES eae [oes ooes 1
Clacnodon'sp =o 56 eS Or AE ee th eee | Wee ee, Sod
PROUT Y DLA COMON JUnENS teem ae ee ee ese eee Z| oes 1
MCLACHTIACIS3D ULNiLOT ates ee eet te eel 3 TIM os 3
ISPOUNOTYOCONOLTUNCULUS = ee tek ee a Se ll ee 1
MUTOLTICENLES LALidenNs eee ten ies aoa Sk ee | eee ete A eee eee 2
Mimotricentesiangushidensseres. A se oe SP | ee 1
Miacidae:
Didymictisimicrolestesss2—. sso l2e- eo Se 4 13 1 1
DiGUINICLISILCNULS pane Ale ee ee LO Serie Pee | Oe ee ee 1
Didymictisi@Rayaenia nies .a- ae eee ee eee tee || es BP eee 1
Tehidopappusimustelinius_- 2222 -22sseen sees ee 1 1
Mesonychidae:
DiSSacu sis porn 2 tee See ene ae Fe roe int Oe ee El See PEE i Us ieee eR 1
CONDYLARTHRA:
Hyopsodontidae:
STI LADSONOMIAQIILONIUS seen ee ee ee eer | 17 34 1 7
IG OLELES AIST CLUS eens Sa eee ee ee 2 9
THALOMY US CiSSCnlaneusas = ose ee a ee en 2 3
Lo plaletesidiscepiatnitiane seen sa ane ee 2 th
Phenacodontidae:
Petraclaenodon sy MUCUS ease no n= ne eee ee eo ee eh meee |e ee ee eee 1
Metnackaenodon cla MuerCensis- saa as eee 2
Periptychidae:
ConiphagusvmOntanUssacae aaa aes ee eee 1 (ial pee ie a 1
FANIBONCHUSISECLONI USS nee oa eee eee enna! ee eee es 4 3
PANTODONTA:
Pantolambdidae:
(PantolambdarinienmMediusseee ce ae ae eee ee ee | SR
EPantola mOdaiSP sea-s eee he eee ee ee en een | Re See. 1
107 275 13 45
ABOU WO KD Sees Ne Op ee oe eee 382 58
440
THE SCARRITT QUARRY
The fauna of the Scarritt Quarry is not described in this memoir,
being known only from material in the American Museum that has
been published separately, but it is included in the faunal lists here
given, and a general discussion is essential in the present consideration
of the field as a whole. This locality, Loc. 56, was found by Mr.
Silberling years ago and a few surface fragments collected. He located
the bone layer and planned to attempt quarrying, but this plan was
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 35
not carried out until 1935, when the Third Scarritt Expedition opened
a quarry here and made a collection of about 50 jaws and numerous
teeth and odd fragments. The locality isin SEMNW* sec. 13, T.5N.,
R. 14 E., on the eastern slope of the low divide or spur that extends
northward from Cayuse Butte. The horizon is estimated to be about
2,000 feet above the base of the No. 3 beds, hence about 2,150 feet
above the Gidley Quarry and about 3,350 feet above the base of the
recognized Fort Union of this area. As it is quite impossible to
measure a continuous section between any of these datum planes, the
horizon is approximate only but is probably of the right order, and
the quarry is unquestionably much higher stratigraphically than the
other quarries, and the highest in the field from which much identi-
fiable material has been found except for Locs. 11 and 13, which are
clearly higher, probably by about 1,000 feet.
The fossil level is marked by a bed, varying from a mere film up to
about 4 inches in thickness, almost entirely composed of shell frag-
ments. Mammals occur in this shell bed, and also in the clay (with
more scattered and more complete shells) within 2 or 3 inches of it,
both above and below. As far as the bone pocket has been followed,
it is much less rich than the Gidley Quarry, but the material is good
in average preservation and association of upper and lower jaws is
relatively much more frequent than in the other quarries. (Four
instances of association occur among the 50 jaws collected here, while
such association has so far been found only once in the Silberling
Quarry and once in the Gidley Quarry.) The fauna so far collected
is as follows:
Ectypodus hunteri: 2 upper and 4 lower jaws and 27 isolated teeth.
Ptilodontid undetermined: 1 tooth.
Leptacodon cf. tener: 1 lower jaw.
Bessoecetor thomsont: 3 upper jaws, 9 lower jaws, and 1 specimen with associated
upper and lower jaws.
Cf. Palaeosinopa sp.: 1 tooth.
Elpidophorus patraius: Associated upper and lower jaws, 1 upper jaw, 1 lower
jaw, and 5 isolated teeth.
Unuchinia asaphes: 1 lower jaw.
Plesiadapis anceps: Associated upper and lower jaws and 6 isolated teeth.
Carpodaptes hazelae: 1 upper and 3 lower jaws.
Phenacolemur frugivorus: 1 lower jaw.
Cf. Chriacus sp.: 1 tooth.
Litolestes notissimus: Associated upper and lower jaws and 19 isolated lower jaws.
Tetraclaenodon sp.: 1 upper molar.
Pantolambdid undetermined: 2 broken teeth and parts of limb bones.
OTHER IMPORTANT LOCALITIES
The following are faunal lists for and some notes on localities other
than the three quarries that are of some importance. They include
36 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
all the localities for which mammalian material that can be identified
is available, and also one locality of which this is not true but which
is important as being the highest stratigraphically where mammal
fragments have been found. All these localities merit repeated pros-
pecting in the future, and any of them may turn up material of out-
standing importance. The same is also true, but with less probability,
of mammal localities, not especially discussed here but all given in the
serial locality list, from which no identifiable specimens are now at
hand.
Fort UNION No. 1, oR LOWER LEBO
Loc. 65.—Sec. 26, T.6 N., R. 16 E. This is the lowest horizon at
which mammals have been found in this field, being only about 35
feet above the base of the Fort Union No. 1, or of the Lebo. Itisa
small shale slope immediately north of the south line of the section
and on the west side of a wagon trail that follows the base of the Fort
Union No. 1, on the underlying sandstone ledge. The only identi-
fiable mammal yet found here is a Py, inseparable from Ptilodus
sinclairi, mentioned in connection with the systematic description of
that species. We have recently found here a few scraps of mammal
bones, also crocodile or champsosaur teeth and ganoid scales, but the
material is very scanty and poor. This is, nevertheless, the most
promising prospect for obtaining material near the basal contact of
the recognized Fort Union in this field.
Loc. 78.—Sec. 26, T. 6 N., R. 16 E. This locality is in the same
section as Loc. 65 but farther west, on the other side of a sandstone-
capped hill and at a higher level, about 200 feet above the base of the
Fort Union No. 1. The only identifiable specimen yet found at it
is the lower jaw made type of Chriacus pugnac.
Loc. 9.—Sec. 35, T. 6 N., R. 15 E. This is the most promising
locality for mammals in the No. 1 beds. It is a good shale exposure on
the west flank of the Widdecombe Creek anticline, about 200 feet below
the base of the No. 2 and hence probably about 300 feet above the base
of the No. 1, although this cannot be measured accurately. Search in
1935 revealed no new material. Previously the following had been
collected: Lower jaw fragment of ?Mimotricentes sp., type upper jaw
of Claenodon vecordensis, and two upper molars (Princeton no. 13757)
of Tetraclaenodon ?symbolicus.
Loc. 78.—Sec. 34, T.6 N., R. 16 E. This locality is m the somber
capping sandstone of the No. 1 beds, nearly 500 feet above their base.
It has yielded only one mammal, a lower jaw of Mimotricentes angusti-
dens in the Princeton collection. This is the only identifiable mammal
to be found in a sandstone in this field. Subsequent search has not
brought to light any other fragments at this locality.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 37
Fort UNION No. 2, OR UPPER LEBO
The great bulk of the collection is from these beds. The Silberling
and Gidley Quarries are described and their fauna listed in a separate
section of this work. The other No. 2 localities with identifiable
mammals are as follows:
Loe. 61.—Sec. 24, T. 4 N., R. 15 E. This is one of the richest of
surface localities but has yielded no fossils in place. It is in the valley
of Wildcat Creek, west of the stream, about 75 feet above the base of
the No. 2 beds. The identifiable mammals are:
Eucosmodon sparsus: Lower incisor.
Ptilodus ?montanus: Broken premolar.
Mimotricentes angustidens: 2 isolated lower molars.
Metachriacus provocator: Associated upper and lower teeth, 2 isolated lower and 2
isolated upper jaw fragments.
Metachriacus sp: Upper tooth.
Didymictis cf. haydenianus: Broken lower premolar.
Ellipsodon aquilonius: Lower jaw.
Litaletes disjunctus: Fragment of lower jaw and atypical but probably referable
upper jaw.
Tetraclaenodon cf. symbolicus: Upper tooth.
Anisonchus sectorius: 4 lower jaws.
Loc. 8. —Sec. 23, T.6 N., R. 15 E. The exact horizon is uncertain,
but the locality is near Loc. 81 and probably at about the same or a
somewhat lower level. The only identifiable fossil is a partial upper
jaw of Didymictis haydenianus.
Loc. 24.—Sec. 2, T.3 N., R.15 E. This is near Loc. 25, about halt
a mile farther southwest, near the shore of Lake Adam, and at about
the same level, about 300 feet above the base of the No. 2 beds. The
identifiable mammals are: Associated upper and lower teeth of Meta-
chriacus provocator, upper tooth of Didymictis microlestes, one upper
and one lower jaw of Anisonchus sectorius.
Loc. 25.—Sec. 35, T. 4 N., R. 15 E. Near the north end of Lake
Adam and about 300 feet above the base of the No. 2 beds. This isa
rich locality that yields surface material on every visit, but only one
specimen has been found in place and attempts to develop a quarry
have so far been unsuccessful. The following have been found:
Eucosmodon sparsus: Lower incisor.
All known material.
See systematic descriptions.
Five specimens.
Metachriacus provocator: 4 lower and 2 upper jaws (in American Museum).
Tetraclaenodon symbolicus: 9 lower and 1 upper (the upper and 4 lower in the
American Museum).
Anisonchus sectorius: 3 lower and 1 upper (the upper in the American Museum).
Loc. 60.—Sec. 9, T.3 N., R.15 E. This is the southernmost local-
ity in the field, southwest of Lake Adam. The horizon cannot be
closely determined but is near that of Loc. 25. There is a large but
Deuterogonodon montanus
? Deuterogonodon sp.
38 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
almost barren exposure at a small pointed hill and east of this a flat
and poor but richer exposure where the following mammals were
found:
?Ptilodus gidleyi: 1 lower premolar.
Ptilodus montanus: 2 lower premolars.
Metachriacus provocator: Associated upper and lower jaw fragments and 1
isolated lower.
Anisonchus sectorius: 1 lower jaw.
Loc. 81.—Sec. 23, T.6 N.,R.15 KE. This isin the extreme northern
part of the field where the steep monocline swings into the Widde-
combe Creek Anticline. It is in the lower half of the No. 2 beds,
probably about 300 feet above their base. Mr. Silberling found this
excellent shale exposure years ago, but nothing was found in it until
1935, when a small rich pocket of fossil mammals, most of them still
in place, was discovered. Extensive prospecting failed to uncover
anything else, and despite its richness this seems to have been a very
local pocket, only 2 or 3 feet in diameter. The material is in the
American Museum collection and includes the following forms:
Aphronorus fraudator: Upper premolar.
Prothryptacodon ?furens: 1 lower jaw.
Metachriacus provocator: 1 upper and 3 lower jaws.
Mimotricentes ?latidens: 1 upper and 1 lower jaw, possibly associated.
Didymictis ef. haydenianus: 1 upper jaw.
Loc. 52.—Sec. 23, T.5 N., R.15 E. This locality is at a large shale
exposure immediately north of the Gidley Quarry. Fossils have been
found here at two levels, one about the same as that of the Gidley
Quarry and designated as Loc. 54, and the other, Loc. 52, about 50
feet lower. Numerous scraps have been found here, but the only cer-
tainly identifiable specimen is apparently associated right and left
M, and other fragments of Claenodon montanensis.
Loc. 4.—The Gidley Quarry occurs at this level relative to the other
localities. It is discussed elsewhere.
Loc. 5.—Sec. 33, T. 6 N., R. 16 E.
Loc. 6.—Sec. 34, T. 6 N., R. 16 E.
localities, where Douglass found the first Fort Union mammals in 1901.
They are at nearly the same level, about 1,200 feet above the base of
the Fort Union (No. 1), and 125 to 150 feet below the basal No. 3
sandstone, about the same level as the Gidley Quarry. Loc. 5 is a
relatively large shale exposure on the west side of Bear Butte near its
northern end, readily recognized as being opposite (across the county
road from) a small, tepee-shaped outlier of the main butte. Loc. 6 is a
smaller shale exposure about quarter of a mile northeast of Loc. 5 and
just east, or slightly southeast, of the extreme northern end of Bear
Butte (see plate 3). Douglass’ material from the two localities (with
identifications slightly amended in the light of later knowledge) was as
follows:
These are the two discovery
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 39:
Tetraclaenodon cf. puercensis: 3 isolated upper teeth.
Ellipsodon aquilonius: Jaw fragment with Mbp.
Anisonchus sectorius: Jaw fragment with Py and M,.
Pantolambda spp.: Canine, premolar, and limb bones, perhaps of more than one
species.
Subsequent discoveries at Loc. 5 include an unidentifiable multi-
tuberculate and other fragments, and at Loc. 6 the following:
Conoryctes cf. comma: 2 upper molars.
Tetraclaenodon cf. puercensis: Upper jaw with dm!-M}!.
Pantolambda sp.: Worn and broken upper molar and limb fragments.
Loc. 54.—Sec. 23, T.5 N., R. 15 E. This is immediately north of
the Gidley Quarry and at about the same level, on the same exposure
as Loc. 52 but about 50 feet higher. The most nearly identifiable
specimens found here are an isolated lower tooth and limb bones of
Pantolambda sp. The rich pocket in which the Gidley Quarry is
developed apparently does not extend this far north.
Loc. 1—The Silberling Quarry is the highest mammal: locality
definitely in the No. 2 beds and occurs at this position relative to the
other localities. It is discussed elsewhere.
Loc. 3.—On line between secs. 11 and 14, T.5 N., R. 15 E. The
horizon of this locality has not been determined, but it is in the upper
part of the No. 2 beds. It has yielded only one lower jaw of Tetra-
claenodon symbolicus.
Fort UNION No. 3, OR MELVILLE
This great upper division has numerous scattered localities, but
only one (the Scarritt Quarry) has yielded a fauna that can be con-
sidered of much value. The first two localities here listed, 15 and 70,
are definitely in the No. 3 beds, probably in their lower part, but of
unknown relative level. The others are here arranged in the order
of their stratigraphic levels.
Loc. 15.—Sec. 9, T.5 N., R. 14 E. The only identifiable specimen
from here is a lower jaw fragment indistinguishable from Paromomys
maturus. The level is uncertain but is above the basal sandstone of
the No. 3 beds.
Loc. 70.—Sec. 31, T.6 N., R. 15 E. The only specimen from this
locality, also in the No. 3 but of doubtful level, is a lower tooth prob-
ably of Tetraclaenodon, but possibly Gidleyina.
Loc. 82.—Sec. 11, T. 4 N., R. 15 E. There is some doubt about
this locality, as the local section is not clear, but it is probably near
the base of the No. 3 beds. The only identifiable specimen is asso-
ciated M? and broken M® (Gn the American Museum) referable to
Tetraclaenodon cf. puercensis.
Loc. 58.—Sec. 14, T. 4 N., R. 15 E. This locality is immediately
adjacent to Loc. 82 and at the same level. It has yielded one upper
tooth of Claenodon cf. feror.
119212—37-—4
40 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Loc. 39.—Sec. 15, T. 4 N., R. 15 E. This locality is also near the
base of the No. 3 beds, and at about the same level as Locs. 82 and 53,
possibly a little higher. Here were found a lower jaw fragment of
Claenodon cf. ferox and limb bones probably of a pantolambdid.
Loc. 12.—Sec. 30, T. 6 N., R. 15 E. This locality is adjacent to
the next, Loc. 27, and at a slightly lower level. It yielded an upper
jaw of Anisonchus sectorius.
Loc. 27.—Sec. 30, T.6 N., R. 15 E. This and Loc. 28 are at about
the same level, 300 to 400 feet above the base of the No. 3 beds, on
opposite sides of the Harlowton—Melville road where it turns after
descending the ‘‘Fish Creek Hill.” 1! The type material of Gidleyina
silberlingi is from here.
Loc. 28.—Sec. 29, T.6 N., R. 15 E. A little less than quarter of a
mile northeast of Loc. 27 and at about the same level. It yielded an
upper tooth of a pantolambdid and one identified as cf. Conoryctes sp.
PRINCETON LOCALITIES
Under this general heading I group numerous localities in the
western part of T. 5 N., R. 15 E., and two in the northeastern part
of T.5 N., R. 14 E. The exact localities are given in the serial list
andonthemap. These localities were found and worked by the Prince-
ton parties under Farr in 1902 and 1903 and were thoroughly pros-
pected at that time, the surfaces apparently very well cleared. Mr.
Silberling, Mr. Silberling and I, and the Third Scarritt Expedition
have at intervals between 1903 and 1935 gone over these localities
again, but they have not yielded much new material. In the past
few years their surface conditions have been increasingly unfavorable
for collecting. Mr. Silberling’s system of locality records was not
initiated until several years after the Princeton work, and the locality
records of the 1902 and 1903 collections, at least as they are now pre-
served, are very vague and not entirely reliable, especially as these
parties also collected much material in those years at widely different
levels in other parts of the field. There are a number of identifiable
mammal specimens in the Princeton collections that can be definitely
placed, on the basis of such records as are preserved and of Mr.
Silberling’s certain recollection of particular specimens, in a cluster
of localities all at about the same level. Two more are possibly from
this general area and level, but not definitely placed. The others
(eight cataloged specimens) are surely or probably from quite different
levels and localities and are mentioned elsewhere.
Locs. 36,.38, 40, 41, 42, 48, 45, 57, 59, 60, and 68.— All in secs. 17,
19, 20, and 29, T.5 N., R. 15 E., all Princeton mammal localities, all
at approximately the same level, stratigraphic differences probably not
over 100 feet (which is generally insignificant in this field) and are
ll As the road was until 1935, at least. Its course may be changed by work then in progress.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 4l
about 900 to 1,000 feet above the base of the Fort Union No. 3 or
about 2,250 to 2,350 feet above the base of the Fort Union No. 1.
The following Princeton material seems definitely to be from this
group of localities.
Gidleyina montanensis: Type, as described below; this is from Loc. 68.
A lot including ?Gidleyina sp., lower premolar, a lower molar of an indeterminate
oxyclaenine, and 3 probably associated lower teeth of Anisonchus sectorius,
all probably from Loc. 42.
A badly broken lower jaw with 3 imperfect teeth, suggestive of P. cavirictus but
not that species, perhaps not that genus, probably from Loc. 43.
Gidleyina ?montanensis: A miscellaneous lot including an M? probably of this
species; an isolated Py. These are probably from Loc. 60.
The only approximately identifiable specimen now in the National Museum and
labeled as from these localities, a lower jaw fragment from Loc. 57, probably
Gidleyina sp. but possibly Tetraclaenodon.
Loc. 44 is at a slightly higher level than those just discussed, prob-
ably about 200 to 300 feet. It has yielded a large lot of probably
associated material of Claenodon ?feror and also an upper premolar
probably pantolambdid but not Pantolambda. Both lots are in the
Princeton collection.
Locs. 20, 61, 62, 63, 69 and 72 are also Princeton localities and have
yielded mammals, but I have been unable definitely to tie in any
identifiable specimens in the collections to these localities.
Loc. 56.—Sec. 13, T. 5 N., R. 14 HE. This is the Scarritt Quarry,
which occupies about this position relative to the other localities here
listed. Its fauna is discussed elsewhere.
Loc. 18.—Sec. 14, T.5 N., R. 14 E. This locality is nearly a mile
west-southwest of the Scarritt Quarry, over a gentle hill (running
north from Cayuse Butte), and at nearly the same level or perhaps a
little higher. Gidley recorded it as ‘about 2,000 feet below the top
of No. 3”, and my estimates would place it at just about that distance
stratigraphically below the highest exposures on Porcupine Butte.
It has yielded a pantolambdid upper tooth, a lower jaw of Anisonchus
sectorius, and a lower jaw fragment of Ellipsodon sp.
Loc. 11 —Sec. 23, T. 5 'N., R. 14 E.
Loc. 138.—Sec. 22, T.5 N., R. 14 E.
about half a mile apart at their ends and are in different sections, they
are merely two parts of a series of shale exposures and blow-outs.
Material from the two marked localities has not been consistently
separated, nor is there any great need for doing so since they are at
about the same level and in a more or less continuous series of expo-
sures. They are high up on Cayuse Butte, or Cayuse Hills, on the
divide between the Sweetgrass and Fish Creek drainages. Mr.
Silberling has found numerous fragments on the surface here, and in
past years the exposure has been good, but in 1932 and still more in
1935 we found it in poor condition, covered with wash and in places
Although these localities are
42 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
tending to sod over. Efforts have been made to find a bone level or
develop a quarry, but so far no material has been found in place.
This series of exposures is important as the highest in this field from
which identifiable material has been recovered. The level is about
3,000 feet above the base of the No. 3 beds. The National Museum
specimens available are:
Plesiadapis rex: Type and referred material, as described below.
Cf. Paromomys, genus and species undetermined: An isolated upper tooth.
?Gidleyina superior: Type lower jaw.
Teiraclaenodon sp.: 2 upper molars.
To this list may be added the following forms in the Princeton
collection. Their derivation from this level seems to be established
with sufficient probability:
Multituberculate undetermined: 2 broken premolars.
Elpidophorus ?patratus: Lower molar.
Claenodon cf. feroz: 2 upper teeth.
Thryptacodon cf. australis: Lower molar.
Hyopsodontid aff. Haplaletes: M?-3.
Loc. 49—NWYNW*Y, sec. 23, T. 5 N., R. 14 E. This is near
Locs. 11 and 13 in position and also stratigraphically. According to
Mr. Silberling, Princeton no. 13756, numerous tooth and jaw frag-
ments of Claenodon ?ferox, came from here.
Loc. 66.—Sec. 14, T.5 N., R. 13 E. This is a very high exposure,
at least 750 feet stratigraphically above Loc. 13, on the east flank of
Porcupine Butte, about one-third of the way up that butte. It isa
small shale exposure, important only as the highest level in this
field where mammal fragments have been found. It is also con-
siderably the most western mammal locality in the field. The
material collected was, Mr. Silberling informs me, definitely mamma-
lian, but probably was not identifiable and no specimens bearing this
locality datum were found in the collection.
HorIzoN UNCERTAIN
Here may be mentioned two Princeton specimens that are of too
uncertain provenience for present inclusion in the more precise lists
or for use in correlation.
No. 14191 includes two upper molars of a small Claenodon, com-
parable to C. silberlingi, collected July 3, 1903, labeled as from the
Torrejon, “‘Anderson’s Big Timber Road”, a designation too vague
to indicate any particular horizon or locality.
No. 13757, December 1902, ‘‘Loc. No. 9 Puerco’, is probably from
the Fort Union No. 1, since the No. 2 was known to be of Torrejon
age by the Princeton parties and the No. 1 considered as Puerco.
Loc. 9 of Silberling’s series is in the No. 1, but since the Princeton
parties did not use these numbers this is probably only a coincidence
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT.
and the locality is uncertain.
43
The specimen includes M!~? appar-
ently of Tetraclaenodon and comparable to JT. symbolicus, but not
close enough to assure specific identification.
TABLE 2.—Serial list of localities, Crazy Mountain Field, Mont.
No. Quarter Section
se ee INTE Of SIWis=-—ee 4
7 ae NE half of NE quarter__ 7
x as SoA On line, near corner | 11-14
with 10 and 15,
eae NDWeof Nils e een 23
| eee SIR OS Hasan ee eee 33
Geese INGEN OLS Wiesenes ee ee 34
Uacpseee| Ga a 25
Sriteee 2 Near middle of east half_ 23
5 at a SHrotiS He s2s5= 2 tales 35
1OQue ass 4% mile south of north | 15-16
section lines.
1G aes SIWLOP SiIWietes2 22-222 o=- 23
io eeeeee FSH Dy a Be pS aed Ce Sep heed 30
1S SWEOnsihia-a2 2022-8. ee 22
4s Soo Same as Loc. 3__..-.---- 11-14
ilies IN(MrolSiWeeee--- aoe 9
1G iee3 INGO OCS ee eS 34
ly foes ahas SiRofeNiie sees 22 eres 15
18io ING Witolioios-=6— eee tks 14
> Us ER Se INGE OLINGH < fae eee 15
20 res INGE Of INR ee rs 13
eee | ee 2k ER ee See SS 16
77) SINAN) GEST fee Be 34
9A} eae Near middle of east half- 8
ami ae st INIWROLOINI Woe = 2 222 2
2h meee TS WrOlObes- oo sweet 35
2G eres | Re ee es 31
Pe sa INIEOR Shee ee ce eee 30
S28 Sees INIWHOfS\Wessees eee 29
Vs ae ING Win OfINIWiese nee 29
SOs == INGW ena eee ene es 30
ie ee eee 26
SUA es Sel Ree ee eae Cee 25
ahaa ee S\Wik oes ee ees ee 17
Sib en 2e |e eee ee See 36
BH eee INA Oy COS HIS) De eee eee 33
OOnse es Near center of north line_ 20 |
3 ee INDO IS De eee es eee 33 |
ACs Se 8 SIM OfNiWee ee eee 17
3}! Eee SIP Gt Shite ene ae eee 15
40 SAWVMOLINIW see e a ee 29
CT SINOfNiWettee ae ee 29
Ab INGROLN Wiese ee aoe ee 20
CRW eee INIWVOLANI Wenn =e ana 20 |!
Town-
ship
North
oom ao
oo
ome On ons oon Oo AAAMWMD FP WON
oro on
Feet above
base of Fort
Union No. 1
(In No. 2)-_-
(In No. 2)---
1,200. = 2-22 —2
(In No. 2, a
few feet be-
low Loc. 3)
(In No. 3)-.-
(In No. 3)_--
(In No. 3)_--
(In No. 3)---
(In No. 3)---
KOOTENAI_-_
(In No. 3)-_--
Remarks
SILBERLING QUARRY.
“Various.”’
Ses faunal list.
GIDLEY QUARRY.
See faunal list.
Do.
(Not relocated—not a fossil
locality).
See faunal list.
Do.
Mammal fragments.
See faunal list.
Do.
Do.
Mammal and other frag-
ments.
See faunal list.
Invertebrates and mammal
fragments.
Invertebrates.
See faunal list.
Mammal and other frag-
ments.
Invertebrates and Clcenodon
(fide Silberling).
(Not relocated.)
brates.
Plants.
Footprints, plants.
See faunal list.
Do.
(Not relocated.) Plants.
See faunal list.
Do.
Invertebrates.
Champsosaur and mammal
fragments.
(Not relocated.)
brates.
Do.
Invertebrates.
(Not relocated.) Plants.
Plants.
See “‘Princeton Localities.”
Plants, invertebrates.
See ‘‘Princeton Localities.”
See faunal list.
See ‘‘Princeton Localities.”
Do.
Do.
Do.
Inverte-
Inverte+
44
BULLETIN 169, UNITED STATES NATIONAL MUSEUM
TABLE 2.—Serial list of localities, Crazy Mountain Field, Mont.—Continued
No. Quarter
7 ee SH chiS Mulan soaks oe
Yu el SE of SW of SW--------
46. 22-23 8) NAW Of Ni Wels eee ce ese
A fest ces © INGEVOTONID) -=----22 228522
ARE so INI eae oe eae eae
CAS paps pag ies NGWiotN Wee. ee
50a Near middle of south
half.
Biles see SiWeweeeone ose sasewes
Hotere eA INIWi OLN Be 2s0025282222=
ies NW of NW of NW-----
patra INSWOfsN Rie. eseecss-
bosesese= INI Wess eet aat eee
DOesee os SIRSOLN IW. 2 ae oe oe eee
iiyfeee oe SiIWronSie e222 22 32
Lia ee Near center line in north
half.
S9l A Wastnaltse. 2. ae k
60S Se SE of NW of SW...-----
(ee See ett) Fe erecta
622222222 SiWokSiW 222222252458
63a ING Wp eat os See ae
(yee SIWik ete 2 eee
(fe ee SEtopSiw--=----ses5->=-
662-5 SIWe eissae 22 eee ces
(Gla see SiBoLS Bi... sete se2S
68oeann Near center of north line-
(es SiWirie tof ee 2 eee Ree
Omen Near middle of east half_
(ieee Se MOR TOtS Mice soc see ose ce
(pe ee Near middle of north
half.
ome INGE OLS Wi22 i eseseeces
(4 sets INJBVOLIN IN 22 Soe sence ae
(pee SiWite 2 oe nee eee
Ol. Saas SWaot(Sib 222 S-- ae sane
Tesaee INiBiseset. see aoes
yee SIWNOLS Wie = a- ese e-se2-
ih eee A Ti) DORE ea pee et
SOLES: ING ae eons or Se
Slyeeey Near middle line in
south half.
S22e res SW of SW of SW-------
Town-
Section! ship ae
North
a 5 15
17 5 15
24 5 14
10 5 14
25 5 14
23 5 14
9 3 15
24 4 15
23 5 15
14 4 15
23 5 15
29 5 15
13 5 14
V7, 5 15
20 5 15
20 5 15
19 5 15
1 5 14
7 5 15
18 5 15)
34 6 16
26 6 16
14 5 13
10 5 13
20 5 15
18 5 15
31 6 15
36 6 14
12 5 14
34 6 16
15 5 15
6 4 16
11 5 15
32 5 15
26 6 16
10 5 13
14 5 13
23 6 15
11 4 15
Feet above
base of Fort
Union No. 1
GngNios3)2=2
(In No. 8)---
@mn.No:'3) 22.
2,500 See
O;B00 22825 52=
(In No. 3)---
(In No. 3)---
(In No. 3)---
1,350 22 es25=5
(Lower part
of No. 2).
(Lower part
of No. 2).
(In No. 3)---
(High in No.
3).
(High in No.
Remarks
See “‘Princeton Localities.”
Do.
Invertebrates.
Plants.
Do.
Mammal fragments.
See faunal list.
Do.
Do.
Do.
Do.
Invertebrates.
SCARRITT QUARRY.
See ‘Princeton Localities.’”
Invertebrates.
See ‘Princeton Localities.”
Do.
Do.
Do.
Do.
Mammal fragments.
See faunal list.
Do.
Plants,
tiles.
See ‘Princeton Localities.”
Do.
See faunal list.
Mammal fragments.
See ‘‘Princeton Localities.’”
invertebrates, rep-
See faunal list.
Fish.
Mammal fragments.
Do.
Do.
See faunal list.
Champsosaur.
Plants.
See faunal list
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 4h
INDEX TO LOCALITIES BY SECTION NUMBERS
Townsuipe 5 Nortu, RANGE 13 East
Section 10: Locs. 67, 79. Section 14: Locs, 66, 80.
TOWNSHIP 5 NORTH, RANGE 14 East
Section 1: Loc. 61. Section 15: Loe. 19.
Section 9: Loc. 15. Sections 15-16: Loc. 10.
Section 10: Loc. 47. Section 22: Loe. 13.
Section 12: Loc. 72. Section 23: Loes. 11, 49.
Section 13: Loes. 20, 56. Section 24: Loc. 46.
Section 14: Loe. 18. Section 25: Loe. 48.
TOWNSHIP 6 NoRTH, RANGE 14 EAstT
Section 36: Loc. 71.
TOWNSHIP 3 NORTH, RANGE 15 East
Section 2: Loc. 24. Section 9: Loc. 50.
TownsuHip 4 NorRTH, RANGE 15 East
Section 14: Loes. 53, 82. Section 24: Loc. 51.
Section 15: Loe. 39. Section 35: Loc. 25.
TOWNSHIP 5 NorTH, RANGE 15 EAst
Section 7: Locs. 44, 62. Section 19: Loc. 60.
Sections 11-14: Loes. 3, 14. Section 20: Loces. 36, 42, 43, 58, 59, 68.
Section 11: Loc. 76. Section 23: Loes. 4, 52, 54.
Section 15: Loes. 17, 74. Section 25: Loc. 32.
Section 16: Loc. 21. Section 29: Loes. 40, 41, 55.
Section 17: Loes. 33, 38, 45, 57. Section 32: Loe. 77.
Section 18: Locs. 63, 69.
TOwNsHIP 6 NorTH, RANGE 15 EAST
Section 23: Locs. 8, 81. Section 31: Loc. 70.
Section 26: Loc. 31. Section 34: Loc. 16.
Section 29: Loes. 28, 29. Section 35: Loe. 9.
Section 30: Loes. 12, 27, 30.
TownsuHIP 4 NortH, RANGE 16 EAst
Section 5: Loc. 75. Section 7: Loc. 2.
TOWNSHIP 5 NORTH, RANGE 16 EAST
Section 4: Loe. 1. Section 8: Loc. 23.
TOWNSHIP 6 NORTH, RANGE 16 EAst
Section 25: Loc. 7. Section 33: Loes. 5, 35, 37.
Section 26: Locs. 65, 78. Section 34: Loes. 6, 16, 22, 64, 73.
Section 31: Loc. 26.
TOWNSHIP 7 NORTH, RANGE 16 East
Section 36: Loc. 34.
46 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
FAUNAL SUCCESSION AND CORRELATION
COMBINED FAUNAL LIST
Table 3 lists all the genera and species of mammals so far identified
in this field, with the approximate level in the Fort Union series at
which each is known to occur. The only omissions are a few speci-
mens of uncertain level. They include no forms not otherwise recorded
here but might have extended the vertical distribution were their
horizons accurately known.
The list incidentally emphasizes the extraordinary richness of this
field and its known faunas. It shows the presence of 51 genera (5
tentatively identified, but different from the 46 definitely known) and
79 species (15 tentatively identified or now nameless, but different
from the 64 definitely known and named). The field is richer in
variety of fossil mammals than the Puerco and Torrejon together,
indeed almost as rich as all the other North American Paleocene
combined.
The figures given for each column are the approximate stratigraphic
levels in feet above the base of the Fort Union No. 1. In the 575
column, fossils from Loc. 51 are listed. The 800 column includes
Locs. 24, 25, 50, and 81. The 1,150-1,200 column includes Locs.
5, 6, and 54 and the Gidley Quarry. The 1,265 is the Silberling
Quarry. The 1,350 includes Locs. 35, 53, and 82, and 1,700-1,750
is Locs. 12, 27, and 28. The ‘Princeton localities’? are included in
the 2,250-2,350 column, and Loc. 18 and the Scarritt Quarry in the
3,300-3,500 column. The last column, 4,350, is for Locs. 11 and 13.
TABLE 3.—Combined faunal list, Crazy Mountain Field, Mont.
No. 1 No. 2 No. 3
a (At | 575 | g00 [1150-11 965 | 1,350 |1:700 | 2.250-|3,350—) 4 359
level | feet | feet | 1 feet | feet | 12750 | 2,350 | 3,500 | “foot
shown) feet feet | feet | feet
Feet
PHIOUUSIINONLANUS Ae men ae ae oe eel ee x x x x
PPGlOdUSdOUgIASSt ae a ee eee | Baers ole ee x x
PPiilodus gidleytetssss fen ON ea ee ees |e >.< axe
CELOMUSISINCLOhIn =a eee ae eee Bilis PS ae x d.«
Plodussp22- 2.2522 oe ee OE ee alle UE re x
PECLY DOCUSIOTONG CT Ie a ae ne ee ee | ee ene | ene a | eee x
PEclypodus 7ussella=_ aoe+ a2 eS | ees SE ee x axG
Pictypodus silberlingi= oe ss eee | ea | x
PUCLYDOGUSINAUNLET I sae See ee a en | oe eee || ee ee ee ee | ears a xX
PE OTECLY DOGS TED SCM tare a eee ee | ee ee eee x |
ERUCOSTOGOMEPOTSUss2 2. nese ee eae xX DG al (See ee |e O.S
CQELASLODS DAT CUS rea eee ee ere | ee ee | eee ee x x
Prodiacodon' concordiarcensis.._...--._|_---& = -a\e. 2. |e _= x
UGepla codon laddese soe ane eee ee ee eee eee x
Leptacodon muntuscultm.-—_----- 2-2 |2o--- |) no ne xX
ieptacodonictl.tenenprcs 2. ate soe tes nae cones ce eal ceeeee (eee a ee eee |p eel eee | eae x
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT.
47
TABLE 3.—Combined faunal list, Crazy Mountain Field, Mont.—Continued
No. 1
Species
Feet
Myrmecoboides montanensis - ._..-----|--------
Stilpnodon simplicidens.._.....-.-.-.--|--------
Bessoecetor diluculi
OPER GITEOSITLOPUIS Peete ses oe ee eee eee ee
PA DRTONOTIULS |RAUGQLON- = oe ene ene oe oo
Eudaemonema cuspidaia._....--------|--------
Elpidophorus patratus_—2.....-.------|=--..---
UDIODROTUSLININ OF an ae eee eae eee ee
ACTOUIR SILUCNIVILG Pattee nee ee | ee
CU CHANIGASA pics re ae eee a ene | ae ee
‘Pronothodectesmatthewt: = 2 s225=.2222| ees
IPlestadapis AnCepss na. 3. sama nono nee | ee eee ae
PleSiQdA TSI er oe eee = eens cna e eee a | sees eco aL Betas
Pl DhidOLansruslOnenCihe=-= s— =~ - see won| pe oee ne Ae ee
Carmolanies N@zelaes == - sane aaa ae [onan ee eee
FPOTOMOMPSINACUILUS T= onan eee ee | eee nee eee
Paromomiysidepressidens. == 2. 52 eae
Cf. Paromomys, genus and species
Nd eLanmined' = _ hav canes ca seases|soescess|peeess
IPOlOCCRthONAUICUSDIS oe a oe onan eal aoa a= | sateen
PPAlenOChih@uliNOlraae 22 noe ee en ee| ba nessa | seen oe
PRENACOleMUT TUG WONUS 228 Soe cee ono eee | oo
Conory Ctes|COMME= sa 2 = 35-5 --ee==-=|---55-+= |e = =8
@iAConoryctesispeio2- = oo 5 2 2255252) BIL LS
Psittacotherium multifragum........--|--------|------
CIAENOCONIMONTANENS1S so sae = aaa ee ea ee aeee eee
ClnenodonisilberUinginn oes ase oO eee ae
Claenadoniiatidens== >. * ees =e eee | ee
GClaenodon’ terror sto... ssa ane ace sseen)| 2 2ebons sacs
Claenodonisperes2: sos 2s=- 222 scent ase |ecteess|oocaes
Deuterogonodon montanus--.......---|----.---|------
PDCULENOGONOGONISDi2 = = seen ae eee eae ee ee nee
IPT OUT DLACOCONYUTENS =e canoe oe aoe oa ees oe eee
Prothrypiacodon, (/Urens = === -<o-s5-|--s--se5|snree
RETUMLACOCON PAUSLTOUNS ss eee ees nee ee eelon aoe eee eee eo tee se | See eee Eee Eee e
ChriacuspDUugnOr seo noe ne
WiiChmacwus Spi. a sees cee seuss [PS es eel eee
Metichricus: Dunitortoc.cke-ceseee sa |S S22 =| eos -
Metachriacus provocator=.—...---.-----=|¢=---.--
WMetachriacusispa a 2osaenac anes eeee = pee eess
Spanoxyodon latrunculus--..-...-----|--------|------
SIVIAIROUTICONLES LALICENS ae ee ne ae | Seen eae
MGM Oni CentesvelQliden sas seme eee oe nee eee
Mimotricentes angustidens.__..-------
RINALNOUTICENLES SDs aene ee pease eee 300
Didympcris MicrolesteBes ae oe a eae eee | Sane eee | aaa ee
DOU IMICHSILEN TS ane aes oe acne | oe ee
Didymictis ?haydenianus._......------|--------
chido PADDUSIMUSLELTMUS onan oe een ae | eee eee | pee
Dissacus Spt Les eis cee AP ase E Ses seal es ets
FV MsOdOnaguiloniue. eee oa eee eae ee
EellinsodomSD = -2-- Sea tes oe ae |e aeeee tea SS
Ditaletesdisjunciniss a2 >. 2 Sees eaten
No. 2 No. 3
!
1,150- 1,700-| 2,250-
La ih ON fare 1,350 | 1,750 | 2,350
feet feet | feet
ufeles a) x
Nanas x
ei el
5) HR 1 | aenele ns oa ne tte
dana Ke fx
ee ee x
ieee oe
nee axe
ss Xx
ER Eee x xX
ieee xX
pas aXe X
aefs 1 Xe
foe sees! Xe x
Pomel [er Wes MEDOAN eer x
Ses Ae x
A See aXe
ee mS x
peeve. XS
EW. SEE ER en ereeacd XK LCS Xe
ie as Xe
x
x
Lee >:€ ox
x
a eECY x Exe
x
Aa a) eh ee x
eared x
vay ees aXe
>, Sei ees >.€
LER notes IX
aXe x ax
asl x
XG Cee | x
Lae: x
Stee xX Xx
oo ee aXG Xe
aX
3,350- E
00 | a
feet
x
x
x xX
x
x
pees xX
x
poe xX
x
See Sse x
4
x
x
48
BULLETIN 169, UNITED STATES NATIONAL MUSEUM
TABLE 3.—Combined faunal list, Crazy Mountain Field, Mont.—Continued
No. 1 No. 2 No. 3
Species 5
: revel | 25 | 800 | 7599 | 1,265 |1,350 | 772) | 35%) [329 | 4,350
shown) feet | feet feet feet | feet feet | feet | feet feet
we
Feet
LALO MY US CISSENLONEUS= a sa snes neo e ee |e ee oe x |
Eloplaletesidisceptatnine. 22428 cee e | | ae x |
CLibaplaletes'Sp ase an tes kan an ee Pesos Alans Ai HL Bele Cee oe NE ee fexse fe yoann x
Hitolestes.motissimius: 2. 2222) sae Wal owe a [a ea | ee Se eecese x
Tetraclaenodon symbolicus...------.--|_...--__|__--_- am EUR xg |
Tetraclaenodon ef. symbolicus .._..-__- 300 | X
Tetraclaenodon' ci. puercensis.- -—--224|2 222. a e- | oc - oe EX Alsen x
REtTACLACNOG ONS) D eee =e a ke | ee rc tonmen | (Sg fae ee | oe | sede oe | ee x x
Gidleyinavmontanens7s Cae ert ee | SAEs | reed 0A | CRON Sel (pat Sede ea eae xX
PGidleyinarsilberlingisse. sete tek ran cee I ee olla Ae ee | Ae ete ae oe x
PGCIGLEUITIORSU DETt Once es eee tes ae eel | Coe wee | he kN en | ee eee ae SNE es pares Sie x
PGidleyiNna Spy Sse es Se SSE ee a UE ee A Eine es 2
Cori PRAGUSMNONIANUS 22 ton ee ane ane ee oe a x x
Anisonchus'sectorius-_. 2.2.20 2-3-} 55.222 22 >.< x SKA | eer dl eee x x
Pantolumod@UnterMedius sans nae aa ee ee | eee el x
PPantolambdarsp 3 35 ewer see | hee oly oe red x
Pantolambdidsundetermined <.4-.2-|2 =| ee eee Xe xX x x
FAUNAL SUCCESSION
The No. 1 beds have yielded only ?Ptilodus sinclairi from near the
base; Clacnodon vecordensis, Chriacus pugnaz, ?Mimotricentes sp., and
Tetraclaenodon ?symbolicus from near the middle part; and Mimotri-
centes angustidens from the top. The first and last of these forms are
inseparable from species occurring well up into the No. 2, and so is
Tetraclaenodon ?symbolicus. Claenodon vecordensis and Chriacus
pugnax are distinct species but cannot be considered to be clearly
ancestral to anything known from the No. 2. The evidence is inade-
quate to demonstrate either occurrence or absence of distinct faunal
advance within the No. 1-No. 2 series. It does suggest, however,
that such advance must have been relatively slight and that it was
probably of less than generic rank, if it occurred. The data definitely,
if not altogether conclusively, oppose the hypothesis that the difference
between No. 1 and No. 2 faunas can have been as great as between
Puerco and Torrejon.
Within the No. 2 beds the first important point is that the Gidley
and Silberling Quarry faunas are identical in degree of evolutionary
progress and show no significant difference in age despite a small
difference in level, about 65 feet. There are 23 species definitely
identified in the Silberling Quarry. Seventeen of these also occur in
the Gidley Quarry and, as shown-in the systematic descriptions, these
suggest no difference, even of less than specific rank, between the
forms in the two quarries. Four Silberling Quarry species do not
occur in the Gidley Quarry but do occur at lower levels, so that their
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 49
absence in the Gidley Quarry is not due to time differences but to
facies or accidents of discovery. These species are Hucosmodon
sparsus,” Mimotricentes angustidens, Didymictis haydenianus,” and
Tetraclaenodon symbolicus. Only two species, Psittacotherium multi-
fragum and Elpidophorus minor, known only from one specimen each,
are confined to the Silberling Quarry, and there can be no doubt that
this is the result of chance. The Gidley and Silberling Quarry
faunas are, then, a unit as far as appreciable differences in time are
concerned.
The 575-foot level is represented by eight definitely identified
species, of which seven also occur in the Gidley or Silberling Quarries
or both, and the other, Metachriacus provocator, reappears at the
800-foot level. The 800-foot localities have 10 definitely identified
species, 8 of which also occur in the Gidley or Silberling Quarries or
both, while Deuterogonodon montanus is confined to this level and
Metachriacus provocator appears also 225 feet lower. All the material
of Deuterogonodon montanus is from a single locality, and it must be
considered as a sporadic and chance occurrence with no probable
validity as an index of time relationship, particularly as no probable
or possible ancestral or descendent forms occur in this field. The
distribution of Metachriacus prevocator is peculiar. It is relatively
very abundant at No. 2 levels below the Gidley Quarry, being the
only species that occurs at all these localities (except for Loc. 52,
which is only 50 feet below the Gidley Quarry and must be considered
as at essentially the same level). At the Gidley and Silberling Quarry
levels it has not been found, but an allied species, M. punitor, is
present and fairly common. WM. provocator is the larger and in some
other respects probably the more specialized of the two species,
despite its earlier appearance. Thus the relationship is not that of
ancestor to descendant, and no temporal difference is demonstrated.
The facies of these earlier localities are demonstrably quite different
from those of the quarries, and the most reasonable conclusion is
that the distribution of the two species of Metachriacus is conditioned
by facies and not by time.
It thus appears that the whole Fort Union No. 2 shows no probable
significant faunal advance and that it forms a unit as far as time and
correlation are concerned.
It is particularly unfortunate that the three lower fossil zones of
the No. 3 beds are represented by few and poor specimens, for this
is a crucial point in the sequence, probably covering (as shown under
“Correlation’’) the transition from Middle to Upper Paleocene. The
lowest level, 1,350 feet, yields Claenodon ?ferox, Tetraclaenodon cf.
puercensis, and indeterminable pantolambdids. The latter have no
particular importance. Claenodon ?ferox occurs almost throughout
12 These probably are present in unprepared Gidley Quarry material.
50 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
the No. 3 beds but is not recorded in the No. 2 where there are smaller
and probably somewhat more primitive species of the same genus.
The Tetraclaenodon is not distinguishable from one in the Gidley
Quarry, or from fragmentary specimens from high in the No. 3. The
1,700-foot level has cf. Conoryctes sp., ?Gidleyina silberlingi, Anisonchus
sectorius, and pantolambdids. The first and last have no apparent
significance for this discussion. ?Gidleyina silberling: marks the first
(probable) appearance of that genus, which seems to be confined to
the No. 3 and more progressive than anything in the No. 2. Anison-
chus sectorius ranges throughout the No. 2 and far up into the No. 3.
The 2,250 to 2,350 levels (chiefly ‘Princeton localities’) yield
Claenodon ?feror, Gidleyina montanensis and G. spp., Anisonchus
sectorius, and pantolambdids that are undetermined but are distinct
from anything in the No. 2 beds. Loc. 15, which 1s somewhere in the
lower No. 3 although not determined exactly as to level, yields an
ally of Paromomys not demonstrably distinct from the No. 2 repre-
sentation of that group.
These lower No. 3 beds as a whole appear to be characterized by
the survival of some genera, including Claenodon, Tetraclaenodon,
Anisonchus, and perhaps Paromomys and Conoryctes, and of at least
one species, Anisonchus sectorius, from the No. 2 beds, and by the
appearance of a distinctive advanced species, Claenodon ?ferox, and
a similarly distinctive and relatively specialized genus, Gidleyina.
These two latter may not be real cases of faunal advance, for it is
possible that these animals were already present in No. 2 time despite
the lack of discovery, yet it seems tentatively acceptable to consider
them as suggestive of some slight faunal progress. The data are too
scanty for any definitive conclusion, but the indications are that these
strata have a transitional fauna between that of the No. 2 beds and
that of the Scarritt Quarry, about 1,000 feet above these lower No. 3
levels.
The Scarritt Quarry, at about 3,350 feet, provides good data and
for the first time shows decisive and incontrovertible evidence of
faunal change in the series. Ectypodus hunteri is evidently related
to some species from the Gidley Quarry but is certainly distinct and
probably of later aspect, and the same is true of Leptacodon cf. tener.
Bessoecetor thomsoni also has a Gidley Quarry ally but is probably not
a descendant of the latter. The relative degree of specialization is
not clear. Elpidophorus patratus is more specialized than its fore-
runner ?£. minor in the Silberling Quarry. Plesiadapis anceps is
very primitive in its genus yet is more advanced than Pronothodectes,
from which it could well have been derived. The relation between
Carpodaptes in the Scarritt Quarry and Elphidotarsius in the Gidley
Quarry is closely analogous to that between Plesiadapis and Pronotho-
dectes. Phenacolemur has no definitely recognizable ancestor in the
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 5t
lower beds but is a progressive and specialized form. Litolestes is
allied to Haplaletes and might have been, but probably was not,
derived from the latter (but surely not from the known species). In
any case, it is a distinctive genus abundant here and unknown in the
No. 2 beds. Tetraclaenodon occurs in both series, and the species are
not well enough known for useful comparison. Finally, Anisonchus
sectorius, which ranges throughout the No. 2, is also present here
(not in the Scarritt Quarry but at Loc. 18, which is not appreciably
different in level).
If we discount the influence of facies and chance as far as possible,
it then seems clear that there is definite faunal advance from the
Gidley and Silberling Quarry levels to that of the Searritt Quarry,
that this advance is in some cases of generic rank (Pronothodectes—
Plesiadapis and Elphidotarsius—Carpodaptes) but in others only
specific (probably in the genera Ectypodus, Leptacodon, Bessoecetor,
Elpidophorus, and Tetraclaenodon) and in part of even less degree
(Anisonchus sectorius).¥
The progressive difference in the two faunas compared is real, but
it is not very marked, much less than would be expected from a
difference in level of some 2,000 feet. As nearly as such an imperfect
parallel can be drawn, the difference seems to be definitely less than
that between the Torrejon and the Tiffany and probably not much
greater than between the Tiffany and Clark Fork.
The highest faunal level, 4,350 feet, has provided little good evidence
bearing on this discussion. Plesiadapis rex may be more progressive
than P. anceps but is not definitely shown to be so. The Paromomys-
like form is too poorly known for useful comparison. Tetraclaenodon
still occurs at the higher level and so probably does Gidleyina, their
degree of advance, if any, over comparable forms lower in the No. 3
beds not being clear.
Claenodon ?ferox still occurs here and seems to be quite as in the
lower No. 3, although the material is scanty. Thryptacodon, identi-
fied with much probability but not certainty, 1s progressive over
Prothryptacodon of the No. 2, but the intermediate stages in the lower
No. 3 are unknown. An ally of Haplaletes here is too poorly known
to give reliable evidence. Hlpidophorus, probably patratus, carries
through from the Scarritt Quarry level. The data are too inadequate
to say that there is no advance over the Scarritt Quarry, or indeed
over the lower No. 3, but they suggest that the difference will probably
prove to be slight if it exists at all.
13 The tremendous vertical range of Anisonchus sectorius in this field, nearly 3,000 feet, is extraordinary,
This species and to still greater degree this genus are of unusually wide geographic range in the Paleocene,
the species known from New Mexico to Montana and the genus also in Louisiana, and also are unusually
conservative—the genus is one of the two or three that pass through from Puerco to Torrejon in New Mexico.
52 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
CORRELATION OF MAMMALIAN FAUNAS
Data are not at hand for any exact correlation of the No. 1 beds.
Of their mammals ?Ptilodus sinclairi, identified here with some prob-
ability, is a No. 2 species. Claenodon is typically a Middle Paleocene
genus, ranging in this field into the Upper Paleocene. Chriacus is a
very long-lived genus, Lower Paleocene to Lower Eocene, and is here
rather dubious but apparently of more progressive aspect than its
Lower Paleocene allies. A/imotricentes is otherwise known only in the
Middle Paleocene of this field, and M. angustidens (which, however,
is known only from the highest No. 1 beds) ranges to the top of the
No.2. Tetraclaenodon is typically Middle Paleocene, perhaps ranging
into earliest Upper Paleocene in this field, and the species may be the
same asin the No.2. As identified by Russell (personal communica-
tion), invertebrates from immediately below the No. 1 beds, or perhaps
in their base, are definitely of Paleocene aspect, and most of his com-
parisons are closely with Middle to Upper Paleocene forms. On the
whole the scanty evidence favors reference of the No. 1 beds to the
Middle Paleocene, and none of it definitely suggests or warrants
reference to the Lower Paleocene. The physical stratigraphic evi-
dence, while even less decisive, is also consistent with belief that the
No. 1 beds are not markedly different from the No. 2inage. Nothing
suggests or justifies correlation with the Puerco.
As already shown, the fauna of the No. 2 beds is a unit as far as
correlation is concerned. From his first discovery (Locs. 5 and 6),
Douglass (1902) already recognized equivalence to the Torrejon.
Matthew (1914) accepted this fauna as of the same age as that of
the Torrejon.* Gidley (1909, p. 616, footnote, apparently not else-
where explicitly stated, but his definitive opinion) considered it ‘about
equivalent to ... or perhaps somewhat older than the Torrejon.”’
The detailed evidence of the mammalian fauna is as follows:
Ptilodus: A Middle Paleocene genus, P. montanus very near P. mediaevus of the
Torrejon.
Ectypodus cae Upper Paleocene genera, but species here quite distinc-
Parectypodus|"| tive and generic assignments not certain.
Eucosmodon: Forms indistinguishable generically on the basis of similar material
range through the Paleocene.
Gelastops: Probably allied to, but distinct from, Didelphodus of the Lower Eocene.
Probably allied to but less specialized than Acmeodon of the Torrejon.
Prodiacodon: Middle Paleocene genus, identification here not certain and species
highly distinctive.
Leptacodon: Genus otherwise Upper Paleocene, species distinctive.
Myrmecoboides: Unknown elsewhere, no value in close correlation.
Stilpnodon: This genus and its family too imperfectly known for close comparisons.
Bessoecetor: Otherwise known only in the No. 8 beds in this field, allied to the
typically Lower Eocene Palaeosinopa, but more primitive.
14 His correlation chart, fig. 2, seems to correlate it with the Puerco, but his text shows that this was not
intended.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 53
Aphronorus: Allied to Pentacodon of the Torrejon but apparently more primitive.
Eudaemonema: Allied to Mixodectes in the Torrejon and (perhaps more distantly)
to other genera in Upper Paleocene and Lower Eocene, more primitive than
any of these allies in some respects, but not on the same line of descent as
any of them.
Elpidophorus: An Upper Paleocene genus but here with a distinctive primitive
species, which may well prove generically separable.
Picrodus: Probably allied to Zanycteris of the Upper Paleocene, relative degree
of specialization not determinable.
Pronothodectes: Allied to Plesiadapis of the Upper Paleocene but distinctly more
primitive.
Elphidotarsius: Allied to Carpodaptes and Carpolestes of the Upper Paleocene but
distinctly more primitive than either.
eer amnus tence primitive genera, but exact lines of descent not clear
Palaechthon : : :
enough for more precise use in correlation.
Palenochtha
Conoryctes: Genus otherwise Middle Paleocene as far as definitely known, species
imperfectly represented but indistinguishable from C. comma of the Torrejon.
Psittacotherium: Genus otherwise certainly known only in Middle Paleocene,
species indistinguishable from P. multifragum of the Torrejon.
Claenodon: Genus otherwise chiefly Middle Paleocene but extending into Upper
Paleocene in this field, species more primitive than that commonest in
Torrejon, more comparable to but perhaps slightly more primitive than the
second Torrejon species.
Deuterogonodon: A distinctive genus not known elsewhere, perhaps especially
allied to, but if so distinctly more advanced than, Protogonodon of the Puerco.
Prothryptacodon: Allied to Thryptacodon, Upper Paleocene and Lower Eocene,
but more primitive.
eee ests , se unknown elsewhere, of Paleocene aspect but not more
Spanoxyodon|'| closely useful in correlation.
Mimotricentes: Perhaps especially allied to Tricentes, Middle Paleocene, and if so
slightly more primitive, but probably on a different line of descent.
Didymictis: Genus Middle Paleocene to Lower Eocene, relationship of two species
not clear enough for more exact correlation, but a third indistinguishable
from D. haydenianus of the Torrejon.
Ictidopappus: Unknown elsewhere, perhaps especially allied to Viverravus of the
Eocene, but if so more primitive.
Dissacus: Genus Middle Paleocene to Lower Eocene, species not identifiable.
Ellipsodon: Genus otherwise only positively identified in Middle Eocene, species
close to #. acolytus, Torrejon, perhaps slightly more advanced or on different
line of descent.
Litaletes Genera unknown elsewhere, general aspeet Paleocene, perhaps
Litomylus rather more Middle Paleocene, but not exactly determinable as
Haplaletes to evolutionary position.
Tetraclaenodon: Genus typically Middle Paleocene, probably reaching Upper
Paleocene in this field, two species close to those from Torrejon, one of them
indistinguishable.
Coriphagus: Genus otherwise only in Torrejon, species closely allied.
Anisonchus: Genus Lower and Middle Paleocene, also Upper Paleocene in this
field only, species same as in Torrejon, but probably also reaches Upper
Paleocene here.
Pantolambda: Genus certainly identified only in Middle Paleocene, species allied
to those of Torrejon.
54 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
In résumé, there are 13 genera all of Paleocene aspect but con-
fined to this fauna and of little use in exact correlation. Of the eight
other genera confined to this fauna, four have their closest allies
in the Torrejon and four have their closest known allies in the Upper
Paleocene, but three of these here appear to be distinctly more primi-
tive than their Upper Paleocene relatives. Eight genera are other-
wise typical of the Torrejon, and these here include two species
indistinguishable from those of the Torrejon. The other species of
these genera are in most cases closely allied to those of the Torrejon,
mostly without definite evidence of being more or less advanced,
but one may be less and one may be more specialized than the most
comparable Torrejon species. Four genera are common to this fauna
and to that of the Torrejon, but they also appear in later beds. Their
species are here generally closer to the Torrejon species and in two
cases appear to be identical. Two genera probably range nearly
or quite throughout the Paleocene, one of them here represented
by a typically Torrejon species, but one that does range into some-
what later beds. Five of the genera are otherwise known only in
Upper Paleocene (in some cases also ranging into later) beds, but in
each case the species here present is decidedly distinctive, and in no
case is a Middle Paleocene ancestor or close ally otherwise known.
This evidence conclusively proves the fauna to belong to the
Middle Paleocene and to be close to the Torrejon in age. It does
not preclude a slight difference in age from the Torrejon, but dif-
ferences of facies and geographic position are adequate to explain the
faunal distinction without supposing the age to be different, and if
the age is slightly different they obscure the evidence for this. There
is nothing suggestive of the Puerco. There is a greater resemblance
to the Upper Paleocene than is shown by the Torrejon fauna, but the
evidence suggests that this is largely or wholly due to the discovery
in this place and facies of forerunners of later groups not themselves
really later here than the Torrejon.
The only other very closely correlatable horizon is that of the
Scarritt Quarry. The correlation has been discussed elsewhere
(Simpson, 1936b), where it was shown that the quarry fauna itself
is very close to that of the Tiffany in age but may be slightly earlier.
From a more general point of view, there is some suggestive but
inconclusive evidence strengthening the probability of slightly earlier
age for this than for the principal Tiffany horizon. The probable
occurrence of Tetraclaenodon at an even higher level, replaced in
the Tiffany and all later beds by the more advanced and possibly
descendant genus Phenacodus, weights the evidence in this direction,
as does also the occurrence at about this level of a specimen indis-
tinguishable from Anisonchus sectorius, a Torrejon species. The
occurrence of Claenodon indistinguishable from the Torrejon C. ferox
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. i)
far up into the No. 3, even higher than the Scarritt Quarry, is less
dependable but suggests the same conclusion. It is also suggestive
that the age difference between the Gidley and Silberling Quarry
faunas, which are very close to the Torrejon in age, and that of the
Scarritt Quarry appears to be less pronounced than the age difference
between the Torrejon and the Tiffany.
The Scarritt Quarry and equivalent levels may be correlated with
the Tiffany, with the reservation that it is possibly a little earlier,
and may be placed in the earliest Upper Paleocene. ‘The highest
faunal level, that of Locs. 11 and 13, is likewise surely Upper Paleo-
cene, probably about Tiffany.
The lower levels in the No. 3 cannot be well correlated on present
data. They are bounded by Torrejon and (probably early) Tiffany
equivalents. There is some slight evidence that they are in fact
transitional between these two and represent most of the gap in
time known to exist between Torrejon and Tiffany, rather than being
more definitely associated with one or the other. If there is a dis-
tinct faunal break in this series, it would be logical to look for it at
the most obvious change in sedimentation, at the base of the No.
3. The scanty fossil evidence does not warrant such a positive
conclusion. The only known elements in the basal No. 3 that look
toward the later faunules are Claenodon ?ferox of little or no value,
since this is, in fact, a typical Torrejon species, and Gidleyina, which
is more suggestive but in itself far from conclusive.
Posonspe NEW Wyomine: MOonrmTANA:
Sanenariaasin Bighorn Basin Crazy Mountain Field
(No mammals : (No mammals
known) Clark Fork known)
RT Re Ree ie “Tiffany-Bear
Tiffan 5 Creek”
y (Princeton Quarry)! |-------- PAIGE SORES
PALEOCENE (Faunal break) (Faunal break) Je aay pie
Bere eS: ee a
: : Gidley
“ oe 5 J
Torrejon Torrejon Quarry Lebo
(Faunal break) (aunalibreak) |22=s2 22" iy aires
Tt: yy ea
Puerco Puerco (Age uncertain)
CRETACEOUS (Unconformity) Lance ‘Hell Greek
1 Dr. Jepsen has not yet applied valid stratigraphic names to these levels, distinguished by him.
119212—37. 5
56 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
The known faunas of this field thus seem to cover most of or all
the Middle Paleocene and to continue, probably without a marked
break, into the early Upper Paleocene. There are here at least
2,000 feet of sediments of about the same type above the highest
level with identified mammals, and sediments of somewhat different
character in contiguous areas might raise this figure to as much as
4,000 feet. These beds doubtless represent most of or all the con-
siderable span of later Upper Paleocene time not represented by
faunas here, and they may well run into the true Eocene.
The tentative arrangement based on these correlations is summed
up in the diagram on page 55.
Such a chart is necessarily excessively simplified, so that it does not
adequately represent abundant and exact evidence where this is
available; at the same time it must be explicit, so that in places it does
not reveal the extent of uncertainty and lack of evidence. It is a
correlation of strata by their known faunas, never entirely coextensive
with the strata themselves. The “faunal breaks’’ listed definitely
imply intervals of time not represented by known faunas, but it does
not follow that strata of these ages are necessarily lacking in the region
in question. The same is true of the parts outside the known distri-
bution of faunas that are labeled ‘no mammals known.”
ECOLOGY
NOTES ON THE NONMAMMALIAN BIOTA
Despite the abundance of nonmammalian fossils in the field and
the existence of good collections made by Silberling and others, this
part of the biota has not been adequately studied for this area. It
is beyond the scope of the present work to include any critical exami-
nation of the material or to attempt complete floral and faunal lists,
nor has it seemed necessary to delay publication until such special
studies could be made. In the present section a few previous records
are mentioned, and beyond this the only purpose is to suggest the
broad outlines or general character of the biotic background of the
mammalian faunas.
Plants—A number of small collections of leaves have been made in
this field, but as far as I know no attempt to collect and to classify
its whole flora has been made. Knowlton (1902) has published a
special note on one small collection, and several other species are listed
incidentally in the literature.
Knowlton (1909, p. 194) listed a few plants from the ‘lower mem-
ber of the Fort Union” (by which he usually means the Hell Creek or
Lance), 1,000 feet below the top. Asitis not clear what he considered
“the top”’, this is not explicit. He states that they were ‘‘about 1,200
feet below the small mammals now being studied by Mr. Gidley’’,
which probably means the Silberling Quarry and would (by my esti-
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 5G
mate) place the plants near the top of the Bear. They are said to be
from sec. 29, T. 6 N., R. 16 E., a section that is mainly on the Bear
but includes a small area of No. 1. The identifications are:
Salix sp. Aralia notata.
Populus amblyrhyncha. Leguminosites arachioides.
Populus cuneata. Vitis xantholithensis.
Populus genetrix. Credneria daturaefolia.
Populus daphnogenoides. Phyllites cupanoides.
Populus sp. Carpites sp.
These are all common Fort Union species. Knowlton has also re-
ported them all as Lance (e. g., Knowlton, 1919), but on examining the
evidence it is found that Vitis (or Ampelopsis) xantholithensis, Cred-
neria daturaefolia, and Phyllites (or Pterospermites) cupanoides are
true Fort Union species reported in the Lance only on the strength
of this occurrence, and that there is also some question as to whether
Aralia notata really occurs in the Cretaceous, whereas it is abundantly
characteristic of the Fort Union.’® In short, this is a Fort Union
flora, which would be expected since it is probably from the Bear,
which may well be Paleocene or even properly Fort Union, or possibly
from the Lebo, which everyone now agrees to be Fort Union.
Other small collections more definitely from the Bear and older
than any of the known mammals of this field are mentioned above.
A collection surely from the Lebo, ‘‘close under the massive gray
sandstone of the Fort Union” (i. e., the base of the No. 3 beds), in
“Sec. 15, T.6 N., R. 15 E.” (actually sec. 22, as later surveys have
shown; sec. 15 includes only the very base of the Lebo), was made by
Campbell, Stanton, Stone, and Calvert, and identified by Knowlton as
follows (in Stone and Calvert, 1910, p. 755):
Plaianus haydenit. Sapindus grandifoliolus.
Populus cuneata. Grewia obovata.
Populus amblyrhyncha. Grewtopsis platantfolia.
These are all Fort Union species, and all occur in the Glendive
region. The majority also occur in the Lance but are certainly in
the Fort Union in this section.
Knowlton (1902) described a small flora collected by W. H. Weed
from ‘‘the sandstone series above the bend of the Sweet Grass, west
of Porcupine Butte, Montana.’ This locality is in this field, at the
extreme western edge of the mapped area, at a high horizon, far above
any identified mammals. The following species were recorded: Glyp-
tostrobus europaeus,s Onoclea sensibilis fossilis, Aralia ?notata, and
Tilia weedii. The last has not been recorded elsewhere, but the
others are Fort Union (and questionably earlier) species, and Knowl-
15 This incident casts further doubt on the supposed community of the Lance and Fort Union floras, for
there are many other areas where beds probably or surely Paleocene and definitely post-Hell Creek have
been arbitrarily called ‘‘Lance.’’
16 G. e. ungeri in the original list, but later emended by Knowlton to the form here given.
58 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
ton concludes that the beds are Fort Union. Incidentally this is
some slight evidence that these upper beds are still in the Paleocene,
but this perhaps cannot be taken very seriously.
It seems probable that the Fort Union flora of this field is closely
similar to that of the Bull Mountain field (lists in Woolsey, Richards,
and Lupton, 1917) and also to the very large and well-known flora
of the Glendive area (lists and references in Knowlton, 1919), in short,
that it is the typical, wide-ranging Fort Union flora, which seems to
have shown little geographic or stratigraphic differentiation from
Upper Cretaceous to Upper Paleocene and throughout the West.
Leaves are found at almost all levels and throughout the field, although
really well-preserved specimens can seldom be recovered. Specimens
apparently of the handsome species Platanus nobilis were particularly
noticeable in the sandstones stripped from above the bone layer
in the Gidley Quarry. The general occurrence of leaves here and
elsewhere in the field suggests that the whole region was heavily
forested, chiefly by deciduous trees, during much of or all the Paleo-
cene. It demonstrates the presence of a well-developed arboreal
habitat and of abundant food for browsing and frugivorous animals
and suggests (but by no means proves) that the more open type of
plains habitat was here relatively restricted or absent.
Knowlton (1927, pp. 184-186) has summed up the Fort Union
flora in general, and probably his remarks apply in large measure to
the plants of this field throughout Lebo and Melville time. About a
dozen species of small ferns and the sensitive fern Onoclea are known,
as well as horsetails, ‘a beautiful little selaginella”’, and abundant
grasses and sedges. Only one palm, and that rare, is recorded. ‘It
was, however, a very large-leaved fan-palm, showing that conditions
were not altogether unfavorable.” Conifers are abundant, with
three sequoias, a yew, bald cypress, two or three pines, and an arbor-
vitae that was particularly abundant. There is a rare ginkgo. The
most conspicuous and abundant dicotyledonous trees were poplars,
with leaves suggestive of the quaking aspen. Sycamores also were
abundant, some with very large leaves. Viburnums were also very
common and were ‘‘presumably small trees or shrubs, known at the
present day as arrowwood, blackhaw, tree cranberry, etc.”’ There
were also oak, alder, chestnut, hazelnut, maple, elm, magnolia, hick-
ory, walnut, birch, beech, ampelopsis, bittersweet, and rare figs and
laurels.
Invertebrates—Mollusks occur throughout the field and often in
extraordinary abundance. The majority of them are fresh-water
mussels and gastropods, although a few may be terrestrial snails.
The common types are several different species each of ‘Unio’,
Viviparus, and Campeloma. A large collection from just below the
Lebo has been listed page 17. Dr. Russell has also identified the
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 59
following from Loc. 24 Gmmediately above the mammals): Viviparus
retusus, V. planolatere, and Lioplax nebrascensis; and the following
from Loc. 67, high in the No. 3: ?Nedionidus senectus, ?N. s. declivis
(type locality; Russell, 1934), Vieiparus retusus, and V. cf. planolatere.
(There are also large collections not adequately studied, nor is it
necessary to discuss them here where only the general ecological
aspect is in question.)
Altogether, the invertebrates show that fresh water was abundantly
present and thickly populated in this area throughout the deposition
of the Fort Union.
Fishes.—Fish remains are abundant in the field but usually very
fragmentary. A few relatively good specimens have been recovered
but have not yet been prepared or closely studied. Gar scales (Lep-
isosteus sp.) are common at most surface localities and also occur in
all three quarries. A still commoner fish in the quarries, seldom
found on surface exposures, probably because of its more fragile
character, appears to be an ally of, or to belong to, Stylomyleodon
Russell, and Russell has already recorded its presence in this field
(1928, p. 107). Specimens recently collected will add greatly to
knowledge of thisform. Despite the almost complete lack of associa-
tion of mammal remains in the Gidley Quarry, it is the rule rather
than the exception to find fishes, apparently mostly Stylomyleodon,
represented by associated strings of vertebrae, despite the loose
articulation of these, and not infrequently also with parts of the skull
in association.
Reptiles—Champsosaur and crocodilian remains, generally too
imperfect for close identification, are common at all levels. Isolated
teeth suggest that Allognathosuchus was the common crocodilian.
Champsosaurs occur up to at least 3,000 feet, and possibly more,
above the base of the No. 3. Turtle remains are also common, but
they also are usually too fragmentary for ready identification. Hay
(1908, p. 498) has, however, described Aspideretes nassau from a
specimen found by one of the Princeton parties in the No. 3 beds.
Gilmore (1928b) has mentioned three fragmentary specimens of
Peltosaurus sp. from the Fort Union No. 2 Silberling Quarry and has
also named Harpagosaurus excedens, the type of which is from the
same locality. Lizard remains are fairly common in both Silberling
and Gidley Quarries, and it is probable that these animals were
abundant in this region in the Middle Paleocene.
MAMMALIAN FACIES
The percentage composition of the principal No. 2 surface locali-
ties, all near the same level and similar in facies, and of each of the
three quarries is given in table 4 and shown graphically in figures
1 and 2.
60 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
FIGURE 1.—Diagram showing the relative abundance of identified individuals of the various orders an
families of mammals in the National Museum collection from the Gidley Quarry.
LOCALITIES GIDLEY SILBERLING SCARRITT
soar QUARRY QUARRY QUARRY
ORDER FAMILY
AG PERIPTYCHIDE_]
C.PHENACODONTIDZ
D.HYOPSODONTIDA.
E.,MESONYCHIDA
Uh
\ G.ARCTOCYONIDA
CONDYLARTHRA
H.STYLINODONTIDA
L?ANAPTOMORPHIDA
J,CARPOLESTID
K.PLESIADAPID&
L,PICRODONTIDA~
M. MIXODECTIDZE
O. LEPTICTIDA.
QIDELTATHERIDIDA.
MULTITUBERCULAT es R. PTILODONT) D4
CP.NYCTITHERIID4E IN
GIDLEY QUARRY LESS THAN
Y4 PER CENT)
FiGcuR£ 2.—Comparison of relative abundance of families of mammals at various localities in the Crazy
Mountain Field, Mont. Abundance is indicated for each locality by percentages of identified individuals
in the National Museum collection. Four Lebo surface localities (combined) and the three principal
quarries are compared.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 61
TABLE 4.—Composition (in percentages) of the principal No. 2 surface localities
and of each of the three quarries, Crazy Mountain Field, Mont.
Localities Gidley
Oo ly ’ y
rder and fami aoe 24, 25 : Quarry Quarry Quarry
MULTITUBERCULATA: 9 24 44 36
iPrilodontidaente 2-2-2 32. Se eee ae oe sh 9 24 44 36
INSECTIVORA: 1 18 12 26
aWeltatherididae =e =te sos eee ees Se 0 1 2 0
Weptictidsesases = 6 ee. Ss a eA ee ena 0 5 0 1
Ny ctitheriidaes {2s See a Sees ease one ee 0 (1) 0 0
IPANITOLEStIG BOs een at ao ees Ee ee ee 1 8 tf 15
IVIIxOGOCHIGNG 2 eso s= aaa Be ae ee 0 2 2 9
IPICTOGONUIO AOS see ae ee ee ns see ees 0 2 2 0
Wnicertaeisedis: 2Sese 2 sana Se Skt 32522 os See she 0 0 0 1
PRIMATES: 0 20 4 13
Plesiadapidae.="--25-==-22= + 22s. aes eee 0 2 0 7
@arpolestiGaevese= nes een ea oe nee eee 0 (1) 0 4
tAnaptomorphidae::2: -22-2433522252 S222 Ss See 0 18 4 0
Uncertaepsedis == so=Sa s eS ea tee 0 0 0 1
TAENIODONTA: 0 (1) 4 0
Stylinodontidae =) 22-5) = 3 SS. essen ee 0 (1) 4 0
CARNIVORA: 53 13 19 1
Anctocyonidaess=~! 32 hehe ee ceo peer obs 49 7 12 1
IVI Seid Aes! see Ss isa ee eee Se eG SSS 4 5 5) 0
Mesonychidaesc2=2-5s-22s--20L eens esses en ee esos 0 (1) 2 0
CONDYLARTHRA: 37 24 18 22
Ebyopsodontidsae £222 422-222 42-2 ee ea oe 4 20 14 21
iIPhenacodontidaes= = = ses. ee 16 1 74
Peripty chidaes. =: =- -2 =. 2. se ee ee AS 16 4 2 0
PANTODONTA: 0 1 0 2
iPantolambdidae- 2322 = - fee ee ees Se ee 0 1 0 2
1 Represented by 1 specimen (less than 0.5 percent).
The figures represent the composition of the identified collections.
They are somewhat biased in favor of the multituberculates, since
practically all the specimens of these are identified, whereas there
are numerous isolated teeth of other orders that are not identified,
but in general they are representative of the faunas as they occur.
The Gidley and Silberling Quarries agree well, within the probable
limits of chance, except for the much smaller proportion of primates
and greater of multituberculates in the Silberling Quarry, a differ-
ence probably representing slight local facial distinction.
The surface localities differ remarkably from the quarries and sug-
gest very different environmental conditions. This result is doubtless
somewhat biased by the fact that minute forms, like insectivores and
primates, are more likely to break up and are harder to find at sur-
face localities, but this does not explain the difference. Some of the
so-called surface material was, in fact, found in place. These locali-
62 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
ties have been very closely examined and fragments as small as the
smallest isolated insectivore or primate teeth recovered, so that the
almost total absence of those groups must really result from their
great rarity here. Furthermore, the arctocyonids are really much
more abundant at these localities, for not only the relative but also
the absolute number of specimens is greater for these localities than
for the Gidley and Silberling Quarries, despite the much larger col-
lections from the latter. This “surface” fauna, 90 percent carnivores
and ungulates, is of more normal type, in comparison with Tertiary
faunas generally, than are the quarry faunas. Its members average
larger than do those of the quarry faunas, and they are probably
terrestrial for the most part. This appears to be a normal flood-plain
facies, rather closely analogous to that of the Torrejon.” Its most
marked peculiarity is the higher percentage of carnivores than of
herbivores, a condition for which no probable explanation is seen.
Even at the surface localities there is a surprisingly low percentage of
animals really of large size for the Paleocene. The phenaccdonts are
of average size for that group, but the periptychids (all Anisonchus)
are moderate in size, much smaller than the contemporaneous Peripty-
chus, and most of the carnivores are also of middle size, with Deutero-
gonodon very rare and other large carnivores absent, although they
were common at this time in the Torrejon.
This rarity of large animals is still more obvious in the quarries.
Phenacodonts and pantolambdids are relatively very rare, Claenodon is
uncommon, and other large mammals do not occur. The most abun-
dant species, Ptilodus montanus, ?P. sinclairi, Leptacodon ladae, Aphro-
norus fraudator, Paromomys maturus, Palaechthon alticuspis, Meta-
chriacus punitor, Didymictis microlestes, and Ellipsodon aquilonius, are
moderate to minute in size.
In food habits the multituberculates were rodentlike, the insecti-
vores doubtless insectivorous (as the word is usually used, not signify-
ing a diet composed of insects), the primates probably mainly or ex-
clusively frugivorous, the creodonts in part omnivorous (Claenodon),
omnivorous-carnivorous (other arctocyonids), and predaceous-carniv-
orous (miacids), and the condylarths probably browsing, perhaps in
part frugivorous, or even partly insectivorous for the smallest forms.
The known fauna apparently consumed every type of food known to
have been present in the area, with the possible exception of the
mollusks.
The skeletal structure is too poorly known for any of these animals
to give much direct insight into their locomotion or general habitus.
By analogy and comparison with allied species and genera, the multi-
tuberculates and insectivores were unguiculate and probably in good
17 Correlation of faunal types and collecting methods is real but indirect. Flood-plain deposition and
facies would not normally result in concentration of fossils sufficient to permit profitable quarrying.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 63
part arboreal in habitus. The primates, also, may well have been
mainly or entirely arboreal. The creodonts were probably mainly
terrestrial, but it is probable that some of them were at least semi-
arboreal. The abundant hyopsodontids were probably, judged from
Torrejon and later allies, more unguiculate than ungulate in general
habitus, and the smaller forms may well have been arboreal. The less
common larger condylarths and the very rare pantodonts were prob-
ably terrestrial. The evidence is not at all conclusive, but it warrants
the tentative conclusion that this fauna is largely arboreal, which is well
in accord with the evidence that the quarries were in a swampy and
heavily forested area and would go far toward explaining the unusual
facies of the quarry faunas. There is, indeed, a decidedly fossorial
humerus (of unknown association with teeth) in the collection; the
facies association of arboreal and fossorial animals is not uncommon
and is in accord with a forest environment.
The ordinal composition of the Scarritt Quarry collection differs
significantly from that of the Gidley Quarry only in the almost com-
plete absence of carnivores. Within the other orders, the family com-
position is as nearly similar as would be expected in deposits of similar
facies but different ages except among the Primates. The abundant
Gidley Quarry types, Paromomys and its closer allies, are not repre-
sented in the Scarritt Quarry collection, and instead of them the more
specialized, perhaps more strictly frugivorous, plesiadapids and car-
polestids have become fairly common, although the first were un-
common and the latter very rare in the Gidley Quarry.
The Gidley Quarry is also interesting from the unusual occurrence
of its fossils and the indications of the possible conditions surrounding
death and burial of its animals. The remains are invariably frag-
mentary, and with extremely rare exceptions there is no association
of specimens. The bones seldom show any signs of weathering or
rolling but are usually fractured, and even when they abut against
wholly undisturbed matrix these fractures are clean, fresh breaks.
Some further fracturing and dissociation have resulted from the com-
pacting of the bed and development of slip planes, but for the most part
these preceded fossilization. Most of the jaws have lost some teeth
before burial, and many have lost all the teeth. These isolated teeth
(clearly lost after death but before burial) are common in the collection.
There are many bone fragments, but it is clear that the quantity of
skeletal material present, even in the most fragmentary state, cannot
by any means represent all the bones of the animals represented by
their jaws and teeth.
The rather abundant presence of fish remains, often in articulation,
and of aquatic reptile fragments and the presence of aquatic mollusks
(rare in this quarry, but present), together with the nature of the sedi-
ments, suggest that the deposit was formed in sluggish water, perhaps a
64 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
swampy stream course, ox-bow lake, or bayou. From the great va-
riety of mammals present this evidently was not the site of a single or
selective catastrophe, like many quarries that seem to represent quick-
sand or quagmire traps, but must have made a fairly complete sample
of the mammals of the surrounding forest and (to a less extent) glades.
Regardless of whether the mammals came here to drink, swam into the
water, dropped from trees, or were occasionally washed in, it seems
likely that the breaking and scattering of their bones, and perhaps
commonly their deaths also, were the result of activities of the carniv-
orous fishes and reptiles. Such a history would probably explain the
small ratio of bones to teeth (the former eaten and digested and com-
minuted, the latter less palatable and more resistant), the many clean
breaks, lack of association, and also the common intervention of macer-
ation, without apparent weathering (perhaps in part digestive, and
otherwise subaqueous) between death and burial.
THE GIDLEY QUARRY AND ECOLOGICAL INCOMPATIBILITY
Matthew (1930) has stated that ‘‘we should expect to find in a
single fossil quarry that the material of each genus represents a single
ecologic niche, or, if more than one, that they are quite distinct. We
should not, in other words, expect to find two or more closely related
species living together at the same time, within the same area, and
with the same habitat, causing their remains to be preserved together
in the same quarry . . . Hither there would be two or more species
so widely different as to belong in obviously independent ecologic
niches, or else there would be one more or less variable species.”
This is an application to paleontological data of the general principle
summed up by Cabrera (1932) as the Law of Ecologic Incompati-
bility in these words: ‘‘Las formas animales afines son ecologicamente
incompatibles, siendo su incompatibilidad tanto mayor, cuanto mas
estrecha su afinidad.”’ !§
The Gidley Quarry fauna is ideally adapted to the application, on
one hand, and to the exemplification and corroboration, on the other,
of this law and of Matthew’s remarks on the taxonomy of quarry
faunas. The species present in it were certainly contemporaneous,
and it is highly unlikely that any of the remains can have been brought
from a point so distant as to have inhabited distinctly different areas.
The general environment was probably essentially the same for all,
although unquestionably it included distinct ecologic niches. It is
possible that deposition extended over a period of years and that there
was some seasonal or other periodic change in the species of the
18 I do nct wish to claim for Cabrera a degree of originality that he disclaims for himself. Cabrera’s law
has been recognized in various forms by many authors and for a long time, but as far as I know it has never
been more exactly explained and exemplified or placed more clearly on its true ecologic (not geographic)
basis than by Cabrera.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 65
neighborhood, but this is purely hypothetical. It is most reasonable
to conclude that all these animals did live together, at the same time,
within the same area.
It is therefore to be expected that genera present in this quarry
will either have only one species each or will have species not inter-
grading at all and reflecting structurally their pertinence to different
ecologic stations in the area. With this in mind, the assumption was
made in dealing with each genus that it did include (in this quarry
fauna) just one species unless the contrary could be proved beyond
reasonable doubt.
Matthew, in the paper cited above, and most other writers on the
question of species making in paleontology have insisted on making
due allowance for variation, or using for taxonomy only nonvariable
characters, but they have adduced no real, objective criterion as to
what ‘due allowance” should be, and they sometimes seem to over-
lock the fact that there is no such thing as a truly and completely
‘nonvariable” character. Not merely as mechanical, mathematical
procedures but as a general system of logic and a grouping method
useful both explicitly and as an implicit background for dealing with
both numerical characters and attributes, the methods of statistics
provide the desired means of measuring variation accurately and the
necessary criterion as to whether this variation is or is not of the sort
normal within a species. These tests and this logical background
have been the basis for taxonomy in this study. If the specimens
pertaining to one genus could not indubitably be separated into differ-
ent groups, the conclusion has been that the fundamental hypothesis
of one species to each genus was correct. If they necessarily had to
be separated into different groups, and these groups could not be
interpreted as based on nontaxonomic differences (such as age or
sex), then and only then has the hypothesis been discarded.
Since this largely objective testing has intervened, it is not arguing
in a circle to start the study with the assumption that Cabrera’s
Law applies, and then to consider the results as a test of the validity
and an example of the operation of that law. (See figs. 3 and 4.)
The actual results are as follows: Thirty genera are represented in
the Gidley Quarry by one species each. Since this includes the greater
part of the quarry fauna, in general it is true here that the related
(congeneric) animals living at that time in this area were of the same
species. The apparent exceptions belong to six genera, each of which
is worthy of brief special consideration.
The multituberculates, with four species tentatively referred to
Ptilodus and three to Ectypodus, are the most striking apparent
exceptions. In the first place, however, the generic designations are
very dubious. It is not at all certain that the species referred to
66 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Ellipsodon
aguilonius
Litomylus
dissentaneus Litaletes
disjunctus
Haplaletes ©
disceptatrix
2.35... 275 3.15 3.55 395 4.35
LENGTH Mi, HYOPSODONTIDAE
P.maturus
205.7 M245" 2.85 S125
LENGTH M2,PAROMOMYS
FiGcurE 3.—Histograms illustrative of Cabrera’s law as applied to the Gidley Quarry fauna: a, Length
of M: in hyopsodcntids: in this and some other measurements the species nearly or quite intergrade,
and they lived in the same place at the same time, but they are morphologically very distinct and belong
to four different genera; b, length of M2 in Paromomys: the two species are morphologically similar,
probably are congeneric, and are found together, but in this dimension and in many other characters
they do not intergrade.
M. provocator
M. punitor
“at atararararata
Number of individuals
— odo BUN
Zo 48, 4649 52 55 55 61
LENGTH Moe
S$ _Quorry Specimens.
M. punitor Other Upper Lebo Specimens,
Or Peer, EEA One specimen in each sample.
40 43 46 49 5.2
WIDTH M2
Number of individuals
FicurE 4.—Histogram of measurements of second lower molars of all Lebo specimens of Metachriacus.
The distributions of these measurements, which are distributed much as are most of the characters of
the samples, are clearly bimadal, and two entities are shown to be present. These entities intergrade,
but they are separated by provenience, the two coming from different horizons and localities within the
Lebo. They are thus interpreted as closely allied but separable species. If they occurred together, a
more probable interpretation would be that they represent the two sexes of a single species.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 67
Ptilodus or to Ectypodus are really congeneric in each case. There
may well be one or more other genera represented here, although it
does seem unlikely that each species could belong to a different genus.
Aside from this possibility, the species referred to one genus are in
every case sharply distinct from each other, with no intergradation
shown. ‘This is true of many different characters, and is well shown
by table 5 of observed ranges of a few numerical characters:
TasLe 5.—Ranges of numerical characters in multituberculates, Gidley Quarry,
Crazy Mountain Field, Mont.
Genus and species LP, LM; LPy:LM;, Serre oue Cusps M,;
Ptilodus: Mm Mm
MLOMUEANALS = See Sees Renee ees 7.1-9.1 3. 2-3. 7 2. 3-2. 4 13-15 5-6:4-5
GCOUGLASSin eee eee Ne 6. 5-6. 8 3.7 1.8 13 6:4
Gidley cae. -Ba kek cei SS SDT A 5. 9-6. 1 2.5 2.4 14-15
SUUCLOU INP ee eR Naat ee oe ee ee 2. 5-3. 7 1. 7-2.0 1,3-2.0 10-13 6-7:4
Ectypodus:
OT ONGC eae eee eee 5. 2-5. 4 3. 3-3. 4 1. 5-1..6 13-14 8:6-7
NLSSCLLY See ARE hee ee ee 28 4,9-5.1 2.9 nef 13-15 10-11:6
STL OES LIG tee eee ee e e 3.3 2.3 1.4 12 9-10:5-6
Thus these species probably represent more than two genera and in
any case are so sharply distinct that each must have had its own
ecologic niche. They do not intergrade, but in some cases, notably
P. montanus, there are known species, in this case P. mediaevus,
with which they do nearly or quite intergrade but which did not live
together with them. In short, these are not exceptions to but are
striking exemplifications of Cabrera’s law.
Lepiacodon is here credited with two species. Their tooth dimen-
sions do not intergrade, although the degree of variation is well
established for one of them, and there are structural differences such
that they may well prove to be distinct subgenerically, or even
generically, when both are more completely known. This is even
more strikingly true of the two species referred to Paromomys, which
are so different that I was for a time inclined to separate them
generically (see fig. 3, 6). Didymictis also is represented by two
species perhaps not really congeneric, not intergrading at all and one
reaching a size nearly twice that of the other.
In the case of Claenodon, Gidley has been followed in listing three
species from the Gidley Quarry, all of about the same size and general
character. Differences between them do exist, but the material is
inadequate to establish the extent of variation, and when this is
established I suspect that the supposed three species will prove to be
variants of a single species. If not, this will be the unique example
of the occurrence of two or more closely related and apparently
ecologically similar species in the quarry.
68 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
EXTENT OF KNOWLEDGE OF MIDDLE AND UPPER PALEOCENE FAUNAS
Aside from details concerning only special students, the impor-
tance of such collections as those here described lies, from a more
general point of view, in the knowledge they give of the broader out-
lines of mammalian life in their time and area. To permit the proper
drawing of inferences in this broader field, it is essential to consider
the adequacy of the collections and their probable relationship to the
faunas as a whole represented by them. The adequacy of a paleon-
tological sample depends principally on three quite distinct factors:
1. The adequacy of the collection studied as a sample of the fos-
sils actually preserved in the rocks.
2. The adequacy of the preserved fossils (collected or uncollected)
as a sample of the whole fauna that actually lived in the area.
3. The adequacy of the real local fauna as a sample of the regional
fauna of the whole land mass on which it lived.
Probably the best criterion of the adequacy of a collection as a
sample of the preserved fossils is that of repetition. When collecting
begins to pile up mainly or only duplicates, it probably has achieved
sampling adequacy for the local deposit, but as long as many species
remain very rare in collections, it probably has not.
Of the 51 surely separate species known from the Gidley and
Silberling Quarries, 15 are here represented by only one specimen each,
but of these four are known by other specimens from elsewhere in the
field. Seven here have only two specimens each, but one is fairly
common elsewhere. Six are here known from three specimens each,
but two are also represented elsewhere. The other 23 species are
represented by five or more specimens each from these quarries. In
the field as a whole, of the 79 species, 19 are represented only by one
specimen. Four of these represent genera still unknown elsewhere,
and hence known from but one specimen each: Stilpnodon simplicidens,
Unuchima asaphes, Elphidotarsius florencae, and Spanoxyodon
latrunculus. Of the other 15 species here represented by only one
specimen each, three (Leptacodon cf. tener, Psittacotherium multi-
fragum, and Thryptacodon ?australis) are inseparable from species
well known in other fields, and the others all belong to genera well
known from other species, some of them abundant. For broader
studies of morphology and faunal succession, local species are not
very important, and of the 51 genera known to occur in this field,
not more than five can be considered as very poorly represented in
Middle Paleocene faunas generally.”
From these data, as well as the general make-up of the collections
and other considerations, the collections appear to represent the real
19 At least one of these, Hlphidotarsius, and possibly one or two others are closely allied to well-known
genera.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 69
fauna * of the region fairly well but far from completely. The high
proportion of species known here from only one specimen each, about
25 percent, shows that the collections, large as they are, are not yet
adequate to give a proper sample of the species that may be pre-
sumed actually to be available here as fossils. Such a high percent-
age of very rare forms indicates clearly that any further collecting
is almost certain to add to the number of known species.
As far as inference can be drawn from these data and from ecologic
and similar considerations, the situation regarding the whole pre-
served (but only partly collected) sample, that is, the forms that were
actually fossilized, is much better, but not perfectly satisfactory. It
may reasonably be assumed that there was in this general region
some variety among the larger and possibly plains-dwelling types,
such as are common in the Torrejon and also in the later Paleocene
and early Eocene in adjacent areas, but their great rarity or absence
here and the general facies present strongly suggest that the condi-
tions of deposition were such that some and perhaps many of these
were not preserved and so will never be known in this area, no matter
how large the collections made.
On the other hand, knowledge of the general composition of the
Middle and Upper Paleocene mammalian faunas of North America
as a whole may now be considered very good. It is probable that
we have representatives of almost all the orders and families and a
large majority of the genera,”! that occurred on this continent during
that time. The combined area represented by collections is now very
considerable, on the order of 1,000 square miles of actual collecting
territory, representing many times that in the ranges of sampled
faunas. The environmental variety represented is apparently great,
for the sediments yielding mammals of these ages are of many dif-
ferent sorts, many genera are represented by several well-defined
species in each, and the inferred habits of the various known mam-
mals include almost every possible terrestrial mammalian habitus.
The collecting areas certainly were part of a unified North American
land mass in the Paleocene, extend more than 1,200 miles north and
south, and were probably central on that land mass, ideally situated
for a representative sample of the whole North American fauna.
20 It would be rather hopeless to crusade against the universal and careless habit of calling a collectiona
fauna. By “real fauna’’ is meant what should properly be called simply‘“‘fauna’’; that is, the totality of
mammals that actually lived in this area, and not merely those that happen to be known or the collection,
a sample, on which this knowledge is based.
21 In accordance with the tentative views as to adequacy of local samples expressed elsewhere (Simpson,
1936a).
PART 2: CLASSIFICATION AND DESCRIPTION
OF MAMMALS
Order MULTITUBERCULATA Cope, 1884
Douglass’ first collection included no multituberculates, but in his
second collection (see Douglass, 1908) there were several teeth of this
group. <A jaw fragment with P, and M, was made type of Ptilodus
montanus, and other specimens of that species were mentioned.
Several upper teeth were referred to Chirox, not then known to be
synonymous with Ptilodus, and the probable presence of other species
of Ptilodus was mentioned. An incisor with limited enamel band
(Douglass, 1908, pl. 1, figs. 18, 20) was tentatively referred to Mizo-
dectes but may also be multituberculate (cf. Hucosmodon).
Among the first discoveries made by Mr. Silberling for the Na-
tional Museum was the now famous specimen that includes skull,
jaws, and some skeletal parts of Ptilodus. 'This was described, as a
new species, Ptilodus gracilis, by Gidley (1909) in the first of his
notes on this fauna. This is still the finest single multituberculate
specimen known. It enabled Dr. Gidley to demonstate that Chiror
is merely the upper dentition of Ptilodus (and by analogy, Bolodon
that of Plagiaulaz, in the Jurassic) and for the first time to establish
the true characters of this extraordinary group. He concluded that
Ptilodus and its kin were diprotodont marsupials. Although this
conclusion now seems untenable, it should be emphasized that such
a conclusion was logical, if not inevitable, at the time” and that
Gidley’s work on this form was very able. Gidley also noted the
presence of at least two other, smaller, species in the Fort Union
collection, although the limited material then available did not per-
mit their description, and he tentatively referred them to two Cre-
taceous species described by Marsh.
Granger and Simpson (1929), revising the Paleocene multitubercu-
lates, restudied Ptilodus montanus, Douglass’ type, concluding that
it was doubtfully distinct from Ptilodus mediaevus and P. gracilis.
The latter species was not reexamined, as Dr. Gidley was then living
and planning a definitive study of his material. It was suggested
that no valid distinction from P. montanus had been given, but the
species was accepted pending Dr. Gidley’s definitive study. Two
Torrejon specimens were doubtfully (and, as now appears, incorrectly)
referred to P. montanus.
As regards these three species, the conclusion below is that Ptilodus
gracilis is a synonym of P. montanus, which is distinct from the
Torrejon P. mediaevus, although very closely related.
22 Interesting unpublished correspondence shows, for instance, that Dr. W. D. Matthew went over
Gidley’s argument with great care at the time and agreed with his conclusion, although later new evidence
forced him to change his mind and to reach essentially the conclusion here supported.
70
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 7A
Dr. Gidley had evidently formed definite conclusions as to the
classification of the whole group in the Fort Union collection, for most
of the labels bear specific names, several of them new. Two or three
of the new species described below correspond approximately with
some of those recognized by Gidley, but as the correspondence is not
exact even in these cases and as my classification is otherwise much
unlike that suggested by Gidley’s labels, it is evident that he did not
employ the criteria here used. As he left no notes or manuscript
relating to this group, I am forced to treat it de novo (except, of
course, for his preliminary publication).
As shown by the figures given elsewhere, multituberculates made
up a large proportion of the collection and are the most important
single element in the fauna.
AFFINITIES OF THE MULTITUBERCULATA
This material has had such a decisive influence in the consideration
of the affinities of the Multituberculata that the subject must be
mentioned briefly here, although it has been thoroughly reviewed
elsewhere (Simpson, 1929c, 1929e; Simpson and Elftman, 1928;
Granger and Simpson, 1929).
The earliest ideas (Falconer; Owen; Marsh; Cope, 1884; Osborn,
1888), influenced by the descriptive analogy of the shearing teeth to
those of some diprotodont marsupials (and a few other inconclusive
characters), were that the multituberculates were marsupials. When
the teeth of Ornithorhynchus were discovered, Cope saw in them
some resemblance to the multituberculates and suggested that the
latter were monotremes.”
When the fine specimen of Ptilodus here redescribed was discovered,
it gave Dr. Gidley the first real opportunity to study the problem on
a broader basis than that afforded by the often misleading dental
characters. After a careful, but only provisional, analysis, he con-
cluded that Ptilodus and the other multituberculates are diprotodont
marsupials, diverging from those of Australia in the Jurassic or even
in the earlier Triassic.”
Broom (1910) restudied T7ritylodon and critically examined Gidley’s
publication, concluding that the multituberculates were an indepen-
dent group without near affinities with the living monotremes, mar-
supials, or placentals. Later (1914) Broom studied Gidley’s original
and also a skull of Taeniolabis and then concluded that the multi-
tuberculates were monotremes.
2 A few theories unworthy of further serious consideration are passed over without any notice. All
have been listed and refuted in previous papers.
24 This and several other points in his Fort Union work demonstrate Gidley’s belief in theextreme antiquity
of modern groups of mammals and their polyphyletic evolution. This philosophical consideration underlay
much of his work and colored many of his conclusions. Specifically, he believed the Australian mammals
to have been differentiated in the Mesozoic and outside of Australia. See also Myrmecoboides, below.
119212—37. 6
72 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Matthew (first in 1915) and Granger (1915 and subsequently),
however, reviewed all the evidence of Gidley and Broom and also
some very important new evidence (chiefly hind limb of Hucosmodon)
and reached a conclusion similar to Broom’s first opinion, that the
multituberculates are not closely related to any other known mammals.
I reached this same opinion independently, and I have reviewed all
the evidence and added to it in several studies.
The new evidence from the Fort Union specimens, which I had
seen but not studied (except through Gidley’s publication) before
writing my previous papers on multituberculates, is not very exten-
sive. I confirm Broom’s opinions that the jugal is probably small in
Ptilodus and not entering the glenoid, that there is no evidence for
an alisphenoid bulla, and that there may be an uncoiled cochlea
(although I consider this unproved), as well as the point already
checked on other material that there is no true angular process. On
the other hand Broom’s evidence regarding the shoulder girdle was
certainly incorrect,” and I have elsewhere indicated that the teeth
do not support monotreme relationships. The few new details
regarding skull structure, foramina, etc., that I have been able
to make out show a rather generalized structure with no special
characters either of monotremes or marsupials. The humerus, the
only known skeletal element not fully considered in my previous analy-
sis, seems to me to be neither distinctly therian throughout, at least
in a taxonomic sense, as Gidley believed,” nor in its articular portion
nearer to the monotreme than to any higher type, as Broom believed.
Of the two, it seems to me superficially and adaptively much nearer
the Theria, but fundamentally distinct from both.
In conclusion, the present study confirms and to a slight degree
strengthens my former opinion, anticipated by Matthew and Granger
and still earlier by Broom but abandoned by the latter, that the mul-
tituberculates are a distinctive group not ancestral or closely related
to any later mammals and of extremely ancient separation from the
main mammalian stock. The very real resemblances to the Theria,
pointed out by Gidley, seem to be superficial and adaptive and to
indicate analogous stages of evolution, not blood relationship. The
likewise real resemblances to the monotremes, pointed out by Broom,
seem to be in part adaptive, in part due to the retention in two fairly
conservative but not especially related lines of a few very primitive
characters, inherited from the mammal-like reptiles.
tate conciaion might (but improbably) prove correct, but the evidence is not. The shoulder girdle is
known only from one fragment (Djadochtatherium), not conclusive but rather opposed to Broom’s view.
28 This was the basis of Cope’s belief in such relationships, and Broom added it to his table of evidence
but placed no great weight on it.
27 Gidley says ‘‘eutherian’’, which was made the subiect of a correction by Broom. In fact, Gidley was
right, historically, in his use of the term, since Eutheria was originally defined to include both marsupials
and placentals, and he was using it in that sense. It is surely less misleading at present, however, to follow
the more current usage of Metatheria for the marsupials, Eutheria for the placentals only, and Theria for
both together.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 73
METHODS OF STUDY
The identification of this large multituberculate collection and its
classification in genera and species have been peculiarly difficult, and
the work was accomplished, as far as it was possible at all, only after
prolonged and tedious analysis. Much of it led to no useful result and
so is wholly omitted here. An outline of the useful methods employed
will, however, be given, because they are similar to those used through-
out this work and are in some parts unfamiliar to many paleontologists.
In the first place, it was found that although at least three, and
probably four or five, genera are represented, 1t was not practical to
begin with a generic grouping of the specimens, as is the more usual
practice. The greater part of the collection consists of lower jaws.
With very few exceptions, which proved to be of little practical
assistance, the upper jaws all belong to a single species, and in only
one case are upper and lower jaws associated. In the family Ptilo-
dontidae the genera are usually readily distinguishable on the basis
of upper teeth, but in several cases, notably Ptilodus and Ectypodus,
they are practically indistinguishable from lower teeth alone. The
only really clear-cut generic distinctions in the lower dentition so far
recognized depend on the nature of the incisor, whether compressed
and with limited enamel band or not, and in the presence or absence
of P;.% In the present collection, only a few fragmentary specimens
(without cheek teeth) have an Hucosmodon-like incisor, and only one
P, lacks the notch for P;. These characters are therefore not available
for the bulk of the collection, and it was necessary to treat the whole
collection as if it represented only one genus, to distinguish the species
present, and then to attempt to place them in genera.
The following observations were made and recorded for each
specimen in the collection:
NUMERICAL:
Dimensions:
Length of P,.
Length and width of M;, M2, P!, P2, P’, P,°M!, and M?.
Ratios:
Length P, : Length M,.
Length M,;: Width M;.
Length M,: Length Mb.
Width M; : Width M).
Length M,: Width M:.
Counts:
Serrations of P,. L
Cusps of Mj, M2, P3, P!, M!, and_M?.
_NONNUMERICAL:
Presence or absence of P3.
Character of incisor.
Shape of P,.
28 The peculiarly reduced Ps of Microcosmodon Jepsen is also a good generic distinction, but this strange
orm does not occur in the present collection.
74 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
The dimensions and ratios are, from a statistical point of view,
continuous variates. The counts are discontinuous variates. The
nonnumerical observations are attributes and to these is to be added,
for comparison with other collections, the provenience of the speci-
mens.”°
: 2 ?Ectypodus eas
= ; 5 S/7clalrl
85 HGH! 9 Ectypodus 3 ? Ectypodus
‘62 russelli 2 silberlinge
1 1
Q
E 5 6 Z 8 9 10-8 14 rs 5 6 7 8 9 10k:
a NUMBER OF EXTERNAL CUSPS Mi
POSITIONS OF TYPE SPECIMENS
?Parectypodus yepsenn Ptilodus gracilis= montanus
Ptilodus montanus
PEctypodus silberlingi ? Ectypodus russelli
2?Ptilodus
douglassi
2.0 3.0 4.0 5.0 6.0 7-0 8.0 9.0
Ptilodus sincloiri [E§?Parectypodus [ffi ? Ptilodus gidleyi [[] Ptilodus montonus
epsent f uy
Ectypodus Ay? Ect ypod Sits ? Ectypodus grangeriE|?Ptilodus douglassi
silberlingt ; ae
b FORT UNION PTILODONTIDG. LENGTH P4.
FIGURE 5.—Histograms of typical variates of multituberculates from the Gidley and Silberling Quarries: a,
Number of external cusps on M; in four species; 6, length of Ps in the whole sample, with division of
species based on the study of this and all other available characters.
The same data were recorded for the much fewer Torrejon speci-
mens (American Museum collection) and, from publications, for the
types of other known species available for comparison.
The numerical data were then all plotted graphically in several
different ways, a few of which are here reproduced (figs. 5-7). Tenta-
tive grouping was then attempted, by taking each graphic representa-
tion and dividing it into as few groups as possible. For instance, the
length of P, histogram was at first divided into only three groups,
one from 2.45 to 3.95 mm, one from 4.85 to 5.45, and one from 5.75
to 8.75. (The single specimens at 4.3 and at 9.1 were left doubtful
and later disposed of as shown, on other data.)
It was then found that the groupings on different characters did
not include the same specimens. For instance, in the grouping on
length of P, the type of silberlingi (see below) is quite indistinguishable
29 Almost all are from the Silberling or Gidley Quarries, and the few that are not from these do not differ
significantly. Provenience was therefore not a useful datum in sorting out the collection, but only in com-
paring it with other collections.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 19
from the sinclairi group, but in the grouping on external cusps of M,
it is clearly distinct. Or, as another example, the gidleyi and douglassi
groups are not well distinguished in either of these diagrams, but are
far apart in the scatter diagram of length M, and length P, (as they
are also in others not reproduced). By continuing this process, eight
groups were eventually distinguished. A smaller number than eight
was inconsistent with the distribution of two or more characters,
and a larger number not necessary to interpret the distributions.
FIGURE 6.—Histogram and corresponding roughly fitted normal curve of length of Ps in Ptilodus montanus
from the Gidley and Silberling Quarries. The distribution is the same as that for this species included
in fig. 5, b.
A
} Lae
DOUGLASSI/< eee ry
z, 2 / ehiey)
GRANGERI..' ae aaS) iced
= ay eS /. __--MONTANUS
e @ RUSSELLKe' —e-, Mec
a? JEPSENIN {2
4 oy
xz SILBERLINGI GIDLeYi!’
z | @
pe N Ee ‘
, ye ‘Al’
fo) IO el
| So - /
SO Se
°2.0 3-0 4.9 5.0 5.0 7-0 8.0 9.0
LENGTH P4
FIGurRE 7.—Scatter diagram of length of Mi; and length of Ps for all Gidley and Silberling Quarry specimens
of multituberculates that show both of these measurements, with separation into species based on this
and all other characters.
The two most abundant groups (sinclairi and montanus in the classi-
fication as finally worked out) were then tested for homogeneity, by
statistical methods which showed that their deviations from normal
form in any case are not of probable significance, and then for numer-
ous continuous variates of each of these groups the mean, standard
deviation, coefficient of variation, and the standard errors *° of each
40 I have given standard errors throughout. The probable error, which has nothing to recommend it, is
0.6745 times this figure.
76 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
of these were calculated. These new figures furnished a check on the
probable taxonomic significance of the grouping. A priori, the range
of variation allowed by the graphic grouping appeared too large for
single species. Most paleontologists would think it wholly unjustified,
for instance, to place a lower premolar measuring 7.0 mm in length in
the same species with one measuring 9.1. But the coefficient of
variation of the whole group to which these belong is only 5.3, and that
is small, rather than large, for a linear dimension of teeth of a single
mammalian species, so that there is no reason to believe that the graphs
have permitted confusion of two species.
These statistical data, furthermore, when considered from a taxo-
nomic biological viewpoint, suggested the degree of variation to be
expected in species of this family and also gave a criterion for judging
the greater or less usefulness of certain characters for taxonomic dis-
tinction. Thus, in turn, a check was possible on the groups too small
for the useful calculation of these derived data.
After full consideration of all these primary and secondary data,
it was clear that of the eight groups finally achieved and checked each
represents a variable morphological unit, that the variation in each is
not greater than commonly occurs in natural species, but that no two
can be combined without producing a unit statistically heterogeneous
and morphologically much more variable than a species. The biologi-
cal conclusion is thus that eight species are present.
Eight species of a single family seems a relatively large number to
occur at a single horizon and locality,®! but there is really nothing
extraordinary in thisnumber. The ptilodontids are analogous to small
rodents, and there is, for instance, hardly any region of the United
States today that does not have more than eight species of Cricetidae.
This large number of species clearly is not due to making the specific
distinctions too small. On the contrary, since we have definite, con-
crete statistical data warranting this, allowance has been made for
much more variation than is usually granted within a paleontological
species. The largest individual of sinclairi, for instance, is 48 percent
larger than the smallest (length of P,), a much greater variation than
the current rule-of-thumb methods permit, although the demon-
strable probability that they do belong to one species is very great.
A few specimens could not be placed in any of these eight species.
A Eucosmodon-like lower incisor, for instance, probably does not belong
with any of them. (It is also from a different locality.) Several
upper teeth, not of montanus, cannot be associated with lower jaws,
and while they almost certainly belong among the species based on
31 All these species occur in the Gidley Quarry. While the specimens from the Gidley Quarry cannot all
be exactly contemporaneous, they are practically so. Nevertheless the probability that they represent a
succession of years or seasons helps to explain the faunal variety, not by the evolution of new species but by
the opportunity for more thorough sampling of a large area.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 77
lower teeth they must be left incertae sedis with respect to them. It
was, however, possible to place ali the lower jaws with P,, My, or both
in one of these species.
It was next necessary to compare these eight species with those
previously named and described. Ptilodus mediaevus and_troves-
sartianus, the only named approximately contemporary species,
demanded closest comparison. The probably later species Ectypodus
musculus, I. cochranensis, Parectypodus simpsoni, and P. tardus were
also compared. No others are sufficiently close to warrant detailed
comparison.
At this point the attribute of provenience becomes of essential
importance. As an example, the number of serrations on P, of the
montanus group from the Fort Union, counted on 29 individuals,
varies from 13 to 15, the mean being 13.8 and the median 14. In the
six available individuals of comparable size (mediaevus group) from
the Torrejon, five have 12 and one has 18 serrations, mean 12.2,
median 12. If all these be considered as one sample the distribution
is:
12 serrations—5. 14 serrations—19.
13 serrations—9. 15 serrations—2.
The distribution shows no bimodality, and it might be assumed that
the sample is homogeneous with respect to this character, but this is
fallacious, as the sample is not, in fact, drawn from one population.
Table 6 shows the distribution of 35 individuals with serration count
of P, and provenience considered as attributes.
TABLE 6.—Contingency table of serration counts and provenience for 35 specimens of
P, of the Ptilodus mediaevus—montanus group
\_Serrations
SP 12 13 14 15
Locality See
Momtanads=ss222= 0 8 19 2
New Mexico____- 5 1 0 0
Although the data are inadequate for the calculation of coefficients,
it is clear that there is positive association of Montana and 14 serra-
tions and of New Mexico and 12 serrations, and this association is of
significantly greater degree than would be expected from effects of
random sampling. In spite of the fact that the two samples overlap
in this respect and that they could not be separated if they were from
one population, it is clearly very probable that the two populations
78 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
from which they were, in fact, drawn do differ in the mean number
of serrations.
Similar differences associated with provenience occur in several
other characters and show that Ptilodus mediaevus and P. montanus
are distinct. They could not be certainly separated if they occurred
together, although even in that case the significantly greater varia-
tion of the combined samples would lead one to suspect that the
population was heterogeneous.
If we accept the specific groupings finally adopted as valid, some
interesting conclusions regarding variability and the value and signifi-
cance of various characters for taxonomy in these animals are possible.
The length of P,, the most useful single dimension as this is far the
commonest tooth in multituberculate collections, has a coefficient of
variation of 9.3+1.6 in the sinclairi group. This is high, but com-
parably high coefficients have been recorded for linear dimensions of
teeth of mammalian species.*? In the montanus group this coefficient
is 5.3+0.6. This dimension is thus much less variable in the avail-
able sample of the latter species and to that extent seems a more
reliable taxonomic character for it than for the smaller sinclairv.*?
On the other hand, the length of M, in the sample of sinelairi is very
constant, coefficient of variation only 4.4+1.1, and in montanus some-
what more variable, coefficient 5.7 +£1.35.
Thus appear the interesting facts that in sinclair? Py, is highly
variable and M, little variable in length, while in montanus both are
moderately, and about equally, variable. As a result of these facts,
the ratio length P, : length M, is very much more variable in sinclaira
(standard deviation 0.22 +0.06) than in montanus (0.04+0.01). This
is also accentuated by the further fact that in montanus, but not in
sinclairi, these two dimensions are positively correlated, that is, that
in montanus the larger premolars tend to be associated with the larger
molars, while in sinclairi the available data show no such tendency.
Another expansion of this same unexpected and important fact, clearly
visible on the scatter diagram (fig. 7), is that in sinclairi the line of
regression of length M, on length P, is horizontal or even slightly
inclined downward to the right, coefficient nearly zero or a very small
32 E. g., in Pal. Sin., ser. C, vol. 5, fase. 5, Helga Pearson gives coefficients up to 11.4 for M3 of one side
in one sex of a single homogeneous human race and Coefficients up to 8.1 for probably very homogeneous
groups of fossil suids.
33 How misleading the best judgment may be when not aided by statistical treatment is shown by the
fact that although Gidley clearly relied on size of P4 chiefly for specific separation (as shown by the nature
of his groupings and also by his unpublished specific names, all of which denote size), he placed the small
sinclairi specimens in one species but divided the large montanus into three species, although the variability
of the former is nearly twice that of the latter. The misleading factor is that the absolute difference in the
extremes is less for the small than for the large species. Although this is the striking character to the eye,
it is not the essential factor either from a statistical or from a biological point of view.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 79
negative fraction, while in montanus it is inclined upward to the right,
coefficient a significant, positive, fraction.“ It is quite possible
although unprovable from these data that the distinctly different
type of variation in these two species characterizes different generic
groups.
The ratio length M, to width M, has a standard deviation of 0.17-
0.04 in sinclair: and 0.13+0.03 in montanus. The means of the two,
2.2 and 2.0, respectively, do not differ enough to prove that they are
a reliable method of distinguishing these species. The character may
however, be taken as of taxonomic value in such cases as that of
silberlingt where this value, 2.6 in the unique specimen, deviates
significantly from the mean for sinclairi (deviation more than twice
the standard deviation of the latter). There is a group of species
that seems to be characterized by a high value for this ratio, or
descriptively by a relatively long and narrow M,, including silberlingi,
russelli, and grangert in this fauna and Ectypodus musculus and
Parectypodus tardus in other Paleocene American faunas.
There are too few specimens with M, to provide adequate data, but
with its variability assumed to be about that of M,, its length: width
ratio would appear to be a valuable character distinguishing Ptilodus
mediacvus and montanus, in both of which the ratio averages 1.4 in
the known material, from all other species in which it is known
averaging 1.7 to 1.9.
The length of P* in the montanus group has the very high coefficient
of variation 18.5-+2.86. This is, generally, too high a coefficient for a
sample of one species, yet the other coefficients for the upper teeth
are of more reasonable size, 10.0 in the case of length M! and con-
siderably smaller for the other dimensions used. It is possible that
some extraneous P®’s have been included, but more probable that they
are all of one species and that this tooth, in any event visibly reduced
and in process of becoming vestigial, is extremely variable in length.
In either case, its length is not a reliable specific character. The
number of cusps on this tooth, varying from four to seven in all the
specimens of this family in which it is known, seems at first sight to
be a helpful character and has been used in specific diagnosis, but
probably it is not. In specimens that, on all other data, rather
clearly represent one species, montanus, this cusp number shows the
full range of variation for the family, 4 to 7. The data, as well as
those for P. mediaevus, are given in table 7.
34 The samples are inadequate for the useful exact calculation of the regression equations, but their general
nature is visible.
80 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
TaBLe 7.—Distribution of 23 specimens of Ptilodus montanus and P. mediaevus
on the basis of the number of cusps of P3
Te
Pe Cueps P8
ek 4 5 6 if
Locality ~_
ee aah ae ee ees hr:
Montana (montanus)__--| 13% 5 110% 1
New Mexico (mediaevus) - 2 1 0 0
1 Where it is doubtful whether a cuspule should be counted or not, I have counted the specimen as one-
half for each of the groups to which it might belong.
The median for montanus is 6 and for mediaevus 4, and this may be
a specific character, but the distributions fully overlap and the
samples do not suffice for adequate determination of the significance
of this difference. Until larger samples are at hand, this character
cannot be used with certainty to distinguish species.
Passing other characters in more rapid review, the number of cusps
of M,, particularly in the outer row, shows a range of not more than 2
in each species, even in the largest samples (which are, however,
small, not exceeding 9) and differ markedly from one species to another,
probably affording good specific or even generic characters when the
means differ by two or more. The external cusps of P* are highly
variable (range 0-3 in montanus) and the data inadequate for proper
evaluation, but probably a marked deviation in the medians has
specific significance. The inner row varies less in this material (9-10
cusps) and probably has specific value (8 in mediaevus), and the width
of this tooth is a valuable although variable character, coefficient of
variation 8.41.7 in montanus. The one available specimen of
mediaevus shows a deviation from the means of montanus nearly three
times the standard deviation of the latter, almost certainly significant.
Other teeth are known in so few cases that their characters cannot be
evaluated.
Family PTILODONTIDAE Simpson, 1927
Six valid genera of Ptilodontidae have so far been described from
the American Paleocene. Their characters are summed up in the
following artificial keys:
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT.
81
KEY TO AMERICAN GENERA OF TERTIARY PTILODONTIDAE (LOWER JAWS)
I. Lower incisor little or not compressed, relatively smaller, more
completely enameled:
A. Anterior base of P, notched:
1. P, longer than M;, numerous serrations and strong ridges:
a: Mi; relatively longer, more cuspsii_2- 5 ee ee
b. Mi relatively shorter, fewer cusps
B. Anterior base of Py not notched:
1. Pylonger than M,, numerous serrations and strong ridges__ Parectypodus
II. Lower incisor compressed laterally, relatively larger, enamel
(below tip) more or less limited to a band:
A. Base of P, notched.
1. Ps longer than M;, numerous serrations and strong ridges__ Neoliotomus
2. Pyshorter than Mj, few serrations and feeble ridges Microcosmodon
B. Base of P, not notched.
1. Py, longer than M;, numerous serrations and strong ridges. Eucosmodon
Ectypodus #6
Ptilodus *6
KEY TO AMERICAN GENERA OF TERTIARY PTILODONTIDAE (P‘)
I. P4 with two complete cusp rows and rudiments of a third___________ Ptilodus
II. P4 with only one complete cusp row, with rudiments of a second:
A. Main cusp rowrising posteriorly in an elevated point, noticeably
anterior to the posterior end of the tooth base_______________-- Ectypodus
B. Main cusp row approximately horizontal, or arched:
1. Cusps of main row heavier, fewer, rudiment of second row
SS UTONE CG Wes eet are ie Re eae 20 arn her Binge ey ey can ee Eucosmodon
2. Cusps of main row smaller, more numerous, rudiment of
SCconadesii sits eaters sree ay ee ee Ve ee Neoliotomus
fesmoiien owite sft ee ere Ne ee ay
The known distribution is shown in table 8.
TABLE 8.—Known distribution of American genera of Ptilodontidae
PALEOCENE EOCENE
Genus Lower (Puerco,
Lower Fort
Union of Clark
Fork Basin)
Pilodush = 2 eee &
Ectypodus___----
Parectypodus___-
Microcosmodon_-
Eucosmodon Oe Ser ee eee
Neoliotomus_-.__-
36 The distinction given may not be constant or really of generic value.
Middle (Torre-
jon, Crazy Moun-
tain Fort Union
No. 2, Middle
Fert Union of
Clark Fork Basin)
Upper
Lower (Sand
Coulee, Gray
Bull)
A (Tiffany, Up-
per Fort Union,
Paskapoo)
B(Clark Fork)
The lower jaws of Ptilodus and
Ectypodus show no clear generic distinction, although P4 shows them to be quite separate, although closely
related genera.
82 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Of the eight definable Fort Union species, only one, Ptilodus mon-
tanus, can be placed with certainty as to genus. This is well known,
from the entire dentition, and is so close to the genotype of Ptilodus
that it certainly belongs to that genus. The species jepseni is excluded
from all named genera but Parectypodus and Eucosmodon by the
absence of a notch for P3. It does not resemble the type species of
either of these genera very closely in the known parts (P, and M;), but
it is somewhat closer to Parectypodus simpsoni and may be placed,
very tentatively, in the same genus. Three species, silberlingi,
russelli, and grangeri, have what seem to be the most distinctive lower
jaw characters of the type of Hctypodus, large length : width ratio of
M, (2.4 to 2.6 in these species, 2.5 in HL. musculus), and large cusp
number of M, (total 14-17 in these species, 14 in #. musculus, typi-
cally 9-10 in Ptilodus). They are therefore tentatively referred to
Ectypodus, although it is not probable that all belong to one genus or
certain that any belongs to this genus. This leaves three species,
sinclairi, gidleyr, and douglasst, which are tentatively placed in Pétilodus.
The assignment is very uncertain in ail three cases, and especially so for
sinclairt, which, I suspect, may prove to represent a new genus when
upper teeth are known, but no more probable position can be given
them at present.
As previously mentioned, with this material it is now impossible to
recognize genera properly, and were it not for the requirement that a
species be referred to some genus it would be more satisfactory at pres-
ent to consider all eight species (or the seven other than montanus)
simply as species at large in the family Ptilodontidae.
TaBLE 9.—Comparison of lower dentition of 14 species of Ptilodontidae
Length|Length} LPs | LM: | S@ta | Gusps | LMi
Species P; Mi LM. | WM, pons Mi LM; Remarks
Mim Mm
?Ptilodus sinclairi_-__.___- 31 1.9 1.6 2.2 11.4 | 6.6:4 1.9
?Ectypodus silberlingi____- 3.3 2.3 1.4 2.6 12.0 | 9.5:5.5 1.9
? Parectypodus jepseni_____ 4.3 Biel 1.4 2.2 11.0 7G) eee No notch for P3.
?Hetypodus russelli_._.____ 5.0 2.9 ite 2:5 14.0 |10. 5:6.0 1.8 | Notch for P3 more
pronounced
than in &.
cochranensis.
?Ectypodus grangeri__._..- Ono 3. 4 5 2.4 13.7 | 8.0:6.7
?Ptilodus gidleyi__..-.---- 620) |, 5082/55) 10a2.4, |b2 2s - 14.3 | 6.0:
?Ptilodus douglassi___._.__ 6.6 3.7 1.8 2.2 13.0 | 6.0:4.0 1.8
Ptilodus montanus_-_------ 8.0 3. 4 223 2.0 13.8 | 5.8:4.1 1.4
Ptilodus mediaevus______-- 8.3 3.5 2.3 2.0 125.2. .5.0845.0 1.4
Ptilodus trovessartianus _ _- 5.9 Rial 1.9 1.9 13.8 6:4 1.8
Parectypodus simpsoni_-_- 4.2 2.3 2.0 21 14 tS iis | TE Salen No notch for P3.
Parectypodus tardus__-_-_- 3.0 1.9 1.6 2.4 10 8:4 1.7 | No notch for Ps.
Ectypodus musculus. -- 4.0 2.5 1.6 2.5 13 8:6 1.8
Ectypodus cochranensis__-- 4 OM eo a ad Pe eles | Sece ee 14
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 83
COMPARISON OF SPECIES
A summary comparison of the lower dentitions of the eight Fort
Union species and the other known species of Ptilodus, Parectypodus,
and Ectypodus is presented in table 9. All figures are means, regard-
less of the size or variability of the samples, which are, in most cases,
noted elsewhere. Dimensions are in millimeters. The ratios are
means of individual ratios, and not ratios of the means of the dimen-
sions involved. Fractional serrations and cusps do not exist in the
raw data, but in some cases small or doubtful serrations or cusps have
been counted as one-half.
The known distribution of all American Tertiary species is shown in
table 10.
TaBLE 10.—Known distribution of all American Tertiary species of Ptilodontidae
SAN JUAN BASIN CLARK FORK-BIGHORN Moun-
Genera and species Sand
Lower | Middle} Upper _ | Cou- Fort a
Puerco Dore: Tiffany| Fort | Fort | Fort | Clark ion | Paska:
Jo Union | Union | Union
Ptilodus: |p NE
montanus_.-------
douglasst==ss-=-=— =
de
Sinclaiys eee eee
spp. undetermined. x x x
Ectypodus: = — —_ | =--——
MUUSCULUIB = 222 x
grange. = x
russelli_.... 2. x
silberlingi__.______- x
cochranensis______-
spp. undetermined_ x
Porectypodus: — | —— | ——
simpsoni__.-.----- x
LONGUS ss eee x
jepseni___......--- x
spp. undetermined_ x x
Microcosmodon: =
aia
Eucosmodon: == ——_———
americanus a.__- -- xX
Hogs TT na SS x
molestus______----- x
COUNT ee eee x
Grofitss ss tertst Ss x
DOGS oes aa x
Neoliotomus: ———
conventus_.-------- xX!
ultimus_...--.----- x
1 Jepsen now believes (personal communication) that this is older, Paleocene.
84 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Genus PTILODUS Cope, 1881
PTILODUS MONTANUS Douglass
FIGURE 8
Ptilodus montanus Doveuass, 1908, p. 14; GipLtey, 1909, p. 615; GrancGeER and
Stmpson, 1929, p. 6382.
Ptilodus gracilis GipLEy, 1909, p. 616; GRANGER and Srupson, 1929, p. 633; non
Ptilodus gracilis (Marsh, 1889) Osborn, 1893.
Ptilodus admirabilis Hay, 1930, p. 380, to replace Ptilodus gracilis Gidley, 1909,
non Osborn, 1893.
Type.—Carnegie Museum no. 1673, left lower jaw with P, and M,.
Collected by A. C. Silberling.
Type of Ptilodus gracilis Gidley—U.S.N.M. no. 6076, skull, jaws,
and partial skeleton. Collected by A. C. Silberling.
Horizon and locality—F¥ ort Union no. 2, Middle Paleocene horizons,
Crazy Mountain Field, Mont..
Diagnosis.—Length P,, mean 8.00.07, standard deviation 0.42 +
0.05. Length M,, mean 3.4+0.07, standard deviation 0.20+0.05.
Length P*, mean 5.5+0.11, standard deviation 0.38+0.08. Width
Pt, mean 2.6+0.06, standard deviation 0.22+0.04. Ratio length
P, : length M,, mean 2.3+0.02, standard deviation 0.04+0.01. Ratio
length M,: width M,, mean 2.0+0.04, standard deviation 0.13+
0.03. Serrations P, 13-15, mode 14. Cusps P? 4-7, mode 6. Outer
cusps P* 0-8, mode 0. Inner cusps P* 9-10, mode 9. Outer cusps
M! 7-9, mode 8. Cusps M, external 5-6, mode 6, internal 4-5,
mode 4.
Discussion.—This is far the commonest single species in the fauna.
The type happens to be almost exactly at the mean or mode for every
character that it shows, and hence it is extraordinarily well fitted to
be the type, although this was, of course, accidental, as it was almost
unique when described. Gidley distinguished his Ptilodus gracilis as
being slightly smaller than P. montanus, lower jaw far more slender,
and five outer cusps on M, as against six in P. montanus. The other
characters given were, as Gidley recognized, not comparable with or
not distinctive from P. montanus. M, appears to me to have six
external cusps, rather obscured by wear.*’ The slight size distinctions
are not valid specific characters, for now that the whole collection
can be compared it is seen that P. gracilis Gidley falls definitely
within the range of P. montanus in every respect. It happens to
be one of the smallest specimens of this species, and this unfortunate
chance, not recognizable as such when he wrote his preliminary
paper, misled Gidley into thinking it representative of a separate
species.
37 The presence of only five would not necessarily be distinctive anyway, as one specimen, surely cf
montanus, has only five and two others have five large cusps and one small and indistinct.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 85
The circumstance that the two previously named species of Fort
Union ptilodonts are synonymous makes of no interest the question
whether Osborn’s incorrect reference of Cimolomys gracilis Marsh to
Ptilodus invalidates Gidley’s later Ptilodus gracilis and robs Hay’s
name Ptilodus admirabilis of any raison détre.
The distinction of this species from the very closely related Ptilodus
mediaevus of the Torrejon has already been discussed in part as exem-
plifying the methods used in this research. The more important
comparisons may be summed up as follows:
FIGURE 8,—Ptilodus montanus Douglass, U.S.N.M. no. 6076, left lower jaw (with some details completed
from right lower jaw of same individual): a, External view; 6, crown view. Three times natural, size.
Most dimensions not significantly different, but in the one specimen
of P. mediaevus that has this tooth the deviation of the width of P‘
from the mean in P. montanus is 2.7 times the standard deviation of
the latter.
Serrations of P,, mode 14 in P. montanus, and of six specimens of
P. mediaevus five have 12 and one 13.
Cusps of P?, mode 6 in P. montanus, and of three specimens of P.
mediaevus two have 4 and one 5.
External cusps of P*, mode 0 in P. montanus, and one specimen of
P. mediaevus has two. The development of this external shelf is
stronger in this specimen of mediaevus (and in another in which the
cusps cannot be surely counted) than in any specimen of montanus.
86 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
It is this character also that is reflected in the greater width of this
tooth in mediaevus. Median cusps of P* not significantly different,
but internal cusps mode 9 in montanus, and 8 in one specimen of
mediaevus.
The two species are certainly very closely related, but cannot be
considered synonymous.
No other described species could be confused with P. montanus.
Thanks to the fine specimen found by Silberling and prepared and
described by Gidley, Ptilodus montanus is the best-known multituber-
culate and typifies this order, the longest lived and among the most
widespread of all mammalian orders, despite its extinction in the
Lower Eocene. Gidley (1909) published an excellent, but explicitly
provisional and preliminary, description of the best specimen, and it
was later redescribed summarily, with new reconstructed sketches, by
Broom (1914). It has become a classic specimen and is mentioned in
practically all and figured in many of the general works on fossil
mammals (e. g., Schlosser, 1923; Osborn, 1910; Romer, 1933; etc.;
Scott, 1913, adds a life restoration, and Abel, 1912, a modified but
incorrect reconstruction based on Gidley’s figures).
The species is here briefiy redescribed, as typical of family and order
(or at least suborder). By taking into consideration numerous other
specimens of this species, and with the help of more recently described
specimens of other species, it is possible to add a few points to those
previously described and also to remove the discrepancies involved in
the previous descriptions.
Dentition—The dental formula is 35. Gidley gives 735. He
considered the second upper tooth as a canine, but it is surely an
incisor. His inclusion of a lower canine is doubtless a lapsus calami,
as there is no suggestion of such a tooth, and he does not mention it
in his description. His premolar-molar division seems to me to be
the most suitable one, although the real criterion, replacement, is not
available. The ancestors of Ptilodus probably had five upper pre-
molars, but it 1s uncertain which one was lost, and hence it is conven-
ient to call those of Ptilodus simply P!*. Its lower premolars, how-
ever, are certainly P.., of the ancestral series and are so designated.
I' is a large, high-crowned, but apparently rooted tooth with a
completely enameled crown. It is directed downward, forward, and
inward, so that the tip must have been nearly in contact with that
of its mate on the other side, although the alveoli were well spaced.
The anterior face is convex and the posterior concave vertically and
slightly convex transversely except for excavations at the sides.
There are sharp vertical external (proximal) and internal (distal)
crests, and near the tip is a more rounded posterior (lingual) crest,
so that the tip is triangular in section. There are no accessory cusps.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 87
I? is apparently present in only one specimen, the most complete
one, no. 6076, and here I suspect that it is incorrectly shown. The
tooth inserted in this position is an incomplete crown, with no root,
bedded into the broken J? alveolus in plaster. In size and structure
it is exactly a mirror image of the same part of the I of the same side,
right, which seems almost conclusive evidence that it is, in fact, the
left I’ that was loose in the matrix and was erroneously inserted in
this position. If this is true, I? is still unknown in this species.*8
I’ and I? were well spaced, and another diastema of about equal
length lies between I? and P!. The latter tooth is tricuspid in all
specimens, with three equal cusps, one anterior and a transverse pair
posterior. P? is also constant in cusp structure and resembles P! but
is wider and quadrate, with four cusps, two transverse pairs. P® is
narrower than the adjacent teeth and as shown elsewhere is extremely
variable in size and in construction. There is little doubt that it is
in process of reduction and that its great variability is a feature of
degeneration.*® The cusps are similar to those of P!~? but smaller and
more variable. There are always two transverse pairs, and on the
bulging anterior and posterior basal parts others may be developed.
When present, these are usually anterior, one or a pair, but in two
specimens there is also a cusp posterior to the constant four.
P*, the upper shearing tooth, is much enlarged and has a plane,
slightly inclined inner face. The internal cusp row consists of numer-
ous small cusps (full data on cusp number are given elsewhere), united
nearly to their apices and arranged in a straight anteroposterior line.
External to this is another row, slightly shorter posteriorly, somewhat
curved (convex externally), with fewer, larger, and more separated
cusps. On the anterior part of the external face of the tooth the base
bulges outward, forming a shelf which is usually vaguely papillate,
without distinct cusps, but may have one or more cusps.
The premolar cusps are all similar, nearly conical, sharply pointed,
the enamel furrowed and ridged radially from the point, one to three
of these ridges developed into more prominent, sharp crests.
M' has three cusp rows, and these are of nearly equal length when
unworn. The internal row, however, narrows anteriorly. All its
cusps are relatively smaller, and anteriorly they become numerous and
minute. This anterior part may be shorter than the other rows, but
it is invariably sheared off very early in life by backward movements of
P,. The middle and outer cusp rows are of equal width and cusp size
throughout, and the two are of about equal length. The cusp form is
38 The error, if such it be, is a very natural one, especially as the tooth may have lain near the alveolus
since the fragments of this specimen are very much disturbed in the matrix. Gidley notes the resemblance
of the tooth to I! except for the apparent reversal of inner and outer sides. His statement that it is smaller
is true only of the apparent height, and the tooth is broken and the true height not shown.
3* Reduction in the midst of the premolar series rather than at its ends may be characteristic of multi-
tuberculates. In the Plagiaulacidae of the Jurassic, it seems to be the third of the five premolars that is
being reduced, and hence the ptilodontid premolars may be P!~? and P4-5 of the ancestral series.
119212—37——_7
S88 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
complex. The external cusps are rounded on the external face and
have the more flattened internal face marked by a few deep radial
furrows and intervening ridges. The internal cusps are simpler but
tend to develop the same form, the furrowed side being external
(toward the middle of the tooth in both cases). The cusps of the
middle row are vaguely crescentic, the anterior face somewhat con-
cave and the posterior convex, with the two sides flattened and
furrowed.
M? is much shorter and very slightly wider than M!. Internal and
median rows are of about equal length, but the cusps of the middle row
are larger, fewer, higher, and more separate. They are more distinctly
crescentic than on M'!. The outer row is confined to the anterior half
of the tooth and generally has a single crest and outer surface, so that
separate cusps cannot be distinguished.
The sole lower incisor is a long, slender, curved, scimitarlike tooth
with a completely enameled crown, the enamel thin on the postero-
basal part and there not extending so far down. ‘The anteroexternal
face is smooth and convex, and there is a sharp anteromedial (or
buccodistal) crest, next to which the internal face is excavated. There
is a much weaker and shorter but similar posteroexternal (bucco-
proximal) crest. The long, but closed, root is inserted in a heavy
collar of bone.
I, is followed by a long diastema, and homologues of P;., of the
Plagiaulacidae are absent. P; is a tiny, 1-rooted, styliform tooth,
nearly circular in horizontal section, inserted vertically under the an-
terior edge of P, in such a way that its crown fits tightly into a notch
in the base of the latter. The crown is slightly expanded and bulbous
and is enameled on the anterior face. The tooth has no function save
that of buttressing P,.
P, is the familiar large shearing tooth, which reaches its greatest
known development in this genus. It has been so often described and
so well figured as to require no detailed description here. My, 1s a long,
narrow tooth with two cusp rows. The cusps resemble those of the
external and internal rows of M! but tend to be very vaguely crescen-
tic, concave on the posterior surfaces. M, is wider but much shorter.
The cusps are larger but less separated, in each row, and the median
valley is wider and more open. The external cusp row generally ex-
tends farther posteriorly than the internal. This tooth seems to suffer
more severe wear than does M;.
Skull.—Seen from above, the skull is almost perfectly triangular
except for the slight concavity in outline anterior to the zygoma. The
orbits are almost exactly median. The skull proper is broadest, and
about equally broad between the anterior and between the posterior
zygomatic roots, that is, between the anterior edges of the orbits and
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 89
across the cerebellar region. ‘The postorbital constriction is very
slight and postorbital processes are lacking.
The complete, sigmoid zygoma arises nearly at the middle of the
palatal region, opposite P**,
The most striking characteristic of general outline is the extremely
posterior position of the glenoid surfaces, which extend almost to the
plane of the occiput, so that the basicranial region is remarkably
short and wide. There are no pre- or post-glenoid and probably no
paroccipital processes. The wide occipital condyle has a cochleate
surface, its ventral exposure larger than the posterior.
The nasals, which are unfused, are broad, stout bones. They are
slightly constricted near their middle portion, and expanded posteri-
orly. The nasofrontal suture, slightly curved so that the frontals are
inserted into a broad and very shallow notch between the nasals,
almost exactly touches at its most posterior point a line joining the
most anterior margins of the two orbits. There are several small
foramina in the nasals, the most prominent a pair, one near the middle
of the posterior half of each nasal.
The premaxillae show no characters of interest. Their posterior
facial sutures cannot be made out, or the extent of their palatal
expansion, although they meet at the midline as far back as the anterior
end of I’.
The maxilla is a relatively very large bone. It has a small frontal
contact above the anterior rim of the orbit.“ It forms the whole
anterior root of the zygoma and apparently at least half of the zygoma
itself. I can detect no jugal. It may have existed as a slender bone
above the zygomatic portion of the maxilla, as shown in Broom’s
restoration, but this is purely hypothetical. No. 9710 has the zygoma
nearly complete, although fractured and dislocated, and in it no jugal
is visible, so that it is quite possible that this bone was wholly lacking
or fused with the maxilla. On the palate, the maxillae form a strong
transverse bridge, principally between P'~? of opposite sides. Anterior
to this in the midline they form a pointed process between the anterior
palatal foramina, which are very large and lie between but in greater
part posterior to the second incisors. Posterior to the transverse
palatal bridge of the maxillae is a slender median bar between the
vacuities, but whether this is formed by the maxillae, palatines, or
both cannot be made out. Broom (1914, p. 123) has mentioned that
“the front part of the maxilla is curiously excavated as if it retained a
large nasal floor cartilage.’? The excavation opens at the postero-
lateral side of the anterior palatal foramen and is cut off from the
nasal passage proper by a flange of bone from the maxilla. As shown
40 Broom (1914) shows maxilla and frontal separated by a small lacrimal, but this is hypothetical (dotted
lines on his drawing). In fact, no lacrimal is distinguishable, and there does appear to bea definitely visible
frontomaxillary contact on the right side. This region is known in several multituberculates, and none
shows a lacrimal, at least outside the orbit. Probably this bone is lacking cr intraorbital in this order.
00 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
in another specimen (no. 9762) it runs backward into the maxilla for a
short distance and ends in a blind point. An alternative, and I
think slightly more probable, explanation is that this peculiar pocket
lodged a nasal diverticulum. The large paired palatal vacuities,
regularly long and elliptical in outline, extend from opposite the
posterior end of P? to the anterior end of M!'.!
As shown vaguely in the best skull and definitely in no. 9710, the
maxillopalatine suture parallels the dental border and ends anteriorly
at the rim of the vacuity opposite the anterior end of M'. The
palatines thus form the whole of the quadrangular palatal bridge
principally between the first molars. In no. 9762 this is seen to be
pierced on each side by a long, large, horizontal canal opening anteri-
orly at the vacuity and posteriorly in the basicranial region, perhaps
in the choanae. The posterior palatal rim is slightly thickened.
The choanae are completely separated by a thin, vertical, median
plate of bone, probably the vomer, as suggested by Broom. The
palatopterygoid crests are low and rounded and do not extend down-
ward to the level of the palate. There apparently was no hamular
process.
The frontals are fairly large and cover most of the interorbital
region and form the superior border of the orbits. There are thin
lateral forward extensions of the parietals, which lap over the frontals,
as correctly shown by Broom, but they do not reach the nasals or
maxillae as in Taeniolabis.
The anterior branches of the sagittal crest nearly follow the parieto-
frontal sutures, and the crest becomes single only near the junction
with occiput and is there low. The parietals are fused on the midline,
in distinction from the nasals and frontals. The presence of an inter-
parietal, as shown in broken lines by Broom, is purely hypothetical.
The parietosquamosal suture is not determinable. The large un-
broken piece of bone on the left side does not show it, and this suggests
that the posterior end of the suture was more lateral, and the parietal
here broader, than shown in Broom’s restoration.
The squamosal forms the posterior portion of the zygoma. Anterior
to the glenoid surface its lower face is slightly excavated, and this
may have been for the jugal, as suggested by Gidley and tentatively
shown on Broom’s restoration, but this is by no means certain and
seems to me improbable. The glenoid surface, in any event, 1s wholly
on the squamosal and is oval and nearly plane. From it the squamosal
swings almost straight medially to the lambdoid crest.
The basicranial region is very obscure, but a few details can be
made out. The anteroventral part of the occipital condyle is a very
thin flange underhanging a pocket in the posterior part of which is
41 They are considerably too short in Broom’ srestoration, the anterior margin being placed too posteriorly.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 91
the condylar foramen, apparently single as Broom says, although a
second opening may possibly have occurred along an adjacent broken
area.
Farther anteromedial is another foramen, opening into a canal run-
ning forward, probably for the carotid. Between these and the
temporal fossa is an elliptical opening on the skull as preserved elon-
gate anterointernal-posteroexternally. There is some bone exposed
at the posteroexternal end of this, not far from the posterointernal end
of the glenoid surface. This doubtless belongs to the auditory appara-
tus, but I cannot identify the elements. How this opening may have
been floored is not determinable, but I agree with Broom and differ
from Gidley in finding no evidence that there was an alisphenoid bulla.
Part of the bony internal wall of the vacuity is broken, revealing that
it contains a relatively large, gently curved, cavity, interpreted by
Broom as an uncoiled cochlea, a possible but not certain interpretation.
The anteroexternal rim of the vacuity is formed by a ridge continuous
anterointernally with the pterygopalatine crest, and posteroexternally
with the squamosal stalk attaching the glenoid (and zygoma). In
the lower surface of this ridge near its junction with the pterygopalatine
crest is a distinct foramen. Immediately above this, more in the
lateral cranial wall, is apparently another foramen, directed forward
and downward. The first of these openings does not, as Gidley
believed, lead to an alisphenoid canal, and the two foramina together
probably represent the foramen ovale. Above and somewhat posterior
to the end of the palate, in the lateral cranial wall, is a large anterior
lacerate foramen. Separate rotund or optic foramina cannot be dis-
tinguished, and they are probably confluent with this fissure. More
anterior, at the same or a slightly higher level, above the anterior end
of M!, is a smaller foramen, probably the ethmoid or sphenopalatine
foramen.
Mandible.—The rodentlike form of the mandible is well shown in
the figures. The symphysis is unfused.* The coronoid process is
feeble, somewhat recurved, and possibly pointed—it is not quite com-
plete in any specimen. The masseteric fossa is deep and bounded by
a strong flaring flange below. The pterygoid fossa is still more pro-
nounced and the pterygoid crest still more flaring. There is no angular
process. The dental foramen is at the bottom of the deep pterygoid
fossa, and the very small mental foramen is beneath the diastema.
Vertebrae.—There are several vertebrae, but they are so poorly pre-
served that little can be made out beyond the suggestion, already
noted by Gidley, that neck and tail were both long and heavy.
4 He said (1909, p. 619), ‘‘there appears to be an alisphenoid canal’’, and I assume that he was referring
to this opening.
43 Apparently it never fused in any multituberculate.
92 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Humerus.—The head is large, oval, anteroposterior diameter slightly
greater than transverse diameter. The trochanters are not preserved.
The shaft is slender, deltoid crest present but weak. The entepicon-
dyle, slightly broken, is large, and the foramen present but small. The
external side of the distal end is broken, and the ectepicondylar region
is not preserved. What remains of the radial articulation suggests
that it was nearly spherical. The trochlea is not a broad groove
bounded by a sharp crest as in later mammals (except monotremes,
in which, however, these articulations are still less Ptilodus-like than
are those of primitive Theria) but forms another subspherical, slightly
crested, condyle. The fossa for the olecranon is sharp and deep.
Ulna.—The proximal end of the ulna has a nearly round, concave
articular surface. The shaft is stout, with a strong biceps insertion.
The distal end, which lacks the epiphysis, is widely expanded.
Pelvis —Broom (1914) interpreted what Gidley took for the pelvis
as a shoulder girdle and restored it in such a way as closely to resem-
ble the monotreme shoulder girdle, but Granger added a note to
Broom’s paper (at Broom’s request) pointing out that Gidley’s opinion
was correct. This was based on the fine Hucosmodon material later
described by Granger and Simpson (1929) and by Simpson and Elit-
man (1928). There can be no doubt that the element is a pelvis,
although it is so extraordinary that Broom’s error was quite under-
standable.“* The detailed descriptions of the HEucosmodon pelvis
already published make it unnecessary to go into any detail regarding
that of Ptilodus. As far as one can judge from the imperfect material,
the two are closely similar throughout, except that in Péilodus the
pelvis is slenderer, with weaker muscle origins.
Femur.—The femur of Ptilodus is also much like that of Hucosmodon,
except for being smaller and relatively weaker. The great trochanter
does not rise so far above the head, and the lesser trochanter is rela-
tively a little smaller, with less expanded head.
Tibia and fibula.—These bones are poorly preserved and show little
except their relative sizes and the remarkably deep posteroproximal
excavation of the shaft, as in Hucosmodon.
Measurements of the two types included here and the most important
statistical data follow. Here, and elsewhere, I do not give all the
many measurements on which these figures depend. The data are
given in a form that shows all the essential and few or no nonessential
figures and that makes comparison much easier and more reliable than
the publication of long tables of raw data.
44In Gidley’s figure (1909, fig. 4) the pelvis is restored by analogy with marsupials. The Hucosmodon
specimen shows this restoration to be incorrect.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 93
TaBLE 11.— Measurements of Ptilodus montanus: Continuous variates
|
Variate N R M og V
liens Jee es 36 71-91 8.04 +0. 07 0.42 +0. 05 5. 3+0. 6
Lb) ee ae 9 3. 2 -3. 7 3.44 +0. 07 0.20 +0. 05 5.741. 4
Rai ey ore sey 21 2.6 -3. 4 2.97 +0. 12 0.55 +0. 08 18.5+4+2.8
ee 21 2.0 —2. 6 2.29 +0. 03 0. 150+0. 023 6.6+1.0
| DE Ns ee ae 12 4.8 -6.0 5.50 +0. 11 0.388 +0. 08 6.9+1.4
Weakeseee (282 = 12 2.1 -2.9 2.62 +0. 06 0.22 +0. 04 8.441.7
| 262, UE Sa a 9 4,2 -6.0 5.03 +0. 17 0.50 +0. 12 10. 0+2. 4
Ua ht ae 6 2. 25-2. 40 | 2.33040. 018 | 0. 045+0. 013
1 cr 9 1.8 -2. 2 1.98 +0. 04 0.13 +0. 03
TaBLe 12.—Distributions of discontinuous variates: Ptilodus montanus
ae eee Hn ees tend 8 Ba lets Lge Lage Ss 1
Demranonsieg yA ose A 19 , gpl Oe ea eee 2 4
hres Hareeabie in 9 Median cusps P?: eat CEein fa 9
9
External cusps M;: [O- aoa = = on = Be are 2
Nokes at SS i re | bah? Naa 7
Internal cusps P?:
Internal cusps M;: ec ac ‘ BOs 2adiink HEA :
ae eee ee ee ee 1 | ae Re re ee oe 1
iPxtermal cusps). Mas 45.5.6) 0-2 57) gexternal cusps! M':48. 2. 3.27. 2 646
Internnalycusps: Mos ig. 24-2252 ok 4 O scerestir beeen erste 144
ee A en lee eae 3% Ces Sees ae %
py pa ol ea eee RNS irae k soe be 5 Median: cusps Mis 9e22. 1 22 os 51
= 3»
Cusps P®: ima i lise: Bi oe 58 1041 Tite eae ee 2
ad wee eae, oe wy ee 9 oe Be 1+ a Mediancusps#V2 = 320s 2 ee ees 4
0 eB Ei tat ie ey, AF 5 rn) BOR Per oe 2
Internal cusps M?: a
External cusps P!: Se 2 ee ae ee aes oe
‘ : | NPR Ae 2a 1%
5 ee ee Canes 5 Me
1Jn all the teeth with five cusps and in all but one with six, the cusps additional to four are evidently
anterior, but in one with six there is an extra anterior and an extra posterior cusp. The tooth with seven
cusps has two extra anterior cusps and one extra posterior.
3 That is, a slight bulging shelf, generally vaguely papillate, but without distinct cusps.
The internal cusps of M! are invariably sheared by P, at the anterior
end and cannot be accurately counted in any specimen. Failure to
recognize this would lead one to believe the various stages of wear
typical of different species, if not genera. The outer cusps of M? are
also too obscure to count in the available specimens.
This species is abundant both in the Gidley and Silberling Quarries,
where its remains are among the commonest and are the best preserved
of all the fossil mammals. No significant difference can be observed
between the specimens from the two quarries, and the preceding data
are based on the combined sample from both. Two specimens surely
of this species were found at Loc. 50, and a broken P, from Loc. 51
probably belongs to it.
BULLETIN 169, UNITED STATES NATIONAL MUSEUM
94
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FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 95
?7PTILODUS DOUGLASSI Simpson
FIGURE 9, a
?Ptilodus douglassi Stupson, 1935d, p. 225.
Type.—U.S.N.M. no. 9795, right lower jaw with Ps-M>. Collected
by A. C. Silberling.
Horizon and locality —Gidley Quarry (and two referred specimens
from Silberling Quarry), Fort Union, Middle Paleocene horizon,
Crazy Mountain Field, Mont.
Diagnosis.—Mean length P, (three specimens) 6.6, deviation from
mean of P. montanus —1.4, 3.3 times standard deviation of the latter.
Length M, (type) not significantly deviating from that of P. montanus.
Ratio length P,:length M, (type) 1.8, deviation from mean P. mon-
tanus —0.5, 12.5 times standard deviation of the latter. Length
M,:length M, (type) 1.8, deviation from mean P. montanus+-0.4
(standard deviation not calculable, but difference almost certainly
significant). Serration and cusp number not significantly different
from P. montanus.
Remarks.—Expressed in other and less definite words, the species
is structurally closely similar to P. montanus but differs significantly
in its smaller size, relatively much smaller P,, and relatively smaller
M, (or, much larger M, relative to Py and M,). P, also appears to be
somewhat lower in lateral contour, but this cannot be adequately
checked.
No species other than P. montanus resembles this closely enough
to demand further comparison.
TasLe 14.— Measurements of individual specimens of Ptilodus douglassi
a a LP M, | LM; | 8
5 4 | LM Mi | *!Ta | Cusps | Cusps
U.S.N.M. no. LP, LM, | WM, | LM Hons M, M:
L W L W
Mm | Mm} Mm| Mm | Mm
Viti see ee 6.5 3.7 UBT 2.0 2.1 1.76 Die 1.8 13 6:4 4:2
ORSS Reese ee eee GGh eee ae ere aA ee ee |e ee Ee cone lees aeee 713
OS88p mee ee eee 658) | Ses | Eo See ee SSS ee ee |e a eee eee oe 13
2PTILODUS GIDLEYI Simpson
FicureE 9, 5
?Ptilodus gidleyt Simpson, 1935d, p. 225.
Type.—U.S.N.M. no. 9763, left lower jaw with P, and broken Mj.
Collected by A. C. Silberling.
Horizon and locality —Gidley Quarry, Fort Union, Middle Paleocene
horizon, Crazy Mountain Field, Mont.
Diagnosis —Length Py, type, 6.1 (two other specimens 5.9 and 6.1).
Length My, type, about 2.5. Ratio length P,:length M, about 2.4,
96 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
that is, not significantly different from P. montanus or mediaevus but
much higher than in any other known species of this or closely related
genera. Serrations P,, type, 14 (two other specimens 14 and 15).
P, very short and high in lateral contour, rising well above the grinding
plane of M;.
Remarks.—Except for its somewhat more elevated Py, this closely
resembles P. montanus in its known proportions and other morpho-
logical features, but it is much smaller (deviation of length P, from
mean of P. montanus —2.0, nearly five times standard deviation of the
latter), too much so to consider it a small variant of montanus, despite
the considerable variability of the latter.
a b
FIGURE 9.—Ptilodus, comparative outline drawings of lower dentition: a, P. douglassi Simpson, U.S.N.M.
no. 9795; b, P. gidleyi Simpson, U.S.N.M. no. 9763; ¢, P. sinclairi Simpson, U.S.N.M. no. 9770. Crown
and external views, all drawn as if left lower jaws (a and ¢ reversed from right lower jaw). Three times
natural size.
P, of this species is of the same size as in P. trovessartianus. Ma-
terial is insufficient for full analysis, but if we assume the variability
of both not to be much greater than in P. montanus, the shorter M,
of ?P. gidleyi * and the resulting larger ratio length P,: length M,
are surely significant. These same differences distinguish it even
more sharply from the somewhat larger species ?P. douglassi. No
others resemble it closely.
TaBLE 15.— Measurements of individual specimens of ?Ptilodus gidleyi
LP :
U.S.N.M. no. EP; LM, cM Sores Cusps M,
Mim Mm |
Gap aite see ea See: BM REPRE FP IE 550 || eee | ew oe 15
1g 3 a pe el eS E.Sun 6.1 ea. 2.6 ca. 2.4 14 76:?
it (1 aed tara enn OR PON. Bia | any arn ee oe SPE I 14
46 This is not exactly determinable from the specimen, but the error of measurement can hardly exceed
0.2 mm and is almost surely less. Alveoli in a referred specimen also indicate a very short Mi.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 97
An isolated P, from Loc. 50 (American Museum collection) measures
6.1 mm in length, has 15 serrations, and closely resembles the type of
this species in form. There can be little question that it belongs here,
as it is so close to the known mean for this species and far outside the
range of any other species recognized in this field.
?PTILODUS SINCLAIRI Simpson
FIGURE 9, c
?Ptilodus sinclairi Simpson, 1935d, p. 225.
Type.—U.S.N.M. no. 9770, left lower jaw with P,-M>2. Collected
by A. C. Silberling.
Horizon and locality—Gidley Quarry (referred specimens from
Silberling Quarry), Fort Union, Middle Paleocene horizon, Crazy
Mountain Field, Mont.
Diagnosis—Length P,, mean 3.1+40.07, standard deviation
0.29+0.05. Length M,, mean 1.9+0.03 standard deviation 0.08.
Ratio length P,: length M,, mean 1.6+0.08 standard deviation 0.22 +
0.06. Ratio length M,: width M,, mean 2.2+0.06, standard devia-
tion 0.17+0.04. Serrations P, 10-138, mode 12. Cusps M, 6-7:4,
mode 7:4.
Remarks.—Some of the peculiarities of this species, second only to
P. montanus in abundance, have already been discussed above. Its
very small size at once distinguishes it from any species of related
genera except ?Ectypodus silberlingi (diagnosed below), and Parecty-
podus tardus, with which it cannot be congeneric, as it has P3.
The two specimens (6089 and 6090, and also a third, 6149, so labeled
but not published by number) that Gidley at first (1909, p. 623) re-
ferred to “Ptilodus formosus?”’ (Marsh) (=Halodon formosus Marsh)
belong to ?Ptilodus sinclairi.® Adequate comparison with the frag-
mentary Cretaceous types of Marsh is impossible, but in view of the
very different age and of the fact that when close comparison is pos-
sible not only the species but also the genera are very distinct, it may,
I think, be assumed that the Fort Union forms do not belong to
Cretaceous species.
As noted above, it is improbable that this species belongs to Ptilodus,
but it cannot at present be clearly distinguished from that genus.
45 Gidley did not change their labels, but it is practically certain that he recognized their pertinence to a
distinctive species. He recognized ? Ptilodus sinciaizi (under a different, unpublished name), and so labeled
about half the specimens that I piace here, covering almost the same range of variation, so that in this case
his specific criteria and mine lead to nearly the same result. He also included, however, one or two speci-
mens that I place in other species.
98 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
The principal numerical data on this form are as follows:
TaBLE 16.—Measurements of ?Ptilodus sinelairi: Continuous variates
Variate N R M o Vv
| 2 i ee ae 15 2. 5-38. 7 3. 130507 |-0. 29 +0. 05 Oro =e 116
1 ign Se 8 1. 7-2. 0 1. 88+0. 03 | 0. 083+0. 021 a Sea ig (ee |
LPs My! 8 1. 32-1. 95 1.61+0. 08 | 0.22 +0. 06
LM,: WM,_-_- 8 1. 9-2. 4 2.25+0. 06 | 0.17 +0. 04
Tasie 17.—Distributions of discontinuous variates: ?Ptilodus sinclairi
fi Internal ‘cusps: Mis = 2Ss58e2 Ais Wea,
P 1 eo eEixternall cuspse Motes 2s 25 ae An ela3
Serr is Py: a
SO 1225. valintermalecusps Moss. a ae =e 22 ES
[een
(G22 223
ct ‘usps M | ee ae ea h
External cusps M abe’
i Mi Ms Serra-
U.S.N.M. Dp LP, LM: LM; : Cusps | Cusps
no. ue DM, | WialeGMy | oe) Mie lees
ral! We ic A ee sine menal Petes
Mm} Mm| Mm)| Mm| Mm
OO TEESE Soe 2.6 1.9 0.8 0.9 0.9 L387 2.4 Ppa 10 7:4 4:2
LAYS ae ee ane es 229i 9 0.8 i 0.9 1253 2.4 Mei 12 ? ?
DFO oe ea ee Boa) Dad 0.9 0.9 0.8 1. 94 1.9 1.9 11 6:4 4:2
O77 OLS sese aoe eee ee Me 3 Heir 1.9 0.8 0.9 0.9 1.95 2.4 Pal 12 6:4 4:2
These four best specimens include practically all the extremes in
these characters.
A P, collected by A. C. Silberling on January 21, 1903, now in the
Princeton University collection, measures 3.0 mm in length and has
12 clear serrations and 1 obscure. It is indistinguishable in any way
from some of the smaller variants of Ptilodus sinclairi from the Gidley
Quarry and is referred to that species. Nothing like it has been dis-
covered at a Lower Paleocene horizon, nor is it exactly matched in
any of the many Lance specimens (Cimolomys, sensu lato) known to
me. It bears the horizon designation ‘‘Puerco”’ (by which was then
meant approximately the series later called Fort Union No. 1), the
number 14, and the locality ‘“Moen and Beck”’ (a very general locality
including a large area along Bear Butte). Mr. Silberling informs me
positively that this is from Loc. 65, and this can be taken as correct.
The specimen is thus the oldest mammal ever found in this field.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 99
Genus ECTYPODUS Matthew and Granger, 1921
?7ECTYPODUS GRANGERI Simpson
Figure 10, a
?Ectypodus grangert StmPson, 1935d, p. 226.
Type.—U.S.N.M. no. 9801, left lower jaw with P,-M,. Collected
by A. C. Silberling.
Horizon and locality —Gidley Quarry, Fort Union, Middle Paleocene
horizon, Crazy Mountain Field, Mont.
Diagnosis—Length Py, type and mean of four specimens, 5.3.
Length M,, type and mean of three specimens, 3.4. Ratio length P,:
length M,, type 1.56, referred specimen 1.53. Length M,: width M,,
type 2.6, mean of three specimens, 2.4. Serrations P,, type 14, other
specimens, two 14, one 13. Cusps My, type, 8:7, other specimens one
8:7, one 8:6. Apex of P, nearly on a level with grinding surface of
Mi.
Remarks.—Like the other two new species tentatively referred to
?Hctypodus, below, this differs from all species referred to Ptilodus in
the large length: width ratio and large cusp number of M,, characters
that appear to be surely significant and make closer comparison with
species of Ptilodus unnecessary. ‘This, and the next two species, are
excluded from Parectypodus by the presence of P3.
The present form compares very closely with Hctypodus musculus in
all its visible characters. In spite of the small size of the samples, the
considerably greater size of ?E. grangeri is almost certainly significant,
and its association with wide geographic separation and with a dis-
tinct difference in age shows the species to be distinct.
The principal measurements are given in table 19.
TasLe 19.—Measurements of individual specimens of ?Ectypodus grangeri
U.S.N.M. xe LPs LM, | Sera | Gusps
aay LP, LM wM tions M,
16 Ww 1 1 Py
Mm Mm Mm
O80 0 eee ot oi Lo weet nS 5:2 3.4 1.6 1.53 2.1 14 8:6
OS OTE Renee Eh. 5 Sik ees 5.3 3.4 1.3 1. 56 14 8:7
OU a SAS eee 3 ee edo 5 see SC. 5 ee | ears eee aed (ep ene wee ee 13
OS 2a eee ee a anes ae 4 ease 2S eee 2 Bee ee bees oe 14
tf SS Se es ee ee ee (ope te 3.3 DBs Ye eee ae 255i) 2k Ae 8:7
|
?ECTYPODUS RUSSELLI Simpson
Ficure 10, b
?Ectypodus russellt Simpson 1935d, p. 226.
Type.—U.S.N.M. no. 9765, left lower jaw with PM. Collected
by A. C. Silberling.
100 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Horizon and locality.—Gidley Quarry, Fort Union, Middle Paleo-
cene horizon, Crazy Mountain Field, Mont.
Diagnosis —Length P,, type and mean of three, 5.0. Length M,,
type and referred specimen, 2.9. Ratio length P,y:length M,, type
and referred specimen, 1.7. Length M,:width M,, type 2.4, referred
specimen 2.6. Serrations P,, type 14, others one 15, one 13. Cusps M,,
type 10:6, referred 11:6. Cusps Mg, type and referred specimen 5:2.
Crest of P, elevated well above M,.
MITT)
Ca / Dereewy
IG
p
d
FIGURE 10.—Ectypodus and Parectypodus, comparative outline drawings of lower dentitions: a, H. grangeri
Simpson, U.S.N.M. no. 9801; 6, EH. russelli Simpson, U.S.N.M. no. 9765; c, EH. silberlingi Simpson,
U.S.N.M. no. 9798; d, P. jepseni Simpson, U.S.N.M. no. 9769. Crown and external views, left lower
jaws. Three times natural size.
Remarks.—This species considerably resembles the preceding one,
and I was at first inclined to consider its smaller size as due only to
variatiow, as it is well within the possible size limits. That would,
however, make the range in M, external cusp number for the com-
bined species twice as great as has been demonstrated for any known
species of this or allied genera, even in much larger samples, and the
probability is very greatly against this occurring in a single species
and against the association of larger cusp number with smaller size
being due to accidents of sampling. It is possible also, although
less clear, that association with a slightly larger length P,:length M;
ratio is significant. The added character of a more elevated P,
makes the specific distinction practically certain.
P, of this species very closely resembles that of Ectypodus coch-
ranensis. However: (a) It here has a definitely larger notch for
P;, (b) the localities are well separated, (c) the ages are distinctly
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 101
different, (d) only P, can be compared, and (e) extremely slight differ-
ences in this tooth are commonly associated with specific or even
generic differences in other parts of the dentition.”
In size this species is a little closer to H. musculus than is E. grangeri,
although still definitely larger, but its other distinctions from £.
grangert are distinctive in about the same degree from EF. musculus.
A tooth of this species (no. 6088) was referred by Gidley to ‘‘Ptilodus
serratus’? (=Halodon serratus Marsh) in his preliminary publication
(1909, p. 622) but with the reservation that it might later be placed
in a new species. Had he completed his work, Dr. Gidley would
unquestionably have placed this specimen in a new species, as is done
here. The remarks made above, regarding specimens of ?Ptilodus
sinclairi referred tentatively to ‘‘Ptilodus formosus’’ are equally
apropos here.
TaBLE 20.— Measurements of individual specimens of ?Ectypodus russelli
Mi M;
Serra-
pena sect [ee ei ay |g Bl 2 LM LM : Cusps | Cusps
U.S.N.M. no. LP, en tions
Te peel eee epyrt) HM 9) TOW east tops, M1 M:
Mm | Mm | Mm | Mm | Mm |
Uses 4.9 2.9 1 1.6 1.5 1.6 1.8 13 11:6 5:2
O(G0)ssee sees een 5.0 2.9 1.2 | 1.5 1.4 1.72 2 1.9 14 10:6 5:2
BOSS eee el ese 5 fll eee | Wee eles eee [ovoescoe fecseseee) eee 15
|
?ECTYPODUS SILBERLINGI Simpson
Figure 10, c¢
?Ectypodus silberlingt Simpson, 1935d, p. 226.
Type.—U.S.N.M. no. 9798, left lower jaw with incisor and Py-Mg;.
Collected by A. C. Silberling.
Horizon and locality Gidley Quarry, Fort Union, Middle Paleocene
horizon, Crazy Mountain Field, Mont.
Diagnosis.—(Only one specimen.) Length Py, 3.3. Length M,,
2.3. Ratio length P,:length M,, 1.4. Length M,:width M,, 2.6.
Serrations P,, 12. Cusps M,, 9-10:5-6.% Crest of P, relatively low.
Remarks.—In most of its characters, this species falls well within
the range of ?Ptilodus sinclairi, with which it would be confused in
casual examination, but its deviation from the mean of sinclairi in
length of M, is 5 times the standard deviation of the latter, and in
the ratio length M,:width M,, 2.3 times, and the marked difference
in cusp number of M, is also surely significant. The species cannot
be, and the genera probably are not, the same.
47 Russell (1929, p. 173) in describing EF. cochranensis was doubtless referring to my ?E. russell! when he
wrote, ‘‘Undescribed premolars of about the same size as EH. cochranensis occur in the Fort Union beds of
Montana, but these teeth differ markedly from the present specimen in having a prouounced undercutting
in the anterior margin of the crown.”
48 That is, clearly at least 9:5, and in each row rudiments of another cusp so that it is doubtful whether
the count should be 9:5 or 10:6.
102. BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Among other species, it most closely resembles Ectypodus musculus,
but aside from the different horizon and locality it differs in being
somewhat, perhaps significantly, smaller and in having more cusps
on M,, as well as other minor distinctions that may prove also to be
significant when a larger sample permits their evaluation.
Measurements of the type other than those given above: Width
M,, 0.9; length M>;, 1.2; width Ms, 1.0; ratio length M,:length Mb,
1.9; cusps Ma, 25:3.
?ECTYPODUS species
U.S.N.M. no. 9772 includes three unassociated last upper premolars,
one broken, from the Gidley Quarry. They have one complete row
of 11 cuspules, or serrations, and a rudimentary anteroexternal basal
row of 2 cusps, both strong and distinct, the more posterior larger
and opposite the third or fourth cusp of the main row. These teeth
suggest Hetypodus musculus, but the elevation of the posterior end of
the main crest is less than in that species, and the apex is not on the
most posterior cuspule but on the fourth or fifth from the posterior
end. Neoliotomus conventus is inadequately known, but apparently
these specimens are less symmetrical in lateral contour. Size and
cusp number surely distinguish the species from any comparable form,
and the generic reference is doubtful. The lengths of the two more
complete teeth are 4.8 and 4.5 mm.
These probably represent the upper dentition of one of the species
bere named from lower jaws, and by inference somewhat more prob-
ably one referred to ?Hctypodus, but the association cannot be estab-
lished. From the ratio length Py,:length P* in Eetypodus musculus
(1.48), the lower P, should be 6.7—7.1 mm in length, about as in
?Ptilodus douglassi, but the latter has no characters suggesting
Ectypodus. ?2Ectypodus grangeri may be based on the corresponding
lower teeth, but it seems somewhat too small.
Genus PARECTYPODUS Jepsen, 1930
?PARECTYPODUS JEPSENI Simpson
FicureE 10, d
? Parectypodus jepsent SIMPSON, 1935d, p. 227.
Type.—U.S.N.M. no. 9769, left lower jaw with P,-M,. Collected
by A. C. Silberling.
Horizon and locality —Gidley Quarry, Fort Union No. 2, Crazy
Mountain Field, Mont.
Diagnosis.—(Only one specimen.) Length Py, 4.3. Length M,,
3.1. Ratio length Py:length M, 1.4. Length M,:width M,, 2.2.
Serrations Py, 11. Cusps M,, 7:6. P,long andlow. No notch for P3.
Remarks.—This can be compared only with the later Parectypodus
simpsoni. Its longer M,, lower length P,:length M, ratio, smaller
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 103
serration number, markedly different cusp formula of M,, and other
lesser differences show it to be markedly distinct. It differs even
more, but in somewhat different ways, from Parectypodus tardus.
The generic reference is very dubious.
Measurements of the type other than those given above: Width
M,, 1.4.
Genus EUCOSMODON Matthew and Granger, 1921
EUCOSMODON SPARSUS,‘! new species
Figure 11
Type —U.S.N.M. no. 10113, part of lower incisor, with a small
adherent jaw fragment. Collected by A. C. Silberling.
Horizon and locality —Loc. 25, and referred specimens from Loc.
51 and the Silberling Quarry, Fort Union, Middle Paleocene horizon,
Crazy Mountain Field, Mont.
Diagnosis.—Type incisor, maximum transverse diameter 4.0, mini-
mum 1.4 mm, ratio 2.86.
FIGURE 11.—Eucosmodon sparsus, new species, U.S.N.M. no. 10113: Part of lower incisor and fragment of
jaw. External view and cross section at anterior end of incisor as preserved, with enamel band shown in
heavier outline. Four times natural size.
Remarks.—This is an interesting form worthy of formal record
despite the imperfection of the material. Poor as this is, it fulfills
the practical requirements of demonstrating distinction from any
comparable species and ensuring that better specimens, when found,
can be securely determined as of this species.°° The occurrence of
three essentially similar specimens from three different localities and
horizons, but all within this field and all in the No. 2 beds, covering
a short span of time, also seems to demonstrate the validity and con-
siderable range of the species.
U.S.N.M. no. 9861 is a broken incisor from the Silberling Quarry
and no. 9705 a similar specimen from Loc. 51. Their dimensions,
given below, agree closely with those of the type.
In maximum diameter these teeth approach FE. americanus primus
and are significantly smaller than other comparable species. In
minimum diameter they are somewhat less and in compression ratio
4° Sparsus, scattered, from the dispersion of the scantly known remains of the species.
50 Such specimens are almost surely included in the American Museum collection, but they are not yet
prepared, and in any event it is proper that types be from the older collection, as far as possible.
119212—37——_8
104 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
significantly more than F. a. primus. The minimum diameter is about
that of E. teilhardi, but the maximum diameter and the compression
are significantly less. HH. americanus and E. molestus have the incisors
significantly larger in both diameters and the compression less. Exact
comparison with E. gratus Jepsen is not possible, but the incisor
alveolus of that species measures 2.7 by 1.1 mm, ratio 2.45. The
alveolus, and of course therefore the incisor as well, are much smaller
than the incisor of EL. sparsus. No known species aside from the
several now mentioned could well be so closely related to EH. sparsus
as to demand differentiation.
TaBLE 21.—Comparison of data on lower incisors of Eucosmodon
Diameters
Species and specimen ——_—_—_—_______—_————_} Ratio
Maximum |} Minimum
Mm Mm
RC INETUCON US AU YD Cs ee er ey eee 6. 0 296 Dar,
MOT DTLMUS ApalTaAly pes. a2 ee ae eee ee eee am 4,2 1.9 2. 21
EE AMmolestus, MOLY Pe! -< = ashe as oe ee Soe 5. 8 2.6 2. 23
Evtedhardt, paratypes. Use to seals ees eee 52 1.6 3.25
Mean Sih i274 Sees tae ree eg Mal 4,3 15 2. 70
OURS Seo Bt ek Le a ree oe eee 4.0 1.4 2. 86
PODORMEN Gin: eee Yh Oc A A pe ee 41 16| 2.56
OSGi oe nico be ee Sans cern seas 4.0 easy 2. 67
(#.. graius, type, from alveolus) sa. eee (O26) (1. 1)/(2. 45)
The original of Douglass’ plate 1, figures 18 and 20, probably belongs
to this genus. If the scale of the figure is accurate (which is not
invariably true in cases where J have studied Douglass’ originals), the
maximum diameter is about 3.7 mm, smaller than other specimens
referred to this species, to which the specimen may nevertheless
belong.
Order INSECTIVORA Gray, 1827
Forms that are at least nominally referable to the Insectivora con-
stitute an important element in Paleocene and Eocene faunas, and
this is particularly true in faunas, like that here described, in which
the microfauna is well or disproportionately represented. ‘They are
abundant in the present collection, including at least 10 species, all
of which occur together in the Gidley Quarry.
Despite diverse specializations, such as in the incisors of the Sori-
coidea or the limbs of the Talpoidea, the recent insectivores are on
the whole the most primitive of living placental mammals. The
characters common to all of them, excluding the specializations of
various particular phyla or larger groups, are in general those unques-
tionably primitive for all placental mammals. The conception of
the order and its definition thus do not so much depend on special
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 105
characters developed within the order as on characters also basic
for other orders but generally lost or more profoundly modified in
those orders. Indeed the outstanding ordinal character of the
Insectivora, paradoxically, is the absence of ordinal characters, in
the sense that these are developed in other groups.
Although the order is thus necessarily more loosely knit than is
usual, it does not follow that it is altogether artificial. The retention
of so many primitive characters is in itself some indication that this
conservative group may have still been somewhat unified after the
more progressive orders had acquired their distinctive characters.
Furthermore, there are a few characters, such as those noted by
Matthew in the astragalus, not of wholly generalized placental
pattern and distinctive of the Insectivora as against many or most
other mammals. There are also some characters, like the peculiar
specializations of the incisors, that do not occur in all insectivores
and are occasionally paralleled in other orders but that nevertheless
appear so frequently among insectivores that they seem to reflect a
certain genetic tendency and to help to bind the group together.
Every individual living insectivore is a specialized animal, each
species in its own way, and none can be considered, even structurally,
as really representing the general placental ancestry in any very
exact sense of the words. Yet the abstract conception Insectivora
based on all known forms is such that it would, almost perforce,
include the most primitive placental mammals. Probably the most
remote ancestors (in the Cretaceous) of most, perhaps of all, the
placental orders would be referable to the Insectivora by definition.
In this sense the order Insectivora is prototypal and ancestral to all
others among the Placentalia.
Because the ordinal characters of the Insectivora are mainly primi-
tive and because most of the Paleocene mammals are primitive,
almost all known Paleocene forms resemble the Insectivora in many
respects. If we knew the archaic mammals of the Paleocene but had
no knowledge of any of the forms that lived between that time and
the Recent, it would be a much more logical and practical system to
refer almost all Paleocene mammals to the Insectivora,” rather than
to distribute them in numerous different orders as is now the usual
practice. This distribution, in accordance with a “vertical” or so-
called evolutionary conception of classification, is accomplished by
the recognition of fossils intermediate between the Paleocene groups
and the more distinctly separated later orders and of incipient speciali-
zations within the Paleocene groups themselves that point toward
groups later to become so distinct that they are granted ordinal rank.
31 This is approximately the sense of Cope’s Bunotheria, a broad group including the Insectivora and
-various other primitive mammals. Cope did, however, separate and distribute among other orders some
Paleocene mammals, such as the Condylarthra, that were on the whole as primitive as those included in
-the Bunotheria.
106 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
The concept Insectivora as it is applied to the Paleocene (and
Eocene) faunas may thus include four different sorts of lesser groups:
1. Very primitive placentals whose ancestral relationship to other
later groups is not now recognizable. Naturally we do not know
what groups may be included here, for the only way in which this
situation could be shown to exist would be by recognition of the rela-
tionships, but probably some so-called insectivores are of this char-
acter.
2. Animals that are in fact in or near the ancestry of later more
specialized insectivores and that are therefore Insectivora sensu
stricto. The Nyctitheriidae probably belong in this category, al-
though the relationship is not definitely established. The other
families in the present fauna almost surely are not Insectivora in
this special and most limited sense.
3. Animals not structurally representative of the ancestry of later
insectivores but sharing certain specializations with them that seem
to indicate that they arose from a common stock with the later groups
after the definite differentiation of that stock. These are also to be
considered as Insectivora in a strict sense, even though the usage is
broader than it is as applied to the second category. The degrees of
such collateral relationship vary greatly. Thus the Leptictidae fail
definitely in this category, as they share many and apparently sig-
nificant special characters with the Erinaceidae, although clearly not
ancestral to that family. The Pantolestidae likewise show evidence
of a special collateral relationship to the later insectivores, but the
resemblance is less particular and the relationship evidently more
remote.
4. Groups that were derived from the nominally insectivore pro-
toplacental stock but that had begun to diverge markedly from any
other groups, without, however, having a sufficiently long history,
being sufficiently important faunal elements, or acquiring sufficiently
striking special characters to warrant the erection for them of a
special order. Such groups are clearly Insectivora only in a very
broad sense, yet their exclusion from the order would be a needless
complication of taxonomy. The Mixodectidae appear to belong to
this category.
In this fauna there are 10 genera that are referable to the Insectivora
in the general sense here accepted. Gelastops is evidently related to
Didelphodus of the Lower Eocene and Acmeodon of the Middle
Paleocene. It is perhaps a modified survivor of the protoplacental
stock. Prodiacodon and Leptacodon are typical leptictids, Myrmeco-
boides is an aberrant member of that group, and Bessoecetor is a primi-
tive but typical pantolestid, while Aphronorus constitutes with the
Torrejon Pentacodon a more aberrant group probably of pantolestid
origin. Eudaemonema seems surely to be a mixodectid, although
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 107
phyletically distinct from any other known genus. Picrodus is really
of unknown affinities and is placed in the Insectivora only in default
of other evidence.
Family ?7DELTATHERIDIIDAE Gregory and Simpson, 1926
Subfamily DIDELPHODONTINAE Matthew, 1918
Matthew placed this subfamily in the Leptictidae, pointing out
that the affinities of Didelphodus are uncertain, but that it ‘‘can not
easily be placed in any other family.” Except for the general state-
ment that ‘‘the teeth are in many respects not unlike those of the
Leptictidae’’, he gave no definite reason for placing Didelphodus in
that family, where it was decidedly anomalous. In defining the
Deltatheridiidae, Gregory and Simpson (1926) stated that Didelphodus
might belong in that group, and I still later (Simpson, 1928) gave in
somewhat more detail the reasons for this tentative assignment.
Gelastops of the present fauna is sufficiently close to Didelphodus
to warrant their tentative collocation in one subfamily but, as brought
out more fully in describing Gelastops, this is not certain. In any
case Gelastops is poorly known and adds little to evidence for the
affinities of this group. Its more aberrant premolar structure, still
more striking in the probably allied Acmeodon, does to some extent
argue against close affinities with the much more primitive Cretaceous
forms but this may merely indicate an incipient line of specialization
within the Deltatheridiidae. The data do not warrant a more positive
conclusion. On present evidence it seems well to retain Matthew’s
subfamily Didelphodontinae, for Didelphodus, Gelastops, Acmeodon,
and probably Phenacops. This necessitates the proposal of a new
subfamily Deltatheridiinae, defined, among other characters, by the
less progressive premolars, less separated paracone and metacone, and
narrower talonids.
Genus GELASTOPS Simpson
Gelastops Stimpson, 1935d, p. 227.
Emperodon Simpson, 1935d, p. 229.
Type.—Gelastops parcus Simpson.
Type of Emperodon.—Emperodon acmeodontoides Simpson.
Mistribution—Middle Paleocene, Fort Union, Mont.
Diagnosis.—Canine large and erect. P, intermediate in structure
between Didelphodus and Acmeodon, with paraconid high on crown,
metaconid nearly as high as protoconid and partly confluent with
latter, a vertical crest descending posteriorly from the metaconid and
another from the protoconid, and a small, bicuspid, basined talonid.
Molars leptictid or didelphodontine, paraconids large and more inter-
nal than in Prodiacodon or similar leptictids, trigonids elevated, that
108 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
of M, large relative to talonid and those of M,.3; compressed antero-
posteriorly. M, and particularly M3; reduced relative to M,, heel of
M; much reduced but with projecting hypoconulid.
Discussion—By an unfortunate chance the National Museum
material of this unusual genus does not include associated P, and M,.
Since P, seems clearly related to Acmeodon, while M, seems just as
clearly related to Didelphodus, and since the possibility of relationship
between Acmeodon and Didelphodus had never been suggested, I was
led to believe that two different animals were represented, one related
to each of these genera. Specimens collected since this manuscript
was first completed show that the P, supposedly characteristic of
Emperodon and the M, supposedly characteristic of Gelastops really
belonged to the same animal and this has made possible a last-minute
correction in the present work.
There is little doubt that Gelastops is related to Acmeodon, although
it is, on the whole, more primitive in structure. It had the anterior
premolars less reduced than in the latter. P, is superficially quite
different in the two genera, but the differences appear to be modifica-
tions of the same fundamental structure, which is unlike that of any
other genera known tome. In Gelastops the paraconid is larger and
more internal and the metaconid is distinct, but the latter is prob-
ably represented in Acmeodon by the cuspule on the posterointernal
crest descending from the protoconid, in which case the distinction is
the relatively minor one that in Gelastops this cuspule is merely more
emphasized and shifted slightly anteriorly. The peculiar protostylid
is larger in Acmeodon but is also present in Gelastops. In Acmeodon
the two crests run into the talonid rim and the valley between them
into the talonid basin in such a way that the talonid is poorly differen-
tiated, while in Gelastops the talonid is well set off by notches, but
the parts seem to be entirely homologous in the two cases. The
large and internal paraconid and talonid markedly narrower than
trigonid, which so strikingly separate Acmeodon from the Leptictidae,
are developed in almost exactly the same way in Gelastops.
On the other hand, there is also good evidence for the relationship
of Gelastops to Didelphodus. The general aspect of the jaw, canine,
and cheek dentition is much the same in the two genera. In Gelas-
tops P, is probably more reduced and P,-, more elevated. Py, is
definitely more specialized in Gelastops than in Didelphodus, having a
higher crown, more elevated (but little larger) paraconid, larger and
much more elevated metaconid, and more prominent posterior crest
on the metaconid. This crest is, however, distinctly present in
Didelphodus and in general all the structural features seem to corre-
spond in the two genera, the differences involving only relative
proportions and prominence of the various parts.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 109
The lower molars of Gelastops so closely resemble those of Didel-
phodus as to make a hypothesis of relationship most reasonable.
The only really clear difference is the greater elevation of the trigo-
nids in Gelastops and this is not extreme. The upper molar men-
tioned below also adds to the evidence, but the reference is not
certain.
Gelastops thus resembles both Acmeodon and Didelphodus and is
structurally almost intermediate between the two. Without pro-
ducing absolute proof, it strongly suggests that the three genera
Didelphodon, Gelastops, and Acmeodon belong to a natural group,
and they are here tentatively recognized as constituting the sub-
family Didelphodontinae. There are still difficulties in the way of
this interpretation that perhaps can be resolved only by the discovery
of upper dentitions of Gelastops and Acmeodon. The outstanding
difficulty is that the series Didelphodus-Gelastops-Acmeodon is an
excellent structural sequence in that order, on the basis of the parts
now known in all, but that the most primitive genus, Didelphodus, is
the latest in time, a relationship that is fully possible but that re-
quires better evidence for definitive acceptance.
GELASTOPS PARCUS Simpson
Figures 12, 13
Gelastops parcus Simpson, 1935d, p. 227.
Emperodon acmeodontoides Simpson, 1935d, p. 229.
Type-—U.S.N.M. no. 6148, right lower jaw with canine, M,, Msg,
and alveoli. Collected by A. C. Silberling.
Type of Emperodon acmeodontoides.—U.S.N.M. no. 9850, right
lower jaw with P,, M;, and part of P;. Collected by A. C. Silberling.
Horizon and locality—Type probably from Silberling Quarry,”
other specimens from Gidley Quarry, Fort Union, Middle Paleocene
horizon, Crazy Mountain Field, Mont.
Diagnosis—Sole known species of genus. Measurements in table 22.
Remarks.—Besides the type and that of the synonym, there are
two referred specimens from the Gidley Quarry in the National
Museum collection: U.S.N.M. no. 9601, a right lower jaw with
M,_; and alveoli, and U.S.N.M. no. 9446, a right lower jaw with M>-3.
From the alveoli it appears that a reduced P; was present; this
tooth is absent in Acmeodon and unreduced in Didelphodus. Po-3
were present and each had two well-separated roots. The structure
of P, has already been sufficiently described except to note that the
protoconid tip bends outward (labially) in a peculiar way, approach-
82 There is some inconsistency in the available records. It is certain that the type is from the Fort Union
No. 2, and from its preservation it must be from one of these two quarries, but some error or omission had
been made in recording the field number. Being collected in 1908, it is more likely to be from the Silberling
Quarry.
110 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
ing Acmeodon, its outer wall looking as if it had been plastically de-
formed by pressing the apex outward. Except for details in the
generic diagnosis or evident from the measurements, the lower molars
so closely resemble those of Didelphodus absarokae, described by
Matthew (1918), that further description of them is not necessary.
There is a single left M?, U.S.N.M. no. 9554, from the Gidley
Quarry, that may belong to this species, although it differs more
markedly from Didelphodus absarokae than do the lower molars. It
is remarkably short and wide, or extremely transverse, and further
differs from Didelphodus in the great extension of the parastyle spur,
the slightly more external position of paracone and metacone, and the
vestigial character of the metaconule. It resembles Didelphodus in
other respects, such as the emarginate outer border, shelf-like meta-
FIGURE 12.—Gelastops parcus Simpson, U.S.N.M. no. FIGURE 13.—Gelastops parcus Simpson:
6148: Right lower jaw, external view. Twice natural a, Crown view of right lower teeth
size. and alveoli, U.S.N.M. no. 9601; 6,
internal view of right lower jaw, U.S.
N.M. no. 9850. Twice natural size.
stylar extension, connate bases of paracone and metacone, and entire
absence of hypocone or of anterior or posterior cingula. The trans-
verse extension and the reduction of the metaconule are, furthermore,
Didelphodus-like but here more extreme and the nonmarginal position
of paracone and metacone are also Didelphodus-like but less pronounced.
TABLE 22.— Measurements of individual specimens of Gelastops parcus.
1a M, M3 M; M2?
U.S.N.M. no.
L W L W L WwW L WwW L Ww
Mm|Mm|Mm|Mm|Mm|Mm)|Mm|Mm|Mm\|Mm
O48 Yee Sree se oe ae ose Sree | ee cae 3. 5 7 Yall eee | eee 2.9 180252228 Sacer
O44 6 Be 2 rate an Sees ot Ea een See. Ree eee ee eed ee oe 2.5 2.0 PA 1.9
OR SORE Se ee ee es ee ee Ee ees Fe. 2.8 JQ) [sae healer ae 2.9 2.2
10) LS pa es ee ee ee ell (ee See | eee BLOM) 253) | 289) ) = 19.
O55 aes hee, OU Sees Pay i ee Ee en ke Oe 2k | Ee eee eee Pst 5.0
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. skal
Family LEPTICTIDAE Gill, 1872
Unlike many of the Paleocene and Lower Eocene groups referred
to the Insectivora, the Leptictidae are Insectivora sensu stricto. That
is, they are not merely primitive forms that are presumed to have
been derived from an undifferentiated insectivore stock and that do
not enter well into any other order, but are definitely insectivores in
a special sense, clearly related to recent insectivores. Their affinities
seem to be with the erinaceoids, although here they constitute an
extinct side line, not ancestral to the true Erinaceidae. More exact
elucidation of their affinities depends on full analysis of the characters
of the Oligocene forms, which are known from nearly complete
skeletons but have never been adequately studied.
Matthew (1918) has pointed out that there is a group of genera
undoubtedly leptictid (now about nine genera) and that in addition
to these there are several diverse genera placed here without much
positive evidence but in default of other indications. Didelphodus,
Phenacops, and Acmeodon, then placed here by Matthew, are now
TABLE 23.—Comparison of lower dentition of five genera of Paleocene Leptictidae
Genus Canine Py Trigonids Molar paraconids Ms; talonid
Diacodon_-_.--- Small_.| With sharp, low, median | Trigonids of Ps- | Lower than other | Elongate.
paraconid. Protocon- M; moderate- trigonid cusps,
id and metaconid op- ly elevated. small, submedi-
posite and _ nearly an.
equal. Heel basined,
with 3 cusps, hypo-
conid largest and near-
ly confluent with hy-
poconulid.
Prodiacodon_..| Large..| With trigonid similar to | Trigonids of Psi- | About asin Diaco- | About as in
Diacodon. Talonid M; strongly don. Diacodon.
with hypoconid rela- elevated.
tively less dominant,
hypoconulid more sep-
arate, sometimes with
4 distinct talonid cus-
pules.
Leptacodon__.-| Large_-| Closely similar to Diaco- | Little elevated..| Nearly internal, | Short.
don, but metaconid otherwise more
smaller, usually pos- like Diacodon.
terointernal to proto-
conid. Talonid small.
Myrmecoboides_| Moder- | Elongate, trigonid sim- | Moderately ele- | Small but nearly | Very elon-
ate. ilar to Diacodon. Tal- vated. as high as meta- gate.
onid long, narrow, ba- conids, fully in-
sined, without dis- ternal, fusing
tinet hypoconulid, en- with metacon-
toconid about equal to ids.
hypoconid.
Xenacodon_..-- Small__| With small basal para- |_-___ (0 (oe ee About intermedi- | Short, strong-
conid, large metaconid. ate between ly reduced.
Talonid very short, Diacodon and
not basined. Leptacodon.
112 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
tentatively removed to the Deltatheridiidae. The genus of most
doubtful affinities still retained in this family is Yenacodon Matthew
and Granger, of the Tiffany.
The more positively leptictid genera Diacodon, Prodiacodon,
Leptacodon, and Myrmecoboides also occur in the Paleocene, the last
three being represented in this fauna. Table 23 shows some of the
more striking distinctions in the lower dentitions of the five genera
recorded from the Paleocene.
Of these genera, Diacodon, Prodiacodon, and Leptacodon are typical
leptictids and are evidently very closely allied, to such a point that
they are rather difficult to distinguish. Myrmecoboides seems to be
a true leptictid but is highly distinctive and perhaps not closely
related to any of the more typical genera. Xenacodon is a distinctive
but poorly known and rather dubious form.
Genus PRODIACODON Matthew, 1929
PRODIACODON CONCORDIARCENSIS Simpson
FicureE 14
Prodiacodon concordiarcensis Stmpson, 1935d, p. 228.
Type.—U.S.N.M. no. 9637, left lower jaw with P., P., M3, and
alveoli. Collected by Dr. J. W. Gidley.
Horizon and locality —Gidley Quarry, Fort Union, Middle Paleocene
horizon, Crazy Mountain Field, Mont.
’
,
‘ V7"
\ A H)
SD
FIGURE 14.—Prodiacodon concordiarcensis Simpson, U.S.N.M. no. 9637, left lower jaw: a, Crown view;
b, internal view. Five times natural size.
Diagnosis —Much smaller than Prodiacodon puercensis. P, with
paraconid more secant and projecting more anteriorly, talonid with
three conical cusps, hypoconid largest and entoconid smallest. M3
with trigonid more slender and markedly elevated, talonid less
elongate, with three subequal cusps.
Remarks.—P, has a high but small paraconid and low posterior
cuspule. The horizontal ramus is very long and slender, and the
anterior teeth were evidently procumbent.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 113
This delicate species differs so much from Prodiacodon puercensis
that the generic reference is not at all certain, but the only alternative
would be erecting a new genus, which is highly undesirable at present.
The present form is apparently a typical leptictid, peculiar only in
minute details, and as close to Prodiacodon as to any other defined
genus. It is almost equally close to Leptacodon, but its reference
there would make the generic definitions almost impossible to frame
adequately.
The type is the only known specimen. Its dimensions are as
follows: Length P., 1.3; width P,, 0.5; length P,, 2.0; width P,, 1.1;
length M;, 1.9; width Ms, 1.2.
Genus LEPTACODON Maithew and Granger, 1921
LEPTACODON LADAE Simpson
Figure 15
Leptacodon ladae Simpson, 1935d, p. 228.
Type.—U.S.N.M. no. 9640, right lower jaw with Py-M;. Collected
by A. C. Silberling.
Horizon and locality Gidley Quarry, Fort Union, Middle Paleo-
cene horizon, Crazy Mountain Field, Mont.
FIGURE 15.—Lepiacodon ladae Simp- FIGURE 16.—Leptacodon munuscu-
son, U.S.N.M. no. 9640, right lum Simpson, U.S.N.M. no.
lower jaw: a, Crown view; ), in- 9819, left lower jaw: a, Crown
ternal view. Five times natural view; 6, internal view. Five
size. times natural size.
Diagnosis.—Slightly larger than L. tener or L. packi and slightly
smaller than L. siegfriedti, structurally closer to the former two
species (subgenus Leptacodon) than to the latter (subgenus Leipsano-
lestes). P, elongate, paraconid median, metaconid very small but in
the same postion as in L. tener, talonid as in that species. Molar
paraconids smaller than in ZL. tener but distinct and internal. Hypo-
conulids of M,-3; more projecting than in L. tener. Talonid of M;
more elongate and entoconid smaller.
Remarks.—This species is referable to Leptacodon with very little
doubt. Although fairly common in the Gidley Quarry, the speci-
mens are all very fragmentary, and they add nothing to knowledge
of the genus beyond making it a little more varied.
114 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
The dimensions of the type are as follows: Length Py, 1.4; width
P,, 1.0; length M,, 1.5; width M,, 1.2; length M,, 1.4; width Mg, 1.3;
length M3, 1.5; width Ms, 1.1.
The available numerical data on the whole sample are given in
table 24.
TABLE 24.—Numerical data on specimens of Leptacodon ladae
Variate N R M o V
WGP ese eae 5 1.4—1.6 1. 48
Wile oe eee 5 0.8—1.0 0. 90
ING See ae Ss i 1.4—1.6 1. 53+0. 03 0. O07 40. 02 4,.6+1. 2
WIM joo. = 2 6 1.0—1.3 1.17+0. 04 0. 09+0. 03 8 142.3
1 NY ee pees ee 9 1.38—1.6 1.438+0. 03 0. 08 +0. C2 5 fe ded
Wags ee ee 8 0.9—1. 4 1. 20+0. 05 0. 14+0. 04 11.7+2.9
WMeo 2 Se ae 8 1.4—1.6 1. 51+0. 02 0. 06+0. 02 4.0+1.0
\ WNW iy ees € 1.0—1. 2 1. 09+0. 02 0. 06+0. 02 5. 941.6
1 BN Ge ee 3 4,5—4.7 4. 57
The two available specimens of L. tener are at or slightly below
the observed lower limits for Z. ladae in all molar dimensions. The
deviations of the four available dimensions of the type of L. tener
from the means of L. ladae, divided by the corresponding standard
deviations of the latter (d/c) are as follows:
LM;: —6.1 LM:: —4.0
WM;,:—5.0 WM:: —2.9
The size difference, slight as it is, thus appears to be significant.
Individual measurements of ZL. packi are not available, but that
species is very close to L. tener in size, hence probably also signifi-
cantly smaller than L. ladae.
LEPTACODON MUNUSCULUM Simpson
Figure 16
Leptacodon munusculum Simpson, 1935d, p. 228.
Type.—U.S.N.M. no. 9819, left lower jaw with M, and M;. Col-
lected by A. C. Silberling.
Horizon and locality Gidley Quarry, Fort Union, Middle Paleo-
cene horizon, Crazy Mountain Field, Mont.
Dragnosis.—M, of about the same size as in L. tener, M; more
reduced. Paraconids smaller and more strictly internal. Talonid
of Ms; relatively narrower.
Remarks.—This poorly known species is the smallest mammal in
the collection and is one of the smallest mammals known. It is
‘3 The original diagnosis says ‘‘Slightly smaller than Leptacodon tener’’, which was probably true of
the dentition as a whole and perhaps of the animal, but M1 is as large as in L. tener.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. £5
almost certainly referable to this genus but is shown to be a dis-
tinctive species even from the one very fragmentary specimen avail-
able. M, is 1.2 and M; 1.1 mm in length. The comparison with
L. ladae by d/o is thus as follows:
LM;:4.7 LM;:6.8
The ratio LM,/LM; compares as follows:
L. tener (referred specimen) : 0.86.
L. ladae (three specimens) :1.00—1.07, mean 1.05.
L. munusculum: 1.09.
M; is thus more reduced in ZL. ladae and in L. munusculum than
in L. tener. The difference between L. munusculum and L. ladae may
be, but is not shown to be, significant.
Genus MYRMECOBOIDES Gidiey
Myrmecoboides G1pLEY, 1915, p. 395.
Type.—Myrmecoboides montanensis Gidley.
Distribution.—Middle Paleocene, Fort Union, Montana.
Diagnosis —Canine of moderate size. Premolars well spaced.
P, elongate, with strong but low, median paraconid, metaconid well
separated and nearly as high as protoconid, talonid long and narrow
with small, subequal hypoconid and entoconid and hypoconulid
barely suggested. Molars, particularly M3, with long talonids and
with moderately elevated trigonids. Paraconids smaller than meta-
conids but nearly as high and partly connate, so that paraconid and
metaconid together form a twinned apex that is higher than the
protoconid.
Remarks.—Gidley stated that the name Myrmecoboides was “given
to the ancient form on account of its likeness to Myrmecobius rather
than as a positive assumption of real relationship.” He did, however,
state that the genus was marsupilalian and probably related to the
Myrmecobiidae, and he went into much detail regarding its bearing
on marsupial evolution. Abel (1919) placed Myrmecoboides in the
Myrmecobiidae. Osgood (1921) stated that Myrmecoboides might
well be ancestral to Caenolestes, if it wasa marsupial. Schlosser (1923)
classified it in the Myrmecobiidae but noted that it might not be mar-
supial. Longman (1924) gave a résumé of Gidley’s view, stating (as
had Gidley) that the resemblances to Myrmecobius were suggestive
but not conclusive. Matthew (1916) had, however, quickly pointed
out that the characters of Myrmecoboides are not myrmecoboid or
marsupial, but leptictid and placental. Gidley also came to accept
this conclusion (personal communication) but apparently did not
publish this fact. Students of Paleocene mammals have long realized
that Myrmecoboides cannot be a marsupial, but aside from Matthew’s
brief statement, which has been overlooked by almost all later com-
116 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
mentators, the evidence has not been clearly stated in publication and
Gidley’s abandoned view is becoming entrenched in the literature.
It is therefore necessary to consider it here.
Gidley did not explicitly discuss the evidence for referring Myrmeco-
boides to the Marsupialia. It is clear that the reference was based
almost entirely on the molariform character of the fourth cheek tooth,
and in part simply on a general resemblance to the one marsupial genus
Myrmecobius. Gidley mentions the three possibilities regarding the
molariform tooth: that it is a true molar, that it is a deciduous molar,
and that it is a true premolar. He cites the narrower crown, smaller
talonid, and large, anteriorly directed paraconid as seemingly preclud-
ing the possibility that the tooth is a true molar. This evidence is
valid, and to it may be added (as first pointed out by Matthew) the fact
that the protrusion and wear of the tooth definitely prove that it was
erupted long after the following tooth, which could not be true of a
first molar. Gidley states that the very complex structure in com-
parison with P; opposes the supposition that this 1s P, and supports
his conclusion that it is dm,, retained in the adult dentition. But the
relative time of eruption, as first shown by Matthew, is impossible for
dm,, which in all known mammals is erupted before M, rather than
long after, as the tooth in question is in Myrmecoboides. Further-
more, the fourth cheek tooth in marsupials, whether it be M, or dm,, is
erupted before the following tooth or at almost the same time. Gidley
also seems to have overlooked, momentarily, the fact well known to
him that in the Leptictidae and some other unquestionable placentals
P, is characteristically as molariform as this tooth, or more so, even
though P; may be as simple as in Myrmecoboides. It may be con-
cluded, and Gidley also did conclude on more mature deliberation,
that this is certainly P,, and hence that its evidence is entirely opposed
to marsupial and in favor of placental affinities for the genus.
Gidley analyzed all the resemblances to and differences from
Myrmecobius. The only resemblances that could be supposed to
carry much weight are the spacing of the premolars and the elevation
of the internal cusps of the molars. These characters also do occur in
placentals and are highly aberrant among marsupials. These, and all
the other lesser points of resemblance, would perhaps tend to link
Myrmecoboides to Myrmecobius if the former were otherwise proved to
be a marsupial, but they have no value as to the primary question of
showing it to be marsupial. There are indeed profound differences
between the fossil and Myrmecobius. Gidley recognized these but con-
cluded that degeneration could lead to this great transformation, which
is true but is not evidence that it did so. On the other hand, Myrmeco-
boides has the basic and diagnostic characters of the Leptictidae, and the
Myrmecobius-like characters can only be interpreted as superficial, aber-
rant, habitus characters bringing about a slight degree of convergence.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 117
The fact that Myrmecoboides is not a marsupial obviously deprives
it of any bearing on whether the fourth cheek tooth of marsupials is
dm, or M,, a question that Gidley properly discussed when under a
misapprehension as to the affinities of the genus. It also removes this
much support from Gidley’s thesis, which was, however, also sup-
ported by other evidence, that the Australian families were differen-
tiated outside Australia and at a very early date.™
Among the Leptictidae, Myrmecoboides is aberrant and does not
belong with such typical genera as Diacodon or Leptacodon, although
its less direct relationship with them is highly probable.
MYRMECOBOIDES MONTANENSIS Gidley
Figures 17, 18
Myrmecoboides montanensis G1pLEY, 1915, p. 395.
Type.—U.S.N.M. no. 8037, left lower jaw with canine and P,—Ms3.
Collected by A. C. Silberling.
Horizon and locality —Gidley Quarry, Fort Union, Middle Paleo-
cene horizon, Crazy Mountain Field, Mont.
Diagnosis—Sole known species of genus. Dimensions below.
Remarks.—Gidley (1915) has accurately described the lower denti-
tion, and the slightly different emphasis demanded by transfer to this
family is supplied by the revised generic diagnosis. The second spec-
imen mentioned by Gidley is U.S.N.M. no. 9418, which has only M,.»
and these so worn that the cusp structure cannot be made out.
U.S.N.M. no. 9552 is a right upper jaw with P*-M? that is so well
suited to be the upper dentition of Myrmecoboides montanensis, and
not of any other known species in the fauna, that it may be referred
here. Dr. Gidley has noted that this is probably the upper dentition
of Myrmecoboides—further evidence of his later recognition of the
affinities of the genus, for this upper jaw is entirely leptictid in char-
acter and does not at all resemble Myrmecobius. These upper teeth
are very close to those of Prodiacodon throughout. P* seems to have
had the paracone and metacone better separated in Myrmecoboides,
but is imperfect in this region. Ml! has the external shelf more pro-
nounced, the parastylar and metastylar lobes more projecting, a deep
§4 When Gidley wrote, it was a reasonable a priori assumption that diverse marsupials would be the micro-
faunal elements most likely to appear in the Paleocene, although subsequent discovery has shown this not
to be the case. He was inevitably predisposed toward this view (as was also Matthew and as were other con-
temporaneous students), and his preliminary note on Myrmecoboides suffered from this preconception. It
is further exemplified by his manuscript notes on several other placental genera labeled as ‘‘Marsupial No. 1”
and so on; it has not seemed necessary to cite this first impression in each case, as Dr. Gidley would certainly
have abandoned it before completing his studies. Dr. Gidley also had a strong and more personal predis-
position, strikingly exemplified in the Myrmecoboides paper, to believe that the modern mammalian families
were of extremely remote origin. This is a legitimate thesis, and the erroneous nature of part of the supposed
evidence does not remove the possibility or vitiate Gidley’s whole argument. His conclusion unquestion-
ably contains an important truth, but I believe, apparently with the consensus of recent students, that he
overemphasized its importance and extent.
118 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Se, 2 “I Wines
BG UK BN Rs eB
AN YS By
Ego =P
5 Zp”
FIGURE 17.—Myrmecoboides montanensis Gidley, U.S.N.M. no. 8037, left lower jaw: a, Crown view: 6, in-
ternal view. Four times natural size.
FiGuRE 18.—Myrmecoboides montanensis Gidley, U.S.N.M. no. 9552, right upper P‘-M3, crown view. Four
times natural size.
median notch in the external border, and the hypocone more internal.
M? has the outer portion analogously modified, but this is less dis-
tinctive from Prodiacodon than is M!. M* is of almost identical struc-
ture in the two genera.
TABLE 25.—Measurements (in mm) of the type and of the referred upper jaw of
Myrmecoboides montanensis
Pi P2 P3 Py Mi M2 M3 Pt MI! M? M3
p(wiulwiolwie|wielwi[s]w[olw/o|wlelwie w]e] w
ee | se | | | J | | | | i [J | es | eee lt
1.1) 0.6} 1.8] 0.8) 2.3) 0.9) 2.7) 1.3) 2.4) 1.5) 2.3 4a 2. 6) 1. 5) 2.6] 3.3) 2.3] 3.7 24 3.8} 2.0) 3.7
|
Family NYCTITHERIIDAE Simpson, 1928
This family was established to include a number of rather poorly
known Paleocene and Eocene genera, all represented by species of
small or minute size, that probably represent a single varied group
and that seem to be primitive shrewlike insectivores, without any of
the specializations characteristic of the true shrews. In this respect
the dentition is molelike rather than shrewlike, but there is no evi-
dence of definitely talpid specializations. As Matthew (1909) has
pointed out (in other words), speaking of Eocene genera that I have
since placed in this family, they seem to combine all the most primi-
tive characters of the moles and the shrews. To this extent the evi-
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 119
dence suggests an undifferentiated group from which these late insec-
tivores arose, but annectant types are lacking and knowledge is too
incomplete to test this hypothesis adequately. Matthew (1918) has
also pointed out that Nyctitherium itself may be a chiropteran, and
this may be true of the whole group, or it may be a primitive complex
allied or ancestral to all three groups, Talpoidea, Soricoidea, and Chir-
optera, although there is reason to suppose that these three groups
were already distinct before the end of the Paleocene. It is likewise
possible that two or all three of these groups had acquired their skel-
etal specializations but not their dental characters in the Paleocene
and that the nyctitherids are an artificial assemblage based on dental
resemblance only. Despite this possibility, it seems most practical to
continue to associate them in this family until some broader basis for
classification becomes available.
FIGURE 19.—Stilpnodon sjmplicidens Simpson, U.S.N.M. no 9629, left lower jaw: a, Crown view; 6, internal
view. Five times natural size.
In the National Museum collection only one nyctitheriid specimen
is available, but it represents a distinctive genus, Stilpnodon. It
is not very close to any other known genus, and its reference to the
family is not certainly established, but it is most conveniently placed
here. It shares with Leptacodon munusculum the distinction of being
the smallest known mammal of this fauna.
Genus STILPNODON Simpson
Stilpnodon Simpson, 1935d, p. 229.
Type.—Stilpnodon simplicidens Simpson.
Distribution.—Middle Paleocene, Fort Union, Mont.
Diagnosis.—P, with very high, slender main cusp, minute rudimen-
tary anterior basal caspule, no metaconid, simple nonbasined talonid
with one cuspule. M; reduced, with distinct, low, nearly median
paraconid, trigonid erect and moderately elevated above talonid,
protoconid large, trigonid nearly as long as talonid, talonid short and
much narrower than trigonid.
119212—387 9
120 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
STILPNODON SIMPLICIDENS Simpson
Figure 19
Stilpnodon simplicidens Simpson, 1935d, p. 229.
Type.-—U.S.N.M. no. 9629, left lower jaw with P34, M3, and
alveoli.
Horizon and locality —Gidley Quarry, Fort Union, Middle Paleo-
cene horizon, Crazy Mountain Field, Mont.
Diagnosis.—Sole known species of genus. P,length, 1.0mm. Ms;
length, 1.2 mm.
Remarks.—P; is very simple, without anterior basal cuspule and
with the sloping heel not forming a distinct cusp. From its roots,
P, was of about the same size as P;. The posterior mental foramen
is beneath the anterior root of P,.
Family PANTOLESTIDAE Cope, 1884
In his Bridger memoir Matthew (1909) united various genera pre-
viously widely scattered in the system and placed them in the Pantoles-
tidae. From a study of Pantolestes, a relatively specialized but well-
known Middle Eocene genus, he showed that at least the typical
members of the family have basic insectivore characters, overlain by
peculiar specializations not closely paralleled in recent insectivores.
He interpreted the majority of these specializations in Pantolestes as
adaptations to aquatic, or to amphibious, life. At that time he pointed
out that Palaeosinopa, then known from the Lower Eocene, is closely
related to Pantolestes and that Pentacodon, of the Middle Paleocene,
might tentatively be placed in this family. In 1918 Matthew revised
and carefully described the Lower Eocene Palaeosinopa, again
emphasizing its close relationship to Pantolestes, and reviewed the
evidence for reference of these genera to the Insectivora. This
evidence, which still appears to be adequate for such a conclusion is,
in briefest possible outline, that the pantolestid dentition is, indeed,
more creodontlike than like any recent insectivore but is also closely
similar to the unquestionably insectivore leptictids, and that numerous
characters of skull and skeleton (especially the astragalus) are quite
unlike any known creodonts or other carnivores but do resemble the
Leptictidae and other Insectivora. A special point of the evidence
(singled out by Schlosser, see Matthew, 1918, for undue emphasis)
is the position of the posterior mental foramen beneath M,, a character
known only in Insectivora, although not characterizing all members
of that order.
Various fragments suggested the presence of this family in the
Upper Paleocene (e. g., Simpson, 1927), and Jepsen (1930a) referred a
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. P20
partial jaw from the Middle Paleocene to Palaeosinopa. I have
described a genus, Bessoeceter, from the Upper Paleocene (Simpson,
1936b). The present fauna includes a distinctive species that seems
surely to be closely allied to or in the Palaeosinopa—Pantolestes line
and is tentatively referred to Bessoecetor, thus definitely projecting
the typical pantolestid phylum back into the Middle Paleocene. It
also includes in Aphronorus an ally of Pentacodon, represented by
much better material than is that Torrejon genus and much improving
our knowledge of this small group.
The probable relationship of Pentacodon and Aphronorus, on one
hand, and Bessoecetor, Palaeosinopa, and Pantolestes, on the other, is
confirmed and strengthened by the present evidence. In both the
lower jaw has a large semiprocumbent canine followed by three small
elongate premolars of similar pattern in the two groups and then by
a relatively enlarged premolar, the pattern of which is, however,
unlike in the two lines. The molars, upper and lower, are of almost
exactly similar pattern, with only such minute differences as are
encountered among very closely allied genera. The posterior mental
foramen is beneath M, in both cases and the other known osteological
characters, although few and not very distinctive, are generally
similar.
The only characters opposing such relationships are those of P*j,
which are more and differently specialized in Pentacodon and Aph-
ronorus than in Bessoecetor or even the much later genus Pantolestes.
These marked differences do not seem to exclude a family relation-
ship, but they do show that two divergent and sharply defined groups
are included, especially when the distribution of the various genera is
taken into account. In the present state of knowledge it seems
convenient to formalize this distinction by placing the known genera
in two subfamilies, the Pantolestinae with Bessoecetor, Pantolestes,
Palaeosinopa, and perhaps some less well known forms, and the
Pentacodontinae with Pentacodon and Aphronorus. For the present
these are immediately and adequately distinguishable from the
characters of P*, as given in the diagnosis below.
PANTOLESTINAE, new subfamily
Type.—Pantolestes Cope, 1872.
Distribution —Middle Paleocene to Middle Eocene, North America.
Lower Eocene, Europe.
Diagnosis —P*, relatively little enlarged. P, compressed, no
metaconid, semishearing, heel essentially unicuspid and little or not
basined. P* with compressed amphicone, no metacone, low, sharp
styles, small protocone without cingula.
122 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Genus BESSOECETOR Simpson
Bessoecetor Simpson, 1936b, p. 9.
Type.—Bessoecetor thomsoni Simpson.
Distribution —Middle and Upper Paleocene, Fort Union, Montana.
This genus was based on an unusually good suite of specimens from
the Scarritt Quarry. Itis evidently very closely allied to Palaeosinopa
but seems to be slightly more primitive in several respects. The
species Palaeosinopa diluculi, previously recorded from the present
fauna (Simpson, 1935d, p. 230) appears to be more nearly related to
Bessoecetor and may be provisionally placed in that genus, although it
is too poorly known to reveal all the desired generic characters. Most
of the characters in which it differs from Lower Eocene species of Pal-
aeosinopa and which were therefore given as specific characters in the
original diagnosis are now shown by the fine material of Bessoecetor
wey , ha NZ)
)
"
ST {i "
FIGURE 20.—Bessoecetor diluculi (Simpson), U.S.N.M. no. 9810, with parts in outline added from U.S.N.M.
nos. 9312 and 9539, left lower jaw: a, Crown view; 0, internal view. Three times natural size.
thomsoni to be generic characters of Bessoecetor. This includes, most
notably, the strongly trenchant P, with large anterior basal cusp and
incipient basining of talonid, the relatively small expansion of the
hypocone shelves, and the less reduced M*. The Middle Paleocene
form also has the sharply distinguished molar talonid cusps character-
istic of Bessoecetor.
BESSOECETOR DILUCULI (Simpson)
Figures 20, 21
Palaeosinopa diluculi Simpson, 1935d, p. 230.
Type.—U.S.N.M. no. 9810, left lower jaw with P,-M,. Collected
by A. C. Silberling.
Paratype—U.S.N.M. no. 9553, left upper jaw with P*-M®? (some-
what broken). Collected by A. C. Silberling.
Horizon and locality —Gidley and Silberling Quarries, Fort Union,
Middle Paleocene horizon, Crazy Mountain Field, Mont.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT.
123
Diagnosis. —P, and M,-; significantly larger than in B. thomsoni, My
about same size.
elongate.
Heel of P, relatively larger, talonid of M; more
Amphicone of P* more compressed.
Remarks.—The dentition is closely similar to that of B. thomsoni,
fully described elsewhere (Simpson, 1936b).
TABLE 26.—Dentition measurements (in mm) of Bessoecetor diluculi
Py Mi M2 M3;
U.S.N.M. no.
L Ww L WwW L Ww L Ww
OSI eres. 222 ck | eee 1S) 2.4 1 ¢/ 2.5 2.0
OSM eee tot |e eee Ree ee RL Ree a 2. 6 2. 2 By Os 73S
OA A ee a ee | eee 1.4 2.3 be 2.7 2.0
Oi3)) a eee ee Ss 3. 2 1.3 27 1.8
Ps M! M? M3
U.S.N.M. no.
L WwW L WwW L Ww L w
Oo See Betas S| Beal pei PAC 3. 4 2.8 3. 8
OS neers ee eee Bae 2Grtlee Paya Al he se 2. 6 3. 5 2. 0 3.5
FIGURE 21.—Bessoecetor
diluculi (Simpson), U.S.
N.M. no. 9553, with part
in outline added from
U.S.N.M. no. 9585, left
upper jaw: a, External
view; 6, crown view.
Three times natural size.
y DS =) & aN CANN
6) See ‘3
yy N S As Ay if
ZZ TI NUN SUT a We
FIGURE 22.—Aphronorus fraudator Simpson, U.S.
N.M. no. 6177, left lower jaw: a, Crown view; 6,
external view. ‘Three times natural size.
PENTACODONTINAE, new subfamily
Type.—Pentacodon Scott, 1892.
Distribution Middle Paleocene (and doubtfully Upper Paleocene),
North America.
Diagnosis —P*, much enlarged. P, with very heavy protoconid,
sloping backward, well-developed metaconid, and basined heel.
P4
with massive, conical, paracone, smaller but sharply distinct metacone,
124 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
styles small or lacking, and large, low protocone with widely expanded
anterior and posterior cingula.
Remarks.—Aside from its probable relationship to the Pantolestinae,
this group shows some resemblance to the Anisonchinae and to the
Apheliscidae, but in neither case is this resemblance close enough to
suggest real affinity. The enlargement of P*, and the general but
primitive stamp of the molars is not unlike the Anisonchinae but
does not include any detail such as might indicate a real relationship.
P*, still more resemble those of Apheliscus but differ in cusp structure,
and the molars are widely different. It is not impossible that Aphelis-
cus is an offshoot of the same stock, but real evidence for such a hypoth-
esis 1s lacking.
Genus APHRONORUS Simpson
Aphronorus Simpson, 1935d, p. 230.
Type.—Aphronorus fraudator Simpson.
Distribution.—Middle Paleocene, Fort Union, Montana.
Diagnosis.—Generally similar to Pentacodon. P, with anterior end
less produced downward than in Pentacodon, talonid more distinctly
basined, with second cuspule more distinct. M,_3; less reduced
relatively toM,. Trigonids of M,_, relatively shorter and entoconids
relatively higher than in Pentacodon. Three talonid cusps of Mg,
more distinct. P* with metacone well differentiated, protoconule
distinct. M! and to less degree M? slenderer and more transverse
than in Pentacodon, more leptictid in aspect.
Remarks.—This genus is evidently closely allied to Pentacodon, and
its distinctive characters, taken together, do not definitely suggest
that it is necessarily either an earlier or a later stage in the Pentacodon
phylum. Evolution could have proceeded in either direction, or the
two may have diverged from a common ancestry. Nevertheless
Aphronorus does seem to resemble Palacosinopa in more details than
does Pentacodon and to this extent may be supposed to retain more of
of the primitive characters of the family as a whole, despite its possible
divergence in other respects.
APHRONORUS FRAUDATOR Simpson
Figurms 22-24
Aphronorus fraudator Simpson, 1935d, p. 230.
Type —U.S.N.M. no. 6177, left lower jaw with Py-M;. Collected
by A. C. Silberling.
Horizon and locality —Gidley and Silberling Quarries, Fort Union,
Middle Paleocene horizon, Crazy Mountain Field, Mont.
Diagnosis—Sole known species of genus. Dimensions given in
table 27.
Remarks.—The lower canine, known from its alveolus only, is large
and semiprocumbent. P,is very small and appears to have a single
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 125
root. P, is likewise small but more elongate and with two roots. The
only specimen that shows P,_2 is senile and these teeth are truncated
by wear at the bases of the crowns. P,; is larger than P, but also
small in relation to the whole dentition. When unworn it has a
triangular protoconid followed by a heel with a slight internal basin
and two rudimentary posterior cusps. P,is much enlarged and has a
massive protoconid, which slopes backward, and a lower distinct
metaconid, closely applied to the posterointernal base of the protoco-
eee
FIGURE 23.—Aphronorus fraudator Simpson, U.S.N.M. no. 9448, with parts in outline added from U.S.N.M.
nos. 9291 and 9519, right lower jaw: a, Crown view; b, internal view. Four times natural size.
Wan) /
: Git
\4
ev
STN
FIGURE 24.—Aphronorus fraudator Simpson, U.S.N.M. no. 9560, with tooth in outline added from U.S.N.M.
no. 9565, left upper jaw: a, External view; 6, crown view. Four times natural size.
nid. Anterior to this there is a sharp internal cingulum, turning into
a vertical crest at the anterior midline of the tooth, but there is usually
no paraconid or anterior cuspule, although in one or two specimens
there is a slight tendency to develop a cuspule here. The large heel
has its main cusp external to the midline, connected by a sharp crest
to the middle of the trigonid base. Internal to this crest is a basin, and
a second, smaller and less distinct cusp is near the posterointernal
corner of the tooth.
126 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
The lower molars decrease in size from M, to M;. The paraconids
are small and tend to assume a conical shape but are still connected to
the anterior protoconid crest. The paraconids are slightly internal
to the midline. Metaconids and protoconids are nearly equal. The
talonid is wider than the trigonid on M,, about equal on M3, and
narrower on M3. On M,.; the three talonid cusps are about equal in
height but the hypoconulid is smallest. On M,; the hypoconulid is
enlarged and projects posteriorly in the usual manner.
The mandible is lighter than in Pentacodon and very closely ap-
proaches Palaeosinopa in all respects.
P? is 3-rooted and has a single outer cusp like that of P* on a smaller
scale save for the absence of a metacone. The protocone is small, and
there are no cingula. P* is a peculiar, large, heavy tooth. Its con-
tour is hourglass-shaped, with median constriction and expanded
equal inner and outer lobes. The paracone is nearly circular in sec-
tion and is heavy and tall and slopes slightly backward, like the pro-
toconid of P,. It is followed by a smaller metacone. There is only
the vaguest rudiment of a parastyle, but a very small metastyle is
present. The protocone is crescentic and large but lower than the
paracone. There is a small protoconule and rudimentary metaconule.
Approximately equal and expanded anterior and posterior cingula
occur on the protocone base, and each tends to develop into a cuspule
(protostyle and hypocone). The upper molars are of leptictid type,
strongly transverse, with emarginate external shelves, projecting
parastylar and metastylar lobes (especially on M*), metacones slightly
smaller than paracones, conules distinct, anterointernal cingula, and
low hypocones slightly more internal than the protocones. M® is
reduced in the usual manner, with metastyle and hypocone absent and
metacone small.
TaBLE 27.—Numerical data on Aphronorus fraudator
Variate N R M o Vi
| i ey ee eee 10 3. 2-3. 8 3. 52+0. 05 0.17 +0. 04 4.9+1.1
WiRie so one 10 2. 0-2. 4 2.15+0. 05 0.14 +0. 038 6. 741.5
1 SY ee ae eee 10 2. 8-3. 1 2. 88 +0. 03 0. 098 + 0. 022 3.4+0.8
WiMisoss. 5... 10 1. 8-2. 4 2.18+0. 05 0.17 +0. 04 7.641. 7
Wipe ee 12 2. 5-2. 9 2. 6740. 04 0.13 +0. 03 4.7+1.0
WiiMote 232 11 1. 9-2. 4 2.17+0. 03 0. 114+0. 024 5. 2+1.1
BMeousreoet Uf 2. 6-2. 9 2. 79+0. 04 0.10 +0. 03 3. 5+0. 9
WM, .=-=-—- 7 1. 7-2. 1 1. 90+0. 05 0.12 +0. 03 6.3+1.7
1 Ey tat a ie 8 Py 2. 84+0. 06 0.18 +0. 05 6. 341.6
WIR Ace ne cece oe 8 3. 5-4. 3 3. 88+0. 08 0.22 +0. 05 56 641.4
Mts = = 8 2. 5-2. 8 2. 68+0. 03 0. 097 +0. 024 3.6+0. 9
Wail aa ea ee Gi 3. 6-3. 9 3. 80-40. 04 0.11 +0. 038 2.8+0. 8
Mtn oo seele 3 4 2. 2-2. 6 2. 43
Wiese oe 3 3. 9-4. 1 4. 00
CNS ee 2 1. 5-1. 9 1bea70)
Wi Meet ctr eas 2 3. 3-3. 6 3. 45
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 127
Family MIXODECTIDAE Cope, 1883
Previous views as to the affinities of this peculiar group have been
summed up by Matthew (1909, 1915, and Pale. Mem.). In briefer
résumé, Cope considered the mixodectids as primates. Matthew
(1897) concurred formally but suggested that Mizodectes itself might
rather be a rodent. Osborn (1902) accepted and expanded this view,
defining for the mixodectids a rodent suborder Proglires. Wortman
(1903) argued for their return to the Primates. Finally, Matthew
(1909 and subsequently) concluded that they probably belong in the
Insectivora.
Two very distinctive genera, Hudaemonema and Elpidophorus, have
recently been added to the family. They add to the known variety
and have an interesting bearing on relationships within the family, as
brought out below, but they do not much alter the evidence for ordinal
relationships.
Skeletal remains referred to Indrodon by Osborn and Earle and to
Microsyops by Wortman, in each case considered as indicating primate
affinities, have been shown (Matthew, 1909) to be doubtfully or not
associated. An astragalus and other fragments referred to Mizxodectes
were at first said by Matthew (1897) to be rodentlike and later (1909)
to be equally insectivorelike and in any case not similar to any known
primate.
The dentition is said, even by Matthew in rejecting primate affini-
ties, to be primatelike. There is, indeed, some resemblance to various
primate genera in a few details, for instance the upper molars suggest
Shoshonius in general proportions and in the strong mesostyle, and
the enlargement of one anterior tooth and development of a diastema
by loss of other teeth are also seen in Tetonius and some other genera.
Such resemblances seem to have no value in the determination of
affinities, since they refer to single characters of various different
primates that are, in just these characters, highly aberrant among the
primates as whole. Aside from such points, which can almost be
discarded categorically as more likely to be convergent than not, I
detect no primate resemblances in the teeth that go beyond the general
Paleocene tuberculosectional pattern common to many different
orders at this time. As set forth in the section of this paper dealing
with the Primates, the Paleocene and Eocene primates, despite their
primitive character, do have a distinctive stamp in molar pattern that
is common to all of them and that is not seen to occur in any other
order. The mixodectids do not have any of these truly distinctive
and (at this time) ordinal primate characters. On the contrary, their
high sharp cusps (notably in the talonids), elevated trigonids and
internal lower cusps, displaced hypoconulids, and many other dis-
tinctive details are quite unknown among any primates and some of
128 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
their family characters, such as the ectoloph construction, are ap-
proached only as decidedly aberrant generic characters by one or a few
primate genera.
If we grant Matthew’s second opinion that the astragalus of Mizo-
dectes does not have diagnostic ordinal rodent characters, the evidence
for rodent relationships is little more than the presence of enlarged in-
cisors and (in some but not all genera) of more or less molariform pre-
molars. Both these characters also appear independently in insecti-
vores, numerous different lines of ungulates, primates, marsupials,
end other orders. Nor are they really rodentlike in precise detail in
this group. Indeed, there now seems to be no actual evidence that
the mixodectids are related to rodents.
Granting the usage of Insectivora not only to include the recent
groups but also numerous extinct forms that necessitate definition on
primitive characters only, we may well call the mixodectids insecti-
vores. Negatively, it may be said that no other defined order could
receive them, and positively that their dentition is insectivorelike at
least in habitus, that the astragalus is more like that distinctive of
insectivores than like any other group except rodents (which are
excluded by the dentition), and that in general they have the primitive
features by which the Insectivora sensu lato are defined.
It is probable that the mixodectids include a related group of phyla
that diverged from the primitive placental stock, and apparently from
the Insectivora in a more limited sense, at a very early date. Had
such a sideline evolved more rapidly, or had it run a longer span and
occupied a more important place in mammalian history, it would be
more conveniently defined as an order, as, for instance, are the tillo-
donts, which probably had a very similar history but developed more
striking specializations. Since, in fact, the mixodectids were a short-
lived and relatively unimportant group, it is most convenient simply
to classify them in the order Insectivora, from which they probably
arose.
Within the Mixodectidae there have been included two apparently
distinct groups: Mizodectes and Indrodon of the Torrejon, on one
hand, and Cynodontomys and Microsyops of the Lower and Middle
Eocene, on the other. The Torrejon forms are certainly closely re-
lated, indeed the distinction between them is not clear, and the Eocene
genera are also closely allied and rather difficult to distinguish.
Matthew (1915c) defined the two groups as subfamilies, Mixodectinae
and Microsyopinae, and he repeatedly expressed doubts as to their
really being related to each other, rather than merely convergent.
In the lower jaw (the upper being uncertainly known in this respect)
the ‘‘Mixodectinae” retain a canine, and the enlarged tooth is an
incisor, while in the ‘‘Microsyopinae”’ there is only the enlarged tooth
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 129
anterior to P*. The enlarged teeth are thus not rigidly proved to be
the same, and with his customary caution Matthew stressed the fact
that they might not be homologous. The premolars are different in
the two groups, although I believe that the difference has been over-
emphasized. In the ‘‘Microsyopinae” P*, are less elevated and more
molariform than in the ‘“Mixodectinae.’”’ The molars are almost
identical in the two groups, except that in the earlier forms there is a
distinct and markedly internal hypocone, while in the later the
hypocone is anomalously small and is less internal.
The two genera discovered since Matthew’s work, especially
Eudaemonema, alter this situation. Hudaemonema has the anterior
(lower) dentition less specialized than in Mizodectes, and Elpidophorus
has it either closely similar to Mixodectes or slightly less reduced. In
both cases there is no reason to believe that the enlarged incisor is
not homologous with that of Mixodectes and also with that of Cyno-
dontomys. In both genera P, is submolariform. In Hudaemonema
it is very similar to that of Cynodontomys and Microsyops, rather than
to the contemporary Mizodectes. In Elpidophorus it is aberrant in
having a strong, projecting paraconid. P* is not known in Hudae-
monema; in Elpidophorus it closely resembles that of the Eocene
genera. In Hudaemonema the upper molars have strong, internal
hypocone, comparable to Mirodectes, while Elpidophorus is more
like the Eocene genera in this respect. These genera thus mingle
characters of the “Mixodectinae” and the ‘‘Microsyopinae”, and
they make it impossible to maintain a consistent separation between
these groups. At the same time they strongly support the reality of
a relationship between them.
For one reason or another the known Paleocene genera of this
family cannot be considered ancestral to each other or to the Eocene
forms. Thus Eudaemonema is the most primitive as regards the
retention of anterior teeth, but its premolars are more advanced than
in Mizodectes and Indrodon, and its strong, projecting hypocones seem
to exclude it from the ancestry of Elpidophorus or of Cynodontomys
and Microsyops. Mirxodectes and Indrodon cannot be ancestral to the
later forms for the same reason and cannot be structurally ancestral
to the contemporary Hudaemonema because of their reduced anterior
dentition. Elpidophorus has aberrant specializations in P, and in
details of molar structure that seem to exclude it from consideration
as the ancestor of the Eocene genera. Evidently four different groups,
intimately related but all on different lines of phyletic descent, are
represented. These can be contrasted, among other details, by the
characters listed in table 28.
130
BULLETIN 169, UNITED STATES NATIONAL MUSEUM
TABLE 28.—Comparison of dentition of six genera of Mixodectidae
Genus
Mizodecies and
Indrodon.
Eudaemonema--
Elpidophorus-.- -
Cynodontomys
and Microsy-
ops.
Formula
AES ER hs Se
7) I eae
1(+?).1.3.3-
1:03:37 —
Py
Elevated, paracon-
id minute, meta-
conid rudimen-
tary or absent,
talonid poorly
basined with 2
cusps.
About as tall as mo-
lars, paraconid
small, metaconid
large, talonid
well basined,
with 3 cusps.
With paraconid
large and project-
ing, otherwise
comparable to
Eudaemonema.
Comparable to Eu-
daemonema.
Internal] lower
molar cusps
Slightly or not
taller than ex-
ternal. Meta-
conid opposite
or slightly pos-
terior to proto-
conid.
About as in Mizo-
dectes.
More definitely
higher than ex-
ternal. Meta-
conid — slightly
anterior to pro-
toconid.
About as in Mizo-
dectes.
Pi
Elevated, ex-
ternal cone
simple.
(Unknown) --_--
Less elevated,
with separate
paracone and
metacone.
Comparable to
Ilpidophorus.
Upper
molars
With strong
hypocones,
projecting
internally.
About as
Mixodectes.
in
With weak hy-
pocones, not
projecting
internally.
Comparable to
Elpidopho-
Tus.
A possibility worthy of serious consideration is that the Plagio-
menidae may be related to the Mixodectidae.
ing principal characters suggestive of such a relationship:
They show the follow-
Molarization of premolars somewhat similar to mixodectids (except Mixodectes
and Indrodon).
Upper molars with feeble hypocone shelf and pronounced and peculiar median
transverse valley (asin Elpidophorus and to a less degree some other mixodectids),
and otherwise generally but more vaguely similar.
Tendency to emphasize external shelf of upper molars and to develop cuspules
on it (but see below).
Elevation of internal over external cusps of lower molars (a tendency in all
mixodectids, pronounced in Elpidophorus).
Lines joining protoconid to metaconid and hypoconid to entoconid parallel and
anterointernal-posteroexternal (tendency in mixodectids, pronounced in Elpi-
dophorus).
Paraconids, and trigonids generally, similar.
Molar talonids markedly broadened.
These, and a few minor details, produce a general type of dentition
common to plagiomenids and mixodectids and not, as far as I know,
to any other groups.”
85 This was evidently partially noticed by Matthew (1918, p. 600), for he notes the resemblance to Plagio-
mene of “an undescribed genus from the Paskapoo beds’’, which was undoubtedly Elpidophorus, not then
named and not until very recently known to be an aberrant mixodectid.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 131
On the other hand, the following characters show that the relation-
ship cannot be very close, if it exists at all:
Rather than a single mesostyle developed as a fold of the ectoloph, the plagio-
menids have two independent median cusps on the outer shelf of the upper molars.
The anterior incisors (in the lower jaw, at least) are not reduced in number and
none is markedly enlarged.
The hypoconulid does not have the characteristic mixodectid displacement
toward the entoconid.
The cheek teeth are all deeply furrowed and tend to proliferate cuspules.
The inconclusive evidence of possible relationship of the plagio-
menids to the Dermoptera has not been significantly altered since
Matthew wrote (1918). The chain of evidence thus tending to link
the mixodectids with the Dermoptera is so weak at every point as
not to merit serious consideration at present.
Genus EUDAEMONEMA Simpson
Eudaemonema Simpson, 1935d, p. 231.
Type.—Eudaemonema cuspidata Simpson.
Distribution Middle Paleocene, Fort Union, Mont.
Diagnosis.—Dental formula, 3773; Median incisor enlarged. Canine
larger than lateral incisor or P;. P;_;small, 1-rooted. P, submolari-
form, with small paraconid, large, high metaconid, and basined,
tricuspid talonid. Lower molars as in Mizodectes, but trigonids more
elevated and all six cusps sharper and more distinct. Upper molars
with prominent hypocones, projecting strongly internally.
EUDAEMONEMA CUSPIDATA Simpson
Ficures 25, 26
Eudaemonema cuspidata Stupson, 1935d, p. 231.
Type.—U.S.N.M. no. 9314, left lower jaw with C, P,-Ms, and roots
or alveoli of all other teeth. Found by Dr. J. W. Gidley.
Horizon and locality—Gidley Quarry (referred specimen from
Silberling Quarry), Fort Union, Middle Paleocene horizon, Crazy
Mountain Field, Mont.
Diagnosis.—Sole known species of genus. Dimensions in table 29.
Remarks.—Alveoli in the type and roots in another specimen (no.
9317) show clearly that there was an enlarged median incisor with a
procumbent, laterally compressed root, flanked by one much smaller
lateral incisor. The canine root is oval, implanted nearly vertically,
nearly as large as that of the median incisor, and much larger than
that of either of the adjacent teeth. The crown is low, with a simple,
spatulate, recurved tip. P, is not known, but its alveolus in three
different specimens suggests that it was constantly present, although
absent in all other known members of this family. Its root is single,
small, and circular in section.
132 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
P, has a single but larger root. Its crown is simple, with one cusp,
convex on the outer face and excavated anterointernally near the tip,
followed by a small, mainly internal heel, not forming a definite cusp.
P; is larger and has two poorly separated roots. The anterointernal
excavation is accentuated and tends to pinch off a very rudimentary
paraconid, but there is no trace of a metaconid. The heel rises to a
single, distinct cusp. P, is nearly molariform. The paraconid is
small but distinct and is median. The metaconid is nearly as high
as the protoconid, with which it is partly confluent. The talonid is
well developed, of about the same width as the trigonid, and has a
large hypoconid and smaller entoconid and hypoconulid, the latter
median.
>
sD
Z
A
\)
en
FIGURE 26.—Eudaemonema cus-
pidata Simpson, U.S.N.M. no.
FIGURE 25.—Eudaemonema cuspidata Simpson, U.S.N.M. no. 9314, 9558, left upper molars: a, Ex-
left lower jaw: a, Crown view; 6, internal view. Three times natu- ternal view; 6, crown view.
ral size. Three times natural size.
M,-» are closely similar to each other. The trigonid is moderately
elevated and is narrower than the talonid. The paraconid is low and
shelflike but is distinct and is united by a crest to the crescentic pro-
toconid. The paraconid is about intermediate between the median
and internal positions. The metaconid is slightly higher than the
hypoconid, and the hypoconulid is lower and near the entoconid but
more distinct from it than in Hlpidophorus. All three talonid cusps
are unusually lofty and distinct. A cuspule tends to develop on the
hypoconid-metaconid ridge. Ms; has the talonid narrower, about as
wide as the trigonid, and the hypoconulid projects posteriorly and is
higher than the other talonid cusps.
Of the four specimens that show the posterior mental foramen, it is
beneath P, in two (including the type), is double with both under P,
in another, and in the fourth is beneath P, but is followed by another
of much smaller size under M,. In all cases the anterior mental
foramen is larger, pronounced, and beneath P,.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 133
U.S.N.M. no. 9558, from the Gidley Quarry, is a left upper jaw
with M!3. It closely resembles Mixodectes, occludes well with some
of the lower jaws of Hudaemonema cuspidata, and is not what would be
expected in the upper jaw of any other known species, so that I place
it here with some confidence. Aside from details of proportion, as
shown in the figures, the outstanding differences from Mizodectes are
the better development of the conules, especially the metaconule
(almost lacking in Mizodectes), and the even greater internal displace-
ment of the hypocone of M?’.
TABLE 29.— Measurements (in mm) of lower teeth of Eudaemonema cuspidata
P2 P3 P4 Mi M2 M3
U.S.N.M. no. | ee | ee) Se a ae
L WwW L WwW L WwW L WwW L Ww L WwW
EK: eS a ee Oe 1.8 3 2.0 1.4 Perl 1.9 3.3 257 OEE: ag 4.0 2.6
(BY as he a ee el ee ae 2.6 TOS 525 [bee 3:5 Ai
OS eee ee eae S ene ee SE See 1.9 155 2.9 2.0 By E 2.6 3.6 2.8
SHI to Pe 5 Se oe er eae | (eee | oy (Bee Se | ee) ae eee ee eee 3.8 2.9
Bul} Se See eee Le eee 1.9 1.6 PIT PP) 3.0 prc! 3.4 2.9
YB SV ee ee el [mete pel ee Ee eee | [ns Pari 1.9 3.2 7 af 355 2.9
Genus ELPIDOPHORUS Simpson, 1927
ELPIDOPHORUS MINOR, new species
FiGureE 27
Type.—Princeton no. 14201, left lower jaw with P;-M». Collected
by A. C. Silberling.
Horizon and locality—Probably Silberling Quarry, Fort Union,
Middle Paleocene horizon, Crazy Mountain Field, Mont.
Diagnosis —Smaller than EF. elegans or E. patratus. P? slenderer
than in E. patratus, paraconids P,-M, more strictly internal, heel of P,
smaller and less strongly basined, elevation of inner cusps P,-M,
distinct but slightly less pronounced than in EF. patratus.
Remarks.—The type and only known specimen was found by Silber-
ling on January 18, 1903, and is labeled as from the Torrejon, Locality
No. 2 (not of the serial list later started and employed in this work).
Mr. Silberling states that these data mean the No. 2 beds at or near
the Silberling Quarry. It is extraordinary that no further material of
this peculiar form seems to occur in the much larger collections made
subsequently.
The species is very distinct from the later E. patratus of this field,
and it will probably prove to be generically different, but they are
certainly allied and the present data do not seem to warrant generic
definition. EH. minor resembles Eudaemonema more than does £.
134 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
patratus, but it is closer to the latter than to E. cuspidata and shows the
Elpidophorus line to have been distinct at this time.
Dimensions of the type are as follows: Length P3, 2.0; width Ps, 1.4;
length P,, 2.7; width P,, 1.9; length My, 2.8; width M,, 2.6; length
M,, 3.0; width Mg, 2.8.
INN
2
te
FIGURE 27.—Elpidophorus minor, new species, Princeton Univ. no. 14201, left lower jaw: a, Crown view; 6,
internal view. Six times natural size.
?INSECTIVORA, incertae sedis
PICRODONTIDAE, new family
Type.—Picrodus Douglass, 1908.
Distribution.—Middle and Upper Paleocene, North America.
Diagnosis—Minute insectivorelike or batlike forms of doubtful
ordinal affinities, with one pair of greatly enlarged incisors (at least
in lower jaw), muzzle long and slender, canines reduced, premolars
small with no tendency to molarization, molars large, brachyodont,
with shallow, expanded basins and indistinct cusp structure, adaptively
resembling molars of the recent Phyllostomatidae.
Discussion.—At present only two genera, Picrodus and Zanycteris,
are referred to this family, and these are not directly comparable with
each other. The evidence for their close relationship is, however,
impelling, as discussed below. The separation of family characters
from those merely generic is not entirely practicable in this stage of
knowledge, but there can be little doubt that these two genera do
belong to a family otherwise unknown, and the characters given in
the above diagnosis distinguish them from any other family. The
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 135
molars invite comparison with the Phyllostomatidae, although they
do not prove that a real relationship exists. The character of the
antemolar dentition distinguishes the Picrodontidae sharply not only
from the Phyllostomatidae but also from all other Chiroptera.
The affinities of the Picrodontidae are wholly dubious at present.
They compare in a very broad and general way with the Insectivora,
Chiroptera, and Primates. Reference to the Primates is merely a
possibility, with no positive evidence to commend it. Evidence for
reference to the Chiroptera is seen in the phyllostomatidlike molars
but is really very tenuous and does not at present warrant the extraordi-
nary conclusion that the Chiroptera had already in the Middle Paleo-
cene achieved this peculiar and aberrant molar pattern and at the
same time had lost, or not yet acquired, characters otherwise universal
among chiropterans. Such references, even when circumspectly
expressed, are moreover likely to be misleading, for they inevitably
are restated in more general works by authors not acquainted with the
original material, in some such form as “Specialized phyllostomatid
bats were already present in North America in the Middle Paleocene”,
without the necessary addition that the evidence actually falls far
short of proof. It is more conservative and less prejudicial to future
work to refer the Picrodontidae to the ?Insectivora, using Insectivora
in its scrap-basket sense, pending discovery of more conclusive indica-
tions of affinity. When these are discovered, they are (as far as can
be foreseen) as likely to point to the Insectivora as to any other order,
Genus PICRODUS Douglass, 1908
Picrodus Douatuass, 1908, p. 17.
Megopterna Dovaeuass, 1908, p. 18.
Type.—Picrodus silberling: Douglass.
Type of Megopterna.—Megopterna minutia Douglass.
Distribution.—Middle Paleocene, Fort Union, Montana.
Diagnosis —Enlarged, procumbent anterior lower tooth, followed by
three or four small teeth, the most posterior (Ps?) 2-rooted but small
and simple. My, much enlarged, with a small, elevated, and procum-
bent trigonid with three poorly differentiated cusps, heel elongate and
large, with a curving crest and two vague internal cuspules, basin not
closed. M, with lower, subquadrate but 3-cusped trigonid, large, oval,
basined talonid with crest and two internal cusps. Enamel of both
talonids papillated.
Remarks —From Douglass’ specimens and, still more, his some-
what diagrammatic figures 1t would appear altogether impossible that
Picrodus and Megopterna should be synonymous, but this is shown to
be true beyond any question by the larger series of specimens now
available. The type of Picrodus included P, and M,, the latter im-
perfect, and that of Megopterna included M, and a small fragment of
1192123710
136 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
M, that Douglass mistook for a complete tooth. The type species
are synonymous.
Douglass referred Picrodus questionably to the Epanorthidae
(=Caenolestidae) and Megopterna questionably to the Insectivora,
without family reference. The resemblance to caenolestids is con-
fined to a vague adaptive similarity to some fossil forms with enlarged
M, and is not indicative of affinity. Picrodus is almost certainly a
placental mammal. Among placentals, however, I am not acquainted
with any genus with which close and direct comparison is possible.
There is, indeed, a vague resemblance to certain highly specialized
recent bats, but this does not extend to structural details, is contra-
dicted by the quite different arrangement of the anterior dentition,
and is more likely to be misleading than not.
There is one known genus, Zanycteris, with which Picrodus is almost
certainly closely related, although direct comparison is impossible
since in Picrodus only lower and in Zanycteris only upper teeth are
known. As I have elsewhere noted (Simpson, 1935a), Zanycteris
(like Picrodus) resembles some recent bats, particularly the phyllo-
stomatids, in adaptive characters of the cheek teeth but is different
in details probably of more importance as indices of affinity and in
the structure of the anterior dentition, as far as it is known. The
great probability of affinity between Picrodus and Zanycteris is inde-
pendent of the possibility that they are related to the Chiroptera.
In Zanycteris the reduction and complete lack of molarization of the
premolars, the enlargement of M' and reduction of M?, and the peculiar
papillated coronal enamel are all unusual specializations analogously
developed in the lower dentition of Picrodus. Furthermore, even in
detail the shapes of M'!~? in Zanycteris adapt them perfectly for occlu-
sion with lower teeth like those of Picrodus. Zanycteris paleocena
will not occlude with Picrodus silberlingi, being a smaller species, but
probably a dentition structurally the same as that of Zanycteris but of
different size would occlude with Picrodus silberlingt. Zanycteris is
known only from one specimen found in the Tiffany, Upper Paleocene,
of southwestern Colorado. Its type is certainly not the same species
as that of Picrodus, and the genera are probably distinct, but not
surely. Knowledge of their exact affinities must await discovery of
upper teeth of Picrodus or lower teeth of Zanycteris.
PICRODUS SILBERLINGI Douglass
Figure 28
Picrodus silberlingi Doucuass, 1908, p. 17.
Megopterna minuta Douatass, 1908, p. 18.
Type.—Carnegie Mus. no. 1670, right lower jaw with P,-M,.
Collected by A. C. Silberling.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 137
Type of Megopterna minuta.—Carnegie Mus. no. 1675, left lower
jaw with M, and part of talonid of M;. Collected by A. C. Silberling.
Horizon and locality —Types from Silberling Quarry, most referred
specimens from Gidley Quarry, Fort Union, Middle Paleocene horizon,
Crazy Mountain Field, Mont.
Diagnosis.—Sole known species of genus. Dimensions given below.
Remarks.—From alveoli it is clear that this species had a much
enlarged, procumbent anterior tooth, probably an incisor, with a
compressed root. U.S.N.M. no. 9866 includes M, of P. silberlingi
and also a loose tooth, which probably is an associated lower incisor.
It has a completely enameled crown, curving sharply to a point. The
whole crown has a series of eight or nine ridges or angulations, diverg-
ing posteriorly from the apex, so that in transverse section it is
irregularly polygonal. Aside from these, one side is more convex, the
other somewhat excavated, with a slight basal cingulum.
Pp GE: a
LES G Z ek f
YZ FE el y
(I \ SEZ
FIGURE 28.—Picrodus silberlingi Douglass, U.S.N.M. no. 9622, right lower jaw: a, Crown view; 6, external
view. Four times natural size.
The anterior tooth is followed by three small, closely spaced, ap-
proximately equal alveoli. The material does not indicate whether
these were for three separate teeth or for one 1-rooted tooth and
one 2-rooted. The next tooth, presumably P,, has two roots in the
several specimens that show it, not one as stated by Douglass for the
type. It has a simple main cusp, more procumbent than shown in
Douglass’ figure, followed by a small heel. The next tooth, pre-
sumably M,, is the largest in the jaw and is very peculiar. It differs
considerably from Douglass’ figure, although I believe that the pres-
ent specimens do belong to his species and that the discrepancy is
due to the worn and broken nature of his specimen and the impos-
sibility of accurate observation except under a binocular microscope
at magnifications of 15 or 20 X. This tooth consists of a trigonid and
talonid, but both are greatly modified. The trigonid is small and is
produced and procumbent, as if drawn forward and upward in a
plastic condition. The protoconid lies near the midline of the tooth
as a whole. The metaconid is slightly lower, poorly separated from
the protoconid, and internal and slightly posterior to the latter. The
138 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
still lower and likewise poorly separated paraconid is almost directly
anterior to the protoconid but slightly more internal. The talonid is
wider than the trigonid and is very long. It has a crest that begins
rather indefinitely on the external side against the base of the trigonid
and curves back to the posterointernal corner of the tooth. Its
highest part is where it swings internally and across the midline of
the tooth, and here it bears two or three vague cuspules. There are
also two small cuspules on the inner margin of the talonid, separate
from the crest and at a lower level. The more definite of these is
just anterior to the posterointernal corner, and the other vague cusp
lies between this and the metaconid base. The sloping and volute
surface of the talonid, from the crest down to the inner margin, Is.
finely papillated and wrinkled. The lowest point of this surface is.
at the posterointernal corner, where there is an almost spoutlike exit.
from the vague talonid basin.
Mz was figured by Douglass (“‘Megopterna minuta’’), but his draw-
ing makes the cusps appear more upright, sharp, and distinct than
they really are. The trigonid suggests that of M; but is much less.
elevated, the cusps are better separated, the paraconid is more inter-
nal, and the trigonid is given a more quadrate form by the angulation
of the crest connecting protoconid and paraconid. The talonid is
broad and oval, less sloping and more distinctly basined than that of
M,. The crest defines the posteroexternal angle, instead of curving
obliquely across the tooth as on M,, and there are two distinct inter-
nal cusps, the more posterior of which is connected to the crest. The
basin surface is papillated as on M,.
M; is not preserved on any specimen in the collection. From its
alveoli, it was smaller than M,. Upper teeth have not been recog-
nized.
From the downward curvature of the lower margin posterior to the
dental region, it is evident that the angie was of placental type. The
mental foramina are numerous and variable. There may be a cluster
of three or four in the general region of Py. The most constant
appear to be a fairly large foramen approximately between P; and P,
and a smaller one about between P,; and M,.
The type is not well preserved, and I have not remeasured it. It
may be slightly larger than the other specimens, but there is no doubt
that all are conspecific. The most reliably measurable dimension is
the oblique maximum diameter of My, that is, a dimension in the
midline in a vertical (but not also a horizontal) plane, from paraconid
to base of posterior end of talonid.*® The constants of this dimen-
sion in the National Museum sample are: N, 8; R, 2.6-2.9; M,
2.7140.04; o, 0.105+0.026; V, 3.9+1.0. The width of this tooth
86 The ordinary length, a horizontal between transverse, vertical tangential planes, would show great
subjective and accidental variation in such a small and peculiarly oblique tooth.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 139
is not so accurately measurable but is recorded within the range 1.0
to 1.3, mean 1.16, for these eight specimens. P,, poorly preserved
and very difficult to measure, has a maximum oblique diameter of
about 1 mm and a width of 0.6 or 0.7 mm. M4, is well preserved only
in the type of Megopterna minuta, where it is 1.4 mm in length and
about 1 mm in width. The less completely preserved specimens of
this tooth do not suggest a deviation of more than 0.1 mm from this.
The one Silberling Quarry specimen in the National Museum col-
lection has M, with the dimensions 2.8 and 1.1, well within the range
of the Gidley Quarry material.
Family Uncertain
Genus and species undetermined
Figure 29
U.S.N.M. no. 9777, from the Gidley Quarry, is a right humerus
of a fossorial mammal of about the size of a recent Scalops. It is
imperfect but preserves highly characteristic features. ‘The laterally
compressed head, short, stout, twisted shaft, and flattened, widely
flaring distal end are disposed in such a way that if the head was
directed posteriorly, the entepicondyle was anterior and only very
slightly internal in position, and the ectepicondyle similarly posterior,
so that the lower arm was thrown outwards almost at right angles
to the body. The bicipital groove, mainly occupying the proximo-
internal quarter of the posterior face, is deep and narrow, bounded
by sharp crests and elevated tuberosities, which are, however, broken
off. The pectoralis major insertion is broad and shallow, occupying
most of the proximal half of the anterior face of the shaft, and not
sharply bounded distally. The deltoid process is broken, but from
its base it was more prominent and more internal than in Scalops,
more proximal and heavier than in Arctoryctes. The notch between
head and ectepicondyle is nearly semicircular. The distal end has
greatly produced epicondyles, the extension of the ectepicondyle far
beyond the globular capitulum being especially striking, in comparison
with Scalops. The other distal articulations are poorly differentiated
or preserved. The entepicondylar foramen is strangely developed as
a long, small canal, running from the posterior face near the internal
margin to the middle of the anterior face of the broad distal end.
This peculiar humerus resembles those of recent moles in many
respects but also differs throughout in detail. Unquestionably the
resemblance bespeaks similarity of habits. Whether it also indicates
phylogenetic affinity is quite uncertain. In some respects resemblance
is closer to Arctoryctes from the Oligocene (see Schlaikjer, 1933), but
there are also numerous differences: The distal end is more nearly
parallel to the long (anteroposterior) axis of the head; the deltoid
140 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
process is less internal, stouter, and more proximal; the ectepicondyle
is more produced; the entepicondylar foramen, or rather canal, is
longer; and other differences of proportion and detail are seen. Never-
theless a relationship seems probable. The Arctoryctes humerus was
supposed by Matthew to belong to a chrysochlorid, but Schlaikjer
has shown that the evidence is all against this view and favors talpid
affinities. Arctoryctes may belong with the dentitions and skulls.
known as Proscalops.
FIGURE 29.—Humerus of an unidentified fossorial mammal: a, Anteroexternal face; b, posterointernal face.
Four times natural size.
On the basis of the teeth, no genus known from the Gidley Quarry
would seem to be closely allied to Proscalops. Some nyctitherids
have been supposed to be talpids or at least talpoids, but the only
probable nyctitheriid in this fauna, Stilpnodon simplicidens, is too
small to have had this humerus. The humerus does not belong to a
multituberculate nor to any other order known in this fauna save the
Insectivora. It is not leptictid and cannot belong to Aphronorus if
that genus is really a pantolestid, but might if the genus does not
belong with Palaeosinopa and Pantolestes. It might belong to Gela-
stops but probably does not if that genus is correctly considered an
ally of Didelphodus. Eudaemonema shows some, but only very
distant, resemblance to such dentitions as Proscalops and might
conceivably have had a fossorial humerus. The dentition of the
animal represented by this humerus may be unknown, although this
is improbable in view of the many jaws and few humeri collected
from the quarry.
In any event the presence of such a specialized fossorial animal in
this ancient fauna is of great interest.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 141
Order PRIMATES Linnaeus, 1758
The Fort Union primates are of exceptional interest as the oldest
known members of the order to which man belongs, and any light
that they can cast on the early history of this great group is highly
important. Dr. Gidley fully recognized these facts, and when the
arduous task of preparation was finally completed, he turned first to
the primates in beginning his definitive work. His previous papers
were all preliminary and provisional, but he completed the primate
section of his proposed memoir and published it in 1923 as a separate
paper, later to be united with the other proposed sections into a
single monograph. No other section was ever finished, and the pri-
mate paper was Gidley’s last contribution to the Paleocene.*’
When these primates were discovered they were far the oldest
known. Many primates were known from the Eocene of Europe
and North America, but only one, Plesiadapis, was known from the
Paleocene, and this was considered as only very doubtfully primate
and is considerably younger than the Fort Union primates of Gidley’s
collection. After Gidley’s discovery, but before its publication,
Matthew (1915) added Nothodectes (=Plesiadapis) also from the
Paleocene, and in 1921 Matthew and Granger added several more
genera from the Tiffany, but these are all younger than Gidley’s
material. Jepsen and I have made recent additions to the known
upper Paleocene primates, but only Plesiolestes Jepsen, 1930, is of an
age comparable to Gidley’s genera, and there is no reason to suppose
that it is older.®
It is in accord with Gidley’s intention that these forms are here
redescribed in connection with the whole fauna, despite their publica-
tion previously. This is the more necessary because since Gidley’s
publication knowledge of early primates has been greatly increased
both by discovery and by revision, calling for reconsideration of many
points that he mentioned. For this reason, his diagnoses and discus-
sions are not quoted in full, but are revised in the light of the wider
knowledge of today and of the somewhat different conclusions to
which this has led me.
Gidley recognized four new genera in this fauna and placed six
species in them. The fact that two species are based on upper jaws,
with lowers referred, and the other four on lower jaws, with uppers
referred to three of them, introduces a slight element of doubt, but on
the basis of the lower jaws, at least, it is certain that six species are
represented and that Gidley’s identifications of all these specimens are
"With the minor exception of a very brief note on the Tiffany.
58 Abel (1931) lists Plesiolestes as from the Lower Paleocene and suggests that it is the oldest known
primate, but it is from the middle Paleocene and not appreciably, or not at all, older than the genera here
discussed, one of which it closely resembles.
142 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
correct. The only taxonomic change to be introduced is that a fifth
genus is made to receive a species that Gidley placed doubtfully in
Palaechthon.
Family 7ANAPTOMORPHIDAE Cope, i883
In this fauna the three genera Paromomys, Palaechthon, and
Palenochtha are very tentatively listed with the Anaptomorphidae,
although (as will appear) the relationship is not clear and this whole
complex of early primates is highly polyphyletic and very confusing.
Paromomys, Palaechthon, and Palenochiha evidently belong to
slightly divergent lines, but they have certain characters in common.
The most important of these are:
1. An enlarged, semiprocumbent lower incisor, its root not extending beneath P,.
. Other lower incisors vestigial and variable or absent.
. Lower canine present and only slightly reduced.
P, and probably sometimes P, absent.*?
. Py little or not enlarged, trigonid simple, elevated, with low, 2-cusped talonid.
. Molar trigonids with small, generally short and quadrate basins, paraconids
meneralle: distinct but reduced, cusps marginal or nearly so.
7. Heels of M,-» large, simple, broadly basined.
8. M; with third lobe, which, however, differs greatly and characteristically in
the three genera.
9. P3 (as far as known) 2-rooted and not transverse.
10. P4 transverse, strong protocone, paracone and metacone little or not differ-
entiated, conule feeble or absent.
11. Upper molars without mesostyle, protostyle, or hypocone; two small but
distinct conules; posterointernal corner of crown expanded and basined to varying
degrees; inner face of molar with vertical groove at least on M?.
Oop wry
These suggest a possible fairly immediate common origin for the
three genera, but they are diverging from each other, principally as
follows:
Paromomys: Antemolar dentition of unmodified basic type as listed above.
Molar trigonids very short and quadrate, paraconid almost disappearing by fusion
with metaconid on M23. Third lobe of M3 very strong, with at least two distinct
cusps. Inner base of M?, at least, more or less bilobed. Posterointernal expan-
sion of upper molars very marked.
Palaechthon: Ps more progressive, with distinct paraconid and metaconid.
Molar trigonids less quadrate and paraconids more distinct. Third lobe of Ms;
weaker but still with two cusps. Upper molars not bilobed, posterointernal expan-
sion less.
Palenochtha: Anterior dentition further modified by loss of another tooth, prob-
ably P,. Py much asin Paromomys. M3; with weak, l-cusped third lobe. Upper
molars not bilobed, posterointernal expansion slight.
Except for the absence of P, (which, however, is not absolutely cer-
tain), Palenochtha seems definitely the most primitive of the three and
its general structure is such as might be expected in the ancestry of
59 Certain homologies, discussed om a later page, are here assumed. Exact identification is impossible, but
as the teeth are probably homologous between the genera in question, if they are labeled consistently it does
not matte from the point of view of determining affinities whether the labels prove to be correct or not,
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 143
both the other genera. Paromomys and Palaechthon show crossing
specializations. The general molar structure of Palaechthon is
specialized more or less in the direction of Paromomys but is less aber-
rant, while its P, is definitely more progressive. Paromomys shows
distinctly the most aberrant molar structure but has P, still relatively
unproeressive.
The only known primate of comparable age is Plesiolestes Jepsen,
from a Torrejon equivalent in the Fort Union of northern Wyoming.
Its age is not appreciably different from that of the Gidley Quarry spec-
imens, and the geographic locality is not very distant, all occurring in
the same widespread formation. Jepsen tentatively referred his
genus to the Plesiadapidae but noted (1930a, p. 506) that “there are
many structures on the two specimens which are not like those of other
Plesiadapids.”” He did not compare with Gidley’s previously pub-
lished genera, which Plesiolestes resembles in many ways. The
anterior alveoli show an enlarged semiprocumbent incisor and a
smaller, less procumbent canine, as in all three of Gidley’s genera
here discussed, and also a moderate P,, as in Paromomys and Palaech-
thon. Ps is also closely similar, but relatively larger, being about as
high as P,, whereas in Gidley’s genera it is lower. P, closely resembles
that of Palaechthon, the only difference clear from the available data
being that in Plesiolestes the heel is wider and the paraconid and meta-
conid stronger, especially the latter. The molars are very similar to
those of Palaechthon and seem to me to show no difference of probably
generic value.
While Plesiolestes may be provisionally accepted as valid, chiefly on
the basis of the more progressive P,, it is almost surely very closely
related to Palaechthon, and the distinction of the genera is not at pres-
ent wholly satisfactory. If, as is possible, Plesiolestes is somewhat
younger, it could well be a slightly modified and progressive descend-
ant of Palaechthon. Its diagnostic features, as against Palaechthon,
seem to me modifications away from as much as toward the plesiada-
pids. In any case it is surely closer to Palaechthon than is either genus
to any undoubted plesiadapid, and if a plesiadapid relationship exists
at all, Palaechthon is probably less removed from that line than is
Plesiolestes.
Palenochtha, the least aberrant of the present genera as regards
comparison with an abstract protoprimate dentition, seems to resemble
the Eocene tarsioids (in the broadest sense) more than any other
known mammals. The specialization of the anterior lower teeth is
not exactly as in any later tarsioid but is within the apparent poten-
tialities of the group. Omomys, from the Bridger, has two enlarged
60 The American lower Eocene species placed in Omomys are very doubtfully congeneric with the Bridger
genotype. As noted by Teilhard, the European lower Eocene specimens are very distinctive and might
be, in my opinion definitely are, representative of a different genus but one close to and perhaps structurally
ancestral to true Omomys.
144 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
anterior teeth followed by three premolars, but in it there is a small
tooth between these two enlarged teeth, which is either much more
reduced or wholly absent in the much older Fort Union genera.
Absarokius may very closely resemble the Fort Union genera in the
anterior teeth, although this is very dubious, as they are known in
Absarokius only from poorly preserved alveoli of one specimen, which
seems to show less disparity between the incisor and the ?canine.
Tetonius and the European Necrolemur have a single enlarged anterior
tooth,® a condition that could be derived from that of the middle
Paleocene genera, although there is no adequate evidence that it was
so derived.
P, is more primitive in Palenochtha than in any later tarsioid genus
known to me, but the difference in such forms as Anaptomorphus or
“Omomys”’ belgicus is not marked, and as the increasing and diverg-
ing specialization is in keeping with the relative ages it has no crucial
bearing on general affinities. The lower molars of Palenochtha are
much like those of ?Omomys vespertinus, “Omomys”’ belgicus, and simi-
lar forms, that is, those Eocene tarsioids in which the molars are least
specialized. The same may be said of the upper molars: those of
Palenochtha show distinctions by which the genus may be recognized
(such as the internal groove and more inclined protocone), but they
very closely resemble the least aberrant Eocene tarsioids. Compari-
son with ?Omomys vespertinus is especially suggestive of affinity. Most
later genera differ in the manifestly progressive development of sec-
ondary internal cusps.
It is, incidentally, worthy of note that Palenochtha has no known
character that would exclude it from ancestry to TYarsius, itself,
although of course the absence of intermediate stages makes this ob-
servation unworthy of being advanced except as an interesting but
wholly untested possibility.
The more advanced P, of Palaechthon does not call for detailed con-
sideration. It is in line with progressive changes in many tarsioids
and some other primates, although it shouid be noted that the devel-
opment of P,in the Tetonius, Carpolestes, Apatemys, Plesiadapis, and
some other groups lies along distinctly different lines.
The peculiar molar structure suggested in Palaechthon and fully
developed in Paromomys is more distinctive. The short quadrate
trigonid and marginal paraconid approximated to the metaconid
appear among tarsioids in only one or two later genera. Absarokius
has very similar trigonids on M,3, but that of M, is more elongate,
probably secondarily in connection with the shearing development of
P,. Other American tarsioids are more distinctive. Among Kuropean
forms, only Necrolemur and Microchoerus are similar, and they are
61 Commonly called the canine, but it seems to me more probable that it is an incisor in both cases.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 145
smore advanced in the reduction of the paraconid, but are much
younger. The broad third lobe of M; and double hypoconulid also
-appear in Necrolemur and Microchoerus, but not in Absarokius. Among
American tarsioids only Washakius has a similar talonid on M3, and
its trigonids are quite different.
The characteristic posterointernal upper molar expansion and basin-
ing of Paromomys are suggested in many later tarsioids, such as
Absarokius, Hemiacodon, Shoshonius, Tetonius, and, in Europe, Nanno-
pithex (most marked in Absarokius and Nannopithex), but in all these
the structure is much less marked. In some cases (e. g., Tetonius) it
is so slight that it is noted only by special search with Paromomys in
mind, and in all the instances mentioned there is the characteristic
distinction that a posterior cingulum passes internally beyond the
jimits of the incipient (or vestigial) basin and tends to form a hypocone
at its inner end. This could be a specialization from the Paromomys
condition, but the difference is clear and there is no evidence of cer-
tainly intermediate stages. In the European Necrolemur (and its
highly modified ally, Microchoerus), however, the hypocone is on the
rim of a basin much like that of Paromomys, and structural ancestry
as regards this character is quite possible but hypothetical.
In summary comparison with the acknowledged tarsioids, there are
resemblances throughout and every separate structure of the Fort
Union genera is approached in some later genus. The fundamental
‘similarity is most clear in Palenochtha, but even in this most general-
ized type the anterior dentition is too specialized for ancestral rela-
tionship to any known later genera but Tetonius, Necrolemur, Micro-
choerus, and (still more doubtfully) Absarokius, and in these cases the
minor morphological differences are also marked and annectant forms
unknown. Paromomys and Palaechthon also resemble various later
genera, but in most cases crossing specializations make any approach
to direct phyletic connection impossible. Absarokius is, on the whole,
the most similar American form, but in several respects it is apparently
less specialized; for instance, in the simpler heel of M;, probably less
enlarged incisor, and smaller protocone of P* (which may, however, be
secondary), despite its younger age.
The European genus Necrolemur ® compares more closely with
Paromomys than does any known tarsioid to the extent that it exhibits
all the principal specialized characters of Paromomys and that while
it has numerous additional specialization of its own, no crossing special-
zation is involved. Its dental formula is probably 7{35. Stehlin
(1916) has placed this upper formula beyond any serious question.
He gives the lower formula as 5;q3, but the evidence is very uncon-
vineing. A priori it is highly improbable that an enlarged median
62 The following remarks apply equally to Microchoerus, except that the latter is much more highly special-
ized in the dentition. If Necrolemur comes from Paromomys, then, ipso facto, Microchoerus does also but
has eyolved more rapidly.
146 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
tooth should be a canine, that P, should be present in an upper Eocene
tarsioid when it is absent, as far as surely known, in every other known
tarsioid even in the Paleocene, or that an enlarged lower canine should
occlude against an enlarged first upper incisor and anterior to a second
upper incisor. The occlusion in itself is so suggestive of an incisor
that only the strongest contrary evidence would warrant any other
conclusion, and the other considerations seem to place this almost
beyond doubt. It is true that in Tarsius the largest anterior mandi-
bular tooth is the canine, but as Stehlin (1916) himself has shown the
analogy with Necrolemur is very distant, and in Tarsius the lower
canine occludes between I? and C as would be expected, not between
I' and I*?. Furthermore, the actual formula in Tarsius is 33, as
I believe it was also in Necrolemur.®
If this formula be accepted for Necrolemur, its anterior dentition
could be derived from that of Paromomys by further enlargement of
the already enlarged incisor and great reduction of the canine, still of
moderate size but not enlarged in Paromomys. The premolars of
Necrolemur are broader, lower, and more proclivous than in Paro-
momys, and there is a distinct metaconid on Py. The lower molar
structure is closely similar throughout except for details in Necrolemur
like the complete loss of separate paraconid on M,.3, which are the
logical continuation of tendencies clearly present in Paromomys.
In the upper jaw, the 3-rooted P® of Necrolemur is also progressive.
P* and the molars are less transverse than in Paromomys, a feature of
no clear significance. The protocone of P* may be smaller in the
later genus; if so, it is the only character that suggests, and it does
not prove, that Necrolemur could not be derived from Paromomys.
Aside from their proportions, the upper molars of Necrolemur differ
in having stronger conules (the metaconule double) and distinct
hypocones, but the basic plan is remarkably similar, as already
suggested.
As far as the dentition goes, it must be concluded that Necrolemur
and Paromomys are probably rather closely related, and the latter
could be ancestral to the former. The conclusion is obviously un-
proved and open to doubt. Corresponding with their great separation
in space and in time, the genera do differ markedly and annectant
types are unknown, but the fundamental similarity is striking.
Trogolemur, Uintalestes, and Phenacolemur are all ineertae sedis,
but all show some special resemblances to Paromomys and its Fort
Union allies. Trogolemur has the same dental formula as Paromomys,
tia3- The incisor is relatively larger, and the next tooth, presum-
ably the canine, is very small. The premolars are more expanded
63 Although the case is less clear, by analogy it seems probable that the enlarged median mandibular
teeth of Tetonius are also a pair of incisors, not canines as generally supposed following Matthew. Ishould
write the Tetonius formula either 1.0.3.3 or 1.1.2.3, of which the second is perhaps slightly more probable.
(Matthew wrote 0.1.2.3 but this is an evident lapsus, and he clearly meant to write 0.1.3.3-)
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 147
transversely but otherwise similar. P, has a metaconid. My,» are
much like Paromomys. The third lobe on M; is narrower than in
P. maturus but closely approached in P. depressidens. The cheek
teeth throughout are very close to Palaechthon but lower, broader,
and heavier. Palaechthon is an admirable structural ancestor for
Trogolemur, although the time gap is too great for definite decision.
Uintalestes is very poorly known but is evidently related to Tro-
golemur from which it differs essentially only in the further dental
reduction, having only seven teeth in the lower jaw, and the narrower
heel of P,.
The lower molars of Phenacolemur could readily be derived from
the Paromomys type but are heavier and more quadrate. P, is also
similar but is much enlarged and likewise heavier and more quadrate.
The much heavier incisor and the complete loss of all teeth between
it and P, sharply distinguish Phenacolemur, however, and the time
gap is far too short for derivation from Paromomys. The molar
resemblance may, therefore, be misleading. P* has a much stronger
posteroexternal cusp than in Paromomys, and the internal groove is
absent on the upper molars, but they have an equally and similarly
expanded posterointernal basin and in general are as close to those of
Paromomys as are the lower molars.
Resemblances to the Carpolestes and the Plesiadapis phyla are dis-
cussed in dealing with the contemporary members of the latter,
Elphidotarsius and Pronothodectes, but the adaptively related group
Apatemyidae has no known representative before the upper Paleocene.
They may, however, be summarily dismissed as possible close relatives
of the Fort Union forms, as none of their peculiar distinctions are
foreshadowed in the latter. The apatemyids, as redefined by Jepsen
(1934), have an enlarged incisor, larger than in Carpolestes or Plesia-
dapis, which more nearly resemble Paromomys and its allies in this
respect, and early lose all teeth between this and P3, at least two of
which are retained in Paromomys and in the other two groups men-
tioned. P; becomes 1-rooted and peculiarly bladed. P, is markedly
reduced even in the upper Paleocene and becomes vestigial in later
forms. The molars have a quadrate trigonid, as in many early
primates, but, especially on M,, it is much more elongate anteropos-
teriorly than in Paromomys and its allies. The upper teeth are
equally divergent.
Gidley (1923, pp. 3-4, 8-9) noted the resemblance of Paromomys and
Palaechthon to the Notharctinae in the lengthened heel of M3, the
trigonids consisting chiefly of protoconid and metaconid connected
by a loph and with an anterior shelf, and the posterointernal expan-
sion and basining of the upper molars. He added, however, that
these are not exclusively notharctine characters and concluded that
they did not indicate close affinity in this case. The resemblance is,
148 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
indeed, very close, and as far as the posterior teeth are concerned the
differences involve only a few minor details of apparent generic or
lesser value. The anterior teeth, however, are very different and are
much more specialized in the earlier genus. Pelycodus has the formula.
siag aS against yy, In Paromomys and Palaechthon, its incisors
are small and its canine large. Furthermore, the Paromomys-like
molar characters of Pelycodus are not seen in Adapis, but the Notharc-
tinae, to which Pelycodus belongs, and the Adapinae show a funda-
mental resemblance in skull and skeletal structure, which leads
(Gregory, 1920, and elsewhere) to their association in one family.
And this general structure is very unlike that of the supposedly
tarsioid genera, such as Jetonvus or Necrolemur, with which there is.
equal or greater reason for supposing Paromomys to be related.
To propose as a tentative solution of this extraordinarily intricate
problem that Paromomys is a derivative of a tarsioid-notharctine
ancestry is not fully satisfactory, for a corollary would be that the
Notharctinae were descended from a different tarsioid or prototarsioid.
ancestry from the Adapinae, one with more Paromomys-like molars.
and this is wholly unsatisfactory on the basis of the mutual relations
of Notharctinae and Adapinae as inferred from their own much
better known structures. It is much more probable either that the
marked resemblance in the molars of Paromomys and Pelycodus is
wholly convergent or that Paromomys is really a divergent offshoot.
of the earliest notharctine ancestry toward which various tarsioids.
have converged in one way or another. The second alternative would
imply extreme antiquity of the Pelycodus pattern and the very remote
separation of Notharctinae and Adapinae, to a degree that seems:
improbable. The very tarsioid, and not particularly Pelycodus-like,
pattern of Palenochtha, which nevertheless seems almost surely to be:
a fairly close relative of Paromomys and Palaechthon, and the many
distinctly tarsioid characters of the latter genera, however electic in
their combination, also suggest that the former alternative is more
probable, as Gidley concluded. I must confess, however, that I see
no way of forming a really strong and reasonable opinion on this.
problem from the present evidence.
Genus PAROMOMYS Gidley
Paromomys GIDLEY, 1923, p. 3.
Type.—P. maturus Gidley, 1923.
Distribution.—Middle Paleocene, Fort Union, Mont.
Diagnosis—Dental formula probably 33. Lower incisor enlarged,
root extending beneath P,. Canine normal or slightly reduced.
P, present, 2-rooted. P, not enlarged, paraconid and metaconid
very rudimentary or absent, trigonid apex slightly higher than M;,
heel low, bicuspid. Molars with short trigonids, with closed, small,,
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 149:
quadrangular, transverse trigonid basins, paraconids small -and
closely approximated to metaconids, especially on M>-3; cusps.sub-
marginal; no metastylid. Talonid of M; greatly enlarged, with strong
third lobe with (at least) two distinct, transversely paired cusps.
P? 2-rooted. P* 3-rooted, with strong protocone, no distinct meta-
cone. Upper molars primitively tritubercular, without mesostyle,
protostyle, or hypocone, but with a ridge from the protocone swinging
around the posterointernal corner, which is much expanded and
basined. Internal bases generally bilobed.
The morphology of the genus is described under its type species,
and the distinctive characters of the second species mentioned under it.
PAROMOMYS MATURUS Gidley
Figures 30, 31; Puats 7, Figures 2, 2a, 3, 3a; Puats 8, Ficurss 2, 2a, 3, 3a:
Paromomys maturus GipLEy, 1923, p. 3.
Type.—U.S.N.M. no. 9473, right lower jaw with P,-M; and anterior
alveoli. Collected by A. C. Silberling.
Horizon and locality —Al\l known specimens from Gidley Quarry,
Fort Union, Middle Paleocene horizon, Crazy Mountain Field, Mont.
Diagnosis —Trigonids M,-, notably narrower than talonids. P*
strongly transverse. Internal bases of M!~ strongly bilobed. Meas--
urements and derived statistical data given below. Dental formula
't2° (but see below). All teeth closely placed, without diastema.
Discussion.—There are six specimens in which the anterior alveoli
are all shown, although in none are their rims unbroken. One of
these, as noted by Gidley (1923, p. 9—Gidley mentions two, but the
other is not of this species), has a minute pit external to and between
the incisor and canine, which might be an alveolus for a vestigial
incisor. It could, however, be a mere break, and as none of the other
five specimens shows it this is a more probable explanation. I, was
thus probably absent, and if ever present was vestigial and oftener
lacking.
The incisor and canine are unknown except by their alveoli. The
incisor was large, its root slightly compressed laterally, and was semi-
procumbent, its root extending to beneath the posterior end of P»
or anterior end of P;. The canine was considerably smaller, its nearly
circular root with about half the (maximum) diameter of J,. It is less
procumbent, and its root is shorter than that of I,, the root of which
passes beneath it. The one canine root occupies about the same-
space as the two of P».
P, has two separated, divergent roots. The crown is high, slender,
very slightly procumbent, andsomewhatrecurved atthe tip. Theouter-
face is convex, the inner excavated anteriorly and posteriorly, adjacent
to curving, vertical sharp anterointernal and posteroexternal crests...
150 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
On one specimen (9479) there is a very minute anterior cuspule, high
on the crown, which is only very vaguely suggested on a second speci-
men surely of the same species (9676). There is a low and very
small heel, with a minute cusp at the posteroexternal corner of the
=
FIGURE 30.—Paromomys maturus Gidley, U.S.N.M. no. 9473, right lower jaw: a, Crown view; 6, internal
view. Four times natural size. (After Gidley, 1923, fig. 1.)
FIGURE 31.—Paromomys maturus Gidley, U.S.N.M. no. 9540, left upper jaw: a, Crown view; 0, external
view. Four times natural size. (After Gidley, 1923, fig. 2.)
tooth, at the base of the posterior crest, from which a ridge passes
downward and internally to the posterointernal corner.
P,; has about the same length and height as P, but is considerably
wider and more robust. The anterior crest is median near the apex
and turns inward below this, an accentuation of the slighter curve of
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 151
this crest on P;. The posterior crest is less curved and is only slightly
external to the midline, the tooth being much more swollen external
to it than is P;. The heel is more definite, much wider, the cusp less
external, and the ridge less sloping.
P, is much longer and wider and somewhat higher than P;, shorter,
slightly narrower and somewhat higher than M,. Aside from its
greater size, it differs from P; chiefly in the much stronger heel. A
_ small cusp appears at the posterointernal angle, and a ridge running
anteriorly from this tends to close a small basin. A minute cuspule
may appear about halfway up the crown on the inside of the anterior
edge, but this rudiment is often lacking even on unworn teeth. Simi-
larly, a very vague rudiment of a metaconid appears on the most
progressive variants (e. g., 9545) but is oftener absent.
The molars have small trigonids and large basined heels. On M,
the trigonid is well elevated and is directed somewhat forward, while
on M,_; it is progressively lower. On M,-, the talonid is considerably
wider than the trigonid, the inner face of the tooth base being along
a straight anteroposterior line and the outer face strongly oblique.
On M; the trigonid and anterior half of the talonid are of about equal
width. The enamel is nearly smooth, but on completely unworn
teeth the basin is somewhat wrinkled. Variable, crenulated external
cingula are developed on all the molars except on the third lobe of
M;. There are no internal cingula.
The paraconid is present on all the molars and is anterior and
slightly external to the metaconid. On M, it is definite and well
separated from the metaconid, although small. On M,-,; it is much
closer to the metaconid and is almost fused with the latter, disappearing
with slight wear. On M, the metaconid is about equal to the proto-
conid, and on M,-; it is higher. On all, the metaconid is internal and
slightly posterior to the protoconid, and the two are connected by a
notched crest. Another, less prominent crest runs forward and slight-
ly inward from the tip of the protoconid to the anteroexternal angle
of the tooth, then internally along the anterior rim to the paraconid,
enclosing a short, transverse, very shallow and small trigonid basin.
M,-2 have typical hypoconid and entoconid of about equal height.
The sharp basin rim is vaguely expanded in the hypoconulid region,
but no definite apex is here formed. There are no metastylids.
The heel of M3; is very elongate, with two definite lobes each pri-
marily with two large cusps, one external and one internal. The pos-
terior, or hypoconulid, lobe may be further complicated by the incipi-
ent fission of one or both of its cusps, and adventitious cuspules may
even appear in the basin, the exact structure of this part being highly
variable, although its basic features, the extension of the basin into a
third lobe and the strongly double hypoconulid, are constant.
119212—37—11
152 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
The symphysis is short, unfused, and relatively deep. There is a
larger mental foramen beneath P, or the posterior part of the canine
and another, smaller, beneath P,. The dental foramen was far back
of the molars and slightly below the alveolar level. The angular
process is not completely preserved in any case but was directed
decidedly downward, as well as backward, and evidently was strong
and more or less styliform. Condyle and coronoid are not preserved.
The upper canine is represented only by part of its alveolus in one
specimen (9540). This suggests that it was strongly reduced, the
portion of alveolus preserved indicating a root not larger than the pos-
terior root of P?. P?-* are known only from alveoli. Each had a
small anterior and large posterior root. On P? the disparity is greater,
and the posterior root more transverse, but even it apparently does not
have a third root, and the inner heel, or protocone, must have been
small.
P*is a large, transverse tooth with three separate roots. The high
outer cusp, paracone or amphicone, is vaguely triangular and is
single, only very slight inner and outer vertical depressions suggesting
the incipient appearance of a metacone on its posterior slope. There
is a small, distinct parastyle and a much less distinct metastyle higher
on the crown than the parastyle. The posterior half of the outer face
has a narrow, sharp basal cingulum. The protocone is large and
definite but lower than the amphicone, and its apex is anterior to a
median transverse line across the tooth. From it a small sharp,
cingular crest runs to the parastyle. Another crest falls away directly
posteriorly from its apex to the expanded posterointernal angle of the
crown, where it turns nearly at right angles and becomes a well-
developed but simple posterior cingulum. A minute, isolated cuspule
appears in the position of a metaconule.
M! and M? are almost identical in structure, differing only in outline
and proportions. Paracone and metacone are strong, distinct, and
nearly equal, the paracone very slightly larger. There is a strong
external cingulum, rising at the anteroexternal corner without definitely
forming a parastyle cusp. The metastyle is likewise small and vague
but is more nearly cuspidate. There is no trace of a mesostyle. The
inner face of the tooth is flattened and has a distinct, median, vertical
groove that divides it into two basal lobes, the posterior lobe being on
M! slightly and on M? distinctly larger. These lobes, however, do not
correspond to distinct cusps. There is only one cusp, the protocone,
which is on the posterior lobe very near the distal end of the groove.
Although larger, the protocone has the same structure as on P* with
the addition of a ridge to the metaconule, departing not from the
apex but from the posteroexternal slope. The anteroexternal ridge,
as on P‘, runs to the anteroexternal corner, or to the parastyle (here
less distinct) but at its midpoint here has a cuspule, a protoconule, the
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 153
posteroexternal base of which also meets a small ridge descending the
inner face of the paracone. This protoconule is very small, and the
metaconule is still smaller and indistinct. The posterior crest from
the protocone apex forms a sharp loop around the expanded posteroin-
ternal corner of the crown, thus making the teeth distinctly quadrate
although no hypocone is present.
M$ is shorter than M'~?, with the whole posterior half, most notice-
ably the metacone and posterointernal loop, much reduced. The
internal base has only one lobe. On one specimen (9542) there is no
groove, and on the other (9540) it is very slight and does not reach the
base.
TABLE 80.—Numerical data on lower teeth of Paromomys maturus
Variate N R M o V
Ibs eee | 18 2.3—2.8 |2.556+0. 026 |0. 112+0. 019 4.4+0. 7
Wily eese e 18 1.6—1.9 |1. 778+0. 022 |0. 092+0. 015 5. 240.9
TDN bree ae ee a 21 2.8—3.2 /3.005+0. 020 0. 090+0. 014 3.0+0. 5
\T 0 7 ee Pall 2.0—2.3 /2. 288+0. 018 |0. 084+0. 013 3. 8+0. 6
TEA (heelys a 20 2.9—3.2 |3.040+0. 024 |0. 108+0. 017 3.5+0. 6
WWEMiG ee. 20 2.2—2.5 |2.355+0. 017 |0. 07440. 012 3.1+0.5
Migs a leer 14 3.3—3.8 |3.59 £0.03 |0. 130+0. 025 3.640. 7
WWalVigean eS 175 1.8—2.1 |1.994+0. 006 |0. 025+0. 004 1.3+0. 2
WPM ess 13 0. 77—0. 89 |0. 88740. 009 |0. 03440. 007
LM,:WM,2_--| 19 1. 25—1. 41 /1. 298+0. 011 |0. 046-0. 007
EM; LM,____| 10 J. 16—1. 31 |1. 215+0. 014 |0. 046+0. 010
TaBLe 31.—Measurements of individual specimens of Paromomys maturus
TYPE LOWER Jaw!
Ps Mi M2 M; |
M LP, LM2 LMs:
“3 | IM: | WM: | LMs
L W L W L W L W
Mm Mm Mm Mm Mm Mm Mm Mm
7Ast%) ies ond 222 | oul 2.3 3.6 1.9 9.0 0. 81 1.35 1.16
CHARACTERISTIC UPPER DENTITIONS
P4 M! M? M3
U.S.N.M.no. peer vont (tly SE sole heer ill cont gyi fy Mag
LM! LM} LM?
L Ww L W L W L W
Mm | Mm} Mm | Mm | Mm | Mm | Mm | Mm
pai | ee enna ae Sea 2.9 3.4 2.9 4.0 2.9 4,1 2.3 4.1 8.3 1.00 1.41 0. 79
OAD Nae eer 85. *h 225) 3.0 2.6 3.8 2.6 4.0 2.0 3.6 7.4 0. 96 1, 54 0.77
1 These measurements have been taken, and ratios calculated, on 30 different specimens, but these are most
usefully summed up by the statistical data derived from them and wherever possible in this memoir I do not
publish the long tables of raw measurements. Data for Mii-3 have not been calculated. Although at first
sight this would appear to be the best single size measurement, in fact it depends to so great a degree on
crushing and other extraneous factors as to be highly inaccurate and hence of little value.
154 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
The infraorbital foramen is high and narrow and lies immediately
anterior to the anterior root of P*. Very little of the orbital rim is
preserved, and I see no basis for supposing it larger or smaller than in
any possibly related group. It seems probable that it extended little,
if any, farther forward than P*.
The principal numerical data on lower teeth of this species are given
in table 30 (see also fig. 3).
The highly homogeneous character of the sample, and by inference
the only slightly variable nature of the species, is very striking. All
the coefficients of variation are remarkably low and even the highest,
5.16 £0.86, is very commonly exceeded in races that are pure in the
strictest sense.
There are too few upper jaws to calculate derived statistical data.
PAROMOMYS DEPRESSIDENS Gidley
Figure 32; PLATE 9, FIGURE 7
Paromomys depressidens GipLEY, 1923, p. 4.%
Type.-—U.S.N.M. no. 9546, part of right upper jaw with P*-M?.
Collected by A. C. Silberling.
Horizon and locality—AlL known specimens from Gidley Quarry,
Fort Union, Middle Paleocene horizon, Crazy Mountain Field, Mont.
FIGURE 32.—Paromomys depressidens Gidley, U.S.N.M. no. 9485, left lower jaw, crown view. Four times
natural size. (After Gidley, 1923, fig. 3.)
Diagnosis —Trigonids of M,_2 nearly as wide as talonids. P* less
transverse than in P. maturus. Bases of M'* less strongly bilobed.
Size notably smaller; length M, (mean of three specimens), negative
deviation from mean in P. maturus about eight times standard devia-
tion of latter. See also measurements in table 33. P, larger relative
to M,; ratio LP,:LM, (one specimen), positive deviation from mean
in P. maturus over three times standard deviation of latter. M, wider
relative to its length; ratio LM,:WM, (mean of three specimens),
negative deviation from mean in P. maturus nearly three times stand-
ard deviation of latter.
Discussion.—l,—-P3; are known only from their alveoli, which are
developed about as in Paromomys maturus. Of the two specimens
showing these alveoli, one (9416) has a possible alveolus for a vestigial
I,, and the other (9482) does not, so that, as in P. maturus, this tooth
was either absent or inconstant. P, is slenderer and somewhat less
64 In referring to Gidley’s description, note that the text has been transposed. The text in Gidley, 1923,
from p. 5, line 12, beginning ‘‘Several upper-jaw portions . . .’’ to p. 6, line 3, ending ‘‘. . . above the junc-
tion of P3 and P4”’ is made part of the description of P. depressidens but in fact refers to P. maturus and evi-
dently was meant to follow p. 4, line 12, of text, after ‘‘. . . as in Notharctus nunienus (Cope).”
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 155
progressive than in P. maturus, being to some extent intermediate in
structure between P; and P, of that species. The supposed depression
of the molar trigonids, stressed by Gidley, involves slight differences
that defy accurate measurement. To my eye they do not appear at
all less elevated than in P. maturus. The trigonids of M>_; are rela-
tively slightly shorter, and the paraconids may be still more nearly
connate with the metaconids. More definite is the fact that on M, the
trigonid is nearly as wide as the talonid, while in P. maturus it is
definitely narrower. Perhaps in keeping with the smaller size, the
heel of M; is rather simple, and although it has the basic structure of
P. maturus in some variants the third lobe is less wide and its two main
cusps less distinct.
The available upper teeth of this species are all deeply worn, and I
believe that the characters given by Gidley, ‘‘cusps and lophs depressed
and basins shallow; protoconules present but less well defined than
P. maturus; metaconules absent’’, are all due to this wear, or at least
that the wear makes it impossible to know whether these are true
morphological characters or not. P* is much less transverse than in
P. maturus, and the inner sides of the bases of M'~? are less strongly
bilobed. Otherwise the structure seems to be very similar, as far as it
can be surely determined.
The species is decisively distinct from the genotype, and there can
be no question as to its validity in spite of the fact that P. maturus and
P. depressidens were absolutely contemporaneous and both are known
only from the same very limited locality. These facts and the very
TABLE 32.— Measurements of known specimens of Paromomys depressidens
LOWER JAws
LP, LM2 LM;
WEE NeMomoasiriny rea lah alee ii cade cee Pe Pee aay A SLs
Mm | Mm | Mm | Mm | Mm | Mm | Mm | Mm
O48 petrvees ge beser | ie | bees 2.0} 1.6) 2.0) 1.8) 26) 1.5 (EAT 2 oes Sc 1G 1.30
OC ieee OE OU Ma ii baal ate -29h bee a es he J a 2.8 | 1.6 6.9 0. 95
O28 Zeca eS dee LS Shee see p50 | Nios) ses je! [game 5s | hae Li) a ees EIS Te 1, 22 1. 23
OF1G1S 2 ees 22 eee 1 tah |e) 9.77 eae | Se eS Ss PECIH a Sth ee ened Pe ee eee Sed eee ere Ts 1, 21
UPPER JAWS
4 A 2 3
P M M M a | bet | wM?| ums
ESS NGWE. 0. 3a rl ate aga Ie Paull Gail REL Eee aL PE ATi IGeol oop
Mm | Mm|Mm|Mm|Mm | Mm | Mm | Mm
eee 159) 2305) 250) 256) 220 ees. 0 ERS ey / 5.7 0.95 1.50 0.75
156 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
marked specific distinction suggest that complete, unworn dentitions
might prove generic distinction, but the material actually in hand does
not warrant such a conclusion.
As the samples are small, measurements of all known specimens are
given in table 32 (see also fig. 3).
Genus and Species Undetermined
Cf. PAROMOMYS
In 1932 Silberling and I found at Loc. 13 a single left M', apparently
representing an otherwise unknown primate. It resembles Plesiadapis
anceps but not very exactly and is still less like other species of that
genus. It is probably too small to belong to Plesiadapis rex, which
occurs at the same locality. It resembles Paromomys maturus more
closely than any other species with which comparison has been made,
but it is more transverse, has the inner face even longer and more
sloping, and has the anterointernal, not posterointernal, basal part
definitely more projecting. It also resembles the most primitive
species of Pelycodus but could not belong in that genus. Such an
isolated tooth is inadequate for generic, or even for certain family
identification, but its presence seems worth recording.
Genus PALAECHTHON Gidiey
Palaechthon Gipury, 1923, p. 6.
Type.—P. alticuspis Gidley.
Distribution.—Middle Paleocene, Fort Union, Montana.
Diagnosis —Dental formula probably ~->3. Lower incisor and
canine about as in Paromomys, or possibly incisor slightly larger and
canine slightly smaller. Roots of P, less divergent or incompletely
divided. P, larger relative to M,, talonid as in Paromomys, but
trigonid with distinct, subequal paraconid and metaconid. Molar
trigonids very similar to Paromomys but on M,_3 paraconid slightly
more distinct, lower on the crown, and less marginal. M; with double
hypoconulid, but third lobe less strong than in Paromomys. Trigo-
nids more elevated. Upper molars somewhat more transverse than
in Paromomys maturus, internal bases less distinctly bilobed, and
posterointernal expansion jess marked.
PALAECHTHON ALTICUSPIS Gidley
Puate 7, Figure 1; Puate 9, Ficurss 5, 6
Palaechthon alticuspis GipLuy, 1928, p. 6.
Type.—U.S.N.M. no. 9532, right lower jaw with P.-M,. Collected
by A. C. Silberling.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 157
Horizon and locality—All known specimens from Gidley Quarry,
Fort Union, Middle Paleocene horizon, Crazy Mountain Field, Mont.
Diagnosis.—Sole known species of genus as redefined. See mor-
phological and numerical data (table 33).
Discussion.—From their alveoli, in two specimens (9532 and 9534),
J, and C are much as in Paromomys maturus, but the incisor is perhaps
relatively a little larger and the canine still smaller, its alveolus
occupying distinctly less space than the alveoli of P,. There is no
evidence of a second incisor.
The alveoli of P, are confluent, and in one specimen the roots are
fused, in another barely separate. P, and P; are similar to each other
and to those of P. maturus. Pz» is slenderer and slightly higher than P;
and P; has the incipient anterior cuspule more nearly distinct than Po».
P, is much more progressive than in Paromomys, having small but
distinct subequal paraconid and metaconid in all cases, whereas in
Paromomys these cusps are either barely incipient or entirely absent
on P;. The talonid and general structure are, however, as in Paro-
momys.
M, almost exactly resembles that of P. maturus. M3_; are also
closely similar but have the paraconid more distinct than is usual in
Paromomys, lower on the crown and also a little more external, or less
marginal. On both M, and M, the trigonid is nearly as wide as the
talonid. On M,_; the trigonid is more elevated than in Paromomys,
and the external cingulum is weak or absent on the talonid. The third
lobe of M3 is much less developed than in Paromomys maturus, but
the hypoconulid is bifid or, in one case (9430) approximately trifid.
The mandible is also much as in Paromomys. In one specimen
(9450) most of the posterior part is present, although the ends of the
three processes are broken. The inner face is nearly plane. The
coronoid is broad and apparently rose little above the articular process.
Its anterior border is nearly straight and at right angle to the alveolar
border. The condyle is far above the molar level. The large dental
foramen is far posterior to the teeth, beneath the corono-condylar
notch, and is above the alveolar level. The angle is long, slender,
styliform, and thickened, and extends backward and slightly down-
ward. Its tip was posterior to a vertical from the condyle.
P* is not known, but it has three roots and was nearly as wide as M?.
The upper molars closely resemble those of Paromomys maturus
except in being somewhat more transverse, with slenderer sharply
pointed cusps, and in the much less marked posterointernal expansion
and basining. There is an internal vertical groove, but on M! the
base is not bilobed and on M? this is barely indicated. Several of
these points are resemblances to Paromomys depressidens, and it has
already been noted that the teeth on which that species is based are
much worn and of doubtful detail. As the two species are of about
158
the same size, the status of these upper jaws is dubious, although the
lower jaws are quite distinct, and it is unfortunate that one type is
an upper jaw and the other a lower. The upper jaws are, however,
probably distinct and correctly associated with the lower jaws as
determined by Gidley. Those placed in Palaechthon alticuspis are
very slightly smaller, molars definitely more transverse, and the pos-
terointernal basin probably less developed. It seems justifiable, in
the absence of definite evidence to the contrary, to accept the identi-
fications established and thus avoid changing the nomenclature, con-
sidering the separation of the species and genera as validated by the
lower jaws and, for the present, overlooking the fact that one type is,
in fact, an upper jaw and of doubtful status.
BULLETIN 169, UNITED STATES NATIONAL MUSEUM
TABLE 33.—Numerical data on Palaechthon alticuspis
Variate N R M o Vv
19 Fre ener ets 10 1.9 -2.1 2. 030+0. 025 | 0. O78+0. 017 3.8+0. 9
Wa Vie eras See 9 ER als 76 1. 567+0. 022 | 0. 066+0. 016 4.2+1.0
1 DAI) Cm ck ek a 12 1.9 —2. 2 2. 067 +0. 024 | 0. 085+0. 017 4.1+0.8
WEMGe ee Sees: 11 1.5 -1.8 1. 682+0. 025 | 0. 084+0. 018 5. Ose Tl
LM.2:WM2_-_-!| 11 1. 17-1. 40 | 1. 28140. 021 | 0. 070+0. 015
TABLE 34.—IJndividual measurements of Palaechthon alticuspis
TYPE AND CHARACTERISTIC LOWER JAWS
Py Mi M2 M3 | LP, LM, LM;
U.S:NsVE n0s46 | TERE a GOR CLG eo LL sa Ses M1-3 LM: | WM: | LM:
L Ww L Ww L Ww L Ww
Mm | Mm | Mm}Mm|Mm | Mm | Mm | Mm
O58 2E SC a a rete 1.9 2 1.9 1.5 2.0 We Wiecsn See ee ee es 1.00 1.18
430s te Be at Rr tae 2.1 1.2 2u1 1.6 2:1 1 7. 2.4 1.3 6.5 1.00 1. 24 1.14
O48 se. Se eee 2.0 12 2.1 1.5 2.1 1.6 2.3 1.4 6:3 0.95 1.31 1.09
UPPER JAWS (ONLY TWO ARE KNOWN)
M! M? M3
U.S.N.M. no. M!-3 “ ae
L Ww L WwW L WwW
Min Mm Mm Mim Mm Mm
Q550 Fee Se vee te 1.9 3.0 Ny / 3.0 1.3 2.5 5.3 1.76 0. 76
OOD IEE Sear eee See 1.9 3.0 1.9 5 976 fe aa le F< Mi ante 1. 68
Genus PALENOCHTHA Simpson
a lenochtha Simpson, 1935d, p. 281.
Type.—Palaechthon minor Gidley.
Distribution.—Middle Paleocene, Fort Union, Montana.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 159
Diagnosis.—Dental formula probably 3. Anterior lower denti-
tion shorter than in Paromomys or Palaechthon and apparently with
one tooth absent, probably P.. Py, of about the same length relative
to M, as in Palaechthon alticuspis but relatively higher, with no sign of
the metaconid and only vague rudiment of the paraconid. My,-»,
similar to those of Palaechthon, but M; with smaller third lobe and
single hypoconulid. Upper molars similar to those of Paromomys
and Palaechthon but very slender, transverse, and more triangular.
Posterointernal expansion weak. Inner base not bilobed. M#
shorter relative to M?.
Discussion.—In describing Palaechthon minor, Gidley (1923, p. 8)
said: ‘“‘Most of the differences noted above suggest for the species just
described a slightly different line, or direction, of development than is
indicated in P. alticuspis. It is possible, therefore, that more complete
materials may prove that these two species do not form a natural
generic group.”” Although more complete materials are still lacking,
I do not see how this species can be placed in Palaechthon. The
further reduction of the anterior teeth, the absence of a metaconid and
of a distinct paraconid on P, (not explicitly mentioned by Gidley),
and the single hypoconulid on M; are just such differences as are used
to distinguish genera among all early primates. While it is true, as
Gidley notes, that the upper molars differ less from Palaechthon
alticuspis than do the lowers, still the differences are rather more
marked than are those between the latter species and Paromomys
depressidens. Unfortunately, the anterior upper teeth, which often
show more marked generic characters, are unknown, but I think there
can be no doubt that the genus is distinct.
PALENOCHTHA MINOR (Gidley)
Figure 33; Puate 10, Ficure 1
Palaechthon minor Gip.Ey, 1923, p. 7.
Type.— U.S.N.M. no. 9639, right lower jaw with P,-M; and anterior
alveoli. Collected by A. C. Silberling.
Horizon and locality—All known specimens from Gidley Quarry,
Fort Union, Middle Paleocene horizon, Crazy Mountain Field, Mont.
Diagnosis—Sole known species of the genus as described above.
See description below and measurements in table 35.
Discussion.—Teeth anterior to P, are represented only by alveoli
in the type and in no. 9631. Both show an alveolus for a large, some-
what compressed, procumbent incisor, followed by a smaller, more
erect alveolus, evidently for a canine. Between this and P, there
appears to be only a small double alveolus, or two very small alveoli
confluent at their mouths. It is highly probable that this lodged one
tooth, P;, and in this event P,-, must have been missing. There
160 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
appears, however, to be no diastema, and the antemolar region of the
jaw is relatively shorter than in the other genera here considered, what-
ever may have been the exact number and homologies of the teeth.
P, is relatively higher, slenderer, and simpler than in Palaechthon.
In the two available specimens there is no clear trace of a metaconid,
and the paraconid is represented only by a very rudimentary and
scarcely visible angulation of the anterior edge. The heel is short but
is relatively broad and has a rudimentary basin and two very small
and poorly differentiated posterior cuspules.
M,_» are almost identical in structure with those
of Palaechthon. The trigonid of Ms; is also closely
similar, but the talonid is different. It is reduced,
more pointed posteriorly, with the third lobe de-
Ficure33.—Palenochtha cidedly narrower and less clearly differentiated, and
minor(Gidley),U.SiN.Ma
the hypoconulid apparently single.
no. 9590, left upper mo- ae
lars, crown view. Four In the upper dentition, only M!~* are now known.
rMidley, 102, het) Lhese are basically similar to those of Palaechthon
but give quite a different superficial impression by
reason of their more delicate structure, more transverse and triangular
outline, and the accentuated forward twist of the protocone, present
in the other primate genera but here most strongly developed. Para-
style and metastyle are distinct and subequal, as are protoconule
and metaconule. The inner face of the protocone is flattened and
bears a faint vertical depression, but the base is not at all bilobed. The
posterointernal basin or expansion is only faintly indicated, less de-
veloped than in the other genera. M® is short, rather strongly tri-
angular, and developed analogously to that of Palaechthon.
TABLE 35.—Individual measurements of Palenochtha minor
TYPE AND PRINCIPAL REFERRED LOWER JAWS
P4 Mi M2 M3
U.S.N.M. no. |—————_|—______|—________|______| yw, Es lh reas
LM: | WM: | LM;
igh Bae ee eae LSP OLS ysl aT Desa aL 15 O29 4.3 1.00 1.08 1,15
GGdIoL 251 Ace Lie DEMOS Sle 2 al eel OP eal See etOni se soen |e I2e22)| € eee ee 0. 92 1.30
9636-52 o aoe net See aeons WSuliq LaOuiy 283 | ol Aad at 059 Cea a eee 1.18 1. 08
UPPER JAWS (ALL KNOWN)
Mi! M? M3
WM?| LM
U.S.N.M. no. SS | ey I te
LM? } LM?
9590) seb piss 2. fe a see 1.3 2.0 1.2 2.0 0.8 1.6 3.8 1. 67 0. 67
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 161
Family CARPOLESTIDAE Simpson, 1935
As was pointed out in describing Carpolestes (Simpson, 1928, p.
10), Hlphidotarsius supplies a good morphological ancestry for the
very peculiar and aberrant genera Carpodaptes Granger and Matthew
of the Tiffany and Carpolestes Simpson from Tiffany or slightly later
equivalents in the Fort Union. The present opportunity to compare
the genotypes of the three genera at first hand fully confirms this and
leaves no doubt that they are closely related.
Elphidotarsius and Carpolestes show the same highly characteristic
basic structure throughout P-M;. Carpodaptes has P, more enlarged
than in Elphidotarsius, its apical cuspules all in a straight line and one
more in number. On M, the trigonid is still more elongate, and the
paraconid almost directly anterior to the protoconid. Other struc-
tural distinctions are very slight and unimportant. In Carpolestes P,
is still larger, its cuspules increased to seven or eight, its heel elevated
to the trigonid level of M,;. On M, the paraconid and protoconid are
exactly in the same longitudinal line and continue without a break
the cuspule series of P,. The structural sequence Elphidotarsius—
Carpodaptes—Carpolestes is almost perfect (also in the size of the
known species) and may be a direct phylogeny, although the possible
age difference between the last two genera seems too small to permit
such a marked structural advance in a direct descendant, and it is
more likely that some collateral evolution is involved.
Upper teeth are as yet known only in the genera Carpolestes (Car-
polestes dubius Jepsen; see Jepsen, 1930a) and Carpodaptes. The
molars are of primitive tritubercular type, with distinct hypocone,
more or less closely paralleled in some primitive Eocene primates
(e. g., Omomys, Caenopithecus, Pseudoloris, and others). P*~*, how-
ever, are very extraordinary and unlike anything known in any other
primate or indeed any placental mammal, to such a degree that when
the first isolated example of one of these teeth was found J hesitantly
referred it to the Multituberculata (‘‘Litotherium” © Simpson, 1929,
p. 9), and this remarkably bad guess was only corrected when Jepsen
found associated premolars and molars. Like the last premolar of
Piilodus, both P? and P* have three longitudinal rows of cusps.
These premolars are much unlike those of any tarsioid, as is Ps, but
it may confidently be predicted that P** of Elphidotarsius, when
found, will distinctly approach the normal tarsioid type, as does P,
of that genus. P** of Carpodaptes are indeed closer to Carpolestes,
but they show some approach to more normal structure.
65 A strict synonym of Carpolestes Simpson, 1928. The retention of Carpolesies as the definitive name is
not only preferable, as Jepsen suggests, but also the only possible course in accordance with the rules of
nomenclature,
162 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
The dental formula is also most completely known in Carpolestes
dubius, in which it is ==, as in Paromomys. The incisor is en-
larged but does not extend beneath Py, also as in Paromomys, but the
canine is more reduced. In both Carpolestes and Carpodaptes P.-;
are reduced to 1-rooted vestiges with buttonlike crowns.
Noting these divergent specializations, but also the strong hint of
tarsioidlike upper molars, in the most specialized genus of the phylum
in characters not known in Elphidotarsius, we may expect the latter
to cast more light on affinities as far as its more scanty remains go.
P, in this genus could easily be derived from one like that of, say,
Palaechthon, but it is already too specialized, and its structural ancestor
must have been too generalized, to cast any real light on affinities.
M, also shows what may be taken as the beginning of a narrowly
phyletic specialization in its elongate trigonid. Otherwise it is much
like that of many tarsioids but of too generalized a heritage to give
decisive evidence. M,_; are almost exactly like those of Pronothodectes,
so much so that were this form known from those teeth alone it would
have to be defined as a species of Pronothodectes. They also resemble
to a marked degree those of Eocene primates of other groups, such
as ?Omomys vespertinus and, in less degree, Pelycodus. As far as I know
they do not so closely resemble any genus not now considered as
primate. The characters that are distinctive from the most generalized
tuberculosectorial pattern and that are not clearly habitus characters
or otherwise neomorphs of this very restricted phylum all appear to
me to be definitely primate. To this extent I cannot agree with Jepsen
(1930a, p. 523—he was, however, dealing only with the much more
aberrant terminal genus Carpolestes and had not recognized the
relationship to Elphidotarsius) that “it is possible to select suites of
characters which, taken by themselves, would place Carpolestes in any
one of several orders.’’ I do, of course, recognize that a really defini-
tive determination of affinities is in such cases practically impossible
from teeth alone, but since teeth are, in fact, all we have I see no
useful alternative to classifying them at least tentatively as belonging
to the group they most resemble, that is, to the Primates.
The family in which these related, aberrant animals are placed was
defined and discussed in revising the Tiffany fauna (Simpson, 1935c).
Genus ELPHIDOTARSIUS Gidley
Eiphidotarsius GipLEy, 1923, p. 10.
Type.—E. florencae Gidley.
Distribution.—Middle Paleocene, Fort Union, Montana.
Diagnosis —Three lower molars and at least one premolar, dental
formula otherwise unknown. P, enlarged, equaling or exceeding M, in
66 Jepsen writes 1.0.4.3. It is, of course, impossible to say which is correct, but the form I give seems to
me slightly more probable, and it facilitates comparison by being consistent with the other formulae here
used.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 163
every dimension. Apex with four cuspules, second highest, first three
anteroposterior, and fourth slightly internal. Talonid very short,
with one cusp. M, with elongate trigonid, paraconid far from meta-
conid, no trigonid basin. M,_; with closed trigonid basins and para-
conid small, near metaconid, but distinct. Talonid of M, with well-
differentiated third lobe, posterointernal rim elevated and vaguely
including two or more apices. Protoconid reduced on M2_3. Trigonid
cusps all well in from the margin.
ELPHIDOTARSIUS FLORENCAE Gidley
Puate 10, FiaursEs 2, 2a
Elphidotarsius florencae GIDLEY, 1923, p. 10.
Type.—U.S.N.M. no. 9411, left lower jaw with P,-M;. Collected
by Dr. J. W. Gidley.
Horizon and locality — Gidley Quarry, Fort Union, Middle Paleocene
horizon, Crazy Mountain Field, Mont.
Diagnosis —Sole known species of genus as diagnosed above. See
also description and measurements below.
Discussion.—P, is a very peculiar tooth, longer, wider, and higher
than M, although not greatly exceeding the latter in any dimension.
Both sides are almost smoothly convex, but the apex is formed by
four cuspules, or serrations, of which the second is highest although
the third is slightly larger. The first three are in a straight anteropos-
terior line, the fourth slightly more internal. The very short heel has
one cusp, from which a small sharp crest descends vertically along the
posteroexternal edge of the tooth and turns into the external cingulum.
On M, the distinct but small paraconid and the larger metaconid
are widely separated and there is no trigonid basin. The metaconid
is posterointernal to the protoconid. In the talonid the hypoconulid
cannot be distinguished and the basin is not completely closed, as
there is a deep narrow notch between the entoconid and the trigonid.
On M, the trigonid is much shorter and wider, the metaconid less
posterior, the paraconid close to the metaconid although still distinct,
asmall trigonid basin present. The talonid is like that of M, but larger.
The trigonid of M; is like that of M,. The heel is modified by the
addition of a well-differentiated third lobe, the elevated posterior and
posterointernal rim of which shows some tendency to split into two
cusps, although these are not distinctly developed. On M, the proto-
conid and metaconid are of nearly equal height. On M, the protoconid
is slightly and on M; decidedly lower than the metaconid
To an even greater degree than is common in primitive mammals the
alveolar border slopes outward, so that the external faces of all the
cheek teeth are much higher than the internal.
Presumably an enlarged incisor was present, but its root did not
extend under P,, and the jaw is broken off at this point.
164 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Measurements of the only known specimen are as follows: Length P,,
1.5; width P,, 1.2; length M,, 1.2; width M,, 1.2; length Mb, 1.2;
width Mo, 1.3; length M3, 1.7; width M3, 1.0; M,_3, 4.4; ratio length
P, : length M,, 1.25; ratio length M.: width Mb, 0.95; ratio length
M; : length Ma, 1.42.
Family PLESIADAPIDAE Trouessart, 1897
Although quite distinctive and manifestly in the plesiadapid line,
Pronothodectes shows a definite resemblance to the other primate
genera in this fauna. Elphidotarsius represents the beginning of a
divergent line, especially in the first stages of specialization of P,, but
there is a remarkably detailed resemblance in the molar structure.
The paraconids are more distinct in Elphidotarsius and the trigonid of
M, more expanded anteroposteriorly. The talonid cusps of M,_» are
less distinct. Except for the here very slight difference in the para-
conid, the highly characteristic M; is almost identical in the two gen-
era. The resemblance to Paromomys, especially P. depressidens, in
the lower teeth is also very marked, the noteworthy differences aside
from the divergent emphasis in the anterior teeth being in the some-
what more progressive, or slightly different, specialization of the molar
trigonids and the aberrant heel structure of M,; of P. depressidens.
The trigonid structure, but not that of the heel of M; is somewhat
more closely approached in Palaechthon.
The very incomplete knowledge of Pronothodectes upper teeth sug-
gests a basic resemblance to those of other genera here described, but
makes it easier to see a few outstanding differences: the better para-
cone-metacone separation and strong conule of P* and the less-
marked posterointernal molar expansion in Pronothodectes, all of which
are resemblances to Plesiadapis.
There can be no question that Gidley was right in considering Prono-
thodectes as closely related to Plesiadapis (‘‘Nothodectes’’). The prin-
cipal differences are clear from the description. Pronothodectes has
the enlarged incisor less procumbent, tooth reduction considerably
less advanced and diastema not developed, cheek teeth less depressed
and of somewhat simpler detail. In all these respects and also in the
smaller size of its species, Pronothodectes is more primitive than Plesia-
dapis, to which it seems surely to be ancestral in a structural, and
perhaps also in a literal sense.
Pronothodectes represents the earliest known member of a primate
phylum analogous to the Elphidotarsius-Carpodaptes-Carpolestes
phylum but with a greater known range in space and time. Its
principal terms are Pronothodectes, middle Paleocene of North America,
Plesiadapis, upper Paleocene of North America and Europe and, prob-
ably, lower Eocene of North America, and Platychoerops, lower Eocene
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 165
of Europe. The European Cheiromyoides Stehlin is a contemporary
and close relative of Plesiadapis.
Nothodectes Matthew is clearly a synonym of Plesiadapis, as pointed
out by Teilhard and accepted by all subsequent students.* Jepsen
(1930 and 1934) tentatively placed Plesiolestes in this group, but the
belief that it does not belong here has already been expressed above.
He also (1934, p. 290) rejects my redefinition (Simpson, 1929c) of
Platychoerops and its separation from Plesiadapis, but I have already
defended this at some length (1935c).
Cheiromyoides Stehlin, accepted as valid by Abel, Jepsen, and
others but rejected as a synonym of Plesiadapis by Teilhard, differs
less from typical Plesiadapis than does typical Platychoerops. It evi-
dently represents an only slightly divergent and, as far as known,
sterile side branch of the phylum.
Genus PRONOTHODECTES Gidley
Pronothodectes GrpLHyY, 1923, p. 12.
Type.—P. matthewi Gidley.
Mistribution.—Middle Paleocene, Fort Union, Montana.
Diagnosis.—Dental formula so Lower incisor mucb en-
larged, semiprocumbent, root laterally compressed. Canine (or
possibly P,) small, slightly procumbent. P, 1-rooted. P, with
quadrate base, short, high trigonid portion, no paraconid or meta-
eonid. Talonid large with a single cuspule. Paraconid distinct on
all molars, anteroexternal to the metaconid and progressively nearer
the latter from M, to M3. No metastylid, but a vague cusp on the
hypoconid-trigonid crest. M; with third lobe and elevated postero-
internal rim with two or more poorly differentiated apices. P* with
separate subequal paracone and metacone apices, their bases con-
fluent, large conule mass, and strong protocone, which is, however,
less expanded than in Plesiadapis. Upper molars Plesiadapis-like
but simple, without major crenulations or secondary cuspules, and
probably lacking the mesostyle (although this may be removed by
wear in the known material).
PRONOTHODECTES MATTHEW I Gidley
Puate 8, Figure 1; Puate 9, Fiagurus 2, 11, 12; Pyare 10, Ficurss 3, 3a
Pronothodectes matthewt Gidley, 1923, p. 12.
Type.—U.S.N.M. no. 9547, part of right maxilla with P*-M?.
Collected by A. C. Silberling.
Paratypes.—U.S.N.M. no. 9332, left lower jaw with incisor root
and crown of ?C, P2, Pu, and M,-3. Collected by Dr. J. W. Gidley.
67 It is, however, certain that Nothodectes gidleyi Matthew is specifically distinct from the European
Piesiadapis triscuspidens Gervais.
166 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
U.S.N.M. nos. 10005 and 10044, isolated upper incisors (pertinence
dubious). Collected by A. C. Silberling.
Horizon and locality All known specimens from Gidley Quarry,
Fort Union, Middle Paleocene horizon, Crazy Mountain Field, Mont.
Diagnosis—Sole known species of genus. See also description
below.
Discussion —The lower dentition is crowded, with no diastema.
I, is a very large, laterally compressed, nearly procumbent tooth.
Its crown is not known. Immediately above and behind the root of
I, is a shallow, very small, and somewhat doubtful alveolus, probably
for a vestigial I,. The following tooth, probably a reduced canine,
is also small and 1-rooted. The root is slightly procumbent, the
rather formless crown more so, as it projects obliquely upward and
forward from the root.
While Dr. Gidley did not discuss these anterior teeth, he gave the
dental formula as jyoroa3; from which he evidently considered the
first alveolus as doubtful and the tooth just mentioned as a first pre-
molar. While the question cannot be answered definitely, the formula
yor1133 seems to me much more probable. The morphology is
indecisive, but in later plesiadepids P14, are always lacking and in
probably related groups (especially the tarsioids) are apparently
among the first teeth to be lost, while the canine is more tenacious,
being still present in the upper, although not in the lower, jaw of the
much more advanced genus Plesiadapis and seldom or never absent in
the tarsioids even though it may be reduced.®
P, is a simple tooth with one vertical root and a slightly procumbent
crown excavated on the inner side and with a small 1-cusped heel.
P; has two roots and is not reduced relative to Py. Its crown is not
known. P, is similar to that of Plesiadapis, but its base is more
quadrate, the trigonid portion is relatively shorter and higher, the
heel is at least as large, relatively, or a little larger, but its transverse
posterior crest rises to one apex, rather than two as usual in Plesiadapis.
The paraconid is distinct on all the molars and is anteroexternal to
the metaconid. From M, to M; it is progressively closer to the meta-
conid and relatively smaller. The protoconid is about as high as the
metaconid on M,, and on M; is somewhat and on M; much lower than
the metaconid. The talonids of M,-2, which are considerably wider
than their trigonids, are simple and basined. <A hypoconulid can be
distinguished but is poorly differentiated. There is also a poorly
developed cusp on the crest from the hypoconid to the posterior base
of the trigonid. The entoconid-metaconid crest is notched. There
isno metastylid. M, is distinguished by the expansion of the posterior
end and the development of an elevated posterointernal rim, into
68 Gidley gives the formula 72.71 or 0.74.3 for the upper dentition, but this-is presumably an inference
as no specimens show anything more than that there were three upper molars and at least one premolar.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 167
which enter entoconid and hypoconulid and on which other, variable
cuspules are probably developed, although obscured by wear on the
known specimens.
The horizontal ramus of the mandible resembles that of Plesiadapis,
but the symphysis (and incisor) are less inclined, and the constriction
at the diastema of Plesiadapis is absent, as is the diastema. The
larger anterior mental foramen is beneath P, and the smaller posterior
foramen beneath P,.
The single upper jaw fragment referable to this species has only
4_M?, and these are much worn and somewhat corroded. P* has
the paracone and metacone as well separated as in Plesiadapis, a large
conule mass usually considered a protoconule in this group, but from
its central position it could be either this or a metaconule, and a dis-
tinct protocone apparently higher but less expanded than in Plesia-
dapis. The molars seem to resemble those of Plesiadapis closely but
to be somewhat simpler, with few or no secondary cuspules and crenu-
lations. The anterointernal corner is more evenly rounded, not
emarginate. No mesostyle can be seen. It may have been removed
by wear, but probably was absent.
TABLE 36.—Individual measurements of Pronothodectes matthewi
LOWER JAWS (ALL KNOWN)
P; M, M2 M3
LPs LM2 LM3
ES UNNEIDO) Woe ala al sd |. MEIe | eel Waves, |. aN
URS) ee TS] LEG 2001), 25022505) 250 ew || 8 7.3 0. 90 0.95 1.55
Q53 Ts Soe 2 IESE eIRGr lt le ON ete Oh Re 2nOh |/ee2oplo imac aaa 7.3 0.95 0. 95 1. 60
44S sores y 22 22 set. Sees QTE QO.) 2a QSal HSAs) 21 die Au ees ee 0. 91 1. 48
ie TS ee eats OP Aa bh) VP) S| ae ee | Se ee a ee Se 0. 81
PA M! M?
U.S.N.M. no. LP! WM?
TMi LM?
1; WwW ie W i Ww
Mm Mm Mm Mm Mim Mm
Grama tivnids aly iielyts sep 1.9 2.7 2.0 3.2 2.1 3.5 0.95 1.67
Genus PLESIADAPIS Gervais, 1877
PLESIADAPIS REX (Gidley)
PuaTE 9, Fiaures 4, 13
Tetonius rex GIDLEY, 1928, p. 11.
Type.—U.S.N.M. no. 9828, isolated Mz. Collected by A. C.
Silberling.
119212—37 12
168 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Horizon and locality—tLoc. 13,8 Fort Union, Upper Paleocene
horizon, Crazy Mountain Field, Mont.
Diagnosis.—A poorly characterized species with M, very low and
broad. Dimensions of type M2, 3.7 by 3.6 mm.”
Discussion.—Gidley compared this isolated tooth in a broad way
to Absarokius and Tetonius, but his reference to Tetonius was clearly
intended to be merely provisional. The resemblance exists, of course,
but is not exact, and the tooth more nearly resembles M, of Plesiadapis,
which was poorly known to Gidley when he was working on these
primates. This is a more probable reference, although it cannot be
definitive on the basis of one tooth. The size is slightly, but signifi-
cantly, larger than for M, of P. gidleyi, and the crown is slightly lower.
There is a closer resemblance to P. anceps of the Scarritt Quarry, but
the crown has a broader, blunter aspect.
A lower incisor figured by Gidley (1923, pl. 3, fig. 13) probably
belongs to this species. It very closely resembles the corresponding
tooth of P. gidleyt.
Among the specimens found by Silberling and me at Loc. 13 in 1932
are two probably referable to this species. One is a right M,, like
that of P. anceps except for its wider lower aspect and stronger external
cingulum. It measures 3.3 by 3.1mm. The other is an upper incisor
also resembling that of P. anceps but considerably heavier and wider
relative to its labiolingual diameter, the lateral apical cusp large and
directed more laterally, and with marked rugosities and small sec-
ondary cuspules on its lingual face. There is also a slightly smaller
but otherwise almost identical tooth from this locality in the Princeton
collection.
When I described Plesiadapis anceps, from a lower level near Loc.
13, I was not aware that Tetonius rex Gidley belonged (in all prob-
ability) to Plesiadapis. The species may be synonymous, in which
69 This was published as from Loc. 12 and bears that datum on the label, but it seems certain that this
is not the locality in sec. 30, T. 6 N., R. 15 E., which we relocated in 1932 and which Mr. Silberling then
noted as Loc. 12. In the first place, he records only invertebrates, no mammals, from that locality. In
the second place, it is low in the Fort Union No. 3, and less than 550 feet above the Gidley Quarry, strati-
graphically, whereas Gidley’s published and manuscript data say ‘‘nearly 4,000 feet higher in the beds than
in the ‘Gidley Quarry’ and ‘Silberling Quarry’ levels’, which is approximately true of Locs. ll and 13. In
the third place, Gidley’s data give locality ‘‘No. 12” in sec. 22, T. 5 N., R. 14 E., and Loe. 13, but not
Silberling’s Loc. 12, is in that section. Loc. 11 was formerly thought also to be in that section, but in 1932
it was relocated as across the line in section 23. In the fourth place, we found other material apparently
of the same species at Loc. 13, and at no other horizon or locality. And finally, Dr. Gidley himself seems
to have been in some doubt about this locality, for on a label of some other material he has noted ‘‘No. 12
(?13)”’, whereas there could hardly be any question about the distinction between the localities now recog-
nized as 12 and 13, since they are at widely different horizons and far from each other in the field. It seems
certain that the true type locality of this species is either Loc. 13 or Loe. 11 and highly probable that it is
13, although this point does not matter as 11 and 13 are near each other and at the same level.
70 Gidley gives 3.8 by 3.4mm, which is as close an agreement as is probable in measurements by different
workers. I have thought best in all cases to give my independent measurements, so that they are more
likely to be comparable throughout this paper.
71 The figure is of the outer side of the tooth, peculiarly oriented, and is not very characteristic. The
legend gives 12 as its locality, but the label says ‘‘12 (?13)”’, and for the reasons already given I am confi-
dent that it is really from Loc. 13, at least as they are now numbered.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 169
case P. rex (Gidley) has long priority. If, however, all the material
described above belongs to P. rez, it is almost surely distinct from
P. anceps, and even if this is not the case it is not certain from the
types that they are the same. In any event it is preferable to retain
the name P. anceps for the present, as it is a well-known and well-
characterized species, whereas P. rex is as yet very poorly known and
its specific characters are not really established. The difference in
stratigraphic level between the horizons of the two types is nearly a
thousand feet.
Order TAENIODONTA Cope, 1876
Family STYLINODONTIDAE Marsh, 1875
Matthew (Pale. Mem.) is followed in referring all
taeniodonts to a single family (with four subfamilies).
This is an extremely rare group in this fauna, with only
four specimens in the National Museum collection.
Subfamily CONORYCTINAE Matthew, 1937
(Conoryctidae Wortman, 1896)
Genus CONORYCTES Cope, 1881 FIGURE 34.—Conoryctes
comma Cope, U.S.N.M.
CONORYCTES COMMA Cope, 1881 no. 9597, upper molar: a,
External view; b, crown
FIGURE 34 view. Natural size.
Wortmann and Matthew recognized only one species of Conoryctes
in the Torrejon, and as far as I know none has ever been described from
any other formation. U.S.N.M. no. 9597, an isolated upper molar
from the Gidley Quarry; no. 9678, isolated P* from the Silberling
Quarry; and no. 9816, two upper molars from Loc. 6, seem to be in-
distinguishable from Torrejon specimens. No. 9826, from Loc. 28, a
higher level, may belong to Conoryctes but is not determinable.
Subfamily PSITTACOTHERIINAE Matthew, 1937”
Genus PSITTACOTHERIUM Cope, 1882
PSITTACOTHERIUM MULTIFRAGUM Cope, 1882
Dougiass (1908, p. 22) recorded a Calamodon in the Fort Union,
querying the generic reference. Matthew (1914, p. 390) commented
on Douglass’ published data that this material “agrees better with
Psittacotherium.” In the National Museum collection there is a speci-
men, no. 6162, from the level of and near the Silberling Quarry, which
includes parts of two canines, two complete cheek teeth, and other
72 Matthew (Pale. Mem.) places the calamodonts and stylinodonts in the Stylinodontinae and separates
the psittacotheres as a distinct subfamily.
170 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
fragments. This agrees very closely with Torrejon specimens referred
to Psittacotherium multifragum, and judged from his figures and
descriptions the same is true of Douglass’ single tooth. The generic
reference is beyond doubt, and the specific reference highly probable.”
The species is surely and the genus probably different from ?Psitta-
cotherium lobdelli Simpson, 1929, from Bear Creek, which is definitely
more advanced.
Order CARNIVORA Vicq d’Azyr, 1792
Suborder CREODONTA Cope, 1875
Matthew has repeatedly discussed and carefully defined this primi-
tive carnivore suborder, which includes all known Paleocene carni-
vores. The only serious criticism that has been made of his general
arrangement (for instance by Wortman or Osborn) is that the Mia-
cidae, being structurally ancestral to the Fissipedia, should be placed
in the latter group. This would be in accord with phylogenetic classi-
fication, but as Matthew protested and as most students must agree, a
completely phylogenetic classification is a practical impossibility.
This case is one in which departure from it seems desirable and
necessary. The Miacidae have many characters allying them with
creodonts and cutting them off from their descendants the fissipedes
and furthermore if they are removed from the Creodonta that group
ceases to exist not only as Cope defined and conceived of it but also as
a natural and practical group. Matthew’s retention of the ‘‘hori-
zontal” unit Creodonta, including the Miacidae, seems sound and is
adopted here.
In the Paleocene there are five typical groups of creodonts: Oxy-
claeninae, Arctocyoninae, and Triisodontinae (these three subfamilies
forming the Arctocyonidae), Mesonychidae, and Miacidae (Viverra-
vinae only in the Paleocene). Of these the Oxyclaeninae are far the
most primitive, without carnassial teeth and with decidedly generalized
dentition and skeleton. The Arctocyoninae are also primitive and
indeed intergrade with the Oxyclaeninae but are generally larger forms
with flat, broad, bearlike teeth. The Triisodontinae are without
shearing teeth but with peculiar blunt, heavy, and extremely simple
teeth (probably secondarily in part). The Mesonychidae, so aberrant
that they have been excluded from the Carnivora (Gregory) although
probably belonging there (Matthew), developed a pseudotriconodont
and semihomodont lower dentition and are still more strikingly
73 The Torrejon specimens show great variation, and Cope named three species, which were, however,
considered synonyms by Wortman. Matthew (Pale. Mem.) believed it possible that more than one species
occurs there but did not redefine them separately.
74 Other groups begin to appear before the nominal end of the Paleocene, but they seem to be Eocene fore-
runners, not typically Paleocene mammals.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 17
characterized by some strangely ungulatelike limb characters. The
Miacidae had typical carnassials as in fissipedes and were generally
progressive and adaptive.
All five groups are rather abundantly represented in the Torrejon
in individuals, although only the Oxyclaeninae there show much
variety in genera and species. In the present fauna the Oxyclaeninae
are also abundant and varied, relatively about as in the Torrejon,
although all the species and most of or all the genera are here different.
The Arctocyoninae are not abundant but are apparently more varied
than in the Torrejon. Triisodonts, common Torrejon fossils, are
absent in this fauna as now known, and the mesonychids are repre-
sented only by extremely rare fragments. Miacids, on the other hand,
are present and are more varied than in the Torrejon.
Family ARCTOCYONIDAE Murray, 1866 ”
This is one of the groups so largely and adequately defined and dis-
cussed in Matthew’s memoir that redefinition here is quite unneces-
sary. The genera placed in the Arctocyonidae have commonly been
distributed in the Oxyclaenidae, Triisodontidae, and Arctocyonidae
since Scott (1892) defined the first two families.
Osborn and Earle (1895) also proposed a family Chriacidae, but this
was rather a substitution for Oxyclaenidae (because they considered
Oxyclaenus, proper, as incertae sedis) than a separation from it.
Matthew (1897) provisionally proposed the use of Chriacidae for
Chriacus, ‘‘Protochriacus’” (Loxolophus), and Tricentes if, as he then
suspected, Oxyclaenus were referable to the Triisodontidae. The
latter step was not taken. Ozxyclaenus and Triisodon were eventually
placed by Matthew in the same family, Arctocyonidae, but Chriacus
was also placed there. The earlier work adumbrated a fourfold
division, with groups typified by Oxyclaenus, Chriacus, Arctocyon, and
Triisodon. Various of these were at times separated widely, but the
way in which some genera were shifted from one to another and all
sorts of combinations made shows how hard it really is to tell these
groups, or supposed groups, apart.
In his latest work, Matthew (Pale. Mem.) took the logical step of
reuniting all these genera under the oldest family name, Arctocyonidae.
It seems to be demonstrated that aJl are rather closely related and
75 I would prefer to give, and in some earlier publications have given, as author of a family the first writer
who recognized the group and gave it a name based cn a valid genus, even if he did not follow the family
form now maintained. This would make Giebel, who named the Arctocyoninae in 1855, author of the
Arctocyonidae. In fact he was, aside from quibbling, for his group Arctocyoninae was distinguished from
nonarctocyonids, not from other arctocyonids (none of which were then known) and was, as far as then possible,
the group we now call Arctocyonidae. In reality, then, Giebel is the author of this family, but the bibliog-
raphers wi!] not have it so and, of course, they are correct in the letter of the law, ifnot in a spirit of justice.
On the grounds of literal correctness and largely of feeling that the purpose of quoting authority is not to
honor but only to define, [ have abandoned my former practice. This statement applies to a number of
other groups as well as to this.
172 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
even if the supposed groups are separable, they do not all together
exceed the usual limits of a single family of carnivores.
Matthew subdivides the family into Oxyclaeninae, Chriacinae,
Arctocyoninae, and Triisodontinae. These are essentially the old
families, except that the Chriacidae of Osborn and Earle and (tenta-
tively suggested, not adopted) of Matthew was merely the Oxyclaeni-
dae with Oxyclaenus excluded, while the Chriacinae of Matthew’s
last work is based on quite a different concept and includes only
Chriacus and Deltatherium.
Despite the name of the family, its central, most varied, and most
typical group is that of the Oxyclaeninae. Separation of the Tru-
sodontinae seems justified, since these animals (not yet identified in
the present fauna) are of a peculiar adaptive type only the earliest
examples of which show close approach to oxyclaenines. The Arcto-
cyoninae form a clear-cut group if contrasted with such types as
Oxyclaenus or Chriacus, but such genera as Protogonodon, Tricentes,
Arctocyonides, or Thryptacodon, each in a different way, tend to
bridge the morphological gap and to make clear differentiation difficult
or impossible. Perhaps in the fanlike radiation of this potent and
extremely varied family several lines approached a bearlike, omniv-
orous adaptive type and the Arctocyoninae may be a partly artificial
concept uniting several of the more extreme adaptive types inde-
pendently trending in this direction. Despite this possibility, the
concept is a practical one and may well be adopted pending a better
understanding of the actual phylogeny.
The idea of separating Chriacus from the Oxyclaeninae seems less
fortunate, and it is probably impractical at present. The Arcto-
cyonidae with the Triisodontinae and Arctocyoninae removed are
a hodgepodge including many different lines each potentially or
actually as distinct as that suggested by Chriacus. These numerous
minor phyla are so intricately interrelated and most of them are so
poorly known that a good subfamily or supergeneric arrangement is
not now attainable. It does not seem helpful to separate one genus,
Chriacus, which is probably no more distinctive than each of a dozen
others. From another viewpoint the inadequacy of such an arrange-
ment is also shown by the discovery of such a type as Metachriacus,
which might roughly be characterized as ‘‘chriacine’’ in premolars
and “‘oxyclaenine” in molars. With the greatest respect for Mat-
thew’s incomparable knowledge of these faunas and clearness of
judgment it further seems to me that his collocation of Deliatherium
is based on superficial characters and that this genus differs more from
Chriacus than does any of several genera not placed in the Chriacinae.
The present fauna contains certainly six and possibly seven genera
of Arctocyonidae. Five of these were defined from this fauna and
have not definitely been recognized elsewhere. Of the Crazy Moun-
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 173
tain arctocyonids, Claenodon belongs in the Arctocyoninae. Deutero-
gonodon might be placed there or in the Oxyclaeninae, or even in the
Condylarthra. In default of better evidence and for ease of subfamily
recognition it is placed in the Arctocyoninae, which it most resembles
in adaptive characters although perhaps not phyletically close to
other members of that group.
Mimotricentes is a typical but well-differentiated oxyclaenine.
Prothryptacodon seems surely to be in the lineage of Thryptacodon,
witb which it forms a rather distinctive phylum retained in the
Oxyclaeninae, where Thryptacodon has generally been placed. Meta-
chriacus is an oxyclaenine in the broad sense. If Oxyclaeninae and
Chriacinae were separated, this genus would be incertae sedis, for it
resembles both groups. Spanoxyodon is also clearly oxyclaenine,
sensu lato, and might doubtfully be an aberrant chriacine if that
group were retained. The occurrence of Chriacus in the fauna is
possible, but not proved, and no additional evidence on the affinities
of that genus is here adduced. Coriphagus, with which the Torrejon
Mizxoclaenus is synonymous, was classified by Matthew in the Oxy-
claeninae, but I believe it to be an anisonchine, as set forth in dealing
with that group.
The members of this family are the most primitive of known carni-
vores, and, as might be expected, they are abundant in all Lower and
Middle Paleocene faunas. In the Upper Paleocene they are less
varied and common, and as far as known they died out by the end of
lower Eocene time. The Middle Paleccene forms are prototypal in
a general, structural sense, but are already too late to be ancestral
to other groups. Matthew (Pale. Mem.) has pointed out the great
interest of the family as probably including in its Lower Paleocene or,
especially (unknown), pre-Paleocene members the probable ancestry
not only of all carnivores but also of other orders, including most or
all ungulates and some others. Despite the numerous minor struc-
tural modifications, most members of the family have almost diagram-
matic tuberculo-sectorial teeth such as are believed to be primitive
for all marsupial and placental mammals. The osteological characters
of the group as a whole are also primitive for the great majority of
placental mammals, many of them for all these, but on these characters
the present materials have practically nothing to add to what is known
from the Puerco and Torrejon mammals.
Subfamily ARCTOCYONINAE Giebel, 1855
Claenodon and Deuterogonodon represent this subfamily in the
present fauna. The status of a supposed third genus, Neoclaenodon, is
discussed below. Deuterogonodon might be considered an oxyclaenine,
in view of its resemblance to Protogonodon, which Matthew so classi-
174 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
fies, but its adaptive characters, at least, are more arctocyonine and
the groups are more easily defined if it is placed here. It may not
really be a creodont.
Genus CLAENODON Scott
Claenodon Scort, 1892, p. 298.
Synonym: Neoclaenodon Gidley, 1919.
This group was studied by Dr. Gidley and the results published
(1919), his manuscript notes including no further observations. One
specimen, of considerable interest, has since been added to the Na-
tional Museum collection (by Silberling and me in 1932), and there are
several specimens in the Princeton collection that were not included
by Gidley in his publication. Dr. Gidley also studied Cope’s types
and at least two later American Museum Torrejon specimens (A. M.
nos. 16543 and 16545), but he apparently did not examine the whole
American Museum series, which includes about 50 specimens. On
this basis I am forced to adopt a broader view of the variability of
the group and to modify the generic and specific criteria used, thus
arriving at a modified systematic arrangement, which also differs from
the final conclusions of Dr. Matthew (Pale. Mem.), based on American
Museum material only.
With one exception, the Fort Union specimens were all referred by
Gidley to a new genus, Neoclaenodon. The supposed generic char-
acters as given by Gidley (1919, p. 547) may be listed and commented
on as follows:
1. “Cranial portion of skull relatively long and deep; interorbital
space apparently much narrower, and postorbital constriction longer
and more slender than in Claenodon.”’ This is based on a comparison
of two specimens, one of Claenodon ‘“‘corrugatus’”’ and one of ‘‘Neo-
claenodon”’ montanensis, as no others yet discovered show these
features. They are crushed in opposite ways, which accounts for
part of the difference in aspect. This individual of ‘‘N.”’ montanensis,
however, probably does have a slenderer and longer midcranial region,
but this is a character so variable with age, so likely to be of merely
specific value at best, and so impossible to use on a practical basis
for the separation of the fossil species that, in itself, it does not carry
generic weight.
2. “Anterior premolars, upper and lower, much reduced; in upper
jaw distinct diastemae behind P!, and between P? and P?®; the first
premolar, above and below, lies closely appressed to the canine.”’
This is in part distinctive from some specimens of C. feror, and not
from others. The influence of selecting particular specimens for
comparison is seen in the fact that Matthew (Pale. Mem.) proposed
to redefine Neoclaenodon as having the premolars unreduced {relative
to Claenodon]. In fact the whole series with its various species is
variable in these characters and varies, as far as apparent, about a
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 175
single mode. These premolar characters are certainly not generic
and probably not good specific characters.
3. ‘“Hypocone in M! and M? rudimentary.” This is a fairly clear
distinction from any Torrejon specimen known to me. The species
montanensis may be distinguished by having the hypocones of M!?
slightly smaller than the smaller variants of other known species.
If this be made a generic character, however, it would be almost the
sole character defining the genus and the genus would be monotypic,
as even Gidley’s ‘“‘Neoclaenodon”’ silberlingi probably had hypocones
proportionately as in the larger species.
4. ‘“Hypocone . . . wanting in M*; M® much reduced, suboval in
outline with relatively small metacone.”’ This again applies only to
a very limited extent to “NN.” silberlingi. Furthermore, in the
Torrejon species usually (but incorrectly) called C. protogonioides
some specimens have corrugatus-like M* and others that are, never-
theless, surely conspecific have M® almost as in “N.’’ montanensis.
O. ferox has relatively larger M*, but the hypocone is often lacking.
The character is obviously somewhat variable and when well marked
of specific, not generic, character.
5. Various skeletal characters (all repeated in the extended descrip-
tion quoted below) are also given. Here it need only be said that,
as Gidley points out, the basic structure is quite as in Claenodon.
Some characters, as the fusion of scaphoid and centrale (not, however,
considered diagnostic by Gidley) or the broad astragalus (which was
considered diagnostic), although apparently fundamental, are indi-
vidually variable in C. feror. None is more important than the
slight structural modification to be expected in smaller and larger
species of one genus.
Matthew (Pale. Mem.) accepts Neoclaenodon as probably valid
but rejects all Gidley’s characters as not being diagnostic of the
genus. He does not clearly redefine it but mentions its smaller
size, unreduced premolars, and Jack of heavily rugose enamel. ‘The
smaller size (about 25 percent) is surely not a generic character.
The supposed difference in premolar reduction is probably subjective,
as already suggested: Matthew says the premolars are less reduced
than in Claenodon, and Gidley says they are more reduced. ‘They
seem to me to be about the same, taking each supposed group as a
whole. The rugosity of the enamel is about the same proportionately
in “N.”’ montanensis as in C. ferox but is probably less in C. “‘pro-
togoniordes.”’
Matthew’s acceptance of Neoclaenodon is based on the Torrejon
species that has generally been called Claenodon protogonioides.
This name is not applicable in this way, as it belongs to a Puerco
species (probably of the genus Protogonodon), and Matthew proposes
a new name (Pale. Mem., unpublished at the time this was writ-
176 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
ten). He places the species in Neoclaenodon and bases his ideas of
Neoclaenodon on it, apparently overlooking the fact that this would
exclude its own genotype from this genus. Indeed ‘‘N.” montanensis
resembles Claenodon ferox in several points, which are differences
from the Torrejon species hitherto confused with protogonioides,
such as the more rugose enamel, the stronger and crenulated cingula,
and the shelf-like, rather than conical, protocone on P*. On this
basis the small Torrejon species might (but in my opinion should not)
be placed in a new genus, but the genus would not be Neoclaenodon.
Thus, while there are single characters on which genera might be
founded, none of these seems either well marked or highly significant,
nor are they combined in such a way as to support the separation ot
Claenodon and Neoclaenodon as proposed either by Gidley or by
Matthew. The upshot of using such characters would be to force
the erection of a genus for each well-defined species, a procedure not
useful and concordant with the really close resemblance of all members
of this group.
The species previously recognized or proposed are as follows:
Claenodon ferox (Cope, 1883). Genotype.
C. corrugatus (Cope, 1883).
C. sp. innom. (Matthew, Pale. Mem.)=“‘C. protogonioides’’, pars, of authors
(in error). [C. procyonoides (Matthew, 1937); published too late to insert through-
out the present bulletin.]
C. montanensts (Gidley, 1919). Genotype of Neoclaenodon.
C. silberlingi (Gidley, 1919).
C. latidens (Gidley, 1919).
Of these, I consider C. corrugatus as a synonym of C. feror, and
CO. silberlingi and C. latidens as of doubtful validity, one or both pos-
sibly being synonymous with C. montanensis. Another species, C.
vecordensis has been described from the present fauna.
In comparing some of the Fort Union specimens with the Torrejon
material and in considering the general nature and limits of variation
and the validity of specific distinctions in this group, it has been
necessary to restudy the Torrejon specimens. These have in the
past been referred to three species, following Cope, C. ferox, C. cor-
rugatus, and C. protogonioides. The type of C. protogonioides is from
the Puerco, and Matthew (Pale. Mem.) has shown that it belongs in
Protogonodon and that the Torrejon specimens hitherto placed there
do not belong to it but to an unnamed species (named in Pale. Mem.),
surely distinct from C. ferox or C. corrugatus.
C. corrugatus was distinguished from C. ferox by Cope as being
smaller and with the hypocone somewhat better developed. The
latter character is variable and, in the extremely slight degree in-
dicated by the types, seems to be individual. Matthew (Pale. Mem.)
considers C. corrugatus as of doubtful status but redefines it as smaller,
with less robust premolars, inner cusps less developed on P*~*, de-
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 107
cidedly smaller and slenderer canines, limb and foot bones smaller
and of slenderer proportions throughout.
I am at a loss to understand the supposed distinction of the inner
cusps of P®~* as I find no specimen identified by Matthew as C. ferox
that has those teeth. The number of specimens in which the canines
are surely associated with cheek teeth is limited, but the measurements
and ratios shown in table 37 can be taken from the collection.
TABLE 387.—Measurements of canines and molars of species of Claenodon
A.M.N.H. no. and species Cc M! G Mi & ae
= | M! Mi
Mm Mm Mm Mm
PLES (Cig olen GE (7 0) ee ee Se ee eo 12.9 TS, STU fees a a fs es 1,16
2456: (neotype: G. corrugatus) ...-.-----------=-+-=.+=2- 8.3 10.5 7.8 12.5 0.79 0. 62
165455 (Ola COnUy QUES) == senna en enon foe Seen ee 11.2 TORO ea See 1,12
TG OIE Ga CR a Rae TE) ae a os Oe Se eS eee eee 10.0 11308 See 0.91
MMs (FOL LG afeTOr) 2 v= Le eee ee Fe a Al Wn ase oot 10. 2 1ORGEI= S22 z8 0. 96
BAGO A EOtn Ca CONT QLLS) a2 = ee eo ee eee ee Meee ales lo ae 8.8 1152) \|S22e24=2 0. 73
|
1 Not identified by Matthew, Pale. Mem., earlier references.
2 Doubtfully referred by Matthew, Pale. Mem.
No. 3271, with the smallest cheek teeth, has the largest canine
among the lower jaws, and no. 2456, with the largest cheek teeth
among the lower jaws, has the smallest canine. Indeed among the
lower jaws the relative canine size varies inversely with the cheek-
tooth size, the exact opposite of the bypothesis on which the species
are separated. Among the upper jaws the largest cheek teeth are
associated with the relatively largest canine, medium-sized cheek
teeth with the relatively smallest canine, and the smallest cheek teeth
with relatively middle-sized (but in ratio nearer the relatively largest)
canine. The samples are too small for extended statistical study,
but it is quite obvious that the smaller individuals are not charac-
terized by relatively small canines, and hence that the supposed
specific distinction in this character is invalid. Beyond that no
regular correlation of gross size, or cheek-tooth size, with relative
canine size is suggested or possible on these data. It is suggested
that canine size is extremely variable and that both large and small
cheek teeth may be associated with both relatively large and small
canines. There is perhaps a sexual distinction in relative canine size
in addition to or instead of in absolute cheek-tooth size, but this is a
hypothesis that the data are inadequate to test.
The smaller premolars and slenderer skeleton supposedly distinctive
of OC. corrugatus cannot be more exactly checked, and the results are
similar: they are smaller, because they belong to smaller individuals,
but there is no apparent correlation of relatively smaller premolars
or relatively slenderer limbs with the smaller individuals.
178 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
The distinction thus is reduced to a matter of size. To judge this
I have taken a single dimension, the length of M2, because it seems to
be a valid indication of cheek-tooth or gross individual size and can
be measured in a relatively large number of individuals. Other
dimensions give similar results and all need not be published here.
There are in all 24 individuals of the genus Claenodon from the Torre-
jon in the American Museum collection in which the length of M2
can be measured. The small species hitherto confused with C. pro-
togonioides is obviously distinct, and the following data apply only
to the C. ferox—corrugatus group.
Calculated probable -Neotype,C. corrugatus.
position of type, \
Cc corrugatus.
Ty pe, C. Ferox.
Type,C. n.sp. Matthew.
ee NO 'G 2 e-oi
Number of tndividua/s.
7.8 63 88 9.3 9.8 10.3 10.8 11.3 11.8 12.3 12.8 13.313.8 14.3
FIGURE 35.—Histogram of length of M2 of Claenodon from the Torrejon of New Mexico in the American
Museum.
The statistical data on the length of M, of the group are as follows:
INuntbertintsampletecssss 52) a eee eee 18
Observed range. tas) aS) shee Is DA cee Io "139
IN Detar = 2a dat ot CP PAP eS eee, eh Seep DEC 12. 68+ 0. 25
Standard deviation.--4 'e = an eee eee Sere 1.06+ 0.18
C@ochicient-of vanlatlons== 622s. 6s Cee see 8 3.+ 14
Contrary to some (e.g., Klihn) of the few paleontological workers
who have used any statistical data but the most elementary, I can-
not agree that the extent of variation (‘‘Variationsbreite’’), in this
case 2.4 mm (11.5 to 13.9), has any valuable connotation, being so
dependent on accidents of sampling that the probable error is enormous.
The same fundamental idea is more correctly conveyed by the stand-
ard deviation. The above data are calculated from raw measure-
ments to 0.1 mm, but in the histogram (fig. 35) these are grouped in
units 0.5 mm wide, because of the small size of the sample and because
0.1 is certainly too refined a measurement and below the limits of
mechanical error and errors due to crushing of the specimens, etc.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 179
The only deflection in the frequency curve is in the 12.05-12.55 group,
and this is not significant. By actual calculation, which need not be
given here, a deflection at this point would have to be of at least 3 to
have any probable significance, and this deflection is in fact only of 1.
The mean, the median, and the mode almost exactly coincide.
The distribution thus indicates a unimodal, unskewed curve, and
provides no warrant for splitting into two groups, or species, on the
basis of size (or of this dimension, which is sufficiently closely cor-
related with size).
The actual positions of the types are indicated on the histogram.
The neotype of C. corrugatus, although not elsewhere formally so
designated, is such essentially as Matthew (Pale. Mem.) largely bases
his redefinition of the species on it. The type of C. corrugatus has no
M,, but it must have measured about 12.0 mm in this dimension, caleu-
lated from the ratios of associated M? and M, in surely conspecific
individuals of about the same size. Mz, of the neotype of C. cor-
rugatus is 12.4 mm in length and of the type of C. feror 13.4 mm.”
The deviations of these three specimens are: C. feror, type, +0.72;
C. corrugatus, plesiotype, —0.28; C. corrugatus, type, calculated,
—0.68. All these deviations are considerably less than the standard
deviation. There is no reason or warrant for placing these individuals
in different species on the basis of size.”
The coefficient of variation, 8.34, is high and indicates a species of
considerable variability in size, but there are many cases of dimen-
sions of single species, and even of subspecies or pure races, with
equally high variability, or higher, and this figure does not in itself
suggest that two species, inseparable on these data, may be present.
These data do not prove that two species are not present: Such
proof of a negative is practically impossible, and the burden of proof
is always to be considered as required from the positive side. They
do show that in this sample it is impossible to distinguish two size
groups (and hence two species distinguished by size differences), that
the distribution is not inconsistent in modality, variability, ete., with
a single species, and adding considerations somewhat beyond purely
statistical treatment, that if two species were present they would very
probably not correspond with those now recognized.
There are no other variates or attributes, so far as I can observe,
that do permit any differentiation of this group into two or more
species. The supposed species occur together, at the same horizon
and localities, and in approximately equal numbers.”
76 It is crushed and spread a little, but this can be exactly allowed for.
71 It may also be noted that on the purely hypothetical and extremely improbable supposition that two
species were present and that their size limit corresponded with the deflection in the frequency curve given,
the neotype of C. corrugatus would belong with C. feror and the type of C. corrugatus wculd be on the beund-
ary between the two groups.
78 This, of course, depends on individual identifications, but if these were to be based on any rational
size distinction the grouping would have to be into two approximately equal groups.
180 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
In short, C. corrugatus and C. ferox are not distinguishable on any
correct factual basis derived from the known specimens, and they
must be considered synonymous, the name C. ferox being retained for
the species. The value of the coefficient of variation may be taken
as indicative of the degree of variability to be expected in the same or
analogous dimensions in species of this genus.
The relationships of the genus Claenodon as a whole have been
widely discussed and are summed up so thoroughly by Matthew
(Pale. Mem.) that no details need be given here. It is a typical
arctocyonid, very close to Arctocyon itself, and in its larger species,
at least, forerunner of the lower Eocene Anacodon, after which the
line evidently became extinct. Relationship with the bears has often
been suggested and was favored by Dr. Gidley, but it is almost cer-
tainly erroneous. There is very little question that bears developed
from dogs during the Middle or Later Tertiary and that the limited
convergence to them shown by Claenodon involves habitus characters
only and denotes a convergence in food and other habits, but not
any special affinity.
FIGURE 36.—Claenodon feror (Cope), tentatively referred specimens from the Melville (Fort Union No. 3):
a, U.S.N.M. no. 6156, left M2; 6, Princeton Univ. no. 13755, right Mi, probably from Loc. 44; c, same data
as 6, left Ma-3 and heel of My; d, same data as 6, right M!-%, M! broken; e, Princeton Univ. no. 13756, left
M!-3, M! broken, probably from Loc. 49. All natural size.
CLAENODON FEROX (Cope, 1883)
FIGuRE 36
U.S.N.M. no. 6156, a left”? M, and some other fragments, from
well up in Fort Union No. 3, was tentatively referred by Gidley (1919,
pp. 545-547) to Claenodon ferox, with the reservation that better
material might prove that a new species is represented. Gidley noted
several distinctions from characteristic C. ferox of the Torrejon but
suggested that all could be due to individual variation, except, perhaps,
the fact that in the Montana specimen the talonid is narrower than
the trigonid. This, however, is also within the range of variation of C.
79 Gidley, 1919, p. 545, says “‘right’’, obviously a lapsus calami.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 181
Jeror, and there are Torrejon specimens practically identical with that
from Montana in size and structure. The specimen probably does
represent C. ferox, but the single tooth is inadequate for certain deter-
mination. Thesame statement applies to no. 9651, an isolated left P‘,
from Loc. 53.
There are several Princeton specimens of Claenodon from their
cluster of localities in Fort Union No. 3 near the center of the field.
These all appear to represent one species, with considerable variation
but not beyond that usual for this group. Morphologically they are
within the limits of the C. ferox group and cannot be separated from
that species.
CLAENODON MONTANENSIS (Gidley)
Ficures 37-39
Neoclaenodon montanensis GIDLEY, 1919, p. 547.
Type.—U.S.N.M. no. 8362, much of the skull and jaws with most of
the dentition, parts of fore and hind limbs, and other fragments.
Collected by A. C. Silberling.
Horizon and locality —Gidley Quarry, Fort Union, Middle Paleo-
cene horizon, Sweetgrass County, Mont.
Diagnosis —Gidley (1919, p. 550): “About one-fifth smaller than
Claenodon ferox and C. corrugatus, slightly larger than C. protogoni-
oides (Cope); face relatively short, rostrum deep; brain-case very
small and elongate; postorbital constriction long and slender; posterior
root of zygoma depressed below the basioccipital plane (probably a
primitive character and of much more than species significance),
giving a decidedly arched contour to the main portion of the skull
viewed from the side; anterior border of orbit directly above anterior
boundary of m?’; infraorbital foramen directly above middle of p’*;
the large, moderately recurved, slightly compressed canines with
root-portion much swollen and in contour difficultly distinguishable
from the crown into which it merges without any deviation in outline;
1st premolar, upper and lower, single-rooted, relatively large (com-
pared with p?) and closely appressed to the canine; p* and p‘ trian-
cular, three-rooted, p* with incipient protocone; upper m* * suboval
in outline, much reduced with low external cusps, the metacone
relatively small and inwardly placed; p3; and p, with small, narrow,
single-cusped heels; lower jaw relatively thin and deep with the lower
border of its anterior half but slightly curved.
“MEASUREMENTS
Length of upper dental series, C to M3 (estimated) -----.---------- 63.1 mm.
eng DN stO UMS eo = see aA ee et TE 37.6 mm.
PPeirert heen (CSt Med GEC aegis siete Nene oe ee ee ee a a ee ee 7.3 mm.
8 The original has ‘‘m2”’, an obvious misprint.—G. G.S.
182 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Warelthpse. 2 cel te eh es oa Be ee ee eee 7.5 mm.
hengthetale oti 2 joe coe ee ee SI ee ees a ee 9.4 mm.
AWA I Galena Gkeempstae etn te ett AUS Oe copies a ove mie SIAR eer re ta Ne Be ee oe 10.0 mm.
j SS ea FW 0 0k I ape FP Sie Sa gS a ie ei Se ee eee Oe eh er 5.5 mm.
AWailch Gy sna Guerre See een ee cpa eR he ee ee eae 2 ee 9.3 mm.
Uength- ot lower dentalvceries Cito mau Sass Se ee eee 65.0 mm.
Length im) to migeee tins. Lou Reet oak, Beeb Iss. LS Les. See 28.5 mm.
Lengthy) 24.842 455 edt atone ce eee LE) foe ot ee ea 9.4 mm.
WiGGlNaige ae hy be se ee eee ee Se ye eee 7.5 mm.
Thenetias era fos oe re ee ee oe Ree ee 9.9 mm.
LAGU Plaga spans aI yt lse teat Capa ad nail [ie al ei eae ea raat ted We Eas EB 6.5 mm.
Depth oPyaw ats. 2 Nee NE SS eae eee poe eee ee 21.5 mm.
Depthrof jaw -atipe:s?- 4: 294.2542 82 Ssh ee ee 18.2 mm.
Total basal Jength.of skullk(estimated) 72025 Se sessa ye = eee 155.0 mm.
Width of skull across orbital region, including zygomas (estimated)__ 65.0 mm.
‘“Hyen in our present knowledge of the claenodont group it is diffi-
cult to determine the limits of individual variation and species char-
acters; and it is quite probable that some of those here stated have a
much wider significance than I have given them, while others may have
less importance. This statement applies equally to the following
more detailed description of the type specimen.
“The skull is not greatly specialized but shows the following char-
acteristic modifications: glenoid fossae situated forward in position as
in the Miacidae; sagittal crest high and prominent (primitively cor-
related with the small brain, and the large canines with which were
doubtless associated heavy temporal muscles), occipital crest but little
expanded; nasals long, slightly widening forward and overlapped by a
considerable portion of the maxillary in the normal creodont-carnivore
way; posterior root of zygoma prominent with roof of glenoid fossae
depressed below the level of basisphenoid plane as in the bears; rela-
tive position and arrangement of cranial foramina, also as in the
Ursidae, that is, the optic foramen is placed well forward of the ante-
rior sphenoidal fissure which lies close to the foramen rotundum, with
the anterior opening of the alisphenoid canal just below them; the
ethmoid foramen lies nearly above the optic foramen and well behind
the postorbital process (an important character, as the position of this
foramen marks the posterior border of the cribriform plate of the
ethmoid); foramen ovale, and posterior opening of alisphenoid canal
connected by a groove or depression which is separated from the
basisphenoid plate by a prominent ridge of the alisphenoid.”’
Discussion.—Dr. Gidley also well described and figured the various
known limb elements of this species. As already suggested, most of
the distinctions noted by him were based on comparison with a single
specimen of Claenodon ferox, and they disappear or seem of very little
importance when more material is brought into the comparison. The
proportionate widths of radial facets on scaphoid and lunar are 5.3:8.1,
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 183
or 0.65 (almost exactly two-thirds, as stated by Gidley), and in one
specimen of C. ferox (that with which Gidley made comparisons) this
ratio is 10.1:15.4, or 0.66, so that the different size, preservation, and
to a slight degree proportions evidently misled his eye when he sup-
posed the ratio to be significantly smaller in C. montanensis. The
FIGURE 37.—Claenodon montanensis (Gidley), U.S.N.M. no. 8362, skull and jaws, left side. Three-fourths
natural size. (After Gidley, 1919, fig. 5.)
Des ep
fda" yf
Y ol ij
EEL
Ye ln Yr
< Y
Uy :
_ Nf lage
YY A, Write. ‘ , Y AL
HT Yi : ED:
LT
YY, Uh ; S S weX fA
ee ye
: \ %, pss: oa Z Za
Wijjsty, ~~
CD
= tl
VID >
My, PLL
EH jib
FIGURE 38.—Claenodon montanensis (Gidley), U.S.N.M. no. 8362, skull, palatal view. Three-fourths
natural size. (After Gidley, 1919, fig. 6.)
ratio of total widths is 0.47, or about half, as stated by Gidley, in
C. montanensis type, and 0.46 in the specimen of C. feror, which again
is a wholly insignificant difference. Computation of the exact figures
also shows Gidley’s impression that the vertical depths of the anterior
faces of these bones are relatively less than in C. ferox to be mistaken.
They are in fact slightly, but not significantly, greater than in this
specimen of C. feror.
119212—37——18
184 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
In Gidley’s description of the caleaneum (1919, p. 552), ‘‘tibial face”
is probably a misprint for “fibular facet.”” The type calcaneum is
somewhat damaged in this region. A specimen collected after Dr.
Gidley’s paper was published shows that in C. montanensis the fibular
facet on the caleaneum is relatively quite as well developed as in
CO. feror. His statement, ‘cuboid with facet for the astragalus,
navicular and ectocuneiform arranged horizontally, nearly parallel and
merging into each other” also appears to involve a misprint or lapsus,
since it is inconsistent with his accurate figures and is either not clear
or not correct. As his figures show, the astragalar facet is at an angle
of nearly 90° to the navicular facet, and the latter and the ectocunei-
FIGURE 39.—Claenodon montanensis (Gidley), U.S.N.M. no. 8362, foot bones: a, Lunar and scaphoid, dorsal
view; b, part of tarsus, dorsal view; c, parts of the three median digits of pes, dorsal view. Natural size.
(After Gidley, 1919, figs. 7 and 8.)
form facet are approximately in the same vertical plane. Comparison
of several specimens of C. ferox does not confirm the supposed differ-
ence in this species in the separation and different outline of the two
last mentioned facets on the cuboid. These facets are much less
definite in the available specimens of C. ferox *! than in C. montanensis,
but differ little in outline.
Dr. Gidley’s important conclusion that the present limb bones are
closely similar to those of Claenodon ferox is certainly correct and is
only emphasized by these slight corrections of details. The C. mon-
tanensis material is little over half of the size of that of C. ferox, and
it differs in details of proportion, strength of processes, or rugosities,
& The artist has made their outline far too distinct in Gidley, 1919, pl. 28, fig. 2a.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 185
such as are normally specific functions of size, but not in any essential
structure.
As already suggested, Dr. Gidley’s comparison with Ursus seems.
to me to be beside the point and to involve no features not to be
expected by convergence in heavily built plantigrades not more closely
related than as members of wholly different groups of the same order.
The species is surely distinct from C. ferox, being excluded from
that group by the smaller size, reduced hypocone of M!, and reduced:
size and more transverse proportions of M*. (Some of the other
characters given by Gidley are not of probable specific value.) The
size is within the probable range of the small unnamed Torrejon
species. For instance, the length of M, is 9.2 in the largest Torrejon
specimen of the small species and 9.4 in the type of C. montanensis.
The size distribution doubtless overlaps, but were a larger series
available it is probable that the mean for the Fort Union specimens
would be found to be significantly greater. The reduction of the
posterior part of M* is also within the extreme limit of variability of
the Torrejon species but probably is a specific character varying about
a different, but not widely separate, mode. The somewhat smaller
hypocones of M'~? and the less conical protocone of P* seem to be
beyond the limits of the Torrejon specimens and thus still better
specific characters, on present data. Possibly correlated with the
differences in P* is the somewhat narrower, more distinctly unicuspid
character of P,, also apparently a good specific character.®”
U.S.N.M. no. 9634 is an isolated M, from the Gidley Quarry,
measuring 9.4 by 6.5 mm and referable to this species with little
doubt. No. 6159, from Loc. 52," includes right and left M>, appar-
ently associated, and other fragments, also referable to C. montanensis.
CLAENODON SILBERLINGI (Gidley)
Fiacure 40
Neoclaenodon silberlingi G1IDLEY, 1919, p. 552.
Type—U.S.N.M. no. 8363, part of left®* maxilla with P?-M? and
alveoli for canine and P!-*. Collected by Dr. J. W. Gidley.
Horizon and locality —Gidley Quarry, Fort Union, Middle Paleo-
cene horizon, Sweetgrass County, Mont.
Diagnosis —Gidley (1919, p. 553): “A slightly smaller species than
N. montanensis from which it differs as follows: cusps of all the molars
seemingly! more depressed; m* and pm’s*:* somewhat less reduced
82 These, of course, substantiate the validity of the still unpublished Torrejon species, rather than of C.
montanensis, which has priority and is surely distinct from any species previously named.
8 Labeled ‘‘Gidley Qu.’ (Recorded Loc. ‘No. 52’=Loe. No. 4).’’ Loc. 52 is very near the Gidley Quarry
and about 50 feet lower stratigraphically. The difference does not appear to have any importance, but
the localities are not exactly the same.
§ “Right” in the original designation of type (Gidley, 1919, p. 552) is a lapsus.
“1 Though found in its original bed, the enamel of all the teeth is considerably damaged through weather-
ing or leaching by surface water which had reached the specimen through cracks in the matrix.”
186 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
although more reduced than in Claenodon: all the cheek teeth, ex-
cept p’*, relatively wider; distance between p* and the canine relatively
greater indicating a somewhat more elongate face; infraorbital foramen
approaching nearer to the alveolar border above p’.
“This species in size approximates C. protogonioides (Cope) but is
apparently clearly distinguishable from the Puerco species by the
much greater reduction and more oval contour of m*, and in the
relatively wider proportion of all the cheek teeth.
“MEASUREMENTS OF N. silberlingi
citoymts ts bocce tsodie set 254 ee eee ie a ee ssa 60.0 mm
DORMS sac om a i ea ee 34.5 mm
TMstO Meee ea ee ee ae ee eee ee Soe as see eos 21.4 mm
mblengthess 22. sacs ost et eas cana nas + Rene aee cone Sees 7.0 mm.
ATE WICC Bon ose eae Se eee Re SE eed ees ee PEs eee 8.8 mm.
meen gties, 2602. 4. ts hee eee Be ee eae ane 7.4 mm.
metwidthestne yo8 sel Se Sh soa eh ese Sake te es ese S 11.5 mm.
any wen Pheer 2S. ok SE a ae nS bor eee oes ae ON A Se 5.0 mm,
MieaWiGl this see oe ee oe eee ee eee ee re iora ae 9.0 mm.
5.0 mm
5.5 mm
7.5 mm,”
FIGURE 40,—Claenodon silberlingi (Gidley), U.S.N.M. no. 8363, left upper jaw: a, Crown view; 0, external
view. Natural size. (After Gidley, 1919, fig. 9.)
Discussion —Allusion to ‘‘C. protogonioides” implies comparison
rather with the unnamed Torrejon species of Claenodon than with
the different Puerco species to which the name properly applies.
The type of this species is so poor, the cusp structure being very
much obscured and in part destroyed by corrosion and breakage, that
it cannot surely be distinguished from the small Torrejon species, on
one hand, or from C. montanensis, on the other, although these two
are distinct from each other.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 187
The relative size and contour of M? are, in fact, well within the
range of variation of the Torrejon species, and the teeth are not
significantly more transverse. The size is large for that species but
not beyond its presumable range and hence of doubtful significance.
It is impossible to give good clear diagnoses separating the two,
although it is my opinion that they are probably distinct.
It is, on the other hand, probable that C. silberlingt is synonymous
with C. montanensis (adding to the probability that it is not the same
as the Torrejon species). The size is about the same, and both types
are from one quarry. Mlis a little shorter in C. silberlingi, and some-
what more transverse, but these are doubtfully real, since the speci-
men is so poorly preserved, and if real are not marked enough to prove
any taxonomic distinction. M?® is definitely larger than in C. mon-
tanensis. The ratio of their lengths, the dimension in which they
differ most, is 1.10. In Torrejon specimens of the C. feror group the
variation in absolute dimensions is much greater than this, and the
size of M’ relative to M! or M? also varies quite as much as the differ-
ence between C. silberlingi and C. montanensis, although this is a more
constant figure.
The distance between P? and the canine is almost exactly as in C.
montanensis. In calling it “Telatively greater’, Gidley must have
meant relative to the length of M!, but as the other tooth dimensions
are as great as in C. montanensis this is simply to repeat that the
length of M! is relatively small and is not a character of the diastema.
M!*? may have had larger hypocones than in C. montanensis, but this
is almost hypothetical, and the protocone of P* may have been stronger,
also rather dubious.
I retain the name tentatively, on these very doubtful characters,
but believe that the species will probably prove to be invalid.
CLAENODON LATIDENS (Gidley)
Ficure 41
? Neoclaenodon latidens GipuLEyY, 1919, p. 554.
Type-—U.S.N.M. no. 8388, right lower jaw with M,-3, a small
fragment of M,, and the broken lower part of the ramus from the
canine alveolus to the angle. Collected by Dr. J. W. Gidley.
Horizon and locality. Gidley Quarry, Fort Union, Middle Paleocene
horizon, Sweetgrass County, Mont.
Diagnosis.—Gidley (1919, pp. 554-555): “Size approximately that
of N. montanensis, but with decidedly wider molars; jaw relatively
longer, much straighter, and more slender. Since the upper dentition
of N. latidens and the lower dentition of N. silberlingi are not known,
these species can not now be compared, but the difference in size
seems sufficient to distinguish them.
188 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
“MEASUREMENTS
Tengthiof mpreLo eas 5 Le Se ee 2 eee Se Soe cce ea eeees 9.7 mm.
WWaACthiOt ingot ee Sa ee ee ea NE eee oe 8.4 mm.
Wengiheiigss Goes eee ee es Ne ee ees) Sele ee eee 9.6 mm.
Wiidlithrofarnises=, tate rep tees et eens BITE N ble SCRE Sere) Yank ee ea ee 7.6 mam.
Depthvol jaweal Mee = ase ee ee ee eee 16.0 mm.
“Unfortunately, as in the type of N. silberlingi, the enamel of the
inolars has been considerably damaged through weathering or leach-
ing by surface water, which somewhat obscures the detailed structure.
“The generic reference is provisional, since certain features, as the
straight and more slender proportions of the jaw and relatively greater
width of the lower molars, so sharply distinguish N. latidens from all
other species of this genus or of Claenodon. They suggest that its
affinity to the group to which I here assign it may be, after all, not very
close. More complete and better preserved material may, therefore,
necessitate placing it in a distinct genus.”’
WO ES
FIGURE 41.—Claenodon latidens (Gidley), U.S.N.M. no. 8388, with parts in outline probably adapted from
other species of Claenodon, right lower jaw: a, Crown view; 6,external view. Naturalsize. (After Gidley,
1919, fig. 10.)
Discussion.—The apparent differences from C. montanensis in the
suape of the mandibular ramus are, in my opinion, illusory and due to
the different preservation of the two specimens. ‘The jaws appear to
have been almost identical or at least well within the possible range for
asingle species. So far as available material goes, the species depends
wholly on the notably wider M,_3._ That thisis of specific value is not
certain, especially as the size is otherwise that of C. montanensis and
both are from the same quarry, but the species may be tentatively
retained. Isee no reason to suspect that a new genus is represented.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 189
CLAENODON VECORDENSIS Simpson
Figure 42
Claenodon vecordensis Stimpson, 1935d, p. 232.
Type.—U.S.N.M. no. 13781, left M?-3. Collected by A. C. Silber-
ling and G. G. Simpson, 1932.
Horizon and locality —Loc. 9, 300 feet above the base of Fort Union
No. 1, Crazy Mountain Field, Mont.
Diagnosis —M? similar to that of C. silberlingi in outline but 10-20
percent larger and somewhat more transverse; hypocone vestigial,
strong crenulated internal cingulum. Mj? relatively as large as in
C. ferox and similar in structure except for smaller metacone and more
evenly rounded external border; vestigial hypocone present.
Discussion.—This species is smaller than the smallest known variants
of C. feror, has a smaller hypocone on M?, and the contours of M?
and M? are different and beyond the known range of variation of that
species. C. silberlingi is somewhat smaller and has different tooth
proportions. M?* is much larger and less transverse than in C. mon-
tanensis and has the posterior part better developed. The small
unnamed Torrejon species is much smaller and has less wrinkled
enamel, and the internal cingulum is feebler or absent.
FIGURE 42.—Claenodon FIGURE 43.—? Claenodon
vecordensis Simpson, sp., U.S.N.M. no. 6158,
U.S.N.M. no. 13781, left left Mi, crown view.
M?-3, crown view. Nat- Natural size.
ural size.
It is unfortunate that another poorly known species must be added
to this genus, already burdened with several species of doubtful status,
but the present specimen is identifiable and surely cannot enter into
any species previously established so far as their range of variation is
known or can be fairly inferred. It is, furthermore, from a very dif-
ferent geological horizon from the other Fort Union claenodonts and
one from which little material has been obtained, so that its strati-
graphic importance also necessitates some convenient designation for it.
Measurements: Length M?, 9.0; width M?, 13.5; length M°, 6.7;
width M?, 10.0.
?CLAENODON species
FIGURE 43
U.S.N.M. no. 6158, from the Gidley Quarry, is a left lower jaw frag-
went with M,, Among Dr. Gidley’s notes are two sheets devoted to a
190 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
description of this specimen, in which it is placed in a new species.
Apparently it was at first placed in Claenodon with a query, and later
the generic name was erased and another, which appears to be new,
substituted, but no corresponding change was made in the description,
and the genus was not defined. I do not believe this to be adequate
for the definition of either genus or species and feel obliged to suppress
these manuscript names. The specimen is aberrant (with respect to
species of Claenodon) in several details, but their significance cannot be
judged and comparative Fort Union material is too scanty for good
diagnosis. It is, for instance, entirely possible that this belongs to
Claenodon latidens.®
Genus DEUTEROGONODON Simpson
Deuterogonodon Simpson, 1935d, p. 232.
Type.—D. montanus (Gidley).
Distribution.—Middle Paleocene, Fort Union, Montana.
Diagnosis.—Dentition basically arctocyonid in type, and resembling
Protogonodon and Claenodon. Small, distinct, cingulum hypocone on
M?-3 (at least), cingula almost completely circling these teeth. Small
but well-defined mesostyle present. Parastyle of M* a distinct cusp,
crowning a lobe projecting strongly externally. Lower molars with
trigonid only slightly higher than talonid, metaconid smaller than but
as high as protoconid. Paraconid very small but distinct, subconical,
on slope of metaconid directly anterior to its apex. Talonid basin
open, crescentic lophid continuous but crest differentiated into bypo-
conid, hypoconulid, and entoconid, progressively smaller in that order.
Enamel wrinkled, but all cusps clear-cut and little or no tendency to
form crenulations or accessory cuspules.
Discussion.—This seems to be a very distinctive genus, at once
distinguished from any similar form by the presence of a mesostyle.
The combination of the other characters given is equally distinctive,
although individually they are less so. The genus could be a deriva-
tive of Protogonodon, although it is too incompletely known and too
distinctive to establish this as a definite theory. I know of no Torre-
jon genus that compares more closely than the probably related but
manifestly distinct Claenodon, and none of the lower Kocene arctocyo-
nids could be derived from Deuterogonodon. The possibility that
Phenacodus was derived not from Tetraclaenodon, as commonly sup-
posed, but from Protogonodon by way of a form something like Deu-
terogonodon is worthy of consideration but cannot be very seriously
8 Dr. Gidley may have had the same idea, and his manuscript is perhaps older than the publication of
1919. The specimen was collected before the type of C. latidens and was obviously in Dr. Gidley’s hands
when he wrote his claenodont paper, so that its omission may well be due to his having decided that the
specimen did not warrant a new name.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 191
upheld on present evidence. Aside from the presence of a mesostyle,
Deuterogonodon is much less like Phenacodus than is Tetraclaenodon.®
Dr. Gidley’s manuscript notes include two drafts of a description of
the type of this genus, in both of which it is referred to Protogonodon.
On one, however, almost surely the second, the words ‘‘new genus”
have later been written under ‘‘Protogonodon.’”’ Gidley thus came to
recognize the clear-cut distinction of this genus from Protogonodon, but
his notes do not contain any generic diagnosis
or new generic name, and I have been forced to
supply these.
DEUTEROGONODON MONTANUS (Gidley)
Ficure 44
Deuterogonodon montanus (GIDLEY) Simpson, 1935d, p. 233.
Type—U.S.N.M. no. 6160, part of right maxilla
with a fragment of M!, M? lacking the paracone
and parastyle, and M* complete, with a left lower
jaw fragment, possibly of the same individual and
almost surely of the same species, with the talonid
of M, and most of M,. If these should prove not
to be one individual, the upper teeth constitute
the type, and the lower teeth are a paratype.
Collected by A. C. Silberling.
Paratype-—U.S.N.M. no. 6161, isolated right Mo.
Horizon and locality —All material is from Loe.
25, about 300 feet above the base of Fort Union
No. 2, Sweetgrass County, Mont. FIGURE 44.— Deuterogonodon
Diagnosis.—Gidley: ‘‘SSomewhat larger than P, anus (Gidley): a, U.S.
N.M. no. 6160, right M?-3,
[Protogonodon] pentacus (Cope).’’ *” crown view; 6, U.S.N.M.
Simpson: Sole known species of the genus as 7° 6161, right Ms, crown
view; 6’, same, internal view.
defined above. Natural size.
Measurements are as follows:
IMe2tinediantwid tinct ty Wes eter ne dete hh ee 14.6
Ne Neng thie. * sy hee ee es 2 ess he eee: See ee: Be 10
Mies (paratype)! wach hes Sel elo pe eee re ae ee 10.5
IMGs (Araby pe) tenet ne 2 a ao See ro ee 12. 6
8 A new species of Profogonodon from the Puerco, which I have described in a note published as a
supplement to Matthew’s Paleocene Memoir, suggests that within the genus Protogonodon there was a
tendency to develop along two different lines, one leading (or related and collateral) to Telraclaenodon and
one more definitely creodont and Claenodon-like. If derived from Protogonodon, Deuterogonodon probably
arose from a species of the latter, rather than of the former, group.
87 I quote only enough of Dr. Gidley’s diagnosis to establish his authorship of the species. The rest of
the diagnosis compares with the Puerco species of Protogonodon and is hence rather generic than specific,
and among the few characters given I cannot agree as to the reality or value of some, and others seem to
involve slips of the pen that I cannot correct with any certainty that Dr. Gidley’s thought is being followed.
The rough manuscript was far from completion.
192 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
?DEUTEROGONODON species
U.S.N.M. no. 9653 includes part of a left maxilla with P*-M?
and part of a right mandible with the heel of M3. All the teeth are
incomplete and much battered, and none is directly comparable with
the types of D. montanus, so that pertinence to that genus and species
cannot be established but is probable, at least as far as generic
identity. The principal characters exhibited are that P* has a strong
conical protocone, somewhat smaller than the external cusp or cusps,
and that in the talonid of M; the three cusps, especially the entoconid,
are more distinctly separated than in M,-» of the type of D. montanus.
These specimens are from Loc. 18, the horizon of which is in doubt
but is higher than that of the types of D. montanus and in Fort
Union No. 3.
There are likewise a few tooth and limb fragments, from the type
locality, that probably belong to this genus but are of no particular
value at present.
Subfamily OXYCLAENINAE Matthew, 1937 (Oxyclaenidae Scott, 1892)
The oxyclaenine genera of this fauna, Metachriacus, Mimotricentes,
Spanozyodon, Prothryptacodon, and (somewhat doubtfully) Chriacus,
belong with several other Paleocene genera in a very confusing com-
plex. The size ranges of their species do not differ greatly, and their
morphology is markedly stereotyped in general pattern. Within the
limits of this general type, however, they seem to ring almost every
possible change in combinations of detail, so that they are difficult
to distinguish yet are amazingly varied in minutiae and cannot be
grouped into one or a few broad but natural genera. The variations
involve, among other features:
1. Placing of the canine (from vertical in Tricentes, etc., to strongly
procumbent in Prothryptacodon, etc.).
2. Number and crowding of premolars and associated develop-
ment of diastemata, varying from such types as Metachriacus to
Spanoxyodon.
3. Molarization of Py, from a wholly premolariform type, as in
Tricentes (and several other genera) to a submolariform condition as
in Spanoxyodon.
4. Reduction of the paraconid, from strong and distinct (e. g.,
Deltatherium) to almost indistinguishable (e. g., Mo-3 of Metaehriacus).
5. Placing of the paraconids, from almost strictly internal (e. g.,
Mimotricentes) to almost strictly median (e. g., Tricentes).
6. Elevation of the trigonids and their shearing character, from
high and strongly shearing (e. g., Chriacus) to low and bunodont
(e. g., Tricentes).
8 Dr. Gidley labeled them as of the same species.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT.
193
7. Proliferation of accessory cuspules, from practically nil (e. g.,
Chriacus) to considerable and distantly approaching the multicuspid
‘“arctocyonines” (e. g., Metachriacus).
8. Development of hypocones on upper molars from practically
nil (e. g., Deltatherium) to pronounced (e. g., Chriacus).
Other characters, known in fewer genera, also seen to be highly
distinctive, such as the molarization of upper premolars, width of
external upper molar shelf, shape of paracone and metacone, and
many other characters.
Table 38 contrasts the genera of this complex that occur in this
fauna, and those most likely to be confused with them, as regards
these characters.
TABLE 38.—Comparison of dentition characters in six genera of Oxyclaeninae
a
Genus Canine Pi-4 Diastemata Ps
GChriacus_ 2. .-.-- Moderately procum- | Present..__| Slight or none...--_- Slender, with small, dis-
bent. tinct metaconid.
Metachriacus-_--_- Ci Chiiacusiesa oe ae |e G022222= ChiGhriacue-2222_- Cf. Chriacus.
Dricentes--=--=—-- Crown vertical__...___- P; absent__} Short, C-P:__-----.- Stouter, no metaconid.
Mimotricentes....| Cf. Tricentes__..------- Presentes.-| sNones =. == 2-2-2 =e Cf. Tricentes.
Spanoxryodon.--_-- Cin Chrideus 2-222 P;-2 absent_| Long, C-P3._.__---- With metaconid larger
than in Chriacus.
Prothryptacodon__| Strongly procumbent, | Present_.__| Very slight, around | Slender, metaconid
root extending be- Piva. barely incipient or
neath premolars. absent.
|
rr ————————————————— eel
Genus | Paraconids of Mo-3
Chrigcus.— .----=- | Distinct, near meta-
conids, internal.
Vestigial, placed
about as in Chri-
acus or slightly
less internal.
Metachriacus-----
Vestigial, low on
crown, nearly me-
dian.
PMICENLES ===
Mimotricentes_._.| Vestigial, higher on
crown than in
Tricentes and in-
ternal.
About asin Chriacus
or slightly less in-
ternal.
Prothryptacodon..| Comparable to Me-
tachriacus, but
slightly better
differentiated.
Spanoryodon...--
Trigonids of M1-3
in
still
Lower than
Chriacus,
shearing.
Still, lower, buno-
dont.
WiChetmecentesaa = o—
About asin Chria-
cus or slightly
lower.
Cf. Chriacus___..--
Elevated, shearing_
Cuspules of My-3
No accessory cus-
pules.
Tendency to de-
velop cuspules on
anterior rim _ of
trigonid, conules
on both hypoconid
wings, and slight
metastylid.
Enamel rugose or
papillated but few
or no definite cus-
pules.
Chitnicentese= =
Cf. Chriacus. -
Ch Chridcuss2 2 ===
Mi-3
With well-developed
hypocones, some
tendency to devel
op protostyles
Sharp cingulum
around protocones
of M!-3 but hypo-
cones rudimentary
on M?, absent*on
M3, no distinct
protostyles.
Hypocones small or
absent, no proto-
styles.
Cf. Tricentes.
(Unknown.)
(Unknown.)
194 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Renewed study has necessitated some modification of the arrange-
ment given in a preliminary paper (Simpson, 1935d). In the first
place the species there called Ciriacus pusilius was wrongly placed in
Chriacus. It belongs in Metachriacus, where it is indistinguishable
from the genotype, M. punitor. This makes possible some redefini-
tion of Metachriacus, which proves to be even more distinct from
Chriacus than was at first supposed. The species called Tricentes
latidens (quoted from Dr. Gidley’s notes) is now seen to be distinct
from Tricentes, despite a very marked adaptive resemblance, for it has
P;, apparently always absent in Tricentes, and the paraconids are in
quite a different position although reduced about asin Tricentes. It is
necessary to erect a new genus for this species, since redefinition of
Tricentes to include it would make that genus so broad as to destroy
all balance in the generic arrangement of the family achieved by
Matthew and others.
Spanoxryodon is a peculiar type with aberrant specialization, and
Prothryptacodon is evidently a very primitive form slightly but de-
finitely modified in the direction of Thryptacodon.
For convenience in identifying fragmentary material a summary
(table 39) of lower tooth dimensions is here given.
TABLE 39.—Measurements (in mm) of lower dentition in seven species of
Oxyclaeninae!
Py Mi | M; | M3
Species and number of specimens ———————
L WwW L Ww L WwW L WwW
Prothryptacodon furens (2)...-------- 4.9 Qa 5.2 3.7 5.2 4,2 6.3 4.0
TLCRTMACUS DUGNETI() i. 2. see} seseos| so2= 22 |e 55522 (pe! 5.9
Metachriacus punitor (9) ...-----.---- 4.3 27 4.7 Sat 5.0 4.3 Seal 3.7
Metachriacus provocator (12) __..----- 5.0 2.9 54 4.2 5.8 4.9 6.7 4.1
Spanorydon latrunculus (1) ---.------ 5.0 2.8 Baz 3.9 5.8 4.5
Mimoiricentes latidens (2)..-----.---- 5.4 3.9 5.6 4.7 6.0 5.5 6.1 4.7
Mimotricentes angustidens (4)_.------ 4.4 3.0 4.8 3.6 5.6 4.6 5.5 3.6
1 The figures in this table are means for the number of specimens (in all, not necessarily for every dimen-
sion) shown in parentheses. The range of variation is known reasonably well only in Metachriacus punitor
and M. provocator, as given hereinafter. The dimensions in themselves are not necessarily distinctive, for
instance between Metachriacus provocator and Spanoryodon latrunculus, but in such cases there are, of
course, well marked nonnumerical distinctions. Some worn and incomplete specimens might, however,
be unidentifiable in such cases.
Genus PROTHRYPTACODON Simpson
Pr othryptacodon Stmpson, 1935d, p. 233.
Type.—Prothryptacodon furens Simpson.
Distribution —Middle Paleocene, Fort Union, Montana.
Diagnosis.—Canine semiprocumbent, root extending beneath pre-
molars, as in Zhryptacodon. P,-, spaced widely. P, similar to
Thryptacodon. Molar trigonids higher than in Thryptacodon, para-
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 195
conids reduced and in nearly the same position as in Thryptacodon but
more distinct, higher on crown, trigonids less basined, and with fewer
accessory cuspules. Only one distinct inner talonid cusp (entoconid),
as opposed to two in Thryptacodon.
Discussion.—This genus could well be ancestral to Thryptacodon
and in any case is evidently allied to it. The adaptive characters are
somewhat intermediate between the more primitive types, such as
Oxyclaenus, and the more complex type seen in Thryptacodon, involv-
ing some flattening of the molar crowns and proliferation of cuspules.
In these characters Thryptacodon and to a less extent Prothryptacodon
parallel or converge toward the Claenodon—Anacodon line. The latter
group, however, is much earlier and more highly specialized in this
rather bearlike direction. Prothryptacodon is contemporaneous with
Claenodon in the Middle Paleocene, and Claenodon is already more
specialized than Thryptacodon in this direction. Thryptacodon
appears in the Upper Paleocene and survives into the lower Eocene,
where Anacodon appears as a highly aberrant survivor of the Claenodon
group.
The canine is slender, laniary, compressed, with the root con-
siderably larger than the crown and meeting the latter at an angle of
about 135°. The root is implanted almost horizontally and extended
at least to the anterior end of P,. P,, from its alveolus, had a single
root and was well spaced, slightly nearer to the canine than to P,.
P, and P; were 2-rooted, and P, is preceded and followed by a short
diastema. PP, has a very slight internal swelling, high on the crown,
that may indicate an incipient metaconid. In one specimen M, has a
faint external trigonid cingulum, and in another this is more definite.
There are two mental foramina, one beneath P, and one beneath P3
or the anterior end of P,. The other characters of genus and species
are adequately given in the diagnosis and figures.
PROTHRYPTACODON FURENS Simpson
Figure 45
Prothryptacodon furens Simpson, 1935d, p. 234.
Type-—U.S.N.M. no. 9260, right lower jaw with P,-M; and
alveoli. Collected by A. C. Silberling.
Horizon and locality—Gidley Quarry (referred specimen from
Silberling Quarry), Fort Union, Middle Paleocene horizon, Crazy
Mountain Field, Mont.
Diagnosis—Sole known species of genus. Measurements in
table 40.
Remarks—Only two specimens are as yet known, both partia]
lower jaws. U.S.N.M. no. 9262 is from the Silberling Quarry.
196 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
TaBLE 40.—Individual measurements (in mm) of Prothryptacodon furens
Py Mi Ma; M3
Specimen
L WwW L WwW L WwW L WwW
Types Neeley ae ore raze! 4.9 207 5.2 317 5.2 4,2 5.3 4.0
UiSeNeMisn0: 9262424. a. tessa eso ne seco ls See Ue Eee eh aoe 5.1 4.2
Ni
RR Riser
° Cat | hos
FS
cg a
—-
SS Ser
FIGURE 45.—Prothryplacodon furens Simpson, U.S.N.M. no. 9260, right lower jaw: a, Crown view; 6,
internal view. Twice natural size.
FIGURE 46.—Chriacus pugnar Simpson, U.S.N.M., no. 13782, right lower jaw, crown view. Twice natura
size.
Genus CHRIACUS Cope, 1883
This genus typifies the Torrejon but has been reported also in the
Puerco and in the Almagre. It is improbable that a single genus had
this enormous, almost unique length of distribution, and the earliest
and latest forms, known only from fragments, may well prove to be
distinct. The pattern is a simple and generalized one, easily confused
with that of allied forms, and requiring close study and good material
for its certain distinction.
The appearance of Chriacus in the present fauna would be expected,
from its age relationships, and this genus was reported by Douglass
(1908) and by me (1935d). The earlier reports, however now prove to
be doubtful or erroneous. As elsewhere noted, one species hitherto
referred to Chriacus is now placed in Metachriacus. The other,
C. pugnaz, is retained here, but the specimen on which it is based is so
incomplete that the generic reference is not certain.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 197
CHRIACUS PUGNAX Simpson
FIGURE 46
Chriacus pugnax Stmpson, 1935d, p. 235.
Type.—U.S.N.M. no. 13782, right lower jaw with M,_, and alveoli.
Collected by A. C. Silberling and G. G. Simpson.
Horizon and locality—Loc. 78, Fort Union, Crazy Mountain Field,
Mont.
Diagnosis —About the size of C. pelvidens, but molars wider, tri-
gonids less elevated, talonids of M,_, notably wider than trigonids.
M, length 7.1, trigonid width 4.9, talonid width 5.9.
Remarks.—In addition to the characters cited in the diagnosis, there
is a diastema anterior to P;in the unique specimen, but the length and
significance of this cannot be established. The specimen is from one of
the lowest horizons that have yet yielded mammals in this field, only
200 feet above the base of the Fort Union No. 1. This suggests
comparison with Mimotricentes angustidens, also from a low (but not
such a low) horizon, but the latter is markedly smaller and otherwise
less Chriacus-like.
Genus METACHRIACUS Simpson
Metachriacus Simpson, 1935d, p. 235.
Type.— Metachriacus punitor Simpson.
Distribution —Middle Paleocene, Fort Union, Mont.
Diagnosis ——Canine and premolars about as in Chriacus. Molar
trigonids lower than in Chriacus but still shearing rather than bunodont
(as in Tricentes). Paraconids reduced and poorly distinguished, near
metaconids, placed about as in Chriacus or slightly less internal.
Accessory cuspules developing on anterior rim of trigonid, on hypoconid
wings, and a slight metastylid. Upper molars with sharp cingulum
around the protocone, but no protostyle. Hypocone present on M?’,
rudimentary or indistinguishable on M?, and absent on M®.
Remarks.—This genus is hardly distinguishable from Chriacus on
the basis of the premolars, which distinguish it from almost all other
known genera, but the molars are of quite a different adaptive type,
the lower crowns, blunter cusps, and proliferation of accessory cus-
pules in the lower molars representing convergences in varying degree
toward Tricentes and toward Claenodon.
METACHRIACUS PUNITOR Simpson
Figures 47-49
Metachriacus punitor Simpson, 1935d, p. 235,
Chriacus pusillus Simpson, 1935d, p. 234.
Type.—U.S.N.M. no. 9288, left lower jaw with M,-3. Collected by
A. C. Silberling.
198 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Paratype.-—U.S.N.M. no. 9286, right lower jaw with P;—-M; (M, and
M; broken). Collected by A. C. Silberling.
Type of Chriacus pusillus—U.S.N.M. no. 9270, right lower jaw with
P.-M;. Collected by Dr. J. W. Gidley.
Horizon and locality —Gidley and Silberling Quarries, Fort Union,
Middle Paleocene horizon, Crazy Mountain Field, Mont.
:
te
‘ED
"
EE
FIGURE 47.—Metachriacus punitor Simpson: a, U.S.N.M. no. 9288, left Mi-3 crown view; 6, U.S.N.M. no.
9286, with parts in outline from nos. 9282 and 9486, right lower jaw, external view. ‘Twice natural size.
H \ 4ff Z
\\ \ At y I,
SR Sey (2 (ee
FIGURE 48.—Metachriacus punitor Simpson, small variation, U.S.N.M. no. 9270, right lower jaw, internal
view. Twice natural size.
FIGURE 49.—Metachriacus punitor Simpson, U.S.N.M. no. 9331, left M!-3, crown view. Four times natural
size.
Diagnosis.—Heel of P, expanded, basined, squarely truncated pos-
teriorly. Molar crenulation moderate. My,_». less wedge-shaped.
Measurements given in tables 42 and 43.
Discussion.—My earlier publication on the two species here united
was confused and incorrect. By a misinterpretation of a small worn
specimen and by the acceptance of an incorrect association, I was led
to place a few of these specimens in Chriacus and therefore I did not
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 199
properly compare them with the better materials manifestly belonging
in a distinct genus, named Metachriacus. With the removal of the
extraneous material and renewed comparison of a large number of
specimens, it is clear that Metachriacus punitor and ‘‘Chriacus pusillus”
both belong in Metachriacus. The specimens previously referred to
“Chriacus pusillus”’ are smaller than those placed in Metachriacus
pumitor, and M; is slightly more reduced. Nevertheless, with recog-
nition that they are congeneric and in view of the fact that all are
from one horizon and locality it appears that no sharp division
between the small and large specimens can be made and that they
are merely individual variants of one species. This is borne out by
the statistical constants given below.
Of I,-P, only the alveoli are known. Judged from these, there
were three small, subequal, closely crowded incisors, the canine was
moderately enlarged and procumbent (but less so than in Prothrypta-
codon), and P, was a small tooth implanted vertically by a single
root. P23 are similar, but P; is larger. Both are slender, 2-rooted,
pointed teeth, the outer face convex, with a sharp anterior crest and
the posterior and anterointernal faces excavated. There is a small
barely cuspidate heel and a tiny anterior basal cuspule. PP, is con-
siderably longer than P; although barely higher. The anterior cuspule
is more distinct and the talonid much more developed, its internal
half basined. There is a high rudimentary metaconid, not well differ-
entiated from the protoconid, closely similar to that of Chriacus.
The lower molars are of generalized arctocyonid type except for the
special characters already listed.
The symphysis is shallow, weak, and unfused, the horizontal ramus
long and slender, the mental foramina beneath P, and P3.
Upper teeth have not been found associated with lower jaws of
Metachriacus punitor, but there are several isolated upper teeth and
jaw fragments, including representatives of the three upper molars,
that are from the same level and locality, are harmonious in size and
structure, and may be referred to this species with some assurance.
In outline they closely resemble Chriacus but are distinguished by the
entire absence of a protostyle and the considerably lesser development
of the hypocone.
TABLE 41.—IJndividual measurements (in mm) of Metachriacus punitor
P: P3 | Py Mi M: M;
U.S.N.M. no. | | Ss | S| MH —_ | ——_——_
L WwW L WwW L WwW L Ww L WwW L Ww
PAS Se re Papa tee ee | eee | | eee el oe eee eS] MES) | ech el c hes PAGE) 3.8
OUS6 eee ace aaa e eens | eee ae ea| ee eee ee eee Ca. 14714 || 2:9! (2s 222 3.9] 52) 4.4
O27 OLN ssa Eases ee 2.8} 1.6] 3.5] 2.0 4.4) 2.6) 49] 3.7] 50] 43
119212—37——14
200 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Measurements of the three principal specimens and statistical con-
stants of the whole series are given in tables 41 and 42 (see also fig. 4).
TABLE 42.—Numerical data on lower dentition of Metachriacus punitor
Variate N R M o V
Joye son as 6 4, 1-4. 7 4, 32+90. 08 0. 20+0. 06 4,541.3
WAR eee eae 6 2. 4-3. 0 2. 72+0. 08 0. 20+0. 06 (silts Daves
iMG ste eae 5 4,4-4.9 4. 6640. 07 0. 16+0. 05 3. 5#1.1
WieM ewe ote Se 8 3. 5-3. 9 3. 71+0. 05 0. 16+0. 04 4.1+1.0
Mig eee 8 4, 6-5. 4 4. 98+0. 09 0. 27+0. 07 5. 441.3
Wiens Seiad 9 4, 1-4, 5 4, 31+0. 04 9, 11+0. 03 2.6+0.6
AIM ee eee 6 5. 1-6. 1 5. 72+0. 14 0. 354.0. 10 6.2+1.8
IWiMig ees 6 3. 6-3. 8 3. 688+0. 04 0. 09 +0. 03 2.4+0.7
Three specimens from the Silberling Quarry, all very incomplete,
are referred to this species. Each is somewhat aberrant but not
consistently among the three and not beyond the established range of
variation. They are not included in the figures in table 42, which are
based on a pure sample from the Gidley Quarry.
METACHRIACUS PROVOCATOR Simpson
Figures 50-52
Metachriacus provocator Stmpson, 1935d, p. 235.
Type.—U.S.N.M. no. 9278, left lower jaw with P,-M3;. Collected
by Dr. J. W. Gidley.
Horizon and locality—Type from Loc. 51, referred specimens from
Locs. 81, 50, 25, 24 (all below Gidley Quarry), Fort Union, Middle
Paleocene horizon, Crazy Mountain Field, Mont.
Diagnosis.—Heel of P, less expanded, little or not basined, more
pointed posteriorly. Molars markedly crenulated. M,-, more
wedge-shaped, i. e., talonids markedly wider than trigonids. Slghtly
but significantly larger than M. punitor in most dimensions (see
table 43).
Discussion.—This species was originally based on three specimens
(Simpson, 1935d), but since then five more, less complete, have been
identified in the National Museum collection, and 10 have been col-
lected for the American Museum, so that it is now one of the best-
known species in the fauna. It does not occur in the quarries, where
it is replaced by the allied but certainly distinct M. punitor, but occurs
at the widely scattered Locs. 24, 25, 50, 51, and 81 (specimens from
25 and 81 only in the American Museum, but used in this study), all
of which are somewhat below the quarries, although all in Fort Union
No. 2. Both upper and lower jaws are known from each locality. It
is probable that the distribution, below the quarry levels, is accidental,
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 201
that is, that VM. provocator is not a significantly older species replaced in
time by M. punitor, but that they may well have been really contem-
poraneous but living in different facies.
In addition to the characters cited in the diagnosis, the two speci
mens of M. provocator that show the alveoli of P, had this tooth
relatively more reduced than in M. punitor, with more definite diaste-
mata before and behind it.
The upper molars, well known in this species, have the hypocones
more definite and more projecting internally than in M. punitor, and
M3 is less reduced and less transverse. There is also a tendency to
develop a rudimentary protostyle on M?. These characters make the
upper teeth closer to Chriacus than are those of M. punitor, and the
upper dentition of M/. provocator would not perhaps in itself be sepa-
rated generically from Chriacus, but its lower dentition shows the
generic characters even more clearly than does that of M. punitor.
There are three lower and three upper jaws, some associated, from
each of Locs. 25 and 51, three lower and one upper from Loc. 81, two
lower and one upper from Loc. 50, and one lower and one upper from
Loc. 24. Deviations exist, of course, between the material from dif-
ferent localities, but these are not consistent and are not statistically
significant. The samples are too small to demonstrate racial dif-
ferences, if such exist. In fact the whole combined sample does not
exceed the variety usual in a homogeneous species but on the con-
trary shows unusually small variation, as shown by the figures in
table 43 (see also fig. 4).
TaBLE 43.—Numerical data on upper and lower dentition of Metachriacus
provocator
Variate N R M z(d?) o V
Mies 22S 3 | 4.8-5.1 | 4. 97 0. 0467
WP ee Soc s}) 63) (289 2. 90 0
2h Ee 7.| S.2—5 S |Pbrot 2 0008nieS 2522 0. 205+0. 055 | 3.84+1.0
Winineson sos 7 |) 359-45 63 a4. 20.09) |b=s5-5=" 0.24 +0. 06 o. 7£1.5
ih oe (ta G-OR0 2 057 93-05 Os |e oee = 0.12 +0. 03 2. 2+0. 6
i. ho 1. \245G-55 214s Ole OS OF (eee seoee 0.19 +0. 05 3.8+1.0
oie | 4 6 TOF |" 6.70 0. 1400
Wise. 5 | 4.0-4.3 | 4. 12 0. 0680
LE yee 2 | 4.6-5.0 | 4 80 0. 0800
iG Sa ae 2) 4.8 4, 80 0
1G) Ee 5 | 5..0-5. 4 |. 5. 18 0. 1080
END re 2 ra 5 | 6. 1-6. 7 | 6. 30 0. 2600
iia ae 7 oe ao. iMon.)O7 2-0, OO: | 225 ee 2 0.24 +0. 06 4.2+1) i
NV NES ee oe etl) ee Seed lero Os OF wee oe ee | 0.18 +0. 05 2.4+0.6
1S). OS ee 4|4.3-4.8 | 4 55 0. 1700
sid Sale eee 4 | 5.8-6.4 | 6.15 0. 2700
In only one case does the coefficient of variation exceed 5 (this
would be true also if this coefficient were calculated for all the variates).
902 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
ign
FIGuRE 50.—Metachriacus provocator Simpson, U.S.N.M. no. 9278, left lower jaw: a, Crown view; 6, internal
view. ‘Twice natural size.
Figure 51.—Metachriacus provocator Simpson: a, U.S.N.M. no. 15126, left M2-3, crown view; 6, U.S.N.M.
no. 9259, right lower dentition, crown view. ‘Twice natural size.
FIGURE 52.—Méetachriacus provocator Simpson, U.S.N.M. no. 9259, left M!-*, crown view. Four times
natural size.
The difference from M. punitor is so obvious that its significance
requires no proof. In every case the deviation between the means is
significant, and in the available samples the observed ranges overlap,
barely, only for the widths of Py and M,.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 203
The individual dimensions of the type lower jaw are as follows:
Length Py, 5.0; width P,, 2.9; length M,, 5.5; width Mj, 4.1; length
M2, 5.7; width M,, 5.2; length M3, 6.5; width Ms, 4.0.
Genus SPANOXYODON Simpson
Spanoxyodon Simpson, 1935d, p. 236.
Type.—Spanoxryodon latrunculus Simpson.
Mstribution.—Middle Paleocene, Fort Union, Montana.
Diagnosis.—P_2 absent and long diastema between canine and P3.
P3_, much as in Chriacus, but Ps with metaconid larger, higher, and
more distinct. M,-, about as in Chriacus or with trigonids slightly
lower and paraconids slightly less internal.
Remarks.—Only one specimen referable to this genus is yet known,
and its characters are adequately summed up in the diagnosis.
SPANOXYODON LATRUNCULUS Simpson
Ficure 53
Spanoxyodon latrunculus Stimpson, 1935d, p. 236.
Type.—U.S.N.M. no. 9287, left lower jaw with canine alveolus and
P;-M;. Collected by Dr. J. W. Gidley.
Horizon and locality.— Gidley Quarry, Fort Union, Middle Paleocene
horizon, Crazy Mountain Field, Mont.
Diagnosis.—Sole known species of genus. Measurements of type
as follows: Length P3, 3.8; width P3, 2.3; length Py, 5.0; width P,, 2.8;
length M,, 5.2; width M,, 3.9; length Mz, 5.8; width Mg, 4.5.
MIMOTRICENTES,*® new genus
Type.—Tricentes latidens Gidley.
Distribution.—Middle Paleocene, Fort Union, Montana.
Diagnosis.—Adaptively and structurally closely similar to Tri-
centes, but P, present, no marked diastema, and molar paraconids
higher on crown and internal, not median, in position.
Discussion.—In my preliminary paper I left the type of this genus
in Tricentes, where Dr. Gidley had placed it. On further study, how-
ever, I am forced to erect a new genus for it. The resemblance to
Tricentes is close, but in the latter P, is apparently invariably absent
(the name Tricentes refers to the presence of only three premolars,
striking in this primitive fauna), and the paraconids of M2-; are quite
different. The former might be only a primitive character and not
surely of generic rank if unaccompanied by other differences. The
character of the paraconid, however, as reduced as in Tricentes but
in a different way, removes this form from the Tricentes lineage and
may even mean that the relationship is not closer to that genus than
89 Miyos, an imitator-+ Tricentes.
204 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
to other primitive arctocyonids and that the resemblance is purely
convergent, aside from the fact that both have the stereotyped pattern
of all these ancient forms.
The canine, preserved in the type, has a large root and is curved in
a pronounced arc. The crown is unusually erect, as it is also in Tri-
centes. P, is known only by its alveolus, which is single and rather
large. The premolars very closely resemble those of Tricentes, except
FIGURE 53.—Spanozyodon latrunculus Simpson, U.S.N.M. no. 9287, left lower jaw: a, Crown view; 8, inter-
nal view. Twice natural size.
Smads ( ada.
uy pe uy We
FIGURE 54.—Mimotricentes latidens (Gidley), U.S.N.M. no. 9269, left lower jaw: a, Crown view; 0, internal
view. Twice natural size.
that the heel of P, is more expanded transversely and its posterior
border is more nearly a straight transverse line—a distinction prob-
ably not generic, as it is closely similar to that between Metachriacus
punitor and M. provocator. The molars are even flatter and broader
than in Tricentes but otherwise closely resemble those of that genus
except for the difference in the paraconids. Upper teeth are known
only in one specimen, mentioned below.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 205
MIMOTRICENTES LATIDENS (Gidley)
Figure 54
Tricentes latidens GipLEY, Simpson, 1935d, p. 236.
Type.—U.S.N.M. no. 9269, left lower jaw with canine and P,-M3.
Collected by Dr. J. W. Gidley.
Horizon and locality Gidley Quarry, Fort Union, Middle Paleocene
horizon, Crazy Mountain Field, Mont.
Diagnosis —Length: width ratio (type only): M, 1.09, M; 1.30.
Measurements given in table 44. Paraconids vestigial and trigonids
short.
Discussion.—This species is known principally from two good
specimens from the Gidley Quarry, the type and U.S.N.M. no. 9276,
a right lower jaw with P,-M, (M, broken), confirming but not adding
to knowledge derived from the type. There are two other specimens
from the Gidley Quarry, probably of this species but of no value, and
two, also very fragmentary, from the Silberling Quarry. One of the
latter, U.S.N.M. no. 9672, with P, and M,, is smaller and less robust
than the type, with the paraconid of M, more distinct, but it might be
a variant of this species.
The only known upper teeth of this genus, and probably but not
surely this species, are M? from Loc. 81, in the American Museum
collection. Like the lower molars, they closely resemble those of
Tricentes, the only clear difference, and this of doubtful value, being
that the internal cingulum does not circle the protocone and that on
M? the external cingulum does not cross the paracone.
TABLE 44.— Measurements (in mm) of the two principal Gidley Quarry specimens of
Mimotricentes latidens
P2 P3 Py Mi M2 M3
U.S. N. M. no. a a le eS E |
L W L W L W L WwW L W L Ww
260E ese saan sess seek 3.6 2.8 4.6 3.3 5.4 4.0 655) 4.7 6.0 5.5 6.1 4.7
EIA Ohio a se ee BEET fees iiac eael| ESR | ate eo RRSIMl bas 7/6| ae oa
MIMOTRICENTES ANGUSTIDENS," new species
Figure 55
Type-—U.S.N.M. no. 9277, left lower jaw with P,-M:. Collected
by A. C. Silberling.
Horizon and locality —Type from Silberling Quarry. Referred speci-
mens, not identified with complete certainty, from Locs. 51 and 73.
Fort Union, Middle Paleocene horizon, Crazy Mountain Field,
Mont.
% Angustus, narrow+dens, tooth.
206
BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Diagnosis.—Very slightly smaller than M. latidens. P, relatively
smaller, slender, and with paraconid much stronger. Molars rela-
tively narrower. Length: width ratio of M, (of type) 1.24. Para-
conids less reduced and trigonids less compressed than in M. latidens,
trigonids about equal to talonids in size.
Discussion.—The difference in size is slight and may not be sig-
nificant, but the differences in structure and proportions are marked
and sharply distinguish this from M. latidens. The type has another
distinction, not cited in the diagnosis, in the fact that the talonid of
M, is definitely narrower than the trigonid, while in M. latidens it is
of equal width or slightly wider than the
trigonid. There are, however, two isolated
M.,’s from Loc. 50 that closely resemble M.
angustidens but that have the talonid in
one equal to the trigonid and in the other
slightly wider. At present it seems more
probable that this is a variable character
in the species than that these teeth rep-
resent a third species.
Princeton no. 13758 is a left lower jaw
with M,_3, from Loc. 73, especially inter-
esting because it is from the Fort Union
S)
Ne,
LKS ay
Wee
iy ANS Wy, &
a { \ na Ks Ze St
Aton pw
nr a
FIGURE 55.—Mimotricentes angusti-
dens, new genus and species, Prince-
ton Univ. no. 13758, left lower jaw, a,
Crown view; b, internal view. Twice
No. 1, where fossils are very rare and be-
cause it is, as far as I know, the only fossil
mammal ever found in sandstone in this
natural size.
field. Its M, agrees very closely with the
type of M. angustidens except that the talonid is as wide as the trigo-
nid. M,; differs from that of M. latidens in the same way as does M3,
being relatively narrower, with stronger paraconid and _ longer
trigonid.
The dimensions of the four specimens mentioned are given in
table 45.
TaBLE 45.—Individual measurements (in mm) of lower dentition of Mimotricentes
augustidens
Pa Mi M; Ms
Specimen
L Ww L WwW L Ww L w
UESSNeMin on O27 72s. ase oo ee 4.4 3.0 4.8 3.6 5.6 4.5
WES Ne Meno $9706 See eee Se a SA os Sit ee | 5.6 4.6
UcS ANGIE OS O05 sss 2 Bee 8 IE Eee ee SUE AE | ee ae 5.6 4.5
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 207
?MIMOTRICENTES species
U.S.N.M. no. 6178 is a left M, from Loc. 9, at a low level in the
formation. It apparently belongs in this or a closely allied genus.
Its dimensions, 6.2 by 5.2 mm, are perhaps not significantly different
from those of M. latidens, although it is relatively somewhat narrower.
The trigonid is distinctly longer than in the type of the genus and
about equal to the talonid in size, not distinctly smaller as in the type.
Although inadequate for identification, the occurrence merits mention
in view of the horizon represented.
Family MIACIDAE Cope, 1880
The known history of the Miacidae is anomalous and emphasizes
the inadequacy of some of our knowledge of details in this early epoch
and the probably erroneous character of some negative conclusions
regarding it. The miacids (so carefully and fully defined by Matthew
in many works that diagnosis here is unnecessary) are a specialized
group, for in them the carnassial shearing teeth are very well devel-
oped, despite their absence in all other known Lower and Middle
Paleocene mammals. Furthermore, they are an adaptive and potent
group, for their carnassials are M, and P*, as in the Carnivora (vera)
or Fissipedia and there is every reason to believe that they are, in a
broad sense, ancestral to all the latter. The appearance of this ap-
parently modernized group in a fauna otherwise almost wholly archaic
is extraordinary.
The known distribution within the family is also noteworthy. The
first genera to appear, and the only ones known before the true Hocene,
are not the most primitive and generalized and are not ancestral,
even structurally, to the majority of later types. All have lost M%,
unquestionably present in the ancestry. Even aside from the fact
that these teeth are present in most later miacids, they are almost
universally present in Middle Paleocene mammals of other families.
This anomalous history must involve, first, rapid progressive evolu-
tion of the group generally, the Miacidae, which is not surprising in
view of later history, which shows this general type to be probably
the most plastic and adaptive of allmammals. Second,itmustinvolve
the early, minor differentiation of a special line, the Viverravinae,
which entered the regions known to us paleontologically at about the
beginning of the Middle Paleocene, while the more varied adaptive
Miacinae were confined, until the great Eocene invasion, to some
facies or region still unknown to us.
In speaking of the Miacidae as specialized, it is important to em-
phasize the relative value of the words. They are specialized in com-
parison with the extraordinarily archaic contemporaneous Arctocyo-
nidae, which are not far from being generalized primitive placentals,
but in comparison with the other carnivores, specifically with the
208 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
fissipedes, they are extremely primitive, much more so than any
Tertiary dogs or other true fissipedes. The anomaly is thus not so
striking as might appear at first sight. Furthermore, within the family
the Paleocene forms are distinctly more primitive than Eocene Viver-
ravinae and are certainly not ancestral to the Miacinae, so that com-
parison with the latter is misleading. On a small scale, within the
family, the Viverravinae are a miniature “archaic” radiation of
Miacidae and the Miacinae a later “progressive” radiation, much as,
on a far grander scale, the peculiarly specialized periptychids are an
archaic radiation and the basically more primitive hyracotheres are
a progressive radiation among the ungulate cohort.
There are two distinctive genera of miacids in this fauna, Didymictis,
evidently an abundant form with several species and long known
from the distant Torrejon (as well as from numerous later horizons),
and Ictidopappus, a rarer type known from only two specimens in this
fauna and as yet unknown elsewhere.
Subfamily VIVERRAVINAE Matthew, 1909 (Viverravidae Wortman
and Matthew, 1899)
Viverravus, Didymictis, and Ictidopappus evidently form a closely
related group characterized, among other features, by the prominent
anteroexternal cuspule of P*, the elongate oval outline of M?, and the
absence of M’; (Matthew, 1915). For this group the name Viverra-
vinae is available, contrasting with the typical miacids, the Miacinae.
As mentioned below, Didymictis may be a compound genus, but if so
its components are very closely related. Viverravus, also, is a some-
what doubtfully bounded genus. Its earlier, lower Eocene species
are very close to Didymictis, while some of its later, middle Hocene
species, perhaps including the genotype, are so markedly advanced
over the early forms that they might not ordinarily be placed in the
same genus. This point is not here apropos, but Viverravus is of some
present interest because of the possibility of special relationship to
Ictidopappus.
Viverravus and Didymictis were separated by Matthew (1915) on
the basis of the crested heels of M,_, in the former, basined in the
latter. In fact the early species of Viverravus (e. g., V. acutus, V.
politus, and even the slightly later V. dawkinsianus) do have basined
talonids, although they are obviously becoming crested by emphasis
of the hypoconid and marked reduction of the entoconid. In Jcti-
dopappus the talonids are quite as basined as in Didymictis, a condition
doubtless ancestral for Viverravus also but partly or completely lost
in species definitely referable to that genus. Aside from the difference
in the heel, relatively slight at the beginning of the Eocene, the early
species of Viverravus also differ from Didymictis in the longer, lower
trigonid of M,, which is a striking resemblance to Ictidopappus.
209
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT.
Were it not for the unusual proportions and simple structure of Py,
Ictidopappus would make an ideal ancestor for Viverravus. Some
species of the latter, e. g.,V. acutus, have P, small and simple, but much
more trenchant than in Ictidopappus, strongly compressed laterally,
the posterior cusps well developed, and all cusps in a straight line, not
subtriangular. The Ictidopappus P, might be ancestral to this, but
there is no good evidence that it was, and Viverravus may after all be
an offshoot of Didymictis in which the trenchant P, was already highly
developed in the Middle Paleocene.
Genus DIDYMICTIS Cope, 1875
This exceptionally long-lived genus is recorded from all levels from
the Torrejon to the end of the lower Eocene. During this period
there is not only definite evolutionary advance but also evidence of
the presence of several different phyla. It is quite possible that one
or more of these can be and should be separated generically, but the
criteria for doing so are poor at present. A useful step was Matthew’s
(especially 1915) revalidation of Viverravus, which was long confused
with Didymictis or considered a synonym. Now Matthew (Pale.
Mem.) has further separated the sole Torrejon species, D. hay-
denianus, and placed it in a new subgenus, Didymictis (Protictis), with
the suggestion that this may prove to be of generic rank.
The most abundant species in the present collection, D. microlestes,
introduces some difficulty in this arrangement. In its more important
morphological characters it compares with the types of Didymictis
(Protictis) and of Didymictis (Didymictis) as shown in table 46.
TaBLE 46.—Comparison of dentition characters of three species of Didymictis
Species P3 Protocone of M! Proportions of M!-4
D. (Protictis) hay- | With rudimentary proto- | High, angulate, posterior | Strongly transverse, M?
denianus. cone. wing weak. reduced.
D. microlestes_-__-- Intermoediates=--22 5223-25 AsineD iprotenussss-cs----—- Asin D. protenus.
D. (Didymictis) | Compressed, no proto- | Broader, wings equal-_--_---- Less transverse, M? less re-
protenus. cone. duced.
SSS ————EoEEESESESESESESEaEaESESaSaSpapaSSSEESESESESESESESESESESESESESESESESESSSS=S=S=SS=—="
Species P3 P41 Ma
D. (Protictis) hay-
denianus.
With very minute anter-
ior cuspule, heel crested
without distinct cusp.
With relatively large an-
terior cusp, heel with
small basin and crest
with rudimentary cusp.
Witb minute anterior and
large posterior accessory
cusp, no basin.
D. microlestes_----
D. (Didymictis)
protenus.
With distinct, nonshearing
anterior cusp, 2 talonid
cuspules, small basin.
With anterior cuspule large
and shearing, 1 talonid
cuspule, small basin.
With trigonid somewhat
elevated and shearing,
heel reduced.
Trigonid comparable to D.
haydenianus, heel less re-
duced.
With anterior cuspule very | With trigonid low, tuber-
small, nonshearing, 1 tas
lonid cuspule, basin very
poorly developed or ab-
sent.
cular, heel not reduced.
210 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
The upper teeth, although much smaller and lighter in construction,
resemble D. protenus rather than D. haydenianus. These are probably
primitive characters, and D. haydenianus is slightly aberrant. The
development of P3_, is also somewhat closer to D. protenus, and it is
not clear that this is wholly in primitive characters. The presence
of only one talonid cusp on P, may be, but it is unlikely that the more
cuspidate P3 is primitive. The development of relatively large and
shearing anterior cuspules on these teeth is different from either
D. haydenianus or D. protenus and seems to be a specialization.
M; is perhaps merely primitive with respect to either of the other
two species.
It is possible that D. microlestes stands nearer the D. protenus
ancestry than does D. haydenianus, in which case the subgeneric
separation might well be maintained, and D. microlestes would belong
to the typical subgenus. The evidence for this is not very good,
however, and for the present it seems best not to attempt a subdivision
of the genus.
There is another Didymictis-like species in the fauna, D. tenuis, of
very diminutive size. At present it is known from a single specimen,
and, as noted below, there is some doubt as to the charcters of Py.
If they were confirmed the species could hardly be placed in Didy-
mictis, but knowledge is now so imperfect that it seems best to leave
it here until further evidence is at hand. Table 47 gives an idea of
the very considerable differences in the length of M,; among the three
Middle Paleocene species referred to Didymictis:
TaBuie 47.—Length of Mé, in three species of Didymictis
Species N R M
D;-haydentanus—Torrejon25. 22-28. 2225. 222 6 7. 5-8. 0 7. 72
LD NECT OLCSLCR ores Ss Oe StS ee he 8 4, 3-5. 1 4, 66
Dissteniient aes oS 2 oe oe et SN oe AGREE Ae oe 2.9
There are also a few specimens too imperfect for exact identification
that are comparable in size to D. haydenianus and cannot at present
be distinguished from that species.
DIDYMICTIS MICROLESTES Simpson
Figures 56, 57
Didymictis microlestes Stmpson, 1935d, p. 238.
Type.—U.S.N.M. no. 9301, left lower jaw with P,-M>. Collected
by Dr. J. W. Gidley.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 211
Horizon and locality —Gidley Quarry (one referred specimen from
Silberling Quarry), Fort Union, Middle Paleocene horizon, Crazy
Mountain Field, Mont.
Diagnosis —Much smaller than D. haydenianus or any known later
species (see measurements below). P3 similar to P,, but cuspules
less well developed. Py, with large anterior cuspule, developed into
a small shearing blade, talonid relatively broad and less rounded than
in‘other species, with one main cusp. M, with slightly elevated and
shearing trigonid, talonid reduced.
< i
rl Peele =
A
ry ee
FIGURE 56.—Didymictis microlestes Simpson, U.S.N.M. no. 9301, with parts in outline supplied from
U.S.N.M. nos. 6146 and 9306, left lower jaw: a, Crown view; 6, internal view. Three times natural size.
FIGURE 57.—Didymictis microlestes Simpson, U.S.N.M. no. 9299, with part in outline supplied from no.
6147, left P’-M?4, crown view. As preserved, P? is reversed (or rotated 180°) from the position shown
in the drawing, but this is believed to be accidental. Three times natural size.
Discussion.—The morphological characters of this elegant little
species have been fully brought out in the comparison and diagnosis
above. The principal available numerical data on the lower dentition
are given in table 48.
TaBLE 48.—Numerical data on lower dentition of Didymictis microlestes
Variate N R M o V
Tig seest ON aE 7 4.1-5.0 | 4.49+0. 11 0. 28 +0. 07 6.2+1.7
Wires) sk i 2.0-2.5 | 2.17+0. 06 0.17 +0. 04 7. 742.0
IL ee ee Te 8 4, 3-5.1 | 4. 66+0. 09 0.26 +0. 06 5.641. 4
WIMg eee 2 8 2. 9-3. 2 | 3. 0O8+0. 03 0. 097+0. 024 3.1+0.8
1G Foe ee 4 3. 4-3. 8 | 3. 65 [= (d2) =0. 0900]
Wie 2 4 PFI By | PA PAD [=(d?) =0. 0100]
212 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
The type happens to be an unusually small specimen. It measures:
Length P,, 4.2; width P,, 2.1; length My, 4.3; width M;,, 3.2; length Ma,
3.4; width Mp, Didi
Only two upper jaws and an isolated carnassial are at hand, measure-
ments of which are given in table 49.
TaBLeE 49.—Individual measurements (in mm) of upper dentition of Didymictis
microlestes
ps M! M2
U.S.N.M. no.
L W L Ww L Ww
ODO O mc, ee Nae a een oe 3. 9 4.2 5. 4 2. 4 4.0
G3 Rae uteri attic yas 4.9 ‘atte! 4.3 Sell 2.5 3. 9
GA ip eek eke 2 Laie ol oual 4,1
FIGuRE 58.— Didymictis tenwis Simpson, U.S.N.M. no. 9297, left lower jaw: a, Crown view; 6, internal view..
P, is broken, and it may not be correctly placed. Six times natural size.
DIDYMICTIS TENUIS Simpson
Fiaure 58
Didymictis tenuis Simpson, 1935d, p. 238.
Type.—U.S.N.M. no. 9297, part of left lower jaw with M, and
broken ?P;. Collected by Dr. J. W. Gidley.
Horizon and locality.— Gidley Quarry, Fort Union, Middle Paleocene
horizon, Crazy Mountain Field, Mont.
Diagnosis —Much smaller than any known comparable miacid.
M, with very elevated trigonid, hypoconid and entoconid about
equally high and distinct. M, length 2.9, width 1.8.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 213
Remarks.—As the specimen is preserved there is a small tooth
anterior to M, that has been cemented to the specimen without any
clear or certain contact. Knowing the care with which Dr. Gidley
worked, I have no doubt that this tooth was found with the specimen,
but not knowing his exact evidence of association I am not certain
that it is in fact P, of this individual. It is, furthermore, somewhat
incomplete. It appears to be a very small and simple tooth with a
short, high, conical main cusp and a single conical posterior cusp. If
these are its true characters, it is very much unlike P, in any species
certainly referred to Didymictis, but this is too uncertain to draw any
conclusion, and the lower carnassial is sufficiently Didymictis-like to
leave the species in that genus at least until better material is found.
DIDYMICTIS HAYDENIANUS Cope, 1882
Fiaure 59
U.S.N.M. nos. 6143 and 6145, each including an upper P*, represent
a species inseparable from Didymictis haydenianus. Their most
reliable dimension, the (oblique)
length of the straight shearing edge,
is 10.7 and 9.7 mm, respectively.
In Torrejon specimens referable to
D. haydenianus this dimension is
9.2-11.3 mm. No constant morpho-
logical difference is seen. The ma-
terial is inadequate to establish
definitely that the Fort Union form
is exactly the same as that from the a bd,»
a me eT Pes POPE op Lae acl ear
separable. no. oe left upper jaw with carnassial, crown
Be map ican Museum eollee- (hak on tee ence ae
tion there is a specimen from Loe. same, anteroexternal view; 6’, same, postero
81 ae broken PY anduNitiwihe internal ie a ae ae ere cross-
oblique length of the shearing crest
cannot be measured exactly, but it was about 11.2 mm near the
known upper limit for D. haydenianus. The specimen is more robust
than the two mentioned above and might be a large variant of the
same form or a different subspecies or species.
There is also a fragment of a Py, including the heel, U.S.N.M. no.
9930, from Loc. 51, that has the size and cusp structure of D. hay-
denianus, quite unlike D. microlestes.
Genus ICTIDOPAPPUS Simpson
Ictidopappus Stimpson, 1935d, p. 2387.
Type.—Ictidopappus mustelinus Simpson.
Distribution.—Middle Paleocene, Fort Union, Montana.
214 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Diagnosis.—Differing from Didymictis in the relatively smaller and
much simpler P3;-, and relatively lower and longer trigonid of M,,
from Viverravus in the wider and more triangular P,; and more defi-
nitely basined talonids, and from other known miacids in the absence
of M3.
FIGURE 60.—Ictidopappus mustelinus Simpson, U.S.N.M. no. 9296, right lower jaw: a, Crown view; 3, in-
ternal view. ‘Three times natural size.
Figure 61.—Ictidopappus mustelinus Simpson, U.S.N.M. no. 9295, left upper jaw, in two fragments but
associated, crown view. ‘Three times natural size,
ICTIDOPAPPUS MUSTELINUS Simpson
Fiaures 60, 61
Ictidopappus mustelinus Stmpson, 1935d, p. 237.
Type.-—U.S.N.M. no. 9296, right lower jaw with P;—-M, and talonid
M2. Collected by A. C. Silberling.
Horizon and locality—Gidley Quarry, Fort Union, Middle Paleo-
cene horizon, Crazy Mountain Field, Mont.
Diagnosis.—Sole known species of genus. Measurements below.
Discussion.—From the alveoli the canine was a large procumbent
tooth and was followed by a diastema. P, may have been absent and
P, 1-rooted, but this is not certain. P;is a very small and simple tooth
consisting of a somewhat compressed main cusp followed by a slight
unbasined heel. P, is shorter than M, but nearly as high and is sub-
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 215
triangular. There is a small anterointernal cusp, resembling a rudi-
mentary paraconid rather than the anterior basal cuspule of Didymictis,
and there is a very slight and uncertain indication of a rudimentary
basal metaconid. The talonid is very short and wide and vaguely
cusped. There are no other cuspules or cingula.
M, has a large but, in comparison with Didymictis, low trigonid
elongate anteroposteriorly. The talonid is very small, with distinct
but not prominent hypoconid, hypoconulid, and entoconid developed
on its raised rim. Its well-developed basin opens internally, between
entoconid and metaconid base. My, was evidently much reduced.
The talonid is small but is elongate and basined, with the three cusps
poorly differentiated. The specimen is broken immediately posterior
to this, but from the shape of the talonid of M, it cannot have been
followed by another tooth. Dimensions are as follows: Length P3, 2.0;
width P;, 1.4; length P,, 2.9; width P,, 1.9; length M,, 3.8; width
Wi 200
There is a specimen, U.S.N.M. no. 9295, a left maxilla with P!, P°-
M?, and the alveolus of the canine, that is probably the upper jaw of
Ictidopappus mustelinus. Its size is exactly right for occlusion with
the type, it has P? much smaller than in Didymictis, harmonious with
the smaller P, of the type, and it has M'-? markedly shorter than in
Didymictis, harmonious with the shorter M, and heel of M, of the type.
The only feature suggesting distinction is the embrasure between
P* and M!, the outer angle of which is much more acute than the outer
angle of the trigonid of M,, which fits into it. This, however, does not
prevent normal occlusion, as it might at first sight appear todo. In
Didymictis, also, the embrasure angle is more acute than the occluding
trigonid angle. Occlusion is not strictly orthal but is oblique, in part
ectal (in fact nearly analogous to the triconodont occlusion but, unlike
triconodonts, interlocking). At the close of the bite the external
trigonid angle is internal to the embrasure angle, and the trigonid fits
into the wider internal part of the embrasure and does not coincide
with it. It cannot be proved that this upper jaw is of Ictidopappus,
but it is highly probable, and it should not be assumed to be distinct.
The generic distinction of the upper jaw is very marked. The
canine was relatively large, its alveolar wall swollen, much as in the
most advanced and quite unlike the primitive species of Didymictis.
P! is present and a small simple tooth probably with two roots but
with alveolar mouths confluent. (P? is represented by one root, the
specimen being broken here.) P* is much smaller than in Didymictis.
Its ectoloph is similar in form. The pronounced inner spur, worn
but probably not cuspidate, is median and has a separate and strongly
divergent root. The ectoloph of P* is also similar to Didymictis but
has a more decided notch in the external contour and is without a
cingulum. The protocone spur is slenderer, perhaps less definitely
1192123715
216 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
cusped (worn) and projects almost directly internally, not at all
forward, in marked distinction from Didymictis.
M! have the same cusp structure as in all miacids, but are highly
peculiar in proportions, being very short and wide, markedly tri-
angular, not at all rounded, with sharply emarginate external borders.
These characters are more nearly approached by Viverravus than by
Didymictis but sharply distinguish Ictidopappus from any other
miacid,
Measurements of this specimen are as follows: Length P’, 2.6;
length P*, 4.8; width P*, 3.7; length M!', 3.2; width M}, 5.2; length
M?, 2.0; width M?, 3.7.
Family MESONYCHIDAE Cope, 1875
This family, so widespread elsewhere in the Middle Paleocene and
on into the Eocene, is represented in the present fauna only by two
broken teeth.
Genus DISSACUS Cope, 1881
DISSACUS, species undetermined
U.S.N.M. no. 9692 from the Gidley Quarry is the base of a tooth
with the heel preserved. It agrees in size with M, of Dissacus nava-
jgovius, of the Torrejon, but differs in having a very vestigial basin
internal to the heel crest. Another specimen, from the Gidley Quarry,
is perhaps M,, lacking the anterior portion. The metaconid is very
small and is relatively anterior, as in some species of Dissacus, but the
heel is relatively shorter than in other specimens of that genus known
tome. It is clear that these fragments are mesonychid, and there is
nothing to distinguish them certainly from Dissacus, but they are not
really identifiable.
Order CONDYLARTHRA Cope, 1881
As with most of the major groups here considered, Matthew has
thoroughly reviewed the taxonomic history of the order Condylarthra.
Since, however, I propose a marked change in the current arrange-
ment of the order, an outline of this history must now be given. Cope
proposed the name Condylarthra (then supposed to be a suborder of
Perissodactyla) in 1881, basing it on the Phenacodontidae and princi-
pally on Phenacodus but with Periptychus (‘“‘Catathlaeus’’), Mioclaenus,
and Tetraclaenodon (‘‘Protogonia’”’) probably and Anisonchus possibly
included. Subsequently (1882-1884) the family Periptychidae was
distinguished, but retained in the Condylarthra, the family Menisco-
theriidae was added, and Mioclaenus was excluded, being considered
first an artiodactyl, then a creodont. On the latter point, Scott
(1892) showed that many species placed in Mioclaenus by Cope were
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 217
generically distinct and were indeed creodonts, while Afioclaenus,
sensu stricto, might be a condylarth, in which case it would form a very
distinct family.
In 1895 Osborn and Earle followed Scott’s suggestion and defined
the Mioclaenidae as a family of condylarths. They retained the
three condylarth families of Cope, Periptychidae, Phenacodontidae,
and Meniscotheriidae. They divided the Periptychidae into Anison-
chinae and Periptychinae and stressed the resemblance of the former
to the Mioclaenidae. They also noted that the Periptychidae had
resemblance to the Amblypoda and suggested the possibility of their
belonging there, but left them in the Condylarthra. In one of his
last papers, in 1897, Cope adopted this suggestion and associated the
Periptychidae with the Pantolambdidae in the division Taligrada of
the Amblypoda. In the same year, but with Cope’s paper before
him, Matthew rejected this transfer and adduced new evidence and
reasons for retaining the Condylarthra as a broad group including
Periptychidae, Phenacodontidae, Mioclaenidae, and Meniscotheriidae.
In 1898 Osborn adopted Cope’s arrangement of the Amblypoda, in-
cluding the Periptychidae in the Taligrada and hence excluding it
from the Condylarthra.*! He seems subsequently to have adhered
constantly to the conception of the Condylarthra as including only
the Phenacodontidae, Mioclaenidae, and Meniscotheriidae, and this
authoritative view has since been the most widespread. Matthew
continued for a time to include the Periptychidae but after about 1914
agreed with Cope and Osborn in placing that group in the Amblypoda.
The relationship of the hyopsodonts to this order was not estab-
lished until relatively recently, and even now the conclusive evidence
for it does not appear to be widely known. From the time of its dis-
covery by Leidy in 1870 until 1963 Hyopsodus was universally con-
sidered to be allied to Notharctus, Pelycodus, or similar genera. It
was therefore generally considered to be a primate, occasionally an
insectivore, but in these instances largely on the evidence of supposed
allies, which are in fact primates. In 1903 Wortman definitely dis-
tinguished Hyopsodus from the early lemuroids and referred it, in the
family Hyopsodontidae (defined but incorrectly delimited by Schlos-
ser in 1887 and recognized under an invalid name by Marsh in 1875),
to the Insectivora, on its own characters, not those of lemuroid sup-
posed allies. In 1909 Matthew thoroughly reviewed the Bridger
hyopsodontids, pointed out their resemblance to the mioclaenids, and
suggested that the two families might eventually prove to be synony-
mous. He remarked that they lack diagnostic insectivore specializa-
tions and expressed belief that they are closer to the Condylarthra
than to the more typical Insectivora. Nevertheless, he then placed
%1 He inadvertently cites Osborn and Earle (1895) as Osborn (1892) and gives the impression that the
transfer of the periptychids to the Amblypoda was then proposed.
218 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
them in the Insectivora because of their primitive character and
because of certain marked differences from the phenacodonts.
In 1915 Matthew reviewed the lower Eocene hyopsodonts, which,
for the first time, gave him a good knowledge of their foot structure.
He then considered them to be condylarths, confirming his tentative
suggestion of 1909. He carefully redefined the Condylarthra and
included these five families, the last provisionally: Mioclaenidae,
Hyopsodontidae, Phenacodontidae, Meniscotheriidae, and ?Pleura-
spidotheridae.
In his last contribution (Pale. Mem.) Matthew retained this ar-
rangement, except that the Mioclaenidae and Hyopsodontidae are
reduced by further study to two subfamilies of Hyopsodontidae, as
already tentatively foreseen in 1909.
I now propose to return to Cope’s arrangement of 1884, with the
only change the inclusion of the Hyopsodontidae (with Mioclaeninae),
that is, to his classical conception of a group based on both the phen-
acodonts and the periptychids. It seems to me, after careful and
long consideration with practically all the pertinent original specimens
(including a good deal even unknown to Matthew), that comprehen-
sion of this group has been retarded and taxonomy has been in a
blind alley since the rise in the nineties of the idea of close periptychid-
pantolambdid affinities, an idea to which even Matthew finally sub-
scribed after some years of resistance. This reactionary view, which
at this late date will rather seem radical, requires an outline defense
even though much of the crucial evidence is not drawn from the pres-
ent fauna.
The original suggestion that Periptychus might be an amblypod
(Osborn and Earle, 1895, p. 47) was based on the facts that its tarsus
is not serial and that “it has the strictly trigonal molar of the Ambly-
poda.”’ It may at once be noted that these arguments have since
proved to be valueless. It is now known that the primitive condy-
larth tarsus was not serial, and the molars of Periptychidae are not,
as a rule, strictly trigonal, those of some condylarths are, and the
periptychid molars are otherwise decidedly more condylarth- than
amblypod-like.
Cope (1897, p. 335) stated that he had anticipated that the perip-
tychids, with their astragalo-cuboid contact (nonserial tarsus), might
be the bunodont ancestors of the Amblypoda, but he awaited dis-
covery of their carpus and evidence that it, also, was nonserial. The
carpus had not been discovered, but the continuing failure to discover
any other possible amblypod ancestry led Cope then to assume the
presence of a nonserial carpus in the periptychids and to consider
them as this ancestry. He was also influenced by the suggestion of
Osborn and Earle. This is too theoretical to warrant much con-
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 219
sideration. The periptychid carpus is, in fact, “alternating”, but
so is that primitive for and apparently fairly common among (other)
condylarths.
Osborn (1898, pp. 177-179, 184-186) gives a long list of taligrade
characters as defining that group and common to pantolambdids and
periptychids. The great majority of these are, as he states, primitive
characters. As far as confirmed among the so-called Taligrada by
later research, they are also found to occur among or to be equally
typical of Condylarthra and hence have no bearing on the particular
question here considered. The only progressive taligrade character
given is “molars triangular (tritubercular), selenodont”, which is
decidedly untrue of the Periptychidae and opposed to Osborn’s thesis.
Indeed, I cannot see that Osborn then advanced any actually valid
evidence in favor of the conclusion given, which has since become
taxonomic and phylogenetic dogma, largely on his authority.
Matthew (1897) had already shown that even in the supposedly
typical condylarths, the phenacodonts, the early forms have alter-
nating, not serial, carpus and tarsus and that the Condylarthra there-
fore could not be defined and were not characterized by the mooted
primitive serial carpus and tarsus as had previously been supposed.
He therefore found no difficulty in retaining the Periptychidae in the
Condylarthra and gave a lucid and valid argument for doing so, even
though, as I now think, he minimized his evidence by much over-
stressing the resemblance of the periptychids to the pantolambdids
in limb structure and their difference from the phenacodonts and mio-
claenids in dental pattern.
Upon transferring the Hyopsodontidae to the Condylarthra, Mat-
thew (1915b, p. 311) gave a long diagnosis of the Condylarthra, in-
volving the whole bodily structure. His intention at the time was to
exclude the Periptychidae, since he did so in earlier and later general
classifications, although this point was not then specifically mentioned,
since it was foreign to the fauna he was revising. It is therefore re-
markable and significant that his definition of the Condylarthra clearly
excludes the Pantolambdidae but applies exactly to, and hence includes,
the Periptychidae with a single exception: ‘‘tarsals serial.”” This one
point was, in fact, an error or lapsus, for the forms he explicitly meant
to include do not have strictly serial tarsals, and in some the approach
to the periptychids in this respect is very close.
Matthew’s subsequent defense of the collocation of Periptychidae
and Pantolambdidae was based almost entirely on the limbs, especially
on the astragalus. When evidence drawn from the dentition was at
variance with that drawn from the limbs or astragalus, he almost in-
variably followed the latter. Without quarreling with this principle
of research, it will appear below that the evidence is not necessarily
at variance in the present instance. The dental evidence certainly
220 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
favors condylarth rather than amblypod affinities for the periptychids,
and the limbs might perhaps support either view equally well and cer-
tainly do not oppose condylarth affinities. The recognition of the
affinities of Coriphagus, as discussed under that genus, adds to the
evidence for the opinion supported here.
It has been generally recognized that the teeth of the periptychids
could not give rise to those of pantolambdids or coryphodonts. They
are in fact aberrant and developing along a line, or series of lines, of
their own. It has sometimes been recognized, and can readily be
shown, that their greatest resemblance is with the Condylarthra and
that they could all be immediately derived from types well known in
that order. Indeed, they intergrade with certain mioclaenids to such
a point that the families are difficult to distinguish on this basis. The
pantolambdid-coryphodont dentitions, on the other hand, are widely
different. Union of periptychids and pantolambdids has, then, rested
entirely on limb, and especially on foot structure. Indeed, without
slighting the fact that other resemblances occur, it has depended more
on the astragalus than on any other point. If this arrangement is a
natural one, it seems necessarily to imply that the ‘‘taligrade”’ astraga-
lus and limb structure arose in a stock with extremely primitive teeth
and that the widely divergent periptychid and pantolambdid denti-
tions developed later. Such a thesis seems a priori rather improbable,
but certainly it is not impossible. The apparently, but I think falsely,
analogous case of the divergence of, say, suid and camelid dentitions
after the artiodactyl foot structure arose suffices to demonstrate that
such a history is conceivable.
The analogy is probably false and the thesis indefensible because
in the case of the artiodactyls the teeth, followed back in time, dis-
tinctly converge and are rather plainly derivable from a common type
possessed by animals that already had all the essential artiodacty] limb
characters. This is not true of the periptychids and pantolambdids.
Even within the limits of the Periptychidae there are forms with hardly
any suggestion of the ‘“‘taligrade” foot, but with teeth much too dis-
tinctly periptychid to give rise to the pantolambdids. A common
ancestor, if it existed at all, can hardly have had taligrade feet but
must almost certainly have been a condylarth and a very primitive
condylarth. A review (table 50) of typical astragali of the groups
conceived will make the situation clearer.
These genera are all of about the same age. The Hyopsodontidae
are represented by isolated Gidley Quarry specimens surely of this
group but not exactly determinable, as there are several hyopsodontids
of about this size in the quarry. All five genera have numerous other
characters of the astragalus in which they are closely similar. These
are nondifferentiated primitive protoungulate characters, most of
them disappearing in more advanced forms.
221
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT.
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222 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
All five groups are basically similar in the astragalus. The early
Hyopsodontidae probably are most primitive in this part, and surely
the characters that they share with Tetraclaenodon must be taken as
primitive. From this point of view, Pantolambda is much the most
divergent. Tetraclaenodon and the early hyopsodontids resemble
each other very closely, almost the only differences being the greater
elevation of the crests and excavation of the trochlea and probably
the reduction of the cuboid contact in Tetraclaenodon Both these
characters may be incipient specializations, and both are much em-
phasized in later phenacodonts and not in later members of other
groups. The longer, or relatively narrower, body in the hyopsodontids
is probably of slight significance. Hemithlaeus is very close both to
Teiraclaenodon and the hyopsodontids. Its slightly shorter neck,
almost its only peculiarity with respect to the more primitive con-
dylarths, can hardly be supposed to make this a ‘“‘taligrade” astragalus,
especially as the shortness is only relative and the neck is, in fact,
well developed and typically constricted. The same statement applies
to Periptychus, the neck of the astragalus being about the same in
that genus and definitely more condylarthran than ‘‘taligrade” in
character. All the other characters of the astragalus are condylarth-
ran except that the cuboid facet is about intermediate between the
most primitive known condylarth and amblypod conditions.
Pantolambda has a much more primitive astragalus than Coryphodon,
yet the table clearly shows that it diverges farther from the primitive
condylarthran condition than does Periptychus. This divergence
consists chiefly of the appearance in rudimentary form of characters
greatly emphasized in Coryphodon. Despite the fact that he himself
abandoned it, Matthew’s argument of 1897 in favor of considering
Periptychus as a condylarth and Pantolambda as an “amblypod”
seems to be as valid now as when he wrote it, indeed more so, for he
was not then fully aware of the distinctions between these two genera
now brought out.
Periptychus does, of course, make some approach toward the so-
called amblypods in limb structure, but this is far from reaching
identity, and, being only vaguely or not at all seen in smaller con-
temporaneous allies of Periptychus, may indeed be only convergent
and largely conditioned by size and mode of locomotion. Conver-
gence is the more likely in such forms that have not in any case come
far from a purely primitive type of ungulate limb structure. Similarly
Pantolambda is much more primitive than Coryphodon or other, later
allies in limb structure, but it shows the beginning of the so-called
amblypod type, and the approach is as much toward all or any primi-
tive ungulates as specifically toward Periptychus and its allies. Pat-
terson (1934) has also pointed out that the limb structure of Bary-
lambda tends to link Pantolambda with the coryphodonts.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 223
The later history of the astragalus and feet in general in these
groups is not entirely pertinent but may be mentioned. In the
phenacodonts, culminating in Phenacodus itself, the limbs became
considerably specialized in an inadaptive cursorial direction. Side
toes were moderately reduced, the limbs became or remained moder-
ately slender, and the feet digitigrade, carpus and tarsus serial. The
astragalus differs markedly even from that of the closely allied but
earlier Tetraclaenodon. 'The trochlea becomes very long, the foramen
and emargination are lost, the crests both become high and sharp, and
the head becomes more spherical and loses contact with the cuboid.”
The hyopsodonts were remarkably conservative. As far as we know
them, the limbs of Hyopsodus differed extremely little from those of
its long antecedent Middle Paleocene relatives. An astragalus of
Hyopsodus from the Eocene is almost identical with that of a Paleocene
hyopsodontid here described except for the quite unimportant details
of having the body somewhat less elongate and the head slightly more
spherical. The Anisonchinae and Periptychinae have no known
descendents after this stage (except for a few scraps in the early
Upper Paleocene apparently not generically different from those of
the Middle Paleocene). The amblypod astragalus became very
markedly modified in Coryphodon. Its limbs are highly graviportal
throughout, and the astragalus is profoundly modified and convergent
toward some other graviportal types.
The present conception of this order is as follows: ®
Order CONDYLARTHRA:
Family Hyopsodontidae:
Subfamily Mioclaeninae
Subfamily Hyopsodontinae
group. Small, possibly insectivorous (in habits, not affinities) ani-
mals with simple, low-crowned, bunodont teeth and clawlike unguals.
This longest-lived group is also in almost all respects the least
specialized. Lower Paleocene to upper Eocene. North America.
Family Phenacodontidae: A progressively more cursorial and probably
more strictly herbivorous group, generally analogous within this much
more primitive and nonadaptive radiation to the early progressive ungu-
lates (especially perissodactyls) that replace them in the Eocene. Teeth
brachyodont, becoming polybunous with some slight tendency toward
lophiodonty. Lateral toes becoming somewhat reduced and unguals
flattened into hoofs. Middle Paleocene to lower Eocene. North America,
South America, Europe.
| Members of a persistently very primitive
82 Some of these characters were supposed to be typical of the Condylarthta, because Phenacodus waS
vhe only adequately known genus when the order (or suborder, then) was first defined, and it may seem
strange to consider Phenacodus as a peculiar and in many respects atypical condylarth. It is, in some
sense of the word, technically a ‘‘type’’ of the Condylarthra, but it is definitely not typical throughout.
Taxonomy has many such cases in which a natural group was recognized and named, even though in the
first instance it was largely based on a form later found to be margina! in it.
% Matthew has given excellent diagnoses of all the groups concerned. These characteristizations are
meant to be explanatory, not formally diagnostic.
224 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Order ConpYLARTHRA—Continued.
Family Periptychidae: Characterized by persistently plantigrade feet and by
teeth markedly bunodont, the premolars not becoming molariform (as in
other families) but evolving independently into large swollen crushing
teeth, the molars relatively small, with the primary cusps conical and
crowded together, developing a peculiar type of polybuny especially
in the upper teeth by the development of new cuspules largely internal to
the primary cusps.
Subfamily Anisonchinae: Small and slender forms with the basic dental
characters of this family, but the teeth relatively simple and general
structure apparently closely similar to the Hyopsodontidae. Lower
to Middle Paleocene. North America.
Subfamily Periptychinae: Larger subgraviportal forms developing heavy
limbs and somewhat amblypodlike feet, with complex, polybunous
molars. Lowerto Upper Paleocene. North America.
Family Meniscotheriidae: Hyracoidlike animals of middle size with lopho-
or buno-selencdont teeth, serial carpus and tarsus, and narrow, hooflike
unguals. Their early history is unknown and their relationships doubtful.
They may not be very close to the other condylarths. Their dental evolu-
tion seems to have been in a direction distinct from any other primitive
ungulates, and almost opposite that of the periptychids, but could have
started from a common basis in the Paleocene.
Subfamily Meniscotheriinae: Typical, more lophiodont forms. Upper-
most Paleocene and lower Eocene. North America.
Subfamily Pleuraspidotheriinae: More bunodont forms, of still more
dubious position. Upper Paleocene. Europe.
In the, present fauna the Hyopsodontidae are very abundant and
varied. Phenacodonts are present but are not abundant, being espe-
cially rare in the quarry facies. Anisonchines are not uncommon
but are limited in variety, only two genera and species being recog-
nized, and are much less common or varied than in the Puerco and
Torrejon. The Periptychinae, so common in the San Juan Basin
faunas, appear to be wholly lacking. Meniscotheres are absent, as
would be expected since this group is known only from younger strata.
Family HYOPSODONTIDAE Lydekker, 1889
The small Paleocene animals now believed to be condylarths allied
to Hyopsodus have had a confusing and complex history, which is
here to be sketched only in its more essential points. Cope’s genus
Mioclaenus was at first referred by him to the Condylarthra, but he
later removed it to the Creodonta on the basis of the skeletal characters
of ‘‘Mioclaenus”’ feror. He referred many species to the genus, mak-
ing it a sort of dumping ground for unspecialized dentitions of more
or less bunodont, tubercular-sectorial type. Schlosser, in 1886, sug-
gested that Mioclaenus might really be a condylarth (as Cope origi-
nally supposed). Scott (1892) separated out a number of Cope’s
species and placed them in distinct genera. ‘M/.” feroxr was then
made the basis for the genus Claenodon, a true creodont. Scott then
considered that true Mioclaenus, really allied to the type AZ. turgidus,
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 225
might be a condylarth genus, in which case “it will form a very
distinct family of that order.”
Osborn and Earle (1895) placed Mioclaenus in the Condylarthra
and proposed a new family Mioclaenidae. They discussed only
M. turgidus and evidently intended to include in the family only
Mioclaenus and in that genus only the few species not definitely
removed by Scott. Matthew (1897) hesitated in regarding the Mio-
claenidae as condylarths but did leave them in that group. He placed
in the genus Mioclaenus the species Tricentes inaequidens Cope, which
Scott (1892) had made type of the genus Hilipsodon, and he proposed
a new genus Protoselene for Mioclaenus opisthacus Cope.
In their 1895 paper, Osborn and Earle described a new genus
Oxyacodon, listed as incertae sedis but in the vicinity of the creodonts.
Matthew (1897) left the genus as incertae sedis and transferred to it
Anisonchus agapetillus Cope. In 1914, in a faunal list, Matthew
transferred Oxyacodon to the Mioclaenidae, with a footnote that it
might be a periptychid. In his subsequent work (see Pale. Mem.)
Matthew confirmed the association of Oxyacodon with Mioclaenus
and transferred to it the other Puerco species, “‘Mioclaenus”’ turgi-
dunculus, thus confining the genus Mioclaenus (sensu stricto) to the
Middle Paleocene. He also revived Ellipsodon Scott and placed in
it Mioclaenus acolytus Cope and Mioclaenus lemuroides Matthew.
The arrangement reached by Matthew is thus as follows:
Type: O. apiculatus.
Referred: O. agapetillus, O. turgidunculus, O. priscilla.
Type: M. turgidus.
Referred: M. lydekkerianus.
J Type: E. inaequidens.
|Referred: EH. lemuroides, E. acolytus.
Protoselene: Type: P. opisthacus.
Puerco: Oxyacodon|
M ioclaenus}
=n Etlipsodon
The history of the Eocene group Hyopsodontidae has been suffi-
ciently noticed in connection with the discussion of the Condylarthra
as whole. Matthew early recognized that the hyopsodontids and
mioclaenids were related and in 1909 suggested that future discovery
might result in merging the two supposed families. In his Paleocene
memoir he took this step, retaining the earlier double grouping in the
form of two subfamilies, Hyopsodontinae with Haplomylus and
Hyopsodus and Mioclaeninae with the earlier genera listed above.
After Matthew’s work numerous discoveries of new hyopsodontids
have been made. Jepsen (1930) described Litolestes and Phena-
codaptes from the Upper Paleocene of Wyoming. He placed the
former doubtfully in the Insectivora and the latter doubtfully in the
Artiodactyla, but I have already suggested (Simpson, 1936b) that
they are probably hyopsodontids. Finally there are three new
226 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
genera of hyopsodontids in the present fauna, Haplaletes, Litomylus,
and Litalestes. The number of known genera has nearly doubled
since Matthew completed his work, and the whole unwieldy group
requires reconsideration. The genera now known and considered
hyopsodontid are as follows:
Choeroclaenus (defined below): Type C. turgidunculus. Lower Paleocene.
Oxyacodon: Type O. apiculatus. Lower Paleocene.
Mioclaenus: Type M. turgidus. Middle Paleocene.
Ellipsodon: Type EH. inaequidens. Middle Paleocene.
Protoselene: Type P. opisthacus. Middle Paleocene.
Iitaletes: Type L. disjunctus. Middle Paleocene.
Intomylus: Type L. dissentaneus. Middle Paleocene.
Haplaletes: Type H. disceptatrix. Middle Paleocene.
Litolestes: Type L. ignotus. Upper Paleocene.
Phenacodaptes: Type P. sabulosus. Upper Paleocene.
Haplomylus: Type H. speirianus. Uppermost Paleocene and Lower Eocene.
Hyopsodus: Type H. paulus. Lower to Upper Eocene.
The types and many other specimens of these genera have been
eexamined for the present work ™ in order fully to analyze the affini-
ties of the Fort Union forms here described and their contribution
to knowledge of the family.
In the first instance, generic designations were disregarded and the
18 well-defined Paleocene species referable to this family were graphi-
cally compared by a tabulation of all their known characters.
They were found to fall naturally into groups that correspond very
well with the various genera recognized by Matthew and _ those
defined after his work. The principal characters distinguishing
these generic groups are shown in the following key, which also gives
(in parentheses) the species now placed in each genus, the type being
indicated by an asterisk.
KEY TO THE PRINCIPAL GENERA OF HYOPSODONTIDAE KNOWN IN THE PALEOCENE
I. Paraconids internal, fusing with metaconids; entoconids indis-
tinct, fusing with hypoconulids.
A. P*%, enlarged, inflated, few accessory cuspules.
1. Paraconids less internal, entoconid distinct on M2, few or no
crenulations, M; large, with projecting hypoconulid, M?
with large metacone___________-- Choereclaenus % (turgidunculus*)
2. Paraconids wholly internal, entoconid indistinguishable on
Mz, crests crenulated. M3; much reduced, with rounded
heel. Metacone vestigial on M’________----- Mioclaenus (turgidus*)
%{ Material of Litolestes and Phenacodaptes through the courtesy of Dr. G. L. Jepsen. The American
Museum collections includemostof the types and many excellent specimens of all the generaexcept Phenaco-
daptes. The type specimen of Hyopsodus paulus was not seen, but many good specimens of this and other
species of Hyopsodus were examined.
95 Two or three poorly known supposed species of doubtful status were omitted.
% New genus, defined on p. 232.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 224
B. P44 cuspidate, more or less enlarged but not inflated.
8. Ps without distinct paraconid, metaconid absent or rudi-
mentary, talonid relatively wider, M*; much to somewhat
reduced.
Ellipsodon (inaequidens*, priscus, lemuroides, acolytus, aquilonius)
4. P, with rudimentary paraconid, metaconid relatively large,
talonid narrow, M?’; relatively large___-____-- Litaletes (disjunctus*)
II, Paraconids median to subinternal, not fusing with metaconids,
entoconids distinct, molar talonids basined.
C. Teeth more lophiodont, P, bicrescentic, paraconids distinct,
P4 with metacone, M!~? with strong mesostyle, M’; large.
ee a ee en ee RR eee ee ee Protoselene (opisthacus*)
D. Teeth more bunodont, paraconids reduced or vestigial, no
mesostyles, M*; generally somewhat reduced.
a. Py, without distinct paraconid, but relatively elongate and
trenchant, Ms; large, with projecting hypoconulid, molar
cusps acute.
6. Py with rudimentary metaconid, molar paraconids rela-
tively large_-_-_-- Cxyacodon (apiculatus*, agapetillus, priscilla)
7. Ps with distinct metaconid, with a pit between this and
protoconid, molar paraconids reduced___Litomylus (dissentaneus*)
b. Py with distinct small paraconid but relatively wide and
heavy, M3; somewhat reduced, molars bunodont, generally
broad and low.
8. P, with smaller metaconid and talonid, talonid of Ms; less
elongate, upper molars more transverse and angulate,
outer cusps of P’-4 more compressed.
Litolestes (ignotus*, notissimus)
9. Metaconid and talonid of P, larger, M3; more elongate, P-4
with more conical outer cusps, upper molars rounded and
less-transverses32_ erat tee 8! ees Haplaletes (disceptatrix*)
c. Py elongate, with strong paraconid, M%; reduced, prominent
cingulum descending from protocone tip.
TL ag ah ge i en y= tape Scola gh ee ac a Haplomylus (speirianus*)
Like all keys, this is artificial, but it is based on an extensive analysis
of the characters of all the species listed, and an effort has been made
to select characters that have clear taxonomic value and are probable
or possible indications of phyletic relationships. Thus it is believed
to be probable that the capital letters indicate four natural groups of
genera. The primary division, indicated by Roman numerals, also
appears to me (but with somewhat less probability) to be a natural
dichotomy of the whole group.
Matthew has suggested that Choeroclaenus turgidunculus, which he
referred to Oxyacodon, might be ancestral to one or more species of
Ellipsodon. The resemblance is certainly close, and I believe a
relationship to exist. It seems to me, however, to be that indicated
above by group J and hence more general than he suggested and
inclusive of Mioclaenus, sensu stricto. In more exact phyletic relation-
ship, Choeroclaenus turgidunculus appears to be closer to Mioclaenus
turgidus The resemblance in the molars is as close as to Ellipsodon,
228 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
and the premolars are practically those of Mioclaenus in miniature and
unlike those of Ellipsodon. Furthermore, the rather poorly known
Ellipsodon priscus carries that genus, or something very like it and
probably closely related, back into the Lower Paleocene, contempo-
raneous with Choeroclaenus.
The group of species referred to Hllipsodon is rather heterogeneous,
as discussed under that genus. The presence of so many varied
species shows that several divergent minor phyla are present, but all
appear to be rather closely allied. Hllipsodon priscus represents a
possible an ‘estral type of structure, without being clearly allied to
any particular one of the Middle Paleocene species. The other species
are all approximately contemporaneous and so represent a spreading
out of the group without permitting the discernment of any special
lines of descent.
Oxyacodon represents the second major group in the Lower Paleo-
cene. Its distinctive characters are almost entirely primitive and it
affords a structural ancestry for its general group, D. Itis improbable
that the ancestry of Protoselene would enter into Oxyacodon, and the
case of Haplomylus is also dubious. Upper teeth of Oxyacodon are
unknown, and might considerably modify the present conception of
the genus.
Litomylus very closely resembles Oxyacodon but is in at least two
respects, molarization of P, and reduction of molar paraconids, a more
advanced form. As far as the scanty data go, it could be a relatively
unprogressive descendant of Oxyacodon.
Haplaletes and Litolestes, both possible structural derivatives of
Oxyacodon, are successive, Middle and Upper Paleocene, respectively,
and appear to be close relatives, but they cannot be along exactly the
same line of descent, at least in the known species. Litolestes, the
later genus, is probably more specialized in the reduction of M*; and
perhaps in the more transverse upper molars, compression of P*~*,
and some other details, but its premolars seem to be slightly but dis-
tinctly less progressive than in Haplaletes. (Its known species are
also somewhat smaller than Haplaletes disceptatriz.)
Haplomylus appears at the end of the Paleoce..2 and runs into
the lower Eocene. It is clearly a member of this general group, but
none of the older genera is enough like it to suggest any very close
structural ancestry. Its general premolar and molar structure,
although somewhat more advanced as would be expected, is of the
type of group D of the foregoing key and is such impelling evidence
of relationship that the genus has been classed with that group.
At the same time some important details are not foreshadowed in
any of the other genera. The most striking point, the development
of the posterointernal part of the upper molars as a broad cingulum
sweeping down from the protocone, curiously reminiscent of some
of the ancient primates, is approached (but not very closely) in
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 229
Ellipsodon, but the other characters of the dentition almost exclude
the possibility of special relationship.
Protoselene is a more sharply defined genus than any of the others
here considered. It has the general characters of a primitive hyopso-
dontid but is evidently becoming specialized throughout the dentition
in a way hardly suggested by any other genus.
Hyopsodus is not inserted in the above key, because it is not known
in the Paleocene and because it is so distinctive that it can be recog-
nized at a glance, and confusion with the Paleocene genera is impos-
sible. This distinctive character, however, is entirely in features
demonstrably progressive, and anyone who studies the whole structure
of Hyopsodus, particularly with reference to the evolution that
occurred within that genus, can hardly fail to endorse Matthew’s
conclusion that it is an ally of the Paleocene forms here discussed.
The genera discovered since Matthew’s work still more strongly
substantiate the reality of this relationship, for it may now be said
that Hyopsodus has no known structural character not clearly
developed or adumbrated in the Paleocene hyopsodontids.”
Hyopsodus most nearly resembles group D of the foregoing key,
and in a general way this group has every essential requirement for
the structural ancestry of the Eocene genus. Its most exact resem-
blance in details appears to be with Haplaletes. The sequence
Oxyacodon—Haplaletes-Hyopsodus is, as far as it is known, one in
which no difficulty opposes its acceptance as a structural phylum.
_ There are no ‘‘crossing specializations’, and all characters seem to
be modified uniformly and in one direction in accord with the relative
ages of the genera. At the same time it is, of course, apparent that
the data are inadequate to prove that this is an exact genetic
phylum, and, as in most cases, the probabilities are very much against
our having in collections the exact members of the true line of descent.
There remains for discussion only Phenacodaptes Jepsen, 1930.
This has not been inserted in the key because its affinities with
the other genera are not definitely established, and Dr. Jepsen has
material that he has not yet described and that may give a_ better
basis for decision. - From his published data, the genus appears to
me to enter into the Hyopsodontidae. It has characters strongly
suggestive of the dichobunid artiodactyls, but so has the whole
Paleocene group of hyopsodontids. It is, indeed, almost impossible
to frame a diagnosis, on dental characters alone, that will surely
distinguish hyopsodontids and artiodactyls, yet such skeletal parts as
are known show that they were quite distinct, at least in the lower
Kocene, and even the dentitions give a definite feeling, supported
97 Mile. Friant’s recent reference of Hyopsodus to the Insectivora and strange discussion of the derivation
of insectivore, especially erinaceoid, molar patterns can be quite ignored. She seems to be wholly unaware
of any of the evidence for the true affinities of Hyopsodus.
230 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
by distinctions open to exception but fairly distinctive with the whole
group in mind, that they are different groups. Whether it be con-
sidered as a dichobunid or as a hyopsodontid, Phenacodaptes is a
peculiar form. Yet all its characters known to me are either dupli-
cated or rather closely approached by various hyopsodontids, and its
reference to that group is at least as probable as any other view. The
fact that no artiodactyl, or no other artiodactyl, is known from the
Paleocene in itself carries no great weight as regards the affinities of
Phenacodaptes, except from the point of view of logical procedure in
the special case. If, as seems to me to be true, Phenacodapies re-
sembles a group that is known to have been abundant and varied
when it lived at least as closely as it resembles another that has never
been found in deposits of that age, it seems preferable to refer it to
the former group pending discovery of decisive evidence.
If Phenacodaptes should prove to be a hyopsodontid, it will not
very closely enter any of the categories of the key, not so much that
it has any nonhyopsodontid character as that it is a synthetic type.
The lower premolars are somewhat more suggestive of group J,
although they could well appear also in group JJ. The molar tri-
gonids, as far as I can judge by the data known to me, may be either
Ellipsodon- or Haplaletes-like, probably the former, but the entoconids
are more as in Haplaletes and its allies.
Supergeneric grouping of these forms has always been based on a
separation of Hyopsodus from all other known forms. Historically it
is easy to see how this arose and that it was logical to the point of
being the only arrangement permitted by the data. Hyopsodus is,
within this group, an advanced genus with pronounced modifications,
tending to conceal its relationships to the very primitive forms.
Even within the genus, knowledge was principally based on relatively
late (especially middle Eocene) and specialized species. Further-
more the only Paleocene forms adequately known were from the
Lower and Middle Paleocene and were typified by such a form as
Mioclaenus turgidus, which lies rather far from the structural ancestry
of Hyopsodus.
Kven Matthew necessarily based his conception of the genus on
forms that suggest marked separation from Hyopsodus within the
family. Aside from Mioclaenus he knew only Oxyacodon, Ellipsodon,
Protoselene (with Haplomylus in latest Paleocene and early Eocene).
Oxyacodon is so ancient and primitive that intermediate stages were
necessary to show its probable phyletic position. Ellipsodon now
appears to lie nearer Mioclaenus, at least in its typical species, than
to the more Hyopsodus-like genera. Protoselene is curiously divergent
and not very near any other genus. He regarded Haplomylus as to
some extent intermediate between the earlier forms and Hyopsodus,
and probably this largely influenced him in uniting the Hyopsodon-
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. Zou
tidae and Mioclaenidae, but he saw that Haplomylus could not be
ancestral to Hyopsodus and was not clearly derivative from any
known Paleocene form, so that the evidence was inconclusive.
The discovery, since Matthew, of several Middle and Upper Paleo-
cene genera that are clearly related to Mioclaenus and Ellipsodon but
that approach Hyopsodus much more closely than do those two
genera has much altered the conception of this family. It is now seen
that in the Paleocene there are a less Hyopsodus-like and a more
Hyopsodus-like group. The distinction of the Hyopsodontinae, with
Hyopsodus only, depended in part on progressive characters, sure to
become uncharacteristic when forms of intermediate age and structure
were found, and in part on what appear to be valid phyletic characters
which separate Hyopsodus from one group of Paleocene genera, but
associate it with the other. On present data, it seems preferable to
base supergeneric classification on these latter characters and to draw
the line not between the Paleocene forms and Hyopsodus but between
those of the Paleocene forms that are less and more like Hyopsodus,
grouping that genus with its closer relatives among the older genera.
Subfamilies drawn upon this basis are defined below. This arrange-
ment is still only tentative, and it is clear from the discussion of
generic relationships above that a great deal must yet be learned
before a really well-founded classification within the family will be
possible, but the new arrangement perhaps represents a step toward
thisend. The most doubtful points, as regards the forms now known,
are the affinities of the more atypical species placed in Ellipsodon and
of Litaletes, the true place in the system of the rather isolated genus
Protoselene, that of the apparently aberrant Haplomylus, and the
relationships of Phenacodaptes.
The new evidence substantiates without greatly altering the grounds
for considering the hyopsodontids as condylarths, sufficiently set
forth by Matthew. Discovery of intermediate forms makes the
family more coherent than it seemed to him and improves the evidence
for considering the relatively well known Hyopsodus as indicative of
the affinities of the Paleocene genera, and so strengthens his conclu-
sions. The resemblance of the early hyopsodontids to the dichobunids
in the dentition is so remarkably close that it is difficult to ascribe it
entirely to convergence. Although the known skeletal parts are not
of artiodactyl type, it is quite possible that some branch of the earliest
hyopsodontids did give rise to the Artiodactyla, but this can be proved
or disproved only by further discovery. Even if this should prove
to be the case, the hyopsodontids as a whole would probably be best
classified as Condylarthra, since they had the general characters of
that order, and retained them after the ancestral artiodactyls were
distinctly differentiated in the skeleton.
1192123716
202 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Subfamily Mi0cLAENINAE Matthew (ex ms.) (Mioclaenidae Osborn
and Earle, 1895)
Revised definition.—Paleocene hyopsodontid condylarths with P*,
more or less enlarged and sometimes inflated. P, generally relatively
simple, with small talonid. Molar paraconids reduced, internal,
fusing with metaconids. Molar talonids generally open, entoconids
reduced, fusing with hypoconulid and becoming vestigial. MM’,
often more or less reduced. M!~? with very weak or no hypocone,
posterior cingulum tending to run to tip of protocone.
This subfamily is redefined to include Mioclaenus, its structural
ancestor Choeroclaenus, Ellipsodon, and (doubtfully) Litaletes, and to
exclude Protoselene, Oxyacodon, and some other genera formerly
placed in it. Choeroclaenus does not occur in the fauna here under
discussion, but it 1s defined below because reconsideration of the whole
family demands the proposal of this new name. Ellipsodon and
Litaletes have species in this fauna and are further considered in con-
nection with these species.
CHOEROCLAENUS 88, new genus
Type.—Mioclaenus turgidunculus Cope, 1888.
Distribution.—Lower Paleocene, Puerco, New Mexico.
Diagnosis.—P*, bulbous, inflated. P, without anterior cuspule,
paraconid or metaconid, talonid very small, with one faintly crested
cuspule. Molar paraconids small but distinct, nearly confluent with
metaconids but not wholly internal. Entoconids distinct and about
as high as hypoconulids, molar talonids basined. M4, little or not
reduced. My, with projecting hypoconulid. M!~* transverse, with
sharp external, anterior, and posterior cingula. Hypocone indistinct,
posterior cingulum tending to connect with protocone tip. M? with
well-developed metacone. Conules small, distinct. Cusps low but
sharp and clear-cut, crenuiations and proliferation of minor cuspules
slight or absent.
Discussion.—The type species rather closely resembles the type of
Mioclaenus, M. turgidus, and has almost invariably been referred to
that genus.’ It is, however, sharply distinguished by the characters
given above and in the key on a previous page. Most of these dis-
tinctions are primitive characters, and they tend to link this form,
more nearly than the later and more aberrant Mioclaenus turgidus, to
the small and more generalized early hyopsodontids. Matthew, the
only person who had critically examined the specimens since Cope,
recognized this and recorded it (Pale. Mem.) by transferring the species
to the primitive genus Oxyacodon, a structurally defensible and reason-
%8 Xozpos, pig, + claenus, a combination meant to suggest the dental resemblance to bunodont artiodactyls,
relationship to Mioclaenus, and derivation from the Puerco beds.
% The single exception, previous to Matthew’s last work, seems to be Roger, who placed it in Protogonodon
in his catalog, but the reason for this is not apparent.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 233
able assignment. Our present greatly expanded knowledge of Middle
Paleocene hyopsodontids, however, throws emphasis on certain charac-
ters that now appear to be more important phyletically than those
previously apparent. The premolar inflation is unlike Ozyacodon
both in kind and degree and points toward Mioclaenus, s. s., and not
Ellipsodon. In the lower molars the position, shape, and connections
of the paraconid are very much unlike Oxyacodon and point toward
Mioclaenus and Ellipsodon rather than toward Litomylus and Hap-
laletes (described since Matthew’s death) as does Oxyacodon. The
entoconids are, indeed, distinct, an Oxyacodon-like character, but they
are definitely fusing with the hypoconulid and do not suggest continued
independence as in the group to which Oxyacodon belongs. (No Middle
Paleocene genus known to Matthew belonged to this group, although
it is now richly represented, and so he could not evaluate the impor-
tance of this character.) The upper teeth are not known in true
Oxyacodon, but the characters of the lower teeth sharply distinguish
Choeroclaenus from that genus.
Genus ELLIPSODON Scott, 1892
This genus is revised in Matthew’s memoir. It is unusually varied
in structure, and the species here referred to it increases this variety.
Ellipsodon aquilonius, of this fauna, closely resembles E. acolytus. The
latter is fairly close to H. lemuroides, which in turn approaches £.
inaequidens. There is no logical or convenient separation, probably
of more than specific rank, in this series of four species, yet EL. aqguilonius
is markedly unlike H#. inaequidens, which is the type of the genus.
Whether any generic or subgeneric separation is proper, must depend
on future discovery. At present it seems that the genus may be too
broadly drawn, but this is not demonstrated inequivocably, and it
probably is a natural genus in the sense that the species referred to it
are related to each other.
The type species, HL’. inaequidens, is poorly known. The type speci-
men is a palate with P°-M? of one side or both, all the teeth deeply
worn, and the palate encased in hard concretion. Another palate is
less worn, but even more obscured by concretion, and a third shows
M'~? fairly well preserved. Lower jaw fragments reveal P.-M;. All
the few surely referable specimens were collected by Baldwin for Cope
in 1882 to 1885, and the great collections made subsequently contain
only one specimen possibly referable to the species, and this one is
highly dubious. As far as their localities are recorded, Baldwin’s
specimens all came from Gallegos Canyon, and it is possible that they
are from some local pocket worked out by him or not well exposed
when later collectors visited the area. The unusual circumstance
that the type is the poorest known species of the genus and has not
turned up in new collections for over 50 years makes the status of the
234 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
genus somewhat uncertain. The structure of Py, the extreme reduc-
tion of M;, and perhaps some less clear details are peculiar with respect
to LH. lemuroides or E. acolytus, and the fact that the genus is known
principally from these atypical species may mean that its true nature,
as based on EL. inaequidens, is now seriously misunderstood.
In general aspect, . aquilonius resembles some of its associates.
such as Litaletes disjunctus more than it does Ellipsodon inaequidens,
but in structural detail it seems closer to Ellipsodon acolytus and is
conservatively associated with that species generically (rather than
definitely with the type of Ellipsodon).
ELLIPSODON AQUILONIUS Simpson
Figures 62, 63
Ellipsodon aquilonius Stmeson, 1935d, p. 242.
Type.—U.S.N.M. no. 9280, right lower jaw with P;—M; and alveoli.
Collected by A. C. Silberling.
Paratype —U.S.N.M. no. 9567, right upper jaw with P?—-M?.
Collected by Dr. J. W. Gidley.
Horizon and locality—Types from Gidley Quarry, surely referable
specimens from Silberling Quarry and one, more doubtful, from Loc.
51, Fort Union, Middle Paleocene horizon, Crazy Mountain Field,
Mont.
Diagnosis.—Close to E. acolytus in size and structure, but teeth
generally slightly slenderer, P, relatively shorter and with metaconid
more distinct. M’*; only moderately reduced. PP? without protocone.
M!~? with rudimentary hypocone not connected to protocone apex.
Measurements given below.
Discussion —This is one of the commonest species in the quarries
and is represented by a fine series of specimens revealing its dental
morphology and variation in detail, although in no case is the anterior
dentition preserved.
The number of incisors is unknown. The post-incisive dentition
was complete numerically.
The upper canine and P! are unknown. P? is a small simple tooth
with a small anterior and a larger posterior root. The crown 1s com-
pressed, trenchant, with a median cusp, minute posterior cuspule, and
posterointernal cingulum. P® has three roots but is longer than wide
and has only one distinct cusp, which is central and is triangular in
section, with minute anterior and posterior basal cuspules and a
sharp, continuous, but not cuspidate internal cingulum, stronger on
the posterointernal than on the anterointernal face. P* is wider
than long and has a strong protocone, which is, however, lower than
the amphicone. There is no separate metacone. The amphicone is
triangular and has a sharp posterior and a weak anterior crest from
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 235
the tip. There is a distinct parastyle and small vague metastyle.
The entire crown is circled by a cingulum which bears a cusp, topo-
graphically a metaconule, near the middle of the posterior border.
Aa hs?
hud f
FIGURE 62.—Ellipsodon aquilonius Simpson, U.S.N.M. no. 9280, right lower jaw: a, Crown view; 6, in-
ternal view. Two and one-half times natural size.
FIGURE 63.—Ellipsodon aquilonius Simpson, U.S.N.M. no. 9567, with parts in outline supplied from
U.S.N.M. nos. 9571 and 9576; left upper jaw: a, External view; 6, crown view. Four times natural size.
M' and M? have the same structure but differ in size and proportions.
Although distinct, the paracone and metacone are crested and the
crests tend to form a simple ectoloph. The protocone is crescentic
and its wings bear definite protoconules and metaconules, just internal
to paracone and metacone. There is a sharp, continuous external
cingulum, small definite parastyle, very vague metastyle, and no
mesostyle. The pronounced anterior cingulum stops short at the
anterointernal corner without rising or rounding the long internal
slope of the protocone. The otherwise similar posterior cingulum
236 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
rises toward the protocone apex at the inner end and terminates in a
definite point, a rudimentary hypocone on the posterior protocone
slope and near, but separate from, the protocone tip. M?® is oval,
with rounded corners, and is reduced but much less so than in £.
inaequidens. It has a vestigial but distinct metacone.
The lower canine is known only from its single, cylindrical root,
which indicates a small tooth (but larger than P,) only slightly
procumbent. P, has one small root and a slightly procumbent and
recurved simple crown, excavated on the posterointernal face.
P. is considerably larger, 2-rooted, and with a single distinct heel
cusp. P; is transitional to P, in structure, with the heel considerably
expanded and a curved crest and excavation at the anterointernal
angle. P,, although sharply distinct from the molars, is more nearly
molariform than in any other species referred to this genus. There is
a low distinct metaconid on the posterointernal protoconid slope, at
about two-thirds of the distance from the base to the apex of the crown.
The anterointernal protoconid slope is excavated, and the anterior
protoconid crest curves inward and then posteriorly around it, gener-
ally without forming a cusp but in a few specimens with a very rudi-
mentary and low paraconid. The talonid has a slight crest ending
in a cusp at the posterior margin, somewhat external to the midline,
with a vague, open internal basin and a small posterointernal cuspule.
M, has the protoconid and metaconid opposite, the metaconid
slightly the larger of the two. The paraconid is distinct, fully
internal, partly connate with the metaconid, and smaller and lower
than the latter. The talonid is nearly as high as the trigonid and is
well basined, but with the basin open in a narrow notch between
entoconid and metaconid. The hypoconid is large, distinct and
crescentic. The small hypoconulid and larger and equally high
entoconid are poorly separated. When quite unworn, three small
cuspules are seen, one on the anterior hypoconid wing, one on the
posterior metaconid slope, and one on the anterior entoconid crest.
The talonid is wider than the trigonid. Mg is similar to M;, but the
trigonid is larger, absolutely and relatively, and is as wide as or wider
than the talonid. The entoconid is reduced in size, in height, and in
distinction and the talonid basin more open. Mg is reduced, the
trigonid decidedly the widest part of the tooth, the entoconid indis-
tinct, and the hypoconulid large and sharply projecting as a well-
defined spur.
U.S.N.M. no. 9686 preserves dm,. Its talonid closely resembles
that of M, but is smaller. The trigonid is much more elongate and
narrow than on the permanent molars, and the paraconid is larger
and well separated from the metaconid.
The horizontal ramus is slender, with a long symphysis, which
seems not to have fused even in old age. The posterior mental
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. Ie
foramen is generally beneath the posterior end of P,; or anterior end
of Py. The coronoid process seems to have been high and broad.
The masseteric fossa is shallow and simple, its only sharp boundary
anterior. The angle is poorly preserved but evidently was rounded
and not sharply projecting. The dental foramen is about on a level
with the alveolar border. The condyle is elevated well above the
teeth and its transversely oval, gently convex articular surface faces
equally posteriorly and superiorly.
The infraorbital foramen is above P*, and the zygoma arises chiefly
above M?”.
The statistical constants of the principal tooth dimensions are given
in table 51, based entirely on the sample from the Gidley Quarry.
TaBLE 51.—Numerical data on upper and lower dentition of Ellipsodon aquilonius
Variate N R M o V
(iP ees ery ay cect: 10 2. 8-3.5 | 3.22+0.06 | 0.19 +0. 04 6.0+1.3
\ileh ne eee eae ee 10 1. 7-2. 1 | 1. 88+0. 03 | 0. 108+0. 024 3. 740. 8
Uh] Bp etic yet ae a 1 3. 2-3. 7 | 3.4140. 05 | 0.16 +0. 04 4.6+1.0
\W ee ae ea 11 2. 1-2.5 | 2.3140. 04 | 0. 116+0. 025 5.0+1.1
LM ae Ss oa ae 19 3. 1-3. 6 | 3. 40+0. 03 | 0. 14340. 623 4.2+0.7
TI Dep eae le ele 19 2. 7-3.2 | 2.90+0. 04 | 0. 172+0. 028 5.9+1.0
Vistas cio seers = 28 3. 1-38. 9 | 3.58+0. 03 | 0. 17940. 024 5. 0O+0. 7
VA ig es ae ee 29 2. 8-3. 6 | 3. 30+0. 04 | 0. 19040. 025 5. 8+0.8
TAN ey ga ge apd 24 3. 5-4. 1 | 3.82+0.03 | 0. 134+90. 019 3.540. 5
WAM. grate th 24 2. 4-3.0 | 2. 75+0.03 | 0. 16140. 023 5.8+0.8
DD EREAS a Sea eee a 6 3. 1-3. 3 | 3.2340. 03 | 0. 07540. 022 2.340. 7
We Seee eer 7 2. 5-2.9 | 2.7140. 06 | 0.15 +0. 04 5.44+1.4
Up semete et pee be 7 3. 0-3. 2 | 3. 1140. 024! 0. 06440. 017 2.1+0. 6
AWG REL ie ee ae poy a of 3. 8-4.1 | 3.9640. 04 | 0.12 +9. 03 3.0+0.8
TEIN Uae ge el satarplen 10 3. 1-3. 4 | 3. 21+0.03 | 0. 104+0. 023 3. 30+0. 7
VV ie 2 a SROs ae 10 4.1-4.5 | 4.29+0.05 | 0.14 +0. 03 3.4+0. 8
Ie eee 13 3. 1-3. 7 | 3.4340. 05 | 0.17 +0. 03 4.9+1.1
WaViz eine Sie anne 13 4.9-5.4 |] 5.20+0.05 | 0.17 +0. 03 3.2+0. 6
TE LNs eee ee 8 2. 3-2.6 | 2.40+0. 04 | 0. 100+90. 025 4.2+1.0
Weiser mi g 3. 5-4. 1 | 3. 7140.07 | 0.21 +0. 05 5.6+1.3
Despite the fact that the sample probably includes both sexes and
certainly includes teeth in many different stages of wear, the figures
are very consistent and show remarkably little variation. The high-
est V is only 6.0 and the average is 4.35. The consistent distribution
of the V’s is also striking, for of the 20 values only two differ from
the average by as much as twice the corresponding standard error.
The two exceptions (for length of P? and length of P*) are based on
scanty data and are abnormally low values, 2.3 and 2.1.
The unusually adequate sample of E. aquilonius from the Gidley
Quarry and the presence of seven lower jaws apparently of the same
species from the Silberling Quarry afford the best opportunity to
detect any minor differences that might occur between these two
horizons and localities. The possible association of morphological
238 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
variants with one locality or the other and possible differences in
mean dimensions have been carefully compared. The greatest differ-
ence in mean dimensions is only 0.2 mm (for width of P3), which is
not shown to be significant (it being mathematically demonstrable
that a difference as great would arise in random sampling of a homo-
geneous sample about once in 20 trials or oftener). The other differ-
ences are far from any probable significance. Only one specimen
from the Silberling Quarry falls outside the observed range for the
Gidley Quarry in a single dimension, having M, 3.8 mm in length,
but this is far within the probable range of the Gidley Quarry popu-
lation, the deviation being only 1.4 times the standard deviation.
It is unnecessary to give the results of the numerous other detailed
comparisons made, since all were negative, showing no significant
difference between the samples from the two quarries. Since the
samples are so good, this warrants the positive affirmation that a
single race of this species occurs in both quarries.
A single specimen from Loc. 51, U.S.N.M. no. 9709, a lower jaw
with M, and broken M,, has these two teeth above the average size
for the Gidley Quarry sample, but within the range of the latter.
ELLIPSODON species
U.S.N.M. no. 9662, from Loe. 18, is a partial right lower jaw with
Py. This tooth resembles that of Hllipsodon aquilonius but is rela-
tively higher, the paraconid is more distinct, and the length, 4.2 mm,
is significantly greater than in that species (d/o=4.9), although the
width, 2.6 mm, is not (d/s=2.5). This is probably another species,
but the material is inadequate for its exact determination.
Genus LITALETES Simpson
Litaletes Stmpson, 1935d, p. 242.
Type.—Lutaletes disjunctus Simpson.
Distribution —Middle Paleocene, Fort Union, Montana.
Diagnosis.—P, with bladelike main cusp, distinct paraconid and
relatively large metaconid, talonid small with narrow, rudimentary,
open basin. Molar paraconids distinct, small, internal. Entoconids
indistinct, fusing with hypoconulids, especially on My. P* with rudi-
mentary metacone, strong metastyle. M?!~° with distinct hypocones.
M:’; not reduced, M? with strong metacone.
Discussion.—This genus is very distinct from Ellipsodon, but
Litaletes disjunctus and Ellipsodon aquilonius do not differ very
greatly. It could hardly be supposed that Ellipsodon inaequidens,
type of that genus, is congeneric with Litaletes disjunctus, for their
whole adaptive tendency seems different, and each tooth has definite
and pronounced structural distinctions. The question then is not
whether Ellipsodon and Litaletes are distinct genera, but where the
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 239
more or less transitional Ellipsodon aquilonius belongs. It is closer
to Ellipsodon acolytus than to Litaletes disjunctus or any other species
known to me, and, as already stated, that is the reason for referring
it to Hllipsodon at present. It is, however, probably closer to Lita-
letes disjunctus than to Hllipsodon inaequidens. Perhaps it will be
necessary to transfer /. aquilonius and E. acolytus to Litaletes at some
future time, but that introduces a great difficulty as regards the
generic position of E. lemuroides, and for the present the system
adopted here seems equally natural and more convenient.
LITALETES DISJUNCTUS Simpson
Fiaurss 64, 65
Litaletes disjunctus Simpson, 1935d, p. 242.
Type.—vU.S.N.M. no. 9323, right lower jaw with C—M; (M; broken).
Collected by A. C. Silberling.
Paratype—U.S.N.M. no. 9324, right upper jaw with P%—M?.
Collected by A. C. Silberling.
Horizon and locality —Gidley Quarry, Fort Union, Middle Paleocene
horizon, Crazy Mountain Field, Mont.
Diagnosis.—Sole known species of genus. Measurements given in
table 52.
Discussion. —P** and M! of the species are now known only from
the paratype, so that their variation is not established. On this
specimen both P’ and P* have distinct parastyle and metastylie and
on both the posterior amphicone crest bears a rudimentary metacone,
largeron P*. P*hasarudimentary protocone. On P* the metaconule
is not developed on the cingulum but more normally, on the protocone
wing, and the cingulum does not cross the inner face of the protocone.
On M!* the parastyle is unusually prominent and the hypocone is
larger than in Ellipsodon aquilonius and not so near the protocone
apex. M® is less reduced, less oval, and the metacone, although
smaller than the paracone, is large and distinct.
TABLE 52.— Available numerical data on lower teeth of Litaletes disjunctus from the
Gidley Quarry
Variate N R M =(d)?
| [jd BAS = sx SS SAE URE aa Sees Sis a 3 3. 3-3. 5 Sell 0. 0267
Vi der! Leas Ae Te a ot 0 ERE ae fet nae re 3 1. 9-2. 1 2. 00 0. 0200
lib, ss ets Se Ee Oe Et ieee ee 5 3. 5-3. 9 3. 68 0. 1080
VOY TP aoe spre: NONE AS ine eae TURN ESS. 5) 2. 4-2. 8 2. 54 0. 1120
a Vinmeeearsatee ed CP ea ee 0 3. 9-4. 2 4, 07 0. 0743
VIAL ie 2 Sete ee, Role REI St ne OY Oa Py SRR 5 3. 2-3. 5 3. 30 0. 0890
LEN Ti este es oe en er aie 6 4, 3-5. 2 4. 67 0. 5134
WIM [pp kaos oe Sek Be ee ees ee 5 3. 7-4. 5 4, 04 0. 3520
TE iM open Sven's Sie ene Se ene Say ae gE 3 5. 0-5. 3 op als} 0. 0467
NI ING lye i a i a peed ees. 2 as 4 3. 3-3. 8 53 ts 0. 1700:
240 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
f Sank
}
Liles nN i}
me
FIGURE 64.—Litaletes disjunctus Simpson: a, U.S.N.M. no. 9281,
right Py-M3, crown view; 6, U.S.N.M. no. 9323, right lower
jaw, external view; c, U.S.N.M. no. 9338, right lower jaw,
internal view. ‘Twice natural size.
FIGURE 65.—Litaletes disjunctus Simpson, U.S.N.M. no. 9324,
right upper jaw: a, External view; 0, crown view. Three
times natural size.
The lower canine is a
small but tali, erect, spat-
ulate tooth. P, is low,
l-rooted, with a minute
heel. P._3 are more ad-
vanced than in Ellipsodon
in that each has a distinct
paraconid. The heel is,
however, relatively short,
and only half its width is
formed by the incipient
basin. The anterior blade
of the protocone is dis-
tinctively modified into
a sort of shearing crest.
The lower molars close-
ly resemble those of Hlip-
sodon aquilonius, but My
has trigonid and talonid
of nearly equal width,
M, has trigonid generally
markedly wider, and M;
is less reduced.
U.S.N.M. no. 6179 from
Loc. 51, includes an M,
morphologically compa-
rable to this species and
measuring 4.7 by 3.9 mm,
near the means for the
Gidley Quarry specimens.
There is, however, an
upper jaw with M?~* from
the same locality, dimen-
sions given in table 53,
that is morphologically
very close to this spe-
cies but notably smaller
than the available Gid-
ley Quarry specimens.
Since, however, these are
only two in number it
cannot be assumed that
a real difference exists.
The greatest relative dif-
ference, in length of M?’,
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 241
does not necessarily imply a coefficient of variation higher than 5
on the hypothesis that a single species is present, and this is a very
moderate degree of variation for one species.
TaBLE 53.— Measurements (in mm) of available upper teeth of Litaletes disjunctus
P3 Ps Mi! M2 Mi
U.S.N.M. no.
L Ww L WwW L W L lel ered by WwW
9324:(Gidley/Quary) == =22 22. 2-3 3.4 2.8 33 4.4 3.9 5.0 4.6 6.2 3.6 5.3
Phsza(GidleysOuarry) ae ae I eh ree Oe Se 4.8] 6.5] 3.4 5.6
HEU sooty Se ae | Bem a | pele | bln £0( 66) 30 Rd
Subfamily HYOPSODONTINAE Trouessart, 1879 !
Revised definition——Paleocene and Eocene hyopsodontid condy-
larths with P*,; not inflated, generally moderate in size, cuspidate,
somewhat molariform but never exactly so, P, generally with a meta-
conid and wide but imperfect talonid basin. Molar paraconids
median to subinternal, not fusing with metaconids, entoconids dis-
tinct and high, talonid basins closed. M®%, little or not reduced.
M!~? with definite hypocone, small in earlier and large in later forms,
sharply distinct from tip of protocone.
Remarks.—Aside from the type genus, I place here Oxyacodon,
Litomylus, Litolestes, and Haplaletes with some assurance, Protoselene
and Haplomylus very doubtfully. Litomylus and Haplaletes represent
the subfamily in the present collection.
Genus LITOMYLUS Simpson
Litomylus Stimpson, 1935d, p. 243.
Type.—Litomylus dissentaneus Simpson.
Distribution.—Middle Paleocene, Fort Union, Montana.
Diagnosis.—P, trenchant, paraconid rudimentary, metaconid dis-
tinct, separated from the protoconid by a small pit. Molar cusps
rather bunodont but acute, paraconids reduced and median, M’*;
little reduced, hypoconulid of M3; sharply projecting. Hypocones of
M!* relatively large and internal. M®* transverse, triangular.
LITOMYLUS DISSENTANEUS Simpson
FiGure 66, 67
Litomylus dissentaneus Stmpson, 1935d, p. 243.
Type.—U.S.N.M. no. 9425, left lower jaw with P;-M;. Collected
by A. C. Silberling.
1 “Hyopsodinae”’ in the original publication, but the emendation can hardly be claimed to change
authorship.
DAD BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Horizon and locality —Gidley Quarry, Fort Union, Middle Paleocene
horizon, Crazy Mountain Field, Mont.
Diagnosis.—Sole known species of genus. Dimensions given ir
table 54.
Discussion.—This is the rarest of the four species of hyopsodontids
in the quarry, but it is distinctive and fairly well known.
FIGURE 66.—Litomylus dissentaneus Simpson, U.S.N.M. no. 94235, left lower jaw: a, Crown view; b, internal
view. Four times natural size.
=>
EV
i
tr
cy) >
RY »
\ b
wy ui
FIGuRE 67.—Litomylus dissentaneus Simpson, U.S.N.M. no. 9557, with tooth in outline from U.S.N.M.
no. 9580, right M!-3: a, External view; b, crown view. Four times natural size.
No upper teeth anterior to P! are known, and P* is represented only
by an uncharacteristic fragment. M'~? have sharp, subequal, nearly
conical paracone and metacone. The protocone is likewise sharp and
smaller than in the other species of this group. The conules are large
and equal. The external cingulum is sharp and even forming equal
angulations, rather than distinct cuspules, at the parastylar and meta-
stylar corners. There is no mesostyle. The hypocone is larger than
in any known contemporaneous species and is quite distinct from the
protocone and equally internal, but smaller. M°* is markedly trans-
verse and is triangular, not rounded or oval, without a hypocone but
with a sharp, distinct metacone.
P 3_, are long, low, narrow, trenchant teeth, unlike any others known
in this family. Each has a rudimentary, median, basal paraconid.
The talonids are poorly developed in each case and have only a single
posteromedian cuspule and a very rudimentary posterointernal basin.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 243
The sharp posterior protoconid crest bears a very slight thickening or
cuspule. The anterointernal region is somewhat excavated and has a
cingulum below it. P3 has no metaconid, but P, has a small papilla
about halfway up the crown, and above and external to it, between it
and the protoconid apex, is a small pit or pocket.
The lower molars, with their acute, well-separated major cusps,
resemble those of Oxyacodon. The paraconids are vestigial, forming
a small shelf or crest connected with the anterior protoconid wing
but not with the metaconid. On M, this nearly reaches the inner
border, on M; it is submedian, and on M; fully median. Protoconid
and metaconid are of nearly equal size. The heels are well basined
and the entoconids are sharp and distinct, nearly as high as the
hypoconids and on M,-, larger and higher than the small hypoconu-
lids. On M; the hypoconulid is as high as the hypoconid and projects
sharply posteriorly.
Only five specimens, ail from the Gidley Quarry, are recognized as
of this species. Measurements are given in table 54.
TaBLE 54.—Jndividual measurements (in mm) of upper and lower dentition of
Litomylus dissentaneus
P3 P, Mi M2 M3
U.S.N.M
no.
L W L WwW L WwW L W L W
9425 eee ee ee eee 33 14 3.5 1.9 2.9 2.4 3.0 27 352 252
OST See o ons 22s oo 5 Son eee |e Se ee eS ees ha 2.9 21 3.0 225 3.4 2.2
ih a 3.6 1.6 3.9 BY,
M! M? M3
U.S.N.M. no.
L W L WwW L WwW
BD fete Oe Stoo oe se. Slee ee eh st ooo oe 3.2 4.2 3.3 4.7
RS ai a5 Se ee nes ee ee ee eee 2.9 3.9 3.2 4.5 2.6 4.1
Genus HAPLALETES Simpson
Haplaleies Simpson, 1935d, p. 243.
Type.—Haplaletes disceptatriz Simpson.
Distribution.—Middle Paleocene, Fort Union, Montana.
Diagnosis.—P, not trenchant, with distinct paraconid and meta-
conid and relatively large basined heel. Molars bunodont, cusps
rather rounded and low. Paraconids reduced and median. M3
somewhat reduced, hypoconulid of Ms; slightly projecting, markedly
less than in Litomylus. Amphicones of P?-* more rounded than in
Litolestes. P* with rudimentary metacone. Upper molars rounded.
Hypocones of M!~? distinct, but smaller than in Litomylus. M® less
transverse and more rounded.
244 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
HAPLALETES DISCEPTATRIX Simpson
Fraurss 68, 69
Haplaletes disceptatriz Stimpson, 1935d, p. 244.
Type.—U.S.N.M. no 9500, right lower jaw with P;-M;3. Collected
by A. C. Silberling.
Paratype —U.S.N.M. no. 9555, right upper jaw with P?-M?. Col-
lected by Dr. J. W. Gidley.
FIGURE 68.—Haplaletes disceptatrix Simpson, U.S.N.M. no. 9500, with parts in outline supplied from
U.S.N.M. no.5,9600, right lower jaw: a, Crown view; 6, internal view. Four times natural size.
TC
WW
cfN:
FIGURE 69.—Jlaplaletes disceptatrix Simpson, U.S.N.M. no. 9555, right upper jaw: a, External view;
b, crown view; c, internal view. Four times natural size.
Horizon and locality—Gidley Quarry, Fort Union, Middle Paleo-
cene horizon, Crazy Mountain Field, Mont.
Diagnosis.—Sole known species of genus. Dimensions in tables]55
and 56.
Discussion.—This delicate little species is the smallest condylarth
in the quarries, and only Litolestes includes smaller known species in
this order.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 245
TaBLE 55.—Principal available numerical data on lower dentition of Haplaletes
disceptatrix, all from the Gidley Quarry
Variate N R M = (d?)
Lg) PO oes 2 RN is MR ee Peg ee ane Sr oe 3 2. 1-2. 3 252.0 0. 0200
VE eee pace we rete area re en II 3 Teel 1. 40 0. 0200
Ji) yee gk ee se SRB OE EES alee eee bec Bbw em 2 D5 Dey 0
AA eee eee « ae RR ey eee ee 2 1. 6-1. 7 1. 65 0. 0050
TEI Cos, cg 2k nd a Sie eee i ian Me 4 2. 4-2. 6 2. 48 0. 0276
AVA IG EE RSE ERE ON Ee hee Path 2 8 4 2. 1-2. 3 DANS 0. 0276
TAY Los TRS Oe ee oe Sper Lect 6 2. 4-2. 9 2.65 0. 1350
VAIN Geese ees, Meet eee ee a 6 2. 3-2. 7 2) oil 0. 1066
IL) Nilcs: el ee etn ABA Bee Oe, COLE ot peg USES RE 6 2. 6-2. 9 2. 80 0. 9800
VESTN Ub a I et oO 6 2. 2-2. 4 Desi 0. 0286
TABLE 56.— Measurements (in mm) of the two available upper dentitions of Hapla-
letes disceptatrix, both from the Gidley Quarry
P? ps Ps M! M3 M!
U.S.N.M. no.
L W L W L W L WwW L W L Ww
Cte ee ee 1.5 Vat 22 2.1 2.4 2.9 2.4 3.2 2.6 3.7 1.9 3.1
Q55 Gee ee Bees Be re ee ES ere a PN eee 2.5 3. 1 2.9 Ould:
P? is a small simple tooth resembling an anterior lower premolar.
P? is peculiar in having a low and small but sharp and distinct proto-
cone. P? ‘resemble those of Litaletes in their rudimentary metacones,
but the metastyles are less developed, and P* has no metaconule. The
upper molars are similar to those of Litomylus, but are more rounded
in contour and have the hypocones of M'~? smaller.
P; has a distinct paraconid and a heel about as well developed as that
of P, in most contemporaneous species. P, has definite paraconid
and metaconid and a wide, large, basined heel with two posterior
cusps. The lower molars resemble those of Litomylus, but the crowns
are lower, the cusps blunter, and the internal cusps more distinctly
elevated over the external. The talonid of M; is less elongate.
Family PHENACODONTIDAE Cope, 1881
Most of the manuscript notes left by Dr. Gidley refer to this group,
and it was evidently his intention to publish a preliminary paper on
it. There are three different drafts of part of his brief account,
evidently written at different times and in part not consistent with
one another. The draft that seems to be most recent is still incom-
plete and has still later memoranda written on it for other changes
that were never made. The integral publication of this manuscript
is impossible, as it does not form a connected whole and does not fairly
246 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
represent the final opinions of Dr. Gidley. I have, however, quoted
parts of the manuscript directly, have mentioned some other of Dr.
Gidley’s opinions in indirect quotation, and have used his manuscript
names and followed his disposition of the specimens as far as possible.
The material has been much increased since Dr. Gidley’s study of
it, but it is still rare. He tentatively identified only 8 specimens, and
11 have since been collected (3 for the National Museum and 8 for the
American Museum). This family is abundant in the Torrejon, and
also in the lower Eocene, but it is extremely rare in the quarries in
the Crazy Mountain Field and can be considered as common only at
one surface locality, no. 25, from which 11 specimens have been
obtained.
In the Torrejon the only genus of this family is Tetraclaenodon.?
It is there very abundant and highly varied and has therefore received
numerous specific names, but from Matthew’s work it seems probable
that only two valid species occur in the Torrejon: TYetraclaenodon
puercensis, a larger, more common, and varied form, and T. pliciferus,
a smaller, rarer, and perhaps less varied species.
In the Crazy Mountain Field, also, there are indications of two
species, one of about the size of 7. puercensis, but very rare and not
exactly identifiable, the other smaller, although generally larger than
T. pliciferus. There is also a second genus, Gidleyina, apparently
characteristic of the higher levels in this field.
TETRACLAENODON Scott, 1892
TETRACLAENODON SYMBOLICUS Gidley
Fiaurss 70, 71
Tetraclaenodon symbolicus GipLEY, Simpson, 1935d, p. 239.
Type.—U.S.N.M. no. 6169, part of right lower jaw with M, and
alveoli of P3.4 and My. Collected by A. C. Silberling.®
Paratype.—U.S.N.M. no. 6168, jaw fragment with right M,_,, and
a separate left P, probably this species but probably not associated.
Collected by A. C. Silberling.
2 This genus is still often called Hwprotogonia. It was originally described as Prologonia Cope, 1881. Cope
later considered this as preoccupied by Protogonius Hiibner, 1816, and replaced it by Ewprologonia Cope,
1893, the type of both being P. (or H#.) subquadrata. In the meantime Scott had proposed the genus Teira-
claenodon Scott, 1892, for Mioclaenus floverianus Cope. Scott did not recognize the relationship, but his
Tetraclaenodon was certainly the same genus as Protogonia Cope, and it therefore includes as a synonym
Euprotogonia Cope. Matthew in 1897 preferred Euprotogonia Cope, 1893, to Tetraclaenodon Scott, 1892, on
the ground that the latter was based on an error, and through Matthew’s work Euprotogonia became the
familiar name for the genus. Matthew later recognized that his action had been invalid, and he used the
name Tetraclaenodon in all his more recent work. Now Cabrera (1935) has insisted that Protogonius Hiibner
does not preoccupy Protogonia Cope, since they differ in termination, and he calls the genus Protogonia.
Without taking a decisive stand, I shall tentatively continue to use Tetraclaenodon, which has the cardinal
virtue of being generally and correctly understood and of being unambiguous. Huprotogonia is certainly
invalid, and Protogonia is of dubious validity, is ambiguous, and is unfamiliar to present-day students.
3 IT retain this specimen as type, since it is clearly that intended by Gidley. No. 6168, here made paratype,
would be a better type.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 247
Horizon and locality.—Type from Silberling Quarry, paratype from
Loc. 25, about 250 feet lower stratigraphically, Fort Union, Middle
Paleocene horizon, Montana.
FIGuRE 70.—Tetraclaenodon symbolicus Gidley, FIGURE 71.—Tetraciaenodon symbolicus Gidley;
U.S.N.M. no. 6169, right lower jaw (with M)): a, a, U.S.N.M. no. 6168, right Mi-2, crown view;
Crown view; 6, internal view. One and one-half a’, same internal view; 6, Princeton Univ. no.
times natural size. 13757, right M23, crown view. One and one-
half times natural size.
Diagnosis.—Gidley: ‘‘This species is smaller than FE. [Tetraclaenodon,
G. G. S.] puercensis, being about intermediate in size between that
species and FE. minor [= Tetraclaenodon pliciferus, G. G.S.]. The
lower molars are proportionately narrower transversely than those of
the former species,* and the lower jaw is much shallower. This last
character may be due in part, however, to a less mature condition of
the specimen, which represents a young individual with the first true
molar just coming into use.» The striking similarity in detail of the
lower molars with those of E. [T., G. G. S.] puercensis is a notable
feature of the species and separates it clearly from EH. minor [T.
pliciferus, G. G. S.].. The more notable points of similarity are the
slight roughening and wrinkling of the enamel surface and a tendency
of the lophs of the teeth to break up into small cuspules.”’ ®
Simpson: Intermediate between TJ. pliciferus and JT. puercensis in
size, but nearer the former both in size and in structure. The only
constant difference from T. pliciferus is the greater size, inadequate
for specific differentiation were it not constantly correlated with the
4 And within the range of T. pliciferus in this proportion.—G. G. S.
5 A specimen of T. pliciferus of comparable age has a deeper jaw, despite its smaller teeth but a referred
specimen of T. symbolicus also hasa deep jaw. Thisis probably a highly variable character, and also depends
on crushing to a considerable degree.—G. G. S.
6 From figures of the Torrejon specimens this would seem a striking and good distinction, but the speci-
mens themselves show that 7’. pliciferus also has wrinkled enamel and a tendency for lophs to break up into
cuspules. These may be functions of size, to a limited extent, and slightly less pronounced in T’. pliciferus
than in T. puercensis. T. symbolicus is about intermediate between the two in these characters, as in size.
119212—37——_17
YAS BULLETIN 169, UNITED STATES NATIONAL MUSEUM
widely different geographic distribution, as far as known. Crenula-
tions possibly slightly more developed and paraconid weaker on type
and paratype of 7. symbolicus, but these are variable characters and
other specimens suggest that they are not of specific value.
Discussion.—This species seems to be variable, and it is difficult to
separate it from 7’. pliciferus, with which it must be closely related.
Its smallest variants, indeed, could not be separated from T. pliciferus
were they found together, but the homogeneous sample from Loc.
25 averages larger than 7’. pliciferus. Since all these individuals are
from one horizon and locality they evidently represent either one
herd or an actually interbreeding stock, the character of which is thus
slightly different from the Torrejon species and may be given taxo-
nomic distinction. The size difference is statistically significant. I
therefore accept Dr. Gidley’s species, but consider it as much closer
to T. pliciferus than he believed.
It happens that the type and to less degree the paratype have the
enamel unusually crenulated and the paraconids small, characters
slightly closer to 7. puercensis than to T. pliciferus, although those
species intergrade in this respect. The other specimens from Loc.
25, however, have the enamel somewhat smoother and the paraconids
more distinct, almost exactly as in T. pliciferus.’
The more recently discovered specimens include one with dm,,
representatives of all the lower molars and of P, and Py, and also
M?*. These are all morphologically within the range of 7. pliciferus.
They might be grouped into three subdivisions, large, medium, and
small, but I think the grouping would be subjective and that the
variation is individual and approximately normal.
TABLE 57.—Numerical data on lower molars of Tetraclacnodon symbolicus
Variate N R M o V
Mg ent Sie ek 6 7.4-7.9 | 7.6340. 07 | 0. 18+9. 05 2.4+0.7
AWi Nie es Se 6 5. 6-6. 6 | 6. 2340.13 | 0.3140. 09 5. 0+1. 4
HN ig aercesee 2 saees Le 6 7. 5-8.2 | 7.77+0. 10 | 0. 24+0. 07 3. 0+0. 9
Wiig I Ge 6 6. 2-7.0 | 6. 75+0. 12 | 0. 30+0. 09 4,5+1.3
ORY Es ae 6 7.3-8.1 | 7. 7040.10 | 0. 25+0. 07 3.340. 9
WiAVIg Stk ae ea 6 5. 2-5. 7 | 5.87+90. 08 | 0. 20+0. 06 3.8+1.1
The available material (including that in the American Museum)
provides only six well-preserved examples of each of the three lower
molars, and it is not entirely homogeneous since the type and one
other specimen (as given below) are not from Loc. 25, whence all other
7 One of the most extreme specimens in this respect, U.S.N.M. no. 6167, was referred to 7. symbolicus by
Gidley, in his notes, so that his conception of the species was the same as mine despite the differences in the
diagnosis,
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 249
specimens were derived. Nevertheless the material is well unified,
and data on it can be more adequately summed up in statistical form
than otherwise. (Table 57.)
The dimensions of the two specimens not from Loc. 25 are given
in table 58.
TaBLe 58.—-Individual measurements (in mm) of lower molars of Tetraclaenodon
symbolicus
M; M2 M3
U.S.N.M. no. ——_———_____—_—
L W L WwW L WwW
GG OS ae ot a ee eee 7. 9 6.3
OOD jee sere: Dee ie ES eee Co OF. | eaten a ee eee Co Tpi7/
These are to some extent marginal, as might be expected. The
type, from the Silberling Quarry, has the largest M, recorded, but a
specimen from Loc. 25 approaches this within 0.1 mm. No. 9925,
from Loc. 3, has the widest M, and M; recorded, but these two dimen-
sions are approached within 0.2 and 0.1 mm, respectively, by Loc. 25
specimens. The variation is low for the whole series in any event,
and there is no reason to believe it heterogeneous as to race.
The close approach of this species to T. pliciferus is shown by the
dimensions of M, of the type of the latter, length 7.5, width 6, within
the range of 7. symbolicus but slightly below the mean. The most
readily measurable of the types of T. “minor” = T. pliciferus, Amer.
Mus. no. 3897, has the following dimensions: Length M,, 6.8; width
Mu, 5.6; length Mz, 7.0; width Ma, 6.2.
This is somewhat more representative of the smaller Torrejon
species than is the type of T. pliciferus, which is a large variant.
The lengths are below and the widths at the observed lower limits
for T. symbolicus, and the differences are significant.
Princeton no. 13757, from Loc. 9, one of the rare No. 1 Fort Union
specimens, includes M!~? evidently of Yetraclaenodon and closely
comparable to 7. symbolicus, although the variability of this species,
lack of adequate material of the upper dentition, and some differ-
ences from other specimens, perhaps individual and perhaps of minor
taxonomic value, make the reference uncertain.
TETRACLAENODON cf. PUERCENSIS (Cope, 1881)
A few fragmentary specimens demonstrate the presence of a larger
species of Tetraclaenodon. These include a left upper M? from the
Gidley Quarry (U.S.N.M. no. 9620), associated left dm* and M?
from Loc. 6 (American Museum), associated left M? and part of
250 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
M? from Loc. 82 (American Museum), and specimens figured by
Douglass (1902b, p. 222) from Loc. 5 or 6. These specimens vary
considerably among themselves, and they are not clearly distinguish-
able from variants of 7. puercensis, but they are inadequate for
specific determination and do not definitely establish the presence of
that species in this field.
The original of Douglass’ 1908, pl. 1, fig. 4, is perhaps a right P?
of this same form, but this is uncertain, and the other isolated teeth
referred to Tetraclaenodon by Douglass seem still more dubious.
There are also preserved with U.S.N.M. no. 11913 a right and a
left M! (possibly M?) probably of Tetraclaenodon and, at least in their
worn condition, closely resembling 7. puercensis. They certainly are
not associated with no. 11913, since they are from a much older indi-
vidual, and it is very improbable that they are of the same species,
and not at all clear that they are congeneric. No. 11913 is recorded
as from Loc. 11 or 13. These localities are at about the same level
and are the highest that have yielded identifiable mammals. A note
by Silberling with the specimens seems to leave little doubt that
these specimens were derived from that level except in the highly
improbable case that they have accidentally been substituted for
two other upper molars in the collection. Tetraclaenodon has not
otherwise been reported from beds as late as this, and these teeth
are inadequate to establish its presence although they make it
probable.
Genus GIDLEYINA Simpson ®
Gidleyina Simpson, 1935d, p. 240.
Type.—Gidleyina montanensis (Gidley).
Distribution. Upper Paleocene, Fort Union, Montana.
Diagnosis.—Gidley : ‘Cheek teeth bunolophodont; first and sec-
ond upper molars subquadrate, consisting of four principal cusps,
two intermediates, and a well-developed mesostyle, conules con-
nected by continuous lophs with the summit of the protocone; pre-
molars 3 and 4 with well-developed protocones, but with metacones
rudimentary; thus superficially they each consist of two principal
transversely placed cusps.”
8 The teeth themselves are not marked, as are most specimens in the collection.
§In one draft of his manuscript Dr. Gidley referred the type of this genus to Huprotogonia, in another
to Ectocion, and in a third, presumably the most recent, to Proectocion, new genus. His new generic name
is, however, preoccupied by Proectocion Ameghino, 1904, and therefore it cannot be used. He intended
to change it, for he had made a pencil notation, ‘‘change name, not related to Hctocion, but rather to Pro-
togonodon’”’, but I find no other name in his notes or on his labels and so have been forced to supply one.
It is highly appropriate that the genus should be named for Dr. Gidley. (Gidleya Cossman, 1907, is a fossil
bovid.)
10 Quoted from what is probably the most recent draft of Dr. Gidley’s manuscript, the only one in which
& new genus is proposed.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 251
Simpson: Closely resembling Ectocion, but upper premolars with
much smaller metacones, first and second molars with slightly smaller
mesostyles and hypocones, protoconules of P*-4 and M!? slightly
more united by lophs to protocone.
Discussion.—The molars of this genus can hardly be distinguished
generically from Ectocion, although unlike any known species in
details. The premolars, however, are distinctly less molariform and
at once distinguish Gidleyina from Ectocion. It is well known that
from partial dentitions alone it is often difficult or impossible to
determine even the ordinal affinities of genera in these ancient faunas,
but in this case every indication is that Gidleyina is in fact related to
Ectocion, and perhaps ancestral to it."
If this is correct, it is clear that the Ectocion line was already distinct
from that of Phenacodus in the Middle Paleocene and had already
acquired a mesostyle and slightly more lophiodont pattern, although in
other respects, such as the complication of the premolars, not more
advanced than Tetraclaenodon.”
Among Torrejon genera, Gidleyina most closely resembles Pro-
toselene in many respects but is at once distinguished by the large and
posterointernal protocone on P?, distinct conules on P*, and other lesser
details, suggesting that the relationship is not very close. The dis-
tinctions from Protoselene are resemblances to Ectocion.
In addition to the type, based on an upper jaw, I tentatively
refer two species based on lower jaws to this genus. They are
described below.
GIDLEYINA MONTANENSIS (Gidley)
Figure 72
Gidleyina monianensts (GipLEY) Simpson, 1935d, p. 240.
Type.—Princeton no. 12048, part of left maxilla with P°-M? and a
probably associated right P?.
Horizon and locality—bLoc. 68, about 1,000 feet above Gidley
Quarry, Fort Union, Sweetgrass County, Mont.¥
il This is Dr. Gidley’s opinion in all three drafts of the manuscript on this form, but still later he noted
that affinity is closer with Protogonodon. This seems to me highly improbable and was perhaps noted
rather as a point to check than as a conclusion.
12 In one of his manuscripts Dr. Gidley proposed placing the Tetraclaenodon-Phenacodus and the Gidleyina-
Ectocion phyla in different subfamilies. Even if we grant that the phyla were distinct from Middle Paleo-
cene to lower Eocene, they are so similar that considering them as two subfamilies seems to me dispropor-
tionate to the classification of other groups of mammals.
13 There are now no locality data with the specimen. One of Dr. Gidley’s manuscripts says ‘‘Near sec.
23, R.15E., T.5 N.. . near top of Fort Union No. 2 of Silberling.”’ Localities 4, 52, and 54 are the only
ones in (or near) this section—the Gidley Quarry and a nearby exposure near the same level. As far as I
can determine, no Princeton material came from anywhere near here. Another of Dr. Gidley’s drafts, and
apparently the latest, says ‘“‘From the vicinity of Bear Butte. ... Exact level not known, but probably
from near the middle of the section of this locality.” Mr. Silberling, however, remembers the discovery
of the specimen and positively states that it was found at the locality now numbered 68. T'wo other speci-
mens perhaps of this species are from the cluster of localities in the western part of T. 5 N., R. 15 E., where
most of the Princeton specimens were found, some 1,500 feet above the base of No. 3.
252 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Diagnosis.—Gidley * ‘‘P? to M?=31-+ mm; M!'?=13.1 mm; length
of M'=6.4 mm, greatest width=9.1 mm, width across hypocone and
metacone=8.3 mm, greatest width of M?=9.8 mm, other measure-
ments of this tooth same as those of M'; parastyle and mesostyle
prominent, mesostyle angular and continuous with the ectoloph; P#
with uninterrupted internal cingulum, and with low but well-defined
lophs connecting the summit of the protocone with the protoconule
and base of the metacone respectively.”
FIGURE 72.—Gidleyina montanensis (Gidley), Princeton Univ. no. 12048, left upper jaw: a, External view;
6, crown view. One and one-half times natural size.
Discussion.—The P? probably associated with the type is a simple
2-rooted tooth with one laterally compressed external cusp, somewhat
anterior on the crown, and a small posterointernal expansion of the
base but not true protocone.
My measurements of the type are as follows: P*-M?, 19.6; M'?,
13.8; length P?, 4.5; width P?, 3.1; length P®, 5.9; width P’, 5.8; length
Pt. 5.7;-width.P*,, 7.2; leneth M', 7:0: width M®, 9:0; length: IMe:
6.9; width M?, 9.9.
Two other specimens from the same cluster of localities all at about
the same level are in the Princeton collection. Princeton no. 14195
is an M? similar to that of the type but slightly larger and with the
hypocone more internal. These could be individual variations.
Princeton no. 14190 is an isolated P, 7.2 mm in length and 4.8 mm in
width. Its size is almost exactly that of the corresponding tooth of
2G. silberlingi, but the protoconid and metaconid are closer to each
other and the metaconid is relatively more posterior.
14 J quote Dr. Gidley’s diagnosis from the draft in which he placed the species in a new genus. His other
two diagnoses view it as a species of Tetraclaenodon and of Ectocion, respectively, and are therefore inappro-
priate.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 253
?GIDLEYINA SILBERLINGI (Gidley) '5
Ficure 73
?Gidleyina silberlingit (GiDLEY), Simpson, 1935d, p. 240.
Type—U.S.N.M. no. 6166, partial left lower jaw with P;—Ms.
Collected by A. C. Silberling. (In the same lot are a partial right
lower jaw with M,_3 and another right lower jaw fragment with M,
and the heel of M,;. They probably belong to the same species but
include parts of one or two different individuals and are excluded from
the type material.)
Horizon and locality —tLoc. 27, about 400 feet above the base of
Fort Union No. 3, Wheatland County, Mont.'®
Diagnosis.—Gidley: ‘© ... About the size of or a little smailer
than EL. minor [= Tetraclaenodon pliciferus, G. G. S.J... Jaw rela-
tively long and slender, especially anteriorly ; the teeth proportionately
narrow transversely ... with a decided tendency to selenodonty
... The paraconid in the molars is vestigial or wanting, and P, is
submolariform . . . the heel . . . having the crescentic form of that
of the molars, while the metaconid is large and as high as the
protoconid.”
Discussion.—It is possible that this is the lower dentition of Gid-
leyina montanensis. Since, however, it cannot be demonstrated to
belong even to this genus and since among lower dentitions it is a
distinctive and interesting type that requires some means of reference
until its association with upper teeth can be established, it seems quite
proper to accept Dr. Gidley’s decision to define it as a species, which
can be reduced to synonymy later, if necessary, with no great con-
fusion.
In comparison with other known lower jaws, this is generically dis-
tinct from any previously described. ctocion is similar but has a
simple longitudinal crest on P3, instead of an incipient crescent, while
P, is more complicated and molariform, with a distinct posterointernal
cusp absent in the present specimen. The molars offer no contrast
definitely of generic value, unless it be the somewhat larger and more
definitely closed trigonid basins and less distinct vestigial paraconids
of ?Gidleyina silberlingi. The possibility that Gidleyina is not really
ancestral to Ectocion or, on the other hand, that ?G. silberlingi does
not belong to Gidleyina is enhanced by the fact that whereas the upper
15In a draft of the manuscript on this family, Dr. Gidley describes this as a species of Euprotogonia
(= Tetraclaenodon). Onthespecimen label he has crossed out ‘‘Euprotogonia”’ and written ‘‘Ectocion.’’ It is
thus evident that he recognized the probable relationship of this jaw to the new genus I have named Gid-
leyina, since this was also successively identified by Dr. Gidley as Huprotogonia and as Ectocion before its
generic distinction was recognized. I have not quoted his diagnosis in full, giving only enough to validate
his claim to authorship of the species, since it was written before he had recognized the genus here named
Gidleyina and therefore is not fully apropos. My comparisons following the diagnosis suffice for the expres-
sion of more fully studied opinion as to diagnosis and affinities.
16 Given on labels, etc., as “Sweetgrass County’’, but, as can be seen on the map, this is one of several
localities slightly north of the county line.
254 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
teeth of Gidleyina montanensis are almost ideally prototypal to those
of Ectocion, the lower teeth called ?G. silberlingt seem to be progressing
either more rapidly or in a different direction in the development of
P; and the molar trigonids. This is not certain, however, as these
characters are highly variable and an apparent reversion of this sort
is not inconceivable.
FIGURE 73.—?Gidleyina silberlingi (Gidley), U.S.N.M. no. 6166, left lower jaw: a, Crown view; 5, external
view. One and one-half times natural size.
P, differs markedly from that of Tetraclaenodon in its incipient cres-
cent and basin, but P, is basically similar. The melar paraconid is
much less distinct in ?G@. silberlingi than in most specimens of Tetra-
claenodon, although approached by a few extreme variants of the
latter, and the enamel is much less rugose, the crests less crenulated.
These characters suggest Protoselene, but in the latter even P, is much
less molariform, with the metaconid strong in ?G. silberlingi, barely
incipient at best and the talonid very different.
The following measurements are from the type: Length P3, 6.7;
width P;, 3.9; length Py, 7.2; width Py, 4.7; length My, 7.0; width
My, 5.4; length Mo, 7.3; width Mg, 5.4; length Mg, 7.3; width, Ms, 4.6.
?2?GIDLEYINA SUPERIOR (Simpson)
Figure 74
?Tetraclaenodon superior Simpson, 1935d, p. 239.
Type.—U.S.N.M. no. 11913, part of left lower jaw with talonid of
M,, Me, and M; still in capsule. Collected by A. C. Silberling.”
Horizon and locality.—Loc. 11 or 13, about 3,000 feet above the base
of Fort Union No. 3, Sweetgrass County, Mont.
Diagnosis.—Lower molars with paraconids vestigial, broad trigonid
basins with crenulated anterior margin, crenulations otherwise slight.
17 The two upper molars apparently of Tetraclaenodon, discussed on a previous page, are preserved in the
same lot of material but are not associated with the lower jaw and were definitely excluded from the type
material of this species.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 2p
External cingulum absent, talonids incipiently lophoid. Talonid of
M, markedly narrower than trigonid. Lower molars of about the size
of those of Tetraclaenodon symbolicus but slightly narrower relatively.
Somewhat longer and distinctly wider than those of ?G. silberlingi.
M, length 7.7, trigonid width 6.2, talonid width 5.5.
FIGURE 74.—?Gidleyina superior (Simpson), U.S.N.M. no. ii913, left lower jaw: a, Crown view; 6, internal
view. One and one-half times natural size.
Remarks.—This distinctive but imperfectly known species was at
first referred, with a query, to Tetraclaenodon, but with the comment
that it might belong to Gidleyina. The crucial evidence of the pre-
molars is lacking, but after further study it seems probable that it is
congeneric with ?Gidleyina silberlingi. The relatively slight enamel
crenulation, the structure of the trigonids, and the incipiently lophio-
dont talonids are distinctions from species surely referred to Tetra-
claenodon and points of resemblance to ?G@. silberlingi. Reference to
Gidleyina depends on that of the last-named species, discussed above.
Family PERIPTYCHIDAE Cope, 1882
Subfamily ANISONCHINAE Osborn and Earle, 1895
Anisonchines are among the commonest fossils in the Puerco and
Torrejon, but in the present fauna they are neither abundant nor
varied. One form cannot at present be distinguished from the
Torrejon species Anisonchus sectorius. Only one other form, Cori-
phagus montanus, is recognized. This genus also occurs in the Torre-
jon, but the species is distinct. The recognition that MJizoclaenus
is a synonym of Coriphagus and that these animals are not oxy-
claenids, as generally supposed, but primitive anisonchines clears up a
decided taxonomic anomaly and also casts important light on the
origin and affinities of the Anisonchinae.
The five genera of this subfamily so far distinguished may be recog-
nized by criteria presented in table 59.
BULLETIN 169, UNITED STATES NATIONAL MUSEUM
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FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. DASE
Genus CORIPHAGUS Douglass
Cortphagus Dovatass, 1908, p. 17.
Mizoclaenus MATTHEW and GRANGER, 1921, p. 7.
Type.—Coriphagus montanus Douglass.
Type of Mixoclaenus.—Mizoclaenus encinensis Matthew and
Granger.
Distribution — Middle Paleocene, Fort Union, Montana, and Torre-
jon, New Mexico.
Diagnosis.—P, 1-rooted. P3-, subequal, somewhat swollen but
elongate, with minute anterior basal cusps and small heels basined
posterointernally. Molars relatively small, trigonids larger than talo-
nids and notably higher, paraconids distinct and nearly internal,
trigonids basined with cusps crested, poorly differentiated, and not
conical. M,; much reduced, with hypoconulid distinguishable but
not prominent. P® with very rudimentary protocone, P* with dis-
tinct but small subconical protocone, M!~? transverse, subquadrate,
outer borders angulate and emarginate, distinct hypocones postero-
internal to protocones and on cingula nearly enveloping the latter.
Discussion.—Douglass based this genus and its type species on a
single but unusually complete lower jaw with P,-M3, found by Silber-
ling in the Silberling Quarry. In 1913 and 1916 parties under Dr.
Granger found three * specimens-of a similar form in the Torrejon,
and in 1921 Matthew and Granger described these as Mizoclaenus.
They then noted the resemblance of Mizoclaenus to Coriphagus
but cannot have realized, from Douglass’ somewhat schematic figure,
how close itis. They decided to hold AfMizoclaenus as distinct at least
until discovery of the upper dentition of Coriphagus. Matthew’s
fuller description of Mizoclaenus (Pale. Mem.) was written before
1921 (probably in 1917) and was not corrected. It does not mention
the resemblance to Coriphagus. The upper dentition of Coriphagus
montanus is now partly known, and it has been possible to compare
original specimens of that species and of Mizoclaenus encinensis. The
conclusion is that the two species are unquestionably congeneric and
hence that Mizoclaenus is a synonym of Coriphagus. They compare
very closely in every known part, and the type species of the two
supposed genera differ only in size and doubtfully in slight variations
of proportions.
Douglass (1908) referred Coriphagus to the ?Insectivora, without
family assignment. Matthew and Granger (1921) placed “Mizo-
claenus’”’ in the Oxyclaenidae but noted resemblances to Mioclaeninae
and Anisonchinae.” In his longer work Matthew (Pale. Mem.) has
18 Matthew mentions four, describing only two of them, but I can only find three in the collection.
19 Hay (1930) followed them in placing Mizoclaenus (which he wrongly ascribed to the Tiffany) in the
Oxyclaenidae, but he placed Coriphagus in the Plagiomenidae, a family with which it has practically nothing
in common. Schlosser (1923) placed Mirociaenus (which he wrongly ascribed to the Puerco) in the Oxy-
claenidae and Coriphagus in the Mioclaenidae. These and other casual references are accompanied by no
evidence and require no discussion.
258 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
outlined the evidence in more detail. (He is discussing Mizoclaenus,
which now proves to be Coriphagus.) The only oxyclaenid character
given is “upper molars resembling those of Chriacus’’, but he adds
that they are wider transversely, more triangular, external angles
more prominent,” hypocone less so, and M® much reduced and more
transverse. With these, and other modifications, the resemblance to
Chriacus is really quite attenuated. Matthew notes that the rounded
condyle and other characters of the jaw and the small premolariform
canine are not oxyclaenid but do not approach condylarths or in-
sectivores. I add that they do, almost to identity, approach the
Anisonchinae. Matthew also notes, but rejects as inconclusive, some
resemblance to Didelphodus, leptictids, and Palaeosinopa in the molars,
but adds that the premolars suggest the Mioclaeninae but are more
like the Anisonchinae.
This genus has, in fact, all the diagnostic characters of the Anison-
chinae and nothing that decisively indicates pertinence to any other
group. ‘The upper and lower premolars are of fully anisonchine type
and are especially suggestive of Conacodon cophater.2!_ They differ
in such details, well within the morphological range of the Anison-
chinae generally, as the incipient development of a protocone on P?
and the less transverse P*. This last tooth is intermediate between
the “round premolar cusp” type (Hemithlaeus and Conacodon) and
the “flat premolar cusp” type (Haploconus and Anisonchus), adding
to the evidence already given by Matthew that these are not, as
Osborn and Earle thought, major phyletic divisions of the Anison-
chinae. The lower premolars still more closely resemble those of
Conacodon cophater, the only definite differences being that they are
slightly less inflated and have the anterior basal cuspule a little smaller
(but larger than in Conacodon entoconus). Matthew (Pale. Mem.)
mentions the heavy and peculiar wear on these teeth in Coriphagus
(‘‘Mizxoclaenus’’), truncating them obliquely. This wear occurs in all
Anisonchinae and is almost diagnostic of the group.
The molars are on the whole more primitive or generalized than
those of other anisonchines, which is what induced Matthew to refer
the genus to the Oxyclaenidae. Yet they have the basic anisonchine
characters. The upper molars markedly resemble those of Anison-
chus gillianus and Conacodon cophater, apparently the most primitive
in this respect among other anisonchines. From the former they
differ chiefly in the less rounded outer contour, shorter internal slope,
and development of the hypocone on a cingulum around the protocone.
The first and last of these characters are resemblances to Conacodon
cophater in which, however, the internal slope is also long and the hypo-
cone is more internal, with respect to the protocone, than in Cor-
20 This does not seem to me to be quite certain.
21 Conacodon entoconus differs greatly from the smaller species and might almost be distinguished ‘gin it
generically.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 259
phagus. Mis markedly reduced and very transverse, a resemblance
to Conacodon cophater but here somewhat intensified.
In the lower molars the large swollen trigonids with the tips of the
cusps pinched together, giving an aspect difficult to describe but
characteristic when seen, is diagnostic of Anisonchinae and typically
developed in Coriphagus. The paraconids are retained and are closely
similar to those of Anisonchus gillianus, possibly a trifle more internal,
but hardly more so than in some specimens of that species; in A. sec-
torius they are more definitely median. The molar talonids are rela-
tively smaller and their cusps less conical and distinct, especially on
M;. This is perhaps the most aberrant feature of Coriphagus, con-
sidered as an anisonchine, but the difference from such a form as
Conacodon cophater is really slight.
The characters of the mandible mentioned or shown by Matthew are
almost identical with those of other anisonchines about the same size.
Coriphagus is in many respects the most primitive known anison-
chine, representing, in view of its age, an unprogressive surviving type.
Its closest comparisons are with Conacodon cophater and Anisonchus
gillianus, both Puerco species and older than the known species of
Coriphagus. Coriphagus carries still closer the marked resemblance
already noted between the anisonchine and the hyopsodontid denti-
tions. Were no other anisonchines known, it could very well be classed
as a hyopsodontid representing another incipiently divergent line in
addition to the several already known in that group. But all these
divergent characters are in the direction of the more specialized anison-
chines, and these in turn show marked resemblance to the still more
specialized periptychines. The whole hyopsodontid—periptychid com-
plex seems to bear the definite stamp of divergence from a common
ancestry.
CORIPHAGUS MONTANUS Douglass
Figures 75, 76
Coriphagus montanus Dovatass, 1908, p. 17.
Type.—Carnegie Mus. no. 1669, left lower jaw with P,-M;3. Col-
lected by A. C. Silberling.
Horizon and locality —Type from Silberling Quarry, several referred
specimens from Gidley Quarry, Fort Union, Middle Paleocene horizon,
Crazy Mountain Field, Mont.
Diagnosis.—Smalier than C. encinensis (see measurements). Lower
teeth relatively narrow. M, less reduced relative to other teeth.
Discussion.—The differences in proportions given are not entirely
certain, since they depend on only one specimen of C. encinensis, and
these characters are variable. The size difference is slight and in
itself might not warrant full specific status, but its constant association
with different provenience makes it certainly significant. Every di-
260 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
mension of all three specimens of C. encinensis is larger than the cor-
responding dimension of any of the seven available specimens of
C. montanus. The best single comparison is of the length of M,, which
compares as follows, by Fisher’s formula:
LMi, C. montanus: N 6, M 3.25) 3
TUNE AG eicnicn ee INO SMO San eee
Sy,
iG Z
Aa?
=
FIGURE 75.—Coriphagus montanus Douglass, U.S.N.M. no. 9334, with parts in outline supplied from
U.S.N.M. nos. 9599 and 9685, left lower jaw: a, Crown view; 0, internal view. Four times natural size.
The difference is certainly significant although not great.”
Table 60 gives ranges and means for the National Museum speci-
mens of C. montanus and corresponding dimensions of the paratype of
C. encinensis, Amer. Mus. no. 17074. The material is not sufficiently
abundant for the calculation of other statistical constants.
TaBLE 60.—Numerical daia on lower dentition of Coriphagus montanus and C.
encinensis
C. montanus
Dimension 71RD cea Nera
N R M
TUR yc ee eh Ee ie ees 3 2. 7-2. 8 Ded 3.2
AVE he icy pee ER 3 1. 4-1.7 Linas Zeal:
| Wy ey pees eyo eerie eee ae 2, 2. 3-2.'°5 2. 40 on
AW) Digits Seek ene st Ber eR 2 1. 4-1. 6 1. 50 223
1 Del eee ge Bye yea rey ces 6 3. 1-3. 5 3: 25 Said
NV IN Te Ae oe DES 6 222 DEAS 2.8
1 BY cae RS rap ne Si to 6 2. 5-2. 9 Ete, 3. 4
Walger ec Sak Fae. ey 6 2. 0-2. 4 2.18 2.8
TE IN IGRY Sey) iS AD Rests tones 3 2. 3-2. 8 2. 60 2.9
AAI les eee te pe ti on en 3 1. 7-1. 9 1. 80 22,
ENT yeah ee ss a oe ite 2 8. 2-8. 7 8. 45 9.9
32 The mean of C. encinensis is only 14 percent greater than for C. montanus, and it is to be stressed that this
is not in itself and stated in this way of specific value. The largest specimen of C. montanus is 13 percent
greater than the smallest, and the paratype of C. encinensis is only 6 percent larger than the largest of our
specimens of C. montanus in this dimension. With large series the two species would doubtless intergrade
in size, yet they are certainly distinct.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 261
FIGURE 76.—Coriphagus montanus Douglass, U.S.N.M. no. 9591, left upper jaw, crown view. Four times
natural size.
Ala GZS
a i
WR
beh A
> ig TNC 1 BNO
Rg ale
(cali
AUD
TAS IN We
AN
=
¥
eases
FIGURE 77.—Anisonchus sectortus (Cope), referred specimen from the Lebo, U.S.N.M. no. 9267, right lower
jaw: a, Crown view; 6, external view. Twice natural size.
: S
a —£
SS
fIGURE 78.—Anisonehus sectorius (Cope), referred specimen from the Lebo, U.S.N.M. no. 9263, right upper
jaw: a, External view; 6, crown view. Twice natural size.
262 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
U.S.N.M. no. 9591 is a left upper jaw with P?-M! and about half
of M?, from the Gidley Quarry, which is certainly referable to Cori-
phagus montanus. It is deeply worn but well shows the generic
characters. P? may be slightly less transverse and the external
cingulum of P* weaker than in C. encinensis, and all the teeth are
slightly smaller, but the agreement in structure is very close.
Genus ANISONCHUS Cope, 1881
ANISONCHUS SECTORIUS (Cope, 1881)
Fiaures 77-79
Douglass (1902b, p. 222) described and figured an Anisonchus that
he compared with A. sectorius but mentioned the possibility that it
might be distinct. The National Museum collection includes a series
of excellent specimens of this genus, and their pertinence to Anisonchus
sectorius can be rather positively established, although they may well
pertain to local races as will be pointed out.”
Anisonchus is the only genus represented by good material in this
fauna that seems to be represented here by the same species as that
occurring in the Torrejon. It therefore is a special point of attack
for considering the relationships of these two widely separated Middle
Paleocene deposits, and the material has been subjected to detailed
and lengthy analysis. The results are not entirely conclusive, largely
owing to the small size of the available pure samples, but they never-
theless are of considerable interest, and they also provide data that
must be useful in future work. The full analysis would fill many
pages with numerical and morphological data and calculations, and
so it is not published here in extenso, but only such figures as are most
necessary to illustrate the general conclusions reached.
A study was first made of the Torrejon specimens themselves to
see whether more than one species or race could be distinguished, par-
ticular attention being paid to possible distinction between material
from the two principal fossil levels of the Torrejon. The results of
this analysis were negative: From the data at hand it is not possible
to subdivide the Torrejon material, all of which is referable to Anison-
chus sectorius.4 Despite considerable variation, there is only one
specimen, Amer. Mus. no. 3533, that stands out as strongly aberrant.
It was collected by Baldwin in 1885, and the exact horizon and locality
are not recorded. Even this specimen, however, is so close to typical
A, sectorius that it would be methodologically incorrect to discard it
from the general sample.
2 Labels show that Dr. Gidley referred some of the Fort Union specimens to Anisonchus sectorius and
some to a new species, but he left no diagnosis or discussion. I have carefully endeavored to visualize his
concept of the new species, thinking that it might correspond with one of the inconclusively indicated local
races, but this does not seem to be the case, and I am unable to ascertain the characters relied on by him.
2 It may be noted, however, that Matthew is incorrect in believing one of the cotypes of A. mandibularis
to belong to Anisonchus sectorius. Whatever the position of this very dubious species, it is not a synonym
of A. sectorius and probably does not belong in Anisonchus.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 263
The general statistical data on the simple dimensions of the lower
teeth of all Torrejon specimens of Anisonchus sectorius in the American
Museum are presented in table 61.
TABLE 61.—Numerical data on lower dentition of Anisonchus sectorius
Variate N R M o V
TEP ON UT 2) 8 5. 8-6.8 | 6. 2840.11] 0.30+0,08 4,841.2
1 a 8 2A 1 (pS 22-00 14 0. 40+-0. 10 1D. OFt Sad.
11 CE aes he ee imi ile¢ 5. 3-6. 6 | 5. 86+0. 07 0. 30+0. 05 5. 2+0. 9
Wikis ond fy 17 3.5-4.3 | 3.8840.05 | 0. 22+0. 04 5. 74£1.0
Eee 17 5. 0-5. 8 | 5.4740. 05 0. 22+0. 04 ey
WEN eee 17 3. 5-4. 2 | 3. 87+0. 04 0. 17+0. 03 4.5+0.8
Magee eh 21 4,8-5.6 | 5.3440.04| 0.20+40. 03 3. 8+0.6
WM... ih! 23 3. 7-4.4 | 4.0640.03 | 0.1740. 02 4,140.6
eee 4. 14 5.1-6.1 | 5.58+0.08| 0. 28+40.05 5. 041.0
WM S5i 6222. 14 3.2-4.0 | 3.544005 | 0.2040, 04 5.741. 1
The lower dentition material from the Crazy Mountain Field now
available consists of three specimens from the Gidley Quarry, three
from Loc. 25, four from Loc. 51, and one each from Locs. 50 and 18.
The highest number of comparable specimens from a single horizon
and locality is only three, for P, from the Gidley Quarry.
bh
.o)
ol
pats
‘
J
Number of individuals
4.9 Bi2 fH iSSii! SB Ga
LENGTH Mi
FiGuReE 79.—Histogram of the length of Mi in Anisonchus sectorius (Cope): In solid outline, Torrejon specie
mens (American Museum); in dotted outline, Lebo specimens (National Museum).
By inspection of the specimens and of their dimensions, it is sug-
gested that there is local differentiation. Thus in the series from the
Gidley Quarry, Loc. 25, and Loc. 51, each local sample seems to be
reasonably homogeneous and to differ slightly from that of the other
two localities. In the jaws from the Gidley Quarry the lower molars
are longer, but not noticeably wider, than those from Loc. 25. The
very poor material from Loc. 51 suggests closer agreement with the
Gidley Quarry at least in P, and M,, but two isolated M,’s from there
1192123718
264 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
are closer to those from Loc. 25. This impression of slight heterogene-
ity cannot now be considered dependable or formally recognized.
The differences could hardly be of more than subspecific scope in any
event and perhaps are merely those of separate strains within one
subspecies, and the data are too few to establish them as real.
The best data for material from one locality, dimensions of P, and
M, from the Gidley Quarry, may be compared with the Torrejon
sample by Fisher’s t-test, previously mentioned, with the following
results:
VARIATE N,+ N32 t P
LP, 20 9 99. <0.05>0.02
WP, 20 1.60 <a 0.2). > 0:1
LM; 19 2.83 <0.02>0.01
WM; 19 74 <0;2--051
Thus these two teeth are probably significantly longer, but not
wider, than those of the Torrejon sample as a whole. Since the latter
is heterogeneous in origin and perhaps as to race, it does not neces-
sarily follow that the Gidley Quarry race does not occur in the Torre-
jon, but it probably does not. Comparison of the whole Fort Union
sample, however, shows no significant difference, as the following
figures for the only variates probably significant in the Gidley Quarry
sample show:
VARIATE N,+ Nz t Pe
LP, 25 1.95 <0.1>0.05
LM, 22 1.66 << 0,201
In short, the evidence now is that the Fort Union sample may
include more than one local or temporal genetic group of minor
scope and the same may be true of the Torrejon material. At least
one of these minor groups in the Fort Union is distinct from the
Torrejon sample as a whole and probably from any group included in
the latter. But the definitive separation of these minor groups can-
not be accomplished from the data now available, and there is no
significant difference between the Fort Union Anisonchus as a whole
and that of the Torrejon as a whole. All are referable to a single
species, A. sectorius.
TaBLe 62.—Numerical data on P, of Anisonchus sectorius
Variate N R M o V
5. 3-6. 6 5. 94+0. 05 0. 3140. 04 5SZ2O7T
5-4. 3 3. 920. 04 0. 20+ 0. 03 5. 2+£0. 7
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 265
As an indication of the variation of the whole species as thus known,
data for Py, a rather variable and characteristic tooth best represented
in the combined collections, are here presented (table 62). Individual
measurements of the many specimens studied, and many other data,
are on hand and will be permanently filed.
The uniformity of these results with those based on Torrejon
specimens only is striking. Despite the great increase (one and a
half times) in the size of the sample by the addition of specimens of
widely different provenience, the two means are increased by only
0.08 and 0.04, respectively, the first figure only 0.01 more than the
corresponding standard error for the smaller sample and the second
less than the corresponding standard error. The standard deviations
are altered by amounts considerably less than their standard errors in
the smaller sample and the same is true of one coefficient of variation,
while the other is not changed at all.
The interest of the coefficients of variation for the Torrejon sample
should also be pointed out. One of them, for WP; is unusually high,
but this is largely caused by the single aberrant or abnormal specimen
previously mentioned.”®> If we accept P3 as abnormally variable or as
represented by some extraneous material, the other eight coefficients
of variation range from 3.8 to 5.7 and average 4.8. The accumula-
tion of such figures is of great importance in view of our almost com-
plete lack of any exact knowledge of the variability of fossil species
in samples collected under the usual field conditions.
The preceding discussion is based on lower teeth. The upper
dentitions have also all been examined and compared, but they merely
substantiate the evidence of the lower dentitions, and the samples
are less satisfactory in all respects.
Order PANTODONTA Cope, 1873 (as suborder), new usage
The order Dinocerata (emended from Dinocerea) was proposed for
the uintatheres by Marsh in 1872. In 1873 Cope proposed to reduce
this to subordinal rank and with the new suborder Pantodonta, for
the coryphodonts, placed it in the order Proboscidea. In 1875 the
two suborders were transferred by Cope to a new order Amblypoda.
In 1883 he added to this order the suborder Taligrada, based solely
on Pantolambda, and in 1897, as stated on an earlier page, added the
periptychids to the Taligrada. Marsh in 1884 proposed ‘“‘Ambly-
dactyla” and “Coryphodontia” as strict synonyms of Cope’s names
(which Marsh claimed to be essentially preoccupied) Amblypoda and
35 Omission of this specimen would reduce V from 12.3 to 7.5+2.0.
3% This is within twice the standard error (that is, within the range of probable true values) for all the
‘single coefficients and is within less than the standard error for all but two. If the aberrant individual be
omitted, it is also well within the range of probable true values for P3.
266 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Pantodonta, respectively, but these names have not been generally
accepted.
The classification thus achieved is well summed up by Osborn (1898):
Order AMBLYPODA:
Suborder Taligrada:
Periptychidae.
Pantolambdidae.
Suborder Pantodonta:
Coryphodontidae.
Suborder Dinocerata:
Bathyopsidae.
Uintatheriidae.
This arrangement is now classic and with slight modifications has
since come into all but universal use. Nevertheless, in the light of
later discovery and research, it has little to recommend it.
The probable affinities of the periptychids with the condylarths,
rather than with the pantolambdids, have been discussed on a pre-
vious page. On the other hand, all recent work (see especially Simp-
son, 1929d, and Patterson, 1934) tends to emphasize the essential
unity of Pantolambda and Coryphodon and their respective allies.
The known pantolambdids are not ancestral to the known corypho-
donts, and family separation is warranted, but they are so simular in
structure aside from primitive or progressive features generally cor-
related with greater or lesser age that there seems no reason to place
them in separate suborders, and the distinction between Taligrada
and Pantodonta is unwarranted.
The uintatheres, on the contrary (Simpson, 1929d and elsewhere),
seem to be a group independent of the pantolambdids and cory-
phodonts from a very remote time and linked to them only through a
prot- or perhaps even pre-ungulate, non-“amblypod” ancestry. The
classic arrangement was undoubtedly influenced by the belief that
taligrades, pantodonts, and dinoceratans represented offshoots of a
single stock appearing successively in time with correspondingly
progressive specializations. Now it is clear that this simple picture
does not correspond to the facts. Among the supposed ‘‘taligrade’’
periptychids the more advanced members are the only ones that
show any considerable resemblance to the pantolambdids in foot
structure, but they cannot possibly be ancestral to the latter not only
because they are contemporaneous but also because aside from the
feet (and in part including them) their structure is very different.
The idea of successive offshoots does apply to the pantolambdids and
coryphodonts, but it decidedly breaks down again with the cory-
phodonts and uintatheres because these groups are not successive but
contemporary phyla, and it is the latest and most advanced members
of each that show some resemblance, which hence is only convergent,
and the earlier members are even more decisively dissimilar.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 267
The classification seems, in fact, to have been based on grades of foot
specialization, over the prototypal ungulate foot, rather than on
characters peculiar to natural phyla. It thus united periptychids
and pantolambdids because they had advanced relatively little in
limb structure, even though their phyletic relations must have been
distant. It separated (subordinally) pantolambdids and cory-
phodonts because the former were less and the latter more advanced in
limb specilization, despite the clear evidence that these groups are
closely related phyletically. And finally it united coryphodonts and
uintatheres because both have specialized limb structures, but over-
looked their marked phyletic separation.
The revision of nomenclature for the accurate representation of
these newer points of view is difficult. The following diagram shows
the relationships of the classic names to the groupings now considered
natural:
@ondylarthra®: 2-222. - eee ; = |
FAM DLy DOCas2 2 ene eae eee fi rs
Taligrads. 2222 2* 30 e As originally proposed.
iPantodonta s--eoesee= = ;
Dinoceratas-.--sseceeoe—e
Condyilarthra=- == = 5-24. =--
AM Dy pOGRss-sesee seen =e F = As subsequently modified by
alioradas 225 [sets ete | 4 t Cope and accepted by most
Pantodonta==---+-s.e.—e 1 other authors.
Dinoceratas=----2— eee
Condylarthral= 225. = i >
Pantodontass ate seoo eae sen
Dinocerata-. is. 502 _ Arve a, As here modified.
8 3
as EF
aaa g Bras ae
os oO Lo} = ago
ea ie al Mec =a Ue
° | g g ES
go 5 a a3 | am
ios is 3 a Sw
3 I | e A
in| aigrt | neolne: olds
Since both periptychines (‘‘Catathlaeus’’) and anisonchines (Anison-
chus) were explicitly cited among the genera belonging to the Con-
dylarthra when that group was first proposed, since most definitions
of Condylarthra need little or no alteration to include the periptychids,
and since no other ordinal or subordinal name has been based primarily
on the periptychids, the removal of the Periptychidae to the Condy-
larthra raises no nomenclatural problem.
268 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
The name Dinocerata was originally based on the uintatheres alone
and has always been taken as referring to them and including only
them,” so there can be no question as to the propriety of continuing
this name in this usage.
What remains is to settle on a name for the Pantolambdidae and
Coryphodontidae. Some students (including me, 1931) have used
“‘Amblypoda” essentially in this sense, usually including the Perip-
tychidae. There is good precedent for such a restriction of a name to
one of several groups formerly included in it, and it is generally more
advisable than coining a new name. In the present case, however, it
should be avoided if possible. “‘Amblypoda”’ was based about equally
on the coryphodonts and the uintatheres. To exclude the uintatheres
from it is not quite the removal of the type group but certainly is a
radical change in usage and one not well justified.
The name “Taligrada” might be expanded to this usage, but this
also is objectionable. As originally defined it was carefully drawn so
as to exclude and contrast with the best-known members of the group
for which a name is now sought, that is, the coryphodonts. Further-
more, in the past 40 years it has almost invariably been taken to
include or even to be typified by the periptychids.
“Pantodonta” has none of these objections. It was proposed and
has always been used for typical members of the group now in question.
No animals foreign to this group have ever been called pantodonts.
Its original definition, although brief, offers a good contrast with both
Condylarthra and Dinocerata, even as those groups are now under-
stood, and would include the pantolambdids (not known when the
name was proposed), so that we are using the name exactly in the
sense of the original author, in fact more so than he did later. The
fact that a group that he later excluded from the Pantodonta is now
included seems to be of no particular importance, especially as his
original conception is not thereby changed. It is entirely proper in
taxonomy to extend a name formerly applied to one group to include
another later found to be closely related and is open to much less
question than would be the exclusion from a named group of a sub-
division on which it was originally largely based (as in excluding
uintatheres from the Amblypoda). The name “Amblypoda” I
would discard altogether, as not pertaining to any group acceptable
as natural or convenient in modern taxonomy.
The present conception of the group Pantodonta may be summarized
as follows:
27 Marsh did suggest synonymy with Cope’s broader ‘‘Amblypoda’’, but in fact nothing but the uinta-
theres was meant to be included in the original description and Marsh later (1884) accepted this restriction,
for he proposed ‘‘Amblydactyla” to replace ‘‘Amblypoda”’ and to include both coryphodonts and uin-
tatheres, with only the latter listed as ‘‘Dinocerata.”
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 269
Order Pantoponta: A group of middle-sized to large, very archaic ungulates (or
“subungulates’”’). The dentition is little or not reduced in number, and
remains practically brachyodont, but exhibits a high degree of lophiodonty
even in the earliest members. The primitive pattern is strongly selenodont
but this is secondarily masked to some extent in later forms. The canines
are apparently always large, and may develop into great tusks. Skull and
jaws are generally massive with very powerful muscle attachments. The
brain remains very small and primitive. The limbs are massive and strong,
ambulatory to graviportal, and retain many primitive features such as
separate radius and ulna, tibia and fibula, and five toes on each foot.
Carpus and tarsus retain and strongly accentuate the alternating arrange-
ment.
Family Pantolambdidae: Relatively less advanced forms, with the teeth
fully selenodont, the skull roof little or not flattened, the tail long
and heavy, and other primitive characters.
Subfamily Pantolambdinae: Lighter, more ambulatory types of smaller
size and with astragalus still retaining some condylarth characters.
Middle Paleocene. North America.
Subfamily Barylambdinae: Heavy graviportal types of larger size, with
fully specialized pantodont type of astragalus. Upper Paleocene.
North America.
Family Coryphodontidae: Highly specialized forms, large in size, all with
graviportal limbs, teeth with primitive crescents considerably modified,
skull roof broad and flat, tail reduced. Upper Paleocene—lower Eocene
in North America. Lower Eocene in Europe. Upper Eocene to Middle
Oligocene in Mongolia.
Family Pantolambdodontidae: A somewhat dubious group known from
lower jaws only, which suggest relationship with Pantolambda but have
numerous differences in details. Upper Eocene. Mongolia.
The present fauna contains few remains of pantodonts, but Panto-
lambda is represented by various fragmentary specimens, some of
which indicate a species first defined, and at present known only, from
this fauna.”
Family PANTOLAMBDIDAE Cope, 1853
Genus PANTOLAMBDA Cope, 1883
Douglass (1902b, p. 224) described and figured an upper premolar
perhaps of this genus. It is about the size of P? of P. bathmodon, but
differs somewhat in form, the main cusp being more central and the
external margin less sharply notched. The National Museum ma-
terials does not serve to define this form. The second Pantolambda
mentioned by Douglass (1908, p. 24) probably belongs to the species
defined below.
28 The present conception of the Pantodonta, especially as regards its essential unity as here defined,
Owes much to Patterson’s discovery of complete skeletons of Barylambda and to his fine studies of them (Pat-
terson, 1933, 1934, 1935, 1937). Although not from the Crazy Mountain Field, the type species and specimen
of Titanoides was found in the Fort Union and named and described by Gidley (1917), and it was originally
proposed to include a discussion of it in this work, but Patterson’s studies make this quite unnecessary.
270 BULLETIN 169, UNITED STATES NATIONAL MUSEUM
PANTOLAMBDA INTERMEDIUS Simpson
Figure 80
Pantolambda intermedius Simpson, 1935d, p. 244.
Type.—U.S.N.M. No. 8384. Left lower jaw with M,_, and alveoli
of C-P,, associated with symphysis fragment with right I,_. and
alveoli of left I,_;. Collected by Dr. J. W. Gidley.
Horizon and locality—Gidley Quarry, Fort Union, Middle Paleocene
horizon, Crazy Mountain Field, Mont.
<F NSS 8) Vins
AO
IeZ7ien Kd ‘itn AG
ANG welt NE
WSAs Nev a
NY
Mi iV
ag
ee
= = 5)
\==
7
UR
ral ND)
FiaurE 80.—Pantolambda intermedius Simpson, U.S.N.M. no. 8384, right lower jaw: a, Crown view; },
external view. Natural size.
Dragnosis.—Intermediate in size between P. bathmodon and P.
cavirictus. P, with one large root, close to canine, followed by short
diastema. P,_, 2-rooted. Lower molars closely resembling those of
P. cavirictus but entoconid more distinct.
Discussion.—The type has M,_, somewhat corroded on the inner
side. An isolated lower premolar, probably P., no. 9598, from the
same quarry as the type, is probably of this species. It is 2-rooted
(as was P, of the type) and is as long as P; of P. cavirictus but is con-
siderably narrower and simpler. In P. cavirictus the posterointernal
crest from the main apex bifurcates and a sharp branch runs from it
anterointernally, whereas in this tooth the posterointernal descending
crest is less prominent throughout and has no bifurcation or antero-
internal branch. The talonid is a narrow, simple heel.
On the whole this species seems to resemble P. cavirictus but is
both smaller and more primitive structurally. Length M,, 13.2;
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. Pa (al
width M,, 11.2; length Mb», 14.8; width Mz, 12.1; length P, (referred)
11.8; width P. (referred), 6.8. (The widths may have been a little
greater before the teeth were corroded.)
PANTOLAMBDA or allied genera, species undetermined
U.S.N.M. no. 6155 is an isolated M? from “‘% mile N. of Fish Creek
Creek 200 ft. E. of Melville and Harlowton Road’’, in Fort Union
No. 3. This almost certainly means Loc. 28; it is about a half mile
from Fish Creek, but no other mammal locality more nearly corre-
sponds with the indication. This horizon is 400 feet above the base
of No. 3 and about 550 feet above the Gidley Quarry. This tooth
resembles the smaller Torrejon specimens referred to P. cavirictus
but has the cingula, external and internal, better developed.
No. 9858, from Loc. 18, well up in Fort Union No. 3, is a frag-
ment of an upper molar probably of the same species as no. 6155.
No. 9694, from Loc. 54, the same level as the Gidley Quarry, is a
symphysis and isolated M,., which also approach small P. cavirictus in
size and is perhaps of this same species, although possibly still smaller.
It is nearer P. cavirictus than P. intermedius in size.
No. 10048, from the Gidley Quarry, closely resembles a lower
posterior premolar of Pantolambda bathmodon in form but is smaller,
7.3 mm long and 5.9 wide.
All these specimens are inadequate for determination, but they
show that pantolambdids were not uncommon in this general area
and that they were varied, despite the fact that conditions did not
lead to the good preservation of their remains.
There are also isolated bones, without associated teeth, from the
horizon of the Gidley Quarry and in one unimportant case, the base of
No. 3, which probably belong to Pantolambda. All are as large as the
corresponding parts of Torrejon P. cavirictus and differ only in insig-
nificant details. Since the probabilities suggest that some of these
belong to P. intermedius, it may be that the latter was a small-headed
form, with body equal to P. cavirictus in size but jaws and teeth con-
siderably smaller. In the absence of associated material, however,
this is obviously hypothetical.
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Amer. Mus. Nov., no. 333, 19 pp., 6 figs.
Stmpson, GEorGE GaAyYLorpD, and Ror, ANNE.
. The use of numerical data in zoology. (In press.)
SrncLairn, WILLIAM JOHN, and GRANGER, WALTER.
1911. Eocene and Oligocene of the Wind River and Bighorn basins. Bull.
Amer. Mus. Nat. Hist., vol. 30, pp. 83-117, 4 figs., 6 pls.
1912. Notes on the Tertiary deposits of the Bighorn basin. Bull. Amer.
Mus. Nat. Hist., vol. 31, pp. 57-67, 2 figs., 2 pls.
Sranton, TimorHy WILLIAM.
1909. The age and stratigraphic relations of the ‘‘Ceratops beds’’ of Wyoming
and Montana. Proc. Washington Acad. Sci., vol. 11, pp. 239-293.
1914. Boundary between Cretaceous and Tertiary in North America as
indicated by stratigraphy and invertebrate faunas. Bull. Geol.
Soc. Amer., vol. 25, pp. 341-354.
FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. ZL
Stanton, TimotHy WILiiaM, and Hatcusr, Jonn BELL.
1905. Geology and paleontology of the Judith River beds, with a chapter on
the fossil plants by F. H. Knowlton. U.S. Geol. Surv. Bull. 257,
174 pp., 19 pls.
STEHLIN, H. G.
1916. Die Saugetiere des schweizerischen Eccaens, pt. 2. Abh. schweiz. pal.
Ges., vol. 41, pp. 1,299-1,552, 82 figs., 2 pls.
Srone, RatpH WALTER.
1909. Coal near Crazy Mountains, Mont. U.S. Geol. Surv. Bull. 341, pp.
78-91, 1 pl.
STONE, Ratpu Wa.tTer, and CaLvert, WILLIAM R.
1910. Stratigraphic relations of the Livingstone formation of Montana.
Econ. Geol., vol. 5, pp. 551-557, 652-669, 741-764, 2 pls.
TEILHARD DE CHARDIN, PIERRE.
1916, 1921. Les mammiféres de I’ Kocéne inférieur frangais et leurs gisements.
Ann. Paléont., vol 10, pp. 171-176, 1916; vol. 11, pp. 1-108, 1921;
42 figs., 8 pls. (Also with serial pagination 1-116.)
Tuom, WituraM Taytor, JR., and Dopsin, CarroLtt Epwarp.
1924. Stratigraphy of Cretaceous—Eocene transition beds in eastern Montana
and the Dakotas. Bull. Geol. Soc. Amer., vol. 35, pp. 481-505, 3
figs., 3 pls.
WEED, WALTER HARVEY.
1893. The Laramie and the overlying Livingston formation in Montana,
with report on flora by F. H. Knowlton. U.S. Geol. Surv. Bull.
105, 68 pp., 6 pls.
1894. Livingston, Mont., folio. U.S. Geol. Surv. Geol. Atlas no. 1, [5] pp.,
4 maps.
1896. The Fort Union formation. Amer. Geol., vol. 18, pp. 201-211.
1899. Little Belt Mountains, Mont., folio. U.S. Geol. Surv. Geol. Atlas no.
56, 11 pp., 4 maps.
WEGEMANN, CARROLL HaRvVeEy.
1917. Wasatch fossils in so-called Fort Union beds of the Powder River
basin, Wyo., and their bearing on the stratigraphy of the region.
U.S. Geol. Surv. Prof. Paper 108d, pp. 57-60, 2 pls.
Wootsry, Lester Hoop; RicHarps, RALPH WEBSTER; and LupTon, CHARLES
THOMAS.
1917. The Bull Mountain coal field, Mussellshell and Yellowstone Counties,
Mont. U.S. Geol. Surv. Bull. 647, 218 pp., 36 pls.
WorrMan, Jacosp Lawson.
1901-1904. Studies of Eocene Mammalia in the Marsh collection, Peabody
Museum. Amer. Journ Sci., vol. 11, pp. 333-348, 6 figs., 1 pl.;
pp. 437-450, 11 figs., 1 pl.; vol. 12, pp. 143-154, 13 figs.; pp. 193-
206, 13 figs.; pp. 281-296, 1 fig., 1 pl.; pp. 377-3882, 4 figs.; pp.
421—432, 12 figs., 1 pl.; vol. 13, pp. 39-46, 4 figs.; pp 115-128,
6 figs ; pp. 197-206, 12 figs.; pp. 433-448, 13 figs.; vol. 14, pp.
17-23, 2 figs.; vol. 15, pp. 163-176, 5 figs.; pp. 399-414, 419-436;
vol. 16, pp. 345-368, 15 figs.; vol. 17, pp. 23-83, 4 figs.; pp. 133-
140, 11 figs.; pp. 203-214, 14 figs. (Also a separate edition in 2
parts, paged serially 1-250, to which reference is made.)
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169 PLATE 2
BULLETIN
U.S. NATIONAL MUSEUM
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U.S. NATIONAL MUSEUM BULEEERIN 169. PEATIE:S
FORT UNION GROUP, CRAZY MOUNTAIN FIELD, MONT,
FOR EXPLANATION OF PLATE SEE OPPOSITE PAGE,
PLATE 3
1, Air view, looking approximately south, with Sec. 33, T. 6 N., R. 16 E., near the
middle of the picture (prominent but small isolated timber butte in this
section). The meandering watercourse is Widdecombe Creek and _ is
developed on the nonresistant Upper Lebo (Fort Union No. 2), as are the
other low sodded areas through the central part of the picture. The main
timbered ridge across the photograph is the northwest side of Bear Butte.
The broken area between the small outlying butte and the patch of timber
(on Bear Butte) farthest to the left, just beyond the road, is Loe. 5, one of
Douglass’ two localities where mammals were first found in the Fort
Union. Part of Lion Butte forms the skyline in the center and right parts
of the picture.
2, Air view of the east side of the north end of Bear Butte, looking approximately
south in See. 34, T.6 N., R. 16 E. The rimrock of Bear Butte, along the
upper edge of the picture, is the basal Melville (No. 3) sandstone, and the
rest of this area is all on the Upper Lebo (No. 2). The shale exposure in
the coulee above the road in the upper left of the picture is Loe. 6, one of
Douglass’ discovery sites.
PLATE 4
1, Air view of the Gidley Quarry and vicinity, looking slightly north of east, the
foreground in See. 28, T. 5 N., R. 15 E. The slope in the foreground, on
which the quarry is visible, is on the Upper Lebo (No. 2), as is also the
broad valley of the Widdecombe Creek in the upper left. The higher
level in the upper and right parts of the picture, and along the horizon, is
supported by the basal Melville (Fort Union No. 3) sandstone. It is
typically marked by evergreen timber, but in the foreground this timber
extends sparsely well down onto the Lebo, but only on talus derived from
the Melville. Bear Butte is dimly visible along the left part of the horizon,
and a small corner of Lion Butte is seen in the upper right corner. Between
these, small hills upheld by isolated patches of the Melville may be seen.
2, Air view of the Gidley Quarry, a closer view, looking more to the north, of part
of the foreground of fig. 1. The picture was taken in 1935 and shows an
advanced stage in the American Museum quarrying operations. The
approximate area covered by the U. 8S. National Museum work (and since
filled in) is indicated by dotted lines. The larger section (A of Silberling’s
notes) is on the far (north) side of the small coulee, and the smaller (B)
on the near side. The original discovery was made in the coulee near the
spot marked by the cross.
U.S. NATIONAL MUSEUM BULLETIN 169 PLATE 4
FORT UNION GROUP, CRAZY MOUNTAIN FIELD, MONT.
FOR EXPLANATION OF PLATE SEE OPPOSITE PAGE.
U.S. NATIONAL MUSEUM BULLETIN 169" (PEATESS
FORT UNION GROUP, CRAZY MOUNTAIN FIELD, MONT.
FOR EXPLANATION OF PLATE SEE OPPOSITE PAGE.
PLATE 5
1, Air view, looking approximately west-northwest, the foreground in Sec. 4, T.
5 N., R.16 E. The small drainage basin in the foreground is on the Upper
Lebo (Fort Union No. 2). The Silberling Quarry is in the upper part of
the main right (northwest) branch of the coulee. The sparse timber marks
the basal Melville (No. 3) sandstone and the top of Bear Butte, which here,
near the middle of its length, is at its narrowest point. Beyond this is the
valley of Widdecombe Creek, hidden by Bear Butte, and beyond this, dim
in the photograph, rise low hills, without timber, developed on the Lower
Lebo (No. 1) along the axis of the Widdecombe Creek anticline.
2, Site of the Silberling Quarry, looking approximately north in Sec. 4, T. 5 N.,
R. 16 E. The two figures near the middle of the picture stand near the
ends of the main section of the quarry. The slope is on the uppermost
part of the Lebo (upper No. 2), but the basal Melville (No. 3) lies immedi-
ately above, and numerous talus blocks from it are seen. The quarry is
not discernible as such, since the picture was taken in 1932, 24 vears after
intensive work there.
PLATE 6
1, Typical exposure of the Lower Melville sandstone, looking approximately north
in Sec. 23, T.5 N., R. 15 E. The valley in the upper right corner is on the
Upper Lebo (No. 2), with low barren hills of the Lower Lebo (No. 1)
beyond it.
2, Shell imestone in the Melville at Loc. 40, Sec. 29, T.5 N., R. 15 E. Such beds
characterize the middle part of the Melville, although the formation is
predominantly of sandstone and shale. The invertebrate beds are gen-
erally not so thick or so well exposed as they are at this locality. The
apparent nodules are gastropod shells.
169 PLATE 6
BULLETIN
U.S. NATIONAL MUSEUM
‘A9Vd ALISOddO AAS ALV1d AO NOILYNW1dxa HOA
“LNOW ‘O13I14 NIVLNNOW AZVYHO ‘NOILVWHOS ATIIATAW
U.S. NATIONAL MUSEUM BULLETIN i169 PLATE 7
3
FORT UNION PRIMATES.
1, Palaechthon alticuspis Gidley, part of right lower jaw with P2-M», type (U.S.N.M. no. 9532), external
view, Gidley Quarry; 2, Paromomys maturus Gidley, part of right lower jaw with P:-Ms, paratype
(U.S.N.M. no. 9545), external view, Gidley Quarry; 2a, same, crown view; 3, P. maturus, part of
right lower jaw with Py-M;, type (U.S.N.M. no. 9473), external view, Gidley Quarry; 3a, same,
crown view. (All figures about four times natural size; after Gidley.)
U."S. NATIONAL MUSEUM BULLETIN 169 PLATE 8
3
FORT UNION PRIMATES.
1, Pronothodectes matthewi Gidley, part of left lower jaw with Ps-Ms, paratype (U.S.N.M. no. 9531), external
view, Gidley Quarry; 2, Paromomys maturus Gidley, part of right lower jaw with P:-Ms, paratype
(U.S.N.M. no. 9475), external view, Gidley Quarry; 2a, same, crown view; 3, P. maturus, part of
left lower jaw with P:-M3, paratype (U.S.N.M. no. 9337), external view, Gidley Quarry. (All
figures about four times natural size; after Gidley.)
U.S. NATIONAL MUSEUM BULLETIN 169 PLATE 9
FORT UNION PRIMATES.
FOR EXPLANATION OF PLATE SEE OPPOSITE PAGE.
PLATE 9
Plesiadapis gidleyi (Matthew), left upper molar, U.S.N.M. no. 10765, crown
view. From the Tiffany beds near Ignacio, Colo.; for comparison with
Pronothodectes.
Pronothodectes matthewi Gidley, right P*-M2?, type (U.S.N.M. no. 9547), crown
view. Gidley Quarry.
Plesiadapis gidleyt (Matthew), right Pt, U.S.N.M. no. 10659, crown view.
From the Tiffany beds near Ignacio, Colo.; for comparison with Prono-
thodectes.
Plesiadapis rex (Gidley), left lower molar, type (U.S.N.M. no. 9828), crown
view. Gidley Quarry.
Palaechthon alticuspis Gidley, right M!—, paratype (U.S.N.M. no. 9550),
crown view. Gidley Quarry.
Palaechthon alitcuspis Gidley, right M'!—, paratype (U.S.N.M. no. 9551),
crown view. Gidley Quarry.
Paromomys depressidens Gidley, right P*-M*, type (U.S.N.M. no. 9546),
crown view. Gidley Quarry.
Undetermined, probably primate upper incisor, U.S.N.M. no. 10090, lingual
view. Gidley Quarry.
Undetermined, probably primate upper incisor, U.S.N.M. no. 10010, lingual
view. Gidley Quarry.
Undetermined, probably primate upper incisor, U.S.N.M. no. 9928, lingual
view. Gidley Quarry.
Probably Pronothodectes matthewt Gidley, upper incisor, U.S.N.M. no. 10005,
lingual view. Gidley Quarry.
Probably Pronoihodectes matthewt Gidley, upper incisor, U.S.N.M. no. 10044,
lingual view. Gidley Quarry.
Undetermined lower incisor, possibly Plestadapis rex, U.S.N.M. no. 9827,
lateral view. Probably Loc. 138.
Undetermined, possibly multituberculate lower incisor, U.S.N.M. no. 9552,
lateral view. Gidley Quarry.
Undetermined, pair of upper incisors, U.S.N.M. no. 9917, lingual view.
Gidley Quarry.
Plesiadapis gidleyt (Matthew), poorly preserved upper incisor, U.S.N.M.
no. 10639, lingual view. From Tiffany beds, 514 miles east of Bayfield,
Colo.
(All figures about four times natural size; after Gidley.)
U.S. NATIONAL MUSEUM BULLETIN 169° PLATE, 10
FORT UNION PRIMATES.
1, Palenochtha minor (Gidley), part of right lower jaw with Ps-Ms3, type (U.S.N.M. no. 9639), external
view; la, same, crown view; 2, Llphidotarsius florencae Gidley, part of left lower jaw with P;-Ms;,
type (U.S.N.M. no. 9411), external view; 2a, same, crown view; 3, Pronothodectes matthewi Gidley,
part of left lower jaw with base of incisor, canine (?), P2 and Py-M3, U.S.N.M. no. 9332, external
view; 3a, same, crown view. (All figures about four times natural size; after Gidley. All from
Gidley Quarry.)
INDEX
(Principal references are given in boldface)
Abel, O., 86, 115, 141, 165.
absarokae, Didelphodus, 110.
Absarokee, Mont., 27.
Absarokius, 144, 145, 168.
aceroides, Platanus, 19.
Acmeodon, 106-111.
acmeodontoides, Emperodon, 109.
acolytus, Ellipsodon, 53, 225, 227, 233,
234, 239.
Mioclaenus, 225.
acutus, Viverravus, 208, 209.
Adam, Lake, Mont., 13, 23, 37.
Adapinae, 148.
Adapis, 148.
admirabilis, Ptilodus, 84, 85.
affinis, Sapindus, 19.
agapetillus, Anisonchus, 225.
Oxyacodon, 225, 227.
Alder, 58.
Allognathosuchus, 59.
Almagre formation, 196.
alticuspis, Palaechthon, 33, 47, 62, 156
seq., 159.
Amblydactyla, 265, 268.
Amblypoda, 217, 218, 265-268.
amblyrhyncha, Populus, 57.
American Fork, Mont., 13.
American Fork formation, 14.
americanus, Eucosmodon, 83, 104.
americanus primus, Eucosmodon, 83,
103, 104.
Ampelopsis, 57, 58.
Anacodon, 180, 195.
Anaptomorphidae, 33, 60, 61, 142 seq.
Anaptomorphus, 144.
anceps, Plesiadapis, 35, 47, 50, 51, 156,
168, 169.
angustidens, Mimotricentes, 34, 36, 37,
47-49, 52, 194, 197, 205 seq.
Anisonchinae, 124, 217, 223, 224, 255
seq.
Anisonchus, 2, 50, 62, 216, 256, 258,
262 seq., 267.
agapetillus, 225.
gillianus, 258, 259.
mandibularis, 262.
sectorius, 34, 37-41, 48, 50, 51, 53,
54, 255, 259, 261, 262 seq.
Apatemyidae, 147.
Apatemys, 144.
Apheliscidae, 124.
Apheliscus, 124.
Aphronorus, 106, 121, 124 seq.
eee 33, 38, 47, 58, 62, 124
, 140.
peiediatus, Oxyacodon, 225-227.
119212—37—_19
aquilonius, Ellipsodon, 34, 37, 39, 47, 62,
66, 227, 233, 234 seq., 238, 240.
arachioides, Leguminosites, 57.
Aralia notata, 57.
Arbor-vitae, 58.
Arctocyon, 171, 180.
primaevus, 7.
ee ueeygnidee 34, 60, 61, 170, 171 seq.,.
207.
Arctocyonides, 172.
Arctocyoninae, 170-172, 173 seq.
Arctoryctes, 139, 140.
Artiodactyls, 220, 225, 229-231.
asaphes, Unuchinia, 35, 47, 68.
Aspideretes nassau, 59.
australis, Thryptacodon, 42, 48, 68.
Baldwin, D., 7, 233, 262.
Barylambda, 11, 222, 269.
Barylambdinae, 269.
bathmodon, Pantolambda, 269-271
Bathyopsidae, 266, 267.
Bats, 136.
Bear Butte, Mont., 13, 16, 22, 28, 24, 28,
31, 38.
Bear Creek, Mont., 11, 170.
Bear formation, 15, 17 seq., 21, 26-28,
55; 57.
Bearpaw formation, 15, 16.
Bears, 180, 182.
Beech, 58.
belgicus, “Omomys’’, 144.
Belt uplift, Mont., 14.
Bessoecetor, 51, 52, 106, 121, 122 seq.
diluculi, 33, 47, 122 seq.
thomsoni, 35, 47, 50, 122, 123.
Big Elk sandstone, 15.
Bighorn Basin, Wyo., 55, 83.
Bighorn Mountains, Wyo., 116 Ue
Big Snowy Uplift, Mont., 14,
Bigtimber, Mont., 12.
Bigtimber Creek, "Mont., 13.
Billings County, N. Dak., 11.
Birch, 58.
Bittersweet, 58.
Blainville, H. M. de, 7.
Bolodon, 70.
Bridger formation, 143.
Broom, R., 71, 72, 86, 89-92.
Brown, Be He 14,
Buford, N. Dak., Tey dle
Bull Mountain Field, Mont., 26, 58.
Burke, J. J., 6.
Cabrera, A., 64, 246.
Cabrera’s Law, 64 seq.
Caenolestes, 115.
Caenolestidae, 136.
Caenopithecus, 161.
279
280
Calamodon, 169.
Calvert, W. R., 9, 16, 19, 21, 22, 24, 26,
27, 57.
Campbell, M. R., 9, 57.
Campeloma, 17, 58.
limnaeiforme, 17.
nebrascense whitei, 17.
canadensis, Physa, 17.
Carnivora, 34, 60, 61, 170 seq.
Carpites, species undetermined, 57.
Carpodaptes, 50, 51, 58, 161, 162, 164.
hazelae, 35, 47.
Carpolestes, 53, 144, 147, 161, 162, 164.
dubius, 162.
Carpolestidae, 33, 60, 61, 161 seq.
Catathlaeus, 216, 267.
cavirictus, Pantolambda, 41, 270, 271.
Cayuse Butte, Mont., 8, 9, 18, 25, 29,
35, 41.
Champsosaurs, 17, 36, 59.
Cheiromyoides, 165.
Chestnut, 58.
Chiroptera, 119, 135, 136.
Chirox, 70.
Choeroclaenus, 226, 228, 232 seq.
turgidunculus, 226, 227.
Chriacidae, 171, 172.
Chriacinae, 172, 173.
Chriacus, 52, 171-173, 192-194,
seq., 198, 199, 201, 203, 258.
pelvidens, 197.
pugnax, 36, 47, 48, 194, 196, 197.
pusillus, 194, 197-199.
species undetermined, 35, 47.
Chrysochlorid, 140.
Cimolomys, 98.
gracilis, 85.
Claenodon, 2, 42, 50, 52-54, 62, 67, 173,
174 seq., 190, 191, 195, 197, 224.
corrugatus, 174-181.
ferox, 39-42, 47, 49-51, 54, 55,
174-179, 180 seq., 182-185, 189.
latidens, 34, 47, 176, 187 seq., 190.
montanensis, 34, 38, 47, 175, 176,
181 seq., 187-189.
procyonoides, 176.
protogonioides, 175-177, 181, 186.
silberlingi, 34, 42, 47, 176, 185 seq.,
196
188, 189.
species undetermined, 34, 47, 189
seq.
species unnamed, 176, 178.
vecordensis, 36, 47, 48, 176, 189.
Claenodonts, 10.
Claggett formation, 15.
Clark Fork Basin, Wyo., 81, 83.
Clark Fork formation, 11, 16, 20, 21, 81,
83.
Cloverley formation, 14.
cochranensis, Ectypodus, 77, 82, 83,
100, 101.
Colorado group, 14, 15.
comma, Conoryctes, 34, 39, 47, 53, 169.
Conacodon, 256, 258.
cophater, 258, 259.
entoconus, 258.
BULLETIN 169, UNITED STATES NATIONAL MUSEUM
concordiarcensis, Prodiacodon, 33, 46,
112 seq.
Condylarthra, 34, 60, 61, 173, 216 seq.,
267, 268.
Conoryctes, 50, 53, 169.
comma, 34, 39, 47, 53, 169.
species undetermined, 40, 47, 50.
Conoryctidae, 169.
Conoryctinae, 169.
conus, Microcosmodon, 83.
conventus, Neoliotomus, $3, 102.
Cope, E. D., 7, 71, 127,,170, 176,,.216-
218, 224, 233, 246, 265, 267, 268.
cophater, Conacodon, 258, 259.
Coriphagus, 53, 173, 220, 256, 257 seq.
encinensis, 259, 260. ‘
montanus, 9, 34, 48, 255, 257, 259,
seq.
corrugatus, Claenodon, 174-181.
Coryphodon, 222, 223, 266.
Coryphodontia, 265.
Coryphodontidae, 266-269.
Coryphodonts, 220, 265.
Crazy Mountain Field, Mont., 14, 55.
Crazy Mountain Syncline, Mont., 14.
Crazy Mountains, Mont., 9, 12, 14, 22-
26, 28.
Crazy Peak, Mont., 12.
Credneria daturaefolia, 57.
Creodonta, 170 seq., 224.
Crocodiles, 36, 59.
cuneata, Populus, 57.
cupanoides, Phyllites, 57.
cuspidata, Eudaemonema, 33, 47, 131
seq., 134.
Cynodontomys, 128-130.
Cypress, bald, 58.
danae, Fusconaia, 17.
daphnogenoides, Populus, 57.
daturaefolia, Credneria, 57.
dawkinsianus, Viverravus, 208.
declivus, Nedionodus senectus, 59.
Deltatheridiidae, 33, 60, 61, 107 seq.,
112:
Deltatherium, 172, 192, 193.
depressidens, Paromomys, 33, 47, 66,
147, 154 seq., 157, 159, 164.
Dermoptera, 131.
Deuterogonodon, 53, 62, 173, 190 seq.
montanus, 5, 37, 47, 49, 191, 192.
species undetermined, 37, 47, 192.
Diacodon, 111, 112, 117
Dichobunids, 230, 231.
Didelphodontinae, 107 seq.
Didelphodus, 106-111, 140, 258.
absarokae, 110.
Didymictis, 53, 67, 208, 209 seq., 214-
PAL OY
haydenianus, 34, 37, 38, 47, 49,
53, 209-211, 213.
microlestes, 34, 37, 47, 62, 209, 210
seq., 213.
protenus, 209, 210.
tenuis, 34, 47, 210, 212 seq.
diluculi, Bessoecetor, 33, 47, 122 seq.
Palaeosinopa, 122.
INDEX
Dinocerata, 265-268.
Dinocerea, 265.
Dinosaurs, 16, 17.
disceptatrix, Haplaletes, 34, 48, 66, 226—
228, 244 seq.
disjunctus, Litaletes, 34, 37, 47, 66, 226,
227, 234, 238, 239 seq.
Dissacus, 53, 216.
navajovius, 216.
species undetermined, 34, 47, 216.
dissentaneus, Litomylus, 34, 48, 66, 226,
227, 241 seq.
Djadochtatherium, 72.
Dogs, 180, 208.
Douglass, E., 6, 8, 9, 14-16, 21, 31, 38,
52, 70, 104, 135-138, 169, 196, 250,
257, 262, 269.
douglassi, Ptilodus, 33, 46, 67, 74, 75,
82, 83, 95, 96, 102.
dubius, Carpolestes, 162.
Eagle formation, 15.
Farle, C., 7% 127, 01717250217, 298;
225, 258.
Ectocion, 250-254.
Ectypodus, 51, 52, 65, 67, 73, 81-83,
99 seq.
cochranensis, 77, 82, 83, 100, 101.
grangeri, 33, 46, 67, 74, 75, 79, 82,
83, 99, 101, 102.
hunteri, 35, 46, 50.
musculus, 77, 79, 82, 83, 99, 101,
102.
russelli, 33, 46, 67, 74, 75, 79, 82,
83, 99 seq.
silberlingi, 33, 46, 67, 74, 75, 79,
82, 83, 97, 101 seq.
species undetermined, 83, 102.
elegans, Elpidophorus, 133.
Elftman, H. O., 71, 92.
Ellipsodon, 58, 225, 227-232, 233 seq.,
238-240.
acolytus, 53, 225, 227, 233, 234,239.
aquilonius, 34, 37, 39, 47, 62, 66,
227, 233, 234 seq., 238, 240.
inaequidens, 225-227, 233, 236, 238,
239.
lemuroides, 225, 227, 233, 234, 239.
priscus, 227, 228.
species undetermined, 41, 47, 238.
Elliptio priscus, 17.
Ellis, A. J., 26.
Elm, 58.
Elphidotarsius, 50, 51, 53, 68, 147, 161,
162 seq., 164.
florencae, 33, 47, 68, 163 seq.
Elpidophorus, 51, 53, 127, 129, 1380,
133 seq.
elegans, 133.
minor, 31, 33, 47, 49, 50, 133 seq.
patratus, 35, 42, 47, 50, 51, 133.
Emperodon, 107, 108.
acmeodontoides, 109.
encinensis, Coriphagus, 259, 260.
Mixoceclaenus, 257.
entoconus, Conacodon, 258.
Epanorthidae, 136.
281
Erinaceidae, 106, 111.
Eucosmodon, 52, 70, 72, 73,
92, 103 seq.
americanus, 83, 104.
americanus primus, 83, 103, 104.
gratus, 83, 104.
molestus, 83, 104.
sparsus, 33, 37, 46, 49, 83, 103 seq.
teilhardi, 83, 104.
Eudaemonema, 53, 106, 127, 129, 130,
131 seq., 140.
cuspidata, 33, 47, 131 seq., 134.
Euprotogonia, 246, 250, 253.
minor, 247, 253.
puercensis, 247.
subquadrata, 246.
europaeus, Glyptostrobus, 57.
europaeus ungeri, Glyptostrobus, 57.
Eutheria, 72.
excedens, Harpagosaurus, 59.
Falconer, H., 71.
Farr, M. S., 6, 8, 40.
Ferns, 58.
ferox, Claenodon, 39-42, 47, 49-51, 54, 55
174, 179, 180 seq., 182-185, 189.
Mioclaenus, 224.
Figs, 58.
Fish Creek, Mont., 12, 28, 40, 41.
Fish Creek beds, 16.
Fisher, R. A., 2, 260, 264.
Fishes, 59.
Fissipedia, 170, 207, 208.
Flora, 57 seq.
florencae, Elphidotarsius, 33, 47, 68, 163
seq.
floverianus, Mioclaenus, 246.
formosus, Halodon, 97.
Ptilodus, 97, 101.
Viviparus, 17.
Fort Benton formation, 14.
Fort Union group, 7, 15, 16, 20 seq.
fossilis, Onoclea sensibilis, 57.
Fox Hills formation, 16.
fraudator, Aphronorus, 33, 38, 47, 53,
62, 124 seq., 140.
Friant, M., 229.
Frontier formation, 15.
frugivorus, Phenacolemur, 35, 47.
furens, Prothryptacodon, 34, 38, 47, 194,
195 seq.
Fusconaia danae, 17.
Gallegos Canyon, N. Mex., 233.
Ganoids, 36.
Gelastops, 52, 106, 197 seq., 140.
parcus, 33, 46, 109 seq.
genetrix, Populus, 57.
Germann, J. C., 6.
Gidley, J. W., 3-6, 10, 21, 31, 32, 41, 52,
56, 67, 70-72, 78, 86, 90-92, 97, 101,
115-117, 141, 147-149, 154, 155, 159,
166, 168, 174-176, 180-185, 187, 189-
192, 194, 245-248, 250-253, 262, 269.
Gidley Quarry Mont., 9, 10, 22, 30, 31
seq., 35, 37-39, 46, 48-51, 55, 58 seq.,
68, 74-76, 93.
76, 81-83,
282
gidleyi, Nothodectes, 165.
Plesiadapis, 168.
Ptilodus, 33, 38, 46, 67, 74, 75, 82,
83, 95 seq.
Gidleyina, 5, 39, 50, 51, 55, 246, 250 seq.
montanensis, 5, 41, 48, 50, 251 seq.,
253, 254.
silberlingi, 40, 48, 50, 253 seq., 255.
species undetermined, 41, 48, 50.
superior, 42, 48, 254 seq.
Giebel, C. G., 171.
gillianus, Anisonchus, 258, 259.
Gilmore, C. W., 4, 6, 59.
Gingko, 58.
Glass Lindsay Lakes, Mont., 13, 23, 28.
Glendive, Mont., 57, 58.
Glyptostrobus europaeus, 57.
europaeus ungeri, 57.
gracilis, Cimolomys, 85.
Ptilodus, 70, 74, 84.
grandifoliolus, Sapindus, 19, 57.
Granger, W., 7, 10, 11, 70-72, 92, 141,
257.
grangeri, Ectypodus, 33, 46, 67, 74, 75,
79, 82, 83, 99, 101, 102.
Grasses, 58.
gratus, Eucosmodon, 83, 104.
Gray Bull formation, 16, 20, 21, 79, 81,
83.
Gregory, W. K., 107, 148, 170.
Grewia obovata, 57.
Grewiopsis platanifolia, 57.
Halodon formosus, 97.
serratus, 101.
Haplaletes, 51, 53, 226-230, 233, 241,
243 seq.
disceptatrix, 34, 48, 66, 226-228,
244 seq.
Haploconus, 256, 258.
Haplomylus, 225-228, 230, 231, 241.
speirianus, 226, 227.
Hares})'@.i3i:, 11.
Harlowton, Mont., 12, 40.
Harpagosaurus excedens, 59.
Hatcher: J? B.,1'6;
Hay, O- Ps, 59, 257.
Hayden, F. V., 7.
haydenianus, Didymictis, 34, 37, 38, 47,
49, 53, 209-211, 213.
Didymictis (Protictis), 209.
haydenii, Platanus, 57.
hazelae, Carpodaptes, 35, 47.
Hazelnut, 58.
Hell Creek formation, 15-20, 26-28, 55,
56.
Hemiacodon, 145.
Hemithlaeus, 221, 222, 256, 258.
Hickory, 58.
Horsetails, 58.
Hunter, Mr. and Mrs. F., 10.
hunteri, Ectypodus, 35, 46, 50.
Hyopsodinae, 241.
Hyopsodontid, aff. Haplaletes, 42, 48.
genus undetermined, 221.
Hyopsodontidae, 34, 60, 61, 66, 217,
220, 222, 223, 224 seq.
BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Hyopsodontids, 259.
Hyopsodontinae, 223, 225, 231, 241 seq.
Hyopsodus, 217, 223-226, 229-231.
paulus, 226.
Ictidopappus, 53, 208, 209, 213 seq.
mustelinus, 34, 47, 214 seq.
ignotus, Litolestes, 226, 227.
inaequidens, Ellipsodon, 225-227, 233,
236, 238, 239.
Tricentes, 225.
Indrodon, 127-130.
Insectivora, 33, 60, 61, 104 seq., 217,
2185-225. 229) 250
intermedius, Pantolambda, 34, 48, 270
seq.
Invertebrates, 58 seq.
Jepsen, G. Li, 6, 11, 20, 55;:79,¢83, 120,
141, 148, 147, 161, 162, 165, 225, 226,
229.
jepseni, Parectypodus, 38, 46, 74, 75,
82, 83, 100, 102 seq.
Judith River formation, 15-17.
Kingsbury formation, 11.
aahn re Lise
Knowiton, F. H., 9, 19-21, 56-58.
Kootenai formation, 14, 15, 29.
ladae, Leptacodon, 33, 46, 62, 113 seq.,
115.
Lance formation, 15-21, 55-57.
latidens, Claenodon, 34, 47, 176, 187
seq., 190.
Mimotricentes, 5, 34, 38, 47, 194,
205, 206.
Neoclaenodon, 187, 188.
Tricentes, 194, 203, 205.
latrunculus, Spanoxyodon, 34, 47, 68,
194, 203.
Laurels, 58.
Lebo Creek, Mont., 8, 13, 22.
Lebo formation, 9, 15, 16, 21 seq., 24-28,
3651305 ,0 0, nOlts
Leguminosites arachioides, 57.
Leipsanolestes, 113.
Lemoine, V., 7.
lemuroides, Ellipsodon, 225, 227, 238,
234, 239.
Mioclaenus, 225.
Lennep formation, 15, 16, 26.
Lepisosteus species undetermined, 59.
Leptacodon, 51, 52)) 67, 106; 111,» 112;
113 seq., 117.
ladae, 33, 46, 62, 113 seq., 115.
munusculum, 33, 46, 114 seq.
packi, 113, 114.
siegfriedti, 113.
tener, 35, 46, 50, 68, 113-115.
Leptictidae, 33, 60, 61, 106, 107, 111
seq., 120.
limnaeiforme, Campeloma, 17.
Lion Butte, Mont., 13, 24, 28.
Lioplax nebrascensis, 59.
Litaletes, 53, 226, 227, 231, 232, 238
seq., 245.
disjunctus, 34, 37, 47, 66, 226, 227,
234, 238, 239 seq.
INDEX
Litolestes, 51, 225-228, 241, 243.
ignotus, 226, 227.
notissimus, 35, 48, 227.
Litomylus, 53, 226 228, 233, 241 seq.,
243, 245
dissentaneus, 34, 48, 66, 226, 227,
241 seq.
Litotherium, 161.
Livingston formation, 8, 9, 16, 19, 26, 27.
Lizards, 59.
Lloyd, E. R., 11.
Lobdell, J. F., 11.
lobdelli, Psittaeotherium, 170.
Longman, H. A., 11
Loxolophus, 171.
Lull, R. S., 4.
Lupton, C. T., 26, 58.
lydekkerianus, Mioclaenus, 225.
Magnolia, 58.
mandibularis, Anisonchus, 262.
Maple, 58.
Marsh, O. C., 71, 217, 265, 268.
Marsupials, 70-72, 115-117, 128.
Matthew, W. D., 2, 7, 52, 64, 65, 70, 72,
105, 107, 111, 115-120, 127-131, 140,
141, 146, 169-177, 180, 194, 207, 209,
216-219, 222, 223, 225-227, 230, 232,
233, 246, 257, 258, 262.
matthewi, Pronothodectes, 33, 47, 165
seq.
maturus, Paromomys, 33, 39, 47, 62, 66,
147, 149 seq., 154-157.
mediaevus, Ptilodus, 52, 67, 70, 77-80,
82, 83, 85, 96.
Meek, F. B., 7.
Megopterna, 135, 136.
minuta, 9, 136-139.
Meinzer, O. E., 26.
Melville, Mont., 12, 14, 25, 40.
Melville formation, 15, 20, 21, 25, 27,
28, 39; 5D:
Meniscotheriidae, 216-218, 224.
Meniscotheriinae, 224.
Mesonychidae, 34, 60, 61, 170, 216.
Metachriacus, 53, 66, 172, 178, 192-194,
196, 197 seq.
provocator, 37, 38, 47, 49, 66, 194,
200 seq., 204.
punitor, 34, 47, 49, 62, 66, 194, 197
seq., 201, 202, 204.
species undetermined, 37, 47.
Metatheria, 72.
Miacidae, 34, 60,61, 170, 171, 182, 207 seq.
Miacinae, 207, 208.
Microchoerus, 144, 145.
Microcosmodon, 73, 81.
conus, 83.
microlestes, Didymictis, 34, 37, 47, 62,
209, 210 seq., 213.
Microsyopinae, 128, 129.
Microsyops, 127-130.
Mimotricentes, 52, 538, 173, 192, 193,
203 seq.
angustidens, 34, 36, 37, 47-49, 52,
194, 197, 205 seq.
283
Mimotricentes latidens, 5, 34, 38, 47, 194,
205, 206.
species undetermined, 36, 47, 48,
207.
minor, Elpidophorus, 31, 33, 47, 49, 50,
3 seq.
Euprotogonia, 247, 253.
Palaechthon, 159.
Palenochtha, 33, 47, 159 seq.
Tetraclaenodon, 249,
minuta, Megopterna, 9, 136-139.
Mioclaenidae, 217, 218, 225, 231, 232,
257.
Mioclaeninae, 218, 223, 225, 232 seq.,
257, 258.
Mioclaenus, 5, 216, 217, 224-228, 230-
233
acolytus, 225.
ferox, 224.
floverianus, 246.
lemuroides, 225.
lydekkerianus, 225.
opisthacus, 225.
turgidunculus, 225, 232.
turgidus, 224-227, 230, 232.
Mixoclaenus, 173, 255, 257, 258.
encinensis, 257.
Mixodectes, 5, 53, 70, 127-131, 133.
Mixodectidae, 33, 60, 61, 106, 127 seq.
Mixodectinae, 128, 129.
molestus, Eucosmodon, 83, 104.
Monotremes, ly wis 92.
montanensis, Claenodon, 34, 38, 47, 175,
176, 181 seq., 187-189.
Gidleyina, 5, 41, 48, 50, 251 seq.,
253, 254.
Myrmecoboides, 33, 47, 117 seq.
Neoclaenodon, 174-176, 181, 188.
montanus, Coriphagus, 9, 34, 48, 255,
257, 259 seq.
Deuterogonodon, 5, 37, 47, 49, 191,
194.
Ptilodus, 9, 33, 37, 38, 46, 52, 62,
67, 70, 74-80, 82, 88, 84 seq.,
95-97.
Mowry formation, 15.
multifragum, Psittacotherium, 34, 47,
49, 58, 68, 169 seq.
Multituberculata, 2, 33, 60, 61, 70 seq.
Multituberculate undetermined, 42.
munusculum, Leptacodon, 33, 46, 114
seq.
musculus, Eetypodus, 77, 79, 82, 83, 99,
101, 102.
Musselshell River, Mont., 12, 14.
mustelinus, Ictidopappus, 34, 47, 214
seq.
Myrmecobiidae, 115.
Myrmecobius, 115, 116.
Myrmecoboides, 10, 52, 106, 111, 112,
115 seq.
montanensis, 33, 47, 117 seq.
Nannopithex, 145.
nassau, Aspideretes, 59.
navajovius, Dissacus, 216.
nebrascense whitei, Campeloma, 17.
284
nebrascensis, Lioplax, 59.
Necrolemur, 144-146, 148.
Nedionodus senectus, 17, 59.
senectus declivus, 59.
Neoclaenodon, 173-176.
latidens, 187, 188.
montanensis, 174-176, 181, 188.
silberlingi, 175, 185.
Neoliotomus, 81.
conventus, 83, 102.
ultimus, 83.
Niobrara formation, 15.
nobilis, Platanus, 58.
notata, Aralia, 57.
Notharctinae, 147.
Notharctus, 217.
Nothodectes, 141, 164, 165.
gidleyi, 165.
notissimus, Litolestes, 35, 48, 227.
Nyctitheriidae, 33, 60, 61, 106, 118 seq.
Nyctitherium, 119.
Oak, 58.
obovata, Grewia, 57.
Omomys, 148, 161.
belgicus, 144.
vespertinus, 144, 162.
Onoclea, 58.
sensibilis fossilis, 57.
opisthacus, Mioclaenus, 225.
Protoselene, 225-227.
Ornithorhynchus, 71.
Osborn, H. F.,.:7) 215 73; 86;:127,:170-
172, 217-219, 225, 258, 266.
Osgood, W. H., 115.
Otter Creek, Mont., 13.
Owen, R., 71.
Oxyacodon, 225-230, 232, 233, 241, 248.
agapetillus, 225, 227.
apiculatus, 225-227.
priscilla, 225, 227.
turgidunculus, 225.
Oxyclaenidae, 171, 257, 258.
Oxyclaeninae, 170-173, 192 seq.
Oxyclaenus, 171, 172, 195.
packi, Leptacodon. 118, 114.
Palaechthon, 53, 142-145, 147, 148, 156
seq., 159, 160, 164.
alticuspis, 33, 47, 62, 156 seq., 159.
minor, 159.
Palaeosinopa, 52, 120-122, 124, 126,
140, 258.
diluculi, 122.
species undetermined, 35, 47.
Palenochtha, 53, 142-145, 148, 158 seq.
minor, 33, 47, 159 seq.
paleocena, Zanycteris, 136.
Palm, 58.
Pantodonta, 34, 60, 61, 265 seq.
Pantolambda, 11, 27, 58, ‘221, 222, 265,
266, 269 seq.
bathmodon, 269-271.
cavirictus, 41, 270, 271.
intermedius, 34, 48, 270 seq.
species undetermined, 34, 39, 48,
271.
BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Pantolambdidae, 34, 60, 61, 217, 219,
266-268, 269 seq.
Pantolambdids, 35, 40, 41, 48, 49, 50,
62, 218-220.
Pantolambdinae, 269.
Pantolambdodontidae, 269.
Pantolestes, 120, 121, 140.
Pantolestidae, 33, 60, 61, 106, 120 seq.
Pantolestinae, 121 seq., 124.
parcus, Gelastops, 33, 46, 109 seq.
Parectypodus, 52, 81-83, 99, 100, 102
seq.
jepseni, 33, 46, 74, 75, 82, 83, 100,
102 seq.
simpsoni, 77, 79, 82, 83, 102.
species undetermined, 83.
tardus, 77, 79, 83, 97, 1038.
Paromomys, - 50,,:51,2 53; 63;...66,.167,
142-147, 148 seq., 156, 157, 159,
162, 164.
depressidens, 33, 47, 66, 147, 154
seq., 157, 159, 164.
maturus, 33, 39, 47, 62, 66, 147,
149 seq., 154-157.
Paromomys, ef., genus and species unde-
termined, 42, 47, 156.
Paskapoo formation, 11, 81, 83, 130.
patratus, Elpidophorus, 35, 42, 47, 50,
ole ios:
Patterson, B., 11, 222, 266, 269.
paulus, Hyopsodus, 226.
Pearson, H., 78.
Peltosaurus, species undetermined, 59.
pelvidens, Chriacus, 197.
Pelycodus, 148, 156, 162, 217.
Pentacodon, 53, 106, 120, 121, 124,
Pentacodontinae, 121, 123 seq.
Periptychidae, 34, 60, 61, 216, 217,
220, 224, 255 seq., 266-268.
Periptychinae, 217, 223, 224.
Periptychines, 259.
Periptychus, 62, 216, 218, 221, 222.
Perissodactyla, 216.
Phenacodaptes, 225, 226, 229-231.
sabulosus, 226.
Phenacodontidae, 34, 60, 61, 216-218,
223, 245 seq.
Phenacodonts, 62.
Phenacodus, 54, 190, 191, 216, 223, 251.
Phenacolemur, 50, 146, 147.
frugivorus, 35, 47.
Phenacops, 107, 111.
Phyllites cupanoides, 57.
Phyllostomatidae, 134, 135.
Physa, 17.
canadensis, 17.
Picrodontidae, 33, 60, 61, 134 seq.
Picrodus, 53, 107, 134, 135 seq.
silberlingi, 9, 33, 47, 136 seq.
Pines, 58.
Plagiaulax, 70.
Plagiomene, 130.
Plagiomenidae, 130, 257.
planolatere, Viviparus, 59.
Plants, 56.
126.
219,
INDEX
platanifolia, Grewiopsis, 57.
Platanus aceroides, 19.
haydenii, 57.
nobilis, 58.
raynoldsii, 19.
species undetermined, 19.
Plateau Valley formation, 11.
Platychoerops, 164.
Plesiadapidae, 33, 60, 61, 148, 164 seq.
Plesiadapis, 50, 51, 53, 141, 144, 147,
164-166, 167 seq.
anceps, 35, 47, 50, 51, 156, 168, 169.
gidleyi, 168.
rex, 42, 47, 51, 156, 167 seq.
tricuspidens, 165.
Plesiolestes, 141, 148, 165.
Pleuraspidotheriidae, 218.
Pleuraspidotheriinae, 224.
pliciferus, Tetraclaenodon, 246-249, 253.
Polecat Bench, Wyo., 20, 27.
politus, Viverravus, 208.
Poplars, 58.
Populus amblyrhyncha, 57.
cuneata, 57.
daphnogenoides, 57.
genetrix, 57.
species undetermined, 57.
Porcupine Butte, Mont., 18, 25, 29, 41,
42, 57.
Potter Creek, Mont., 27.
Powder River Basin, Wyo., 11.
Prentice, S., 6.
primaevus, Arctocyon, 7.
Titanoides, 11.
Primates, 2, 10, 33, 60, 61, 127, 128,
83,
135, 141 seq., 217.
primus, Eucosmodon americanus,
103, 104
Princeton localities, Mont., 40, 46.
Princeton Quarry, Wyo., 55.
priscilla, Oxyacodon, 225, 227.
priscus, Ellipsodon, 227, 228.
Elliptio, 17.
Proboscidea, 265.
procyonoides, Claencdon, 176.
Prodiacodon, 52, 106, 107, 111, 112 seq.
concordiarcensis, 33, 46, 112 seq.
puercensis, 112, 113
Proectocion, 250.
Proglires, 127.
Pronothodectes, 50, 51, 53, 147, 162,
164, 165 seq.
matthewi, 33, 47, 165 seq.
Proscalops, 140.
protenus, Didymictis, 209, 210.
Prothryptacodon, 51, 53, 173, 192, 193,
194 seq., 199.
furens, 34, 38, 47, 194, 195 seq.
Protictis, 209.
haydenianus, 209.
Protochriacus, 171.
Protogonia, 216, 246.
subquadrata, 246.
protogonioides, Claenodon,
181, 186.
175-177,
285
Figueouee 5, 53, 172, 190, 191, 250,
251.
Protoselene, 225-232, 241, 251, 254.
opisthacus, 225-227,
provocator, Metachriacus, 37, 38, 47,
49, 66, 194, 200 seq., 204.
Pseudoloris, 161.
Psittacotheriinae, 169 seq.
Psittacotherium, 31, 53, 169 seq.
lobdelli, 170.
multifragum, 34, 47, 49, 53, 68, 169
seq.
Pterospermites, 57.
Ptilodontid undetermined, 35.
Ptilodontidae, 33, 60, 61, 73, 74, 80 seq.
Ptilodus, 10, 31, 52, 65, 67, 70-73, 81-83,
84 seq., 99, 161.
admirabilis, 84, 85.
douglassi, 33, 46, 67, 74, 75, 82, 83,
95, 96, 102.
formosus, 97, 101.
gidleyi, 33, 38, 46, 67, 74, 75, 82,
83, 95 seq.
gracilis, 70, 74, 84.
mediaevus, 52, 67, 70, 77-80, 82,
83, 85, 96.
montanus, 9, 33, 37, 38, 46, 52, 62,
67, 70, 74-80, 82, 83, 84 seq.,
95-97.
serratus, 101.
sinclairi, 33, 36, 46, 48, 52, 62, 67,
74-76, 78, 79, 82, 83, 96, 97 seq.,
101.
species undetermined, 33, 46, 83.
trovessartianus, 77, 82, 83, 96.
puercensis, Euprotogonia, 247.
Prodiacodon, 112, 113.
Tetraclaenodon, 34, 39, 48, 49,
246-248, 249 seq.
Puerco formation, 7, 11, 16, 18, 21, 46,
52-55, 81, 83, 173, 186, 191, 196, 224,
255, 259.
Puet Creek, Mont., 28.
pugnax, Chriacus, '36, 47, 48, 194, 196,
197.
punitor, Metachriacus, 34, 47, 49, 62,
66, 194, 197 seq., 201, 202, 904.
pusillus, Chriacus, 194, 197-199.
raynoldsii, Platanus, 19.
Red Lodge, Mont., 27.
Reed Point, Mont., 27.
Reptiles, 59,
retusus, Viviparus, 59.
rex, Plesiadapis, 42, 47, 51, 156, 167 seq.
Tetonius, 167, 168.
Richards, R. W., 26, 58.
Rodents, 127, 128.
Roger, O., aoe
Romer, A. Se
Russell, L. gs. v1. Nie O29; 190, LOL:
russelli, Ectypodus, oe) ‘46, Gteed4, 975;
79, 82, 83, 99 seq.
sabulosus, Phenacodaptes, 226.
Salix, species undetermined, 57.
San Juan Basin, N. Mex., 2, @; 00; Say.
224,
286
Sand Coulee formation, 16, 81, 83.
Sapindus affinis, 19.
grandifoliolus, 19, 57.
species undetermined, 19.
Sealops, 139.
Scarritt Quarry, Mont., 10, 25, 30, 34
seq., 39, 41, 46, 50, 51, 54, 55, 60,
Gls 63:
Schlaikjer, E. M., 139, 140.
Schlosser, M., 86, 115, 120, 217, 224,
257.
Scott, W. B., 86, 216, 217, 224, 225, 246.
sectorius, Anisonchus, 34, 37—41, 48, 50,
51, 53, 54, 255, 259, 261, 262 seq.
Sedges, 58.
Selaginella, 58.
senectus, Nedionodus, 17, 59.
senectus declivus, Nedionodus, 59.
sensibilis fossilis, Onoclea, 57.
Sentinel Butte formation, 25.
Sequoias, 58.
serratus, Halodon, 101.
Ptilodus, 101.
Shields River, Mont., 27.
Shoshonius, 127, 145.
siegfriedti, Leptacodon, 113.
Silberling, A. C., 3, 4, 6, 8-10, 17, 18,
21-23, 26, 27, 30-32, 34, 38, 40—42,
56, 70, 86, 98, 183, 168, 250, 251, 257.
Silberling Quarry, Mont., 9, 10, 29, 30,
31, 33 seq., 37, 39, 46, 48-51, 55, 56,
59-62, 68, 74, 75, 93.
silberlingi, Claenodon, 34, 42, 47, 176,
185 seq., 188, 189.
Ectypodus, 33, 46, 67, 74, 75, 79,
82, 83, 97, 101 seq.
Gidleyina, 40, 48, 50, 253 seq., 255.
Neoclaenodon, 175, 185.
Picrodus, 9, 33, 47, 136 seq.
simplicidens, Stilpnodon, 33, 47, 52,
68, 119, 120, 140.
Simpson, G. .G., 7, 54, 70, 71,-92; 107,
120, 121, 136, 161, 194, 225, 266.
simpsoni, Parectypodus, 77, 79, 82, 83,
102.
Sinclair, W. J., 6, 7, 11.
sinelairi, Ptilodus, 33, 36, 46, 48, 52, 62,
67, 74-76, 78, 79, 82, 83, 96, 97 seq.,
101.
Soricoidea, 104, 119.
Spanoxyodon, 53, 173, 192-194, 203.
latrunculus, 34, 47, 68, 194, 203.
sparsus, Eucosmodon, 33, 37, 46, 49, 83,
103 seq.
speirianus, Haplomylus, 226, 227.
Stanton, T. W., 3, 9, 16, 18, 21-23, 57.
Stehlin, H. G., 145, 146.
Stillwater River, Mont., 27.
Stilpnodon, 52, 119 seq.
simplicidens, 33, 47, 52, 68, 119,
120, 140.
Stone, R. W., 9, 16, 19, 21, 22, 24, 26, 27,
57
Stylinodontidae, 34, 60, 61, 169 seq.
BULLETIN 169, UNITED STATES NATIONAL MUSEUM
Stylomyleodon, 59.
subquadrata, Euprotogonia, 246.
Protogonia, 246.
superior, Gidleyina, 42, 48, 254 seq.
Tetraclaenodon, 254.
Sweetgrass County, Mont., 12, 14.
Sweetgrass Creek, Mont., 13, 41, 57.
Sycamores, 58.
symbolicus, Tetraclaenodon, 5, 34, 36,
37, 39, 43, 48, 49, 246 seq., 249, 255.
Taeniodonta, 34, 60, 61, 169 seq.
Taeniolabis, 71, 99.
Taligrada, 217-219, 265-268.
Talpid, 140.
Talpoidea, 104, 119.
tardus, Parectypodus, 77, 79, 83, 97, 103.
Tarsioids, 144, 145, 148.
Tarsius, 144, 146.
Teilhard de Chardin, P., 7, 148, 165.
teilhardi, Eucosmodon, 83, 104.
tener, Leptacodon, 35, 46, 50, 68, 113-
115
tenuis, Didymictis, 34, 47, 210, 212 seq.
Tetonius, 127, 144-146, 148, 168.
rex, 167, 168.
Tetraclaenodon, 5, 11, 39, 41, 43, 50—54,
190, 191, 216, 221-223, 246 seq.,
251-255.
minor, 249.
pliciferus, 246-249, 253.
puercensis, 34, 39, 48, 49, 246-248,
249 seq., 250.
species undetermined, 35, 42, 48,
250.
superior, 254.
symbolicus, 5, 34, 36, 37, 39, 43,
48, 49, 246 seq., 249, 255.
Theria, 72, 92.
Thermopolis formation, 15.
Thomson, A. C., 10.
thomsoni, Bessoecetor, 35, 47, 50, 122, 123.
Thryptacodon, 51, 53, 172, 173, 194, 195.
australis, 42, 48, 68.
Tiffany formation, 7, 11, 20, 54, 55, 81,
83, 112, 136, 141, 161;
Tilia weedii, 57.
Titanoides, 269.
primaevus, 11.
Tongue River formation, 25.
Torrejon formation, 7, 11, 46, 52-55, 62,
70, 74, 81, 88, 121, 128, 169-171, 173,
175, 176, 178, 180, 181, 185-187, 189,
196, 208-210, 218, 216, 224, 246-249,
255, 257, 262-265, 271.
Tricentes, 5, 11, 53, 171, 172, 192-194,
197, 203-205.
inaequidens, 225.
latidens, 194, 203, 205.
tricuspidens, Plesiadapis,165.
Triisodon, 171.
Triisodontidae, 171.
Triisodontinae, 170, 172.
Tritylodon, 71.
trochiformis, Viviparus,17.
Trogolemur, 146, 147.
INDEX 287
trovessartianus, Ptilodus, 77, 82, 83, 96. | Viviparus, 17, 58.
Tullock formation, 20. formosus, 17.
turgidunculus, Choeroclaenus, 226, 227. planolatere, 59.
Mioclaenus, 225, 232. retusus, 59.
Oxyacodon, 225. trochiformis, 17.
: : Walnut, 58.
eee seme Ia cen Walvoord, Lake, Mont., 13, 23.
Wasatch formation, 20, 21.
Uintalestes, 146, 147. Wiashalan 4
Uintatheres, 265, 266, 268. Weber ae
Uintatheriidae, 266, 267. Weed, W. H., 8, 57.
ultimus, Neoliotomus, 83. weedii, Tilia, 57.
ungeri, Glyptostrobus europaeus, 57. Wegemann, C. H., 11.
Unio, 58. Wetmore, A., 4, 6.
Unuchinia asaphes, 35, 47, 68. Wheatland County, Mont., 12.
Ursidae, 182. whitei, Campeloma nebrascense, 17.
Ursus, 185. Widdecombe Creek, Mont., 23, 28, 31,
vecordensis, Claenodon, 36, 47, 48, 176, 36, 38.
189. Wildeat Creek, Mont., 37.
vespertinus, Omomys, 144, 162. Wilmarth, M. G., 20.
Viburnums, 58. Woolsey, L. H., 26, 58.
Vitis xantholithensis, 57. Wortman, J. L., 7, 127, 170, 217.
Viverravidae, 208. xantholithensis, Vitis, 57.
Viverravinae, 170, 207, 208 seq. Xenacodon, 111, 112.
Viverravus, 53, 208, 209, 214, 216. Yellowstone River, Mont., 12, 14, 27.
acutus, 208, 209. Yew, 58.
dawkinsianus, 208. Zanycteris, 53, 134, 136.
politus, 208. paleocena, 136.
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