New suilline remains from the Miocene of Nebraska

Vol

,2

MEMOIRS

OF THE

CAKNEGIE MUSEUM.

VOL. II. NO. 8.

NEW SUILLINE REMAINS FROM THE MIOCENE OF NEBRASKA.

By O. A. Peterson.

In a paper laid before the American Philosophical Society on February 17, 1888,
Professor Cope proposed a new generic name for some Peccaries from the John Day
formation. From bis statement it appears tbat these Oregon forms agree in certain
cranial characters with Hyothervum von Meyer (Pctiseochcerus Pomel) of the Miocene
of Europe.

The material of this group known at present is still too imperfect, and in some
cases the descriptions are too brief, to determine the validity, or non-validity, of the
generic separations of Tftinohyus Marsh1 and Bothroldbis Cope.2 From the brief
descriptions and figures which Marsh gives of the two species Thiiwhyus lentus and
socia/is from the Jobn Day, the writer infers that that genus and Bothrolabis are
very closely related, if not the same. It is, however, best to await the discovery of
more complete material, before positively expressing an opinion as to the relations
between the different genera, which have been proposed by various authors. In
dealing with these suilline animals, ThinohyuS being the prior name used, I propose
provisionally to treat BothrolaMs as a synonym."

The object of the present paper is (1) to fully describe the principal characters of

i Amer. Jour. Sd., IX., p. 248, 1879.
*Prnc. Amer. Philos. Hoc, Vol. XXV., p. 66, 1888.

' W. J. Sinclair in a recent paper (Bull. Dept. Geol., Univ. Cal., Vol. IV., p. 135, 1905), lias already arrived at
similar conclusions.

305

306 MEMOIRS OF THE CARNEGIE MUSEUM

the porcine remains, which have been found in the Loup Fork Miocene of Nebraska
by the field parties of the Carnegie Museum, working from time to time in that
formation since 1901 up to the fall of the present year (1905) ; (2) to carefully com-
pare the osteological characters of the new material with those already known to
occur in the different species of the same genus from the John Day Miocene of
Oregon ; (3) it is intended, if possible, to more closely correlate and confirm the idea
of Mr. Hatcher as to the relationship of these two formations.4 By careful com-
parison and deduction it would seem that at least a portion of the Upper John Day
is represented in the lower horizons of the Miocene sandstones of western Nebraska
and eastern Wyoming.5

Thinohyus (B.) subjequans? Cope. (Figs. 1, 2 and 3.)
See Cope, Proc. Am. Phil. Society, Vol. XVIII., pp. 374-375, 1879 ; Vol. XXV., pp. 67-70, 1888.

This species is represented in the paleontological collections of the ( 'arnegie
Museum by a left mandible, No. 913. The specimen is doubtfully referred to the
above species. It was found in the lowermost Nebraska beds on the Niobrara
River, Sioux County, Nebraska. This horizon is undoubtedly of a much later age
than the uppermost John Day of Oregon. The ramus is not in good preservation,
but enough is present to determine its generic position. The following detailed de-
scription answers closely to that of Bothrolabis trickaenus* Cope, but as there is no
diastema back of p2 it is well to temporarily associate the specimen with B. sub-
aequans. If subsequent study of better material proves this determination to be
erroneous, the name T. brachyceps may be substituted.

The alveolar border for the incisors is entirely wranting, as are also the canine,
the first, (if there was a pj, and second premolars. P3 is damaged, p4 and
ma are complete. M2 is slightly broken, and m3 has lost its internal face. The
angle of the jaw is broken off. The alveolus for the canine indicates a very
robust tooth which corresponds perfectly to Cope's description. The alveolar
border is damaged just back of the canine, so that the absence or presence of
Pi cannot be certainly determined. Cope states that this tooth in B. subsequarts
has one root, and has diastemata before and behind it, but the writer is inclined
to think, in view of the considerably later age of the geological horizon in which
the Nebraska specimen was found, that this tooth may in this specimen have

'Proc. Am. Pliilos. Soviet)/, Vol. XLI , p. 118, 1902.

5 In a paper now under preparation by the writer more complete data summing up the paleontological evidence on
this question will be published. (See Annals Carnegie Museum, Vol. III., Part 4.)

6 Proc. Amer. Philos. Society, Vol., XXV., pp. 74-77, 1888.

PETERSON: NEW SULLINE REMAINS FROM THE MIOCENE OF NEBRASKA

307

been discarded in the process of modification. P2 is separated from p, by a short
diastema, and the tooth had two roots. P3 indicates a tooth with a compressed
simple crown. There is a considerable posterior heel and a slight cingulum on the
antero-internal face of the tooth. P4 has two main cusps, proto- and deuteroconids,
well appressed, forming a cross-crest anterior to the middle of the crown, as in

Fig. 1. Oblique internal view of left mandible of specimen No. 913, Carnegie Mus. Cat. Vert. Fossils
■' nat. size.

Fig. 2. External view of left lower mandible of specimen No. 913, Carnegie Mus. Cat. Vert. Fossils. 4 nat.
size.

( lope's description of Bothrolabis trichtrmis. Anteriorly on this tooth there is also a
small basal cusp and the cingulum on the postero-exterior angle of the tooth is
thrown into a short fold forming a minute tubercle. The elevated ridge on the
posterior heel, the metaconid, is perhaps more in the middle longi-
tudinal line than, according to Cope, seems to be the case in his
Both/rolabis trichamus. M : is a much worn tooth ; the wear of the
triturating face, however, indicates the usual quadri-tubercular
style of tooth. The antero-posterior diameter is but slightly greater
than that of P4. The anterior half of ma is damaged internally
and externally. The hypo- and entoconids are well separated on
the broad grinding face, and just back of these, at the posterior
border of the tooth, there is a small median cusp, the hypoconu-
lid. In the valley between the anterior and posterior cusps is a
swelling of the worn surface which indicates a small median conu-
lid. On the internal margin opposite to this cusp is a basal pillar
which fills up the bottom of the transverse valley. No other
evidence of a cingulum is present on the tooth. The antero-pos-
terior diameter of m2 is slightly greater than that of mx. The
increase of the antero-posterior diameter of all the teeth is very
gradual, as pa is only 5 mm. shorter than n^. Ma corresponds to that of Bothrolabis
trichserms which Cope described as having " two pairs of cusps and a large heel."
The paraconid can also be outlined on the tooth near the anterior cingulum. This

Fig. 3. Superior
view of left lower
mandible of specimen
No. 913, Carnegie
Mus. Cat. Vert. Fos-
sils. \ nat. size.

308 MEMOIRS OF THE CARNEGIE MUSEUM

cingulum is interrupted on the antero-internal angle by a separate minute conulid.
No other evidence of a cingulum is present on the internal side of this tooth. The
external face is broken off. The enamel is slightly mammillated on the internal
margin of the posterior heel ; otherwise the enamel is smooth. The different tuber-
cles of the heel are quite solidly fused together, leaving a broad triangular cross-
valley back of the two posterior cusps.

The symph}rsis of the lower jaw is quite heavy, and indicates that the mandibular
rami in this region were very broad. On the whole the ramus is rather short
antero-posteriorly and deep vertically. The masseteric fossa does not extend below
the line of the dentition and is indicated on the jaw fragment to be rather deep.

Measurements.

Total length of jaw fragment 129 mm.

Depth of jaw at P„ 35 "

" " " " M, 43 "

Length of molar-premolar series, approximately 100 "

" " premolar series, approximately 46 "

" " true molar Beries 54 "

Anteroposterior diameter of P3 12 "

f antero-posterior 14 "

Diameters of P* •<

( transverse 10

(antero-posterior 15 "

( transverse 11 "

M

f antero-posterior 17

( transverse 13

M3 antero-posterior 22

Thinohyus (Bothrolabis) siouxensis, n. sp.

The type of this species is based on a nearly complete skull and lower jaws (No.
1423, Carnegie Museum Catalogue of Vertebrate Fossils). The specimen was dis-
covered by Mr. J. Grim, Jr., and was presented by him to the writer. It was found
in the upper part of the Harrison horizon on the upper Niobrara River, Sioux
County, Nebraska. The specific name indicates the type locality from which it
came.

Some characters of the specimen might be regarded as of generic value, viz., the
absence of Px*, but it is thought best to await the discovery of more complete skele-
tal material before a final decision regarding its true affinities is had.

*The position and shape of the glenoid cavity and the posterior narial opening are similar to those in Platygonus
hptorhinus Williston.

1'ETERSON : NEW SULLINE REMAINS FROM THE MIOCENE OF NEBRASKA 309

PRINCIPAL SPECIFIC CHARACTERS,
/a C-f, Pi, M%. Occiput high. Region in front of thi orbit elongated, with even
slope of the skull, from the inion to the tip of the nasate; frontal region flat between
orbits, villi deep grooves leading pom, supraorbital foramina to very nearly threw! of the
nasals. The posterior margin of the orbit lies immediately in front of a line drawn verti-
cally from the anterior border of the glenoid cavity; the infraorbital foramen is large,
placed obliquely, and situated above the posterior part of P4. The posterior narial orifice
has an extreme posterior position. I'1 single-rooted and unite dose to thecanine, and
there is a space separating it from. P2. P- is in a coat in nous series with the teeth back
of it. P1 is absent.

CRANIUM.

The general contour of the cranium is quite similar to that of the peccary, Dico-
tyles tajacu (Linnaeus), especially the region anterior to the orbits. The comparatively
small size of the brain cavity, the high, sharp, and evenly sloped sagittal crest,
together with the simple premolars, are characters which are striking, and at once
separate this genus from the recent peccaries. The occiput is high and has a spoon-
shaped excavation above the foramen magnum. The lateral occipital crest is very
prominent. From the junction with the sagittal crest it descends outward and
downward for a short distance, then almost vertically downward nearly to the con-
dyle, diminishing in prominence in the latter direction, so that the surface of the
exoccipital is comparatively smooth 10 mm. above the base of the occipital condyle.
The posterior temporal ridge forms a weak junction with the lambdoidal crest half-
way between the occipital condyle and the inion. The strong posterior temporal
ridge points more strongly towards the conditions in the recent peccary and the hog
than to those seen in the John Day species, according to Cope's description of the
latter.

The base of the skull is injured. The occipital condyle is present, but the con-
tact is destroyed.7 The condyle is rather small and exhibits characters very similar
to those in the peccary. There was probably a moderately large-sized foramen
magnum, which separated the condyles proportionately less than in the peccary
and the hog. The baso-cranial axis has a much greater angle than is seen in Dico-
tyles tajacu. This is due to the position of the posterior Dares, which are relatively
much farther back in Thinohyus swuxensis than in Dicotyles.

The sutures in the cranium under discussion arc entirely obliterated so that the
outlines of the elements cannot be traced. The basioccipital is broken posteriorly.

'The condyle is restored in its approximate position with plaster.

310 MEMOIRS OK THE CARNEGIE MUSEUM

Anteriorly it apparently narrows rapidl}7, and there is a small rough tuberosity with
a narrow groove through it in the median line. The basi- and presphenoids evi-
dent!)7 have much less lateral extent than in recent genera, as the space between
the tympanic regions is quite narrow. The foramina opticum and rotundum are
close together ; the latter is quite large. Inferiorly the sphenoids send out strong
wing-shaped lamina?. These aire are firmly joined to the squamosal at the internal
base of the glenoid cavity and extend forward and downward, and obliquely out-
ward, to again form a strong contact with the posterior part of the maxillary and
the pyramidal process of the palatine. Some of the John Day species have a sim-
ilar structure in this region according to Cope.8 The region of the posterior nares
of Thinohyus siouxcnsis is one of the chief characteristics of the species. The pos-
terior exit of the orifice is between the anterior part of the tympanic bulla?, and its
almost vertical direction is indicated by the large swelling on the sphenoids at the
posterior boundary of the orbital fossa. In the peccary and Platygonus leptorhinus
this orifice is located well posteriorly, but not so far back as in Thinohyus siousensis.
The posterior narial border is divided anteriorly into three deep triangular
grooves ; one in the middle and one on either side of an osseous septum. The outside
grooves are bounded externally by the deep wall of the inferior ake of the sphenoids
referred to above. The foramen ovale and lacerum anterius are located at the an-
terior base of the tympanic bulla and are hidden from view by the extreme for-
ward extension of the latter. The entire occipital region of Thinohyus siuuxcnsis is
narrow in comparison with that of the recent peccary and the hog. The supraoc-
cipital continues upward apparently to the top of the occiput, uniting with the
parietal as in Sus scrofa Linnaeus and Phacochcerus aihiopicus Linnoaus. In the
peccary the supraoccipital does not extend so high and is met by the downward
curve of the parietal bones. The parietals in the fossil are irregularly convexo-
concave. Superiorly, they terminate in the sharp sagittal crest ; posteriorly they
are much extended, to help form the greatly overhanging occiput. The zygomatic
arch of the squamosal is very robust, especially behind. Below there is a well-formed
glenoid cavity, similar to that in Platygonus leptorhinus and the peccary, displaying an
oblique saddle-shaped surface like the glenoid cavity in some carnivora. Supero-pos-
teriorly the arch terminates in a high, transversely broad, and thin point, with the
apex gently rounded. At the base of this process (the origin of the posterior temporal
ridge) on the posterior face of the arch is located the rather small external auditory
meatus. Postero-laterally, the frontals show sharp and prominent temporal ridges.
These ridges terminate anteriorly in the rounded and somewhat elevated supercili-

*Proc. Amer. Philos. Soc, Vol. XXV., p. 72, 1888.

PETERSON : NEW SULLINE REMAINS FROM THE MIOCENE OK NEBRASKA 311

ary border. The postorbital process is more prominent than in the recent forms
and is trihedral in section. It terminates inferiority in a sharp point somewhat
posterior to the postorbital process of the jugal. The orbit is open posteriorly by a
space of 12 mm. between the apices of the processes on the frontal and jugal. The
posterior half of the frontals is flat and they are surrounded by the superciliary
borders laterally, and by the prominent temporal ridges posteriorly. Anteriorly
they gradually become convex to meet the maxillaries and nasals. The supra-or-
bital foramina are close together and the deep furrows which lead from them ex-
tend very nearly to the end of the muzzle.

The jugal has a considerable depth below the orbit, The postorbital process is
strongly developed. The latter is heavy antero-superiorly and tapers gradually on
the external and internal faces, forming a rather thin posterior edge. The process
terminates in a subacute point. The orbit is oblique, irregularly oval, and of con-
siderable size. On the anterior border the lachrymal tubercle divides the border
into two emarginations. The one above the process is shallow, but the one below
it is deeper, especially in the external face of the lachrymal. In this rounded
emargination is also located the lachrymal foramen. The zygomatic arch is not so
abruptly terminated at the lachrymal as in the hog, but continues in a gentle
sweep forward to meet the superior border of the maxillary. The temporal fossa
is proportionally much deeper than in the recent genera, while the orbital fossa is
of about the same depth. The spheno-maxillary foss;e in Thinohyus siouxmsis are
extremely deep, and divided by a thin septum of bone on the median line of the
cranium placed antero-posteriorly and vertically. The posterior opening of the
infraorbital foramen is large. The facial region of the skull shows no sutures.
The alveolar border is low, and does not extend as far back as in the peccary
and the hog. The deep fossa in front and below the lachrymal which appears
in Dicotyles tajacu is much less pronounced in Thinohyus siou.rensis. The fossa
in Thinohyus siouxensis is further forward. The infraorbital foramen is large,
obliquely placed, and situated above the posterior part of p*. The alveolus of
the canine presents, on the external face of the maxillary, an abrupt prominent
swelling. Back of this eminence is a faint horizontal ridge, which is an indication
of the much stronger ridge in the recent peccary. Immediately anterior to the
canine alveolus is the deep groove for the reception of the inferior canine.

The premaxillaries are heavy and greatly produced in front of the canine. The
anterior palatine foramina are separated by a strong bony ridge; they are round
and of considerable size. The posterior palatine foramina are close to the alveolar
border and are opposite the anterior part of m'a. The palate is long and narrow,

312 MEMOIRS OF THE CARNEGIE MUSEUM

very slightly arched, and has a lightly rugose surface. There is practically no dif-
ference in the width of the palate from i3 to back of m3.

The tympanic region is strongly supported by the postero-internal portion of the
squamosal. The tympanic bulla is of large size, filled with cancellous tissue, and is
closely appressed to the postero-internal angle of the postglenoid process. Anteriorly
the bulla overhangs the posterior nares in a peculiar manner, entirely hiding
from view the lateral borders of the orifice. The postglenoid foramen is situated on
the posterior edge of the postglenoid process, between the latter and the tympanic
region. The foramen lacerum posticum and the condylar foramen are close together
and are situated, the former internal to, and the latter immediately back of, the base
of the paroccipital process. The foramen lacerum posticum is at the posterior
boundary of the tympanic bulla.

MANDIBLE.

The lower jaws of the type are in good preservation, except the posterior part of
the angle which is broken off and lost. The rami are completely coossified leaving
no trace of the symphysis. The latter is long and curves evenly with the backward
sweep of the horizontal ramus. The latter as a whole, is rather long and slender,
diverging only slightly posteriorly, and has a short constricted area back of the
canine alveole. The alveolar border is nearly horizontal back of the diastema. The
latter has a considerable drop below the line of the border, causing on the
external face of the ramus a constriction similar to that in Dicotyles tajacu. The
external face of the alveolar border is reinforced by a rugose ridge extending nearly
the entire length of the border. This feature is also met with in the peccary. The
internal face of the horizontal ramus is slightly convex. The external surface is
divided posteriorly by a prominent rounded ridge, which disappears below p4, being
replaced by a smooth surface. The inferior border of the ramus forms a sinuous
line, as the angle has a considerable internal flexure. There are three mental
foramina almost in a horizontal line, and situated below and in front of p2.

The ascending ramus is strong, its anterior border, or base of the coronoid proc-
ess, has a prominent ridge extending well forward on the external face of the ramus
as stated above. The temporal fossa is deep ; it is of considerable antero-posterior
dimension, but does not extend below the line of the alveolar border of the jaw.
The top of the coronoid process is broken off, but the base at the sigmoid notch indi-
cates a rather broad antero-posterior surface. The mandibular condyle has a small
antero-posterior diameter, while the transverse diameter is considerable. The
coronoid process rises close to the anterior base of the condyle, forming a small
superior sigmoid notch.

peterson: new sulltne remains from the .miocene of nebraska 313
Measurements.

Length of skull from occiput to end of premaxillary bone 300 nun.

" from occipital condyle to eu<l of premaxillary bone, approximately 260 "

" " lambdoidal crest to postorbital process on tbe frontal 91 '

" " postorbital process on the frontal to end of premaxillary 215 "

Total length of alveolar border including premaxillary 156 "

Length of palate from posterior narial orifice to anterior end of premaxillaries 212 "

" " " " anterior border of posterior nares to the end of the premaxillaries.. 160 "

Greatest transverse diameter of occiput at lambdoidal crest 44 "

" " " of brain-case 49 "

" " " of frontals at postorbital processes 88 "

" " " of muzzle at lachrymal bone 85 "

" " " at end of muzzle -51 "

" " " of one condyle 21 "

Greatest diameter of cranium at tympanic region 69 "

Transverse diameter at glenoid cavity 119 "

" " of palate at m3 22 "

" " " p2 22 "

" " " i3 22 "

" " of muzzle at canines 58 "

" " " " " incisors 35 "

Greatest length of mandible, approximately 195 "

Length of mandible from incisor alveolar border to base of coronoid process back of ni3.. 148 "

Length of symphysis 53 "

Depth of ramus in front of p2 28 "

" " " back of m:) 45 "

SUPERIOR DENTITION.

Plates X X X I V.-X XXV.

Unfortunately the incisors, canines, and premolars one and two are lacking in
the type. The alveoli are all preserved and indicate a. large pair of median and
smaller lateral incisors; a heavy canine with the antero-posterior diameter greater
than the transverse, the alveoli heing oval in outline. The alveolus for p1 is
subovate, with the greatest diameter antero-posteriorly ; it is close to the canine
alveolus and on a line with the internal border of that tooth. P1 was undoubt-
edly single-rooted. P2 is separated from p1 by a diastema of 5 mm. and has
two roots as is indicated by the double alveolus. It had very nearly the same
antero-posterior diameter as p3. The latter tooth is firmly implanted in the maxil-
lary by three roots. The antero-posterior diameter is a little greater than the trans-
verse and the tooth has an oblique position. It is sub-triangular in outline with the
apex antero-internal. The protocone is prominent and the posterior cingulum is
modified into a broad ledge with the greatest diameter postero-internal. The tooth

314 MEMOIRS OF THE CARNEGIE MUSEUM

is entirely surrounded by a heavy cingulum. The enamel is smooth. P4 is wider
than long, as in Thinohyus pristinus Cope. The triturating surface of the tooth is
worn down, but indicates a single external cusp, the protocone. The deuterocone
is also strongly developed, and there are heavy anterior and posterior cingula. There
is an external cingulum, while the tooth is smooth on its internal side.

The first and second superior true molars are much worn. The grinding surface
of the former is in its worn condition a large basin surrounded by heavy enamel.
The cones are entirely obliterated, but the external remnant of the transverse valley
indicates a quadritubercular crown. The cingulum on the postero-external lobe is
present, while that on the antero-external lobe is wanting. The internal face has
no cingulum. M2 has strong external and internal remnants of the transverse
valley, extending well in on the triturating surface presenting nearly an antero-pos-
terior 8-shaped basin. There is an anterior and posterior cingulum. Externally
the cingulum is weakly developed and internally the tooth is smooth. M2 has the
greatest antero-posterior diameter of all the teeth in the upper jaw. The para- and
protocones of m3 are well worn, but indicate that they were well separated and of
considerable size, especially the paracone. The meta- and hyjxjcones are of smaller
size and are closer together. The abrasion on this -tooth indicates the former pres-
ence of a metaconule. The anterior half of the grinding face is too much worn to
justify the statement that a protoconule was present. There is a heavy anterior
cingulum and a strong posterior heel. There is no internal cingulum, while the
external is faint. The tooth is broadest anteriorly and tapers rapidly on the exter-
nal face from the paracone to the evenly rounded heel. The internal border is an
almost straight antero-posterior line.

INFERIOR DENTITION.
Plate XXXIV.

All the incisors of the lower jaw and also the canine on the left side are want-
ing, i The right canine is present, but with the top broken off. This is a heavy and
almost vertically placed tooth, very deeply imbedded in the mandible. Its antero-
posterior diameter is greater than the transverse. There are shallow grooves on the
tooth, one on the internal and one on the external face. The anterior border is
narrow and evenly rounded, while the posterior border is broad and more angular,
thus presenting a sub-triangular cross-section. There is a deep oblique abrasion on
the posterior face caused by friction with the superior canine. Px is absent. There
is a long diastema from the canine to p2. The latter is in a continuous series with

PETERSON : NEW SULLINE REMAINS FROM THE MIOCENE OF NEBRASKA 315

the teeth hack of it and is implanted in the ramus by two fangs. The single pro-
toconid is greatly developed, taking up the principal part of the crown. Antero-
internally there is a minute cingular conulid ; while posteriorly the cingulum is quite
strong. The external and internal cingula are wanting or only faintly indicated.
P3 has, as in p2, only the large protoconid with the anterior cingulum heavier and
the posterior heel much better developed than in the tooth in advance of it. The
external cingulum is strong, and internally there is no cingulum, except on the pos-
tero-internal angle, which, together with the posterior ledge, forms a small basin on
this part of the tooth. On p4 the proto- and deuteroconids are closely fused, form-
ing a cross-crest, which is much worn in the type. There is a strong anterior base,
and the metaconid is situated almost on the middle of the posterior base. No ex-
ternal or internal cingula appear on this tooth. M1 is too much worn for accurate
description. There was evidently no external or internal cingulum on this tooth
M2 has the proto- and metaconids equally developed, while the paraconid is a
minute element. Posteriorly the tooth is nearly as broad as anteriorly, the hypo-
and entoconids being well separated. The posterior and anterior cingula are heavy.
The bottom of the transverse valley is filled up externally by the cingulum ; there
are no other external or internal cingula on this tooth. Molars one and two in the
mandible have a quadrate appearance, while m3 has a long sub-triangular form,
which is due to the greatly extended posterior heel. The proto- and metaconids of
the latter tooth are more elevated than the hypo- and entoconids. The postero-in-
ternal angle of the heel is again elevated, so as to form a broad transverse valley
back of the hypo- and entoconids. The heel is solidly fused. The open transverse
valley between the proto- and hypoconids is taken up medially by the hypoconulid,
as is indicated by the wear on the triturating surface. There is a heavy anterior
cingulum. No other cingula are present on this tooth.

Measurements.

Superior Dentition.

Total length of the upper dentition 155 ram.

Anteroposterior diameter of the three incisor alveoli 24 "

( antero-posterior 15 "

Diameters of the canine ■

( transverse 10 "

Anteroposterior diameter of molar-premolar series 105 "

" " " " the premolars 53 "

f antero-posterior 14 "

Diameters of p3 s

( transverse 12 '

f antero-posterior 13 "

" " P' ^

(transverse 17 "

316 MEMOIRS OF THE CARNEGIE MUSEUM

( antero-posterior 16

" " m' 1 ,c ..

( transverse io

I antero-posterior 1"

" " m2 -

( transverse 15

( antero-posterior 18

I transverse 18

Inferior Dentition.

Total length of the lower dentition 146

Antero-posterior diameter of incisor alveoli ou one side, approximately 12 "

(antero-posterior 12

Diajneters of canine , ,,

( transverse s*

( antero-posterior 11

Diameters of p„ -j „

( transverse &

( antero-posterior 13

( transverse 1

( antero posterior 1-1

( transverse 9

( antero-posterior 16

(.transverse i-J

( antero-posterior 18

(transverse Jo

( antero-posterior 23

" " m3 ' ,. „

( transverse 14

In the paleontological collection of the Carnegie Museum is another specimen,
No 1418, Carnegie Museum Catalogue of Vertebrate Fossils (see Fig. 4), which I
refer to the same species described above. The specimen was found on the Agate
Spring Stock Farm, Sioux County, Nebraska, by Harold J. Cook, Jr., and was pre-
sented by him to the writer. The specimen, having (although badly worn)
incisors, a canine, and premolars in the upper jaw, and canines, and all the pre-
molars in the lower jaw, supplements the type in important respects. Although
the skull is distorted, it gives the complete length of the premaxillary and the
nasals, which are damaged in the type. Anteriorly the nasals appear to be narrow,
and terminate in a short subacute point, which slightly overhangs the anterior
nares. In spite of the crushed condition of the skull it is possible to recognize char-
acters like those encountered in the type of TM/nohyvs siovaensis. In No. 1418, the
specimen under discussion, the excavations for the lower canines are deeper, and
the anterior palatine processes of the maxillaries, immediately anterior to the
canines, appear to be somewhat more constricted, than in the type. The distortion
may possibly be in part the cause of this appearance.

The animal was an old individual, as is plainly indicated by the extremely worn
condition of the teeth. The crown of the median incisor in its worn state has the
appearance of a large, short, subcircular cylinder, with a strong curved fang deeply

TETERSON : NEW SULLINE REMAINS FROM THE MIOCENE OF NEBRASKA

317

imbedded in the heavy premaxillary. The triturating surface is convex in all direc-
tions by wear. The external margin has received the greatest abrasion. I2 is less
worn, is much smaller than i1, and has a basal cingulum on the postero-internal
angle. I3 is the smallest of the scries. This tooth is more ovate in cross-section,
the antero-posterior diameter being the greatest. The crown is surrounded by
enamel which terminates posteriorly in an acute angle. There is no cingulum.
The principal wear is located obliquely on the anterior half of the crown. All
the incisors are divided by short diastemata. The canine of this species is very
heavy, rivaling that of Dicotyles Injur". In the fossil the cross-section of the tooth
is a more rounded oval than in the recent genus, but, as in the latter, the posterior
border is narrower than the anterior. There is a long gradual abrasion caused by
friction with the inferior canine on the anterior face, which terminates in a rather

Fig. 4. Anterior portions of the upper and lower jaws of specimen No. 1418, Carnegie Mus. Cat. of Vert. Fossil.
J nat. size.

blunt point, with traces of additional wear on the external face. Twelve mm.
above the point of the right canine, on the external face, is a peculiar broad open
abrasion, extending quite across the tooth antero-posteriorly. On the left tooth is a
corresponding abrasion not nearly so well defined. These rubbed surfaces may indi-
cate the habits of the animal, at least 1 cannot account for the wear, except by sup-
posing that the canine was used for rooting. I'1 is separated from the canine by
diastemata, a very short one in front and a longer one behind. This tooth is one
of the chief characteristics of this species. It is a small tooth with the single pro-

318 MEMOIRS OF THE CARNEGIE MUSEUM

tocone, which has received very little wear on account of the absence of p,. There
are no cingula, except on the anterior and posterior angles on the internal side.
The tooth is implanted in a single alveolus. The two roots are closely coalesced,
with a groove indicating the separation of the roots in the species of earlier Tertiary
times. The premolars and molars back of p1 are so badly worn that they present
no characters capable of description.

The fragment of the lower jaws which belongs to this specimen (No. 1418)
indicates an animal somewhat larger than the type. The ramus is somewhat
deeper and the diastema back of the canine is longer than in the type specimen.
The diameters of the teeth are practically the same as in the type. The principal
features of the fragment are the solidly fused chin and the absence of px, showing a
correspondence to the type. The canine reveals a long abrasion on the antero-
external angle which has removed part of the enamel, forming of the remaining
enamel a diamond-shaped surface at the summit of the tooth.

Measurements.

Length of skull from supraorbital foramen to end of premaxillaries 200 mm.

" " " " infraorbital foramen to end of premaxillaries 112 "

" " alveolar border from m1 to end of premaxillaries 108 "

Antero-posterior diameter of the incisors 27 "

(anteroposterior 10 "

Diameters of I1 -I

(transverse 9

(( (antero-posterior 7 "

(transverse 65 "

(anteroposterior 5, "

( transverse 5

(anteroposterior 14 "

canine at base -

( transverse 10

( antero-posterior 6 "

" pi i

( transverse 4

antero-posterior 13 "

transverse 10 "

DISCUSSION OF RELATIONSHIP.

It will be safest to await the discovery of more perfect material representing this
group of Miocene peccaries before expressing a {positive opinion as to their affinities.
There are two types of the genus Thinohyvs, a dolichocephalic and a brachycephalic.
Professor Cope separated Thinohyus deccdens, generically from other John Day
forms, giving as the principal character the absence of p2, which is found to be
erroneous.9 Judging from the description by Cope and Sinclair, and also from the

'Sinclair, Bull. Dept. of Geol., Cal. Univ., Vol. IV., p. 135, 1905.

PETERSON: NEW SULLINE REMAINS FROM THE MIOCENE OF NEBRASKA 310

illustration l0 by the latter author, it would seem that, aside from the erroneous defi-
nition of dental characters by (.'ope, this species is strongly characterized by its
short skull and its inflated facial region, and may, when additional material is
known, justify its retention in the separate genus Chsenohyus proposed for it by the
latter author.

Thinohyits siouxenm is easily distinguished from other known species by the
single-rooted p\ which has a short diastema in front and a somewhat longer dia-
stema behind; the unbroken sequence of p2 with teeth back of it; the extreme
posterior position of the posterior narial orifice; the large and anteriorly projecting
tympanic bullae ; the posterior position of the infraorbital foramen, i. c above back
part of p*, and the absence of p, . The skull of T. sioim mis is of approximately the
same size as that of T. rostraJtus Cope, but the latter species differs from the former
in important characters, viz., the two-rooted p1, which is separated from the canine
and p2 by diastemata ; the latter tooth also has diastemata in front and behind.
The molar-premolar series is relatively shorter, and the infraorbital foramen is
placed more in advance (above the middle of p8). In Thinohyus pristinus Cope px
is small and as in T. rostratus, two-rooted, "the anterior root nearly reaching the
posterior edge of the canine alveolus, . . . p4 is wider than long and has but one
external cusp." u M3 is longer than wide, which is due to the large heel. The
infraorbital foramen is located above the middle of p3, which is another character
showing similarity to T. rostratus. According to Sinclair T. pristinus is further
characterized by diastemata in front and behind px. T. trichsenus Cope hasp4 as
long as wide, " and [the tooth] has a sub-quadrate base." V1 P1 is small, one-rooted,
and separated from p2 by a short diastema. Premolars one and two in the mandible
are each separated by diastemata in front and behind. In Thinohyus subsequans
( 'ope the infraorbital foramen is nearly as far back as in T. siouxt nsis, i. e., above the
middle of p4 in the former, and above the posterior part of that tooth in the Latter
species. T. subxquans is further characterized by the small two-rooted p1, which is
"almost entirely within the superior canine."13 P4 is wider than long, as in T.
I>ristinus and T. siouxensis. In T. subxquans there are short diastemata anterior and
posterior to pvM In Thinohyus lentus Marsh ,:"' " px is separated from the canine and

10 L. c, Plate XVI.

"Cope, Proc. Amer. Philos. Sue., Vol. XXXV., p. 73, 1888.

'« L. c, p. 75.

13 Cope, 1. c, p. 69. (The tooth is located close to the posterointernal angle of the canine— 0. A. P.)

'♦The lower jaw No. 913in the Caruegie Museum Collection whioh is provisionally referred to this species is clearly
that of a short-faced type such as T. decedent.

" T. sociatis Marsh is imperfectly known. It is a John Day form of rather small size with mammillated posterior
cingulum on m»(?). (See illustration, Am. Jour. Sci., Vol. XLVIII., p. 271, Fig. 25, 1894).

320 MEMOIRS OF THE CARNEGIE MUSEUM

p2 by diastemata of respectively 8 mm. and 10 mm."16 Thinohyus osmonti Sin-
clair is characterized by the long diastema in front of p,, which is double-rooted
and in an uninterrupted series with the teeth back of it. '• P1 is a single-crowned,
double-rooted tooth, separated from the canine and p2 by diastemata." " The infra-
orbital foramen appears from the photographic reproduction given by Sinclair to be
above the posterior part of p3.

SUMMARY.

The study of the remains described above may be summarized as follows :

1. The animals represented by the specimens in the Paleontological Collection
of the Carnegie Museum are more modified than those representing the John Day
Miocene in other collections, and the former may, when more completely known
be regarded as new genera.

2. The horizon in which tbe remains were found is tbe upper part of the Harri-
son horizon, which is regarded by Hatcher18 as filling tbe hiatus between the Upper
and Lower Deep River Formations. Tbe uppermost Arikaree, or the Monroe Creek
horizon, which is regarded by the same author as equivalent to the Upper John
Day, has not as yet yielded any remains of peccaries. When such remains are
found in the lower horizons of the Miocene in this locality, they will undoubtedly
reveal characters more closely allying them to the John Day forms, thus differing
from Thinohyus siouxensis.

The writer wishes to express his thanks to Dr. W. J. Holland, Director of the
Carnegie Museum, for kind suggestions and assistance in the preparation of this
manuscript for the press.

The illustrations are from drawings made by Mr. Sydney Prentice.

Carnegie Mi'seum, November 24, 1905.

i« Sinc'air, Bull. Dept. of Geol. Cal. Univ., Vol. IV., p. 110, 1005.

17 Sinclair, /. c, p. 139.

>*Proc. Aner. Philos. Sue, Vol. XLI., p. 118, 19(12.

EXPLANATION OF PLATE XXXIV.

Upper figure. Right side of skull and lower jaws of Thinohyus siouxensis. (Type) No.
1423, Carnegie Museum Catalogue of Vertebrate Fossils.

Lower figure. Superior view of the mandible Thinohyus siouxensis. (Type) No. 1423.
Figures § natural size.

322

Memoirs Carnegie Museum, Vol. II.

Plate XXXIV.

THISOEY08 8IOUXENSI8 PSTEBSON.

EXPLANATION OF PLATE XXXV.
Figure on left. Superior view of skull of Thinohyus siouxcnsis. (Type) No. 1423, Car-
negie Museum Catalogue of Vertebrate Fossils.

Figure on right. Palate view of same skull. (Type) No. 1423. Figures \ natural size.

324

Memoirs Carnegie Museum, Vol. II.

Plate XXXV.

THISOHTUB 8I0UXEN8I8 PETERSON.