HAKVARD UNIVERSITY. iE BUR Av ¥ OF THE MUSEUM OF COMPARATIVE ZOOLOGY. 41434 neat eo Prd Loins (Caan. Be ¥. Re A Leo ean Foe oe = 7 an : : a 4 Pye ats Wi eo . ‘Win al, MAU AY Pyl agp ne ; 1 _ a } . 7 ; ' Ny ; i) : . : - 7 : ° - i —<_ = : = 7 bales i f = n 4 i £ | _ : 4 . , g . : | : 3 * " : i } | - . 7 j I P re - oz - | 4 : ii = 7 ve i : ; i : “ee i. : =. ' c ie ne . - : Ce a4 ! , ' ate ; , ; Any 7 ad ; ‘an . s anc ow a \ : | 7 : (eae f i i m a 7 : wi Ay ae eae _ ' : ' Ee i — lo THE DESEADO FORMATION OF PATAGONIA aie ca eye a Hes 2 ee eee Oe ear ys i be a A ve *CZI aged 9ag Ss *azIs [eInjeU g/t ‘QUIS lopuoios uINIaYy}OIA Jo [[NYs sy L The Deseado Formation of Patagonia Frederic Brewster Loomis, Ph.D. Professor of Comparative Anatomy Amherst College EIGHTH AMHERST EXPEDITION 1911 PUBLISHED UNDER THE AUSPICES OF THE TRUSTEES OF AMHERST COLLEGE 1914 ain, Btn apt be ‘ie ee EAGT Xe “Wik igs ¢ P4 hs at) Oa) i ae vd 7 ue . DAF ‘Tass? a ; + i CONTENTS CHAPTER PAGE I. Organization of the expedition—history of the work done in the WEsecad oO toOnmatlOM)..o5 ches Me ees oc oe Meise soo, aestete ee 1 II. Description of the Amherst locality—age of the overlying beds— age of underlying beds—age of Deseado.................... 6 Ill. Table of the animals—study of the feeding habits—character of the habitat—the origin of the elements of the Deseado fauna 19 IV. Systematic arrangement—the Litopterna, Eoproterotherium, Notodiaphorus, Deuterotherium, Protheosodon, Conioptero- therm, Hricoelodus, Proadianthus: ...........-+6.:-.-..- 28 V. Typotheria, Archaeohyrax, Plagiarthrus, Prohegetotherium, 53 Prosotherium, Propachyrucos, Phanophilus, Archaeophylus, Eutrachytherus, Argyrohyrax, Isoproedrium............. VI. Rhynchippidae, Toxodontia, Rhynchippus, Morphippus, Eu- REMIOPS eta ete UN Neri eco Vere cide, Ae at ERM, SA 86 VII. Leontinirdae, Leontinia, Ancylocoelus.....................-. 108 VIII. Nesodontidae, Proadinotherium, Pronesodon, Coresodon, Inter- HPS NESE PMS <=, +. ote 14s. acetate ie we © Se Oke ne e122 IX. Isotemnidae, Trimerostephanus, Pleurocoelodon, Lophocoelus, Hennconlholia: toned hoses Ao ae es eee ee eee 129 Xe omalodontotneria, Asmodeus. a. 4.....4. 402-22 .5 004-6 eye 134 Del. Astrapotheria,, Parastrapotherinits . oj. 6a) cc o/c es ere ne eh wo ae 142 geeky rothenrta why fOuneriitia ts ae silso feces Lae eeesk wee el. oe oe 156 XIII. Rodents, Cephalomys, Scotamys, Litodontomys, Asteromys, HE GSTEINONTY Siasn, acto PS ee re oe Pee arcane hyd SSR NE Se arses sty 185 XIV. Edentata, Proeutatus, Prozaedius, Stenotatus, Proeuphractus, Peltephilus, Palaeopeltis, Glyptatelus, Hapalops, Octodonto- Lienstiant, SMO cae. 2 ese eve cw settee Be aio whee. se, Maia 197 XV. Marsupialia, Pharsophorus, Notogale, Proborhyaena, Palaeo- thentes, Pilchenia, Callomenus, Pseuhalmarhippus, Parabderi- MV eb irdssehysornis. Woxorls)..;¢ce5 2. soc ess ae keds eee eee soo 225 Los ity Hina ere ape we ‘ tance a ri 1 pte Pl ont be yh oot sethiod 20 Oia 1 bs post) A ee em as a by ‘ ' ‘ indi hes hitiges OES! ce) a wt = 4 Bg velifoaon pitch nied) ert Tih: 4 ren a i) T « ted'o Spey any Tae bveultirnyhiendy at 1 cei Wie? tary Sb ( = : 0 ihe its ait 42h bw af ty Ss os i eee j 4 ‘aornined vail! ab qebted ny fe yi IM whined al - . atin wn fk duswvret | 6 deowighh cde nae ay » aretws 2 eyhVEl cit ae “i ; daaerdl Woh Sedat aed a ei? Qe 7 Vibha? cee Rives. ~winl git J . aly atvalyon dS! alive ALT ITE ad PREFACE The results of the Amherst Patagonian Expedition were divided into two parts, the general features, to- gether with the narrative, were reported in a separate volume entitled, ‘‘Hunting Extinct Animals in the Pata- gonian Pampas,”’ published in 1913. For this volume has been reserved the description of the material found and such conclusions as are directly derived from that ma- terial. The material on which this work is based has been prepared out and placed on exhibition at Amherst College. The material here described forms a unified body of data, which adds materially to our knowledge of the com- plete animals of the Tertiary period in Patagonia. There are beside this some small collections which offer some isolated new facts, but the working up of these has been reserved for the future for small articles, as the work may come to maturity. The field has only been touched and a vast amount of further work can be profitably done on the horizons im- mediately preceding and following the one described in this volume, after which an interesting study can be made on the evolution of a fauna which developed in a consid- erable degree of isolation. F. B. Loomis. March 18, 1914. - n el ° “ ; - 7 . aa s ms . _ ia ; . “ ~~ oe - : : >a. “ re : Panes : i — - , 4 a « w ise - : dh : - - ane . : 4 YR AE, gor iibywy* > ieee ett hepa tpt Sit ts ot eyecare hi . pihg it Ait ut yas aty weet a OE betes wae ay pe phe rh a4 thajani > born fat Presi cae is Gayl aeialvce Ett be ROE at tahelltiaee hein ited. iareitqae ott To PO ie i ti jive, Prabe. qany) oleedee Open nial wie 100 : rohit ; get froeuth oar Shekn oie lee A by. eat jess tie an i fyestey Tae iat: o i Te, tWiark: “) pieeye a. Hed le wditiveahy bil ib U ‘Cer Vere ty as Ot Mis scarey inh alin haf} sn a “ the length of those of Theosodon garrettorum, the vertebrae are 3 as long. I have assumed that the number of vertebrae would prove to be the same as in Theosodon. While the limb bones are 2 as long as in the Theosodon, they are relatively half again as heavy and with the processes much more developed. The greatest differ- ence is found in the tarsus which is only 3 as long as that of Theosodon, though relatively as heavy, and the foot was carried in a nearly plantigrade position the heel raised but a little from the ground, though the anticular ends of the metatarsals and the phalanges indicate that there was a considerable freedom of movement of the various ele- ments. The form seems to be fairly close to the ancestral types such as Lambdaconus of the Casamayor, the limbs of which, however, are entirely unknown, but I should expect that when found these earlier forms would prove to be approximately plantigrade. Coniopternium Ameghino Coniopternium Amegh., 1895 Bol. Inst. Geog. Argen., t. 15, p. 632. Coniopternium Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 453. The genus is based on a calcaneum and astragulus of the macrauchenid type, but of unusually large size. The real generic characters are not evident in the description, but the presence of these bones, and of three cervical verte- brae, which we also found, indicating a macrauchenid of about the same size, are evidence that a form larger than the Santa Cruz representatives will turn up in the Deseado beds, for which this name may be reserved. The material is described under the specific name C. andinum. TRICOELODUS 51 Adianthidae Ameghino This family is based primarily on the genus Adianthus of the Santa Cruz to contain some macrauchenid-like forms which, however, are of much smaller size, and differ- entiated by the narrow character of the teeth and their early tendency to hypsodonty. It seems to be a valid series of dwarf types, which are all scarce and known only by the most fragmentary remains. Two genera are de- scribed from the Deseado, Tricoelodus, peculiar in having the posterior lobe of the lower molars somewhat subdivided so that the tooth appears three-lobed; and Proadianthus, known only by premolars which however show an unusual development of the styles on the inner side of the teeth. Tricoelodus Ameghino Tricoelodus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 454- The genus is based primarily on the three-lobed char- acter of the molars, which is a secondary effect of an infold- ing on the inner side of the posterior lobe. They are rooted, but strongly hypsodont. The margins of the crescents are well developed and the “‘pillar’’ is a prominent feature in the posterior crescent. Tricoelodus bicuspidatus Ameghino T. tricuspidatus Amegh., loc. cit. above. The species is the only one known of the genus, and : its features are those of the genus. The SYOOGOE®) following measurements indicate the size, Pia ci lOWEE pin. 3'to Mm. 1, 25 mmi.; height of the pm. 3-m. I—natural size, after Ameghino. mandible under molar I is 12 mm. Proadianthus Ameghino Proadianthus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 455. This genus is known only by the last two premolars of the lower jaw, which are compressed and moderately high. 52 THE DESEADO FORMATION OF PATAGONIA The two crescents are markedly separated by a cleft from the external side of the tooth, opposite to which is a high denticle, made by the fusion of the two ends of the cres- cents where they come together. Proadianthus excavatus Ameghino P. excavatus. Amegh., loc. cit. above. . The species is based on the two lower premolars described above. I reproduce the figure given by Ameghino. The measurements are: length of pm. 3 and Fig. 23. Lower right 4, 10 mm.; height of mandible under pm. pm. °3 and 4—natural size, after Ameghino. A,°O mim. CHAPTER V TYPOTHERIA In the Deseado beds this group of running and hopping animals is well represented, making about 14% of the Amherst collection, and varying in size from a little larger . than a rat to larger than a sheep. The group all have the front teeth modified into cropping or gnawing types, which grow permanently from persistent pulps; and the back teeth also growing through the whole or a large part of life, and also rootless, the crowns being variously infolded to make grinding surfaces. The skull is flattened above, and abruptly truncated behind; the cranium being large and swollen, the facial portion broad above and excavated on the sides. The orbits are centrally located, of considerable size, and unbounded behind. The tympanic bulla is swollen and may be hollow or filled with cancellous tissue. This cavity of the tympanic is con- tinued above and expands in the upper part of the squa- mosum, making a swollen capsule on either side of the back of the cranium. The openings of the auditory meatus are well back and in a tubular growth of the periotic which is directed back, and upward in an entirely characteristic manner. The strong paroccipital processes project far below the base of the carnium. The concave palate is wide and carried well back behind the teeth ending in two strong pterygoid processes. The mandible is deep, especially the back portion; has a slender coronoid process, and a small rounded articular condyle which would seem to indicate a forward and backward motion of the jaws. On account of the agreement with these general features, I have placed among the Typotheria the forms which Ame- ghino classified as Hyracoidea. 54 THE DESEADO FORMATION OF PATAGONIA While agreeing in the above general features, there is great variation among the various forms. The first upper and lower incisor may be greatly enlarged or of normal size. There is a tendency for the third upper and lower incisor, the canines, and the first premolars to be reduced and disappear, and all intermediate grades are found. In the molars there is a regular tendency toward simplifi- cation; so that in the upper molars of the earlier forms there is a deep inner fold and a more moderate outer fold, either or both of which may disappear completely, though in one series the fold seems to have been accentuated instead of lost. The feet may be adapted to running or hopping. In the Deseado and Santa Cruz material, four series of modifications may be distinguished which I have desig- nated as families; (1) the Avrchaeohyracidae, primitive forms in which the incisors are little enlarged, with inner and outer folds on the molars, those on the inner side of the upper molars being very deep, bulla small, feet un- known; (2) Interatheriidae, first upper and lower incisors rooted and of moderate size, inflexions on both the inner and outer sides of the molars, bulla large, feet adapted to running; (3) Hegetothertidae, incisor 1 of upper and lower dentition greatly enlarged and rootless, molars simplified, bulla large, feet adapted to running or to hopping; (4) Eutrachytheridae, large forms with the first upper and lower incisor enlarged and rootless, the upper molars with the inner fold developed and bifurcated, bulla large, feet unknown. For comparison of the various genera, they are charted on page 55, the dental character being used, as but few have the skeleton known, which is especially so of the earlier genera. From the foregoing chart and the comparative figures of the upper and lower dentitions, the variety and at the same time the homogeneity of the 7'ypotheria is evident. The gnawing front teeth resemble those of rodents, espe- CHART OF TYPOTHERIA 55 AGE Formuta| CANINES | U. Mortars] Last 1.MoLar| Toes | Hegetotherium Santa Cruz | 3 1 4 3] vestigal | noinner 3-lobed cleft 3143 : fold Prohegetotherium| Deseado no inner | fold Pachyrukhos Santa Cruz |_1 9 3 3] lacking | no inner 3-lobed not 2033 fold cleft Propachyrucos Deseado _| slightly 3-lobed 3143 reduced Prosotherium Deseado I 0 4 3) lacking | simple inner 3-lobed slightly|pm. simple 2043 fold cleft Archaeophylus Deseado ? 1 43) rather deep inner large fold, slight outer one Interatherium Santa Cruz 3 143) vestigal |slight inner 2-lobed slightly 3143 and outer cleft folds Protypotherium |SantaCruz | 3 1 4 3 large deep inner 2-lobed slightly closed series 3143 and outer cleft folds i‘ Argyrohyrax Deseado 3143 large bifurcated inner fold Eutrachytherus Deseado 3 143) lacking |bifurcated 2-lobed 2143 inner fold Isoproedrium Deseado iat 2s} Archaeohyrax Deseado 3143! large deep inner 3-lobed 3143 fold, slight outer fold Plagiarthrus Deseado | 2-lobed Pras cially in the genera where the enamel is lacking on all but the front face, but this is entirely a parallelism and there is no evident phylogenetic relationship. As to affinities with the Hvyracoidea, Sinclair* has carefully balanced them and finds so little in common between the two groups *Princeton Expeditions Reports, Vol. VI, p. 7, 1909. 56 THE DESEADO FORMATION OF PATAGONIA Fig. 24. Comparative series of upper dentitions of Deseado and Santa Cruz Typotheria; a, Archaeohyrax patagonicus; b, Hegetotherium mirabile; c, Prosotherium garzoni; d. Pachrukhos moyani: e. Archaeophylus patrius; /, Interatherium extensum; g Protypotherium australe; h, Argyrohyrax proavus; 7, Eutrachytherus spegazzinianus—all natural size. LOWER TEETH OF TYPOTHERIA mop QIED on “I ry oo a & os eee ee aes a os r iloos Pe aan ae t oy oe Cae! n Sah SZ ene NN” Ps 4 Fig. 25. Comparative series of lower dentitions of Deseado and Santa Cruz Typotheria; a, Archaeohyrax patagonicus; 6, ee neti mirabile; c, Prosotherium garzoni; d, Pachyrukhos moyani; e, Interatherium sp.; f, Protypotherium australe; lagiarthrus clivus; h, Eutrachytherus spegazzinianus; 7, Isoproedrium solitatium—all natural size. 58 THE DESEADO FORMATION OF PATAGONIA that he makes them a separate suborder. I find certain features in common, like the lophodont dentition with the tendency toward hypsodont incisors, the inflation of the tympanic and the extension of this up into the periotic region, and the general arrangement of the basicranial foramena. On the other hand, there are also numerous features in common with the Toxodonts, and several pecu- liar to the group, so that I would feel that all the Notun- gulates are descended from the /Tyracoidea, and this group has developed its peculiarities in South America, retaining however a little more of the hyracoid aspect. The Archaeohyracidae are the most primitive of the Deseado forms, but as all the families are already separated before this time the Deseado genera can not be considered as the ancestral ones, though they seem to have retained more of the primitive features. The Interatherudae represent an offshoot line of develop- — ment in which the incisors are not much enlarged and the infoldings of the teeth remain. The genus Archaeophylus seems to be directly ancestral to the Santa Cruz genera Interatherium and Protypotherium. In the family [ege- totheriidae there is a strong tendency for the incisors to develop into very large gnawing teeth, while the lateral incisors, the canine and the first premolar, tend to drop out, and the molars become more simplified. Propachy- rucos seems to represent a hold over of the most primitive type of these. The Prohegetotherium and Hegetotherium have retained the less specialized feet and less advanced type of teeth, while Prosotherium has tended to the develop- ment of the hopping mode of locomotion, which is attained in Pachyrukhos later. There thus seem to be two series inside of this family. When the material is better known, it may be best to separate the two series. The Eutrachy- theridae have retained the complexity of molars united with a permanently growing incisor. They seem also to have developed into a series of comparatively large forms, "elTaYyOdAT, Jo v1auax) ZNID eJueS puL Opeasaq dy} Jo Ausso[AYyg “97 ‘317 MY ny S74 5 ; Peodoc i s. I Xoshy Dh Sa SH Soyyadhyovy Bas, ee Osa. Win .a4494269H uniays ofa bay org = kes shy? soo” Malay yp ws apur facts — snyphydoaryray ava! xvahy oavyoay znd) vj] UVC opvasa(y doh nuns v4 60 THE DESEADO FORMATION OF PATAGONIA which, as they have advanced, have developed a bifurcated fold on the inner side of the upper molars, which in its complete development makes the upper molars three-lobed, as is seen in the typical 7ypotherium, representing the end of the series up in the Pampean formation. These relationships may be expressed graphically as in fig. 26. ADAPTATIONS Most striking of all the typothere peculiarities, is the development of the first upper and lower incisor into per- manently growing teeth, having the enamel reduced to the anterior side only, making thus a self-sharpening tooth similar to that of rodents. Such teeth are characteristic of gnawing forms and would indicate that the form lived, in at least a considerable part, on bark and twigs. In the eating of such food and breaking up the wood cells for the contained protoplasm and _ starch, an immense amount of chewing is involved, followed by a rapid wear of the molars. This is met, as is characteristic in rodents and grass eaters, by the development of first high-crowned, then permanently growing molars. In acquiring the perma- nently growing tooth, some of the irregularities of the crown are lost, others which are deep-seated enough to affect the tooth even to the root are maintained, so that especially the external and internal infoldings become a _ persistent part of the tooth, having been impressed into the dental papilla. A further supplement to the resistant character of the teeth is seen in the development, in the most ad- vanced types, of a cement layer on the outside of the molars, a feature apparently also a part of permanently growing roots. The feet are generally those of a running type, but a single phylum has acquired the hopping habit. The above features seem to indicate a more special adaptation than grass feeding. From the aspect of the ARCHAEOHYRAX 61 whole Deseado fauna, we would seem to be dealing with the inhabitants of an arid area, where bushes have, in part at least, replaced the grass. The typotheres seem to me to represent a part of the fauna which lived by gnawing the bark and eating the twigs and leaves of bushes. This does not preclude the eating of grass also, but I do not see how they would have developed all their peculiarities by eating grass alone. The rodents are of such insignifi- cant size that they could hardly have monopolized this food supply, and the typotheres seem to have adjusted themselves to, and occupied the place of rabbits on our western plains; but went even farther in developing in great numbers and varieties. SYSTEMATIC DESCRIPTIONS Archaeohyracidae Ameghino This family is differentiated by the presence of enamel on all sides of the first incisor, by the unreduced condition of the lateral incisors, and by the small bulla of the mas- toid. These are primitive features. Ameghino considered this family to belong to the hyracoids; but, as explained earlier, I believe them to be true-7ypotheria, though less specialized than the other families. Archaeohyrax Ameghino Archaeohyrax Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 431. This interesting genus is known by a complete skull found by Ameghino and of which we found no duplicates. I insert a reproduction of the side view of the skull, and the dentition is shown in fig. 24 a, and fig. 25 a. The dental formula is }74>. Incisor 1 is a little larger than the other incisors. Each upper molar has a vertical groove near the anterior external margin. In each upper premolar (after the first) and molar, there is a central pit surrounded 62 THE DESEADO FORMATION OF PATAGONIA by enamel, which is opposite the internal inflexion, and in a young individual, is presumably connected with the fold. In the same way, the last three lower premolars and the lower molars each have an internal pit, adjacent to the external inflexion. With advanced age all the teeth show closed roots, another primitive feature. In spite of the closed roots, the full dentition, and the enamel on the incisor; and on account of the deep inflexions and the isolated pits, I consider this genus a specialized side line, retaining many primitive features, and expect to find the Fig. 27. Archaeohyrax patagonicus, after Ameghino—natural size. ancestor of the typotheres in some one of the related Casa- mayor genera. Ameghino described three species, A. patagonicus, which we have figured, and which has a length of 84 mm. from inc. 1 to m. 3 in both the upper and lower dentitions; A. propheticus, of the same size, but with the dental series closed; and A. concentricus of larger size, the three lower molars having a length of 38 mm. Plagiarthrus Ameghino Plagiarthrus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 436. This genus is known only by the lower premolars and molars, which are permanently growing teeth, composed of two subcylindrical cylinders almost entirely separated PLAGIARTHRUS 63 by the external and internal folds which almost meet in the median line. On the outside, each tooth is coated with a layer of cement. When better known it may prove that this genus, so specialized in the character of the teeth, does not belong in this family. Plagiarthrus clivus Ameghino P. clivus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 436. This species is represented by a single specimen from the Chico del Chubut, west of Puerto Visser, which pre- serves pm. 3 and 4 and the molars. The characters of this, the type Seecies) sare: those Of the "genusi yoo von igve: emolare 9 and he: tocal length’ of the fiveteeth isi) 42nd molars 2s natural size. 36 mm., and fig. 28 shows in natural size the various in- dividual teeth. Hegetotheriidae Ameghino This family includes a large variety of forms from the formations from the Deseado up to the Mt. Hermosa, but all agree in having the first upper and the first two lower incisors enlarged into strong gnawing teeth; in the reduc- tion or absence of in. 3, the canine, and premolar 1 of the upper and lower dentitions; in having the external face of the upper molars not inflexed; in lower molar 3 being three- lobed; and in the bulla being inflated and hollow. There are in the family two series of forms, at least, the one lead- ing to the running Zegetotherium, the other to the hopping Pachyrukhos, and the very little known form Phanophilus which may fit into one of the other series when better known. In the Deseado the following genera are assigned to the family. Prohegetotherium, like Hegetotherium, except that the last premolar and the molars have a vertical furrow near the external anterior margin. 64 THE DESEADO FORMATION OF PATAGONIA TI . e = rr, upper inc. 2 and 3 and lower inc. 3 vestigal, upper pms. not molariform, molars with a deep internal fold. Propachyrucos, 37q3, lower jaw only, similar to Pa- chyrukhos but have inc. 3, the canine, and pm. 1 present and only a little reduced. Phanophilus, upper molars only, but peculiar in having a strong external medial column. Prosotherium, Prohegetotherium Ameghino Prohegetotherium Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 424. This little known genus is characterized by the upper molars having an external furrow near the anterior margin of the tooth. Otherwise it is similar to Hegetotherium. Ameghino described a species where the external surface of the bones was sculptured ‘“‘like reptiles.”’ I do not see how, with the arrangement of the muscles usual to mam- mals, the sculpture could be similar to that of reptiles, and feel that this is due to conditions of weathering. We did not find this species, but did find a form which resembled it in general, but differed in being smaller and with the external furrow less developed. Prohegetotherium sculptum Ameghino P. sculptum Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 424. This species is characterized by the deep external fur- row on the upper molars. The measure given is 34 mm. for the length of the three upper molars. Prohegetotherium shumwayi sp. nov. Founded on a portion of the right maxilla, carrying pm. 2 to 4 and m. 1, found on the Chico del Chubut, west of Puerto Visser, by Waldo Shumway. The teeth are simple, with but a shallow external furrow near the anterior margin of the premolars Fig. 29. H. Shumwayi —natural size. PROSOTHERIUM 65 and molar. A film of cement covers each tooth and extends to the top of the crown. The form is smaller than P. sculptum. MEASUREMENTS Upper premolar 3, length 6 mm., width 3; mm. Upper premolar 4, length 7 mm., width 33 mm. Upper molar 1, length 7 mm., width 33 mm. Prosotherium Ameghino Prosotherium Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 426. In founding this genus, Ameghino says that lower pm. tis lacking, but our specimens show it present as a vestige, and also show no trace of lower inc. 3 against which Ame- ghino puts a question mark, making the formula > as given above. The upper molars are similar to those of Pachyrukhos except that they have an inner fold which has been lost in Pachyrukhos. Yhe premolars are unlike the molars. Lower molar 3 is three-lobed. The descrip- tion of the skeleton is given under the specific description of P. garzoni, and this shows a remarkable resemblance to the skeleton of Pachyrukhos, throughout, so that I have no doubt but that Prosotherium is the ancestor of Pachyrukhos, the changes in the teeth proceeding in the line of simplifi- cation which seems to be general in this order, and is in general characteristic of forms in which the teeth become rootless. Ameghino described four species, P. garzont, P. trian- gulidens, P. robustum, and P. quartum, the last two of which differ so little from P. triangulidens, that I can not consider them as independent species. Prosotherium garzoni Ameghino P. garzoni, Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 426. This, the most abundant species of typotheres, occurs in our collection from the Chico del Chubut, west of Puerto 5 66 THE DESEADO FORMATION OF PATAGONIA : Visser, fifteen times; and in one case the major part of a skeleton was found, consisting of the skull and jaws, verte- brae of each type, ribs, most of the fore limb, the pelvis and a hind limb. The animal as a whole is smaller than P. triangulidens by about 12%, and is of lighter build. The skull is rela- LD tively light and narrow, especially in the rear, where the swollen hollow capsules of the squamo- ; ; | sum bones come within yy ten millimeters of meet- Fig. 30. Left upper dentition; left lower dentition— ing medianly, whereas, in other species, they are twice as far apart. These hollow capsules are in this species the most marked, and in this genus even more developed than in Pachyrukhos. The lachrymal bone is larger ex- ternally than usual, the lachrymal duct opening about four millimeters in front of the margin of the orbit, and continuing to the margin by an open groove. In P. triangulidens, the duct is inside the orbit. The heavy maxilla makes a strong process for the zygomatic arch, extending fully half way back along this arch. The short, but fairly stout jugale has but a short contact with the maxilla. In the dentition, the premolar and molar teeth are covered with a thin film of cement, which is thicker on the outside of the upper teeth and on the inner side of the lower teeth. On the opposite sides of these teeth this film is so thin that it is often in part worn off. Specimen 3083 preserves three of the deciduous premolars. Pm. 2 is simple and could readily be taken for the corresponding permanent premolar, except that it is, as are all the decidu- ous premolars, rooted. Deciduous premolars 3 and 4, on Fig. 31. Left upper denti- tion No. 3083, showing decid- uous premolars. PROSOTHERIUM GARZONI 67 the other hand, have a marked inflexion on the inner side, giving them the appearance of permanent molars. ‘The series measures 31 mm. of which the deciduous premolars occupy just half. The mandible is deep, especially the posterior portion; has a very slender coronoid process; and a slightly rounded articular condyle, which is a little longer than wide, so Fig. 32. Left mandible—natural size. that it would seem to allow a forward and backward mo- tion of the lower jaw. The vertebrae are considerably crushed, but have in each case the characteristics of the corresponding verte- bra of Pachyrukhos. Of the humerus, the head and distal ends are preserved, indicating a rather long and slender bone, very like that of Pachyrukhos. About three-fourths of the ulna is present, and it is also long and slender, with a wide articular facet for the radius, which is entirely separate from that for the humerus. Two metacarpals show the same elongation of the limb, and the two phalanges preserved indicate a small front foot. 68 THE DESEADO FORMATION OF PATAGONIA Fig. 33. Left side of pelvis—natural size. The pelvis is elongated, slender and lightly built, indicat- ing the same characteristics in the whole hind limb. The femur has a small rounded head on a well marked neck. It is excessively long, longer than that of Pachyrukhos, and also FN Fig. 35. Patella— natural size. Fig. 34. Left femur— Fig. 36. Tibia and fibula natural size. —natural size. PROSOTHERIUM GARZONI 69 straighter. It is further distinguished by the third trochan- ter being swung onto the back side of the bone. ‘The tibia and fibula are separate throughout their en- tire length, in which this genus is in strong contrast to Pachyrukhos, where these two bonesare fused, both distally and proximally. The astragulus is also quite characteris- tic, the trochlear surface being entirely on the dorsal surface, and the condylar ridges being telatively low and flat. This. troch- je) es cesicaneum, lear surface is far from being symmetrical, astraewus anc cubow the inner ridge being much flatter and lower ““'S' than the outer. The head of the astragulus is rounded, on a long neck, and directed obliquely inward. The fibular facet for i the fibula is crescent-shaped and vertical Fig. 38. Astragulusfrom except that the small proximal end of the cres- cent flares out. The outline of the sus- tentacular facet is that of an acute ovoid, and is situated mostly on the neck of this bone. The ectal facet is roughly rectan- gular in outline, strongly concave, and is separated from the sustentacular facet by a deep groove. The calcaneum is of moderate size, has a narrow fibular facet, a broad ectal facet, and a moderately large sustentacular one. ‘The facet for the cuboid is slightly concave, and occupies the whole of the distal and of the calecaneum. The metatarsals are moderately long and rather heavy, not quite as long Fig.39. Right foot—natural and slender as those of Pachyrukhos. ioe The phalanges are also shorter and slightly heavier than those of Pachyrukhos. We found four proximal and four of 70 THE DESEADO FORMATION OF PATAGONIA the second series, all associated, which probably indicates the full number of the toes. The ungual phalanges are proximally narrow and high, then expand toward the tip, developing into marginal expansions. ‘There is but a trace of a cleft in the end of these ungual phalanges. MEASUREMENTS Skull, greatest length 99 mm. Upper dentition, length inc. 1 to m. 3 55 mm Upper dentition, length pm. I to m. 3 31) am Upper dentition, incisor 1, width 6} mm. Upper dentition, molar 1, length 6 mm. Upper dentition, molar, width 4; mm. Mandible, greatest length ; 82 mm. Lower dentition, length inc. 1 to m. 3 53 mm Lower dentition, length pm. I to m. 3 32 mm. Lower dentition, molar 1, length 6; mm. Lower dentition, molar, width 2) anim Third metacarpus, greatest length 28 mm. Pelvis, length front to back 83. mm. Femur, greatest length (computed) 93. mm. Femur, diameter of middle of shaft 9 mm. Tibia, greatest length go mm. Astragulus, length 14 mm. Astragulus, width It mm. Calcaneum, length 252 mm. Metatarsus ITI, length 32 mm. First phalanx of digit III, length 12 | mim. Ungual palanx of digit III, length g mm. To make the similarity of Prosotherium with Pachy- rukhos clearer, I have restored Prosotherium, figure 40, from which it will be seen that this genus is also a hopping form with a plantigrade hind foot and a semidigitigrade front foot. In general it compares very closely with Pachy- rukhos, but the limbs are shorter and the grade of speciali- zation is not quite as high. It is, however, very evidently the ancestor of Pachyrukhos. PROSOTHERIUM GARZONI ("907 jTeH) ‘azIS [einyeu €/I—UOz1es WINIIYJOSOIg JO UOI}eIOISIY ‘ov “By 72 THE DESEADO FORMATION OF PATAGONIA Prosotherium triangulidens Ameghino . triangulidens Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 427. . robustum, Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 427. . quartum Amegh., 1901, Bol. Acad. Nac. Ciene. Cordoba, t. 16, p. 371. aaj sinoielas, This species is similar to P. garzoni except for size, the forms running about 12% larger, and being heavier built. In this same line the upper and lower molars are relatively wider and heavier. The top of the skull also is wider. I have drawn carefully the skull and dentition so that the detail can be seen from the figures. Beside triangulidens, Ameghino described P. robustum, which, as far as I can see, differs only in being about 5% larger, which is well within individual variation, so I have considered it as a synonym. ‘The same is the case with P. quartum, which Ameghino distinguishes as being about the size of P. vobustum, and having lower pm. 1 present. The latter character we found also characteristic of P. gargont, so only size remains and | do not consider less than 10% enough by itself to make a species. MEASUREMENTS Skull, length 110 mm. Upper dentition, length inc. I to m. 3 57 mm, Upper dentition, length pm. 1 to m. 3 35 mm. Upper dentition, incisor 1, width 8 mm. Upper dentition, molar 1, width 4> mm. Six specimens from Chico del Chubut Propachyrucos Ameghino Propachyrucos Amegh., 1897, Bol. Inst. Geog. Argen. t. 18, p. 425. The genus is based on lower jaws, in which the characters of the premolars, the molars and the first two incisors, resemble those of Pachyrukhos; but in this genus the third incisor, the canine, and the first premolar are retained and but little reduced. Ameghino has described two species, P. smithwoodwardi, and P. aequilatus. PROSOTHERIUM TRIANGULIDENS “I Ww Fig. 41. Top view of the skull, palatal yiew—natural size 74 THE DESEADO FORMATION OF PATAGONIA Propachyrucos smithwoodwardi Ameghino P. smithwoodwardi, Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 425. We did not find this species, but I reproduce Ameghino’s figure of it, natural size. The length Fig. 42. P. smithwoodwardi after Ameghino, right of the dentition from inc. mandible—natural size. ® . I to m. 3.15 41 mm., hewn of mandible under m. I is 12 mm. Propachyrucos aequilatus Ameghino P. aequilatus, Amegh., 1901, Bol. Acad. Nac. Cienc. Cordoba, t. 16, p. 371. This species is based on the anterior lobe of each lower molar, being longer than the posterior. In size, molars 1 to 3 measure 24 mm.* Phanophilus Ameghino Panophilus, Amegh., 1903, Anal. Soc. Cienc., Argen., t. 56, p. 202. This genus is based on isolated upper molars, charac- terized as similar to Protypotherium, but having a pro- nounced median vertical column, instead of a groove on the external face of the upper molars, a character unique among typotheres. ‘The position of the genus with this scant information is uncertain. One species is described, P. dorsatus. Phanophilus dorsatus Ameghino P. dorsatus, Amegh., loc. cit. p. 202. In our collection, two isolated upper molars of this un- usual form occur, corresponding in size and pattern to the one described by Ameghino. The external column, as *P. crassus has been described, (loc. cit., p. 425,) based on pm. 2 and 3, of larger size than either of the foregoing but I do not think that the genus can be determined on so small a fragment. PHANOPHILUS 75 seen by fig. 42, is narrow and high. A single tooth measures 53 mm. from front to back, and 33 mm. in width. Specimen 3142 gen. and sp. ? This specimen is the mandible with the pared Ase Eternal milk dentition. The molars present suggest ““"" °”* Prosotherium triangulidens, but inc. 3 and the canine are present, and the first two incisors are not enlarged, so it would seem to represent a genus which I have not been able to identify. Molar 1 is bilobed and similar to that of Prosotherium. ‘The deciduous premolars are all present, all ee &, Fig. 44. Milk dentition, genus and species?—natural size. rooted, and all remarkable for their great antero-posterior elongation. Roots of the incisors and canine are present, that of the canine being the largest, and those of the incisors being about equal in size. This would suggest such a form as Protypotherium, were this genus represented in the Deseado beds. Interatheriidae The family is characterized by the incisors not being enlarged, by upper and lower premolars and molars being inflexed on both the inner and out sides, and by the inflated mastoid bulla being filled with cancellous tissue. The only genus referable to this family, from the Deseado beds, is Archaeophylus. Archaeophylus Ameghino Archaeophylus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 423. The genus is based on a skull which preserved most of the upper dentition except the incisors, and which shows the characteristics of the family in their inception. 76 THE DESEADO FORMATION OF PATAGONIA Archaeophylus patrius Ameghino A. patrius Amegh., loc. cit. (oo BY, We found no specimen of this inter- >s esting type, but I give a diagram of Fig. 45. Archa hylus pa- 1: : z f K trius afer Ameghino, righ. Ameghino’s type, which shows the char- upper dentition—natural size. yee Space acteristics of the species and genus. The length of the premolar-molar series is 27 mm. Eutrachytheridae Ameghino The family consists of larger forms than the other fami- lies, and is characterized by the upper molars having the inflexion bifurcated, so that the teeth are at least incipiently three-lobed. [I would place in the family the genera, Eutrachytherus, Argyrohyrax, and Isopoedrium. Eutrachytherus Ameghino Trachytherus Amegh., 1889, Act. Acad. Nac. Cienc. Cordoba, t. VI, p. 918. Trachytherus Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 623. Eutrachytherus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 429. This genus was first called Trachytherus, and when this was found to be preoccupied, changed to Hutrachytherus. Ameghino gives the dental formula as ~77>, but in my specimen which is a comparatively young individual, | find a small alveolus for the upper canine, which modifies the formula to >~4 >. In the first upper dentition found, incisors 2 and 3 were represented by alveoli only, but our specimen shows these teeth, and we find that they have enamel only on the outer face, making this genus more specialized in this respect than any of the other typotheres. The upper molars have the deep inner inflexion bifurcated, which makes the tooth three-lobed, a character which grows more marked the older the individual is. The pre- maxillae are high and bring the snout well forward. The nasals are lacking, but the bounding bones show them to EUTRACHYTHERUS Vi have been unusually broad and flat. The maxilla extends up to the nasals, and bounds the lower border of the orbit, and projects backward in a heavy overhanging zygomatic process. The lachrymal bone is large externally, with a large but low lachrymal tubercle just below which is found the lachrymal duct, opening just in front of the margin of the orbit. The frontals are short and wide, extending outward over the orbit in a strong postorbital process which bounds half of the rear of the orbit. The parietals, meeting medianly, rise in a strong sagittal crest. Unfortunately the back part of the cranium ts lacking. Fig. 46. E. spegazzinianus—1/2 natural size. From another specimen, which contained the brain cast, it is clear that the bulla was much inflated and hollow, and that there was an inflation in the upper part of the squa- mosum, as in Prosotherium, etc. One specimen with the facial portion badly weathered, but retaining enough to identify the species as /. spegasz- zinianus, preserved the brain case, so that it could be prepared out. The most striking feature of this brain is its relatively large size, E. spegazzinianus being an animal about the size of a sheep, and the brain is as large as that of the sheep, which is in strong contrast to what would be ex- pected of an Oligocene form. Compared with the herbiv- 78 THE DESEADO FORMATION OF PATAGONIA orous Oligocene oreodont, Eucrotaphus, an animal of approximately the same size, this brain is half again as large in every way. A second striking feature is the short compact character of the brain, the forebrain extending only a short distance in front of the exit of the optic nerves, and extending backward so as to cover most all of the cere- bellum. Thirdly, the cerebral surface is considerably con- voluted, comparable to the convolution of a pig’s brain. These features would indicate a specialization of the nerv- ous system, approximating that of the skeleton, and would indicate that this group had advanced in intelli- gence and activity beyond the grade of nervous develop- ment which is apparent in the contemporaries of the T-ypotheria. The relatively small olfactory lobes are entirely beneath the frontal lobes and are seen only on the side view, but as there is a large hippocampal lobe behind them, it would only seem proper to attribute to these animals a well- developed sense of smell. The frontal lobes are unexpect- edly large, and are not clearly bounded off from the parietal lobes. The occipital lobes are also well developed and make a large portion of the backward extension of the cerebrum. The large size of this area, together with the fact that the optic nerves are large, indicates a good visual development. The temporal lobes are also large and extend well down on either side. And, finally, below all the others, come the swollen hippocampal lobes which complete this large cere- brum. The cerebellum is small having neither considerable width or height, and being overlapped by the cerebrum. The optic nerves are represented by large projections leav- ing the twixt-brain well forward under the forebrain. The medulla is not clearly marked except to show that it, too, was of fair size. Just behind the hippocampal lobes, and connecting with the cerebellum appear two striking projections. These EUTRACHYTHERUS 9 a | Fig. 47. Cast of the brain; A, from above; B, from the side—natural size. Cer, cerebellum; F, frontal lobe; H, hippocampal lobe; Oct, occipital lobe; Op, optic nerve; 7, temporal lobe; x, cast of cavity in squamosal bone; Na, case of interior of nasal cavity. represent the two large cavities in the upper part of the squamosum which are so characteristic of typotheres. The two large cavities clearly opened into the brain case 80 THE DESEADO FORMATION OF PATAGONIA by a broad connection which is especially wide at the lower ends. I find no traces of a connection with the bulla as described by Sinclair for Pachyrukhos. Further down are two small knobs apparently also representing cavities in the squamosum, and also connected with the brain case. In considering the brain these should be overlooked; but they doubtless represent some nervous function to which I have as yet no clue. Ameghino considered that Eutrachytherus was the con- necting link between Archaeohyrax and Typotherium. 1 feel that this genus is too highly specialized to be a con- necting form, though it doubtless belongs to the series which ends in Typotherium; and such a form as Argyro- hyrax is more likely to be the really ancestral form. Two species are described, E. spegazzinianus, and FE. conturbatus, which is about 15% smaller. Our collection offers a third species, EZ. grandis, which is nearly 50% larger than the first named species. Eutrachytherus spegazzinianus Ameghino Trachytherus spegazzinianus Amegh., 1889, Act. Acad. Nac. Cienc. Cordoba, t. VI, p. 919. Trachytherus spegazzinianus Lydekker, 1894, Anal. Mus. La Plata, pt. 3, p. 2. Trachytherus spegazzinianus Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 622. Eutrachytherus spegazzinianus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 428. This species was founded on the anterior part of a skull with the full upper dentition. My specimen differs from Ameghino’s in having a tiny alveolus for the upper canine, the difference being due to my specimen being younger. The upper dentition is very characteristic. Incisor 1 is a powerful, deep-set, curved gnawing tooth, with a heavy layer of enamel on the anterior face, and none on the other sides; and is moderately beveled in the rear as a result of wear. The second and third incisors are much smaller, each having enamel on the outer face only, and EUTRACHYTHERUS SPEGAZZINIANUS 81 with a marked tendency to become vestigal. The suture of the premaxilla comes to the base of inc. 3. There fol- jiows a short diastema, then a tiny alveolus for the canine, closely followed by the first premolar which is also small. The second premolar shows no inflexion. Beginning with the third premolar there is a strong inner inflexion, which in the fourth premolar and molars is bifurcated. The molars are considerably larger than the premolars, the second being the largest of the series. With each succes- sive molar, the inflexion is wider, so that in m. 3 the tooth is divided into three lobes of nearly equal size. All pre- molars and molars are rootless, curved, and set so deep in the jaw that they almost meet in the median line. A typi- cal molar measures 50 mm. in length, of which only 7-8 Pe 35> Fig. 48. E. spegazzinianus, right upper dentition—natural size. mm. project above the border of the jaw. All the back teeth are covered with a thick coating of cement. The arrangement of the teeth of the lower jaw is shown in fig. 25 h., after Ameghino. The first and second incisors are greatly enlarged. Incisor 3 is lacking, and the canine vestigal. Pm. I is small and single-lobed, the succeeding premolars and molars being large and divided into two lobes by a deep external, and a shallow internal infolding. MEASUREMENTS Skull, width between the orbits 60 mm, Skull, width across the postorbital processes 88 mm. Skull, height from m. 2 to top of frontal 77 mm. Skull, width of palate opposite inc. 2 42 mm. Skull, width of palate opposite m. 2 62 mm. Dentition, length inc. 1 to m. 3 140 mm. Dentition, incisor I ant.—post. length 11 mm. width 16 mm. Dentition, pm. 3 length If mm. width 13 mm. Dentition, m, 2 length 22 mm. width 16 mm. 6 82 THE DESEADO FORMATION OF PATAGONIA Eutrachytherus conturbatus Ameghino Trachytherus conturbatus Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 623. Eutrachytherus conturbatus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 429. This species is founded on upper teeth, which are said to be relatively smaller anteriorly, and actually smaller throughout, by about 15% than are those of the preceding species. Molar I measures 17 mm. long by 9 mm. wide. Eutrachytherus grandis sp. nov. This species is based on upper molars 1 and 2 of the left side, from the Deseado beds, of the Chico del Chubut, west of Puerto Visser. The teeth are typically those of the genus and differ only from other species in their large size, being some 50% larger than the corre- sponding teeth of £L. spegazzinianus. Each is covered with a layer of fully half a millimeter of cement. Fig. 49. E. grandis, molars of the left side—natural size. MEASUREMENTS Upper molar 1, length 29 mm., width 21 mm. Upper molar 2, length 303 mm., width 18 mm. Argyrohyrax Ameghino Argyrohyrax Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 435. The genus is distinguished by the full dentition in closed series, and by the upper molars having a deep internal inflexion which is bifurcated, making the teeth at least incipiently three-lobed. Incisor 1 is relatively somewhat wider than in the preceding genus. It seems to me that it is from such a genus that 7ypotherium arose, by the reduction of the lateral incisors, the canine, and the first ARGYROHYRAX 83 two premolars, and by the increase of the bifurcated in- ternal fold. Three species have been described, A. pro- avus, the type species, A. acuticostatus, of a little smaller size, and A. proavunculus of still smaller size. Argyrohyrax proavus Ameghino A. proavus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 436. This species occurs three times in the Amherst collec- tion. The best specimen has pm. I, 3, 4, and m. I and 2 of the upper jaw. The species is characterized by a nar- row furrow near the anterior external margin of the pre- molars and molars; and by pm. 3 and 4 and the molars Fig. 50. Right upper dentition, the outline teeth after Ameghino— natural size. having a deep internal bifurcated inflexion, which tends to make these teeth three-lobed. The genus is known only by the upper dentition, and while I did not find any associated lower teeth, I believe that some one of the genera known only by the lower den- tition, like Plagiarthrus, is that lower dentition. MEASUREMENTS Upper dentition, length inc. 1 to m. 3 (@ Ameghino) 71 mm. premolar 1, length 7 mm., width 4 mm. premolar 3, length 7 mm., width 6 mm. premolar 4, length 8 mm., width 6 mm. molar 1, length 8 mm., width 6; mm. Argyrohyrax proavunculus Ameghino A. proavunculus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 436. The species is simply said to be much smaller than the preceding, which, by the measurements, would figure out about 27%. The measurements given are pm. I to m. 3, 33 mm. 84 THE DESEADO FORMATION OF PATAGONIA Argyrohyrax acuticostatus Ameghino A. acuticostatus Amegh. 1901, Bol. Acad. Nac. Cienc. Cordoba, t. 16, p. 361. This species is described as differing from A. proavus in being somewhat smaller, but I find it about the same size. The specific character is in the teeth being more compressed, and in the anterior vertical margin of the upper molars being developed in the form of a very salient CrESE. Isoproedrium Ameghino Proedrium Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 623. Proedrium Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 431. Isoproedrium, Amegh, 1903, Anal. Soc. Cient. Argen., t. 56, p. 18. This genus is based on a toothless mandibular sym- physis of large size, on which the second incisor is indicated as larger than the first. We found one lower jaw, which, though imperfect, confirms the above as a genus and adds the following for generic characters; premolars with a shallow inflexion on the inner and outer sides, the molars with a shallow inner, and a narrow deep outer inflexion, heavy layer of cement on the premolars and molars, enamel reduced on the anterior internal, and the posterior internal corners of at least the premolars. Isoproedrium solitarium Ameghino loc. cit. above. I have assigned the specimen shown in fig. 51 to this species. Alveoli of the first and second incisors show inc. Fig. 51. Right mandible, dotted line indicated alveolus—natural size. 2 considerably larger than inc. 1. About the third incisor and the canine my specimen shows nothing, being broken ISOPROEDRIUM 85 down in that region. Pm. I is represented by a moder- ately large alveolus, 10 mm. long. Pm. 2 is 13 mm. long by 10 mm. wide, and slightly constricted medianly as far as the enamel is concerned, the furrow in either side being filled with cement. Pm. 3 is 18 mm. long by 12 wide and similar. There is only an alveolus for pm. 4, which is 23 mm. long. M. I is incomplete, but was about 23 mm. long by 10; mm. wide and is distinguished by the deep outer inflexion. Each tooth present is covered with a heavy layer of enamel nearly a millimeter thick; and each of the teeth is unique in that the enamel is wanting on the anterior internal and the posterior internal corners of the teeth. CHAPTER VI ‘TOXODONTIA THE toxodonts of the Deseado are much more varied than those of the Santa Cruz, and less so than those of the Casamayor; the teeth less hypsodont than in the Santa Cruz, and more hypsodont than in the Casamayor; are smaller than those of the Santa Cruz, and larger than those from the Casamayor. It isa group of heavy, short-limbed, nonadaptive animals, which, as time and competition pro- gressed, gradually diminished in numbers and variety. The ancestral type must be sought in some such a form as Henricosbornia, where the upper molars are brachydont, have the four primary cusps distinct, and the connecting crests of small size, and a cingulum moderately developed on the front and rear sides. Progress is in the line of en- larging the crests, so that, in the later forms, the two exter- nal cusps are united to make a wall; and the anterior external and the anterior internal cusps are united into the large anterior lobe; while the posterior external and the posterior internal cusps unite to make the posterior lobe. These may remain relatively simple as in Rhynchippidae* ; or with this simple arrangement of the cusps, the cingulum may be developed into a platform around the anterior, inner, and posterior sides of the molars, as in the [sotem- nidae; or, with relatively simple molars, the incisors may be specialized into caniniform-like teeth as in the Leon- tiniidae; or secondary processes (or cristae) may develop from the wall, making the complicated teeth characteristic of Nesodontidae. + | have abandoned the family term Nolohippidae, as the genus used as a basis is very little known, and the forms Ameghino assigns to the family, to my mind, mostly belong with the Nesodontidae. TOXODONT TEETH 87 For convenience in discussing the modifications of the toxodont tooth, I have, throughout, used the nomenclature ilustrated in fig. 52, taking one of the most complicated to show the ultimate development. In the upper tooth there is, first, the external wall, from which springs the anterior lobe, always the larger lobe, and composed of the protocone and paracone of Osborn. In the rear is a smaller narrower pos- terior lobe, composed of the hy- pocone, the metacone, and the metaconule of Osborn. Between these is a large basin, which may be subdivided by two cristae into secondary bays, referred to as bays 1, 2 and 3, while the cristae are in the same way referred to as cristae ITand2. Insome genera, the cristae are entirely wanting, in others in- soon; 2, Tower molars, somewhat eipient When f ully developed, they are most marked in young individ- uals and, as the tooth is worn, appear progressively shorter. Behind the posterior lobe, there is a variable bay, number 4 which is bounded behind by crista 3, which is apparently a development of the posterior cingulum. This last crista and bay may or may not be present. The lower molars of toxodonts are all on the same plan, each tooth being composed of two crescents, the anterior and posterior. The ends of these crescents are referred to as the anterior, median and posterior horns. The bay in the anterior crescent is simple and usually disappears with the wear of the tooth without making a pit. In the centre of the posterior crescent is the pillar or posterior tubercle which Scott has found to be characteristic of these South American Ungulates. It is, to my mind, the same as the lobe Posterior vista 3 88 THE DESEADO FORMATION OF PATAGONIA mesostylid of the Fayum hyracoids. Between the pillar and the median horn, I find a narrow vertical ridge, which I have termed the septum; and which tends to unite with the pillar inclosing a small bay, usually seen in worn teeth as a pit. The bay between the septum and the median horn is designated bay 2, and this quite generally appears in a worn tooth as a pit (2). The bay between the septum and pillar is designated bay 3, and is usually seen as a tiny pit, which however does not extend as deep into the crown as the other pits and is usually lost when the tooth is about half worn off. ‘The bay between the pillar and the posterior horn is numbered 4, and is usually open, though in a worn tooth it also may appear as a pit. The effect of wear is shown by comparing B and C in fig. 52, the latter being the same tooth sectioned a little below the middle. I find in studying a lower molar of Coresodon that bay 3 becomes a pit after some 6 mm. are worn off, while bays 2 and 4 remain open until some 10 mm. are worn off when they also become pits. Pit 3 will disappear when I2 mm. are worn off, but pits 2 and 4 run to the base of the crown. The various genera of the Toxodontia in the Deseado I would divide into four families as follows: Rhynchippidae: molars brachydont, secondary cristae lacking or little developed, none of the incisors caniniform, limbs slender, feet digitigrade, digits 3-3. Leontinidae: molars brachydont, secondary cristae lacking or little developed, upper inc. 2 and lower inc. 3 developed into caniniform teeth, limbs heavy, feet digiti- grade, digits 3-3 (according to Gaudry). Isotemnidae: molars brachydont, secondary cristae more or less developed, crowns contracted at the top, con- gulum more or less developed into a platform, skeleton unknown. Nesodontidae: molars hypsodont, secondary cristae highly developed, upper inc. 2 and lower inc. 3 caniniform, limbs heavy, feet digitigrade, digits 3-3. TOXODONT CLASSIFICATION 89 Rhynchippidae This family name is used for the three genera Rhyn- chippus, Morphippus, and Eurygeniops, which made up a part of Ameghino’s family, Notohippidae. ‘These forms I find much simpler than Coresodon, Interhippus, Stilhippus, and Nesohippus, which, by their molars, should be asso- ciated with Nesodontidae, unless it should prove that they did not have the incisors enlarged to caniniform teeth, in which case another disposition will have to be made of them. Ameghino places the Rhynchippidae among his Hippoidea, leading to horses, but we found a nearly com- plete skeleton of Rhynchippus equinus which in all particu- lars is typically toxodont. In the Deseado we found fourteen specimens belonging to this family, and strangely enough they were all Rhynchippus, and all of the species R. equinus. This family is distinguished by the brachydont, or nearly brachydont, molar teeth, being relatively simple, and the secondary cristae not being developed. The large basin in the upper premolars and molars is, therefore, not subdivided, but is deep, and rather narrow, usually ap- pearing as an oblique pit in the centre of the crown. There is no enlargement of the incisors to make caniniform teeth. Both the upper incisors and the canine have in the crown a longitudinal groove, which on wear becomes a pit, and being shallow may disappear entirely. The lower teeth are those typical of all toxodonts. The feet are tridactyl, and compact. The following three genera may be distinguished: RHYNCHIPPUS MoORPHIPPUS EURYGENIOPS ST AGS Sears 31 43 Formula Se as Oe Si ATS x LAS 3143 Skull moderately long muzzle short muzzle, with short heavy muzzle, slight constriction be- | with marked constric- hind canines tion behind canines Upper incisors groove or pit groove or pit groove or pit rele) THE DESEADO FORMATION OF PATAGNOIA RHYNCHIPPUS MorPHIPPUS EURYGENIOPS Lower incisors’ cingulum on the inner no cingulum _no cingulum face Upper premolars cingulum on ant. int. cingulum on ant. int. cingulum on ant. int. corner corner corner Upper molars basin deep basin shallow basin deep, with incipi- ent secondary bays Lower molars 4 bays bays 1 and 2 only bays T and 2 only Rhynchippus Ameghino Rhynchippus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 462. The teeth of both jaws are rooted, but tend to be hypso- dont. ‘The elongated incisors of the upper series are char- acterized by the presence of a longitudinal furrow in the top of each tooth, which, with wear, becomes a pit, and, as it is shallow, disappears in old individuals. This is the only suggestion of a horse character in the genus, but the pit in a horse’s incisor is a late development, and here it is also probably a specialization due to eating grass. Incisor I is the largest and they decrease in size toward either side. The canine is small, and is also marked by having a furrow in the crown, but in this case it is transverse to the long axis of the jaw. The premolars are peculiar in having on the anterior internal corner a highly developed cingulum, which so builds out the tooth that it is usually wide and is rectangu- lar in outline. As this cingulum rises, it incloses a bay on the ant. int. corner of the tooth, which, with wear, becomes first a bay, then a pit, and lastly may disappear entirely in old age. On each premolar the anterior and posterior lobes are developed, inclosing between them an elongated basin, which with wear becomes a long narrow pit. On the molars, the cingulum on the ant. int. corner is wanting entirely. The external anterior corner of the tooth, how- ever, is prolonged, so that the crown has a rhomboidal out- line. ‘The crown is made up in the typical manner of the wall, the anterior, and the posterior lobes, which inclose RHYNCHIPPUS oI between them an elongated basin, which, as in the pre- molars, becomes, on wear, a pit extending obliquely across the tooth. The lower incisors have no furrows in the crowns, but in this genus there is a small cingulum on the inner side just above the base of the enamel. The lower canine is incisiform, and also has the basal cingulum. Each of the premolars has, on the external side, a median vertical groove, beginning at the base of the enamel, and widening toward the top. This is progressive if less marked from pm. 1 to pm. 4. The premolars and molars consist essen- tially of two crescents, the shorter anterior, and the pos- terior which is about twice as long as the anterior. The details are as described on page 96, and seen in figure 55. The skull is of moderate height, nearly flat on top with wide zygomatic arches. The sagittal crest is moderately high, and slightly convex in the antero-posterior direction. The occipital region is overhanging and topped by short lambdoidal crests, which, extending to either side, unite with the zygomatic arches. The nasals are large, roughly rectangular, and slightly constricted just in front of the middle. The frontals are short, and project over the orbits in strong processes. The maxilla is large, bounding the front of the orbit, and extending backward in a strong zygomatic process which makes nearly half of the arch. The jugal, while stout, is short, and reaches from the long zygomatic process of the maxilla to the short one of the squamosum. The lachrymal bone is tiny, with a low tu- bercle, just below which is situated the lachrymal duct, just on the margin of the orbit. Just behind the zygomatic arch, the squamosum is inflated and contains a large hol- low chamber, as is typical among toxodonts. The mastoid bullae, while relatively small, are swollen into a globular form, and have a large hollow chamber. ‘The palate ex- tends back to just behind the last molar, a feature distin- guishing this genus from Morphippus. Q2 THE DESEADO FORMATION OF PATAGONIA Of the vertebral column, twenty-six vertebra are pre- served (a few being represented by neural arches only). The atlas and axis are unknown. Five cervicals are pres- ~ent, each with a short, slightly opisthocoelus centrum, and with low weak spines. The foramena for the vertebra artery are usually large. Cervical 3 has a rather slender trans- verse process, projecting down—and backward. On cer- vicals 4, 5 and 6, these lateral processes are enlarged into broad lamellae, which reach their maximum of size on the sixth. Cervical 7 has no lamella, simply a slender trans- verse process. These transverse processes are strikingly like those of Nesodon. The thoracic vertebrae (of which I have complete or in parts 15) have moderately high spines, which resemble those of Adinotherium, not only in the gen- eral build, but also in the presence of a foramen for the exit of spinal nerves through each neural arch. These foramena can not be referred to as adaptations, but are special features indicating close relationship with the Neso- dontidae. Six lumbar vertebra are present, each having broad depressed centra, and short wide spines. The rest of the column is unknown. The distal portion of the humerus is preserved, showing the trochlea to be relatively narrow, with a prominent internal phlange for the ulna. The epicondyles are both small. The supratrochlear fossa is moderately deep, the anconeal fossa very deep, a large perforation connecting the two. Of the ulna, only the distal end is preserved, and it is marked by a prominent styloid process, ending in the facet for the pyramidal, this facet continuing uninter- ruptedly into that for the pisiform. The two ends of the radius are preserved but its length can only be conjectured. The proximal end has a large facet for the humerus; the distal end two facets, for the scaphoid and luna respec- tively, the two being almost continuous, except as the outline of the shallow depressions is constricted near the middle. RHYNCHIPPUS 93 The carpus is preserved im toto and is decidedly weak for an animal of this size, though no more so than is the case of Nesodon and Adinotherium, with which forms the arrangement of the bones agrees in almost every detail. The scaphoid has a broad facet on the upper side for the radius, on the ulna side a narrow band-like facet for the luna, and distally facets for the trapezoid and the magnum, none for the trapezium. The luna is a larger bone with a broad radial facet on the upper side, a narrow facet for the scaphoid on the radial side, a larger one for the pyramidal on the ulnal side, and two broad facets for the magnum and unciform on the lower side. The pyramidal is a low, flattened bone, with a cup-like facet for the ulna on the upper surface, an elongated flat facet for the pisiform on the palmar surface, and below a broad facet occupying the entire lower side for the unciform. The pisiform is shaped like a tiny caleaneum, and, beside the facet for the pyra- midal, has a broad contact on the styliform process of the ulna. The trapezium is a flattened nodular bone, resting against the side of the upper end of Mc. II, for which it has a flattened contact surface, but it does not properly artic- ulate with any of the carpals. The trapezoid is a small bone, cuboidal in shape, with the proximal facet for the scaphoid rounded, and with a narrow facet for the sup- port of Mc. II on the distal end. The magnum is a larger bone, articulating proximally with the scaphoid and luna, on the ulnal side with the unciform and distally supporting Mc. III. The unciform is the largest of the carpal bones, articulates proximally on the luna and pyramidal, on the radial side with the magnum, and distally carries Mc. IV, while on the ulnal side there is a facet for the modular ves- tige of Mc. V. The metacarpals are longer than those of Adinotherium, and are much more closely pressed together, making a narrower, firmer foot. Three metacarpals are present (beside the modular vestige of Mc V.). Mc. Il and Mc. IV 94 THE DESEADO FORMATION OF PATAGONIA are slightly shorter than Mc. IIT, but not materially weaker, so that all three would reach the ground when the animal was standing. Though closely packed, the metacarpals are not grown together at any point. Distally each has a narrow trochlea, which carries a median crest on the palmar side only. Under the distal end of each metacarpal, there is a pair of small sesamoid bones. All the phalanges are very short and weak, with the articular surfaces cut under obliquely, suggesting that the toes are bent upward. Distally each toe ends in a slender cleft ungual phalanx, suggesting a claw-like hoof. Rhyn- chippus clearly walked in a semidigitigrade manner, the weight coming principally on the metapodials, the foot as a whole resembling that of a dog. The pelvis is unidentified. Though the bones are of about the same weight, the hind limb is longer than that of Adinothertum. The femur has a rounded head on a short but distinct neck, with the pit for the round ligament on the posterior margin of the head. The narrow digital fossa is deep. The greater trochanter is rugose and strong, but does not rise quite to the height of the head. The lesser trochanter makes a strong shelf-like process well below the head, while the third trochanter is a prominent process about the middle of the shaft, on the posterior side. The shaft is broad and flattened above, but narrows and becomes circular in section below. The condyles are rela- tively small, the inner being the smaller and more convex, while the outer is broader and less convex. The tibia and fibula are a little longer than the femur, fused proximally, free distally, as in toxodonts. The prox- imal end of the tibia is too weathered to permit detailed description. However the upper end is wide and flattened from front to back. Distally the bone narrows until the lower part of the shaft is circular in section, the distal end enlarging again in the neighborhood of the articulation. The fibula has a broad facet for the inner side of the astra- RHYNCHIPPUS 95 gulus, and on the distal end a flattened slightly concave facet for the calcaneum. The calcaneum is longer than in Nesodontidae. It is, however, heavy and stout, the tuber broadening slightly toward the free end, on the plantar side of which there is a tendinous sulcus as in Nesodon. The fibular facet is wide, rectangular, and convex. Of the astragular facets, the sustentacular extends well back onto the tuber, and the ectal is the usual ovoid surface. Distally there is a broad slightly concave facet for the cuboid, and external to this a narrow surface for contact on the navicular. Except in length, this bone is very like that of Adinotherium. The astragulus and rest of the tarsal bones are wanting. Parts of the metatarsals and a phalanx indicate that the hind foot is of the same tridactyl type as the front, differing only in that the median digit seems to be relatively a little heavier. Ameghino described three species of Rhynchippus, R. equinus, R. pumulis, and R. medianus. Rhynchippus equinus Ameghino R. equinus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 463. This species is the dominant one in the Deseado from the Chico del Chubut, west of Puerto Pisser, no less than fourteen individuals being represented in our collection, three by skulls, and one by the major part of a skeleton which was found associated with the skull of Leontinia, but was determined as belonging to this species, by the duplication of the radius with a specimen having the radius and lower jaws associated. The description of the generic characters is largely based on this skeleton. The three species are differentiated largely by their size, R. equinus being the largest, but as compared with R. pumulis it is not only larger but much heavier built. The skull has been described under the generic discus- sion. In young individuals, the furrow in the incisors and 96 THE DESEADO FORMATION OF PATAGONIA canine is marked as a groove, later as a pit, and still later is lacking altogether, as is the case in the specimen figured, for all three of my more complete specimens are old indi- viduals, as is also Ameghino’s type. All the incisors show Fig. 53. Dorsal view of skull—1/2 natural size. the cingulum near the base of the enamel. On account of the development of the cingulum on the inner anterior cor- ner of the premolars, these teeth are broadened out and overhang the palate in a marked degree, and are also much wider than long. Molar I is intermediate in character RHYNCHIPPUS EQUINUS 97 between the premolars and the succeeding molars, being only slightly rhomboidal in outline, while in the last two molars the anterior external corner is markedly prolonged. In different individuals, the lower jaw varies greatly in height, but this seems to me to be individual and sex varia- tion. The three incisors and the canine are subequal in Fig. 55. Right lower dentition of R. equi- nus; A, of a young in- - dividual; B, of an old Fig. 54. Left upper dentition, individual—r/2 natu- old individual—t1/2 natural size. ral size. size, closely crowded, and each with a small cingulum near the base of the enamel. MEASUREMENTS OF SKULL, SPECIMEN 3191 Skull, length from front of nasal to back of lambdoidal crest 21 mm. Skull, width across zygomatic arches [725mm Skull, width across postorbital processes 78 mm. Skull, height above molar 2 84 mm. Dentition, from upper inc. I to molar 3 140 mm. Dentition, from lower inc. I to molar 3 136 mm. Mandible, height under molar 2 35 mm. Mandible, height under the articulation 118 mm, U 98 THE DESEADO FORMATION OF PATAGONIA The atlas and axis are wanting, and the characteristics of the other cervicals have been given under the generic description. MEASUREMENTS, SPECIMEN NO, 3291. Cervical 3, length of centrum 18 mm. Cervical 5, length of centrum 18 mm. Cervical 6, length of centrum 21 mm. Cervical 6, height from base of centrum to top of spine 74 mm. Cervical 7, length of centrum 21 mm. Cervical 7, height from base of centrum to top of spine 55 mm. The first three or four of the thoracic vertebrae are rep- resented only by their neural arches and spines. ‘There wh ere = Sas ae Fig. 56. Cervicals, 5, 6 and 7—1/2 natural Fig. 57. Dorsal 6 and 7—1/2 nat- size. ural size. were at least fifteen in the series, for | have that number represented, but more probably the number was sixteen as in the case in Adinotherium. ‘Typical vertebrae measure: SPECIMEN 3291 Thoracic 3, langth of centrum 21 mm. Thoracic 3, height from base of centrum to spine 56 mm. Thoracic 6, length of centrum 22 mm. Thoracic 6, height from base of centrum to spine 79 mm. Thoracic 14, length of centrum 26 mm. Thoracic 14, height from base of centrum to spine 65 mm. In my series, there are six lumbars, which is one more than is credited to Adinotherium, though in that genus the RHYNCHIPPUS EQUINUS 99 number has not been definitely fixed. Typical lumbars measure as follows: Lumbar 2, length of centrum 29 mm. Lumbar 2, height from base of centrum to spine 65 mm. Lumbar 4, length of centrum 3r mm, Lumbar 4, height from base of centrum to spine 57 mm. There is nothing to represent the sacrum or caudals. Only the lower half of the humerus is preserved and that with specimen 3191, and it measures: Humerus, diameter of shaft 22 mm. Humerus, greatest width of distal end 46 mm. Humerus, width of trochlea 36 mm. Fig. 58. Humerus—1/2 Fig. 59. Right front foot—1/2 natural size. natural size. The distal ends of the radius and ulna are preserved in specimen 3291, as they were found in association with the carpus. ; Radius, diameter of the distal end 29 mm. Ulna, diameter just above styloid process 21 mm. Ulna, diameter of styloid process Il mm. The carpus is carefully drawn, from which the various measurements may be obtained. There is a tendency for 100 THE DESEADO FORMATION OF PATAGONIA the two rows of carpals to alternate, but this is not ad- vanced to any considerable degree. The trapezium is entirely isolated from the other carpals, and lies as a flat- tened scale, on the side of the upper end of Me. II. The metacarpals are closely crowded together, making a compact foot with very little freedom of motion in its upper part. The three carpals are of nearly equal length, though the third is slightly heavier and longer than the ’ es é Fig. 61. Pair of se- Fig. 60. Digit 4 of Rhynchippus from samoids under Mc. the side—1/2 natural size. I1V—1/2 natural size. others, but there is no tendency toward a further reduction of the toes. Metacarpus II, length 67 mm. Metacarpus III, length 74 mm. Metacarpus IV, length 69 mm. Under each metacarpel are two small sesamoid bones which lie either side of the low crest of the metacarpus. The toes are all short, with flattened articular ends, which are cut under in a very oblique manner. The second pha- lanx is much shorter than the others, while the distal, or ungual phalanx, is the longest and highest of the three. Each ungual phalanx is cleft by a deep narrow notch, much more suggestive of a claw than a hoof. The phalanges of all the toes are subequal in size, so that the measurements of the middle digit are given. First phalanx of digit III, length 12 mm. Second phalanx of digit III, length 8 mm. Third phalanx of digit III, length 16 mm. RHYNCHIPPUS EQUINUS IOI As preserved, the femur is crushed, and the distal end of the rotular trochlea is weathered off, but all the other characters are well preserved. The femur is slender, with : A Fig. 63. Right tibia - Fig. 62. Right femur posterior and fibula posterior side Fig. 64. Calcaneum— side—1/2 natural size. —1/2 natural size. 1/2 natural size, a small rounded head. The greater trochanter is heavy but does not project above the head, the lesser is small but well marked; and the third is usually far down the shaft. Of the two condyles the inner is the smaller and more convex. 102 THE DESEADO FORMATION OF PATAGONIA | SPECIMEN 3291 Femur, greatest length 202 mm. Femur, diameter of head 26 mm. Femur, width across head and greater trochanter 62 mm. Femur, width of internal condyle 16 mm. Femur, width of external condyle 24 mm. The tibia is much flattened at the upper end and tapers to nearly circular in section in the distal portion of the shaft. It is fused proximally to the fibula, but free distally. Tibia, length 222 mm. Tibia, greatest width proximally 51 mm. Tibia, least diameter of the shaft 24 mm, Tibia, diameter of distal articular end 23 mm. The fibula is a very slender bone, with the distal end swollen and heavy. As it rises from the carpus it is so twisted that it unites with the upper end of the tibia almost on the posterior surface. Fibula, diameter of the articular end 17 mm, Fibula, least diameter of the shaft 10 mm. The calcaneum is of moderate length, and very stout, resembling that of Adinotherium, except that it is longer. Calcaneum, length 64 mm. Calcaneum, width 28 mm. Of the hind foot there is preserved only the distal por- tions of two metatarsals, which are about the same size and character as those of the front foot, and a phalanx of the first row, also similar to the same one of the front foot. Figure 65 gives a restoration of the animal based on the bones described in the foregoing pages. The animal in all features turns out a typical toxodont, adapted, by the cropping teeth, and the broad-faced premolars and molars, for a grazing animal, but its advancement in adapting itself to feeding on grass has not proceeded very far, as is indicated by the shortness of the molars. The legs are longer than in the other families of the toxodonts which would signify that it had developed some speed, but the feet have progressed toward the modification of the hoofs 103 BRHYNCHIPPUS EQUINUS SS SESE 3 SS ts SS \ = p 4 eH 7 Wr 375 104 THE, DESEADO FORMATION OF PATAGONIA into claws, indicating a foot more like that of a dog, in which the weight is not carried on the ungual phalanges, but rather on the ball of the foot, or bases of the metapodials. I should not feel that this group was the ancestral one to later groups of toxodonts, but it seems rather to represent a line which terminates in the Deseado or very little later, not having run up into the Santa Cruz. The line of an- cestry for the toxodonts is rather through Leontinidae. Rhynchippus pumulis Ameghino R. pumulis Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 464. We found no speci- mens of this species, but Ameghino has described a complete skull, a fig- ure of which is repro- duced here. It indicates a smaller lighter built animal, differing from R. equinus not only in small size, but also in having a relatively longer andnar- rower head. ‘The indi- vidual is a rather old one, so that the pits in inc. I and 2 have disap- peared, as is also the case with the cingulum on the ant. int. corners of the premolars. Ame- os ghino gives the follow- Fig. 66. R. pumulis—1/2 natural size; A,topofskull; - . ° B, upper dentition, after Ameghino. Ing measurements 1n his description. Skull, length over all 155 mm. Upper dentition, from inc. I to m. 3 80 mm. MORPHIPPUS 105 Rhynchippus medianus Ameghino R. medianus Amegh., 1901, Bol. Acad. Nac. Cienc. Cordoba, t. 16, p. 375. This third species is intermediate in size between the two foregoing. No figure is given, but the following meas- urements give the size: Upper molar 2, length, 17 mm., width II mm. Length of lower molars 1 to 3 40 mm. Height of mandible under m. 2 24 mm. These figures would indicate a form about 15 [% larger / than R. pumulis, and 35 % smaller than R. equinus. Morphippus Ameghino Morphippus, Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 459. This genus is very similar to Rhynchippus, with the same dental formula, the same grooves in the upper incisors, and the same pattern of the premolars and molars. It differs, however, in the lower incisors having no cingulum at their base, in the upper molars having a shallower basin, and in bays 3 and 4 being absent from the lower molars. These features simply indicate a slightly less advanced specializa- tion, less hypsodont teeth. I do not think that the bays are any of them lacking in unworn teeth, but in a less hypso- dont tooth, with the pits extending a less distance into the crown, all indication of the bays disappears early. M. imbricatus is described as the type species, and four others have been described, all equal in size to M. imbrica- tus, and distinguished by the teeth being slightly more compressed, by the external cleft of the lower molars being deeper, or by variations in the pits. All these features I consider to be either age characters or individual variations, so that all five species of this genus are lumped under M. imbricatus. 106 THE DESEADO FORMATION OF PATAGONIA Morphippus imbricatus Ameghino M. imbricatus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 459. M. hypsolodus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 461. M. complicatus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 461. M. fraternus Amegh., 1901, Bol. Acad. Nac. Cienc. Cordoba, t. 16, p. 374. M. quadrilobus Amegh., 1901, Bol. Acad. Nac. Cienc. Cordoba, t. 16, p. 374. The general characters of this species are given under the generic description and I will here give only Ameghino’s measurements which go with the figure: Skull, length over all 210 mm. Skull, length of the palate 120 mm. Upper dentition, length the inc. 1 to m. 3 120 mm. Diameter of the palate opposite inc. 3 37 mm. Diameter of the palate opposite m. 3 75 mm. Height of mandible under m. 1 33 mm. Fig. 67. M. imbricatus—1/2 natural Fig. 68. E. latirostris, palatal view, after a pho- size; A, upper dentition; 6, lower den- tograph of the type—1/2 natural size; the cross tition after Ameghino. hatched area represents matrix not yet removed. EURYGENIOPS [07 Eurygeniops Ameghino Eurygenium Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 655. Eurygeniops Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 464. The name first given this genus was found to be preoc- cupied, and therefore changed. It is a clear cut genus, differing from the others in the family in the expansion of the front of the muzzle, and by the heavy broad character of the skull. Eurygeniops latirostris Ameghino E. latirostris Amegh., loc. cited above. This is the type species and is based on a muzzle which has never been figured, but which I figure, the drawing being made from a photograph taken by Professor Scott and kindly furnished me. The characters of the species are those of the genus, with the following measurements for specific determination, quoted from Ameghino: Palate, length 130 mm. Palate, width between incisors 3 41 mm. Palate, width between premolars 2 33 mm. Palate, width between molars 3 56 mm. Upper dentition, length from pm. R. to m. 3 82 mm. Upper premolar 4, length Il mm. Upper premolar 4, width 19 mm. Eurygeniops normalis Ameghino E. normalis Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 466. This second species is described as being much smaller than the preceding, the length from pm. 4 to molar 3 being 65 mm. CHAPTER, VII LEONTINIDAE Tus family was established to include a group of large, heavily built ungulates, not unlike rhinoceroses in form, which have rooted teeth, the molars being similar to those of Rhinchippidae, 2. e., composed of a wall and an anterior and posterior lobes, but with the cristae either lacking or little developed; and with the second upper, and the third lower incisors developed into tush-like caniniform teeth. Two genera are especially abundant, Leontinia of the Des- eado beds, and Colpodon of the Colpodon beds, the former with the formula 374<, the latter with -({4., In many ways, the family suggests Nesodontidae, and undoubtedly belongs to that series, if not directly ancestral. The lower molars are distinctly of the same type as in all the other toxodonts, but show a tendency to become hyposodont. The following genera have been assigned by Ameghino to the family. Some of them are based on very scant mate- rial and I have ventured to suggest in each case what dis- position I have felt to be the proper one. Leontinia, the type genus, is described in detail on pages 109-115. Scaphops is based on a mandibular symphysis, which is wider than usual for Leontinia, and on a second upper incisor which is compressed. The species in the genus Leontinia show a marked degree of variability, and I can see in this only individual variability, so that I place Scap- hops under Leontinia and S. grypus, as a synonym of L. gaudryt. Steniogenium is based on a mandibular symphysis with roots only of the teeth. The incisors are proclivous and inc. 3 small. I consider this also as Leontinia, and the species S. sclerops as a synonym of L. oxyrhynea, which I think is the female of L. gaudryt. LEONTINIDAE 109 Ancylocoelus is a valid genus, differentiated by its dental 3043 formula +23, the loss of the upper canine and the lower canine and first premolar distinguishing it from either Leon- tinia or Colpodon. Rodiotherium is based on a mandibular symphysis which would indicate an animal with the same formula as the foregoing genus, differing only in that lower incisor 3 is large. This, to my mind, does not make a generic char- acter, and at most the species, R. armatum, can only be considered an independent species belonging to the genus Ancylocoelus. Loxocoelus is a very questionable genus, based simply on an upper molar, which ‘is similar to that of Homolo- dontotherium, but more squared.”’ I feel that in regard to this genus it should stand as unknown until more material is found. In our collection, over twenty skulls and jaws belonging to this family turned up, but all clearly belong to two types, the typical Leontinia gaudryi, and some others in which the caniniform teeth are not so well developed, which are either L. oxyrhynca or, as | believe, the females of L. gau- dryi. It is this uniformity of the material which leads me to doubt the validity of the considerable number of genera which Ameghino has established, for I found on sectioning the teeth that between the little worn crown and the much worn one there was a marked difference in the appearance of the infoldings and in the development of the pits. Leontinia Ameghino Leontinia Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 647. Leontinia Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 469. Scaphops Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 475. Steniogenium Amegh., 1895, Inst. Geog. Argen., t. 15, p. 654. Steniogenium Amegh., 1897, Inst. Geog. Argen., t. 18, p. 475. Colpodon Gaudry, in part, 1906, Anal. Palaeontologie, t. 1, p. 30. s*i+; type species L. gaudryt. Of all the animals in the Deseado, this is the most abundant. The formula is 110 THE DESEADO FORMATION OF PATAGONIA Using this species as a basis, the following are the charac- teristic features. The first upper incisor is a small crop- ping tooth, with a well-developed cingulum high up on the inner face, which, when the tooth is worn down to the proper level, unites with the main part of the crown and incloses for a short time a small pit. On the external face there is also a feeble cingulum near the base of the enamel. The second incisor is greatly enlarged into a caniniform tush. In the species L. oxyrhynca, this tooth is much smaller but as this reduction of the tushes is the only dif- ference, I consider these forms as the female. The third incisor is again small, and has a well-developed cingulum on both the front and inner faces. The canine is similar to inc. 3. The first premolar is much reduced in size, with a weak cingulum on the outer face, and probably another on the inner side (the tooth is too much worn in my specimen to be sure). Beginning with premolar 2, the upper teeth are molariform. The premolars are rectangular in outline, each being much wider than long, and each having a cingu- lum on the outer side. On the inner side, along the anterior half of each premolar, there is a high cingulum, which, though interrupted at the anterior corner, continues around onto the anterior face of the tooth. On a worn tooth this anterior cingulum unites with the grinding surface, and leaves a small pit in the anterior internal corner, which is very suggestive of Rhynchippidae. In the middle of the grinding surface, there is an oblique pit, the remains of the basin in young teeth. The molars continue to increase in size toward the rear. They have a vestige of a cingulum on the external side, no cingulum on the inner side, but on the anterior side for about one third the distance there is a cingulum similar to that on the premolars. In the middle of the grinding surface is an elongated oblique pit, similar to that in the premolars, but a little more advanced, there being a trace of the development of cristae. LEONTINIA 1 Ot In the lower dentition, the first two incisors are small cropping teeth, with the anterior face flattened and having a trace of a cingulum; while on the inner face the cingulum is well developed. Incisor 3 is developed into a tush cor- responding to inc. 2 in the upper dentition. As in the upper teeth, there are two types, that of L. oxyrhynca with the tush only about twice the size of an incisor, and that of L. gaudryt with it much larger. All the premolars are molariform and of the typical tox- odont character, consisting of two crescents with a pillar and septum in the posterior crescent. The septum, how- ever, does not appear until on pm. 3 and on all succeeding teeth, and is usually indicated by a tiny pit. From the front to the back, the premolars are progressively larger, each having a cingulum on both the internal and external faces. The molars continue to increase in size progres- sively, and have the same characters as the premolars, except that the crescents are more elongated, and the cin- gula are gradually becoming smaller toward the rear. The skull is low and heavy, with a low sagital crest, and with the lambdoidal crests continuous with the upper mar- gin of the zygomatic arches. The nasal bones are short and wide, and are markedly raised above the nasal cham- ber. On the outer margin of each is a low boss, somewhat as on the nasals of the rhinoceros, Dicerathertum, which would indicate that this form had a small pair of nasal horns.* The frontal bones are broad, projecting laterally in strong postorbital processes, which, with those from the jugals, almost close the orbit behind. The premaxillae are pecu- liar in having a median crest on the upper surface, the top of the crest being rugose, as though in life it had continued upward as a cartilage septum. The maxillae rise well up * Scott has restored the head of Leontinia gaudryi with a single median horn, but no specimen in my collection would indicate anything but a pair of nasal horns. See Scott, Mammals of the Western Hemisphere, fig. 138, 1912. iz THE DESEADO FORMATION OF PATAGONIA on the sides of the skull, bounding the lower part of the orbit, and having a short zygomatic process. The small lachrymal is but little exposed on the exterior surface of the skull, the lachrymal pit being well inside the orbit. The zygomatic arches are broad and heavy, and composed mostly of the wide jugal bones. The palate is highly arched and relatively narrow, the crowns of the premolars and molars projecting inward over it, thus narrowing it still more. It extends back well beyond the last molar. The large tympanic bullae are hollow, and the cavity in the squamosum seems to be reduced in size, as compared with Rhynchippidae or Nesodontidae. The occipital condyles are set well apart and are sessile; and the paroccipital proc- esses are long and slender. The atlas, axis and cervical 3 are associated with the skulls. The atlas is short, heavy, and has the anterior cotyles broad, deeply excavated and wide apart; while the posterior cotyles are nearly flat, and high as well as wide. The transverse processes are only moderately wide, but are very heavy, especially along the posterior margin. The centrum of the axis is flattened, the neural canal, wider than high, and the neural spine of moderate height. The anterior cotyles are broad and moderately convex, and the odontoid process is a stout peg-like process, somewhat higher than wide. Slender transverse processes project sharply from the centrum, and have at their bases a large canal for the vertebral artery. Cervical 3 is shorter than the axis, has a less depressed centrum, a small neural spine, and short wide transverse processes. Though I have skulls and jaws to represent some twenty- five individuals, no limb material was found in direct asso- ciation with any of them. However we did find a humerus, radius and ulna on the same level and about fifteen feet from one of the skulls, and as it corresponds in size, and as humeri of this type are the most abundant skeletal bones found (as is also the case with the skulls), I have considered LEONTINIA 113 it proper to associate these fore limb bones with these skulls. The humerus is a stout bone, of medium length, with a large sessile, and but little rounded head. The external tuberosity is wide, thick and projects a little above the head, while the internal tuberosity is so small as to be almost negligible. The shaft is flattened laterally at the upper end, but distally is compressed in the antero-pos- terior direction. The supratrochlear fossa is shallow, the anconeal deep, but there is no foramen connecting them. The external condyle is small, the internal much larger. The trochlea is narrow, with a swollen articular area for the radius, and a wider saddle-like one for the ulna. The ulna is a stout, nearly straight bone, slightly longer than the humerus. The olecranon process, though large, is not excessive. The sigmoid notch makes a deep semicircular cavity, with the articular facets expanding on either side. It was closely fitted to the radius so as to allow little or no rotary motion of the forearm. The facet for the radius is a narrow band-like area just below the sigmoid notch. The shaft is almost rectangular in section. Distally the ulna contracts sharply into a heavy styloid process, on the end of which is a large convex facet for the pyramidal, which merges without interruption into the facet for the pisiform. The radius is a slenderer bone, with a relatively small prox- imal head, but distally expanded into a much larger articu- lar end. My specimen is considerably weathered, but shows a wide shallow articular facet for the humerus, and a band-like facet for the ulna, but otherwise it gives little more than the length. Of the hind limb, Gaudry* figures the astragulus and the calcaneum, the former short and with a low trochlea, the latter also short and with a broad facet for the fibula. Gaudry also states that the foot was tridactyle and planti- grade, but I am doubtful of the plantigrade feature. * Anales Palaeontologie, 1906, t. I, p. 28. 8 114 THE DESEADO FORMATION OF PATAGONIA Ameghino has made six species of this genus, L. gaudryz, L. fissicola, L. lapidosa, L. oxyrhynca, L. stenognatha, and L. garzoni. All of the first five are described as of the same size as L. gaudryi. L. garzoni is a smaller, about 60 per cent. of the size of the others. Of the first five listed, the first three have the large incisor and I consider them all L. gaudryi. L. oxyrhynca and L. stenognatha are described as having small canines and I believe that this is a sexual difference only, so have considered these two species as also belonging to L. gaudryi, but females. I have made a careful comparison of L. gaudryi and L. oxyrhynca and find them identical in all the features except in the region of the canines where the latter is weaker, and can see no more than sexual differences. Usually with this weakness of the canine goes a smaller or lighter build of the lower jaw which is what would be expected. The points by which the various species were differentiated were, beside the size of the canine, the presence or absence of pit 3, and the vari- ation in the foldings on the outer sides of the lower molars, which I find on sectioning a tooth appear deeper or shal- lower according to whether the tooth was more or less worn. Leontinia gaudryi Ameghino L. gaudryi Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 648. L. gaudryi Amegh., 1897, Bol. Geog. Argen., t. 18, p. 472. Scaphops grypus Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 629. Scaphops grypus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 475. Steniogenium sclerops Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 654. Steniogenium sclerops Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 475. Leontinia fissicola Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 474. L. (Senodon) lapidosa Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 649. Females L. oxyrhynca Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 472. L. stenognatha Amegh., 1897, Bol. Inst. Geog. Argen., t. 15, p. 474. Colpodon gaudryi Gaudry, 1906, Anal. Palaeontologie, t. 1, p. 30. This species is represented in the Amherst Collection by five more or less complete skulls, and over twenty jaws, LEONTINIA GAUDRYI 115 being by far the commonest fossil of the Deseado beds on the Chico del Chubut River, west of Puerto Visser. As mentioned above, there are two types, the first, with larger i Saae 7. , Fig. 70. Lower Fig.71. Lower den- Fig. 69. Right upper dentition dentition of male tition of female—1r/2 —1/2 natural size. —1/2naturalsize. natural size. canines and heavier mandibles, designated by Ameghino as L. gaudryi, which I consider males; second, those with smaller canines, and lighter mandibles, slightly smaller in size, which Ameghino designated L. oxyrhynca and I con- 116 THE DESEADO FORMATION OF PATAGONIA sider females. Practically all of the other species are based on mandibular symphyses varying in details from the above, but in no case sufficiently for me to see a specific variation. The general features have been discussed under the generic description. Incisor 1 has a long crown and a long root, and is greatly crowded by the tushes. Incisor 3 and pm. I have the same crowded appearance. In giving the measurements I have used a skull which is typically L. gaudryt, a male, and parallel to it have put another skull, which is typically L. oxyrhynca, the female. By compar- ing the two sets of figures, the shortening, of which Ame- ghino speaks, will be seen to be all in the region of the tushes. SPECIMEN 3290 SPECIMEN 3291X MALE FEMALE Upper dentition, length from inc. 1 to m. 3 227 mm. Upper dentition, length from pm. 1 to m. 3 180 mm. Incisor 1, length I2 mm. Incisor 2, length 25 mm. Incisor 3, length Il mm. Canine, length I2 mm. Premolar 1, length 12 mm. Premolar, 1 width 18 mm. Premolar 2, length 18 mm. Premolar 2, width 28 mm. Premolar 3, length 20 mm. Premolar 3, width 34 mm. Premolar, 4, length 22 mm. 20 mm. Premolar 4, width 38 mm. 34 mm. Molar 1, length 28 mm. 24 mm. Molar 1, width 4o mm. 38 mm. Molar 2, length 36 mm. 33 mm, Molar 2, width 48 mm. 45 mm. Molar 3, length 46 mm. 46 mm. Molar 3, width 48 mm. 47 mm. Lower dentition, height of mandible underm.1 66 mm. 56 mm. Incisor 1, length 8 mm. 8 mm, Incisor 2, length 10 mm. 10 mm. Incisor 3, length 23 mm. 13 mm. Canine, length : 8 mm. g mm, Premolar 1, length 13 mm. 8 mm LEONTINIA GAUDRYI EL7, SPECIMEN 3290 SPECIMEN 3291x MALE FEMALE Premolar 1, width I2 mm. I2 mm. Premolar 2, length 18 mm. 16 mm, Premolar 2, width 17 mm. 15 mm. Premolar 3, length 2I mm. 18 mm. Premolar 3, width 19 mm. 16 mm. Premolar 4, length 24 mm. 21 mm. Premolar 4, width 19 mm. 18 mm. Molar, 1, length 33 mm. 27 mm. Molar 1, width 20 mm. 20 mm. Molar 2, length 40 mm. 37 mm. Molar 2, width 20 mm. 20 mm. Molar 3, length 57 mm. 57 mm. Molar 3, width 20 mm, 20 mm. So pe saree ws Fig. 72. Top view of skull of L. gandryi (female)—1/4 natural size. In the skulls there is considerable variation in size in the different individuals, but the proportions remain very 118 THE DESEADO FORMATION OF PATAGONIA much the same throughout. are from 5 to 10 per cent. smaller throughout. In the female the snout is relatively a little shorter, and in general the female skulls The fol- Fig. 73. L. gandryi, view of case of the skull, female (L. oxyhynea)—1r/4 natural size; Tym- pamic bullae broken open. lowing two sets of figures illustrate the comparative sizes of the two sexes. Skull, greatest length front to back Skull, greatest width Skull, length of nasal bone Skull, length of palate SPECIMEN 3335 SPECIMEN 3291X FEMALE MALE 420 mm. 252 mm. 115 mm. 235 mm. 392 236 102 230 mm. mm. mm. mm. LEONTINIA GAUDRYI I19 The atlas associated with skull No. 3335 is a decidedly heavy bone in all its proportions. The axis and the third cervical were associated with skull No. 3291x, and are likewise heavy bones. The following are typical meas- urements: Atlas, greatest length 86 mm, Atlas, greatest width 170 mm, Axis, length of centrum and odontoid process 132 mm, Axis, length of odontoid process 34 mm, Axis, width across anterior cotyles 98 mm. Cervical 3, length of centrum 66 mm. Cervical 3, width of posterior end of centrum 55 mm, Fig. 74. Atlas seen from below—1/4 natural Fig. 75. Axis and cervical vertebra, No. 3—1/4 size. natural size. While there are other vertebrae in the collection, which probably belong to this species, I have not cared to make the association without some evidence of a definite char- acter. However, in the case of a fore limb, which was found fairly near one of the skulls, is of proper size, and because this humerus occurs with something like the fre- quency of the skulls, I have been convinced that it belonged to this species, and so described it under the genus. This specimen consists of the two humeri, the radius and the ulna, No. 3328. Humerus, greatest length 314 mm. Humerus, diameter of head 77 mim, Humerus, transverse diameter of the shaft 43 mm. Humerus, width of distal end 116 mm. The ulna lacks some 60 mm. in the middle of the shaft, but when fitted to the radius its length can readily be ob- 120 THE DESEADO FORMATION OF PATAGONIA tained. The radius is considerably weathered so that measurements of the distal end are only approximate. Ulna, length over all 430 mm. Ulna, transverse diameter of distal end 58 mm. Radius, length over all 310 mm. Fig. 78. Proxi- mal end of right radius—1/4 natural size. Fig. 76. Right humerus from the posterior side—1/4 natural size. Fig. 77. Right ulna from exter- nal side—1/4 natural size. ANCYLOCOELUS I2I Leontinia garzoni Ameghino L. garzoni, Amegh., 1896, Bol. Inst. Geog. Argen., t. 15, p. 650. L. garzoni, Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 474. We were not fortunate enough to find this species, but as described by Ameghino it is about 60 per cent. of the size of L. gaudryi. The type is a lower jaw, for which the following figures are given: Lower dentition, length from pm. 1 to m. 3 120 mm. Lower dentition, length from pm. 1 to pm. 4 45 mm. Lower dentition, length of pm. 4 15 mm. Lower dentition, length of m. 3 39 mm. Ancylocoelus Ameghino Ancylocoelus Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 652. Ancylocoelus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 475. Rodiotherium Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 653. Rodiotherium Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 476. . . ci £0 . . ° 3043 This genus differs from Leontinia in its formula, $345 but, except for the loss of these canines and the lower pre- molars, is very similar. In this it seems to approach the line which gave rise to Colopdon. The premolars and molars are also narrower in proportion than in Leontinia. | have placed Rodiotherium also under this genus as I can not see a generic difference in the descriptions. However we were not fortunate enough to find these forms. Ameg- hino has described four species as follows: A. frequens, 1895, Bol. Inst. Geog. Argen., t. 15, p. 475. Upper dentition, pm. 1 to m. 3 150 mm, Lower dentition, pm. 2 to m. 3 150 mm. Upper molar 3, length 39 mm. A. lentus, 1901, Bol. Acad. Nac. Cordoba, t. 16, p. 407. Upper molar 3, length 48 mm. A. minor, 1901, loc. cit. Upper molar 3 34 mm. A. (Rodiotherium) armatum, see cit. above. Based onan imperfect mandibular symphysis, in which incisor 3 is very large. CHAPTER, Vit NESODONTIDAE Tuts family is characterized by the teeth being hyp- sodont, the second upper incisor and the third lower in- cisor being enlarged into caniniform teeth, the upper molars complicated by the development of cristae, limbs short, feet tridactyl and semidigitigrade. Fig. 70. A, upper and a lower molars 2 of Proadinotherium; £6, upper and 6 lower molars 2 of Coresodon; C upper and ¢ lower molars 2 of Neudon—1/2 natural size. In the Santa Cruz, the family is represented by the two genera Nesodon and Adinotherium. in the Deseado we find Proadinotherium evidently ancestral to Adinotherium and very little differentiated from it. Ameghino has de- scribed a genus, Pronesodon, which is evidently ancestral to Nesodon. 1 have referred Coresodon to this family be- cause the molars of the upper and lower jaws are very close to those of Adinotherium. Ameghino has also de- scribed two genera, Nesohippus and Interhippus, based on upper molars which are very similar in pattern to Adi- notherium and which I believe belong to this family, if they prove to be valid genera, of which I have some doubt, feeling that they will prove to be the deciduous upper pre- PROADINOTHERIUM 128 molars of Proadinotherium or some similar form. The genus Senodon, which Ameghino also places in this family, I feel will prove to be worn teeth of Leontinia. Proadinotherium Ameghino Proadinotherium Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 625. The dental formula is {743, as in Adinotherium, the chief difference being that the teeth are less hypsodont Fig. 80. P.leptognathus, rear portion of skull—1/2 natural size; shaded areas are matrix. than in the Santa Cruz genus. Little is known as yet of the skeleton, but when more is known probably more dis- tinctive characters will appear. Ameghino made two species, P. leptognathus which we also found, and P. angus- tidens a much smaller form, 124 THE DESEADO FORMATION OF PATAGONIA Proadinotherium leptognathus Ameghino P. leptognathus Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 625. P. leptognathus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 467. Of this species we found on the Chico del Chubut River, west of Puerto Visser, three specimens; the back of a skull as far forward as molar 2, and two lower jaws. In general, the species is very similar, even to size, to Adinotherium ovinum of the Santa Cruz. The upper molars are strongly hypso- dont, curved teeth. On the upper surface, the basin is subdivided by two strong cristae into three smaller bays. In an early stage of wear, the second crista unites with the posterior lobe, convert- ing bay 3 into a pit. On the posterior margin of the tooth, the cingulum is de- veloped so as to appear like a third crista, ig. 81. Left lower je a: ' withtineisor sand us” which inclosed bay 4, and when the tooth ccammen is worn, bay 4 becomes a pit also. In my lower jaw incisor 3 is developed into a strong caniniform tush. Most of the teeth are lacking, but lower molar 2 is a strongly compressed, hypsodont tooth, surrounded by a thick layer of enamel. This tooth rises 22 mm. above the well-developed roots, and is already considerably worn down. ‘The pillar is prominent as a strong fold in the middle of the posterior crescent. In this specimen there is no trace of the usual pit (3) indi- cative of the septum, but I should expect to find it in a younger specimen. ‘The mandible broadens in front into a scoop-like anterior end, and the alveoli of the first two in- cisors would indicate that they were proclivous. The alve- oli for the other teeth are aranged as in Adinotherium. PRONESODON 125 MEASUREMENTS Skull, width across the zygomatic arches 148 mm. Skull, width across opposite m. 3 (outside) 73 mm. Upper dentition, molar 2, length 25 mm., width 13 mm, Upper dentition, molar 3, length 23 mm., width 12 mm. Lower dentition, incisor 3, length 13 mm., width 7 mm, Lower dentition, molar 2, length 20 mm., width fey seibin Proadinotherium angustidens Ameghino P. angustidens Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 467. This is based on a single lower tooth, which is considered either pm. 4 or m. I, and measures 13 mm. long by 45 mm. wide. Pronesodon Ameghino Pronesodon Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 626. The genus is said to resemble Proadinotherium, but with the caniniform incisors proportionally much shorter. An associated calcaneum is shorter than that of Adinothertum and longer than that of Nesodon. Two species are described. Pronesodon cristatus Ameghino P. cristatus Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 626. P. cristatus Amegh., 1897, Bol. Inst. Geog. Argen., t. 15, p. 467. This species is very imperfectly known, is characterized by a large external anterior style, molars said to be 15 mm. wide. Pronesodon robustum Ameghino P. robustum Amegh., loc. cit. above. This is a larger species, of which the three lower molars are known, and which measure 16, 22, and 30 mm. in length respectively, while they are 9-10 mm. wide. 126 THE DESEADO FORMATION OF PATAGONIA Coresodon Ameghino Coresodon Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 630. Coresodon Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 459. Coresodon Gaudry in part, 1908, Anal. Palaeontologie, t. 1, p. 46. In this genus, the pattern of the upper molars is essen- tially the same as in Proadinotherium, and they are of the same hypsodont character, and with roots. I can now find only the fact that in Coresodon the teeth are more compressed and somewhat more hypsodont, as a feature by which to distinguish this genus from Proadinotherium. Gaudry figures the front of a lower jaw under the name Coresodon which lacks the caniniform incisors. I have doubted the association, but should it prove correct, then this genus would be markedly different in that respect. Two species have been described, C. scalpridens, and C. cancellatus, both of which I consider the same. Coresodon scalpridens Ameghino C. scalpridens Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 630. C. scalpridens Amegh., 1897, Bol. Inst., Geog. Argen., t. 18, p. 459. C. cancellatus Amegh., 1901, Bol. Acad. Nac. Cienc. Cordoba, t. 16, p. 374. Of this species we found two specimens, one containing the three lower molars, the other the second lower molar 3 seat il SS) hes) CS A B 6; D Fig. 82. Sections of second lower molar; A, top; B, 4mm. down; C, 10 mm. down; D, 18 mm. down—natural size. only. In establishing C. cancellatus, Ameghino says it is of the same size as C. scalpridens, but distinguished by the basin in the upper molars being narrower, the internal fold not being bifurcated, and by the absence of islets of CORESODON 127 enamel. All these features seem to me to be the results of wear. While the pattern of the upper molars is the same as in Proadinotherium, these teeth are about as wide as they are long. The lower molars, however, are more com- pressed, with the ante- rior crescent occupying about a third of the tooth, and having in the early stages a deep pit, which disappears when the tooth is worn down. In the middle of the basin of the posterior crescent is a large pillar, and between this and the median horn of the crescent is a tiny septum, which early unites with the pillar, leaving a tiny pit (3) which soon disappears entirely. In fact, in an old tooth, the second and fourth bays, having become pits, may even be lost also. Fig. 83. Molars 1 to 3—natural size MEASUREMENTS Upper dentition, molar 1, length 19 mm. @ Ameghino. Upper dentition, molar 1, width 12 mm. @ Ameghino. Upper dentition, m. I to m. 3, length 52 mm. @ Ameghino. Lower dentition, premolar 2, length 13 mm. @ Ameghino. Lower dentition, premolar 3, length 13 mm. @ Ameghino. Lower dentition, premolar 4, length 17 mm. @ Ameghino. Lower dentition, molar 1, length 18 mm., width 7 mm. Lower dentition, molar 2, length 19 mm., width 7 mm. Lower dentition, molar 3, length 20 mm., width 7 mm. Interhippus Ameghino Interhippus Amegh., 1904, Anal. Mus. Nac. Buenos Aires, ser. 3, t. 3, p. 183. Interhippus Amegh., 1904, Anal. Soc. Cienc. Argen., t. 56, p. 34 of reprint. This genus was established on isolated teeth which closely resemble those of this family, though the genus was placed among the Rhynchippidae by Ameghino. The teeth de- scribed as molars are much elongated and have the cristae greatly developed, and in one species there is a style rising about the middle of the inner side of the molar. Another feature emphasized as characteristic of this and the next 128 THE DESEADO FORMATION OF PATAGONIA genus is, that the crowns are expanded much wider than the roots. While there is not yet enough direct evidence to prove it, I feel that this and the next genus will prove to be deciduous teeth, of either Proadinotherium or some related genus. Two species of this genus have been de- scribed, both from the upper Deseado. 4 I. phorcus Amegh., loc. cit. above. This species is characterized by its size, the last upper molar (so called) measuring 16 mm. long by 14 mm. wide. I. deflexus Amegh., 1904, Anal. Mus. Nac. B. A., ser. 3, 3, Ds 83: This species is based on a worn tooth designated as molar 1 (probably d. pm. 3) 14 mm. long by 19 mm. wide. Sse Fig. 84. I. phorcus. Fig. 85. I. deflexus, Fig. 86. N. insulatus, “Upper molar 3’’—natural “Upper molar 1”’—natural “Upper molar 1’’—natural size, after Ameghino. size, after Ameghino. size, after Ameghino. Nesohippus Ameghino Nesohippus Amegh., rg04, Anal. Soc. Cienc. Argen., t. 56, p. 34 of reprint. Nesohippus Amegh., rgo4, Anal. Mus. Nac. B. A., ser. 3, t. 3, p. 218. This genus is described as very like the foregoing, but differs in having a strong perpendicular style on the ante- rior external face of the upper molars. As in the preced- ing genus, the crown is considerably expanded above the roots. I feel that this genus will also prove to be the milk teeth of some one of the genera of this family. One species is described, based on a single tooth. N. insulatus Amegh., 1904, loc. cit. under the genus. The species is just as described under the genus, the last upper molar measuring 24 mm. long by 16 mm. wide; given as from the upper Deseado. GHAPTER Ex [SOTEMNIDAE Tuts family is distinguished by the formula $743, by the incisors, canine and premolar t all being of subequal size, by all the teeth being brachydont, and by the cres- cents of the lower premolars and molars being modified. On these lower premolars and molars the anterior crescent is longer than the posterior, and the short posterior cres- cent on the exterior of the tooth; so that its anterior horn, instead of uniting with the posterior horn of the anterior crescent, comes in back to about the middle of the anterior crescent. Then the pillar, which in the other families is situated in the posterior crescent, is opposite the posterior horn of the posterior crescent. The small animals which represent this family are rare in the Deseado beds, much more abundant in the Casamayor. ‘The family seems to have died out in the Deseado as no forms are referred to it in later epochs. We found no specimens belonging to the family; but to make this discussion complete, I will give a digest of Ameghino’s descriptions, with reproductions of such figures as he has given. All of the genera and species are based on very fragmentary material. The genera assigned to the family are Trimerostephanos, Pleurocoelodon, Lophocoelus and Henricofilholia. Trimerostephanos Ameghino Trimerostephanos Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 646. Trimerostephanos*Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 483. This genus is based on upper and lower teeth, and dis- tinguished by the premolars and molars having a weak style on the anterior corner, and by the anterior lobe being considerably larger than the posterior. Four species have been described. 9 130 THE DESEADO FORMATION OF PATAGONIA T. scabrus Amegh., loc. cit for genus. This is the type species, originally based on the third lower molar, to which was later added, upper premolar 4 Fig. 87. T. scabrus—natural size; A, upper premolar 4; B, lower molars t and 2. and the molars, and lower molar 2. The following measure- ments are given: Upper premolar 4, length 15 mm., width 21 mm. Upper molar 2, length 30 mm: Upper molar 3, length 35 mm. Lower molar 2, length 20 mm. Lower molar 3, length 29 mm, T. scalaris Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 483, is based on lower pm. 2 to m. 2, a somewhat smaller species than the preceding, the series as given measuring 53 mm. Fig. 88. T.scalaris, premolar 2 to molar 2—natural size. T. angustus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, Dp? 4id4s This species is described without a figure, as smaller than 7. scalaris, pm. 2 to m. 2 being 59 mm. The mandible is also slenderer. PLEUROCOELODON 131 T. biconus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18. p. 484. This species is based on two lower premolars, said to be the same size as 7. angustus, but with the pillar larger. Pleurocoelodon Ameghino Pleurocoelodon, Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 645. Pleurocoelodon, Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 484. This genus is distinguished by the absence of the style on the anterior external margin of the upper molars, in- Fig. 89. P.wingei—natural size; A, first molar; B, third molar. stead of which the external face is excavated medianly. Two species are described, based on isolated upper teeth. P. wingei Ameghino P. wingei Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 645. P. wingei Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 485. This species is founded on a couple of isolated molars, probably belonging to the same individual. The following measurements are given: Upper molar 1, length 22 mm., width 26 mm. Upper molar 3, length 24 mm., width 29 mm. P. cingulatus Amegh., loc. cit. above, is based on an in- complete upper molar, probably the second, which is dis- tinguished by having the internal cingulum excessively developed. It measures 30 mm. in length. 132 THE DESEADO FORMATION OF PATAGONIA Lophocoelus Ameghino Lophocoelus Amegh., 1904, Anal. Soc. Cient., Rep. Argen., t. 58, p. 245. Lophocoelus Amegh., 1904, Anal. Mus. Nac., ser. 3, t. 3, p. 352. The genus is founded on a single upper third molar from Mazaredo, which is distinguished by a feeble style on the external face, by the anterior lobe being obliquely placed, and by the presence of a small secondary bay on the posterior side of the great internal basin. L. macrostomus Amegh., loc. cit. above. This species is the only one described, and has the generic features, the upper m. 3 being 21 mm. long, by 25 mm. wide. Henricofilholia Ameghino Henricofilholia Amegh., 1901, Bol. Acad. Nac. Cordoba, t. 16, p. 404. The type species is /7. cingulata, based on a single upper molar. In general the upper molars are similar to those of Leontinia, but more brachydont, and with the internal cingulum well developed and tending to be crenulated. Four species have been made, all based on isolated upper molars. Henricofilholia cingulata Ameghino H. (? Parastropotherium) cingulata Amegh., Bol. Inst. Geog. Argen. t. 15, p. 640. H. (? Parastropotherium) cingulata Amegh., 1897, Bien og mE scine latent uc per Bol. Inst. Geog. Argen. t. 18, p. 450. 7 molar 1—natural size, after H, cingulata Amegh., 1901, Bol. Acad. Nac. Cienc. Ameghino. “ Cordoba, t. 16, p. 404. This is based on an upper molar 1 of which I reproduce Ameghino’s figure. It measures 28 mm. long by 29 mm. wide. HENRICOFILHOLIA 133 H. lustrata Amegh., 1901, Bol. Acad. Cienc. Cordoba, t. 16, Dp: 405. This species is smaller than the preceding, and is based on an upper molar 1 and a last lower molar. The measure- ments are as follows: Upper molar 1, length 25 mm., width 25 mm, Lower molar 3, length 25 mm., width 12 mm, Fig. or. H, inaequilatera, upper molars 3 and 4—natural size, after Ameghino. H. inaequilatera Amegh. loc. cit. above. This species is larger than the preceding with the in- ternal cingulum more developed. Upper molar 2 measures 30 mm. long by 29 mm. wide. H. circumdata Amegh., loc. cit. above. This is a still larger type, with the internal cingulum enormously developed. Upper molar 1 measures 42 mm. long by 36 mm. wide. CHAPTER xX HOMALODONTOTHERIA Tue forms making up the Homalodontotheria are char- acterized by a dentition which is clearly a derivative of that of Toxodontia, but is distinguished by the teeth being brachydont, by the canines being the teeth which tend to become tush-like, though not advancing to a marked degree. But the distinctive feature of the suborder is found in the feet, which are clawed, the ungual phalanges being deeply cleft; and further, the animals seem to have walked on the sides of the foot, suggesting the Ancylopoda; but there does not seem to have been a phylogeretic re- lationship, rather it is a case of parallel development. Most of the forms found are of considerable size, and they are relatively scarce in all the formations. The representatives of the group in the Deseado all belong to the genus Asmodeus, which seems to be directly ancestral to the Santa Cruz genus FHomalodontotherium, which seems to be the last representative of the series, no specimens referable to the suborder having been found in later beds. Asmodeus Ameghino Asmodeus Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 643. Asmodeus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 476. The formula is $+4 4%, the upper incisors have pits in the crowns; the canines are moderately enlarged; the upper premolars and molars consist of an external wall, with an anterior and posterior lobe, the lower premolars and molars are typically like those of toxodonts. Two species have been distinguished, a larger, A. osborni, and a smaller, A. scotti. Our collection contains seven speci- mens, all of which should apparently be assigned to A. osbornt. ASMODEUS OSBORNI 135 Asmodeus osborni Ameghino A. osborni Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 644. A. osborni Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 478. Homalodontotherium osborni Gaudry, 1906, Anal. Palaeontologie, t. 1, p. 11. The type of this species is a calcaneum and astragulus, to which Ameghino later assigned the rear part of a mandi- ble with pm. 4 and the three molars; also a milk dentition, this last I think wrongly, for it is too small. I should interpret this specimen as deciduous inc. 2 to deciduous pm. 4, plus permanent molar 1, in which case the permanent molar corresponds to that of A. scott and it is not necessary to discuss ‘the remarkable bicuspid canine,’ as Ameghino Fig. 92. Molars 1-3 of the left side—1/2 natural size. does. Gaudry had some of this material, upper molars, the lower end of the humerus, the ulna, caleaneum and astragulus, and he referred the genus as the same as Homoladontotherium. \Vith this last, I can not agree. We found the three upper molars, the lower end of the humerus, part of the radius, the tibia, and two phalanges, all on the Chico del Chubut, west of Puerto Visser. While brachydont, the external faces of the molars are high, and each has a tiny cingulum along the base of the crown. There is also a strong cingulum around the anterior, internal, and posterior faces of the crown, which on the posterior margin flares out, making a marked and characteristic ridge. The grinding surface, with its ex- ternal wall and two transverse lobes, is very similar to the molar of a rhinoceros. When the tooth wears down, the 136 THE DESEADO FORMATION OF PATAGONIA inclosed basin becomes a large pit. Between the posterior Jobe and the flaring cingulum on the posterior margin, there is also a small posterior bay, which, in an old tooth, will also appear as a pit, but being shallow, it does not last long. The lower molars, as figured by Ameghino, are of the same type as those of the toxodonts, consisting of two cres- cents with the pillar in the middle of the posterior cres- cent, but the crescents and pillar are very plump; so that with wear they form broad grinding surfaces; and the bays, instead of becoming pits, first appear as notches, then disappear entirely. Each premolar and molar has a cingulum on the internal and external sides. Fig. 93. Premolar 4 to molar 3—1/2 natural size, after Ameghino. MEASUREMENTS, SPECIMEN 3179 Upper dentition, molar 1, length 46 mm., width 50 mm. Upper dentition, molar 2, length 51 mm., width 55 mm. Upper dentition, molar 3, length 50 mm., width 51 mm, Lower dentition, from Ameghino’s measurements Lower dentition, premolar 4, length 28 mm., width 23 mm. Lower dentition, molar 1, length 34 mm., width 24 mm. Lower dentition, molar 2, length 46 mm., width 24 mm. Lower dentition, molar 3, length 76 mm., width 23 mm. Only the distal end of the scapula has been found; and this shows a shallow glenoid cavity, which is much longer in the antero-posterior direction, than in the transverse. The spine rises close above the rim of the glenoid, and is unusually heavy. The lower half of the humerus is present, and character- ized by very wide epicondyles, a shallow supratrochlear fossa, a moderately deep anconeal fossa, no foramen, and a wide shallow trochlea. The ulna, according to Gaudry, is a long, heavy, nearly straight bone, with a shallow sig- ASMODEUS OSBORNI 137 moid notch, and with a large olecranon process which is not bent backward to any marked degree. The proximal ep Peet nD Ver a Te ry Nag SIS IRENA Fg EN ap pen Fig. 04. Humerus, anterior side— Fig. 95. Ulna anterior side— 1/5 natural size. 1/5 natural size, after Gaudry. end of the radius has a broad doubly curved articular surface to fit the full width of the humeral trochlea. Its ulna facet is a short broad area just below the margin of the bone, and would indicate little or no rotary motion of 138 THE DESEADO FORMATION OF PATAGONIA the fore arm. Most of the shaft is lacking but what is present indicates a very slender bone. The tibia is also a rather light bone of moderate length, and is strongly curved inward, the inner margin being Fig. 96. Upper end of radius, ulnar side—r1r/5 natural size. Fig. 98. Astragulus, dorsal aspect—1 /2 natural size, after Ameghino. : ana Fig. 09. A, Ungual phalanx, Fig. 07. Left tibia, posterior No. 3; B, Ungual phalanx, No. side—1/5 natural size. 5—r/2 natural size. especially concave. On the wide proximal end, the inner condyle is concave, the outer convex, the two being sep- arated by a prominent bifid spine. The shaft is slender, with a deep groove down the anterior face especially at the ASMODEUS OSBORNI 139 upper end, while on the posterior face, there is a large interosseus crest, which starts just below and external to the spine, and extends in a sigmoid curve three-fourths of the length of the shaft, ending on the internal border Distally the tibia is flattened antero-posteriorly, and the internal margin extends as a wide process down to the level of the navicular face of the astragulus. The articular facet for the astragulus is a rectangular depression, being about half as wide in the antero-posterior direction as in the transverse. This facet is only slightly concave and the inner and outer portions are not separated by an inter- trochlear ridge. The fibula has not been found, but the tibia shows no indication of its having been fused to it. Ameghino has figured the astragulus as very low, with the trochlea flattened, the internal condyle being wider and flatter, while the external condyle is narrower and somewhat raised. The trochlea is peculiar in that its proximal margin 1s deeply notched by a depression in which there is a large perforation. The neck is prolonged and carries a large convex head articulating with the navicular only. The measurements given are, length 116 mm., width 75 mm. Gaudry figures a calcaneum, showing a long narrow tuber, and the facet for the fibula as a wide shelf which projects strongly on the external side. The size as given by Ameghino is 240 mm. long, by 120 mm. wide. I have two associated ungual phalanges, one of which corresponds to that figured by Ameghino as the third. It is high, laterally compressed, has a very rugose surface on either side, and a deep cleft in the end. This is 68 mm. long. The second ungual is very asymetrical, also laterally compressed, and with the point curved inward. I take it to be the fifth. The tibia, the tarsus, and the phalanges strongly suggest that this animal walked on the side of its foot. 140 THE DESEADO FORMATION OF PATAGONIA Asmodeus scotti Ameghino A. scotti Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 643. A. scotti Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 477. This species is not represented in our collection, but I reproduce Ameghino’s figure of the type, and of the milk Fig. too. Upper and lower incisors, canines, and premolars ——1/2 natural size, after Ameghino. dentition. Unfortunately his type figure is from the side and does not give all the desired information. In the upper dentition, the small incisors, pitted on the crown, increase regularly in size toward the rear; and each has an external cingulum around the base. ‘The canine is about twice the size of the adjacent incisor, and also has V hia diz dtl ge dpm. 4 mt Fig. tor. Milk incisors, canine, and premolars and permanent m. 1—1/2 natural size, after Ameghino. an external cingulum. ‘The premolars increase regularly in size and also have at least an external cingulum. Figure 101 shows a dentition which Ameghino described as the milk set of A. osborni. At the same time he remarks the unusual character of the deciduous canine in being two- cusped. I think this set of teeth should be interpreted as deciduous inc. 2 to deciduous pm. 4, plus the permanent ASMODEUS SCOTTI 141 molar t. With such an interpretation, we find the incisors normal, the canine normal though not as large as in the permanent set, and the two-cusped tooth is the first milk premolar. The last tooth in the series is considerably different from the premolars and is evidently permanent molar 1, which is about the size and character of this tooth in A. scotti, much too small to belong to A. osborni. This set of milk teeth differ from the permanent teeth in that the premolars do not have the anterior, inner and posterior cingulum, characteristic of the permanent dentition. The following measurements are taken from Ameghino: Upper dentition, inc. 1 to pm. 4 104 mm, Upper dentition, premolar 2, length 18 mm., width 25 mm. Upper dentition, premolar 3, length 20 mm., width 28 mm. Upper dentition, premolar 4, length 23 mm., width 35 mm. Upper dentition, molar 1, length 28 mm., width 39 mm. Upper dentition, molar 2, length 37 mm., width 44 mm. Upper dentition, molar 3, length 50 mm., width 48 mm. CHAPTER x] ASTRAPOTHERIA THIS group 1s composed of large, long limbed creatures, with a highly specialized dentition, in which the canines of the upper jaw are developed into great curved tushes, resembling those of Pyrotherium; while the canines of the lower jaw are compressed in the antero-posterior diameter and protrude laterally, like those of pigs. Upper pre- molars 1 and 2 are reduced or lacking, while pm. 3 and 4 are also reduced, but usually retained. The upper molars are brachydont, and have a crown very like that of the molars of homalodontotheres. The lower incisors are small, proclivious, and set at intervals around the broad semicircle of the front of the fused lower jaws. The lower canines are permanently growing teeth, smaller than the upper canines, project laterally, and have the tips recurved. Premolars 1 and 2 are usually lacking, pm. 3 more or less reduced, and pm. 4 is a normal, short, molariform grinder. The lower molars have the same basal pattern as in Tovxodonta, the crown carrying two crescents with a plump pillar in the basin of the posterior crescent, the pillar, however, being situated far forward near the anterior horn of the redr “Crescent. Lydekker made an order Astrapotheria including the Astrapotheria and Homalodontotheria, but as the dentition of the two groups is so different, because of the enormous enlargement of the frontal region, and because of the reduction of the premolars, | am convinced that these two groups represent totally divergent lines of develop- ment; and I have therefore made each of the groups a . separate suborder. PARASTRAPOTHERIUM 143 Ameghino has described several genera, which make a progressive series and show a constantly progressive variation as far as they are known. GENUS FORMATION FORMULA Albertogaudryi Casamayor ; i 3. Post. inner and post. I . . 2 median. cusps isola- ted. Astraponotus Astraponotus i232 3. Post. inner cusp, uni- aN ted with wall making small lobe. Parastrapotherium Deseado and Colpodon #123 Post. lobe large, also Se i a strong crista. Astrapothericulus Astrapothericulus as 31253 Astrapotherium Santa Cruz S228. 3s In the Deseado beds, beside Parastropotherium, Ame- ghino has described Liarthrus, based on an upper second premolar and part of another tooth, but I can see no structural variation from Parastropotherium or indeed from P. holmbergi; so 1 consider this genus as a synonym. As to the genus Traspoatherium, 1 can not see in it any reason for making a genus separate from Parastrapotherium. Parastrapotherium Ameghino Parastrapotherium Amegh., 1895, Bol. Inst. Ceog. Argen., t. 15, p. 636. Parastrapotherium Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 449. Liarthrus Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 641. Liarthrus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 451. Traspoatherium Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 641. Traspoatherium Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 450. The genus, in general, is similar to Astrapotherium, so that Gaudry considered it the same, but Ameghino has distinguished it by the tushes being relatively of smaller size, the lower incisors larger, and by the presence of pm. 3 144 THE DESEADO FORMATION OF PATAGONIA in the lower series. The Deseado forms are also of con- siderably larger size than the Santa Cruz. Our material includes a pair of lower jaws, two scap- ulae, the humerus, and the lower end of the femur. — No skull has been found in the Deseado. Those from the Santa Cruz are enormously swollen over the orbits, the massive bone making a skull wholly unique. The lower jaws are similar to those of Astrapotherium, except that the rami are deeper. The front ends are fused and expanded making the anterior much enlarged, and causing the incisors to stand at intervals as in Coryphodon. ‘The symphysis is massive and prolonged backward nearly to premolar 3. The rami are plump and unusually thick. Fig. 102. Upper dentition of Astrapothericulus iheringi— 1/2 natural size. Of the upper dentition, Ameghino figures only the first molar and the canine. I have given Ameghino’s figure of the upper dentition of Astrapothericulus, to indicate what this would be like, for the variation is only slight. The canine is a great tush, not unlike the incisor-tush of Pyrotherium, oval in cross section with the greater diameter from front to back. The first and second premolars have disappeared. Premolars 3 and 4 are greatly reduced. The molars are very like those of Asmodeus, large brachy- dont grinders, composed of an outer wall, and an anterior and posterior lobe. The external cingulum is a_ trace only, and the internal cingulum is developed in varying degrees. The basin is deep and subdivided by a crista which rises from the external wall, and as the surface is worn off unites with the anterior lobe, cutting off a small PARASTRAPOTHERIUM 145 pit. Behind the posterior lobe is a small basin, bounded in the rear by a second crista from the rear end of the external wall, which, as the tooth is worn down, unites with the posterior lobes, cutting off a small posterior pit, suggestive of that of homalodontotheres. The three lower incisors are expanded at their ends into thick shovel-like crowns, each with a strong crescentic cingulum on the posterior face, and with a shallow furrow on both the front and back faces. Relatively the incisors are much larger and longer than in Astropotherium. The lower canine is flattened on the upper face, so that its cross section is close to semicircular making a typical permanently growing rooting implement. This tooth is relatively shorter and smaller than in Astrapotherium. Premolars I and 2 are wanting, a long diastema occupy- ing the interval between the canine and pm. 3. Premolar 3 is greatly reduced in size, and in my specimen has fallen out, being represented by a small alveolus. I judge that in old individuals it falls out. The fourth premolar and the molars are typically those of Toxodontia. The young show two plump crescents, with a low plump pillar, sit- uated near the anterior horn of the posterior crescent, which pillar, as the tooth wears, unites with the anterior horn. The scapula is a remarkably heavy and elongated bone, greatly arched where it lay over the ribs. The spine is high and heavy, with the upper margin developed into a thick ridge like a banister rail, which is prolonged in front to, or a little beyond, the level of the glenoid fossa, this distal portion being expanded into a broad plate more than half as wide as the widest portion of the blade of the scapula. The glenoid fossa is relatively small, oval in outline, and with the long axis parallel to the long axis of the body. The anterior margin of the articular surface is reflexed, apparently to come in contact with the base of the greater tuberosity of the humerus. This glenoid cavity 10 146 THE DESEADO FORMATION OF PATAGONIA is only large enough to actually cover about half of the head of the humerus, and fits so that, in a position of rest, the glenoid covered the outer part of the humeral head, and only articulated on the inner part of the humerus head when the limb was bent inward. The blade of the scapula is narrow, with the proximal end prolonged and ending in a thick rugose mass. The anterior and posterior mar- gins are rugose and thickened, the great thickness of the proximal end being due to the convergence of these thick- ened margins and the heavy spine. Lastly, this thick proximal end is peculiar in having on its posterior side a large rugose cavity, which was apparently to receive mus- cular attachments. For such a heavy animal, the humerus is extraordinarily long and slender. The sessile head is strongly compressed from side to side, very convex, and much larger than the glenoid fossa, its articular surface extending onto the base of the greater tuberosity. This tuberosity is heavy and thick, but does not project above the head. The powerful deltoid ridge extends from the tuberosity two-thirds of the way down the shaft. The shaft is unusually slender. Distally it expands laterally to make the two large epicon- dyles, of nearly equal size. The trochlea is relatively narrow, the internal surface being the narrower, and rising to a high margin; while the external portion is wider, rounded, and has a low margin. The supratrochlear fossa is moderately deep, the anconeal fossa somewhat deeper, but there is no connecting foramen. Gaudry* figures a radius and ulna, both relatively long bones, and closely apposed; so that there was no possibility of a rotary motion of the forearm. The proximal end of the radius is expanded, so that its articular surface is in contact with the full width of the humeral trochlea on the anterior side. Below, the bone contracts to a moderately slender shaft, and then expands distally into * Anal. Palaeontologie, t. 1, p. 5, 1906. PARASTRAPOTHERIUM 147 a heavy club-like distal end. The ulna has a short but heavy olecranon process, with a prominent coronoid process. The sigmoid notch is shallow, but the articular surface expands on both sides, so that it covers the full width of the humeral trochlea on the posterior side. Dis- tally the ulna is not so heavy as the radius. Under the name Pyrothertum romert, Ameghino* figures a carpus and metacarpus, which Tourniert however assigns to Parastrapotherium, probably P. herculeum; and figures a carpus and metacarpus of the same type, but smaller, which he attributes to Parastrapotherium. 1, however, can not see how such a small foot can belong to so large an animal, and feel that, until evidence of direct association is given, it is best not to consider these feet as belonging to Parastrapotherium, but rather to Pyrotherium. Of the femur I have only the distal end, which, however, corresponds completely with the one figured by Gaudry. It is a long bone, slightly shorter than the humerus, with a small head, set on a short and poorly outlined neck. The greater trochanter is wide and rugose, rising to about the same height as the head. The lesser trochanter is not distinguishable. About the middle of the shaft there is a powerful third trochanter, which continues as a narrow ridge upward to the greater trochanter, and downward in a similar narrow ridge almost to the outer condyle. At the proximal end the shaft is greatly flattened, but in the central and lower parts becomes almost circular in section. The two condyles are set wide apart, project considerably behind the posterior face of the shaft, and and are only slightly convex. The trochlea is of moderate width, short, and shallow. Gaudry outlines a short, heavy, rugose caleaneum which has but a short tuber; a flat navicular; a small cuboid; and an astragulus with only a slight convexity of the * Bol. Inst. Geog. Argen., t. 18, p. 442, fig. 25, 1897. T Bul. Soc. Geol. France, ser. 4, t. 5, p. 305, 1905. 148 THE DESEADO FORMATION OF PATAGONIA trochlea, and with the navicular facet directed obliquely forward, making an angle of 127° with the plane of the trochlea, which, as he says, would indicate a semidigiti- grade position of the pes. The following species are distinguished by Ameghino as coming from the Deseado beds: P. holmbergi, P. trous- sarti, P. lemoinet, P. ephebicum, P. martiale, P. superabile, P. insuperabile. The various species are known from the same parts in but a few cases. Their relative sizes are indicated from the following compilation of the measure- UPPER LOWER LOWER| LOWER pm.4| m.1 | m.2] m.3 | pm.4| m.1| m.2 | m.3 | inc. 1] pm. 4 |—m. 3] ~m. 3 P. hatuaberat te 56-56) aa P. troussarti 24- 40- 57- 60- 180 P. lemoinei 34-34 A P. ephebicum arora 42-21 | P. martiale 30-42 82-83 | | 550 Drakes 30-43 | wi P.dnsuperabille 37-48 | 100-80) 34-23 he? bedi Se ee, ae P. (Liarthrus) co- pei 29-46 P. (Traspoathe- rium) convexi- dens 19-27 [ie | | Amherst specimen | 28-26| 43-28] 58-32 70-36 455 200 | P. holmbergi is the type species, and of considerable size, and to it I have assigned my material. In such a large animal, variations in size are to be expected. PP. troussarti, as described, is a tenth smaller than P. holmbergi, the only structural character differentiating it being the isolation PARASTRAPOTHERIUM 149 of the pillar in the lower molars, which is a character due to youth; so I have considered it a synonym of P. holmbergi. P. ephebicum is a much smaller and distinct species, with which I should associate the single upper molar to which the name P. Jemoinet has been given. P. martiale is a large species, distinguished by the strong development of the cingulum on the internal side of the upper molars, and on the inner side of the lower molars; and by lower premolar 3 being well developed with two roots. P. superabile is of the same size as the foregoing, but has the cingulum on upper premolar 4 (the only tooth known) less developed. I should therefore consider it a synonym of P. martiale. P. insuperabile is the largest species, and is distinguished by the excessive development of the cingulum. JLzarthrus is founded on an upper pm. 4 with a part of pm. 3, but, as far as I can see, does not differ in character or size from P. holmbergi. Traspoatherium is based on upper premolars which are distinguished by the roots being fused from side to side. I think it is an age character and for the present would consider it the same as P. holmbergi, probably the tooth being pm. 3. Parastrapotherium holmbergi Ameghino P. holmbergi Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 636. P. holmbergi Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 449. P. troussarti Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 638. P. troussarti Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 449. Liarthrus copei Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 641. Liarthrus copei Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 451. Traspoatherium convexidens Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. O4!. Traspoatherium convexidens Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 450. Parastrapotherium holmbergi Tournier, 1905, Bul. Soc. Geol. France, ser. 4, t. 5, p. 305. Astrapotherium holmbergi Gaudry, 1906, Anal. Palaeontologie, t. 1, p. 5. To this, the type species, I have assigned all the material we found on the Chico del Chubut, west of Puerto Visser, 150 THE DESEADO FORMATION OF PATAGONIA as enumerated under the generic description. The lower jaws belonged to an old individual. The humerus and scapulae were found associated, the femur isolated. Of the upper dentition, the only available measurements are those of Ameghino for the first molar, and the canine. Upper dentition, canine, length 256 mm. Upper dentition, molar 1, length 57 mm., width 57 mm. Fig. 103. Upper molar 1 of the left side—natural size, after Ameghino. The measurements of the complete pair of lower jaws which we found are Lower dentition, length from inc. 1 to m, 3 455 mm. Lower dentition, incisor 2, length 22 mm., width 22 mm. Lower dentition, canine, ant. post. diam. at alveolus 52 mm. Lower dentition, canine, trans. diam. at alveolus 26 mm. Lower dentition, diastema from c. to pm. 3 116 mm. Lower dentition, premolar 4, length 28 mm., width 26 mm. Lower dentition, molar 1, length 43 mm., width 28 mm, Lower dentition, molar 2, length 58 mm., width 32 mm. Lower dentition, molar 3, length 70 mm., width 36 mm. Height of mandible under molar 3 83 mm. The scapula is a very long heavy bone, with a narrow blade, and a high spine which has its upper margin thick- ened so as to appear like a banister rail. We found one complete scapula and a second incomplete one associated with it, which corresponded in all ways to the first one. PARASTRAPOTHERIUM HOLMBERGI I51 7h om el ph oa iis 4 t tQUEN ET YU nies p) ufpertt 4 Wf : ; ed Far | \ Fig. 105. Dorsal view of right scapula—1/5 natural size. Fig. 104. Lower jaws—1/5 natural size. 152 THE DESEADO FORMATION OF PATAGONIA Fig. 107. Left femur, posterior side—1/5 natural size; outline of upper portion after Gaudry from Astrapotherium Magnum, Fig. 106. Right humerus, posterior aspect— 1/5 natural size. PARASTRAPOTHERIUM HOLMBERGI 153 The following measurements are taken from specimen No«3328: Scapula, greatest length 694 mm. Scapula, greatest width 283 mm. Scapula, glenoid fossa, ant.-post. diameter 130 mm. Scapula, glenoid fossa, transverse diameter go mm. Scapula, height of spine 120 mm. Scapula, width of enlarged margin of spine at the lower end 170 mm. Scapula, width of margin in middle 45 mm. The humerus was associated with the two scapulae mentioned above, and is complete. For such a large animal, its length is excessive, greater than that of the species assigned by Gaudry to P. herculeum which species has a skull larger than that of P. holmbergz. Humerus, greatest length 720 mm. Humerus, greatest width across proximal end 248 mm. Humerus, least diameter of shaft 78 mm. Humerus, width across the epicondyles 220 mm. Humerus, width of trochlea on distal end 125 mm. The femur which Gaudry figures as belonging to A stra- potherium magnum corresponds, as far as the distal end will admit comparison, with the one which we found in the Deseado beds, so that in restoring the outline of the missing parts, I have based it on this A. magnum. Femur, length (estimated) 480 mm. Femur, width of distal end 135 mm. Femur, width of trochlea 57 mm. Parastrapotherium ephebicum Ameghino P. ephebicum Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 639. P. ephebicum Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 449. P. lemoinei Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 640. P. lemoinei Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 450. Astrapotherium ephebicum Gaudry, 1904, Mem. Soc. Geol. France, t. 12, p. 15. Ameghino based this species on a portion of the mandible of an old individual with molars 1 and 2. Its chief dis- tinction lies in its small size as compared with P. holmbergzt. Gaudry assigned to this species some upper teeth. We 154 THE DESEADO FORMATION OF PATAGONIA found no specimens of this species. The following are the measurements of the type according to Ameghino. Lower dentition, molar 1, length 3I mm., width 16 mm. Lower dentition, molar 2, length 42 mm., width 21 mm. Parastrapotherium martiale Ameghino: P. martiale Amegh., 1901, Bol. Acad. Nac. Cordoba, t. 16, p. 402. P. superablie Amegh., 1901, Bol. Acad. Nac. Cordoba, t. 16, p. 402. The species seems to have been founded on abundant material, representing an animal of larger size than P. holmbergi, which 1s dis- tinguished by the greater width of the crowns of the incisors, by straight canines diverging but little, by a strong cingulum on the outer side of the lower molars and the inner side of the upper molars, and by the narrow symphysis of Fig. 108. Upper molar 1 of the left side—natural size, atten ucenino: the lower jaws. P superabile was distinguished by a difference in the arrange- ment of the roots of upper pm. 4, but as the pattern of the crown is the same, as is also the size, I feel that this differ- ence is simply an individual variation. The following measurements are given by Ameghino: Upper dentition, length from pm. 3 to m. 3 240 mm. Upper dentition, premolar 4, length 30 mm. Upper dentition, premolar 4, width 43 mm. Upper dentition, molar 2, length 82 mm. Upper dentition, molar 2, width 83 mm. Lower dentition, length from inc. I to m. 3 550 mm. PARASTRAPOTHERIUM 155 Parastrapotherium insuperabile Ameghino P. insuperabile Amegh., 1901, Bol. Acad. Nac. Cordoba, t. 16, p. 403. This is the largest of all the species, and is distinguished by the enormous development of the cingulum on the anterior, inner, and posterior sides of the upper molars, the same being uninterrupted and so elevated, that the internal crests seem to rise out of a basin. The following measurements are taken from Ameghino: Upper dentition, premolar 4, length 37 mm., width 48 mm. Upper dentition, molar 3, length 100 mm., width 80 mm. Lower dentition, premolar 4, length 43 mm., width 23 mm. CHAPTER iXi1 PROBOSCIDEA Suborder Pyrotheria Tuts suborder was established by Ameghino to receive the peculiar genus Pyrotherium and related forms. These animals are of large size, massive build, with narrow elongated skulls, in which the nasal opening is situated far back, as in animals with a proboscis; with a tiny brain case surrounded by cellular spaces; with the maxillae, palatines, pterygoids and alispenoids developed downward, so that the palatal plane makes a strong angle with the basi-cranial plane; and with the occipital condyles high up on the back of the skull. Then the first and second upper incisors and the second lower incisors are developed into enormous tushes with enamel on the anterior sides only. The remaining incisors, the canines, upper premolar 1, and lower premolars I and 2 are wanting; the remaining premolars and the molars being developed into great quadrilateral grinders, each with two transverse crests. The neck is short, the limbs massive and short, especially the lower members of each limb, and the feet were probably five-toed. The relationship of these forms has been the subject of extended discussion: Ameghino seeing in this genus the ancestors of the Probiscidea, and comparing them with Palaeomastodon, Dinotherium and Barytherium, even finding resemblances to Diprotodon; Gaudry concludes that they are not proboscidians; and others have suggested that they were specialized toxodonts. I have prepared the following table of comparisons with Palaeomastodon, a toxodont, and Dziprotodon. PYROTHERIUM 157 to w ~ co ‘o Upper tush PyYROTHERIUM Inc. t enlarged PALAEOMASTODON Inc. t enlarged in Lower tush TOXODONT, DIPROTODON NESODON Inc. © reduced Inc. 1 tush Nasal opening Basicranial axis Over molar t Over molar 1 Plane of base of cranium bent up, makes 140° with plane of palate Plane of base of cranium bent up, makes 155° with plane of palate Moeritherium. |Inc. 2 caniniform Inc. 2 tush Inc. 2 tush tush Inc. 2 reduced Upper molars Bilophodont Bilophodont in |Rhinoceros-like |Bilophodont Mastodon and Dinotherium Inc. 2 (?) Inc. 2 ness Inc. I Lower molars Bilophodont 'Bilophodont in | Bicrescentric Bilophodont Mastodon and Dinotherium Over incisors Over diastema Plane of base of|Plane of base of cranium parallel] cranium parallel with plane of} with plane of palate palate Pterygoids Pterygoids plus alisphenoids make great verti- cal plates Petrygoids plus alisphenoids make great verti- cal plates Pterygoids normal|Pterygoids normal Jugal Takes small part on glenoid fossa squamosum Tympanic bulla Palatine bones Premaxilla Antorbital foramen Posttympanic process of 16 ‘Intercellular laminae ‘Atlas Axis Surrounds meatus, and crowds out. tympanic Takes small part on glenoid fossa Takes no part on|Extends to glenoid glenoid fossa fossa Surrounds meatus and crowds out tympanic Surrounds meatus|Not surround me- and crowds out! atus nor crowd tympanic out tympanic Small, inflated, hollow Narrow in front, expanding behind Crowded out from forming any por- tion of palate 2 foramena Present ‘Small, inflated, | hollow Large, inflated, hollow ‘Narrow in front, | expanding behind |Crowded out from forming any por- tion of palate 2 foramena |Present Long, has hypo- physis | Long, has hypo- physis Hemispherical odontoid ‘Rounded odontoid Wide in front, nar- rowing somewhat behind Makes front of|Fused to maxilla palate t foramen 1 foramen None None Long, no hypo-;Short, no hypo- physis physis Peg like odontoid|Odontoid slightly flattened on top 158 PYROTHERIUM PALAEOMASTODON THE DESEADO FORMATION OF PATAGONIA TOXODONT, DIPROTODON NESODON 17|Cervicals 3-7 Very short Very short Moderately long {Short 18| Humerus Flattened deltoid ridge with post. spur |Flattened deltoid ridge with post. spur Rounded no spur|Flattened distally, on deltoid ridge | tiny spur on del- toid ridge 9|/Radius and Ulna = Very short and massive Moderate length |Fairly long 20|Femur Flattened, Gr. tro- chanter low, no 3rd trochanter Flattened, Gr. tro- chanter low, trace of 3rd trochanter Rounded, Gr. tro-| Rounded, Gr. tro- chanter high, 3rd| chanter very low, trochanter no 3rd trochanter . nN 1| Tibia Short and massive, free from fibula Short and massive, free from fibula Moderate length,]Moderate length, fused to fibula at] free from fibula upper end Still other forms like Amblypoda and Arsinotherium have been suggested as having characters in common with Pyrotherium, and it is clear that, with such a variety of forms, some of the characters must be parallelisms due to a common adaptation, and only one of these varied groups can be the one to which Pyrotherium is related. For myself, | have made comparisons with the Amblypoda and Arsinotherium, and feel that such features as the mas- sive limbs, shape of individual bones, etc., are due simply to the fact that all these are massive animals. In the case of Arsinotherium, there are some characters which are also common to hyracoids and elephants, like the position of various basicranial foramena, the prolongation backward of the jugal and the shape of the palatines. My conclusion is that Pyrotherium is related to the pro- boscideans, and came from the same stock which gave rise to hyracoids, elephants and Arsinotherium. 1 think further that Pyrotherium belongs definitely to the pro- boscidean line. Referring back to the foregoing table. The develop- ment of tushes may be an adaptive character; but in the elepnants it is inc. 2 of the upper and inc. 2 of the lower PYROTHERIUM 159 jaw which are so developed. In Pyrotherium, in the upper dentition, it is also inc. 2 which makes the tush, and inc. 1 is enlarged as in Moeritherium, and, so far as we know, has not been reduced in later forms as it was in the elephant line. In the lower jaw we have no final evidence which will show whether it is inc. I or inc. 2 which makes the tush; but the lower tush bites against upper inc. 2 and I have considered it to be incisor 2. The loss of the teeth behind the tushes is a character to be expected in the development of tushes and gives no data. The bilophodont character of the back teeth has oc- curred many times in the animal kingdom and while it may be the inheritance of the early elephants it can not be used as an argument. The position of the nasal opening looks very much like that of elephants, but again is coincident with the devel- opment of a proboscis. However, this has not occurred a great number of times in the animal kingdom, and where it has, it takes a variety of forms of modification. In Py- rotherium, the modification is of the type in elephants, and elephants only. A very striking feature is the development of the dental region downward so that the basi-cranial axis is bent upward, making an angle of about 140 degrees. There are other cases of the bending of the basicranial axis; but in the other ungulates it is a bend downward, the reverse of what we find here and in elephants. To adjust the posterior part of the nasal chamber to this, the ptery- goids and the alisphenoids are developed into great wing- like plates on either side. I find this modification of the basicranial axis and of the palatal, pterygoid and _ alis- phenoid bones in no other group but the elephants. In Palaeomastodon it has been developed to a degree so that the angle is about 155 degrees. The back of the palatine bones is also characteristic, for these begin as narrow pointed bones and behind the 160 THE DESEADO FORMATION OF PATAGONIA last molar expand into wide plates, just as in Palaeomas- todon (and in no other groups), having the postpalatine foramen opposite or behind the last molar. The posttympanic region of the squamosum is modified so that this process unites with the anterior squamosal region to crowd out more or less completely the tympanic bone where it should surround the auditory meatus. This feature is common to the elephants, the hyracoids, and the toxodonts, so that I consider it a primitive feature indicative of the ultimate common ancestry of these groups. The tympanic bulla can be compared with that of elephants closely, and has much in common with that of toxodonts, but in this last group the tympanic is much more highly developed. The premaxilla bone in Pyrotherium is crowded out, so that it makes no part of the palate, which is a character of elephants, and in contrast to toxodonts or other groups which have been mentioned. There are two antorbital openings as in elephants, and a feature not common, though not unknown. On either side of the brain case are cellular spaces with intercellular lamellae, which are so characteristic of elephants; a confirmatory feature, though in itself not conclusive. \ The foramena on the base of the cranium are similar to those on the base of the cranium of elephants, though there are some variations, as for instance, the exoccipital foramen, is isolated in Pyrotherium, but fused with the posterior lacerum foramen in elephants, and other slight variations in position; but, on the whole, the foramena of Pyrotherium are much closer to those of elephants than of any other group. There is also much in common with toxodonts and with hyracoids, as would be expected if they have a common ancestry. There is no suggestion of a marsupial arrangement as would be necessary if related to Diprotodon. PYROTHERIUM 161 The atlas of Pyrotherium is peculiar in having a marked hypophysis which is unusual, but is a feature of the atlas of Palaeomastodon and Moerithertum. The axis is peculiar in that the odontoid is flattened on the upper side and very short and wide. In this the form is unique. The continuation of the articular surface on the lower side of the odontoid with the articular surfaces of the ant. cotyles is a feature also of elephants. The remaining cervicals are greatly shortened almost to plates, which is elephantine again, though this short neck 1s approximated by Dipro- todon, some Amblypods and Arsinotherium, so that it must be in general looked upon as an adaptive feature, though in its detail it shows again an elephant character. The upper members of the limbs are longer than the lower, which is common to many massive animals. The humerus is tremendously flattened from front to back, even more so than in any of the animals used for compari- son, though flattening is a feature of them and of the elephants the most so. With the flattening, the deltoid ridge is prolonged enormously making a crest along the outer side of the bone, which at the lower end rises in a prominent process, as in elephants (also in Diprotodon but in this case the rest of the bone is very different). In addition to this, the supinator ridge is prolonged up- ward until it almost meets the deltoid, ending in a sharp spur at the top. This spur is more marked in Pyrotherium than in elephants, although they show the same develop- ment of the supinator ridge. The femur has the head much higher than the greater trochanter, which is a feature common to elephants, Diprotodon, Arsinotherium, etc., so that it must be looked upon as an adaptation. The third trochanter has disap- peared, and in elephants, it is lost in the advanced forms, remaining however as a trace in Palaeomastodon. The tibia is very short and massive and hardly gives any suggestions of relationship, except that it is not fused It 162 THE DESEADO FORMATION OF PATAGONIA with the fibula at the upper end, in which it is in strong contrast to the toxodonts. While in the table of comparisons numbers 1, 2, 3, 4, 8,9; 10, 14; 17, 19, 20, and’ 21 ‘may. be, in partjsor wholly interpreted as adaptations, and alone would not be at all conclusive of relationship to elephants, numbers 1, 5, 6, 7, 8, II, 12, 13, 15, 18, and 21 point toward the elephants as the close relatives of the Pyrotheria. In the first series of points there are none which mitigate against associating these two groups, while if the attempt is made to associate Pyrotherium with any group other than Proboscidea there are strong points, and a number of them, which would prevent this association. As a result of the foregoing, together with a feeling which continued handling of the specimens has given me, I can come to no other conclusion than that the Pyrotheria should be placed under Probos- cided. In his Linea Filogenetica de los Proboscideos, Ameghino assigns to this suborder, or at least puts into the phylo- genetic tree, a considerable number of forms from the Casamayor beds, all of them genera with bunodont mo- lars, usually known by but one or two teeth, such as A smith- woodwardi, Nephracodus, Cephanodus, Paulogervaisia, and the better known genera, Carloameghinia, and Dido- lodus, all of which he makes ancestral to Pyrotherium. So far as known, however, these forms show none of the peculiarities of the Pyrotherium skull or dentition, so that it is difficult for me to see any reason for including them even in the suborder. The genus Carlozitielia, from the upper Casamayor, is in a different position, having an enlarged upper incisor (found isolated) and molars of the bilophodont type. I should include this in the family Pyrotheridae and none of the others. PYROTHERIUM 163 Pyrotheriidae Ameghino All the forms assigned to this family are supposed to be closely related to Pyrothertum and to have much the same structure. Ameghino has proposed the following genera, Pyrotherium, Parapyrotherium, Richardowenia, Archaeolo- phus, Propyrotherium. Parapyrotherium is based on a small molar and a tush which Ameghino first described as Pyrotherium planum, later elevating the species to a genus, designated as Para- pyrotherium, differentiated by the transverse crests being low and the valley at either end being blocked by an intertubercular ridge. (Gaudry considered that this genus represented either the milk teeth of P. romer?, or a variation of that species. I can not see the basis of a new genus in the material. The genus Richardoweni is based on half of a molar, which has the transverse crest interrupted in the middle. Too little is known of this form to base a valid genus or even to associate it with Pyrotherium. Archaeolophus is founded on a small tush and part of an upper molar, also inadequate material for a genus. It is probably Pyrotherium. Propyrotherium is a smaller form from the Astraponotus beds, apparently a good genus; the type species being P. saxeum, of considerable smaller size than any of the Deseado species. The distinctive features of the genus can not be given until more material is known. Carlozitielt is based on a small form from the Casamayor with narrow molars. An incisiform tush is associated with the molar, which, if correctly associated, would indicate a wide deviation from Pyrotherium, and would probably be an ancestral form. A second species is reported from the lower Deseado beds, but I am a little skeptical as to the horizon. 164 THE DESEADO FORMATION OF PATAGONIA Pyrotherium Ameghino Pyrotherium Amegh., 1889, Actas Acad. Nac. Cienc. Cordoba, t. VI, p. 617. Pyrotherium Lydekker, 1894, Anal. Mus. La Plata, Palaeontologia Argentina pt. 3, p. 4. Pyrotherium Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 609. Pyrotherium Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 441. Pyrotherium Amegh., 1902, Anal. Mus. Nac. Buenos Aires, ser. 3, t. 1, p. 19-43. Pyrotherium Amegh., 1902, Anal. Mus. Nac. Buenos Aires, ser. 3, t. 1, p. 223-4. Pyrotherium Gaudry, 1909, Anal. Palaeontologie, t. 4, p. 1-28. Parapyrotherium Amegh., 1902, Anal. Mus. Nac. Buenos Aires, ser. 3, t. I, p. 29. The type species of the genus is P. romeri, which is however a rare species, most of the material and the best known belonging to P. sorondoi. The Amherst Collection contains a skull, complete except that the top of the brain case is crushed in and the parietals lost; a second skull with the full upper dentition but lacking the cranium; four lower jaws; two isolated tushes; the atlas, axis, and crevicals 3 and 4; the humerus; the proximal end of the femur; and part of the front foot; all from the Chico del Chubut west of Puerto Visser. Gaudry had upper and lower dentition and the fore and hind limbs except the feet. Ameghino described the upper and lower dentitions and a fore foot, so that with our material we now have a dasis for a fairly complete discussion, the vertebral column being the major part which is still lacking. The first striking feature is the dental formula. As formerly given, it is inaccurate, there being two great tushes on either side of the upper jaw, instead of one, as described. At first sight, I thought it might be a meristic variation, but both of my skulls show the same arrange- ment on both sides, and these are the first two skulls which have been found complete to the front end, and neither is by any means a young individual. The dental formula would then read +234. Upper incisor 1 is a rootless, permanently growing tush about a fourth smaller than inc. 2, but of the same PYROTHERIUM 165 character, being oval in cross section and having enamel on the front face only. These first incisors are directed downward, so that their ends stand between and very slightly in front of the second incisors. The end of each. is worn bluntly round in contrast to the beveled end of inc. 2. The second incisor is larger, rootless, and perma- nently growing, with a hollow base, enamel on the front face only, and oval in cross section. Both these teeth have a layer of cement on them, extending some distance beyond the alveolus. The tips are worn in a long bevel on the posterior side, very much as is the case on the incisors of rodents. The third upper incisor, the canine, and premolar 1 are lacking, a long diastema occupying their place, out of which they have been crowded by the development of the enormous root of inc. 2, which extends 150 mm. and more back into the jaw. P. romeri is distinguished from the others by pm. I being present. The teeth of the upper premolar-molar series have their crowns expanded, and the two series of either side have moved toward each other; until in front they are in con- tact while in the rear they are only 50 mm. apart, narrowing the palate in a unique manner, and giving the impression that the palate is mostly a grinding surface. The pre- molars are completely molariform and the whole series is at an advanced stage of specialization. Premolar 2 is three-rooted, with a triangular crown on which are three mamma-like tubercles, the larger one in front, and two behind. As the crown is worn, these unite into a flat, grinding surface, surrounding a central pit which opens behind. Premolars 3 and 4 and all the molars are large, four-rooted, quadrilateral teeth, each with two transverse crests running clear across the crown, and with a small cingulum across the anterior margin. Before they are worn, the top of each crest is tuberculated, and the cingulum is crenulated. In wearing, the anterior face 166 THE DESEADO FORMATION OF PATAGONIA of each crest is ground down; so that instead of the crown wearing to a level surface, it retains throughout life two oblique grinding surfaces. The lower dentition is more reduced than the upper. When in position, the tips of the two lower tushes diverge, so as to come in contact with the tips of the second upper tushes, from which I conclude that the lower tush is the second, rather than the first incisor, the latter having been lost when the second became enlarged as was the case in elephants. This lower tush has the same oval cross sec- tion, enamel on the front face only, and beveled tip as the corresponding upper incisor; but, in the same individual, is somewhat longer and slenderer. When isolated, how- ever, it is difficult to tell whether one is handling a small upper tush or a larger lower one. The remaining incisors, the canine, the first and the second premolars are wanting, and their place is taken by a small diastema. ‘The lower premolars and the molars are similar to those of the upper jaw, except the cingulum is on the posterior margin, and the wear is on the posterior face of each transverse crest. The skull is very long and narrow, with wide and deep zygomatic arches. ‘The nasal opening is moved back from the front of the snout to just opposite the orbit, leaving a long, narrow, but heavy snout, made up mostly of the premaxillae, on the anterior end of which is an oval boss, which must have served as an attachment for muscles. With the tushes developed so as to bite against each other, as in a gnawing animal, I can not see any possibility for the development of a pendant proboscis, but think that the snout must have been developed more like that of a pig, but probably to a greater degree. ‘The premaxillae are long and heavy, and prolonged backward to contain the roots of the great tushes; but these bones are not developed on the palatal side of the snout at all. The maxillae are also massive, carrying the premolars and molars, PYROTHERIUM 167 and extending forward to the bases of the tushes. They have developed downward so as to carry the plane of the palate far below the plane of the basicranium, and causing the upward bend in the basicranial axis, which is so characteristic of elephants. This bend leaves the occipital condyles a full foot above the plane of the teeth. The maxilla extends upward so as to bound the major part of anterior margin of the nasal opening, and of the orbit, which latter opening is small and directed forward. The zygomatic process is large and makes a considerable portion of the arch. The jugal is a broad flat bone making up most of the zygomatic arch and extending back so as to take a small part in making the glenoid fossa, as in elephants. The top of the brain case was crushed in before the burial of the animal, the anterior part being present, and about 40 mm. below its normal position, but the parie- tal region having been loose, exposed the brain cavity, the ear chamber and some of the cellular vacuities. The nasal bones are long and light in build, and are pushed back so that they lie between the postorbital processes of the frontals. ‘The frontals were united medianly, and_ pro- longed on either side of the nasals to make the postorbital processes. ‘The back margin of the frontals is broken away. ‘The parietals are lost, but it is apparent that there was a short sargittal crest. From the middle, high lamb- doidal crests extend to either side, and become continuous with the upper margins of the zygomatic arches. ‘The posterior face of the skull slopes back from the lambdoidal crests for a considerable distance, down to the moderate- sized foramen magnum. The squamosum is a large bone, with the lambdoidal crest and the extension of the zygomatic arch on its upper surface. It carries the major part of the glenoid fossa. Behind the auditory meatus is a large post-tympanic portion which extends down and unites with the pretym- 168 THE DESEADO FORMATION OF PATAGONIA panic portion, completely inclosing the opening of the ear and crowding the tympanic from being exposed on the side of the skull. There is a very short paroccipital process, and this posterior portion of the squamosum is the part which resembles that of elephants, hyracoids and, to some extent, Toxodontia. There is, however, no cavity in the squamosum as in toxodonts generally. The tympanic bulla is small, but little swollen, and hollow. It is quite exactly like that of probocideans. The basi- occipital is fused to the exoccipitals. The occipital con- dyles are very high above the plane of the teeth, are set wide apart, and are cylindrical bosses which would not allow a free movement of the head laterally, but only in the up and down direction. This last is again a feature of the elephants. The pterygoid bone is greatly enlarged to compensate for the bend in the basicranial axis, and the pterygoids, together with the alisphenoids, make broad plates bounding either side of the posterior nasal chamber, exactly asin Palaeomastodon. The palatal bones are slender in front, and broaden toward the rear, again, asin elephants. On the interior of the brain case is the cavity for the brain which indicates that this organ was of diminutive size, measuring about 150 mm. in length by 50 mm. in width at the widest part. It indicates a brain with very small cerebral hemispheres, which, however, had a swollen posterior margin, a larger cerebellum, and a wide medulla oblongata. The impression which I obtained of this brain is strikingly like that given for Palaeomastodon. On either side of the brain cavity are a couple of vacuities, apparently for lightening the weight of the skull. At the inner end of the auditory meatus is a large ear chamber, divided into a smaller anterior or cochlear portion, and into a larger posterior ear chamber proper. In figure 109, I have placed a diagram of the base of the skull of Pyrotherium, along beside that of Palaeomas- todon, for comparison of the basicranial foramena. The PYROTHERIUM 169 Fig. 109. Palatal views of the basicranial region of A. Pyrotherium, and B. Palaeomastodon, for comparisons; alc., alisphe- noidal canal; als., alisphenoid bone; Bsp., basisphenoid bone; ew., Eustachian canal; f./.m., foramen lacerum medium; f.l.p., foramen lacerum posterior; f.o., foramen ovale; 7.c.c., foramen for the internal common carotid; mx., maxilla; oc.f., occipital foramen; pal., palatine bone; ~.p.f., post-palatal foramen; pf., pterygoid bone; pt.s., and p.ty.sqg., post-tympanic process of the squamosum; sqg., squamosum; st.m.f., stylomastoid foramen. 170 THE DESEADO FORMATION OF PATAGONIA skull of Palaeomastodon is somewhat more elongated, especially in the posterior part. In both, there are two antorbital foramena; the postpalatal foramena of Pyro- therium are a trifle further back, but this palatal region in both is of the same type which is peculiar to elephants and Pyrotherium. In Pyrotherium the condylar foramen is separate, while in elephants it is fused in with the fora- men lacerum posterior. ‘This latter foramen in both cases is situated just back of the tympanic, and in Pyrothertum is of considerably larger size than in Palaeomastodon. The foramen lacerum medium is in front of the tympanic and in Pyrotherium appears considerably larger, mostly because it is under the margin of the tympanic in Palaeo- mastodon. ‘The foramen for the internal common carotid in Palaeomastodon pierces the tympanic bone just to the inside of the middle line, while in Pyrotherium it is on the outer margin of the tympanic. “The Eustachian canal is on the external border of the tympanic in both cases, but in Pyrotherium it is further back. The foramen ovale of Palaeomastodon is in the posterior part of the alisphenoid bone, but with the shorter alisphenoid of Pyrotherium, this foramen is pushed back to the posterior margin of the bone. In both cases, the alisphenoidal canal starts under the base of the fused alisphenoid and pterygiod, and opens into the orbit. The stylomastoid foramen of Pyrotherium is situated further out than in the case of Palaeomastodon. ‘The fusion of the postympanic portion of the squamosum is, in Palaeomastodon, much further advanced than in Pyrotherium, so that the passage to the ear is not apparent in the basal view of the former, but makes a considerable notch on the under side of the skull of Pyrotherium. The mandibles are excessively thick and heavy, being united at the symphysis, which extends back to the front of the second molar. ‘The ascending rami are prolonged back- ward, but do not rise above the level of the articulation. PYROTHERIUM 171 The atlas is a massive vertebra with the anterior cotyles deeply excavated, especially on the upper side, so that, as Gaudry suggested, the head must have been carried low. The flat posterior cotyles face obliquely downward. The neural arch is light and without a spine or an opening for the vertebral artery. ‘The basal portion of the bone, how- ever, is excessively heavy and thick; the socket for the odontoid process not reaching to the middle of the basal bar. The neural canal is oval in section, being a good deal wider than high, and of small size. The transverse proc- esses are short, heavy projections, adapted to receive heavy muscles. On the ventral surface there projects from the posterior margin a strong hypophysis, which, as Gaudry has pointed out, is unusual, but which is a character of the atlas of the Palaeomastodon. The axis is a short, heavy bone, with the anterior cotyles facing obliquely upward, a small neural arch, no spine, and with a thick odontoid process, which has the form of a quarter of a hemisphere set onto the front of the centrum. Cervicals 3 and 4 are very short vertebrae with light neural arches and no spines. ‘The neural canal is fully three times as high as wide. ‘Thus it is entirely evident that the neck of Pyrotherium was extremely short, as is the case with elephants, which alone would not be sig- nificant, but coincides with many other elephant features. Gaudry described a lumbar vertebra which is also a short, heavy bone. Otherwise the vertebral column of Pyro- therium is unknown. The distal end of the scapula is described by Gaudry as indicating a short, heavy bone, with the glenoid cavity compressed so as to be about twice as long as it is wide. The coracoid is a short, blunt process. ‘The spine was broken off, but enough remained to indicate a moderately high spine, prolonged toward the humerus, and bent some- what forward. 172 THE DESEADO FORMATION OF PATAGONIA The humerus is a very characteristic bone, short and stout, but greatly flattened from front to back. It has a large sessile head, which is strongly convex, and projects internally over the margin of the shaft. The external tuberosity is large and rugose but does not project above the level of the head. The deltoid ridge is shifted to the external side of the bone, and makes a long, muscular ridge, while on the opposite external margin is a second ridge, and between the first and second ridges a long furrow or trough is inclosed. These terminate just below the middle of the bone in roughened bosses, which all but meet. The epicondyles are large and give the excessive width to the bone. The external condyle is prolonged upward and ends in a spur. The trochlea is of moderate width and gently undulated. The supratrochear fossa is only slightly depressed, and the anconeal fossa is likewise shallow. The bone has no exact counterpart, but is simi- lar to that of Moeritherium and Palaeomastodon, but in each case is more flattened and has the external ridges more developed. Gaudry describes the radius and ulna. They are ridiculously short, and very massive. The ulna is stout with a massive olecranon which is directed well toward the rear. The sigmoid notch is shallow, the coronoid process short, and the articular area expanded so that the ulna covers the whole of the posterior of the trochlea of the humerus. The upper end of the radius is compressed antero-posteriorly, but distally it expands into a heavy bone. Its upper articulation is expanded, so that it comes in contact with the full width of the anterior portion of the trochlea of the humerus. The carpus and front foot are of questionable associa- tion. Ameghino described a front foot as P. romeri, and later Tournouer assigned this foot to Astrapotheriwm. However, I have seen no reason to think it belongs to Astrapotherium, being far too small, and.so would for PYROTHERIUM 173 the present consider it as belonging to Pyrotherium. We found a couple of metapodials evidently belonging to the foot as described. This carpus is of the primitive type, the sca- phoid and luna being large and receiving the radius; while the pyramidal is smaller, low and broad and received the ulna. The trapezium is larger than usual, being elongated and standing out 1 from the trapezoid, and support- - Fig. r1o. Left carpus and metacarpus, ing a reduced first metacarpus. outlines after ‘Tournouer—1/5 natural The trapezoid is also large and almost square in outline. The magnum is smaller and con- siderably flattened. The unciform is very large. These last three mentioned carpals carry the three medium meta- carpals which are quite normal and seem to have carried most of the weight of the animal. Metacarpus V articulates on the outer side of the unciform. It is a massive nodular bone with but a tiny articulation for the phalanx, which seems on this toe to have been reduced. Metacarpals IV, II], and II are short, stout bones, flattened from front to back, and enlarged at either end. On each, the trochlea extends well onto both the dorsal and palmar surfaces, thus giving the toes a considerable range of movement, and indicating at least a semidigitigrad mode of walking. Of the pelvis, the ilium is known as a broad, heavy bone with the acetabulum facing down. The hind limb is considerably longer than the front, and approximately pillar-like. The femur, as compared with the humerus, is quite a little longer, though, as femora go, it is not a long bone. The rounded sessile head stands high above the blunt, thick greater trochanter; the digital fossa is barely indicated; the rotular trochlea is short; the two condyles are subequal in size and set close together. The patella is short and nodular. ‘The tibia is short and very at Tir Ty 174 THE DESEADO FORMATION OF PATAGONIA heavy. The fibula is free its entire length and is a rather heavy bone. The astragulus is a lens-like bone with the trochlea but slightly convex, and the navicular facet directly below it, indicating a rectigrade foot. Ameghino established the following species, P. romert, P. sorondoi, P. giganteum, P. crassidens, P. trilophodon, P. pluteum. ‘This is a very considerable number of species of such a large type to occupy a limited region. Gaudry has lumped them all under species P. romeri. This, I think, is too drastic and I would find at least two species. It is true that there is great individual variation in such large animals, due to age, food supplies and individual vicissitudes; but where there is a difference of dental formula or a structural divergence I should consider these as specific in character. The type species is P. romeri (later spelled romerot) which was based on a first and second upper premolar and an upper tush, all of smaller size than P. sorondoi and differ- ing from all the others described in having pm. I present. Gaudry suggests that this may be the milk dentition but there is no evidence as yet to settle this, so I have left this species standing. Most of the material found by Ameghino, by Gaudry and by our party belongs to the type described as P. sorondot, which is somewhat larger than P. romeri, and lacks pm. 1 in the upper jaw. This then is the usual species and to it belongs most of what is known. It varies some in size but the characters are very uniform. P. giganteum is based on the root of a large tush, 90 by 70 mm. in cross section, which Lydekker associated with P. romeri, and which Ameghino later took as the type of a new species. | can see in this only a large individual of P. sorondot. P. crassidens is based on a last lower molar 90 by 80 mm. in diameter. It seems to me to be an upper molar and no larger than m. 2 in either of my skulls. P. trilophodon is based on a lower pm. 3, which, in every way, resembles the corresponding tooth PYROTHERIUM SORONDOI 175 in lower jaw of P. sorondoi. P. plutewm is based on three lower teeth of smaller size than the typical P. sorondot, but the difference is small and there are no structural features accompanying it; so I consider it simply a smaller individual of P. sorondoi. In the generic discussion, Parapyrotherium planum was also assigned to P. sorondot. Pyrotherium romeri Ameghino P. romeri Amegh., 1889, Act. Acad. Nac. Cience. Cordoba, t. VI, p. 618. P. romeri Lydekker, in part, 1894, Anal. Mus. La Plata, Palaeontologia Argen., t. III, supplement, p. 4. P. romeroi Amegh., 1894, Bol. Inst. Geog. Argen., t. 15, p. 612. P. romeroi Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 442. P. romeroi Amegh., 1902, Anal. Mus. Nac. Buenos Aires, ser. 3, t. 1, p. 32. P. romeri Gaudry, in part, 1909, Anal. Paleontologie, t. 4, p. 21. This species is characterized by the presence of pm. t which is absent in other species. The tooth is of fair size, two-rooted, narrow in front and has a narrow rim of enamel around it; and measures 22 mm. long by 14 mm. wide. The second premolar is 30 mm. long by 33 mm. wide. A lower tush is also associated with these two teeth and is of smaller size than in the following species, being at the alveolus border 40 mm. by 29 mm. in cross section. Pyrotherium sorondoi Ameghino P. sorondoi Amegh., 1894, Bol. Inst. Geog. Argen., t. 15, p. 613. P. sorondoi Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 443. P. sorondoi Amegh., 1902, Anal. Mus. Nac. Buenos Aires, ser. 3, t. 1, p. 30. P. sorondoi Amegh., 1906, Anal. Mus. Nac. Buenos Aires, ser. 3, t. 8, p. 331- P, romeri Lydekker, in part, 1894, Anal. Mus. La Plata, Paleontologia Argen- tina, t. III, supplement, p. 4. P. romeri Gaudry, in part, 1909, Anal. Paleontologie, t. 4, p. 21. P, giganteum Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 447. P. crassidens Amegh., 1902, Anal. Mus. Nac. Buenos Aires, ser. 3, t. I, p- 34. P. planum Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 446. Parapyrotherium planum Amegh., 1902, Anal. Mus. Nac. B. A., ser. 3, t. 1, p. 29. P. trilophodon Amegh., 1902, Anal. Mus. Nac. B. A., ser. 3, t. I, p. 33- P. pluteum Amegh., 1901, Bol. Acad. Nac. Cienc. Cordoba, t. 16, p. 386. P. pluteum Amegh., 1902, Anal. Mus. Nac. Buenos Aires, ser. 3, t. I, p. 29. The species varies in size and in the proportionate development of the tushes as would be expected in a large 176 THE DESEADO FORMATION OF PATAGONIA Fig. 111. Top of the skull—1/s5 natural size; Mate to in 1 on the left side is represented by an alveolus but the tooth had fallen out before the death of the animal; a.c., ear chamber; B, brain case; V, vacuities in the bone. 177 ‘usWIIDeds Ul UMOP poysnNid o1e YoTyM JeUoIZ puv yeseu Jo UoTzSOd SojeOIpUl sul] peop vy} ‘plosArsyd ‘y7q ‘:epIxeweid ‘'xwd trejowsid puoses ‘z-wd ‘epixew “xpy {aejour qsiy ‘repy teyesnt ‘tz azosiur ‘zz {apis IYSII Vy. WoO p910jser VUI;INO UI I JOSIOUT ‘72 S9zIS ;eAN}eU S/I—T]NYS 9u} 10 MIA APIG ‘ZII ‘SI yor -syesnt “¢ TOUT 2°) - 9plS JYSiI vy. WO] I I TOUT "I"? .9ZIS | YS OY} JO MIA VpIS I PYROTHERIUM SORONDOI I2 178 THE DESEADO FORMATION OF PATAGONIA and slow-growing animal. Most all of the material found by any of the collectors falls clearly into this species. Our specimens all came from the Chico del Chubut, west of Puerto Visser, which point is about 250 miles north of the locality where Gaudry’s material was found. The general features of the skull have been given under the generic description. The difference between this and the preceding species lies in the absence of pm. 1, and the somewhat larger size. Both of our major speci- mens are mutilated in places; and as the better skull was found with only the zygomatic arch exposed, we conclude that the parts missing were lost before burial. On the lower jaw the edges of some of the teeth were cracked off, and both the ascending rami are lacking, both things having happened before burial, this specimen being found well in the bank and never exposed to weathering. It appears as if the carcasses of the animals lay some time before being buried by the sediments. The scattered condition of all the finds indicates the same thing. The head of our femur is still marked by the teeth which cleaned the meat from the bone. The frequency of isolated tushes indicates that many jaws originally containing them have been either chewed to pieces or weathered away before burial. I do not think all the tushes found originally belonged to the lower jaw (Gaudry reports 18 tushes, all lower); for the upper and lower tushes when isolated are so much alike that it is difficult to distinguish them. The size of the skull isindicated by the following measure- ments: SPECIMEN No. 3207 Length from inc. 1 to occipital condyles 720 mm. Length from front of premax. to nasal opening 225 mm. Length of boss on premaxilla 77 mm. Length of nasal opening at top 80 mm, Width of nasal opening at top 88 mm. Length from premax. to lambdoidal crest 540 mm, Width across zygomatic arches 350 mm, Width across frontal bones go mm, Transverse diameter of the snout 115 mm, PYROTHERIUM SORONDOI Fig. 113. Base of the skull—r/s5 natural size; 7.1, incisor the right side grown over toward the center as its mate is wanting; 7.2, in- cisior 2; Pal., palatinum; Pi., pterygoid. 180 THE DESEADO FORMATION OF PATAGONIA The lower jaws were associated with the above skull, and are complete to behind the third molars on both sides. They are very short and heavy, especially in the anterior portion, the symphysis extending back to opposite the middle of the second molar. The height under molar 3 is 150 mm. See frontispiece. From the upper dentition, I give the measurements of my two chief specimens, together with those given by Ameghino for his type of P. sorondoi, and the figures given by Gaudry; from which may be seen the amount of variation which individuals may show. UprerR DENTITION SPECIMEN SPECIMEN AMEGHINO’S GAUDRY’S No. 3207. No. 3250 TYPE SPECIMEN Total length, inc. 1 to m. 3 530 mm, Inc. 1, length above alveolus — 133 mm. Inc. 1, antero-posterior diam. 49 mm. Inc. 1, transverse diam. 37 mm. 42 mm. Inc, 2, length above alveolus 174 mm. Inc. 2, antero-posterior diam. 59 mm. 77 mm, 65 mm. Inc. 2, transverse diam. 40 mm. 52 mm. 41 mm. Premolar 2, length 45 mm. 52mm. 48 mm. 40 mm. Premolar 2, width 36 mm. 40 mm. 30 mm. 29 mm. Premolar 3, length 46 mm. 49 mm. 48 mm. 40 mm. Premolar 3, width 57 mm. 57 mm. 46 mm. 48 mm. Premolar 4, length 47 mm. 51 mm. 46 mm. 43 mimi: Premolar 4, width 63 mm. 64 mm. 58 mm. 57 mm. Molar 1, length 55 mm. 55 mm. 57 mm. 55 mm. Molar 1, width 68 mm. 69 mm. 61 mm. 6r mm. Molar 2, length 63mm. 77 mm. 7oO mm, 57 mm Molar 2, width 85 mm. 93 mm. 75 mm. 68 mm. Molar 3, length 75mm. 68 mm. 83 mm. 64 mm. Molar 3, width 86 mm. 87 mm. 82 mm. 88 mm. For the lower dentition, I give the figures which Ame- ghino records for his P. sorondot, those given by Gaudry for his P. romert, and the measurements of specimen No. 3207. ‘The tushes in the lower jaw I would designate as incisors 2; because when the jaws are closed these diverge and their tips bite against the tips of the upper incisors 2. The first incisor seems to have been gradually lost and PYROTHERIUM SORONDOI ISI no space left for it in the front of the mandible, just as it was reduced and lost in the development from Moeritherium to Polymastodon or equivalent types. Fig. 114. Lower dentition—1/5 natural size; edges of teeth broken off in my specimen are indicated in outline. Lower DENTITION SPECIMEN AMEGHINO’sS GAUDRY’S No. 3207 TYPE SPECIMEN Incisor 2 to molar 3, length 510 mm. 540 mm.* 415 mm.* Premolar 2 to molar 3, length 325 mm. 280 mm. 272 mm. Inc. 2, length above alveolus 133 mm. 188 mm.* 168 mm.* Inc. 2, antero-posterior diam. 55 mm. 60 mm. 66 mm. Inc, 2, transverse diam. 40 mm. 36mm. 44 mm. Premolar 3, length 46 mm, 50 mm. 54 mm. Premolar 3, width 36 mm. 31 mm. 35 mm, Premolar 4, length 55 mm. 45 mm. 50 mm. Premolar 4, width 46 mm. 45 mm. 47 mm. Molar 1, length 65 mm. 50mm. 51 mm. Molar t, width 59 mm... 52 mm. 54 mm. Molar 2, length 73) iin. 56) mim. 66) mm. Molar 2, width 73mm. 63 mm. +66 mm. Molar 3, length 69 mm. 67 mm. 7I mm. Molar 3, width 74 mm. 66mm. 69 mm. Four cervical vertebrae were preserved with the skull number 3207, of which only about a third of the atlas is represented, but fortunately we found a complete atlas isolated and of the same size. The measurements for the atlas are taken from this separate specimen. While my skull, especially the teeth, seems to have been larger than the skull Gaudry described, the cervicals are a little smaller. I give the measurements of the cervicals which we found, comparing them with the figures given by Gaudry. * Figures taken from illustrations. 182 THE DESEADO FORMATION OF PATAGONIA Atlas, antero-posterior length (without hypophysis) Atlas, greatest width Atlas, height Axis, antero-posterior length Axis, greatest width Axis, width of odontoid process Axis, length of odontoid process Cervical 3, length of centrum antero-posterior Cervical 3, width of centrum Cervical 3, height of centrum Cervical 3, width of neural canal Cervical 3, height of neural canal Cervical 4, length of centrum antero-posterior Cervical 4, width of centrum Cervical 4, height of centrum SPECIMEN GAUDRY’S 3344 120 mm. 304 mm. 129 mm, SPECIMEN 3207 116 22 96 48 47 125 105 os) 22 45 132 105 mm. mm. mm. mm. mm. mim. mm. mm, mm, mm. mm. mm, 140 365 140 124 248 88 44 45 145 100 SPECIMENS Inm. mm. mm. mm. mm. mm. mm. mm. mm. mim. The humerus is flattened from front to back in a striking manner, so that, seen from the side, it looks most slender; while in reality it is a very broad bone, nearly straight, and with marked rugosities for the attachment of the muscles. We found but one specimen of the humerus, an isolated bone a little smaller than that described by Gaudry. Humerus, total length Humerus, width at proximal end Humerus, width at middle of shaft Humerus, antero-posterior diam. of shaft Humerus, width across epicondyles SPECIMEN No. 470 232 165 6I 230 3218 mm. mim. mm. mm. mm. GAUDRY’S SPECIMEN 500 232 170 mim. mm. mm. mm, We found neither the radius nor the ulna, but Gaudr ) figures both, giving the following measurements. Radius, length Radius, proximal diam. Ulna, length (calculated) Ulna, width of olecranon 245 127 280 140 mm. mm, mm. mm, PYROTHERIUM SORONDOI 153 [o4) Fig. 115. At., atlas; Ax., axis; C.3, third cervical; C.4, fourth cervical—1/5 natural size; apophysis of atlas is restored after Gaudry and the neural arch of cervical 4 Fig. 116. Axis—r/5 natural size, front is restored from the opposite side. view. Fig. 117. Anterior face of the humerus—1/5 nat- ural size, 184 THE DESEADO FORMATION OF PATAGONIA For the hind limb I give some of the figures which Gaudry gives accompanying his illustrations of the hind limb. Femur, length 630 mm. Femur, greatest proximal diameter 240 mm. Femur, distal diameter 170 mm. Tibia, length 370 mm. Tibia, greatest proximal diameter 164 mm. Tibia, greatest distal diameter 114 mm. Astragulus, antero-posterior diam. 123 mm. Astragulus, transverse diam. 114 mm, Astragulus, height 65 mm. CHARTER XItl RODENTIA W8HILE all of small size, numerically the rodents make about a third of our collection, the number of genera and species being, however, relatively small. All are hystricomorphs with the pattern on the crowns of the teeth relatively simple. While the incisors are typically rodent-like, permanently growing teeth, the molars are all rooted, some being entirely brachydont, others begin- ning to show hypsodont features. So far as yet known, the rodents make their first appear- ance in South America, in this Deseado formation. Were they, as Ameghino thought, developed there from such a form as Propolymastodon or Promysops of the Casamayor formation? Or did they migrate into Patagonia from some other section? For the former proposition to be convincing to me, it would require more complete material of the forms suggested than now exists.* Other groups of hystricomorphs occur in the Theridomyidae of the European Oligocene, and from the Oligocene of the Fayum. tf Either the old world forms are descended from the South American forms, or vice-versa. The two African lower jaws are very much like those of Cephalomys, and my feeling is that the Patagonian forms are derived from some immigrant reaching that section before Deseado times. The Deseado genera are not widely different from each -other, but it is evident that they are the representatives of at least two families, and my expectation is that other families will be found eventually to be already represented. * 1 have a lower jaw of Propolymastodon which, though not complete in front, gives me no suggestion that the incisor was rodent-like, and I am inclined to think that the incisor associated with the type of P. carlo-zitelli is a mistake. T Osborn, Bul. Amer. Mus. Nat. Hist., Vol. 24, p. 265. 186 THE DESEADO FORMATION OF PATAGONIA Our material does not permit the discussion of the skeleton or even of the skull as a whole, for the specimens occur only as isolated jaws, palates, or even as isolated teeth. In a few cases, the upper and lower dentitions are associated, but in no case was skeleton material clearly associated with the teeth. The remains look very much like such as are often found today in the western United States under a hawk’s nest or below the roosting place of owls. I think most of our specimens passed, before burial, through the stomach of birds or carnivors. Ameghino puts most of the forms in the family Cepha- lomidae, which he considers ancestral to Hystricomorpha | in general. I feel, however, that it is better to assign the Deseado genera to the families which have persisted until recent times, as Scott and Ameghino, in another place, have done. ‘There are six living families, four of which Scott found already represented in the Santa Cruz. ‘Two of these clearly may be continued back into the Deseado, the Erethizontidae, and the Chinchillidae, nothing as yet having been found to represent the Santa Cruz families Cavidae and Octodontidae. Chinchillidae In the Deseado, this family is represented by the genera Cephalomys, Scotamys, and possibly Litodontomys. Cepha- lomys is very abundant and seems to be ancestral to Pert- mys of the Santa Cruz; Scotamys is relatively rare but seems to be ancestral to Scotaeumys; while Litodontomys is also rare and as far as I can see without a successor. Cephalomys Ameghino Cephalomys Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 494. This is the common genus of the Deseado, over three- fourths of the specimens of rodents found belonging to one of its three species. Its dental characters mark it CEPHALOMYS 187 clearly. All the premolars and molars are rooted, though the crown is incipiently hypsodont, as much so as in any rodent of this period. The incisors are moderately large with the anterior face slightly convex, and the antero- posterior diameter comparing with the transverse diameter as 3 does to 2. The interval between the incisor and premolar 4 is moderate, indicating a short snout. Each lower molar consists of two transverse laminae separated from each other by an internal and an external infolding, both of which approach the median line but do not meet, a narrow, longitudinal bar separating the folds and connecting the anterior and posterior laminae. On the inner side, the posterior lamina has a furrow extending to the middle of the tooth, but only sinking into the crown about a fourth of its height, so that, with wear, it appears first as a bay, later as a pit, and finally disappears. In general it will be found only on molar 3, and may be wanting there on old individuals. On an unworn tooth, there occurs, on the inner side of the anterior lamina, a rudimentary pit corresponding to the one on the posterior lamina, but of much less depth, so that it is only occasion- ally seen, and that only on a very slightly worn tooth. The premolar differs from the foregoing in having a small median column on the anterior face of the anterior lamina. In three cases we found the deciduous fourth premolar (see fig. 119A), a complicated tooth, consisting primarily of three laminae in which furrows have developed until there are four folds or furrows on the internal side, sepa- rating five crests; while on the external side there are three furrows and four crests. Ameghino’s figure of this tooth in C. prosus has four laminae running clear across the tooth. I think the difference is due to his having an unworn decid- uous premolar whereas mine are all worn considerably. At first glance, the upper teeth appear strikingly differ- ent, resembling those of Perimys to which genus they are 188 THE DESEADO FORMATION OF PATAGONIA probably ancestral. Each molar consists of two laminae, separated by a deep internal fold which extends almost to the external margin. On little worn teeth each lamina shows, on the external side, a shallow furrow extending to about the middle of the tooth, but these furrows early become pits and then disappear with further wear, being preserved on not over a fourth of our specimens. ‘The fourth upper premolar consists of two laminae, but in this case, the separating fold is on the external side and extends nearly to the internal margin, so that this tooth appears to be reversed in its position in the jaw. As in the molars, there is, on the external side of either lamina, a furrow, the one in the anterior lamina shallow and seldom seen, that in the posterior lamina deep and present in all but the most worn teeth. While the upper and lower molars appear so different they may be readily derived from such a tooth as the lower molar, as both have the two laminae and separating furrows in common. In the upper molars, however, the internal fold is prolonged until the external fold is merely indicated or lacking. On upper premolar 4, on the con- trary, it is the external fold which is prolonged. The fur- rows in the external portions of the laminae of the upper molars correspond to those on the internal portions of the same laminae of the lower teeth, reversed, as is typical of all teeth. Ameghino distinguished three species of Cephalomys, which are based primarily on size, the other characters which he gave being inconstant. We found these three and no others. UPPER PM. 4 LOWER PM. 4 TO M. 3 TO M. 3 C. arcidens 13-14 mm. 14-15 mm, C. plexus 9.5 mm. 10.5 mm. C,. prosus 8.5 mm. 9.5 mm. CEPHALOMYS ARCIDENS 189 Cephalomys arcidens Ameghino C. arcidens Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 494. This, the type species, is by far the commonest of the rodents, in fact of all the species in the Deseado, and we found forty-seven specimens on the Chico del Chubut River, west of Puerto Visser. In the species there is con- siderable variation in size for a rodent, but as there are intermediate specimens all the way between the extremes, and as the variation is mostly in the sizeof the fourth premolar, it does not seem proper to separ- ate the material into more than one species. In general, the form has relatively plump teeth, relatively heav- ier and thicker than in the other species. Usually the fourth premolar is but little larger than the molars, ie pe Leth lowempr molar molar suey decodu itein, this, character, ous premolar 4; B, a little worn mola 1; C, series about half worn down; a.l., anterior lamins; /.l., posterior Da 4 Sea led s lamina; 1.f., internal fold; e.f., external fold; p.g., fur- there Is ¢ onsiderable row in posterior lamina; x 4/T1. variation. ah h e fol 4 lowing measurements give the range of size on the upper jaws: Fig. 118. Right upper premolar, molar series x 4/1. SPECIMEN SPECIMEN AMEGHINO'S 3109 3099 TYPE A SMALL A LARGE [INDIVIDUAL INDIVIDUAL Upper premolar 4 to m. 3 12.5 mm, 13.5 mm. 13.5 mm. Upper premolar 4, length 3.5 mm. 4.5 mm. Each molar, length 3. mm. 3) mim. Each molar, width 2.75mm. 2) ain. 190 THE DESEADO FORMATION OF PATAGONIA The lower jaw is low, heavy and rather short, the posterior part of the ramus being very thin, while the portion carrying the teeth is thick and heavy. A strong ridge extends along the inner side from just behind molar 3 to the base of the symphysis. As in the upper dentition, there are smaller and larger forms. SPECIMEN SPECIMEN AMEGHINO’S 3089 3058 TYPE A SMALL A LARGE INDIVIDUAL INDIVIDUAL Lower premolar 4 to m. 3 14 mm. 15 mm. 14.5 mm. Lower incisor 1 to pm. 4 7+) gins 9 mm. 7.8 mm. Height of mandible under pm. 4 7) 9 esrimis 8 mm. 7) mms Length of deciduous pm. 4 5.5 mm. Cephalomys plexus Ameghino C. plexus Amegh., 1897, Bol Inst. Geog. Argen., t. 18, p. 494. In general, this species is similar to the foregoing, but is smaller in size and slenderer in proportions. Both the upper and lower fourth premolar tend to be considerably larger than Ls the molars. The species was ==" \ not nearly as abundant as C. ini, Ho. Richt paldlate dhowihk ore. ET CIdenS, | Occurring but | Srap am molar, molar series; external furrows appear as pits on molars 2 and 3, x 4/1. times in our collection. eae Fig. 121. Left mandible, external side, x 4/1. CEPHALOMYS PLEXUS I9I MEASUREMENTS SPECIMEN AMEGHINO'S 3091 TYPE Upper dentition, pm. 4 to m. 3 9. mm. 9.5 mm. Upper dentition, pm. 4, length 2.75 mm. Upper dentition, each molar length 2.) “mm. Upper dentition, each molar width 2.25 mm. The lower jaw is slender, the incisor being relatively both smaller and slenderer than in C. arcidens; the back part of the ramus light and thin, the coronoid process being a tiny spur, and the articular condyle of small size, and on a level with the teeth. MEASUREMENTS SPECIMEN AMEGHINO’S 3005 TYPE Lower dentition, pm. 4 to m. 3 TO. “mm: 10.5 mm. Lower dentition, in. 1 to pm. 4 6 mm. 6.5 mm. Lower dentition, pm. 4, length Lower dentition, each molar, length Lower dentition, each molar, width Height of mandible under pm. 4 Fig. 123. C. prosus, left upper premolar, molar series, x 4/I. Fig. 122. C. plexus, left lower premolar, pms molar series; A, of young individual; B, of old individual; znt., internal side; ext., Fig. 124. C.prosus, premolar 4 external side, x4/T. and molar 2, x 4/1. Cephalomys prosus Ameghino C. prosus Amegh., 1902, Bol. Acad. Nac. Cienc. Cordoba, t. 17, p. 37. This is the tiniest species of the genus, and least fre- quently found, probably because on account of the small size it was more frequently destroyed before burial, and also because it is hard to find such tiny specimens; so that 192 THE DESEADO FORMATION OF PATAGONIA the sixteen which we found would hardly represent the real proportion of the species in the fauna. The jaws are not only small, but also slender and deli- cately built, with the premolar about the same size or slightly larger than the molars. The drawings represent the proportions accurately so I will give but a few measure- ments. SPECIMEN AMEGHINO’S 3009 TYPE Upper premolar 4 to molar 3 8.5 mm, Lower premolar 4 to molar 3 9.5 mm, Scotamys gen. nov. A lower jaw, with premolar 4 and molars 1 and 2, from the Deseado beds on the Chico del Chubut River, west of Puerto Visser, indicates a genus of hystricomorph rodents not previously reported. The lower molars suggest those of Perimys, but premolar 4 is similar to that of Scotaeumys from the Santa Cruz. Scotamys differs, however, from Scotaeumys, in that its molars do not have the third lobe found in the Santa Cruz genus. I have, therefore, made a new genus which appears to be ancestral to Scotaeumys. Scotamys antiquus sp. nov. This, the type species of the above genus, is based on specimen 3063, a lower jaw with the incisor, premolar 4 and the first two molars. The incisor is fairly large and heavy, the anterior face slightly convex, and the anterio- posterior diameter greater than the transverse diameter. Premolar 4 hasa deep external fold, dividing the crown into an anterior and posterior lamina, the former being then subdivided by another external fold, making the tooth three-lobed. Just internal to the median fold is a tiny pit, apparently the last vestige of an internal fold. Each molar consists Fig. 125. Lower premolar 4 —molar 2, x 4/I. SCOTAMYS 193 of two laminae separated by a deep external fold, around the inner end of which the laminae are connected by a narrow bar. In the present condition of wear there is no indication of secondary furrows. The premolar is smaller than the molars. MEASUREMENTS SPECIMEN 3063 Lower dentition, in. f to pm. 4 8 mm, Lower dentition, premolar 4 length 3 mm., width 2.5 mm. Lower dentition, molar 1 length 2.5 mm., width 2.5 mm. Lower dentition, molar 2, length 75 mm., width 3 mm, Height of mandible under pm. 4 5.5 mm. Fig. 126. Left mandible external side, x 4/1. Litodontomys gen. nov. One set of lower teeth found by the Amherst party shows a simplicity of pattern found in no other genus of South America; and this is, therefore, named Litodontomys. The teeth are brachydont, the premolar and the molars each being divided into two laminae by an external and an internal fold, the distinctive generic feature being in that this fold is narrowest at the margin of the tooth and expands internally. In connection with the expanded folds, the ends of the laminae are curved toward each other, so that in a worn specimen they would meet on the margins of the tooth, and leave the folds to appear as pits. No indication of a furrow is evident on either lamina. 13 194 THE DESEADO FORMATION OF PATAGONIA Litodontomys chubutensis sp. nov. The type is number 3086 of the Amherst collection, from the Deseado beds on the Chico del Chubut River, west of Puerto Visser, and consists of the lower premolar-molar series. Premolar 4 is elongated, the Ee. 27, SRN oes renee ees Han eerlOt lamina being consider- ably longer than it is wide, whereas the laminae of the other teeth are wider than they are long. The following measurements with the figure give the specific details. Lower dentition, premolar 4, to molar 3 10.5 mm, Lower dentition, premolar 4, length 3.5 mm Lower dentition, molar 1, length 2. mm Lower dentition, molar 2, length 2.5 mm Lower dentition, molar 3, length 2.5 mm Lower dentition, width of molars 2. mm ERETHIZONTIDAE Asteromys Ameghino Asteromys Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 495. The genus contains small forms, with brachydont teeth. The upper molars consist of two laminae, separated by an internal and an external fold, and each lamina having, on the internal half, a deep furrow, which is but little shallower than the median fold; so that the outer side shows three furrows, folds, or pits, more or less completely separating four lobes; while on the inner side of the tooth there are but two lobes. On the lower teeth the external median fold is deep, while the internal median fold is shallower, usually appearing as a pit. Both the anterior and posterior laminae are subdivided by wide internal furrows which extend to the median line. These characters associate the genus with Acaremys of the Santa Cruz, from which genus it is not easy to separate ASTEROMYS 195 Asteromys; but as we know only the teeth from the Deseado beds, it is probable that, when the skull is found, larger differences will be recognized. Asteromys appears to be the direct ancestor to Acaremys. The species are all tiny, the following three being dis- tinguished by Ameghino. LENGTH OF LOWER MOLAR SERIES A. punctus (Bol. Inst. Geog. Argen., 1897, t. 18, p. 495) I2 mm. A. annectens (Bol. Acad. Nac. Cienc. Cordoba, 1902, t. 17, p. 37) It mm, A. prospicuus (Bol. Inst. Geog. Argen., 1897, t. 18, p. 495) each molar 1.6 to 1.8 mm. Of these three we found only the last. Asteromys prospicuus Ameghino A. prospicuus Amegh. loc. cit. above. The species is rare, only three specimens turning up in our collections. The upper molars are as described in Fig. 128. Right upper premolar 4— Fig. 129. Left lower molar 3, x 4/I. molar 2, x 4/I. the generic discussion, but premolar 4 is simpler than the molars, the posterior lamina being small and without any sort of furrow. In the upper molars the anterior lamina is larger than the posterior, and the anterior furrow wider than the posterior. The following measurements, with the figures, indicate the character of the species. Upper dentition, premolar 4 to molar 3 8.75 mm. Upper dentition, premolar 4, length 2. mm. Upper dentition, each molar, length 222 ins Upper dentition, each molar, width 2: mm. Lower dentition, molar 2, length 2-75, mins Lower dentition, molar 2, width 1.75 mm. 196 THE DESEADO FORMATION OF PATAGONIA Eosteiromys Ameghino Eosteiromys Amegh., 1902, Bol. Acad. Nac. Cienc., Cordoba, t. 17, p. 10. The genus was established by Ameghino for forms similar to Steiromys of the Santa Cruz, but antedating that time. I confess I can see but little difference between Steiromys and Eosteiromys, but the latter is as yet known only from isolated teeth and as in general it would be expected that there should be a generic difference, we may let this genus stand representing rather a prophecy than the facts as yet known. The upper teeth are brachydont, the crown being on the same general plan as in the foregoing genus, 7. ¢., it is divided into an anterior and posterior lamina by a deep external median fold and by a shorter oblique internal me- dian fold. The anterior lamina is subdivided by two ex- ternal furrows, a lesser anterior and a larger posterior; while the posterior lamna is subdivided by a single external furrow; so that this tooth has four folds, furrows, or pits on the external side separating five lobes; while on the inner side there is but the one oblique fold separating two lobes. Eosteiromys medianus Ameghino ? E. medianus Amegh., 1902, Anal. Mus. Nac. Buenos Aires, ser. 3, t. 2, p. 129. The genus is based on a single, though entirely characteristic, upper molar. We found just one tooth of the species, also an upper molar. It is described above, under the genus. ‘The measurements are: Upper Big. 13) ees “molar 2, length. 4 mm., width 5 mim, CHAPTER SGlv. EDENTATA THE scarcity of edentates in the Deseado beds is in striking contrast to their abundance in the Santa Cruz formation. Whereas in this latter horizon over half of the finds are edentates, in the Deseado only eight per cent. of the total collection belong to this group, and this is doubt- less a larger proportion than these animals represented in the fauna; for the hundreds of small plates in a carapace, when scattered greatly, increase the chance that some part of an individual will be found, and most of the eight per cent. of finds are single plates. Most of the plates found represent armadilloes, our collection containing but one plate of a glyptodont, and no gravigrades. Ameghino’s collections present about the same relations, but in the repeated trips he found a few more traces of glyptodons and a very few gravigrades. This scarcity of edentates can not be taken to mean that they were not developed, for they are a peculiarly South American group, and as they were developing somewhere into their great complexity, I take it to mean that the climatic conditions were unfavorable in this particular section, As noted above, all previous finds have been isolated plates. We were fortunate enough to find one specimen consisting of a carapace with ten rows of movable plates in place, and parts of four rows of the pelvic buckler to- gether with over fifty isolated plates. A second specimen had some fifty associated plates which were mostly from the pelvic buckler. Dasypoda The representatives of this group are so poorly known in the Deseado beds that Ameghino has, in general, used 198 THE DESEADO FORMATION OF PATAGONIA the generic names of the Santa Cruz for their description, and, so far as known, they are little differentiated from those genera. There is as yet no material which shows the association of skeletal parts with the carapaces. There- fore, in this paper, comparisons are made wholly on the carapace, with the expectation that the skeleton, when found, will correspond. The Deseado species are but little less specialized than the Santa Cruz, the carapace consisting of movable over- lapping bands of plates both in the anterior and body portions, while over the pelvic region the plates are fixed, do not overlap, and form a pelvic buckler. Ameghino has described a considerable number of genera based on isolated plates, to which I refer later. The chief genera which occur in these beds are also found in the Santa Cruz, and the distinguishing features are as follows: CEPHALIC SHIELD | MOVABLE PLATES | PELVIC BUCKLER | ORNAMENTATION Proeutatus Plates thin, coarsely|Plates thick, } over-|8 + probably 10) ‘‘Flask”’ figure pitted lapped rows Prozaedius Plates thin, finely|14 bands, thin, 4/8 rows \3 long ridges, pitted overlapped median ridge nar- row Stenotatus Plates thick,coarsely|Plates thick and/1r rows l3 long ridges, all pitted wide subequal Proeuphractus + overlapped No buckler Peltephilus 19 or 21 Plates 2 or 4;/Wide and thin 2-4)Buckler Large shallow pits horns wide pits Proeutatus Ameghino Eutatus Amegh., in part, 1887, Bol. Mus. La Plata, t. 1, p. 25. Proeutatus Amegh., 1891, Revista Argen. d. Hist. Nat., t. I, p. 327. Thoracotherium Mercetat, 1891, Revista Mus. La Plata, t. 2, p. 42. Eutatus Lydekker, in part, 1894, Anal. Mus. La Plata, t. 3, p. 62. Proeutatus Scott, 1903-5, Reports Princeton Patagonian Exp., vol. 5, p. 40. This is the most frequently occurring genus in the Deseado, but is as yet represented only by isolated plates. PROEUTATUS 199 The genus is distinguished by thick, relatively long and narrow, movable plates, each overlapped by about a third of its length. The plates of the pelvic buckler are shorter and thicker, the exposed surface of each being ornamented by a figure compared by Ameghino to a flask (see fig. 131), which figure is more distinct on the rear, fading away toward the front. On the plates of the pelvic buckler this figure is more accentuated, and from it, on either side, radiate two furrows dividing the surface into several (4 to 5) areas. The entire surface of each plate is irregularly punctate. Proeutatus lagenaformis Ameghino P. sp? Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 660. P. lagenaformis Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 507. On the Chico del Chubut River, west of Puerto Visser, we found nine specimens of this S29 o5) all fragmentary, though one consists of over fifty more or less broken plates, mostly from the pelvic buckler. This is the only species of the genus from the Deseado, and corresponds to the description above. A movable Fi ue P plate generally measures about 28 Fig. 131. A, movable plate; B and mm. long by 10 mm. wide, and has tralaze "PY" aa es four large piliferous pits on the posterior margin. A plate of the pelvic buckler varies greatly in size, but is always thick and has two to eight piliferous holes on the posterior margin. A typical plate measures 20 mm. long by 10 mm. wide. Prozaedius Ameghino Zaedius Amegh., in part, 1889, Act. Acad. Nac. Cordoba, t. 5, p. 867. Prozaedius Amegh., 1891, Revista Argen. Hist. Nat., t. I, p. 327. Dasypus Lydekker, in part, 1894, Anal. Mus. La Plata, t. 3, p. 55. Prozaedius Scott, 1903-5, Reports Princeton Patagonian Exp., vol. 5, p. 69. Of this little genus, which is so strikingly like the living Zaedius, we found a carapace with ten rows of movable 200 THE DESEADO FORMATION OF PATAGONIA plates in place, parts of four rows of fixed plates from the pelvic buckler, and some caudal vertebrae. ‘The genus is distinguished by its thin plates, there being fourteen bands of movable plates, and eight rows in the pelvic buckler. The movable plates are narrow, each overlapped about a fourth of its length, and have a faint ornamentation, with no piliferous pits except on the posterior margin. ‘The fixed plates are similar, except that they are shorter, and have the ornamentation more accentuated, with radial grooves. Ameghino has described three species as follows: P. impressus, sculpture little accentuated, post. piliferic pits rudimentary, P. planus, sculpture more accentuated, post. piliferic pits lacking. P. tenuissimus, very small. In my specimen, the two anterior rows of movable plates lack the marginal piliferous pits, on the next two rows they are rudimentary (which is also true of the lateral plates even further back), while on the bulk of the movable plates and on those of the pelvic buckler there are two, three or four good-sized piliferous pits on the rear. I can therefore recognize but two species, P. impressus and P. tenuissimus. Prozaedius impressus Ameghino P. impressus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 508. P. planus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 509. Our specimen was found on the Chico del Chubut River, west of Puerto Visser, and preserves over two hundred plates, and eight caudal vertebrae. The anterior rows of plates of the carapace consist of thin plates overlapping about a fourth their length. Just behind the overlap, there is, on each, a group of small punctations, and the exposed part of the surface is divided by two shallow furrows, making three more or less equal ridges which die out toward the rear, leaving the posterior part of the plate plain. These most anterior plates are bent to one side and have no piliferous pits on the rear margin. ‘The plates of the third and fourth rows are not bent, and have the sculpture more distinct, the extreme lateral plates having no piliferous PROZAEDIUS IMPRESSUS 201 Fig. 132. Portion of carapace—natural size; unshaded plates are from cast; a and 6 plates from pelvic buckler, 202 THE DESEADO FORMATION OF PATAGONIA pits, the median lateral plates with rudimentary piliferous pits, and the dorsal ones with well marked posterior pits. In each succeding row toward the rear, the plates are more distinctly ornamented and have larger posterior marginal pits. I have no marginal plates. The plates of the pelvic buckler do not overlap, are shorter, have a very distinct figure, and, in addition to the longitudinal furrows, have a couple of radial furrows on either side, which divide the plate into four or five areas (see fig. 132 a and b). The caudal vertebrae are short and thick, indicating a short tail. I found no plates which would indicate a caudal shield, which coincides. with the experience among the Santa Cruz specimens. The figures are to scale and give most of the measurements. There are ten rows of movable plates, probably two to three rows lacking. There are twenty + plates to a row. A typical movable plate measures 17 mm. long by 6 mm. wide. There were at least four rows in the pelvic buckler, probably eight as in the Santa Cruz. A typical fixed plate measures 10 mm. long by 5 mm. wide. Prozaedius tenuissimus Ameghino P. tenuissimus Amegh., 1902, Bol. Acad. Nac. Cienc. Cordoba, t. 17, p. 66. This species is characterized by Ameghino on account of its small size. The movable plates have two furrows which converge toward the front, and between which is a median crest. In the furrows are two rows of perforations. A movable plate measures 9 mm. long by 4 mm. wide. Stenotatus Ameghino Euphractus Ameghino, in part, 1887, Bol. Mus. La Plata, t. 1, p.26 of separate. Dasypus Amegh., in part, 1889, Act. Acad. Nac. Cienc. Cordoba, t. 5, p. 864. Stenotatus Amegh., 1891, Revista Argen. Hist. Nat., t. 1, p. 253. Dasypus Lydekker, 1894, Anal. Mus. La Plata, t. 3, p. 55. Prodasypus Amegh., 1894, Bol. Acad. Nac. Cienc. Cordoba, t. 13, p. 172 of separate. Stenotatus Scott, 1903-5 Princeton Patagonian Exped., vol. 5, p. 80. The genus is very like Prozaedius but differs in having thicker and wider movable plates, in having more rows of PROEUPHRACTUS 203 plates in the pelvic buckler (11), and in details throughout the skeleton. We found no representatives of the genus, but Ameghino has described a species (no figure), S. (Prodasypus) ornatus* based on isolated plates. A moy- able plate measures 18 mm. long by 6-7 mm. wide, while a fixed plate measures 9 mm. long, by 6-7 mm. wide. Proeuphractus Ameghino Proeuphractus Amegh., 1886, Bol. Acad. Nac. Cienc. Cordoba, t. 9, p. 208. This genus is seldom found, but is distinguished by Ame- ghino by the absence of a pelvic buckler, all the plates of the crapace being movable. From the Deseado beds, Ameghino describes two species, P. setiger and P. laevis, both based on isolated plates; the former distinguished by having no pilif- erous perforation in the furrows surrounding the central figure, and with well-developed pitson the posterior margin; while the latter has small piliferous perforations in the fur- rows and only rudimentary ones on the posterior margin. These features do not seem to me to distinguish species. In addition to the foregoing, Ameghino has made a series of genera and species,t Archaeutatus, Amblytatus, Isutaetus, Sadypus, Hemiutatus, Anutaetus, all based on isolated plates, and distinguished by variations in the central figure and the piliferous pits. I am unable to find a satisfactory basis for distinguishing the genera or species, and feel that, until more complete material is known, it is impossible to say which are valid genera or species. Peltephilus Ameghino Peltephilus Amegh., 1887, Bol. Mus. La Plata, t. 1, p. 25 of separate. Cochlops Amegh., in part, 1889, Act. Acad. Nac. Cienc. Cordoba, t. 5, p. 792. Gephyranodon Amegh., 1891, Revista Argen., Hist. Nat., t. 1, p. 119. ? Anatiosodon Amegh., 1891, Revista Argen. Hist. Nat., t. 1, p. 327. Peltephilus Scott, 1903-5, Princeton Patagonian Exped., vol. 5, p. 88. While rare, this genus is well known from the Santa Cruz, and is characterized by the curious development of * Bol. Inst. Geog. Argen., t. 18, p. 508, 1897. + Bol. Acad. Nac. Cienc. Cordoba, t. 17, p. 56-66, 1902, no figures. 204 THE DESEADO FORMATION OF PATAGONIA the head shield, which consists of nineteen or twenty-one definitely arranged head plates, the anterior ones being developed into horn-like projections. The plates of the carapace are wide, thin, and unique in each having two to four wide shallow pits on the exposed surface. We found the genus rare, only two isolated plates turning up. From the Deseado material Ameghino has made three species: P. protervus, of very large size; P. undulatus, of moderate size, with the median figure accentuated and ending in two pits and with piliferous depressions on the margin; and P. depressus, of the same size as the foregoing, with a faint central figure, often four pits on the exposed surface and no piliferous pits on the margin. We found but one species, one plate of which combines characters of both the last two as described, so that I feel that there should be but two species, P. protervus and P. undulatus. Peltephilus undulatus Ameghino P. undulatus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 509. P. depressus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 510. One of the plates we found has the rough surface, obscure figure, two pits on the median part of the surface, and marginal piliferous pits, of which the first two features are characters of P. undulatus, the last is the feature of P. depressus, so | have combined the two species. A second plate does not Fig. 133. Two movable plates—natural size, have the marginal, pits but is.otherwise the same. I expect considerable variation in the pattern on plates from different regions of the carapace. Peltephilus protervus Ameghino P. protervus, Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 509. This species, of which we found no representative, is very large. The plates of the type have two pits on the PALAEOPELTIS 205 anterior part of the exposed surface and none on the margin. A movable plate measures 41 mm. long by 22 mm. wide. One of the horn-like plates from the cephalic shield is 35 mm. long, by 30 mm. wide, and has a height of 44 mm. GLYPTODONTIA This suborder is most sparingly represented, apparently on account of unfavorable habitat. Ameghino has de- scribed a few fragments of the carapaces of these forms, making the genera, Palaeopeltis, and Glypiatelus, both pre-Santa Cruz genera. Palaeopeltis Ameghino Palaeopeltis Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 659. The basis of this genus is a few plates of a glyptodon- like animal of considerable size, but the plates are without ornamentation. This form Ameghino considers inter- mediate between glyptodonts and armadilloes. I feel that there is too little of the skeleton known to justify this conclusion, especially as glyptodonts of a considerably higher grade of specialization are contemporaries of this form. Fig. 134. P.inornatus: a single plate—natural size 206 THE DESEADO FORMATION OF PATAGONIA Palaeopeltis inornatus Ameghino P. inornatus Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 659. P. inornatus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 506. The species is founded on four plates which are without ornamentation, and externally smooth except for numerous vascular perforations. They are of considerable size and entirely characteristic. The one such plate which we found is shown in fig. 134. Glyptatelus Ameghino Glyptatelus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 507. The plates of the carapace are similar to those of Pal- aeohoplophorus, the O-figure being, however, nearer the rear of each plate, and the number of radial furrows being smaller, usually six. We found no specimens of this inter- esting form. Ameghino has made two species, G. tatusinus and G. malaspinensis. Glyptatelus tatusinus Ameghino G. tatusinus, Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 507. I reproduce Ameghino’s figure of this species which shows all that is known of the form. Fig. 135. Four plates—natural size, after Ameghino. GLYPTATELUS 207 Glyptatelus malaspinensis Ameghino G. malaspinensis Amegh., 1902, Bol. Acad. Nac. Cienc., Cordoba, t. 17, p. 50. This species is described (no figure) as about the same size as the preceding, but with subordinate figures in the central O-figure, and also outside of it. A dorsal plate measures 26 mm. long by 20 mm. wide. GRAVIGRADA Remains of this suborder are almost as rare as those of the glyptodonts, and apparently for the same reason, unfavorable habitat. We found no remains of this group, but Ameghino has described a skull and some teeth as belonging to this group; so, in order to present a complete view of the Deseado fauna, I give a digest of his descrip- tions. Hapalops antistis Ameghino H. antistis Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 505. The species is based on a skull, not figured, of which Ameghino says: the size is small, the molars are compressed from front to back, and gives the following measurements: Length of cranium from front of max. to occ. condyles 140 mm, Length of four post. molars 27 mm. Distance from front of max. to back of last molar 48 mm. Octodontotherium Ameghino Octodontotherium Amegh., 1895, Bol. Inst. Geog. Argen., t. 5, p. 656. The genus is based on isolated teeth, each a mass of dentine surrounded by a thin layer of cement. The an- terior tooth of the upper jaw is caniniform, the first molar ovoid in section, the last molar is bilobed, corresponding to Pseudolestodon. The first tooth of the lower jaw is also caniniform, but is two-faced as a result of wear. The intermediate upper and lower molars are rectangular prisms resembling those of Chlamdotherium. 208 THE DESEADO FORMATION OF PATAGONIA Octodontotherium grandis Ameghino O. grandis Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 656. O. grandis Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 505. In addition to the above, Ameghino simply gives the following measurements: First upper tooth, ant.-post. diam. 20 mm., trans. diam. 13 mm., height 80 mm. First lower tooth, ant.-post. diam. 21 mm., trans. diam. 16 mm., height 80 mm. Last lower tooth, ant.-post. diam. 28 mm., trans. diam. of ant. lobe 18 mm. Last lower tooth, trans. diam. of post. lobe 16 mm., median diam. 7 mm. Fig. 136. A, lower molar, side view—natural size; B, lower molar, cross section—natural size; C, upper molar, cross section—natural size, after Ameghino. Octodontotherium crassidens Ameghino O. crassidens Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 505. This second species is based on isolated teeth of larger size than the preceding, with measurements as follows: Upper molar, ant.-post. diam. 26 mm., trans. diam. 18 mm. Lower molar, ant.-post. diam., 26 mm., trans. diam. of ant. lobe 21 mm., trans. diam. of post. lobe 16 mm. ORPHODON 209 Orphodon Ameghino Orphodon Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 658. Orphodon Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 504. The teeth of this type are a mass of dentine, each sur- rounded by a thin layer of cement, and each tooth subcy- lindrical in section, with the crown worn to two apposed oblique planes. The genus resembles Ortotherium. Fig. 137. Type—natural size, after Ameghino. Orphodon hapaloides Ameghino O. hapaloides Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 658. O. hapaloides Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 505. In addition to the above, Ameghino gives a figure, here reproduced, and the following measurements: ‘Tooth, greatest diam. 12 mm., lesser diam., 10 mm. 14 CHAPTER’ XV MARSUPIALIA IN ouR collection, the marsupials are represented, un- fortunately, by but a few specimens; though this Deseado fauna included, as is shown by the fragmentary remains, a wide range of forms from Pilchenia, the size of a mouse, up to the bear-sized Proborhyaena. ‘The small forms were probably insectivorous, while the larger forms took the place of the carnivors, the absence of true Carnivora being one of the striking features of the fauna of South America during earlier Tertiary times. The treatment of these forms has been as varied as their sizes. Ameghino, with his idea that the Casamayor and Deseado beds were Cretaceous in age, groups the larger forms as a suborder, Sparassodonta, and considers them ancestral to the Creodonta; while the small forms make up his Sarcobora which he considered ancestral on one side to the rodents, on the other to the diprotodont marsupials. Sinclair, after showing the marked similarity of the Spar- assodonta to the polyprotodont marsupials, especially the genus Thylacynus, abandons that term and puts them in the family Thylacynidae along with the Australian forms; the Microbiotheridae he finds similar to opossums and puts in the family Didelphidae; while the remaining small diprotodont forms he associates with Caenolestes, and using Ameghino’s families as subfamilies makes three divisions of the family, Palaeothentinae, Garzoninae, and A bderitinae. Matthew finds the sparassodonts to be true marsupials, and without phylogenetic relationship with the creodonts. Gregory diagrams the sparassodonts as coming from gener- alized didelphids and derives them from the same line as the Australian polyprotodonts; while the small caenoles- MARSUPIALIA 211 toids represent a line of descent from some still earlier generalized polyprotodonts and a separate stem from the Australian diprotodonts. Sinclair has had the most complete material on which to work, and with his general grouping I have come to agree. This recognizes three divisions of South American Marsupials, the Didelphidae, representatives of which have not yet been found in the Deseado, though occurring in both the earlier and later formations; the Caenolestidae represented today by Caenolestes, the only survivor of the South American diprotodonts; and the Borhyaenidae (=Thylacynidae of Sinclair this name having been used to indicate a much nearer relationship to the Australian Thy- lacynus than I feel is warranted), which includes a large range of medium to large sized animals ranging from the Casamayor formation throught the Santa Cruz beds. The locality from which these marsupials emigrated to South America and the time of their arrival is not yet agreed upon, and can not be settled until much more com- plete material is discovered in the Casamayor formation. I feel, however, that the three groups were separate when they entered South America. Borhyaenidae Ameghino has grouped in this family a considerable number of genera of powerful, wolf-like carnivorous marsupials, characterized by a dental formula **77",* heavy heads, short limbs with usually five semidigitigrade toes. The genera are mostly distinguished by the relative development of the protocone on the upper molars and the * There is a discussion as to the homologies of the premolars of marsupials and placental mammals, the one proposition being that marsupials have three premolars and four molars, the other that they have four premolars and three molars as in placentals. The evidence is not conclusive as to either proposi- tion, but in this paper I have designated these teeth along the latter line of thought. 212 THE DESEADO FORMATION OF PATAGONIA talonid on the lower ones. Figure 138 gives a typical mar- supial upper molar 2 and a lower molar 2 to show the sense in which these terms are used. The Santa Cruz genera are the best known and IJ therefore use them as a basis for comparison with the less known Deseado forms, of which we found but the one genus Pharsophorus at all abundant. Jn addition to this, Ameghino has reported a gigantic form designated Proborhyaena. The following table indicates the relationships of the best known genera. TALONID ON AGE FORMULA| PROTOCONE | UPPER MOLAR | LowER Mo- | SYMPHYSIS 3 LAR 3 Cladosictis Santa Cruz|_4 1 4 3 jon pm. 4—m. 3|Protocone Small basin |Ligamentous SAS Paracone vesti-| with one gal post. cusp Metacone Ant. ext. style Amphiprovivvera Santa Cruz) 4 ! 4 3 jon pm. 4—m. 3|Protocone Basin —_with|Ligamentous 3143 Paracone two post. Ant, ext. style cusps Prothylacynus Santa Cruz) 4 1 4 3} onpm.4m.1|Protocone ves-|Small basin|Fused 3143 tigal with one Metacone post. cusp Borhyaena Santa Cruz| 3 1 4 3 |vestical Paracone No basin Fused 32143 Ant. ext. style |One post.cusp Pharsophorus Deseado I 4 3 |vestigal Protocone ves-|Very small |Ligamentous 143 tigal No basin Paracone One post.cusp Ant. ext. style Proborhyaena Deseado i? Fused 143 From the foregoing, it will appear that Pharsophorus approaches Borhyaena and Prothylacynus in the structure of its upper molars, being, however, nearer to the former, and the same is true of the structure of the talonid; but Pharsophorus differs markedly from both in retaining the metaconid as a small cusp on the side of the protoconid on all of the lower molars; also in the extremely small size PHARSOPHORUS 213 of the talonid of the lower molars, which in Pharsophorus have no basin and consist of a single cusp; and, lastly, in the symphysis of the lower jaws being ligamentous, whereas in the two preceding genera, it is fused. Pharsophorus is probably ancestral to Borhyaena. In the case of Probor- hyaena, only a mandible, with the canine and premolars 3 and 4 intact, has been found. The fourth premolar is more reduced than in other genera, but, until more teeth are known, its affinities can not be at all closely determined. SL Um. Lim. Fig. 138. Diagram ofa generalized upper molar, U.m., and a lower molar, L.m., of Borhynidae; a.s.,ant. style; hid., hypoconulid; mt., metacone; mid., metaconid; pa., paracone; pad., paraconid; pr., protocone; prd., protoconid; td., talonid. Pharsophorus Ameghino Pharspohorus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 502. The genus was founded on a lower jaw with premolar 3 to molar 3 in position. We found beside the above an upper jaw with premolar 3, and molars 2 and 3 complete while premolar 4 and molar 1 are more or less fragmentary ; from which the following generic characters may be made out. ‘The incisors are tiny; the canine very large, equal to that of Borhyaena; the upper and lower premolars pro- gressively smaller from front to back. Upper premolar 3 is a simple two-rooted tooth, the crown consisting of a single blunt central cusp. On the upper molars the proto- cone is not developed as a cusp, though the third inner root 214 THE DESEADO FORMATION OF PATAGONIA is present and carries a rounded shelf. The paracone is the chief cusp, and is developed as a high central pointed denticle. The metacone is not developed as a cusp, but is represented by a long slanting ridge to the rear, the apex of which has been fused to the paracone. ‘The last upper molar is better developed than in most Santa Cruz genera, consisting of a high median cusp, the paracone; a small anterior cusp, the anterior external style; and a shelf-like posterior cusp, the protocone. Lower premolars I-3 are simple two-rooted teeth, each carrying a single cusp on the crown. ‘The fourth premolar carries a well marked paraconid in front, a large median protoconid on the rear of which is a tiny metaconulid; and a tiny talonid or heel which is without a basin and consists of a single tiny cusp. The molars are all of the same character as the last pre- molar. ‘The lower jaws are united by a ligamentous sym- physis. Ameghino distinguished four species, P. lacerans, P. tenax, P. mitis, and P. tenuis, in the order of their size. The last two are but little known but are quite certainly another genus. . Pharsophorus lacerans Ameghino P. lacerans Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 503. The species was founded on a lower jaw with the roots of the incisors, canine, and first two premolars, and with the remaining teeth intact. We did not find the species, : Tas Fig. 139. Left mandible—1/2 natural size, after Ameghino. PHARSOPHORUS 215 so I have reproduced Ameghino’s figure and give his measurements. Lower dentition, length incisor I to molar 3 114 mm. Lower dentition, length premolar 1 to molar 3 go mm, Lower dentition, height of mandible under pm. 4. 38 mm. Pharsophorus tenax Ameghino P. tenax Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 504. The species was based on a fourth premolar which was 10 mm. long as compared with 13 mm. in P. lacerans. We found on the Chico del Chubut, west of Puerto Visser, both an upper and lower jaw belonging to this species, which give us the knowledge of the upper den- tition for the genus. The species is distinguished by the smaller size, relatively heavy jaws, and plump teeth, indicating a heavier mv. m3. Fig. 140. Left upper jaw—t1/2 natural size; A, molars 3 and 4 from above; 4, molars from ex- ternal side. built animal than P. lacerans. The following measurements distinguish the species. Fig. 141. Right mandible—1/2 natural size. SPECIMEN 3192 Upper dentition, length premolar 1 to molar 3 76 mm. Upper dentition, premolar 3, length Upper dentition, molar 1, length Upper dentition, molar 2, length Upper dentition, molar 3, length 10.5 mm., width 6 mm. 11.5 mm., width 8.5 mm. é 12 mm. width g mm. .55mm., width 12 mm. 216 THE DESEADO FORMATION OF PATAGONIA SPECIMEN 3004 Lower dentition Distance from premolar 1 to molar 3 76 mm. Molar 1, length II mm., width 6 mm. Molar 2, length 13 mm., width 6 mm. Molar 3, length 13 mm., width 7 mm. Height of mandible under premolar 4 30 min. Notogale gen. nov. This genus is proposed for the species designated ? Phar- sophorus mitis by Ameghino (should probably include ?Phar- sophorus tenuis which however never having been figured and not found in our collection I cannot definitely place). While the upper teeth have the same general character as Pharsophorus, they are much more compressed and tren- chant. Upper molar 2 is similar to that of Pharasophorus in having the protocone reduced, and the metacone repre- sented by a long sloping ridge. ‘The last molar is also similar in having the antero-external style, the developed paracone, but the protocone is much less developed, appear- ing only as aridge. In the lower teeth, however, there is a marked difference, in that the metaconid is lacking on molars, while the talonid is developed into a small basin with a single cusp on the posterior margin. ‘This genus seems to be closest to the Santa Cruz genus Cladosictis. Notogale mitis Ameghino ? Pharsophorus mitis, 1897, Bol. Inst. Geog. Argen., t. 18, p. 504. Ameghino briefly describes, without a figure, a species in which premolar 4 and molar 3 together measure 14 mm. —9, I have assigned to this two specimens, the : {) one with pm. 2 incomplete, pm. 3 complete, ey Wis! and m. 2 also complete. These teeth meas- ural size. ure the same as Ameghino’s and I think are the same. ‘There is also a fragment of the upper jaw with molars 2 and 3, though imperfect. From these it appears NOTOGALE 217 that we have to do with an animal not only smaller than the preceding, but on much slenderer lines. The following are the measurements of the two specimens. SPECIMEN 3117 Upper dentition, molar 2, length 8 mm., width 6 mm. Upper dentition, molar 3, length 2 mm., width 6 mm. SPECIMEN 3060 Lower dentition, premolar 3, length 6 mm., width 2.5 mm. Lower dentition, molar 2, length 7 mm., width 4 mm. mz pm2 3 wy Lis aa Fig. 143. Left mandible—natural size. Notogale tenuis Ameghino ? Pharsophorus tenuis Amegh., 1897, Bol. Inst. Geog., Argen., t. 18, p. 504. This species was founded by Ameghino on a single lower premolar 3 which is 3 mm. in length. No further descrip- tion is given and no figure. Proborhyaena Ameghino Proborhyaena Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 501. The genus is founded on a large lower jaw carrying the canine and premolars 3 and 4 and roots or alveoli for the other teeth. It is the largest carnivor recorded from Patagonia, and as large as a small bear. It is not possible 218 THE DESEADO FORMATION OF PATAGONIA to place its exact relationships, for the most essential teeth are wanting, but it is certainly a distinct genus as indicated by the reduced size of premolar 4 and the plump character of the teeth. Proborhyaena gigantea Ameghino P. gigantea Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 501. We found no specimens of this great carnivor, so I am reproducing Ameghino’s figure and measurements. The Fig. 144. Right mandible—1/2 natural size, after Ameghino. heavy canine is channeled on the sides and much worn on the posterior face. Premolar 3 is a plump tooth, its crown consisting mostly of a single median cusp, but with a small heel behind, and, strikingly enough, premolar 4 is a smaller and simpler tooth with a single cusp. MEASUREMENTS Lower dentition, canine, antero-posterior diameter 30 mm. Lower dentition, canine, transverse diameter 20 mm. Lower dentition, premolar 1 to molar 3 745 mm. Lower dentition, height of mandible under pm. 4 60 mm, CAENOLESTIDAE 219 Proborhyaena antiqua Ameghino ? Borhyaena antiqua Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 655. Proborhyaena antiqua Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 502. This species is known only by a single canine 100 mm. long, of which but 15 mm. belongs to the crown. Its antero-posterior diameter is 14 mm., the transverse 12 mm. It seems to me very doubtful whether this is a valid species. Caenolestidae This family, based on the living genus Caenolestes, is represented in Tertiary times in Patagonia by three sub- divisions, Palaeothentinae, Garzoninae, and Abderitinae. While diprotodonts, as far as known, the family is in strong contrast to the Australian diprotodonts in that there is no sign of syndactylism in the pes. The American forms are characterized by four subequal upper incisors, a normal canine, the first three premolars vestigal, while the fourth is either normal or enlarged into a sectorial tooth. The three molars are progressively smaller from the front back. The first lower incisor is greatly enlarged and procumbrent, the remaining incisors, the canine, and the anterior pre- molars being vestigal though usually present. Premolar 4 is enlarged and sectorial in most genera, and the molars as in the upper jaw progressively smaller. For the practical purposes of this paper the subfamilies are distinguished as follows: Caenolestinae, lower pm. 4 not developed into a sectorial tooth. Palaeothentinae, lower pm. 4 is developed into a sectorial tooth. Abderitinae, lower pm. 4 is developed into a sectorial tooth and striated. Palaeothentinae Sinclair. (=Epanorthidae Ameghino) This group or subfamily was established to hold several : : é; ? genera of tiny marsupials with the dental formula 77); the lower fourth premolar enlarged into a sectorial tooth; 220 THE DESEADO FORMATION OF PATAGONIA and the molars small and buno-lophodont. From the Deseado beds but one genus of this subdivision has been found, Palaeothentes, designated by Ameghino first Epan- orthus, then later Palaepanorthus, but as I can see no reason for distinguishing the Deseado species of the genus from those of the Santa Cruz, I have retained the name Palaeo- thentes. The genera of this subfamily are distinguished as follows: Lower THIRD PREMOLAR Palaeothentes 2-rooted, fairly large, equals pm. 4 in height. Pilchenia 2-rooted, moderate size nearly equals pm. 4 in height. Callomenus 2-rooted, small size much lower than pm. 4. Decastris, 1-rooted, vestigal. Palaeothentes (Moreno) Ameghino Palaeothentes Moreno, 1882, Patagonia, Resto de un Continente hoy sub- mergido, p. 22, (nomen nudum). Palaeothentes (Moreno) Ameghino, 1887, Enum. Sist. Espesies Mamif. Fos, Patagonia, p. 5. Epanorthus Ameghino, 1889, Act. Acad. Nac. Cienc. Cordoba, t. 6, p. 271. Epanorthus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 500. (nudum). Palaepanorthus Amegh., 1901, Anal. Soc. Cienc. Argen., t. 51, p. 77, (nomen). Palaepanorthus Amegh., 1902, Bol. Acad. Nac. Cienc. Cordoba, t. 18, p. 123. Palaepanorthus Amegh., 1903, Anal. Mus. Nac. Buenos Aires, t. 9, (ser. 3, t. 2) p. 239. Among the Santa Cruz specimens, this genus is distin- guished by having in the lower jaw the large first incisor, then five vestigal teeth, followed by a two-rooted, though somewhat reduced, third premolar, next the enlarged fourth premolar, making the sectorial tooth, and lastly three buno-lophodont molars. There is considerable confusion as to the use of the gen- eric name. Moreno designated the first specimen, Palaeo- thentes, without a description; then Ameghino used this term describing the species; later Ameghino thinking that the name Palaeothentes was the same as Palaeothentis proposed the name, Epanorthus, using this for the first description PALAEOTHENTES 220 of the Deseado species. Later, however, he changed this for Palaepanothus. As 1 can see no generic differences between the Deseado and Santa Cruz species, I shall follow Sinclair in using the generic term Palacothentes. Palaeothentes chubutensis Ameghino Epanorthus chubutensis Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 500. Palaepanorthus chubutensis Amegh., 1901, Anal. Soc. Cienc. Argen., t. 51, p. 77: Palaepanorthus chubutensis Amegh., 1902, Bol. Acad. Nac. Cienc. Cordoba, i) 18, p: 123. Palaepanorthus chubutensis Amegh., 1903, Anal. Mus. Nac. B. A., t. 9 (ser. 3, t. 2) p. 239. The species is founded on a tiny mandible with premolar 3-molar 3, on which the third premolar, while reduced, Fig. 145. Right mandible—z2 times natural size, after Ameghino. has two roots and reaches the height of the fourth premolar, being in about the same stage of development as the Santa Cruz species. As we found no specimens of this species I reproduce Ameghino’s figure and measurements. Lower dentition, premolar 3 to molar 3 19 mm. Lower dentition, height under premolar 4 12 mm. Pilchenia Ameghino Pilchenia Ameghino, 1903, Anal. Mus. Nac. Buenos Aires, ser. 3, t. 2, p. 128. Pilchenia Ameghino, 1904, Anal. Soc. Cienc. Rep. Argen., t. 58, p. 259. This genus was founded on a single lower molar which, in the light of the specimen we found, I take to be the third 222 THE DESEADO FORMATION OF PATAGONIA or last. Our specimen shows pm. 3 and 4 and the three molars. The third premolar is a small two-rooted tooth with a simple crown and no heel. Premolar 4 is an en- larged sectorial tooth, the anterior part consisting of two cusps, closely set near the median line, with an incipient cusp on the inner face of the large anterior cusp. The posterior part of this tooth is arranged as a typical talonid, with one internal and two external cusps on the margin of a shallow inclosed basin. On the rear of the tooth is a small crescent-like cingulum, which occurs in the same place on molars 1 and 2, but is lacking on molar 3. This is a characteristic feature of the genus. On the anterior part of the molars is developed a sort of trigonid of small size, and the cusps are indistinct. The posterior portion of each molar is a large talonid with a shallow basin surrounded by a low wall on which are three tiny cups (the entoconid, hypoconid, and hypoconulid). Pilchenia lucina Ameghino P. lucina Amegh., 1903, Anal. Mus. Nac. B. A., ser. 3, t. 2, p. 128. P. lucina Amegh., 1904, Anal. Soc. Cienc. Rep. Argen., t. 58, p. 259. In the Deseado beds, on the Chico del Chubut River, west of Puerto Visser, we found a single specimen of this Fig. 146. Left mandible with premolar 3 to molar 4—4 times natural size. species which agrees with the single tooth figured by Ameg- hino as the type, and which I interpret as molar 3. The description is given under the genus, the measurements are as follows: CALLOMENUS 223 SPECIMEN No. 3110 Lower dentition, distance from premolar 3 to molar 3 14 mm. Lower dentition, premolar 3, length 2 mm., width .75 mm. Lower dentition, premolar 4, length 5 mm., width 2.5 mm. Lower dentition, molar 1, length 3 mm., width 2 mine Lower dentition, molar 2, length 2.5 mm., width 2 mm. Lower dentition, molar 3, length 2 mm., width 1.75 mim. Lower dentition, height under pm. 4 5 mm. Callomenus Ameghino Callomenus Amegh., 1891, Neuvos Restos Mamif. Fos. Patagonia Austral, p. 20. Callomenus Sinclair, 1901-6 Princeton Patag. Expeditions, vol. 4, p. 434. This genus has not been previously reported from the Deseado beds, but we found a tiny lower jaw with three teeth to represent it. The genus is distinguished by pre- molar 3 being two-rooted, but so small as not to attain the height of premolar 4. Callomenus praecursor sp. nov. The type is specimen No. 3020, a fragmentary mandible with premolars 3 and 4 and molar 1 in place. Pm. 3 is Fig. 147. Left mandible with premolar 3 Fig. 148. Left mandible internal side—4 times to molar 2—4 times natural size. natural size. two-rooted, but so small as to be entirely overshadowed by the succeeding pm. 4, hardly reaching a half the height of that tooth. On the last premolar and the first molar, the cusps are arranged in a trigonid in front and a talonid behind, the cusps being joined by thick ridges, making two connecting crescents. 224 THE DESEADO FORMATION OF PATAGONIA MEASUREMENTS, SPECIMEN 3020 Lower dentition, premolar 3, length 1 mm. Lower dentition, premolar 4, length 5 mm., width 2 mm. Lower dentition, molar 1, length 4 mm., width 2 mm. Lower dentition, height under pm. 4 6.5 mm. Caenolestinae - e ; nes aya Le, maic > > r sues The subfamily is distinguished by the formula 7—<—, pm. 4 not being enlarged, and the lower molars being tuberculo-sectorial. In the Deseado formation this group is only represented by a single species, based on a single tooth found by Ameghino. Pseudhalmarhiphus guaraniticus Ameghino P. guaraniticus Amegh., 1903, Anal. Mus. Nac. Buenos Aires, ser. 3, t. 2, p. 83. Based on a single tooth, similar to those found in the Sanita Cruz, Abderitinae The subfamily is distinguished by the formula», the fourth premolar being enlarged into a sectorial tooth on the sides of which are vertical striae. The molars are buno-lophodont. The Deseado has yielded only a tiny form, designated Parabderites, which differs from the Santa Cruz genus Abderites in pm. 4, the same shape, by with few to no striae on its sides. Parabderites minusculus Ameghino P. minusculus Amegh., 1902, Bol. Acad. Nac. Cienc. Cordoba, t. 17, p. 43. The species as described by Ameghino is based on a lower jaw with pm. 3 to m. 3. The specific character is the lack of striae on pm. 4. No figure is given but the following measurements indicate the size. Lower dentition, premolar 3 to molar 3 g mm. Lower dentition, height of mandible under pm. 4 4 mm. CHAPTER Xv BIRDS In THE Deseado beds, birds occur in small numbers, Ameghino having described four species. The remains are generally found as isolated bones, and it 1s hard to as- sociate the separate finds one with another. Beside this there are very few birds of the early Tertiary so known, as to make separate bones indicate the family or generic relationships. In the overlying Patagonian beds, a considerable number of species have been found, mostly of penguin-like birds, the various genera and species being based on the tarso- metatarsus. On the upper surface of the Deseado, we found several bones of this penguin-like type, but in all cases they were washed out, so that I have considered them as having come from the Patagonian. However, we found eight specimens of birds in place in the Deseado, most of which are clearly land birds and belong to genera which are closely related to genera of the Santa Cruz, especially the two genera Phororhacus and Pelecyornis, and of sizes equal to the largest represen- tatives of the two genera. Phororhacus Ameghino Phororhacus Amegh., 1887, Bol. Mus. La Plata, t. 1, p. 24. Phororhacus Amegh., 1889, Act. Acad. Nac. Cienc. Cordoba, t. VI, p. 659. Phororhacus Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 10 of separate. This is a group of large land birds, comparable in size to the great moasof New Zealand which apparently arose, flour- ished, and died out in South America. In the Santa Cruz they were abundant, the best known form being P. zflatus, a bird some six feet high; while the largest, P. longissimus, 15 226 THE DESEADO FORMATION OF PATAGONIA had a head nearly twice as long and limb bones half again as large as this species; so that it represented a bird nine to ten feet high. Previously but one specimen of this type, a part of a mandible, has been found in the Deseado beds. We were fortunate enough to find the greater part of a femur, indicating a bird equal to the largest of those in the Santa Cruz. There are also toe bones of Phororachus of a size about the same as P. inflatus. A host of names, generic and specific, have been given to the individual bones of the birds of this type, but Ameghino, in studying the birds of the Santa Cruz, brought them all together under the single genus Phororhacus. (See Bol. Inst. Geog. Argen., 1895, t. 15.) Referring to the single bone in the Deseado, however, he gave it a new generic name Physornis, which differs from Phororhacus only in the lower jaw being more convex, but should stand until better material has been found to establish whether it differs enough to be entitled to generic independence. Physornis fortis Ameghino. P. fortis Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 576. Under this specific name Ameghino describes a part of the lower jaw 150 mm. long which he says equals in size Phoror- hacus longissimus, and differs only in the greater convexity of the mandible. Our specimen is a femur, apparently of the same bird, being of the type of Phororhacus and about the size of P. longissimus; so | have placed it in this species. This femur is of large size, moderate length, and has a shaft subcylindrical in section. The distal end is expanded and the condyles are flattened, the inner one being the wider, the outer condyle being narrower and the external margin projecting to make a high ridge. The pit on the posterior side of the shaft just above the condyles is unusually deep and of large size. On the anterior side there extends from either condyle a low marginal ridge which soon fades into PHYSORNIS FORTIS q Fig. 149. Right femur, back view—1/2 natural size. ba | 228 THE DESEADO FORMATION OF PATAGONIA the contour of the shaft. Between these ridges there is a wide shallow furrow which also loses itself above in the con- vex surface of the shaft. MEASUREMENTS Femur, least diam. of the shaft 58 mm. Femur, diameter across the condules 148 mm. Physornis sp.? Two phalanges of a size too small to belong to the above species represent a second smaller bird of this type, about equal in size to Phororhacus inflatus. I give a figure of one toe but would wait for more typical material before establishing a species. Fig. 3151. Loxornis Fig. 150. Proximal clivus, lower end of phalanx of Physornis tibio-tarsus, after Ame- sp?—natural size. ghino-—natural size. Loxornis Ameghino Loxornis Amegh., 1895, Bol. Inst. Geog, Argen., t. 15, p. 595. Another group of bones, which we found with consider- able frequency, have the same features as Pelecyornis of the Santa Cruz. Ameghino has described but the lower end of a tibio-tarsus which can be associated with these bones and to it gave the name Loxornis. 1 can not find LOXORNIS 229 much variation from Pelecyornis except that the coracoid is considerably shorter and wider, and there is a slight variation in the lower end of the tibio-tarsus. “These then are the bases of the generic name. Loxornis clivus Ameghino L. clivus Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 595. Under this name Ameghino has described the lower end of a tibio-tarsus, a figure of which I reproduce here. This is of a size to complete the tibio-tarsus which we found, lacking the lower end, and agrees in size with the other Fig. 152. Humerus— Fig. 153. Sternum, thin parts lack- Fig. 154. Coracoid— 1/2 natural size. ing—1/2 natural size. 1/2 natural size. bones which we found, so that I shall describe my material under this name. ‘The species is in size comparable to Pelecyornis tubulatus with which it agrees closely. We found the upper four-fifths of a tibio-tarsus, associa- ted with part of the fibula, the sternum, the humerus, and the coracoid; a second specimen consisting of a complete tarso-metatarsus, and fragments of the pelvis, vertebrae and wing bones; a third specimen consisting of part of the tibio-tarsus, and various fragments; a fourth consisting of a femur, and lastly two toes; all evidently representing one species, which in most respects is almost identical with Pelecyornis tubulatus. These all came from the Chico del Chubut, west of Puerto Visser. 230 THE DESEADO FORMATION OF PATAGONIA The humerus has a large head but is considerably flat- tened at the proximal end. ‘The internal side is deeply excavated, the shaft is slender and light as though the wing were quite reduced, though not so much as in Pelecyornis and not nearly as much as in Phororhacus. The sternum had a moderate keel but both this and body of the bone are very thin, so much so, that in my specimen, much is broken away, giving the figure the appearance of the bone being fenestrated, which was not the case. In general the sternum is similar to Pelecyornts. The coracoid is a decidedly stout bone, with a wide dis- tal end for articulation of the sternum. The proximal end has a long articular facet for the scapula. This bone is heavier than the corresponding one in Pelecyornis. The femur has a small rounded head on a short neck, the articular surface spreading over the entire proximal end of the bone. Thus the trochanter is abbreviated and does not rise above the top of the head. ‘The shaft is of considerable length and fairly heavy. The tibio-tarsus has a wide flaring end to receive the articulation of the femur. The bone is very long as in Pelecyornis. On the external side is a long ridge along which the fibula was attached by cartilage or by ligaments, but was not fused to the tibio-tarsus. The shaft is approxt- mately cylindrical in section and fairly heavy. ‘The distal end is missing, but if I have associated correctly the speci- men figured by Ameghino, the condyles are flattened, the inner being the flatter, and the outer rising in a narrow margin. Figure 157 shows a fibula which would have occupied the position indicated along the side of the tibio-tarsus and corresponds entirely with the same bone in Pelecyornis. The tarso-metatarsus is long and slender, almost exactly the counterpart of the same bone in Pelecyornis. The bone has a triangular upper end, with two shallow articular LOXORNIS CLIVUS 231 concavities, separated by a median spine. The shaft is rectangular in cross section, has a shallow depression on the anterior face extending from the upper end to below the middle of the shaft; while on the posterior surface is a Fig. 157. Fibula—1 /2 natural size; outline from impression in ma- trix. Fig. 155. Femur—1/2 natural size. Fig. 156. Tibio-tarsus —1/2 natural size; fib- Fig. 158. Tarso-met- ula indicated in out- atarsus, front view— line. 1/2 natural size. similar furrow, which is however bounded by a higher ridge on the external margin. The distal articular condyles are almost bilaterally symmetrical, the middle one being about half again as large as the two lateral ones. Just above the cleft between the condyles for digits III and IV there is a moderate sized perforation. 232 THE DESEADO FORMATION OF PATAGONIA Of the phalanges, I have two unguals which are narrow curved claws. These were not found in association with any of the foregoing bones, but correspond in size and general character to those of Pelecyornis, and so I consider them as belonging to this genus and species. Fig. 160. Femur of unknown bird—natural Fig. 150. Ungual pha- , eee, Si ctearp ras size; special No. 3217. lanx—1/2 natural size. Ameghino has suggested that the genus was related to ducks, but with the more complete material it seems, in general build, much closer to the aberrant land birds of the Tertiary of South America, Pelecyornis and Phororhacus; and I am not in position to say what their derivation may have been. Beside the above species there are several more or less complete but isolated bones indicating the presence of other and much smaller birds. I figure such a femur natural size. he HY ue ny ae PAH: ih et it any A rt TLAgh Bi ‘ a) FI ain Le Rita! 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