Orthaspidotherium, Ocepeia, Amphicyon major, Hyopsodus and Meniscotherium

Amphicyon major (Blainville 1841, MNHN F Sa844, Middle Miocene, 13mya) is a traditional large 'bear-dog". Here this specimen nests among the herbivorous condylarths, close to Hyopsodus, despite the sharp claws, as in Agriochoerus latifrons (below).

Hyopsodus lepticus (H. paulus type, Leidy 1870; Late Eocene, 56-45 mya; ~20 cm in length; AMNH 143783) was originally considered a condylarth or a perissodactyl, an odd-toed ungulate, despite having a five-clawed manus and a four-clawed pes. Three molars are present.

Ocepeia, Meniscotherium and Orthaspidotherium compared

Meniscotherium tapiacitum (Cope 1874; Williamson and Lucas 1992; Middle Eocene 54-38 mya; 25-50 cm long) nests with Astrapotherium in a marsupial clade near Monodelphis domestica. The incisor canines were reduced here. That happens because fossils are so rare. The skeleton above is Meniscotherium.

Ocepeia daouiensis (Gheerbrant et al 2001, 2014; Paleocene, 60 mya; 9 cm skull length) is from Morocco. Here it nests with Orthaspidotherium and Meniscotherium. The pneumatized skull contains many air spaces. Slightly larger skulls have larger canines and so are considered male, but may just be older. This specimen has only a tiny canine on a broken maxilla. The molar teeth are relatively large and the jugal deepens below the orbit, hiding the posterior molars in lateral view. Note the dorsal eyes, as in hippos. Ocepeia was found with aquatic taxa and was probably amphibious. The name Ocepeia derives from the initials of Office Chérifien des Phosphates (O.C.P.), the national Moroccan phosphate mining company.

Orthaspidotherium edwardsi (Ladeveze et al. 2010; Late Paleocene, 58 mya, 7.5cm skull length) nests with Meniscotherium. The skull is twice as wide as tall on this weasel-like terrestrial mammal. The jawline is convex at the canine and beneath the orbit. The lacrimal/jugal/zygomatic arch is quite robust.

Argot C 2010. Morphofunctional analysis of the postcranium of Amphicyon major (Mammalia, Carnivora, Amphicyonidae) from the Miocene of Sansan (Gers, France) compared to three extant carnivores: Ursus arctos, Panthera leo, and Canis lupus. Geodiversitas 32 (1): 65-106.

Bergounious FM and Crouzel FC 1973. Amphicyon major Blainville du Miocene moyen de Sansan (Gers). Ann. Paleont., t. 59, fas. 1, pp. 3-76,47 fig. Paris.

Blainville H 1841. Osteographie et description iconographique comparée du squelette et du systéme dentaire des cinq classes d’animaux vertébrés récents et fossiles. Vol. 6, Carnassiers. Paris: Arthus Bertrand.

Cope ED 1872. Descriptions of some new Vertebrata from the Bridger Group of the Eocene. Proceedings of the American Philosophical Society 12:460-465.

Cope ED 1874. Report of the Chief of Engineers for. 1874 Vol. II, Pt. II, Appendix FFa of Appendix FF, pp. 115-130.

Ladevèze S, Missiaen P and Smith T 2010. First Skull Of Orthaspidotherium Edwardsi (Mammalia, "Condylarthra") From The Late Paleocene Of Berru (France) And Phylogenetic Affinities Of The Enigmatic European Family Pleuraspidotheriidae. Journal of Vertebrate Paleontology 30(5): 1559–1578.

Lartet E 1836. Nomenclature des mammiféres et des coquilles qu’il a trouvés dans un terrain d’eau douce prés de Simorre et de Sansan (Gers). Bulletin de la Société Géologique de France 7: 217–220.

Leidy J 1870. Remarks on a collection of fossils from the western territories. Proceedings of the Academy of Natural Sciences of Philadelphia 22: 109–110.

Osborn HF and Granger W 1932. Coryphodonts and uintatheres from the Mongolian expedition of 1930. American Museum Novitates 552:1-16.

Williamson TE and Lucas SG 1992. Meniscotherium (Mammalia, "Condylarthra") from the Palaeocene-Eocene of Westeran North America. New Mexico Museum of Natural Hstory and Science Bulletin 1.

wiki/Meniscotherium
wiki/Hyopsodus
wiki/Amphicyon
wiki/Ocepeia
wki/Orthaspidotherium