Alcidedorbignya, Ectoconus and Pantolambda

Vertebrata

Fish

Tetrapoda

Reptilia/Amniota

Archosauromorpha

Basal Archosauromorpha

Mammalia

Terrestrial Younginiformes

Marine Younginiformes

Lepidosauromorpha

Cephalerpeton clade

Captorhinidae

Milleretta Limnoscelis clade

Bolosaurus Diadectes clade

Turtle Pareiasaur clade

Fenestrasauria • Pterosauria

Protosquamata

Squamata

Alcidedorbignya inopinata (Muizon and Marshall 1992 Muizon et al 2015; MHNC 8372, Early Paleocene, 64 mya; scale bar is 2cm) was originally considered a basal pantodont (Condylartha) close to Pantolambda and the origin of ungulates and digging placentals. The rostrum is curved with a smaller naris. Long hooves are former claws on a semiplantigrade manus.

Ectoconus ditrigonus (Cope 1884 Early Paleocene, 66-63mya, sheep-sized) is tradiitionally considered a basal condylarth known from a rare complete skeleton. Here Ectoconus is derived from the marsupials, Alcidedorbignya and Monodelphis. It is a sister to Pantolambda. Though canines were present, Ectoconus was an herbivore with five digits on all four limbs. Shown here digitigrade, this taxon was likely plantigrade. Another species, Ectoconus majusculus, is shown here.

Pantolambda bathmodon (Cope 1882, Middle Paleocene, 66-63 mya, sheep-sized; AMNH 3956) is traditionally another basal condylarth and a pantodont. Here Pantolambda is a marsupial derived from Monodelphis and the taxa on this page, including Ectoconus. Pantolambda had a shorter skull, shorter lumbar region and shorter limbs. The cervical series appears gracile here, but that may be due to fossil erosion.

Cope ED 1882. On the condylarthra. Academy of Natural Sciences of Philadelphia Proceedings 1882:95-97.

Cope ED 1882. Synopsis of the Vertebrata of the Puerco Eocene epoch. Proceedings of the American Philosophical Society 20

Cope ED 1884. The Amblypoda. The American Naturalist 18 (112):6=461-471.

Simons EL 1960. The Paleocene Pantodonta. Transactions of the American Philosophical Society, New Series 50(6):1-8.

de Muizon C de & Marshall LG 1992. Alcidedorbignya inopinata (Mammalia: Pantodonta) from the early Paleocene of Bolivia: phylogenetic and paleobiogeographic implications. Journal of Paleontology 66 (3): 499-520.

deMuizon C, Billet G, Argot C, Ladeveze S and Goussard F 2015. Alcidedorbignya inopinata, a basal pantodont (Placentalia, Mammalia) from the early Palaeocene
of Bolivia: anatomy, phylogeny and palaeobiology. Geodiversitas 87(4):397-634.

wiki/Alcidedorbignya
wiki/Ectoconus
wiki/Pantolambda