RESTUDY OF PERMO-CARBONIFEROUS SYNAPSID EDAPHOSAURUS-NOVOMEXICANUS WILLISTON AND CASE, THE OLDEST KNOWN HERBIVOROUS AMNIOTE

Reexamination of the holotype and the description of new material of E daphosaurus novomexicanus from the Permo-Pennsylvanian Cutler Formatio n of north-central New Mexico reveals that this species is the most pr imitive member of the Edaphosaurus clade. This assignment, based previ ously upon supposed plesiomorphies of the postcrania, is supported her e by two primitive character states that occur in a derived form in th e Texan species of Edaphosaurus. The presence of two autapomorphies in E. novomexicanus suggests that this species is probably not a morphol ogical relict, as previously supposed, but may be part of a lineage th at did not exhibit the level of diversification seen in its probable s ister group, the clade of Texan edaphosaurids (E. boanerges, E. crucig er, and E. pogonias).