NEW FOSSILS OF PALAEOAMASIA KANSUI (MAMMALIA, EMBRITHOPODA): IMPLICATIONS FOR EMBRITHOPOD EVOLUTION

Embrithopods are an enigmatic order of Afrotheria (Mammalia) represented since the early 1900s only by late Paleogene African arsinoitheres. In 1979, however, Sen and Heintz attributed the western Asian mid Paleogene genus Palaeoamasia to Embrithopoda. This genus was known only by a handful of dental specimens and the dental formula and complete morphology is unknown. This project focuses on new Lutetian (43 Ma) dental material from the Uzunçarşıdere Formation of Central Turkey, including a nearly complete maxilla of Palaeoamasia kansui. Through comparison with other specimens of Palaeoamasia kansui and geologically older and younger embrithopod species from Africa, as well as penecontemporaneous species from Turkey and eastern Europe, it can be determined that Palaeoamasia kansui contains an unexpected mix of ancestral and derived features, in that cheek tooth crown morphology resembles the ancestral condition, but the presence of a marked diastema between the anterior and posterior dentition is derived with respect to the earliest known embrithopods. This project sheds light on embrithopod relationships, demonstrating that there are two distinct evolutionary trajectories in the order Embrithopoda: one in Africa that produced massive body size and specialized cheek tooth crown morphology while retaining a primitive anterior dental battery, and a separate one in Eurasia that produced a unique dental formula and apparently more derived anterior dental morphology while conserving small body size and primitive cheek tooth crown morphology. This project was supported by NSF grants EAR-1543684 and EAR-1923294.