Peratherium

Abstract: Metatherian (marsupial) and eutherian (placental) mammals are end members of a complex, possibly common North American1–4 or, less likely, a South American5 stock that diverged before the early late Cretaceous and underwent separate adaptive radiations establishing them as the two dominant mammalian groups (subclass Theria). By the later Cretaceous, marsupials were well situated in North America3 and were also present in South America6. Their oldest occurrences in Antarctica (later Eocene7) and Australia (Oligocene8) are artefacts of exceptionally poor fossil records of mammals on those continents and it is clear that the Metatheria must have been quite diverse in both areas (physically connected in pre-Eocene times9) very much earlier5,7. Marsupials probably did not reach Europe much before their earliest record there in the early Eocene10. The Metatheria have not been identified from Asia, nor until now from Africa. We now report the discovery of the first fossil remains of a didelphid marsupial in Oligocene rocks in North Africa.

Abstract: New specimens of Peratherium africanum from Early Oligocene deposits of the Fayum, Egypt, provide key information on the relationships of the species. These include the first maxilla to be found and two additional dentaries. The maxilla can be demonstrated to belong to the same species as the holotype dentary by study of the occlusal relationships of upper and lower molars. It can be shown by several synapomorphies that P. africanum is the sister species to European Bartonian–Rupelian Peratherium lavergnense. P. africanum therefore belongs to the 'didelphimorph' family Herpetotheriidae, not to the peradectimorph family Peradectidae. The genus Qatranitherium, previously erected for this species alone, is here synonymized with Peratherium. Comparison with 'didelphimorphian' taxa from early Paleogene deposits of South America suggests more remote relationships, indicating an origin for P. africanum by dispersal from Europe as originally envisaged. The more precise relationships deduced here help to constrain the time interval for dispersal to Afro-Arabia, probably during the earliest Oligocene sea-level low

Abstract: The known range of Peratherium is extended to the Lower Harrison Miocene by the discovery of Peratherium youngi, new species Nanodelphys minutus, new genus and species, is described and placed in the Thlaeodontinae, a subfamily previously known only from the Cretaceous This newly discovered specimen is from the Brule, Oligocene, and thus greatly extends the known geologic range of the group

Abstract: The earliest Eocene locality of Dormaal (Belgium) has provided the oldest Cenozoic herpetotheriid marsupials of Europe. No herpetotheriid has ever been reported earlier than the Eocene in Europe, except for a questionable single upper molar from the Upper Cretaceous of the Belgian/Dutch border. The systematics of the herpetotheriids of Dormaal was formerly based on only a dozen dental specimens, which were assigned, after several revisions, to two species Peratherium constans and Amphiperatherium brabantense. Most importantly, these two species were considered at the root of most of the hepetotheriid lineages of the European Paleogene. Here we report a large sample of about 400 new dental remains that allow a better definition of both species as well as a testing of their systematic status. The evidence of significant morphological variability leads us to reconsider the diagnosis of Peratherium constans and to question the validity of Amphiperatherium brabantense. This study highlights that the primitive species Peratherium constans and Amphiperatherium brabantense are hardly distinguishable from each other, and therefore conclude that Peratherium constans was the only marsupial present at Dormaal. The important morphological variation exhibited by this herpetotheriid is similar to the variability observed in the type-species Peratherium elegans and in other fossil and extant metatherians. Consequently, our results suggest that several Amphiperatherium species from the Eocene could represent variants of the genus Peratherium. The question of the Amphiperatherium presence in Europe is therefore raised and a thorough discriminate analysis of both genera should be conducted in later works.