Myriam Boivin (LPG) : «New insights into the evolutionay history of caviomorph rodents from the Paleogene and Neogene of Peruvian Amazonia»

Jeudi 20 Décembre 2018, 11:00 - 12:00
par Mickaël BONNIN

Caviomorph rodents represent one of the most successful groups of placental mammals from South America. They are represented nowadays by four superfamilies: Cavioidea (guinea pigs and their allies), Chinchilloidea (chinchillas and their allies), Octodontoidea (spiny rats and their allies) and Erethizontoidea (New World porcupines). Despite their high modern and Neogene diversity, their evolutionary history has long remained obscure notably during the Paleogene and in the low-latitudes of South America. The Amazonia, located in the Neotropic low latitudes, is one of the geographical areas that today focus the maximum of the specific richness of caviomorphs. However, the fossil record of this region has long remained embryonic form. Indeed, because of the dominant vegetation cover, aggressive pedogenesis, seasonal flooding and frequent landslides, outcrops likely to yield fossils are very rare, and most of the time difficult to access. Recent paleontological investigations in Peruvian Amazonia (Contamana and Tarapoto areas) allowed for the discovery of 18 Paleogene and one Miocene localities yielding many new fossils of caviomorphs (mainly isolated teeth). Their study reveals a rich alpha-taxonomic diversity of caviomorphs in Peruvian Amazonia during the late Middle Eocene, Early Oligocene, Late Oligocene and Middle Miocene. Besides, a mandibular fragment of a giant caviomorph from another Peruvian Amazonian locality (Monte Salvado area, probably Late Miocene in age) was also studied. It constitutes the second record of Phoberomys in Peru. A cladistic assessment with a comprehensive taxonomic sampling including most families of the four superfamilies was undertaken. This analysis allows a better understanding of the evolutionary history of caviomorphs in terms of morphological evolution, emergence and diversification of main groups, and biogeographical history.

Lieu : Amphithéâtre du bâtiment 4