New Middle Eocene proboscidean from Togo illuminates the early evolution of the elephantiform-like dental pattern

Abstract

Africa has played a pivotal role in the evolution of early proboscideans (elephants and their extinct relatives), yet vast temporal and geographical zones remain uncharted on the continent. A long hiatus encompassing most of the Eocene (Ypresian to the Early Priabonian, around 13 Myr timespan) considerably hampers our understanding of the early evolutionary history of the group. It is notably the case with the origin of its most successful members, the Elephantiformes, i.e. all elephant-like proboscideans most closely related to modern elephants. Here, we describe a proboscidean lower molar discovered in Lutetian phosphate deposits from Togo, and name a new genus and species, Dagbatitherium tassyi . We show that Dagbatitherium displays several elephantiform dental characteristics such as a three-layered Schmelzmuster, the presence of a mesoconid, transversely enlarged buccal cusps and the individualization of a third lophid closely appressed to a minute distal cingulid. Dagbatitherium represents a stem Elephantiformes, pushing back the origin of the group by about 10 Myr, i.e. a third of its currently known evolutionary history. More importantly, Dagbatitherium potentially unlocks the puzzle of the origin of the unique elephantiform tooth crown organization by bridging a critical temporal and morphological gap between early bunodont incipiently bilophodont proboscidean taxa and more derived elephantiforms.

3D models related to the publication: New middle Eocene proboscidean from Togo illuminates the early evolution of the elephantiform-like dental pattern.

“…We present here the 3D model of a proboscidean specimen discovered in middle Eocene phosphate deposits from Dagbati (Togo) and belonging to a new genus and species, Dagbatitherium tassyi (Hautier et al, 2021; see Table 1 and Fig. 1).…”

“…Dagbatitherium displays several elephantiform dental characteristics such as a three-layered Schmelzmuster, the presence of a mesoconid, transversely enlarged buccal cusps, and the individualization of a third lophid associated to a minute distal cingulid. This new proboscidean taxon potentially represents the oldest record of the Elephantiformes and bridges a critical temporal and morphological gap in the proboscidean fossil record (Hautier et al, 2021). A 3D model of the enamel cap and dentine was reconstructed in order to reveal hidden anatomical features and characterize differences in enamel thickness.…”