Ontogenetic and Adult Shape Variation in the Endocast of Tapirus: Implications for T. polkensis from the Gray Fossil Site

• Main Author: Gaetano, Thomas M
• Format: Others
• Language: English
• Published: Digital Commons @ East Tennessee State University 2020
• Subjects: Paleoneurology; Tapir; Endocast; Gray Fossil Site; Sociality; Sensory Ecology; Other Neuroscience and Neurobiology; Paleobiology; Paleontology; Zoology
• Online Access: https://dc.etsu.edu/etd/3765; https://dc.etsu.edu/cgi/viewcontent.cgi?article=5254&context=etd

Endocranial morphology provides evidence of sensory ecology and sociality of extinct vertebrates. The Earliest Pliocene Gray Fossil Site (GFS) of NE Tennessee features a conspicuous dominance of skeletal elements belonging to the dwarf tapir, Tapirus polkensis. Numerous individuals in one fossil locality often suggests gregarious behavior, but sociality in T. polkensis contradicts behavior documented for extant Tapirus species. I test T. polkensis for variation in sensory and social ecology using computed tomography and 3D digital endocasts from an ontogenetic sequence. I compare the T. polkensis endocasts with extant Tapirus species using Encephalization Quotients (EQs) and 3D geometric morphometrics. Results show conserved endocast morphology for Tapirus, and thus, conserved sensory and social ecology. Tapirus behavior is likely consistent for ~5 Ma, and extant Tapirus behavior can be inferred for T. polkensis. The large number of individuals from the GFS is likely the result of a preservation bias unrelated to gregariousness.