Neurosensory anatomy and function in Dimetrodon, the first terrestrial apex predator

Kayla D Bazzana-Adams; David C Evans; Robert R Reisz

doi:10.1016/j.isci.2023.106473

Neurosensory anatomy and function in Dimetrodon, the first terrestrial apex predator

iScience. 2023 Mar 21;26(4):106473. doi: 10.1016/j.isci.2023.106473. eCollection 2023 Apr 21.

Authors

Kayla D Bazzana-Adams^{1

2

3}, David C Evans^{2

3}, Robert R Reisz^{1

4}

Affiliations

¹ Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada.
² Department of Natural History, Royal Ontario Museum, Toronto, ON, Canada.
³ Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada.
⁴ International Center of Future Science, Dinosaur Evolution Research Center, Jilin University, Changchun, Jilin Province, China.

Abstract

Dimetrodon is among the most recognizable fossil taxa, as well as the earliest terrestrial amniote apex predator. The neuroanatomy and auditory abilities of Dimetrodon has long been the subject of interest, but palaeoneurological analyses have been limited by the lack of three-dimensional endocast data. The first virtual endocasts reveal a strongly flexed brain with enlarged floccular fossae and a surprisingly well-ossified bony labyrinth clearly preserving the semicircular canals, along with an undifferentiated vestibule and putative perilymphatic duct. This first detailed palaeoneurological reconstruction reveals potential adaptations for a predatory lifestyle and suggests Dimetrodon was able to hear a wider range of frequencies than anticipated, potentially being sensitive to frequencies equal to or higher than many extant sauropsids, despite lacking an impedance matching ear. Ancestral state reconstructions support the long-standing view of Dimetrodon as representative of the ancestral state for therapsids, while underscoring the importance of validating reconstructive analyses with fossil data.

Keywords: Biological sciences; Palaeohistology; Paleobiology.