Abstract
AbstractIn this contribution, we investigate two sparassodonts from the Sarmiento Formation (Colhuehuapian Age; Early Miocene) recovered at the Patagonian locality of Sacanana, Chubut Province, Argentina. The first specimen (MACN-Pv CH1911), identified as Sipalocyon externus, is an almost complete cranium with upper dentition. The second specimen (MACN-Pv CH40), referred to Borhyaena macrodonta, consists of a fragmentary rostral portion of the face with associated m3–m4. The cranium of S. externus was studied through µCT-scanning to investigate its internal anatomy and infer paleoecological aspects of olfaction and hearing. In general, the endocranial anatomy and encephalization quotient are like those of other metatherians. We report the presence of an accessory transverse diploic sinus that has not previously been described in marsupials. Elements of the nasal cavity (e.g., turbinals, ossified nasal septum, cribriform plate) of S. externus exhibit features that are widespread among marsupials. Sense of olfaction, as evaluated from the cribriform plate and the 3D models of the olfactory bulbs, appears to have grossly resembled that of the domestic cat, a well-researched therian proxy. The dimensions of the tympanic membrane, as estimated from the preserved ectotympanic, suggest that the optimal hearing frequency of S. externus would have been similar to that of extant carnivorous marsupials. In sum, our study suggests that S. externus was a typical small-bodied (2–3 kg) hypercarnivorous metatherian that primarily relied on vision to hunt its prey, complemented by other sensory capabilities (olfaction and hearing), in a similar manner to small felids.
Funder
Agencia Nacional de Promoción Científica y Tecnológica
Publisher
Springer Science and Business Media LLC
Reference145 articles.
1. Abello, M. A. (2007). Sistemática y bioestratigrafía de los Paucituberculata (Mammalia, Marsupialia) del Cenozoico de América del Sur. [Doctoral dissertation, Universidad Nacional de La Plata]. Available at: http://naturalis.fcnym.unlp.edu.ar/id/20120126000025. Accessed 15 October 2021.
2. Abràmoff, M. D., Magalhães, P. J., & Ram, S. J. (2004). Image processing with ImageJ. Biophotonics International, 11(7), 36–42.
3. Aitkin, L. M. (1998). Hearing—the Brain and Auditory Communication in Marsupials. Springer-Verlag.
4. Aitkin, L. M., Nelson, J. E., & Shepherd, R. K. (1994). Hearing, vocalization and the external ear of a marsupial, the Northern quoll, Dasyurus hallucatus. The Journal of Comparative Neurology, 349(3), 377–388. https://doi.org/10.1002/cne.903490305
5. Allen, H. (1882). On a revision of the ethmoid bone in the Mammalia, with special reference to the description of this bone and the sense of smelling in the Cheiroptera. Bulletin of the Museum of Comparative Zoology, 10(3), 135–171.