Comparative morphology and postnatal ontogeny of the bony labyrinth in Pantherinae (Felidae, Carnivora) with special emphasis on the lion

Abstract

The bony labyrinth (inner ear) of mammals reveals systematic as well as morphofunctional information. However, detailed knowledge of bony labyrinth morphology and ontogeny in Pantherinae, that comprise some of the most iconic mammals, is still pending. Hence, we present the first comparative description of the bony labyrinth in all extant species of Panthera and Neofelis some of which are represented by several postnatal stages; particular focus is set on Panthera leo. Our study is based on µCT scans and virtual 3D reconstructions and accompanied by selected morphometric measurements. Even though quite similar in morphology, both genera as well as their species can be distinguished by several features, e.g., shape and relative size of the semicircular canals and presence or absence of an osseous secondary crus commune. In case of the latter, P. pardus shows some intraspecific variation. We also traced the reduction of the fossa subarcuata during ontogeny in P. leo which conforms with previous studies. Negative allometry of the bony labyrinth in relation to skull basal length can be observed during ontogeny as demonstrated by P. leo as well as between different sized species. Although not correlated with the length of the cochlear canal, the number of cochlear turns is higher in captive non-adult P. leo and P. tigris, but lower in adult captive P. pardus. If these intraspecific differences are related to captivity or represent an ontogenetic pattern, needs to be evaluated in future studies based on larger samples.