Synchrotron radiation reveals the identity of the large felid from Monte Argentario (Early Pleistocene, Italy)

Marco Cherin,Marco Zanatta,Roberto Rettori,Raffaele Sardella,Dawid A Iurino,Alessandro Paciaroni,Vincent Fernandez,Caterina Petrillo

doi:10.1038/s41598-018-26698-6

Marco Cherin, Marco Zanatta + Show 6 more

Open Access

https://doi.org/10.1038/s41598-018-26698-6

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Abstract

We describe here a partial skull with associated mandible of a large felid from Monte Argentario, Italy (Early Pleistocene; ~1.5 million years). Propagation x-ray phase-contrast synchrotron microtomography of the specimen, still partially embedded in the rock matrix, allows ascribing it reliably to Acinonyx pardinensis, one of the most intriguing extinct carnivorans of the Old World Plio-Pleistocene. The analysis of images and 3D models obtained through synchrotron microtomography – here applied for the first time on a Plio-Pleistocene carnivoran – reveals a mosaic of cheetah-like and Panthera-like features, with the latter justifying previous attributions of the fossil to the extinct Eurasian jaguar Panthera gombaszoegensis. Similarly, we reassign to A. pardinensis some other Italian materials previously referred to P. gombaszoegensis (sites of Pietrafitta and Ellera di Corciano). The recognition of Panthera-like characters in A. pardinensis leads to reconsidering the ecological role of this species, whose hunting strategy was likely to be different from those of the living cheetah. Furthermore, we hypothesise that the high intraspecific variation in body size in A. pardinensis can be the result of sexual dimorphism, as observed today in all large-sized felids.

Highlights

The Villafranchian Land Mammal Age (LMA) is a biochronological unit based on large mammals roughly spanning from the late Pliocene to most of the Early Pleistocene[1]
We report on the results of the microtomographic analysis of the felid skull from Monte Argentario based on SR technology and discuss about the morphological variation and ecology of A. pardinensis
Figure 4. 3D models of the Acinonyx pardinensis skull from Monte Argentario. (a,b) Damaged and fragmented skull in rostral (a) and right lateral (b) views: (c–d) Reconstructed skull with cloned and mirrored portions highlighted in different colour, in rostral (c) and right lateral (d) views

Summary

Introduction

The Villafranchian Land Mammal Age (LMA) is a biochronological unit based on large mammals roughly spanning from the late Pliocene to most of the Early Pleistocene (about 3.5–1.0 million years; Ma)[1]. The craniodental morphology and the development of jaw muscles associated with the large body size, suggest that A. pardinensis could kill large prey with a hunting strategy akin to those of pantherine felids, rather than that of the cheetah[6] This hypothesis is supported by recent analysis[16] of the inner ear anatomy of extant and extinct felids, according to which the vestibular system of modern cheetahs is unique in showing adaptations to facilitate visual and postural stability during high-speed prey pursuits and is extremely different in shape and proportions relative to other species, including A. pardinensis. The felid partial skull with associated mandible discovered in the Late Villafranchian site of Monte Argentario (Tuscany, Italy) (Fig. 2) represents a key specimen for understanding this species’ functional morphology It shows a mosaic of intermediate characters between Acinonyx (e.g., the shortened snout) and Panthera (e.g., the massive canines). It was necessary to resort to the most advanced technologies available in the field of tomographic investigations

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