The Cave Lion (Panthera spelaea and Panthera fossilis)

[GuateGojira]

Thank you fro the information @Kingtheropod.

I know that this is not a topic of Smilodon, but just to continue in the line of the conversation, these are the two studies about the sexual domorphism in Smilodon fatalis, and the results are contradictory at some degree.

1. J. A. Meachen-Samuels and W. J. Binder: Sexual dimorphism and ontogenetic growth in the American lion and sabertoothed cat from Rancho La Brea - 2010.
Abstract: Sexual dimorphism has long been purported in the American lion Panthera atrox well‐known from the asphalt deposits at Rancho La Brea. However, few studies have quantified this dimorphism. Along with the sabertoothed cat, Smilodon fatalis, we examine sexual dimorphism in dentaries from the Rancho La Brea tar pits using extant Panthera leo as a guide. Although growth rate in large carnivores declines after a certain age, it has been demonstrated to continue well beyond adulthood, therefore age must also be incorporated into a measure of sexual dimorphism in large carnivores. Prior studies demonstrated that tooth wear can be an inaccurate measure of age in Rancho La Brean carnivores, as it is affected by both diet and age. This study, instead, uses per cent pulp cavity closure of the lower canine tooth which is solely a measure of relative age, combined with linear measurements of the dentaries to separate the sexes of these two extinct cats. Results show that P. atrox has similar, or slightly greater, levels of sexual dimorphism than P. leo, whereas S. fatalis shows little to no sexual dimorphism. Our results also demonstrate that both Panthera species continue to grow into adulthood, strengthening the case that it is necessary to incorporate a measure of age into studies of sexual dimorphism in large carnivores, living or extinct.
Link: https://zslpublications.onlinelibrary.wi...09.00659.x

2. Per Christianse and John M. Harris: Variation in Craniomandibular Morphology and Sexual Dimorphism in Pantherines and the Sabercat Smilodon fatalis - 2012.
Abstract: Sexual dimorphism is widespread among carnivorans, and has been an important evolutionary factor in social ecology. However, its presence in sabertoothed felids remains contentious. Here we present a comprehensive analysis of extant Panthera and the sabertoothed felid Smilodon fatalis. S. fatalis has been reported to show little or no sexual dimorphism but to have been intraspecifically variable in skull morphology. We found that large and small specimens of S. fatalis could be assigned to male and female sexes with similar degrees of confidence as Panthera based on craniomandibular shape. P. uncia is much less craniomandibularly variable and has low levels of sexual size-dimorphism. Shape variation in S. fatalis probably reflects sexual differences. Craniomandibular size-dimorphism is lower in S. fatalis than in Panthera except P. uncia. Sexual dimorphism in felids is related to more than overall size, and S. fatalis and the four large Panthera species show marked and similar craniomandibular and dental morphometric sexual dimorphism, whereas morphometric dimorphism in P. uncia is less. Many morphometric-sexually dimorphic characters in Panthera and Smilodon are related to bite strength and presumably to killing ecology. This suggests that morphometric sexual dimorphism is an evolutionary adaptation to intraspecific resource partitioning, since large males with thicker upper canines and stronger bite forces would be able to hunt larger prey than females, which is corroborated by feeding ecology in P. leo. Sexual dimorphism indicates that S. fatalis could have been social, but it is unlikely that it lived in fusion-fission units dominated by one or a few males, as in sub-Saharan populations of P. leo. Instead, S. fatalis could have been solitary and polygynous, as most extant felids, or it may have lived in unisexual groups, as is common in P. leo persica.
Link: https://journals.plos.org/plosone/articl...ne.0048352 

The study of Christiansen & Harris (2012) seems to be more olistic, more complete, so I am with them in this case, which means that there was sexual dimorphism in the Smilodon fatalis population, although it was not as large as other Panthera members. Is interesting to see that there is practically no sexual dimorphism in the snow leopards based in skulls, and although the males do weight more, in body dimentions there is practically no diference (these last two things from my own unpublished investigation). Reply