From Newsgroup: sci.bio.paleontology

Evolutionary patterns of cat-like carnivorans unveil drivers of the
sabertooth morphology

Highlights

There is a continuous spectrum of cat-like phenotypes with sporadic convergence

Saber-toothed taxa show reduced integration and high early evolutionary
rates

Disparity is high among sabertooths, yet cat-like carnivorans decline
after the Miocene

The emergence of large sabertooths appears to act as a macroevolutionary ratchet

Summary

The sabertooth morphology stands as a classic case of convergence,
manifesting recurrently across various vertebrate groups, prominently
within two carnivorans clades: felids and nimravids. Nonetheless, the evolutionary mechanisms driving these recurring phenotypes remain insufficiently understood, lacking a robust phylogenetic and
spatiotemporal framework. We reconstruct the tempo and mode of craniomandibular evolution of Felidae and Nimravidae and evaluate the
strength of the dichotomy between conical and saber-toothed species, as
well as within saber-toothed morphotypes. To do so, we investigate morphological variation, convergence, phenotypic integration, and
evolutionary rates, employing a comprehensive dataset of nearly 200 3D
models encompassing mandibles and crania from both extinct and extant feline-like carnivorans, spanning their entire evolutionary timeline.
Our results reject the hypothesis of a distinctive sabertooth
morphology, revealing instead a continuous spectrum of feline-like
phenotypes in both the cranium and mandible, with sporadic instances of unequivocal convergence. Disparity peaked at the end of the Miocene and
is usually higher in clades containing taxa with extreme sabertoothed adaptations. We show that taxa with saberteeth exhibit a lower degree of craniomandibular integration, allowing to exhibit a greater range of phenotypes. Those same groups usually show a burst of morphological evolutionary rate at the beginning of their evolutionary history. Consequently, we propose that a reduced degree of integration coupled
with rapid evolutionary rates emerge as key components in the
development of a sabertooth morphology in multiple clades.

Open access: https://www.cell.com/current-biology/fulltext/S0960-9822(24)00529-3
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