Hypercarnivorous Tendency As A Probable Cause of The Cat Gap
The history of carnivorous mammals is characterized by a series of rise-and-fall patterns of diversification in which declining clades are replaced by phylogenetically distinct but functionally similar clades. Over the past 50 million years, successive clades of small and large carnivorous mammals diversified and then declined to extinction. In most instances, the cause of the decline was energetic constraints and pervasive selection for larger size (Cope's rule) that lead to (hypercarnivory) dietary specialization. Hypercarnivory leads to increased vulnerability of extinction.
The nimravids were large cats that occupied this ecomorphic niche in the ecosystem until 26 Ma. It is highly likely that their hypercarnivory led to their extinction in North America. After the extinction of the nimravids there were no other feliform or Felidae species until other felids arrived from Eurasia after crossing the Bering land bridge 18.5 million years ago. During this time there was great diversity among the other carnivorous mammals in North America – both hypocarnivory and hypercarnivory species – and other hypercarnivory species existed before, during, and after the cat gap.
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