Quantitative analyses of feliform humeri reveal the existence of a very large cat in North America during the Miocene: Supplementary data

Felids are keystone predators in modern ecosystems and likely played a
similar role in shaping ecosystem through the Cenozoic. Unfortunately,
understanding the paleoecological impact of felids has been hampered by
taxonomic confusion and uncertainty in big cat diversity through time.
This stems, in part, from the importance of dentition in differentiating
feliform taxa combined with the abundance of postcrania in the fossil
record. This dilemma is best illustrated by the humeri of a very large
felid uncovered from a number of Hemphillian-aged localities in North
America that, in the absence of craniodental remains, have not previously
been definitively identified. We present the results of an analysis of the
potential of isolated distal humeri to identify feliform taxa. We compared
the form and size of distal humeri across feliforms using geometric
morphometric analysis and used linear measurements to reconstruct body
mass and estimate prey size. Our results suggest that distal humeri are
useful tools for differentiating feliform families, genera, and species.
Further, along with a specimen from Idaho with associated dentition, they
suggest that the large Hemphillian-aged felid is a new species of
Machairodus. Future phylogenetic analyses will be necessary to reconstruct
the evolutionary history of North American Machairodontinae, but this new
taxon provides evidence for a diverse predator fauna during the late
Miocene of North America that included some of the largest felids in Earth
history.