Sabercat is practically synonymous with Smilodon. Fossils of the famous knife tooth have been found by the hundreds in the La Brea asphalt seeps of Los Angeles, and the South American species – Smilodon populator – was one of the largest sabertooths of all time, the largest of which were bulkier than a tiger. But as far as skulls go, at least, Smilodon can’t lay claim to the Biggest Sabercat superlative. That honor goes to a different carnivore.
Paleontologists Deng Tao, Zhijie Tseng, and colleagues set the record straight in a new paper all about a huge skull of Machairodus horribilis. The fossil, found in the roughly 8.3 million year old rock of China’s Longjiagou Basin, is a little bit crushed. Time and the caprices of geology have squished the cheeks and wide frontal bones of the skull into a much narrower profile. Reconstructed to its shape in life, however, the cream-colored cranium represents a menacingly large sabercat.
The new Machairodus horribilis skull measures over 16 inches long. That’s not only longer than all other known skulls of contemporary sabercats, but also those of the Ice Age celebrities Smilodon and Homotherium. That translates to an estimated body mass of over 892 pounds for this particular Machairodus horribilis, putting it in the same range as the burly Smilodon populator. However you care to slice it, this was one big cat.
It would be a mistake to treat Machairodus horribilis just like any other sabercat, though. While the feline shared the long, serrated fangs and other modifications seen in its relatives, for example, Deng and colleagues point out that Machairodus horribilis had a relatively small gape. The cat could only open its mouth about 70 degrees, comparable to what modern lions are capable of, rather than the ludicrous 120 degrees Smilodon could achieve. Along with differences in muscle attachments, the paleontologists write, this means that Machairodus horribilis may have targeted relatively smaller prey than later sabercats tackled.
Machairodus horribilis comes to us, then, as something that was neither like modern cats nor like later sabercats. Its thin canines would have dictated a targeted throat bite, yet the limitations of its muscles and gape likely limited the size of its preferred prey to a narrower range. To cut it short, big predators did not always pounce upon even larger prey.
Deng, T., Zhang, Y., Tseng, Z., Hou, S. 2016. A skull of Machairodus horribilis and new evidence for gigantism as a mode of mosaic evolution in machairodonts (Felidae, Carnivora). Vertebrata PalAsiatica. 54 (4): 302-318