Brave New Worlds: The Holarctic reign of Machairodus
During the Miocene, North America was home to an impressive array of sabertoothed predators. Some of them belonged to the Barbourofelidae, a family of carnivores that developed extreme sabertooth adaptations and became extinct during the late Miocene; others were true sabertoothed cats, members of the family Felidae.
Among the latter, there were several species that look superficially very similar to one another, and paleontologists have a hard time trying to sort out their relationships. Were all these species part of a single, native American lineage spanning much of the Miocene period? or perhaps some of them arrived to North America from the Old World as part of succesive immigration events?
This may sound like a very technical issue, but it touches the very core subject of sabertooth evolution: we know that the sabertooth morphology is an adaptation for a very specific killing technique, but, how much of that morphology is the result of shared ancestry and how much is the result of convergence?
After this somewhat technical introduction, let me introduce to you an amazing sabertooth cat: Machairodus catocopis. This predator had the approximate size and body proportions of a modern tiger, but it was armed with elongated, laterally flattened upper canine teeth with coarsely serrated margins that allowed it to kill large prey almost instantly through massive blood loss. It also had a huge “dewclaw” that it used for literally hooking its prey.
Years after its original description, this species was removed from the genus Machairodus and assigned to Nimravides, a change that reflected the belief that it was part of a native lineage of cats that had evolved in North America for many milions of years. Those changes in classification had been made on the basis of fragmentary fossils, but several years ago at the American Museum of Natural History (New York) collections I came across a couple of undescribed specimens that were amazingly well preserved, and they seemed to me strikingly similar to the fossils of Machairodus aphanistus that we were finding in the fossil sites of Cerro Batallones, in Spain.
Now in collaboration with my colleagues Manuel Salesa and Gema Siliceo from the Museo Nacional de Ciencias Naturales (CSIC) I have finally been able to look in detail at the anatomy of those wonderful American fossils, and we have found that the similarities with the Spanish specimens go very deep indeed. This study, now published in the Journal of Vertebrate Paleontology, clearly indicates that Edward Drinker Cope (back in 1887!) was right from the start to classify this animal in the genus Machairodus: it is so closely related to the Batallones sabertooth that if we found its fossils in a Spanish site we would consider it just a slightly more advanced form of the same group. The geological ages of the two populations are consistent with the possibility that the ancestors of M. catocopis arrived to North America as part of a migration wave from the Old World. The original migrant must have been almost identical to the Batallones cat: an immensely powerful animal that had the potential to invade continents and rule as top predator thanks to the combination of a versatile feline body plan and a pair of precociously specialized scimitar-like canines.
By the way, don’t bother to look for Machairodus catocopis in my upcoming book “Sabertooth”. The book went into press before our new paper was published, so I had to stick to the previous classification and call it “Nimravides catocopis”…
Here is the title of our new pubication:
Antón, M, M. J. Salesa and G. Siliceo 2013. Machairodont adaptations and affinities of the
Holarctic late Miocene homotherin Machairodus (Mammalia, Carnivora, Felidae): the case of Machairodus catocopis Cope, 1887. Journal of Vertebrate Paleontology 33:5, 1202-1213
You can check it in the JVP page: