Metailurus or Yoshi? Meet the real cats behind the names

We all know that there are the “normal” or conical toothed cats, and the sabertoothed cats.
But there is a group of fossil cats, sometimes called the “false sabertooths”, which look intemediate between the two, in a confusing and, I would say, annoying way. Their “intermediate-ness” is annoying because it has created a lot of confusion regarding their exact affinities.
These cats, including among others the genera Metailurus and Dinofelis, are known as “Metailurins” (if you think they are a tribe) or “Metailurines” (for those who consider them a subfamily). For some paleontologists, they are true sabertooth cats, that is, they belong in the subfamily Machairodontinae, even if the “sabertooth features” are only moderately expressed in them. But for other specialists, Metailurines are just conical-toothed cats (and thus members of the subfamily Felinae) which have converged to a moderate degree with true sabertoths… Who is right? An overview of the published evidence has convinced me that the arguments in favour of their “sabertoothedness” are more convincing, and so in my book “Sabertooth” I include them in the machairodontine ranks, but not without making the customary cautions.
This is a less than satisfactory state of affairs, but things get even more frustrating when researchers find that the names applied to some metailurin species don’t fit the strict rules of nomenclature. It is hard enough for the layman, and even for the specialist, to keep track of the formal changes in the names of fossil species over the years, but as new fossils throw new light on the anatomy of animal groups, there are too many opportunities for the old nomenclatures to come down crumbling and create further confusion.
One such example is the finding of a beautifully preserved skull of a metailurin cat in the Balkans, recently described by Spassov and Geraads ( here is the reference: Spassov and Geraads 2014. A New Felid from the Late Miocene of the Balkans and the Contents of the Genus Metailurus Zdansky, 1924 (Carnivora, Felidae). Journal of Mammalian Evolution)
In principle the skull is very similar to those of metailurin cats of the genus Metailurus, and in particular to the small species that most specialists refer to as Metailurus parvulus. But it differs from previously described skulls in a series of anatomical features that make it similar to, guess what -a cheetah! Yes, the new cat has a domed skull, with a convex dorsal outline and enlarged frontal sinuses, making it different enough from other Metailurus to lead the authors to create a new species name, which (in principle) would make it Metailurus garevskii. This is a relatively small cat, intermediate between a lynx and a cheetah, and thus similar to Metailurus parvulus, and smaller than Metailurus major. But then the authors consider that it is so different from M. major (the type species of the genus, that is the species for which the genus name was originally created) that it indeed deserves to belong in a separate genus, which they name Yoshi. And they think that the new cat is not alone in that genus, because the small M. parvulus is also very different from the big M. major, and more similar to their new species, and in their view the paleontologist Zdansky was wrong to put the two animals together under one genus name to begin with… So they propose that M. parvulus is also part of their new genus Yoshi.
So far so good, but they propose more changes. In their view, the species name M. parvulus was not formally valid, because that name was created for fossils that are incomplete (fragments of mandibles mostly) and not diagnostic enough, so we should all be using the name M. minor, created years later by Zdansky for some nice skull fossils from China…
The result? If we accept the proposal of the paper’s authors, the animal that appears as Metailurus parvulus in my recently published book “Sabertooth”, should now be called Yoshi minor. Is this the right move? May be it is, altough further study may tell otherwise. And in any case, the rules of zoological nomenclature when applied to fossil vertebrates are a source of endless confusion and even embarassment. During the XIX and much of the XX century, paleontologists went in a sort of race to name as many new species as they could, and some times they used pitiful scraps of fossil bone as a justification to create yet another name that would go to their credit. Paleontological curricula were built like that, but later scholars have faced the ungrateful duty of clearing up the mess, and in the meantime, well-loved names (remember Brontosaurus?) have been discredited after long years of use.

But what about the real cats behind these names? They say a picture is worth a thousand words so for now I will just illustrate them here and leave a longer discussion of them for another post!

First, here is my reconstruction of the head of Yoshi garevskii, based on the amazing skull described in the new study. The outline and proportions of the head are indeed cheetah-like, with a marked angle between the nose and the forehead, and the upper canines are so short that their tips would barely be visible in life.

metailurus-yoshi-baja

And here is a reconstruction of the whole body of Metailurus parvulus, actually a combination of the skeletal and life restorations from my book “Sabertooth”

Metailurus-parvulus-skel-and-life transparent baja

If we follow the proposals in the new paper, this animal now needs to be called Yoshi minor. The skeleton, as revealed by a complete specimen from Kerassia (Greece) and several unpublished specimens from China, does indeed resemble the cheetah to some degree in having long and gracile limb bones, although the cursorial (running) adaptations look less extreme, and the forelimbs in particular are considerably shorter. Whether these similarities imply a degree of functional convergence with the cheetah is something that will require careful anatomical studies. But certainly the animal in life would have an elegant, long-limbed appearance quite different from that of the more familiar, powerful sabertooth cats of the Plio-Pleistocene.

For a more complete coverage of the Metailurines, go and read “Sabertooth”! And remember that no matter howe many times we change their names, the real, once living animals are the thing that matters!

Here is a link to the Spassov and Geraads paper:

http://link.springer.com/article/10.1007%2Fs10914-014-9266-5#page-1

Posted on 04/06/2014, in Uncategorized. Bookmark the permalink. Leave a comment.

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