The Evolution of Feliform Saber-Tooth Skull Shape

Finally back for some discussion of saber-tooth cats, nimravids, and barbourofelids. There are two complementary articles that appeared almost simultaneously regarding the shape of the saber-tooth skull. Skull shape was examined by mapping various landmarks on different species’ skulls and measuring the change in position of these landmarks compared to average values.

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Thylacoleo, a Unique Extinct “Super-Predator”

WHILE MANY NICHES are ever-present in vertebrate-dominated ecosystems, sometimes we find an extinct group that was unique in some way. At various times in the past carnivores have evolved saber-teeth, but currently there are no saber-toothed predators (although the clouded leopard may be working on it). In a previous post I mentioned Simocyon, a cursorial generalized carnivore that retained arboriality in order to escape from larger predators, including the saber-toothed cats. Today I will write about Thylacoleo carnifex, the so-called marsupial lion.

Pop Science Journalists Cause Mental Anguish

ABOUT A MONTH ago I reported on a better-resolution metazoan tree of life. This week the article came out in Nature, and has been followed by a storm of really bad reporting:

Earth’s first animal was the ocean-drifting comb jelly, not the simple sponge, according to a new find that has shocked scientists who didn’t imagine the earliest critter could be so complex.

What’s wrong with this? Basically, the study showed that the line leading to the ctenophores may have diverged before the other metazoan lineages. Stating comb jellies were the “first animal” is going to lead to people thinking that all animals evolved from comb jellies! Some other stories on this article do specify the ctenophore lineage diverged first, which is somewhat less misleading. However, this lineage diverging first does not mean modern ctenophores were there at the time. We might also consider that at that divergence the other lineage produced led eventually to humans, and we certainly were not swimming about in the ocean with the ctenophores waiting for land-living plants and animals to evolve so we could get out and dry off. Modern humans are much different from their early ancestors, and modern ctenophores may be as well.

Simocyon, a Unique Extinct Carnivore

THERE ARE certain niches that seem to be filled by one species or another at any time period. In my recent post on mammalian evolution, for instance, I mentioned Castorocauda, a Jurassic mammaliform that seems to have fit into the niche now occupied by beavers or otters. But occasionally we run across an animal that seems to be adapted for a unique role in its ecosystem. One of these animals is Simocyon. This is a puma-sized caniform that lived about 14 million years ago, and died out by four million years ago. Simocyon has a variety of unusual adaptations.

Big Cats in Britain

ALL SABER-TOOTH and big cat fans should step over to Tetrapod Zoology, where Darren Naish reports on the Big Cats in Britain conference. The first part of this two-part survey discusses the possible late survival of Homotherium latidens, a saber-toothed cat, as well as extinct leopards and lions. The second talks about extinct pumas in Europe and cheetahs in America, geographical distributions that we are not accustomed to for these cats.

The Diet of Saber-Toothed Cats

ORIGINALLY PEOPLE thought that the long canines of saber-toothed cats were intended to pierce the thick skin of mammoths and were used to inflict gaping wounds. However, recent modeling suggests that repeated biting of struggling prey would result in breaking the saber-cats’ teeth, and that the fangs were used in a single neck bite on pinned prey, severing major blood vessels and quickly resulting in death.¹ As the other two major groups of saber-tooth carnivores, Nimravidae and Barbourofelidae, have been extinct for millions of years, we will probably have to determine their diet based upon deduction. Fortunately the saber-toothed felids have been extinct for only tens of thousands of years, which is practically yesterday! We have some evidence of their diet in a cave that served as den for Homotherium and in the bones of Smilodon preserved in the La Brea tar pits.

The Face of a Saber-tooth

I HAD PLANNED on writing about protostomes and deuterostomes today, but Christopher Taylor of Catalogue of Organisms mentioned some people think protostomes evolved from deuterostomes, which I had not heard before. So the deuterostomes are on hold until I can read about this idea, probably Monday. Which is fine with me because the alternative topic is the Barbourofelidae!

We are dependent on paleontologists for an accurate reconstruction of a fossil skeleton, but even once that is done it can be hard for us to imagine what the animal really looked like unless an expert steps in and reconstructs the details. From looking at the skulls of the saber-toothed nimravids, barbourifelids, and true cat machairodontids, we know that they were predators with really long canines. But what did they really look like?

I was lucky enough to find a paper which attempts to reconstruct Barbourofelid fricki‘s face.¹ To do this the authors used skull structure and muscle attachment scars, with reference to modern cats. While the barbourofelids are not felids, the two groups had superficially similar body plans allowing some comparisons to be made. Many of the conclusions from modeling this species can probably be generalized to other dirk-toothed predators.

Nimravidae: Definitely Not Cats

SINCE I STARTED this blog I have received an increasing number of hits from search engines. Unsurprisingly, one of the topics funneling people this way is the Nimravidae. My entry on the Dinictis skull replica found at Bone Clones has received the most hits overall since I started this blog. Unfortunately, there is not really much information about nimravids available without some digging, and very little on the open web. So here I will pull together everything I can currently get my hands on!

A beautiful nimravid skull!

TODAY I WAS poking about at Bone Clones (their slogan is “Only Mother Nature Does it Better”, but I think it should be “Because Everyone Should Have a Replica of the Skull of a Conquistador Who Took an Axe to the Brain“) and found a beautiful replica of a nimravid skull, namely Dinictis.