What really struck me in that class however, was how very very strange - almost hideously distorted - the human design is compared to most other vertebrates - that weird gigantic skull, that strange bipedal stance, very, very odd.

Love your blog.

Your portrayal of the thylacine is almost perfect In my eyes. The big problem with most illustrations of Thylacines is that they portray it with yellowish, dingo like fur, when in reality they possessed a gray-brown pelage as a background to their stripes. This is a common trip up on the fact that most specimens of thylacine skin are sun or light damaged from years of display, properly preserved skins show it’s true colour. So I’m saying that I haven’t come upon such an accurate colouration of thylacine pelage, In a general atmosphere today that the urban-myth guise of the thylacine portrays it differently to what it really looked like.

Kudos to you sir!

Tim

In the field of really old mammallian carnivores some get real old. Unfortunately, the article I linked to above does not say if the animal was a placental or marsupial animal. Or even a monotreme, multitubuculate, or a triconodont. All that is said is that it is a mammal.

If it is a eutherian (placental) mammal it’s most likely an early condylarth. Known early Jurassic primates were arboreal, and groups such as creodonts, carnivores, and ungulates were post Jurassic. And which type of condylth it might be isn’t stated, probably because we don’t know enough about Jurassic condylarths to make a definitive identification

One thing we do know about condylarths is that it was not a monophyletic group (like snakes), but a paraphyletic group (like thecodonts). That is, a grabbag of beasties lumped into a single group because they just happen to have similar features. (Such as the way teeth are set into the lower jaw. BTW, did you know that humans could be classified as thecodonts? )

So the Jurassic otter-beaver might be a eutherian. If a eutherian most likely one of the condylarth groups. Which of the groups we now call ungulates is anybody’s guess. Or it might be part of a condylarth group ancestral to creodonts or carnivores, though not everybody agrees that those two groups are descendent from condylarth ancestors.

To complicate the history of ungulate carnivores, keep in mind that such as pachyaena are now considered an omnivore, and more a late condylarth than an early ungulate. Even the later mesonychids are thought to be more scavengers than active predators.

As for the short legs of the thylacine and pachyaena, that is a forest trait. True coursing animals evolved on open grasslands; a condition not really possible until the spread of the grasses around 55 million years ago. Forest dwellers need mobility more than speed, so short legs had an advantage. It’s also harder to work up a good head of speed what with trees and bushes, and deadfall in the way, so predators didn’t need to work up a good head of speed either. Now add in that fact that before the appearance of widespread grasslands forest and brush could spread farther than they can now. In short, forest and brush tended to be more varied and more open than they are now. It meant that on the average ancient forests had a greater carrying capacity per square mile than they do know. All this coming together to mean that catching prey was a lot easier back then.

You’ll note that the only short-legged groups of predators (bears, mustelids, etc) are forest dwellers, and for the most part omnivorous. The same holds true for short-legged felids and canids, such as the clouded leopard or east Asia’s racoon dog. The advanced carnivores, cats and dogs, are log-legged animals, indicatitng an origin out on the grass lands.

Finally, to bring this lengthy comment to a close, keep in mind the Earth did have a substantial, even dominant group of bipedal predators. A group which ranged from the Late Permian to the end of the Cretaceous, and which has been placed in at least two orders, and which just might warrent a third. This group belonging first to the late pre-saurischian thecodonts, then to the saurischian dinosaurs. And the last few genera may someday be listed among aves.

http://www.austmus.gov.au/thylacine/index.htm