Rachel Neumeier

Fantasy and Young Adult Fantasy Author


Cool early mammals

Over at tor.com, the promised post on seriously cool early mammals. Honestly, you really should click through and take a look. Anybody with their images of “mammals, normal” shaped by modern fauna ought to really enjoy the weird things early mammals did as variations on the theme.

I’ve always loved the prehistoric elephants, who came up with lots of weird ideas besides the trunk. Hard to imagine a jaw like that being a good idea for an elephant, but I guess it was.

One I’d never heard of is Thalassocnus. An aquatic giant sloth, really?

Ordinarily my favorite extinct mammal is always Paraceratherium, because hey, giant rhinos trying out for the giraffe role in the ecosystem, what’s not to love? But today my favorite has to be Amphicyon, because it’s a bit like what one of my black dogs must look like, only of course black dogs are a lot shaggier and, you know, black. And even bigger. And have fiery eyes and black fangs and stuff. Still, this bear-dog type of thing is what I had in mind.


Click through an enjoy! Which one is your favorite?

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2 Comments Cool early mammals

  1. David

    Hi Rachel, I stumbled upon your interesting page by accident while searching images of prehistoric mammals. That’s a cool pic of an Amphicyon. You might want to clarify to your readers that bear-dogs were not part bear and part dog. They were not transitional between dogs and bears, that is, bears did not evolve from dogs, though they had a common ancestor at some point (as do sea lions and bears). They were, if I remember correctly, a specialized offshoot from dogs or close genetic allies of dogs, sort of a subgroup within or related to the true dogs. The ancestry of bears pre-dated the origin of the bear-dogs. So it isn’t a dog, even though “cyon” in its name is Latin for dog. It was named that because it’s doglike. I think its name means “half-dog.” Others in its group were not so large and fearsome as this one. They were Bichon Frise or Kit Fox size. Also, pardon me for saying so, but calling animals like this and the others you mention, such as Paraceratherium and prehistoric elephants “early mammals” is a bit misleading. I consider early mammals to be the ones that lived even before the dinosaurs came into being, 245 million years ago and earlier, the tiny ones that derived from the therapsids, or mammal-like reptiles of the Triassic and the earlier Permian, and persisted in shrewy or ratty form for 180 million years alongside the dinosaurs until they inherited the Earth from them with the advent of the Age of Mammals 65 or so million years ago. Some though, like Repenomamus, reached badger size and preyed on small and baby dinos. Look them up sometime, or maybe you’re already aware of them. Some neat and weird forms among these also, such as the insectivorous flying squirrel-like glider (though of course it was not a squirrel) and Castorocauda, an otter-like animal with a beaverish tail. I’ll check back on your page sometime. I haven’t read any of your books (sorry, I never heard of you before; I’m not a great fan of sword-and-sorcery and mythology type tales, except for Lord of the Rings and The Chronicles of Narnia) but I’ll look them up sometime and maybe try them out. Thank you for your delightful web page and prehistoric mammal commentary. Sincerely, David.

  2. Rachel

    You’re right, David, I should have said “NOT part bear/part dog.” I personally am willing to call any mammal that died out before the modern era “early,” although naturally this blurs together a huge expanse of time. Still, earlier-than-modern seems to me to be a legitimate concept for a casual post.

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