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Re: Phorusrhacids killing large mammals in National Geographic Channel

> They don't (much) now, though wolves, arctic foxes, and brown bears
> interact with polar bears in modern faunal assemblages.  During the
> mammoth steppe period, though, when the polar bears must have been
> living in a different way than they now do -- I don't believe that
> anyone's suggested that, as a species, polar bears are only as old as
> post-continental-glaciation pack ice --

No, but they are fairly young compared to many of those other species
- only about 200 ky, with a shift away from a brown-bear-style diet
only about ~30 kya. At least, according to

But point taken. Hm . . . I know that tigers were apparently present
in Berginia before the ice corridor opened up - I wonder if they ever
interacted with polar bears in the mammoth steppe environ.

> at least some parts of that list.  There are even a few wild examples of
> polar bear/brown bear hybrids.

According to the biological species concept, polar bears *are* brown
bears. :*  (Or some brown bear populations are actually polar bears, I

> Coyotes are in a pretty seamless genetic continuum with wolves.

I mean ecologically, since large jackals and small coyotes are about
the same size.

And I thought coyotes were the best at keeping pretty distinct,
compared to gray/eastern/red wolf populations (which do still pick up
coyote genes regularly, much more so than the reverse).

> So far as can be told from the extant examples, wolves have either a
> great deal of regional variation in one very plastic species, or the
> various species are all quite young.  The big ones displace the little
> ones in an environment with large ungulate prey; the little ones spread
> due to human extirpation of the big ones.  But there is no strong
> evidence that they're all distinct species and good evidence -- lots of
> interbreeding -- that they're not.

I suppose that's probably a complex and contentious issue in some
circles. At any rate, I was mainly pointing out that the eastern
wolves are more distinctive than the Great Plains variety, relative to
any "baseline." And *C. dirus* appears pretty distinct, also, AFAIK.

>> If we're talking about relatively recent ecosystems, we should
>> probably also be including *Meganteron*, *Homotherium*,
>> *Pachycrocuta*, Eurasian jaguars, and maybe even *Dinofelis* and
>> *Agriotherium* in the discussion of Old World predator guilds - not to
>> mention *Chasmaporthetes* across Africa and the Holarctic.
> I'm not sure all of that stack are all going to be in the same ecosystem
> at the same time, but yeah, it's not a short list.

No, in fact they would not all be found together (that'd be fun to
watch, though). I was just pointing out that they'd have to be
considered for various places and times that can be thought of as
"recent," and therefore considered in the general discussion of that

IIRC, lions, leopards, cheetahs, jaguars, *Dinofelis*, *Meganteron*,
*Homotherium*, and spotted hyenas all broadly coexisted for a while in
Africa, though. Man.

> Clovis people gotta eat!

They could've eaten berries and grubs like sensible omnivores.

Or each other. :P

(The really ironic part is that, according to some research somewhere,
it's more economical to hunt small game. You get more calories per
unit of time and energy expended, and at lower risk. But tribal
cultures socially - and reproductively - reward the hunters who
surmount the risks to bring back the biggest kills. So spread the
word: macho posturing killed the mammoths!)

> This is an annoyingly plausible hypothesis.
> My own preferred hypothesis is that it was a good deal more social from
> a younger age, and did an ontogenetic niche progression.

I've heard that concept before, and frankly it seems to make a lot of
sense. Probably other factors involved too, of course. I wonder if
there are any studies correlating large-theropod diversity and the
presence of a given prey type (sauropods, large ornithopods, etc).

> Hell Creek might, but I don't know.

Hm. I know I've seen that proposed, but not in any recent work. It
might make sense of that situation.