Re: Phorusrhacids killing large mammals in National Geographic Channel

[Augusto Haro <augustoharo@gmail.com>]

>> The largest representatives of the native South American mammalian
>> herbivores are Plio-Pleistocene, as far as I know, so the previous
>> South American fauna had fewer large representatives.
>
> Yeah, but still generally good-sized animals, regardless. At least
> deer-sized, IIRC.

I do not know which one was the largest pre-Pliocene South American
mammal, but pre-Pliocene Borhyaena was considered as larger than human
on the basis of the skull, but approximately 30 kg. on the basis of
the whole skeleton. The head of these beasts seem to have been very
large compared to placentals, and if a few 30 kg. African wild dog can
kill a zebra, I bet the much more massive head and musculature of
Borhyaena may have permitted this beast to prey upon large and not so
fast items (there was plenty of sloth species in South America,
although these would put a fight with their massive arms, claws and
large caniniforms).

> Seriemas can fly, no? That seems like it could be quite important. Not
> sure about differences in nesting habits, but that could be relevant
> too. And there were phorusrhacids not really all that much bigger than
> seriemas, IIRC, so maybe they *were* outcompeted/had their eggs eaten
> by by canids/felids/mustelids.

There is an argument about whether or not the smaller phorusrhacids,
such as Psilopterus, with relatively longer wings, can or not fly.
Seriemas do not perform long flights, however. They are said to be
helped climbing by the laterally compressed claws, which are also
present in Phorusrhacids. So perhaps they were not very different to
the smaller phorusrhacids in habits.