I've been looking for information on Terrorbirds (Phorusrhacids,) these birds were the top land predators in South America until about two million years ago. Ranging from 18-1,500 lbs depending on the species, these animals became extinct not long after the North American continent bridged to theirs. It is assumed that North American carnivores are responsible for their extinction (namely cats species like jaguars and saber-tooths.) I'm not so sure though, I can't see a 200-300 lb jaguar taking on a half ton terror bird myself, especially if they hunted in groups as it is assumed (most cats are solitary predators.)


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not all cats are solitary hunters, some are, but some arent, sabre tooth cats are believed to hunt in packs just like lion females, so any giant bird didnt stand against a chance

Or maybe its that they were just outcompeted...

ya after north america joined up with south america, the big cats from north america would have made life harder for the terror birds since the big cats would have been hunting their food down and at the same time them to

Not just that, their prey could be outcompeted also..

Does anyone know what exactly their prey was? They seem to be well built effecient predators... the raptors of their day. I might almost have expected them to immigrate up here. Have their been any finds north of Central America? Are their any relatives still roaming South America?

small "horses"

This would have been their prey


Macrauchenia
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I remember those "elephant deer" from walking with prehistoric beast. They showed a sabertooth stealing a kill from a terror bird too. The terror bird just ran off like a sissy, what was that all about It didn't go into much detail about their social habits or their preditation habits. From what I've read about them they were cheetah fast where as a sabertooth is considered more a ambush hunter like a leopard, I hadn't heard that they hunted in groups or that they were social cats like lions. I was taught that the social structure of lions is kind of an anomaly in the cat family, and the social hierarchy is more aligned with that of herbivorous herd animals than that of other social predators. That said, putting sabertooths in the niche of lions and terror birds in the niche of cheetahs, shouldn't they be able to coexist in a common habitat?

Possibly...They would compete for food although...

Another possibly is that new species introduced to S America were adept at raiding terrorbird nests and stealing eggs or killing the young? Thus a gradual decline due to less successful reproduction?

Much like rats introduced to islands can quickly decimate bird populations today.

Well, there were no human populations to introduce an invasive species I don't think your thoery is correct.

well i wouldnt say its incorrect but not worded right.. i mean if north an south america joined up then NA predators would have new land to roam. but your right no human populations so were not at fault for this one lol.