big carnivores

Rubecula

Adam Khor

T. rex one of the smallest predatory dinosaurs of its time? Nonsense. As far as we know, T. rex was the biggest predatory dinosaur of its time and region. All of the predatory dinosaurs in the same size range that we know about belong to earlier times and different regions. 

The carcharodontosaurs are looking more and more like they could actually be one single genus with several known species. Mapusaurus and Giganotosaurus could very well be classified into Carcharodontosaurus, as they are from about the same time as the African species and the differences between them are minimal. 

Same with Oxalaia; hard to tell since it's actually just a measly fragment, but it looks almost identical to Spinosaurus, which lived at about the same time. Seeing as Spinosaurus appears to have been more aquatic than any other giant theropod known, it wouldn´t be a stretch to imagine it swimming long distances, maybe along coasts, and becoming very widespread, like crocodiles.

Rubecula

T. rex one of the smallest predatory dinosaurs

Yes this initial comment made me blink a bit.

Adam Khor

It is a shame that the supposedly huge abelisaurs found in Kenya haven´t been described yet...

Rubecula

Adam Khor

Abelisaurus comahuensis is indeed known from a skull only, but it could be that we have more material of genus Abelisaurus than we usually realize. 

There's been suggestion that Aucasaurus garridoi actually belongs to Abelisaurus; it lived at the same time and in the same region, and anatomically it is almost identical to Abelisaurus. The one reason it wasn´t clasified in the same genus right away is that it's about half the estimated size of the original A. comahuensis specimen, and its skeleton shows that it was already fully grown. This doesn´t mean, however, that it couldn´t be a second, smaller species of Abelisaurus, and that they both coexisted the way say, tigers and leopards do, hunting different prey and overall avoiding competition. 
(Alternatively, there could be some crazy sexual dimorphism going on). 




Also, there is the recent discovery in Bolivia of footprints attributed to Abelisaurus. The prints are 1.2 meters wide suggesting a monstrous theropod 12 or 13 meters long. 



If the prints are really from Abelisaurus (or Carnotaurus as has also been suggested), then this would be proof that abelisaurs reached sizes comparable to T. rex and we just haven´t found the big ones. That being said I have no idea how the paleontologists reached the conclusion that the prints belonged to abelisaurs, and not to say, carcharodontosaurs, which were also present in South America at the time and are known for their huge size.

Rubecula

sorry for misuse of the dino word here.

jaxxx

Rubecula wrote: »

T. rex one of the smallest predatory dinosaurs

Yes this initial comment made me blink a bit.

I know zip about palaeontology, yet even I know t-rex was one of the top 10, maybe even top 5 largest therapods. Bet you whoever wrote that believes velociraptor was 6 feet tall as well (thanks Jurassic Park movies :mad:)

Rubecula

Adam Khor

Right you are; one of the top three, even, if we merge Giganotosaurus with Carcharodontosaurus (like I said, they are extremely similar and from the same age, so there's a chance they're different species of the same genus). 

Must be said also that even though Carcharodontosaurus and Giganotosaurus are considered to be slightly bigger than T. rex, even this has been disputed. The fact remains that carcharodontosaurs had a relatively slender, laterally compressed torso and a very light weight skull (relatively of course), with large open spaces, whereas T. rex had a very robust body and a heavy, reinforced skull to whitstand its monstrous bite force. This means that even at same lengths, there's a chance T. rex may have been substantially heavier than either Carcharodontosaurus or Giganotosaurus. 



There's always going to be disagreement about mass estimates when it comes to dinosaurs, of course, but just by looking at the skeletons you can see how T. rex is unusually robust even for a giant theropod. 

Giganotosaurus: 






Tyrannosaurus: