Mapusaurus

Mapusaurus is both one of the most underestimated and one of the most overestimated dinosaurs. Many people claims that it reached 10-11 m long. This is a myth. Look at this:

So, Mapusaurus' lenght was at least 12.2 m. Wikipedia says 10.2 m only because the specimen wich measures 10.2 m in TL is the largest Coria and Currie provided a measurement for. I hope this will debunk that tiny 10-11 m Mapusaurus.

Mapusaurus is often overestimated as well. Many people likes claiming that it's the largest Theropod ever. Their proof? A pubic shaft, wich is 110 % the size of the corresponding part in the Giganotosaurus' holotype. This would make that Mapusaurus almost 14 m long (13.6 m) with an estimated mass of almsot 9 t (8 900 kg), and it would effectively be the largest Theropod. Now I'll explain why I think that isn't wise calling this Mapusaurus specimen the largest Theropod.

We must consider every Mapusaurus specimens. And most of them are under 13 m. The holotype is, for example, between 11 and 12 m long; smaller than both MUCPv-ch1 and "Sue", estimated at 6-7 and 7-8 t respectively. We cannot call Mapusaurus bigger than Giganotosaurus or Tyrannosaurus because of this specimen, since most of the specimens aren't really any bigger.

Plus, I doubt this specimen represnts a such big animal. That Mapusaurus isn't even scaled from a specimen of the same species, but from MUCPv-ch1. Even MUCPv-95, the (in)famous Giganotosaurus' jawbone, is more reliable; at least, we can scale it from a specimen of the same species. I know, Giganotosaurus and Mapusaurus are very close relatives. That doesn't prove anything. Using Giganotosaurus' holotype for scaling that Mapusaurus' specimen size is like using Gorgosaurus for scaling T.rex's size. Look: Let's say that we haven't got any complete T.rex, but just a femur. That femur is 132 cm (like "Sue"'s). We have a complete Gorgosaurus. Its femur measures 105 cm. So T.rex's femur is roughly 26 percent larger. So the whole animal will be expected to be 26 % larger than Gorgosaurus. Gorgosaurus measures 8-9 m in TL. Here are the results:

8*1,26=10,1 m

9*1,26=11,3 m

So "Sue" would be in the 10-11 m range, while we know that it was roughly 12.5 m long. That's because Gorgosaurus is more long legged than Tyrannosaurus, so those animals didn't share their proportions. Now you understand why I don't trust that Mapusaurus specimen, don't you? I think the safest thing to say is a vague "similar in size with Giganotosaurus", or roughly 12-13 meters long.