#and NOW you can talk about Gigantoraptor

[saritapaleo]

Now that I’ve introduced the major groups of Oviraptorosaurs (oviraptorids, caenognathids, and outliers), we can begin to talk about their diversity. And we simply must begin with the largest oviraptorosaur: the truly gigantic caenognathid Gigantoraptor erlianensis.

Gigantoraptor was 8 metres (26 ft) long and weighed around 2 metric tons. Unusual for giant theropods, it also had long limbs, with both its tibia and femur measuring over 1 m (3.3 ft) long. Giant ovoraptorosaurian eggs have been found that were likely laid by Gigantoraptor or similar, yet unknown giant caenognathids. These eggs were placed in a ring around their nest, with no eggs in the center, likely to mimimize the chance of the parents crushing their own eggs under their weight. Gigantoraptor’s toothless, shearing beak indicates a herbivorous or omnivorous diet, similar to other oviraptorosaurs, however it could have also engaged in carnivory occasionally. And who would stop it?

Living in the Iren Dabasu Formation of Late Cretaceous Mongolia, Gigantoraptor was one of the largest dinosaurs in its humid, floodplain, river valley habitat. The largest predator (that has been found so far) was the tyrannosauroid Alectrosaurus, a 5 to 6 meter (16 to 20 ft) long pursuit predator that was probably about as tall as a human. If Alectrosaurus had any hope of catching a Gigantoraptor, it would have had to hunt in a group and target young and weak individuals. But there were plenty of other species they could have hunted, most of them far easier prey than Gigantoraptor. These could have included the ornithopods Bactrosaurus and Gilmoreosaurus and the speedy ornithomimosaur Archaeornithomimus. Other, smaller, oviraptorosaurs lived alongside Gigantoraptor, including the caenognathid Caenagnathasia and indeterminate avimimids. The therizinosauroids Erliansaurus and Neimongosaurus would have also shared the habitat. The only thing larger than Gigantoraptor in the Iren Dabasu Formation was the 9 meter (30 ft) long titanosaur Sonidosaurus.

While Gigantoraptor is the largest oviraptorosaur I’ll be covering, other giant species did exist. Giant oviraptorosaur nests and eggs have been found in multiple formations, including within North America, but the remains of adults have yet to be found…

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