User:Pengyuli2019/sandbox
From Wikipedia, the free encyclopedia
Allosauroidea is a superfamily or clade of theropod dinosaurs which contains four families — the Metriacanthosauridae, Allosauridae, Carcharodontosauridae, and Neovenatoridae. Allosauroids were the first giant taxa, with weights exceeding 2 tons, of the theropods. They, along with members of the clade Megalosauroidea, were large predators that were active during the Middle Jurassic to Late Cretaceous periods.[2] The most famous and best understood allosauroid is the North American genus Allosaurus.
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Allosaurus fragilis skull, San Diego Natural History Museum | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | Theropoda |
Clade: | †Carnosauria |
Superfamily: | †Allosauroidea Marsh, 1878 |
Type species | |
†Allosaurus fragilis Marsh, 1877 | |
Subgroups[1] | |
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The oldest-known allosauroid, Shidaisaurus jinae, appeared in the early Middle Jurassic (probably Bajocian stage) of China. The last known definitive surviving members of the group died out around 93 million years ago in Asia (Shaochilong) and South America (Mapusaurus), though the megaraptorans may belong to the group as well. Additional, but highly fragmentary, remains probably belonging to carcharodontosaurids have been found from the Late Maastrichtian (70-66 Ma ago) in Brazil.[3]
Allosauroids had long, narrow skulls, large orbits, three-fingered hands, and usually had "horns" or ornamental crests on their heads. Although allosauroids vary in size, they maintain a similar center of mass and hip position on their body.[4] Allosauroids also exhibit reptilian-style immune systems, based off of examining injuries and infections on their bones. It is possible that allosauroids were social animals, as many remains of allosauroids have been found in close proximity to each other.[5]