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Description

A selection of carnosaur theropods known as metriacanthosaurids, to scale.

During the Middle to Late Jurassic, the apex terrestrial predator role was dominated by a couple of large theropod groups, namely ceratosaurs, megalosaurs and allosauroids. Compared to the others, ceratosaurs were actually a minor part of the Jurassic carnivores, but they would go on to reach greater heights during the Cretaceous in the southern continents (see Horned rulers of Gondwana - Abelisaurids ). Historically considered a waste-basket clade for poorly known large theropods, the megalosaurs were a valid group of large skulled theropods concentrated in Europe with just a handful of species reaching Africa, China and North America. However it was the famous allosauroids which ranged widely across North America, South America, Asia and Europe (possibly also Africa). Like the ceratosaurs, allosauroids would also rule across South America and Africa later on during the Cretaceous. One small family that was far less famous than Allosaurus were the largely Asian metriacanthosaurids.

Metriacanthosaurids had a general carnosaur build with the addition of moderately tall spines along the back. The group almost certainly evolved in East Asia with most fossils having been found in China, while several species are known from England and Thailand. Early forms, such as Xuanhanosaurus, were relatively small and had robust forearms (early descriptions suggested it was quadrupedal). Due to limited remains, the taxonomy of some species has flipped around. Metriacanthosaurus was considered a species of Megalosaurus and Altispinax, while Yangchuanosaurus was also lumped into the same genus. Sharing the same habitat as large sauropods and stegosaurs, the large Yangchuanosaurus was evidently capable of hunting big prey, but whether in hunted in groups is unknown. This behaviour is widely suggested for other allosaurids.
Metriacanthosaurids survived into the Early Cretaceous (Siamotyrannus) but likely faced new competition in Asia from the arrival of the tyrannosaurs.

Description

A selection of carnosaur theropods known as metriacanthosaurids, to scale.

During the Middle to Late Jurassic, the apex terrestrial predator role was dominated by a couple of large theropod groups, namely ceratosaurs, megalosaurs and allosauroids. Compared to the others, ceratosaurs were actually a minor part of the Jurassic carnivores, but they would go on to reach greater heights during the Cretaceous in the southern continents (see Horned rulers of Gondwana - Abelisaurids ). Historically considered a waste-basket clade for poorly known large theropods, the megalosaurs were a valid group of large skulled theropods concentrated in Europe with just a handful of species reaching Africa, China and North America. However it was the famous allosauroids which ranged widely across North America, South America, Asia and Europe (possibly also Africa). Like the ceratosaurs, allosauroids would also rule across South America and Africa later on during the Cretaceous. One small family that was far less famous than Allosaurus were the largely Asian metriacanthosaurids.

Metriacanthosaurids had a general carnosaur build with the addition of moderately tall spines along the back. The group almost certainly evolved in East Asia with most fossils having been found in China, while several species are known from England and Thailand. Early forms, such as Xuanhanosaurus, were relatively small and had robust forearms (early descriptions suggested it was quadrupedal). Due to limited remains, the taxonomy of some species has flipped around. Metriacanthosaurus was considered a species of Megalosaurus and Altispinax, while Yangchuanosaurus was also lumped into the same genus. Sharing the same habitat as large sauropods and stegosaurs, the large Yangchuanosaurus was evidently capable of hunting big prey, but whether in hunted in groups is unknown. This behaviour is widely suggested for other allosaurids.
Metriacanthosaurids survived into the Early Cretaceous (Siamotyrannus) but likely faced new competition in Asia from the arrival of the tyrannosaurs.