Saurischian dinosaurs

Carnosaurids

The name 'carnosaur' has historically been used as a grouping for several of the large meat-eating dinosaurs - spinosaurids, megalosaurids and tyrannosaurids, but modern cladistic analysis now puts many of the animals that were traditionally considered as carnosaurs in different groups. The Carnosauria in its accurate scientific sense now refers to Allosaurus and its close relatives like Acrocanthosaurus and Archarodontosaurus.

Allosaurus lived in the Late Jurassic period, and its remains have been found in North America, Australia, Africa and Asia. The first Allosaurus bones were found in 1869 in Colorado. Allosaurus was a large carnivore up to 35 feet long and weighing about 1.5 tons. It walked on two legs and its heavy body was balanced by a long, deep, tail. Allosaurus had powerful hind limbs with clawed feet; and it also had short three-fingered forelimbs with large, sharp claws. The top of the head had bony ridges and bumps, and the jaws held serrated, blade-like teeth. The jaws were hinged like snake's jaws, so that Allosaurus could swallow enormous pieces of meat.

Acrocanthosaurus or 'high spined reptile' was a flesh-eating dinosaur related to Allosaurus. It lived in the Early Cretaceous period, and was found in 1950 in Oklahoma and later in Texas. Acrocanthosaurus was 40 ft long and weighed between 2-3 tons. Spines along its backbone formed a ridge or low sail that ran the length of the dinosaur from neck to tail.