Allosaurus ( “strange dinosaur” ) are carnivorous dinosaurs from theropod family, they lived in Jurassic Period 155 – 145 millions years ago. They was named so, because their vertebrae was very different from vertebrae of other dinosaurs, that was know at that time. Allosaurus reached 11 – 12 m in length and 2,5 – 3 m in height ; their maximal weight was 1 – 2 tons. They were biggest predators of their time and hunted on plant-eating dinosaurs, like stegosaurus and iguanodons. Fossils of allosaurus were found in North America, Europe, Africa and Australia; in total there were found 60 fossilized skeletons of allosaurus. First almost complete skeleton of allosaurus was found by farmer M. P. Felch in 1883 year in Colorado, USA. Dinosaur was described first time by paleontologist O. C. Marsh in 1877 year.
They moved on their 2 legs, their forelegs was small and mainly used for hunting. They were able to run fast on their legs, despite their big size and weight, because there were found lots of allosaurus skeletons with ribs, that were broken during falls at high speed running. Also, their vertebrae had special holes, that allowed them to breath through skin at high physical exercise; modern birds also has such adaptations in their skeletons. Probably, allosaurus lived and hunted in groups, because there are lots of their fossilized footprints found together. Their brain was big relative to their body size; and allosaurus was able to perform social interactions and care about their youth. Their inner ear was relatively big and they was able to perceive low frequencies; but they had problems in perceiving high frequencies. Their smelling was developed to high level and they was able to use it for hunting and to determine other animals of their kind.