ROGEL RIAN JO T. AGRAVANTE

BART'S DINOSAUR PAGE Dinosaurs were land archosaurs with an upright gait. (upright gait,sprawling gait) Dinosaurs were reptiles that evolved an upright gait similar to that of mammals, ie their legs were straight, perpendicular to the ground and supported the weight of the body so that they could walk or run more easily. Other reptiles and modern lizards have a sprawling gait. Dinosaurs ruled the Earth for 160 million years. Archosaurs (literally 'ruling lizards') are a large group of reptiles that appeared about 250 million years ago. As well as giving rise to the dinosaurs, they include non-dinosaur groups such as the pterosaurs (flying reptiles), now extinct, and crocodiles whose descendants still live today. As well as these non-dinosaur archosaurs there were many other ancient reptiles that are often wrongly called dinosaurs. Other ancient reptiles often called dinosaurs include Plesiosaurs ('near lizards'), sea-living reptiles. Ichthyosaurs ('fish lizards'), dolphin-like sea reptiles. Mosasaurs ('Meuse lizards'), sea-living lizards. The Museum contains an impressive display of these fossil marine reptiles. Synapsids (mammal-like reptiles), an entirely different lineage of ancient reptiles from which mammals evolved. These mostly lived before the dinosaurs. See more synapsids in the Museum's Picture Library.