GEOL 008 Lecture 16: 16 - The Remaining Saurischians
Document Summary
The pubis points bach, against the ischium. Ornithischians - all closely related to iguanodon. Saurischians - sauropods (apatosaurus) + theropods (t rex/ birds) Ornithoscelida (bird legs) - ornithischians + theropods. Based on computer analysis of many traits of early triassic dinos. Phytodinosauria (plant eating dino) - orthiscians + sauropods. Proposed in the 80s based on herbivore characters. Traditional model (theropods are saurischia?) maybe wrong. Late triassic to end cretaceous thrived for 165 million years. Still bipedal, grasping hands, large finger 1. Transition from leaf shaped teeth to simple spoon shaped teeth. Dependent on gastroliths and gut bacteria to break down plants. Difficult to pump blood up a long neck. Most other amniotes have vertical necks even if they dont look it. Holding a neck horizontal will use a lot more energy. Nares up high,connected, almost as big as orbit. Modern atmosphere less productive, less oxygen, less nutritious plants than mesozoic. Live birth, very long gestation; low rate of reproduction.
