EARTH 7 Lecture 18: Earth 7 - Dinosaurs - Lecture 18 Notes
12/7/17
● Review
● Important evolutionary trends within ornithischians
○ Herbivory
○ Defense
○ Sociality
■ Most theropods are carnivores
■ Most sauropods are herbivores
■ Most ornithischians are herbacors
● Carnivores vs. herbivores
○ Meat easy to digest
○ Plants not easy to digest
■ Solutions
● Large belly
● Lots of chewing
○ Predentary bone
○ Low jaw joint
● Scelidosaurus
○ Indicates what a common ancestor to stegasaurians and ankylosaurian would
have looked like
○ Described by richard owen its one of the earliest complete fossils
● Earliest groups of ornithiscians are smaller bipel to large and quadrupedal
○ Happens 4 times
■ Stegosaurians - dermal armor, plates
■ Ceratopsians - triceratop like
■ Ornithopods - duck billed dinosaurs
■ Sauropods - long necks
● Stegosaurians
○ Maybe secondary brain?
○ Plate function?
■ For heat regulation - important
● Ankylosaurians
○ Dorsal shield, horns, clubbed tail
○ Convergence with body armor
○ One of the most beautiful fossils found a few years ago
● Stegosaurians flourished first than ankylosaurians
● Cerapods
○ Diastema, uneven enamel thickness
○ Two major groups
■ Ornithopods
● Duck billed dinosaurs
○ Hadrosaurid
Document Summary
Indicates what a common ancestor to stegasaurians and ankylosaurian would have looked like. Described by richard owen its one of the earliest complete fossils. Earliest groups of ornithiscians are smaller bipel to large and quadrupedal. One of the most beautiful fossils found a few years ago. Not maiasaur us because named after the female gender. Did get larger but not large enough to go quadrupedal. Diverse group that used heads as battering rams. Different parts of the body grow at different rates. All ornithiscians dont have lower front teeth. Small and bipedal to large and quad. Ealiest ones are small and bipeal but get larger and quadrupedal. Cable of ligaments to hold up neck. These appear to have replaced other sauropods that began to die out in late jurassic and early cretaceous. Larger size can subsist on low quality food. Looked similar to ancestor of all dinos. Although didn"t have the dinosaur name yet.
