GEO 103 Lecture 28: Evolution in Mesozoic
28 Apr 2017
School
Department
Course
Professor
Document Summary
Range in size from <1 m to 15m long. Sharp teeth and fed on fish and other marine organisms. 3 to 6m long (rarely longer up to 15m) Both short-necked (bottom feeders) and long-necked (swimming) species. May have ventured onto land perhaps to lay eggs. Late cretaceous marine lizards - related to komodo dragon or monitor lizard. Predators feeding off fish, birds, and other marine organisms. Mostly < 3m long but rarely, eg. tylosaurus up to 9m. Certain skeletal features - eg. way jaw articulates with skull. But birds have feathers and reptiles have scaly tough beaded skins. Feature impressions found in jurassic therapod-like (saurischian!) creatures - archaeopteryx. Fused clavicle wishbone and feathers make this a bird. Other features - reptilian teeth, clawed wings - more like dinosaurs. However, most (but not all) therapods are younger (cretaceous) Not resolved if archaeopteryx is ancestor to birds or separate line that died out. Other possible candidates and geological record very incomplete.
