PALEO200 Lecture Notes - Lecture 5: Chasmosaurus, Ceratopsia, Rapetosaurus
5 Apr 2016
School
Department
Course
Professor
Document Summary
Palaeontologists would say the egg came before the chicken . Long before chickens evolved, land dwelling animals developed the ability to lay hard- shelled eggs. Very different from fish and amphibians that laid eggs without a protective shell: hard shell. Disadvantage: impact of hard shell on oxygen exchange. Probably developed because land is so dry and can dry out very quickly. As animals became terrestrial, those that laid hard-shelled eggs had an advantage. Dinosaurs inherited this hard-shelled egg laying ability but the shells had to be relatively thin to facilitate oxygen exchange with the air o. Largest eggs were laid by the theropods although sauropods do lay big eggs: although many types of eggs have hard-shelled, they are not a sealed system. Very small pores that allow oxygen in and co2 out. As eggs get bigger, the inside volume gets bigger much faster than the surface area (cube-square law)
