ANT 1 Lecture Notes - Lecture 25: Quadrupedalism, Aegyptopithecus, Sivapithecus
Document Summary
Flowering plants spread -> primates take advantage of new niches. Fossil formation: covered quickly, sediment builds up. Inferred phylogeny will be based on which species get fossilized. If different species had fossilized, we might infer different phylogeny. Finding intermediate specimens will just mean 2 gaps instead of 1. Missing data causes us to underestimate the age of a species. We can interpret relative time based on the layers (strata) in rocks or soils. Certain elements have naturally occurring radioactive varieties. Radioactive varieties are unstable, so they decay into other elements. Half-life: an average amount of time until half the atoms in sample have decayed. Volcanic rocks contain both potassium & argon. Argon atoms exited & exit rock as gas. Potassium-argon ratio fives time since rock cooled. Rift valley of eastern africa has useful geological features for paleontologists. Pulling apart = exposure of deeper sediments. Primate origins - paleocene (>65 ma in cretaceous)
