ANTHRO 7 Lecture Notes - Lecture 5: Secondary Forest, Insectivore, Gray Langur
Document Summary
Shared derived characters are the only ones useful for reconstructing. Bipedality in humans and chickens is convergent (independently evolved in the two species): we infer this because humans are among the very few bipedal placental mammals and the details of chicken bipedality are very different. Egg-laying is a shared primitive character (present in the common ancestor of all three species): we infer this because amphibians the outgroup to all three species lay eggs. Lactation is a shared derived character of humans and duck-billed platypus. In nature, it can be difficult to distinguish between ancestral and derived characters. Characters that appear early in development are ancestral. Characters that appear earlier in the fossil record are ancestral. If the trait is able to be detected in the fossil record. Characters that appear in outgroups are ancestral. Using a large number of characters can produce a consensus phylogeny that minimizes the number of convergence and reversals.
