BIOL 1108 Lecture Notes - Lecture 10: Monophyly, Tetrapod, Cosmic Ray
Document Summary
Core concept 3: the fossil record provides direct evidence of evolutionary history. Imprints left behind: not actual animal, tells much info. Imprint left behind from hard bodied animal (snail: not interested in shell pieces left behind. In the atmosphere, neutrons generated by cosmic radiation can collide with 14n to create 14c: 14c that ends up in carbon dioxide can be incorporated into plants through photosynthesis. 14c is next incorporated into animals when they eat the plants: after the plant or animal dies and is buried, its 14c decays to the more stable. 14n: half of the 14c in a fossil turns to 14n in 5730 years. In another 5730 years, half of the remaining 14c decays to 14n and so on. Fossils" (cid:272)o(cid:374)tri(cid:271)utio(cid:374)s to phyloge(cid:374)eti(cid:272) trees i(cid:374)(cid:272)lude: time calibration, records of extinct species, correlation between evolution and earth history. Dinosaur and bird phylogeny: an example of pretty impressive shifts through long periods of ti(cid:373)e i(cid:374) i(cid:374)(cid:272)re(cid:373)e(cid:374)ts!
