BIOL 322 Lecture Notes - Lecture 10: Carbon-14, Carbon-12, Archaeopteryx
Document Summary
How is the age of a fossil calculated: throughout life, organisms accumulate carbon-14, a radioactive isotope, along with stable carbon-12, living organisms have a constant amount of carbon-14, after the organism dies, no more carbon-12 or carbon- 14 is added: however, carbon-14 decays at a constant rate, leaves the organism as nitrogen, during any 5730-year period, amount of carbon-14 in the organism divides in half, in other words, the half-life of carbon-14 is 5730 years. Transition fossils: but has feathers, all dinosaur , feather cover forelimbs, more feathers, now on forelimbs, flight, archaeopteryx, ancient wing , around 150 million years ago, reptiles, birds. Tetrapod evolution: 20 million years, sea, ansition period, land, tiktaalik fossil, can live in the sea and on land, could pull self on land, could breath under water. Divergent evolution: monkey, whale, pig, bird, adapting over time for different purposes, bones that have homology, vertebrate animals, but different bone structures.
