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Lab 12 Evidences for Evolution 3 types of evidence • Fossil record • Comparative anatomy • Biochemical evidence Fossil record How are fossils dated? First fossils were found in which era? What type of organisms were the first fossils? What are the 3 eras in the geologic time scale? Lab manual exercises will look at which type of fossils appeared in which era. • For table 12-2 use these organisms for examples of specimens from each era. • Cenozoic-angiosperms • Mesozoic-euypterids • Paleozoic –giant club mosses • Note which types of organisms are extinct. Comparative Anatomy • Comparison of homologous structures (synapomorphies) • Analogous structures (homoplastic features) do not indicate evolutionary relatedness • Compare forelimbs of several mammals to the ancestral condition. Discuss the possible reasons for some of the differences seen. • Compare chimp and human skeletons and skulls. Comparison of embryos • Vertebrate embryos share 3 characteristics – post-______ tail – ___________pouches – Mesodermal segments called ______ – Look at chick embryo slides with a dissecting microscope. Try to locate the features that are found in the drawings. At what embryonic stage can these features be seen? Biochemical comparisons • Comparisons of protein sequences, DNA, ribosomal RNA. • More similarities in sequence- more evolutionary relatedness. • Compare similarities of molecule cytochrome c among species • Work on handout which requires you to count the difference in amino acid sequences. Lab Report due next week • Page 160 of lab manual “Lab Review 12” • Questions from cytochrome c handout