BIOLOGY 1M03 Lecture Notes - Lecture 9: Radiometric Dating, Paleozoic, Cenozoic
12 Oct 2016
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Biology 1m03- chapter 27: phylogenies and the history of life part 2. Four limitations to the fossil record are recognized, as biases: habitat, taxonomic, temporal, and abundance. Habitat bias occurs because organisms that live in areas where sediments actively are being deposited are more likely to form fossils than are organisms that live in other habitats. Taxonomic bias occurs because some organisms (e. g. , those with shells or bones) are more likely to decay slowly and leave fossil evidence. Temporal bias occurs because more-recent fossils are more common than are ancient fossils. Abundance bias occurs because organisms that are abundant, widespread, and present on earth for long time periods leave evidence much more often than do species that are rare, local, or ephemeral. Major events in evolutionary history are marked on the timeline shown in figure 27. 8, which has been broken into 4 segments. Time intervals were determined on the basis of rock formations or fossilized organisms, then with radiometric dating.
