GEOL 1020 Lecture Notes - Lecture 7: Chitin, Stephen Jay Gould, Bumblebee
7 Dec 2017
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Trace fossils: tracks, trails, burrows, etc. left behind by animal activity. Number of living eukaryotic species on earth. ~1. 9 million named species of organism (as of 2009); >half are insects. 99% of all known animal species are smaller than a bumble bee! >99% of all plant and animal species that have ever lived are already extinct, and most leave no fossils. (stephen jay gould, paleontologist; About 250,000 fossil species have been described by paleontologists for the phanerozoic eon. Diagenesis: any chemical, physical, or biological change undergone by a sediment (or organism) after its initial deposition (or death) The most important step in fossil formation is rapid burial in absence of scavengers and oxygen. Marine environments because sediment is being deposited there (as opposed to being eroded) Most marine environments are depositional (meaning sediment accumulates there), whereas . Most terrestrial environments are dominated by erosion and net sediment loss, resulting in gaps in the fossil record.
