Week 4 Notes
Week 4 Notes ENVS 212
Popular in Evolution
Popular in Environmental Science
This 1 page Class Notes was uploaded by Hieu Notetaker on Friday November 6, 2015. The Class Notes belongs to ENVS 212 at Drexel University taught by Dr. Daniel Duran in Summer 2015. Since its upload, it has received 24 views. For similar materials see Evolution in Environmental Science at Drexel University.
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Date Created: 11/06/15
Evolution in the Fossil Record The changes in distribution of land masses and oceans over time have affected the geographic distribution of organisms Continental drift theory supports the record of fossil distributions Catastrophic events have occurred repeatedly including meteorite impacts volcanic eruptions and massive changes in sea levels Climates have changed dramatically Species distributions have changed over time After mass extinction the diversification of higher taxa has sometimes been relatively rapid The number of species the variety of their form and ecological habits all increases Extinct taxa have sometimes been replaced by unrelated ecologically similar taxa The geographic distribution of many taxa have changed greatly over time For example the Camelid family camels originated in North America during Pleistocene and spread out in three ways to south west Asia North Africa and South America Some common biases in the fossil record Towards common widespread species Lots of biodiversity is globally rare or occupies geographically small ranges Towards physically large species The VAST majority of biodiversity is small to tiny in body size Towards species that died in substrates that lent themselves to long term preservation Towards hard body parts shells and other mineral based structures For example Animals with hard parts are more likely to be preserved than those that only have soft bodies Large fossils are easier to be found stronger so less likely to be destroyed and more likely to be preserved and large creatures tend to be fewer in number than small creatures giving the reverse bias to the fossil record Of the variety of forms in a higher taxon that were present in the remote past only a few have persisted in the long term Over time the composition of the biota increasingly resembles that of the present