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founder of modern geology
Who created the principle of faunal succession and published the first geological map of England?
principle of faunal succession
- Rocks were characterized by unique sets of fossil taxa: faunas
- Faunas represent the diversity of living things at the time sediment was laid down.
- The occurrence of many fossils was independent of the lithology of the rock.
By noting the fossils present in rock, it became possible to
- correlate rock units of varying lithologies across vast distances
- establish time horizons in lithologically uniform or diachronous rock units
Who came up with the idea of uniformitarianism?
What is uniformitarianism?
Natural processes operating today are the same as those which operated in the past. (i.e. Laws of nature are constant.)
- fossils useful in biostratigraphy; used to define geologic periods of time
- common, geographically widespread, easily preservable, diagnosable, found in multiple environments (when dead), short species duration
- ex. ammonites, shelled cephalopods that evolved quickly (lasted only a few mil years but were distributed worldwide)
- fossils of organisms that endured for long periods of geologic time but were linked to a specific environment
- ex. Lingula, a brachiopod living only in lagoonal mudflats that has changed very little in the last 500 mil years
groups of formations characterized by distinct faunal assemblages. e.g. Carnian stage of the late Triassic series
group of stages. e.g. late Triassic series
The Phanerozoic marine family biodiversity curve is characterized by
- periods of rapid increase and decrease: radiation and extinctions
- diversity plateau
- overall increase in diversity
Evolutionary faunas refer to
patterns of origination, dominance, and extinction
evolutionary faunas in the Phanerozoic eon
- Cambrian: trilobites and archaeocyaths
- Paleozoic: brachiopods and echinoderms
- Modern: decapods and bivalves
What happened during the Ordovician (Paleozoic era) radiation?
- rapid diversification (tripled) including reef builders
- rise to dominance of Paleozoic faun
- aincrease in ecological complexity
What ecological changes occurred during the Ordovician period?
- organisms living in close association; tightly packed communities e.g. shell beds
- ecospace utilization: "tiering" Plants/organisms went from being only on the ocean floor to also being under the sediment
greatest concentration of nutrients typically on/at ocean floor, but less competition in the water column
normal rate at which individual species go extinct
period with numerous species extinctions which are significantly greater normal "background" rates
The first mass extinction of the Paleozoic era was
the Ordovician extinction: 2nd biggest (~60% genera)
The Ordovician extinction was caused by
glaciations: lowered sea level, destroyed shallow marine habitats
What organisms were affected by the Ordovician extinction?
stromatoporoids, rugose, and tabulate corals
The 2nd mass extinction of the Paleozoic era was
the late Devonian extinction: depressed origination rates, huge affects on reefs
possible causes of the late Devonian extinction
glaciation: sea level and climatic changes, asteroid impacts, global marine anoxia, volcanism, reduced CO2 in plants
What organisms were affected by the late Devonian extinction?
(severely affected) brachiopods, trilobites, ammonoids, placoderms
What happened to reef communities during the late Devonian extinction?
- Geographic extent shrank severely.
- Tabulate corals lost 70-80%; did not recover.
- Stromatoporoids became extinct.
diversity recovery of the late Devonian extinction
Most organisms seem to recover. (Trilobites die off.)
There was a severe ecological effect after the __ extinction
There was a transition from __ dominated beds to __ dominated after the late Devonian extinction.
The Ordovician and Devonian extinctions had similar losses in __
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