Paper No. 15
Presentation Time: 5:15 PM
A 600 MILLION YEAR RECORD OF ECOLOGICAL DIVERSIFICATION
HENDY, Austin J.W.1, ABERHAN, Martin
2, ALROY, John
3, CLAPHAM, Matthew E.
4, KIESSLING, Wolfgang
2, LAFLAMME, Marc
5 and LIN, Jih-Pai
6, (1)Center for Tropical Palaeontology and Archaeology, Smithsonian Tropical Research Institute, 601 East Street, Balboa, Ancon, 0843-03092, Panama, (2)Institut für Paläontologie, Museum für Naturkunde, Invalidenstr. 43, Berlin, 10115, Germany, (3)Department of Biological Sciences, Macquarie University, Room E8A 320, Sydney, 2109, Australia, (4)Department of Earth and Planetary Sciences, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, (5)Department of Geology and Geophysics, Yale University, PO Box 208109, New Haven, CT 06511, (6)Geology and Geophysics, Yale University, New Haven, CT 06520, hendyaj@si.edu
The ecological diversity of marine landscapes may be defined as the number of unique ways in which organisms interact with the environment and with one another (feeding, locomotion, and tiering), herein referred to as ecospace. Previous studies have shown that realized ecospace has increased markedly since the earliest known marine animal ecosystems. These studies are, however, limited to snapshots through evolutionary history. The Paleobiology Database (www.paleodb.org) provides a unique resource for analyzing a continuous time-series of ecospace occupancy from the fossil record. The present analysis incorporates nearly half a million fossil occurrences, and represents close to 20,000 genera of marine animals.
We show that globally sampled ecospace indeed rose sharply between the Ediacaran and the Cambrian, although this is partly biased by the exceptional preservation of non-skeletonized organisms in Cambrian konservat-lagerstätten. Sampled ecospace reaches a plateau during the Late Ordovician, only increasing further during the mid-Jurassic. Even though the number of ecospace units occupied remained relatively stable following the early Paleozoic increase, ecological composition shifted dramatically. Most notable is a shift from Paleozoic epifaunal to post-Paleozoic infaunal life-habits, and an increase in carnivory through the Phanerozoic. These data can also be used to test the severity of extinction events in the context of ecological complexity. The end-Permian is the only major extinction event to result in a long-term shift in the occupation of ecospace, with epifaunal stationary suspension-feeders declining and nektonic actively mobile carnivores increasing in their frequency of occurrence. Analysis of community-scale occupation of ecospace (the typical number of modes of life observed in individual assemblages) reveals a slightly different pattern; remaining low throughout the Paleozoic before rising sharply in the early Mesozoic. These results point to the need to investigate evolutionary processes and the consequences of abiotic perturbations with new data, analytical approaches, and at a range of spatial scales
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