Crocodilian diversity in space and time: the role of climate in paleoecology and its implication for understanding K/T extinctions
- 1 January 1998
- journal article
- research article
- Published by Cambridge University Press (CUP) in Paleobiology
- Vol. 24 (4) , 470-497
- https://doi.org/10.1017/s009483730002011x
Abstract
The taxonomic diversity of crocodilians (Crocodylia) through the last 100 million years shows a general decline in the number of genera and species to the present day. But this masks a more complex pattern. This is investigated here using a comprehensive database of fossil crocodilians that provides the opportunity to examine spatial and temporal trends, the influence of sampling, and the role of climate in regulating biodiversity.Crown-group crocodilians, comprising the extant families Alligatoridae, Crocodylidae, and Gavialidae, show the following trend: an initial exponential diversification through the Late Cretaceous and Paleocene that is restricted to the Northern Hemisphere until after the K/T boundary; relatively constant diversity from the Paleocene into the middle Eocene that may be an artifact of sampling, which might mask an actual decline in numbers; low diversity during the late Eocene and Oligocene; a second exponential diversification during the Miocene and leveling off in the late Miocene and Pliocene; and a precipitous drop in the Pleistocene and Recent. The coincidence of drops in diversity with global cooling is suggestive of a causal link—during the initial glaciation of Antarctica in the Eocene and Oligocene and the Northern Hemisphere glaciation at the end of the Pliocene. However, matters are complicated in the Northern Hemisphere by the climatic effects of regional uplift.Although the global trend of diversification is unperturbed at the K/T boundary, this is largely due to the exceptionally high rate of origination in the early Paleocene. Nonetheless, the survival of such a demonstrably climate-sensitive group strongly suggests that a climatic explanation for the K/T mass extinctions, especially the demise of the dinosaurs, must be reconsidered.Keywords
This publication has 39 references indexed in Scilit:
- Fossil crocodilians as indicators of Late Cretaceous and Cenozoic climates: implications for using palaeontological data in reconstructing palaeoclimatePalaeogeography, Palaeoclimatology, Palaeoecology, 1998
- Constant extinction, constrained diversification, and uncoordinated stasis in North American mammalsPalaeogeography, Palaeoclimatology, Palaeoecology, 1996
- Species Diversity in Space and TimePublished by Cambridge University Press (CUP) ,1995
- Tertiary climatic changes at middle latitudes of western North AmericaPalaeogeography, Palaeoclimatology, Palaeoecology, 1994
- Middle Eocene through Early Oligocene climate history and paleoceanography in the Southern Ocean: Stable oxygen and carbon isotopes from ODP Sites on Maud Rise and Kerguelen PlateauMarine Geology, 1992
- Who's Holding the Watch?PALAIOS, 1986
- Turtle, crocodilian, and champsosaur diversity changes in the Cenozoic of the north-central region of western United StatesPalaeogeography, Palaeoclimatology, Palaeoecology, 1982
- Primary Productivity of the BiospherePublished by Springer Nature ,1975
- Krokodile als KlimazeugenInternational Journal of Earth Sciences, 1964
- The history of fossil crocodilesProceedings of the Geologists' Association, 1886