Abstract
Crocodylian snouts in space and time; phylogenetic approaches toward mapping the temporal fates of adaptive radiations
Abstracts with programs - Geological Society of America, Vol.32(7), p.132
Geological Society of America, 2000 annual meeting
2000
Abstract
Specimen-based phylogenetic analyses of fossil and living crocodylians allow comparison of taxonomic, paleogeographic, and temporal distributions of morphological features, such as snout shapes. A few basic specialized snout morphotypes--long and slender, short and blunt, deep, and excessively broad--occur multiple times in distantly-related lineages. Clades with minimum origination dates in the Cretaceous or Early Tertiary are morphologically uniform, but geographically widespread; crocodylian faunas of the early Tertiary tend to be composite, with sympatric taxa being distantly related, and similar-looking taxa on different continents being close relatives. Western Hemisphere crocodylian faunas remained phylogenetically composite throughout the Tertiary. In contrast, Old World crocodylian faunas of the later Tertiary tend to be more endemic, with local adaptive radiations occurring in Africa and Australia containing members of most basic snout shapes. Climate change is usually seen as the primary agent behind crocodylian diversity changes over time. Increased separation between continental land-masses during the later Tertiary may have prevented widespread dispersal of specialized clades, allowing multiple endemic radiations to occur. This suggests that tectonics may be partially responsible for an increase in crocodylian diversity early in the Neogene. A phylogenetic perspective enhances our interpretation of temporal patterns, because the biogeographic details recovered from the calibrated phylogeny are not evident from counts of taxa over time. And re-examination of curated specimens is critical for the recovery of these patterns, as taxonomic philosophies have fluctuated over time, and published classifications may not mirror phylogenetic relationships.
Details
- Title: Subtitle
- Crocodylian snouts in space and time; phylogenetic approaches toward mapping the temporal fates of adaptive radiations
- Creators
- Christopher A Brochu - Field Museum of Natural History
- Resource Type
- Abstract
- Publication Details
- Abstracts with programs - Geological Society of America, Vol.32(7), p.132
- Conference
- Geological Society of America, 2000 annual meeting
- Publisher
- Geological Society of America (GSA)
- ISSN
- 0016-7592
- Alternative title
- Geological Society of America, 2000 annual meeting
- Language
- English
- Date published
- 2000
- Academic Unit
- Earth and Environmental Sciences; University College Courses
- Record Identifier
- 9984240912902771
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