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Dinosaur paleodiversity peaked in temperate zones
From: Ben Creisler
A new online paper:
Mannion, P. D., Benson, R. B. J., Upchurch, P., Butler, R. J., Carrano, M. T.
and Barrett, P. M. (2011)
A temperate palaeodiversity peak in Mesozoic dinosaurs and evidence for Late
Cretaceous geographical partitioning.
Global Ecology and Biogeography (advance online publication)
Aim Modern biodiversity peaks in the tropics and declines poleward, a pattern
that is potentially driven by climate. Although this latitudinal biodiversity
gradient (LBG) also characterizes the marine invertebrate fossil record,
distributions of ancient terrestrial faunas are poorly understood. This study
utilizes data on the dinosaur fossil record to examine spatial patterns in
terrestrial biodiversity throughout the Mesozoic.
Location We compiled data on fossil occurrences across the globe.
Methods We compiled a comprehensive dataset of Mesozoic dinosaur genera (738),
including birds. Following the utilization of sampling standardization
techniques to mediate for the uneven sampling of the fossil record, we
constructed latitudinal patterns of biodiversity from this dataset.
Results The dominant group of Mesozoic terrestrial vertebrates did not conform
to the modern LBG. Instead, dinosaur diversity was highest at temperate
palaeolatitudes throughout the 160 million year span of dinosaurian
evolutionary history. Latitudinal diversity correlates strongly with the
distribution of land area. Late Cretaceous sauropods and ornithischians exhibit
Main conclusions The continuity of the palaeotemperate peak in dinosaur
diversity indicates a diminished role for climate on the Mesozoic LBG; instead,
dinosaur diversity may have been driven by the amount of land area among
latitudinal belts. There is no evidence that the tropics acted as a cradle for
dinosaur diversity. Geographical partitioning among major clades of herbivorous
e Cretaceous may result from the advanced stages of continental fragmentation
and/or differing responses to increasing latitudinal climatic zonation. Our
results suggest that the modern-day LBG on land was only established 30 million
years ago, following a significant post-Eocene recalibration, potentially
related to increased seasonality.