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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)
doi: 10.1111/j.1466-8238.2011.00735.x
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 
disparate LBGs.
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.