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Early Triassic Marine Biotic Recovery



Another new paper: 
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0088987;jsessionid=D51520EFE466DC952C242885BED75637


Scheyer TM, Romano C, Jenks J, Bucher H (2014) Early Triassic Marine Biotic 
Recovery: The Predators' Perspective. PLoS ONE 9(3): e88987. 
doi:10.1371/journal.pone.0088987


Examining the geological past of our planet allows us to study 
periods of severe climatic and biological crises and recoveries, biotic 
and abiotic ecosystem fluctuations, and faunal and floral turnovers 
through time. Furthermore, the recovery dynamics of large predators 
provide a key for evaluation of the pattern and tempo of ecosystem 
recovery because predators are interpreted to react most sensitively to 
environmental turbulences. The end-Permian mass extinction was the most 
severe crisis experienced by life on Earth, and the common paradigm 
persists that the biotic recovery from the extinction event was 
unusually slow and occurred in a step-wise manner, lasting up to eight 
to nine million years well into the early Middle Triassic (Anisian) in 
the oceans, and even longer in the terrestrial realm. Here we survey the global 
distribution and size spectra of Early Triassic and Anisian 
marine predatory vertebrates (fishes, amphibians and reptiles) to 
elucidate the height of trophic pyramids in the aftermath of the 
end-Permian event. The survey of body size was done by compiling maximum 
standard lengths for the bony fishes and some cartilaginous fishes, and total 
size (estimates) for the tetrapods. The distribution and size 
spectra of the latter are difficult to assess because of preservation 
artifacts and are thus mostly discussed qualitatively. The data 
nevertheless demonstrate that no significant size increase of predators 
is observable from the Early Triassic to the Anisian, as would be 
expected from the prolonged and stepwise trophic recovery model. The 
data further indicate that marine ecosystems characterized by multiple 
trophic levels existed from the earliest Early Triassic onwards
guilds occurred less than two million years after the end-Permian extinction 
event, in which a transition from fish/amphibian to 
fish/reptile-dominated higher trophic levels within ecosystems became 
apparent.