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Stenopterygius (Ichthyosauria) trophic niche ontogeny and palaeoecology



Ben Creisler
bcreisler@gmail.com


A new paper:

Daniel G. Dick, Günter Schweigert and Erin E. Maxwell (2016)
Trophic niche ontogeny and palaeoecology of early Toarcian
Stenopterygius (Reptilia: Ichthyosauria).
Palaeontology (advance online publication)
DOI: 10.1111/pala.12232
http: // onlinelibrary.wiley.com/doi/10.1111/pala.12232/abstract

Data for this study are available in the Dryad Digital Repository:

http: // dx.doi.org/10.5061/dryad.0cn8b


Reconstructing ecological niche shifts during ontogeny in extinct
animals with no living analogues is difficult without exceptional
fossil collections. Here we demonstrate how a previously identified
ontogenetic shift in the size and shape of the dentition in the early
Toarcian ichthyosaur Stenopterygius quadriscissus accurately predicts
a particular dietary shift. The smallest S. quadriscissus fed on
small, burst-swimming fishes, with a steady shift towards faster
moving fish and cephalopods with increasing body size. Larger adult
specimens appear to have been completely reliant on cephalopods, with
fish completely absent from gut contents shortly after onset of sexual
maturity. This is consistent with a previously proposed ontogenetic
niche shift based on tooth shape and body size, corroborating the idea
that dental ontogeny may be a useful predictor of dietary shifts in
marine reptiles. Applying the theoretical framework used here to other
extinct species will improve the resolution of palaeoecological
reconstructions, where appropriate sample sizes exist.