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[Paleontology • 2016] The “χ” of the Matter: Testing the Relationship between Paleoenvironments and Three Theropod Clade

Fig 5. Reconstruction of the terrestrial paleoenvironmental setting of the Sao Khua Formation, Northeastern Thailand.
In the center, a generalized spinosaurid feeds on a sauropod. This trophic relationship is hypothesized based on isolated tooth crowns found in association with a sauropod skeleton [Buffetaut & Suteethorn, 1999]. In the background, a small pack of the ornithomimosaur theropod Kinnareemimus. Both sauropods and ornithomimosaurs (as part of the “herbivorous” theropods) were found to be positively associated with terrestrial paleoenvironments by Butler and Barrett (2008)

Illustration: Renata Cunha DOI: 10.1371/journal.pone.0147031

Abstract

The view of spinosaurs as dinosaurs of semi-aquatic habits and strongly associated with marginal and coastal habitats are deeply rooted in both scientific and popular knowledge, but it was never statistically tested. Inspired by a previous analysis of other dinosaur clades and major paleoenvironmental categories, here we present our own statistical evaluation of the association between coastal and terrestrial paleoenvironments and spinosaurids, along with other two theropod taxa: abelisaurids and carcharodontosaurids. We also included a taphonomic perspective and classified the occurrences in categories related to potential biases in order to better address our interpretations. Our main results can be summarized as follows: 1) the taxon with the largest amount of statistical evidence showing it positively associated to coastal paleoenvironments is Spinosauridae; 2) abelisaurids and carcharodontosaurids had more statistical evidence showing them positively associated with terrestrial paleoenvironments; 3) it is likely that spinosaurids also occupied spatially inland areas in a way somehow comparable at least to carcharodontosaurids; 4) abelisaurids may have been more common than the other two taxa in inland habitats.

Fig 4. Schematic illustration of the spatial distribution of Abelisauridae, Carcharodontosauridae, and Spinosauridae throughout coastal and terrestrial paleoenvironments.
Spinosaurids seem to have been natural inhabitants of coastal settings, while terrestrial and more inland habitats were shared by them and both abelisaurids and carcharodontosaurids. Note that the number of body icons (not to scale) does not reflect perfectly the relative abundance of these taxa within each paleoenvironment.

DOI: 10.1371/journal.pone.0147031

Marcos A. F. Sales , Marcel B. Lacerda, Bruno L. D. Horn, Isabel A. P. de Oliveira and Cesar L. Schultz. 2016. The “χ” of the Matter: Testing the Relationship between Paleoenvironments and Three Theropod Clades.
PLoS ONE. DOI: 10.1371/journal.pone.0147031

Buffetaut E and Suteethorn V. 1999. The dinosaur fauna of the Sao Khua Formation of Thailand and the beginning of the Cretaceous radiation of dinosaurs in Asia. Palaeogeogr Palaeoclimatol Palaeoecol. 150: 13–23. doi: 10.1016/s0031-0182(99)00004-8

Butler RJ and Barrett PM. 2008. Palaeoenvironmental controls on the distribution of Cretaceous herbivorous dinosaurs. Naturwissenschaften. 95: 1027–32. doi: 10.1007/s00114-008-0417-5.