Titanosaur sauropod

Article By:

Curry Rogers, Kristi Departments of Biology and Geology, Macalester College, St. Paul, Minnesota.

Last reviewed:2009

DOI:https://doi.org/10.1036/1097-8542.YB090062

Titanosauria was a diverse, globally distributed clade (a taxonomic group containing a common ancestor and its descendants) of herbivorous sauropod dinosaurs. [Sauropoda is a subgroup of the Sauropodomorpha subdivision of Saurichia (one of the two major monophyletic clades of Dinosauria, the other being Ornithischia).] During the Cretaceous Period (144–65 million years ago) when most other sauropod lineages became extinct, titanosaurs flourished and remained an integral part of terrestrial ecosystems. Body fossils from more than 40 valid titanosaur species are known from Late Jurassic to Late Cretaceous sediments and from every continent except Antarctica. The unique, wide-gauge trackways of titanosaurs extend their temporal range back as far as the Mid-Jurassic Period. In spite of their extensive temporal and geographic range, the titanosaur fossil record has been historically patchy, with many species known from only a few isolated bones. The past 10 years have witnessed a surge in professional and public interest in this enigmatic group of sauropods. Important new specimens have been identified that illustrate the cranial and postcranial morphology characteristic of the group, and permit recognition of a suite of locomotor features that depart in important ways from those of other sauropods. The titanosaur sample has increased to encompass the first embryonic titanosaur fossils and eggs, coprolites (fossil feces) that reveal titanosaur diets, and the first associated skulls and skeletons represented by an ontogenetic (developmental) sample. The origin of Titanosauria is well supported by these new data, although its species-level relationships remain poorly resolved. A broad phylogenetic perspective on titanosaurs is on the verge of being developed, which will enable more detailed aspects of their paleobiology, paleobiogeography, and evolutionary history to be investigated.

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