Non-sauropodiform plateosaurians: milestones through the "prosauropod" bauplan

Abstract

The early evolution of Sauropodomorpha is well recorded in Carnian beds of Argentina and Brazil. During the Norian and Rhaetian, sauropodomorphs notably diversified both taxonomically and ecologically, became abundant and ultimately dominated terrestrial ecosystems, adding to the information retrieved from the records from Europe, India, and Southern Africa. Despite the fact that the last decade witnessed an increase in taxonomic abundance of Carnian sauropodomorphs, their morphological disparity is low, characterized by small, gracile, and bipedal forms, with predatory/omnivorous feeding habits. By the Early Jurassic, this group had achieved their broadest geographical distribution and morphological disparity, ranging from small to medium-sized facultative bipedal basal sauropodomorphs to giant quadrupedal sauropods. The major changes in body plan after Carnian forms include the acquisition of features related to herbivory, large body size, and quadrupedality. This chapter is focused on the post-Carnian radiation of sauropodomorphs, for which the South American record accounts for about 25% of the world record. It has provided key information in understanding certain stages of this evolutionary radiation and has therefore highlighted the understanding of the evolution of this group.