The first allokotosaurian from South America and the Gondwanan radiation of non-archosauriform archosauromorphs

Allokotosaurians achieved a nearly cosmopolitan distribution during the Triassic Period, obtaining a high taxonomic diversity and a variety of feeding habits. However, allokotosaurians have not yet been recorded in South America. In the Candelária Sequence of Southern Brazil, the upper Niemeyer Complex (Early Norian) provided a new specimen, CAPPA/UFSM 0415, which represents the first record of Allokotosauria in South America. The specimen is composed of two cervical vertebrae, with a combination of character states supporting its placement within Malerisaurinae. Biostratigraphic correlations with other localities with malerisaurines, especially India, reinforce the proposals of a Late Carnian to Norian age to the Upper portion of the Niemeyer Complex. The internal anatomy of CAPPA/UFSM 0415 reveals a dense apneumatic trabecular matrix without zonations of increased vasculature. The evolution of complex internal vertebral architectures and vascularization from early archosauromorphs, such as allokotosaurians, towards later-derived groups favoured the opportunistic invasion of air sac diverticula in avemetatarsalian clades in the Late Triassic onwards. In addition, the new specimen completes the crocopodan radiation of non-archosauriform archosauromorphs in South America, encompassing the clades Rhynchosauria, Tanysauria and, with this contribution, Allokotosauria. Finally, the discovery of CAPPA/UFSM 0415 increases the distribution of the azendohsaurids throughout Gondwana.