![]() Linear regressions were also employed to estimate the mandible length of Saturnalia, based on the preserved dentaries of MCP-3845-PV. ![]() Our estimates employed a value 15% greater than the preserved length (length as preserved = 29 mm) of the frontal, in order to account for uncertainties regarding the completeness of the anterior margin of the bone (see description below). Skull size was inferred with the aid of linear regressions, based on measurements of other taxa known from more complete specimens (see details in the Results section below). The cranial length of Saturnalia was here estimated based on the length of the right frontal of MCP-3845-PV, which is more complete than the left element. Based on this new information, alongside recent fossil findings and a new principal co-ordinates analysis, we provide new insights on the early evolution of the sauropodomorph feeding behaviour. Herein, we describe all the available skull bones of Saturnalia, except for the braincase, described elsewhere (see ). Later, in 2016, during further preparation of MCP-3845-PV, additional cranial bones were discovered underneath the pelvic girdle of the specimen, including left quadrate, prefrontal, and lacrimal, as well as partial left maxilla and right dentary. In 2014, a Computed Tomography procedure revealed that the parietals and laterosphenoids were preserved inside the matrix of the same block containing the braincase elements. ) incorporated information collected first-hand from those partially exposed elements in their data matrices. In the absence of detailed descriptions, some phylogenetic analyses (e.g. For more than twenty years, the only cranial elements available for Saturnalia (from one of its paratypes) were the frontals, the left squamosal and postorbital, and the braincase, which were preserved exposed on the rock surface of the same block, along with isolated right lacrimal and left dentary. These skeletons were assigned to a new species of sauropodomorph dinosaur, Saturnalia tupiniquim, which was at the time the oldest known member of the group. In early 1998, three skeletons were unearthed during two fieldwork campaigns in the locality commonly known as Cerro da Alemoa or Waldsanga (53☄5’ W 29☄0’ S), located in the outskirts of Santa Maria, south Brazil, in the red mudstones of the Santa Maria Formation. 231 Ma) formations of Brazil and Argentina, respectively. The first steps of sauropodomorph evolution are mainly known based on the fossil record of two South American Carnian deposits, the Santa Maria (c. A second shift, between Late Triassic and Early Jurassic taxa, is congruent with a floral turnover hypothesis across the Triassic-Jurassic boundary. One of these shifts is observed between non-plateosaurian and plateosaurian sauropodomorphs, suggesting that, despite also having an omnivorous diet, the feeding behaviour of some early Carnian sauropodomorphs, such as Saturnalia, was markedly different from that of later Triassic taxa. A principal co-ordinates analysis of the sauropodomorph jaw feeding apparatus shows marked shifts in morphospace occupation in different stages of the first 30 million years of their evolutionary history. Skull reduction in Saturnalia could be related to an increased efficiency for predatory feeding behaviour, allowing fast movements of the head in order to secure small and elusive prey, a hypothesis also supported by data from its tooth and brain morphology. ![]() two thirds of the femoral length) in this taxon, as typical of later sauropodomorphs. The newly described elements allowed estimating the cranial length of Saturnalia and provide additional support for the presence of a reduced skull (i.e. ![]() Here, we describe the skull bones of one of its paratypes (only in the type-series to possess such remains) based on CT Scan data. The osteology of Saturnalia has been described in a series of papers, but its cranial anatomy remains mostly unknown. Due to its phylogenetic position and age, it is important for studies focusing on the early evolution of both dinosaurs and sauropodomorphs. Saturnalia tupiniquim is a sauropodomorph dinosaur from the Late Triassic (Carnian–c.
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