Matheus Fernandes / UFRJArtistic rendering of two Itaguyra occulta (in the foreground), which lived 237 million years agoMatheus Fernandes / UFRJ
Among a set of fossils stored at the Federal University of Rio Grande do Sul (UFRGS) for several decades was Itaguyra occulta, which appears to represent a new silesaurid species. This group was long considered a precursor to dinosaurs, but is now increasingly seen as the oldest branch of one of the main dinosaur lineages: the ornithischians (see Pesquisa FAPESP issue n° 279). What makes this discovery notable is that the animal lived 237 million years ago, a period from which no silesaurid fossils have previously been found in southern Brazil. The region is considered the earliest cradle of dinosaurs, which emerged around 230 million years ago. The fossil was found alongside that of a cynodont, an early ancestor of the mammals. Paleontologist Voltaire Paes Neto of the National Museum at the Federal University of Rio de Janeiro (UFRJ) and his Argentine colleague Agustín Martinelli, from the Argentine Museum of Natural Sciences, recognized characteristics of the silesaurids. The discovery reinforces that this group of animals was remarkably persistent in the face of changes that caused profound alterations in the fauna, remaining in the region that is now Rio Grande do Sul for around 11 million years (Scientific Reports, May 30).
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