The Triassic deposits of South America are key to understand the early radiation of Dinosauromorpha. Though the fossil record of the group is relatively abundant in Carnian- and Norian-aged strata from Argentina and Brazil, Middle Triassic dinosauromorphs are scarce, at least in the Brazilian record. In this contribution, we describe a set of fossils collected from a site biostratigraphically correlated to the Assemblage Zone, which is regarded as Ladinian in age. Within the sample, we identified a single partial ilium with anatomical features consistent with Silesauridae. As a result, we propose a new taxon, gen. et sp. nov. as the first silesaurid from the Brazilian Middle Triassic. Biostratigraphic comparisons suggest the Assemblage Zone to be older than the Argentinean - AZ, rendering the new specimen also the oldest South American silesaurid. This contribution adds to recent works that suggest biostratigraphical similarity between the Brazilian AZ and the African Lifua Member and Ntawere Formation, from where the oldest dinosauromorph records are registered.

中文翻译：

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最古老的南美西里龙科：中三叠世（Pinheiros-Chiniquá 序列，恐龙龙组合带）的新遗骸扩大了巴西南部西里龙科化石记录的时间范围


南美洲的三叠纪沉积物是了解恐龙形目早期辐射的关键。尽管该类群的化石记录在阿根廷和巴西的卡尼期和诺利安期地层中相对丰富，但中三叠世恐龙形态却很少，至少在巴西记录中是这样。在这篇文章中，我们描述了从生物地层学上与组合带相关的地点收集的一组化石，该组合带的年龄被认为是拉丁阶的。在样本中，我们发现了一个具有与西里龙科一致的解剖特征的部分髂骨。因此，我们提出了一个新的分类单元，gen。等十一月作为巴西中三叠纪的第一个西里龙科动物。生物地层学比较表明，该组合带比阿根廷-AZ更古老，使得新标本也是南美洲最古老的西里龙科。这项贡献补充了最近的工作，这些工作表明巴西AZ和非洲Lifua段和Ntawere组之间的生物地层相似性，最古老的恐龙形态记录就是从那里登记的。