Triassic beds from Argentina and Brazil provide the most relevant fossil record of early dinosauriforms in terms of numerical abundance and taxonomic diversity. This record currently represents the best source to understand the origin and early evolutionary radiation of dinosaurs. In the present paper we offer an updated review focused on the available evidence of Carnian dinosaurs from this continent, but we also discuss the record of Triassic dinosaur precursors and the evolution of Triassic dinosaurs in other continents. It is clear that, aside the agreed taxonomic composition of some particular dinosaurian subclades (e.g., Herrerasauridae, Neotheropoda), there is no consensus about early dinosaur phylogeny, and our paper is not the exception. Recent years witnessed the discovery of several new early dinosaurian taxa, as well as reviews of the taxonomic allocation of several renowned forms such as Lagerpeton, Lewisuchus, Pisanosaurus, and Eorpator. New analyses demonstrate that evidence supporting the taxonomic referrals of pre-Norian dinosaurs to Theropoda, Sauropodomorpha and Ornithischia are tenuous, at best. Here we present new anatomical observations and comparisons for each of these South American early dinosauriforms with the aim to test previous phylogenetic interpretations. Evidence from South America allows reviewing the phylogenetic relationships of taxa from other continents, including Tawa, Chindesaurus, and Daemonosaurus, which are here suggested to nest within Herrerasauria. Evidence at hand indicates that herrerasaurs were a successful clade of archaic predatory saurischians that inhabited both South and North America, and probably also India and Europe.

从数量丰度和分类学多样性的角度来看，来自阿根廷和巴西的三叠纪河床提供了最相关的早期恐龙龙化石记录。该记录目前代表了解恐龙的起源和早期进化辐射的最佳来源。在本文中，我们提供了一个更新的综述，重点是来自该大陆的Carnian恐龙的现有证据，但是我们还讨论了三叠纪恐龙的前体记录以及三叠纪恐龙在其他大陆的演化。显然，除了某些特定的恐龙亚群落（例如，Herrerasauridae，Neotheropoda）的公认的生物分类组成外，关于早期恐龙的系统发育尚无共识，我们的论文也不例外。近年来见证了几种新的早期恐龙类群的发现，Lagerpeton，Lewischuus，Pisanosaurus和Eorpator。新的分析表明，支持诺里诺前恐龙分类学推荐到兽脚亚目，兽脚目和虎眼目动物的分类学的证据充其量是微不足道的。在这里，我们介绍了这些南美早期恐龙的每一个的新的解剖学观察结果和比较结果，目的是测试以前的系统发育学解释。来自南美洲的证据可以回顾来自其他大洲（包括塔瓦，钦都龙和Daemonosaurus）的类群的系统发育关系，建议将其嵌套在Herrerasauria中。现有的证据表明，Herrerasaurs是成功地生活在南美和北美以及印度和欧洲的古老掠夺性蜥蜴人的成功分支。