Saturnalia tupiniquim (Langer et al. 1999) Carnian, Late Triassic period, ~225 mya, 1.5 m in length, was one of the oldest true dinosaurs yet found. It was a basal prosauropod.

The skull was recently described (Bronzati, Müller and Langer 2019). It had a large orbit, like Pantydraco. More cervicals were present and each one was elongated, creating a much longer neck. The scapula was narrow in the middle. The forelimbs were more robust with a large deltopectoral crest on the humerus. The hind limbs were more robust. The calcaneum did not have such a large tuber.

Plateosaurus engelhardti (von Meyer 1837; Moser 2003; Late Triassic, 210mya; 5-10m in length) is a prosauropod, basal sauropodomorph phytodinosaur. Over 100 skeletons are known. In the LRT Plateosaurus nests in a clade apart from the sauropods and their ancestors. Saturnalia is smaller and older. Aardonyx is larger and later.

Aardonyx celestae (Yates et al. 2010; Early Jurassic) was originally considered a basal sauropodomodph dinosaur. Here it nests with the prosauropod, Saturnalia, a taxon not mentioned originally. Aardonyx is larger, more robust and has shorter feet as in sauropods, making it a sauropod mimic.

Bronzati M, Müller RT, Langer MC 2019. Skull remains of the dinosaur Saturnalia tupiniquim (Late Triassic, Brazil): With comments on the early evolution of sauropodomorph feeding behaviour. PLoS ONE 14(9): e0221387. https://doi.org/ 10.1371/journal.pone.0221387

Langer MC, Abdala F, Richter M, and Benton M. 1999. A sauropodomorph dinosaur from the Upper Triassic (Carnian) of southern Brazil. Comptes Rendus de l'Académie des Sciences, 329: 511-517.

Langer MC 2003. The pelvic and hind limb anatomy of the stem-sauropodomorph Saturnalia tupiniquim (Late Triassic, Brazil). PaleoBios, 23(2): 1-30.

Meyer H von 1837. Mitteilung an Prof. Bronn (Plateosaurus engelhardti [message to Prof. Bronn (Plateosaurus engelhardti)]. Neues Jahrbuch für Geologie und Paläontologie (in German). 1837: 316.

Moser M 2003. Plateosaurus engelhardti Meyer, 1837 (Dinosauria, Sauropodomorpha) aus dem Feuerletten (Mittelkeuper; Obertrias) von Bayern [Plateosaurus engelhardti Meyer, 1837 (Dinosauria, Sauropodomorpha) from the Feuerletten (Mittelkeuper; Obertrias) of Bavaria]. Zitteliana Reihe B: Abhandlungen der Bayerischen Staatssammlung für Paläontologie und Geologie (in German and English). 24: 1–186.

Yates AM, Bonnan MF, Neveling J, Chinsamy A and Blackbeard MG 2010. A new transitional sauropodomorph dinosaur from the Early Jurassic of South Africa and the evolution of sauropod feeding and quadrupedalism. Proceedings of the Royal Society B. 277 (1682): 787–794.

wiki/Saturnalia
wiki/Aardonyx
wiki/Plateosaurus