Thecodontosaurus antiquus (Morris 1843, est 2m in length, Rhaetian, Late Triassic, 202mya) is a small bipedal sauropodomorph and among the first dinosaurs discovered. Here it nests basal to Massospondylus. Note the slender fingers.

Massospondylus kaalae (Riley and Stutchbury 1836, Morris 1843, Reisz et al. 2005) was a short-snouted basal sauropodomorph closely related to Efraasia and Saturnalia. Like Heterodontosaurus and Daemonosaurus, Massospondylus had a short round snout and long fangs. Another species, Massospondylus carinatus, had a longer skull with a relatively shorter dentary. This is the largest dinosaur at reptileevolution.com.

The embryo Massospondylus (below) includes a taller antorbital fenestra, a premaxilla lacking a posterior narial process, a straight (not descending) jaw joint, a smaller coronoid process, a lack of teeth, relatively shorter neck, larger fore limbs, a shorter ventral pelvis, distally broader chevrons and smaller feet. Most importantly, it is quadrupedal, like later sauropods.

Barrett PM 2009. A new basal sauropodomorph dinosaur from the upper Elliot formation (Lower Jurassic) of South Africa. Journal of Vertebrate Paleontology 29(4):1032-1045.

Morris J 1843. A Catalogue of British Fossils. British Museum, London, 222 pp.

Reisz RR, Scott D; Sues H-D, Evans DC and Raath MA 2005. Embryos of an Early Jurassic prosauropod dinosaur and their evolutionary significance. Science. 309(5735): 761–764.

Reisz RR, Evans DC, Roberts EM, Sues H-D and Yates AM 2012. Oldest known dinosaurian nesting site and reproductive biology of the Early Jurassic sauropodomorph Massospondylus PDF. Proceedings of the National Academy of Sciences of the United States of America. 109(7): 2428–2433.

Riley H and Stutchbury S 1836. A description of various fossil remains of three distinct saurian animals discovered in the autumn of 1834, in the Magnesian Conglomerate on Durdham Down, near Bristol. Proceedings of the Geological Society of London 2:397-399.

Yates AM and Vasconcelo CC 2005. Furcula-like clavicles in the prosauropod dinosaur Massospondylus. Journal of Vertebrate Paleontology. 25 (2): 466–468. doi:10.1671/0272-4634(2005)025[0466:FCITPD]2.0.CO;2

wiki/Massospondylus
wiki/Thecodontosaurus