The specimens were at first assigned to three already existing genera and so became divided among three separate species: Teratosaurus minor, Sellosaurus fraasi and Paleosaurus diagnosticus.

Material now known under Efraasia first came to light after Albert Burrer, Hofsteinmetzmeister ("Court master stonemason") at Maulbronn, in 1902 began to exploit the Weiße Steinbruch, a quarry near Pfaffenhofen in Württemberg.

To reach the layer of hard white sandstone Burrer wanted to use for his building projects a 6 metres (20 ft) thick overburden of softer marl had to be removed.

A specimen of a basal sauropodomorph, SMNS 11838, was first described by Friedrich von Huene in 1907–1908 and named as a new species of Teratosaurus: T. minor.

The specific name could not be determined as simply, as both Teratosaurus minor and Sellosaurus fraasi had first appeared in von Huene's 1908 book.

[8] Yates did not take into account two other species based by von Huene on very fragmentary German basal sauropodomorph material, Teratosaurus trossingensis and Thecodontosaurus hermannianus, though Galton had considered them junior synonyms of Efraasia diagnostica in 1990.

[10] Apart from the specimens mentioned above, mostly consisting of rather complete skeletons preserved in large slabs, though not fully prepared from the rock matrix, several other fossils have been found.

[11] Some researchers however, contend that the lower arm did not allow pronation, a rotation of the radius around the ulna, so that the hand could not be directed downward, making the animal an obligate biped.

Yates identifies two unique derived traits (autapomorphies): the presence of a raised crescent-like ridge on the upper part of the inner side of the pubis shaft; and the presence of a vaulted bony web between two lower extensions of a braincase bone, the processus basipterygoidei, with a raised central bony platform on top of the vault.

Von Huene continued interpreting these forms as predatory dinosaurs, in 1932 assigning them to a separate family Palaeosauridae as part of the Carnosauria.

Modern phylogenetic analysis has indicated that Efraasia is a basal sauropodomorph, somewhat more derived than Thecodontosaurus, but less than either the Prosauropoda (including Plateosaurus) or the Sauropoda.