Euknemesaurus (lat.: Eucnemesaurus) is the basal (original) genus of Sauropodomorphs (Sauropodomorpha), which lived on Earth in the Upper Triassic period. It was first scientifically described in 1920 by paleontologist van Hoepen from fragmentary fossils found in South Africa’s Elliot Formation.: Elliot-Formation), which refers to the Upper Triassic.
For a long time, euknemesaurus was considered an invalid genus: this name was declared either a synonym for euskelosaurus (Euskelosaurus) or a dubious name (Nomen dubium). However, a 2007 study by Adam Yates suggests that Euknemesaurus is identical to Aliwalia, which is traditionally considered a large basal theropod and often placed in the Herrerasauridae family. Yeats proved that euknemesaurus is actually a basal genus of sauropodomorphs related to sauropods.
Since “Eucnemesaurus” is the first described name, it should be considered the valid name of the genus, and the later synonym “Alivalia” is not valid. This genus is represented by a single species Eucnemesaurus fortis.
Generic name “Eucnemesaurus” (gr.: eu “good, strong”, kneme “shin”, sauros “lizard”) indicates that we are talking about a lizard with a powerful tibia.
Yeats Cladistic Analysis (2007).) showed that Euknemesaurus was a close relative of Riojasaurus (Riojasaurus). Therefore, the scientist combined these two genera into a new group called Riojasauridae (Riojasauridae). This group was more closely related to the sauropods than to the Plateosaurids (Plateosauridae), but was more primitive than the Massospondylid family (Massospondylidae).
Like the closely related Riochasaurus, Euknemesaurus was a large, powerfully built sauropodomorph. According to Adam Yates, it is distinguished from other genera by one special feature of the dorsal vertebrae and two features of the morphology of the trochanter (femoral trochanter).
The holotype material, described by van Hopen as a eucnemesaurus (specimen number: TM 119), includes fragments of dorsal vertebrae, 4 caudal vertebrae, fragments of a pubic bone, upper end of a femur, and a tibia. These remains were discovered on the territory of a farm located near the town of Slabberts in the South African province of the Free State.
At the same time, the material of the holotype belonging to the species Aliwalia rex consists of the ends of the left femur. And it was discovered in the city of Aliwal North (Aliwal North) in the Eastern Cape of South Africa.
Another find, an incomplete skeleton of Aliwalia, includes one dorsal and one caudal vertebra, a crow bone (coracoid), fragments of both shoulder blades, as well as 1 fragment of a femur and 2 fragments of ribs. This skeleton was excavated in Rosendal, Free State.