Coloradisaurus

Coloradisaurus (meaning "Los Colorados lizard") is a genus of massospondylid sauropodomorph dinosaur. It lived during the Late Triassic period (Norian stage) in what is now La Rioja Province, Argentina. It is known from two specimens collected from the Los Colorados Formation of the Ischigualasto-Villa Unión Basin.
Taxonomy.
"Coloradisaurus" was originally named "Coloradia brevis" by José Bonaparte in 1978, but that genus name was preoccupied by the pine moth "Coloradia". David Lambert unintentionally proposed "Coloradisaurus" as a replacement name in 1983. Lambert had gotten the name from Bonaparte in a personal communication and mistakenly thought that Bonaparte had already published it. Since it was not stated to be a new name, and it did not have a diagnosis or type species, it was a "nomen nudum". In 1990, Peter Galton provided both a diagnosis and a type species for "Coloradisaurus" while still crediting the name to Lambert. Although similarly unintentional, Galton's description meets the requirements of the ICZN and the authorship of "Coloradisaurus" should be attributed to him.
Description.
The holotype of "Coloradisaurus" (PVL 3967) is a mostly complete skull found associated with an undescribed partial skeleton. While the right side of the skull is well-preserved with almost all bones intact, the left side is distorted and missing more bones. The holotype individual has been estimated to have been 3 m (10 ft) long with a mass of 70 kg (150 lb). A referred specimen (PVL 5904) is a partial skeleton including the most of the dorsal vertebrae and parts of the pectoral and pelvic girdles and limbs. All of this material was discovered in 1971 at the La Esquina locality in the upper section of the Los Colorados Formation near Pagancillo, La Rioja Province, Argentina. The top of the Los Colorados Formation has been dated to 213 Ma, which would place "Coloradisaurus" in the Norian stage of the Late Triassic.
Phylogeny.
"Coloradisaurus" was classified as a plateosaurid in the original description by Bonaparte, but this pre-dated the use of phylogenetic analyses in paleontology. He later became opposed to cladistics and continued to consider "Coloradisaurus" a plateosaurid without testing its phylogenetic position. The analyses of Galton (1990), Galton & Upchurch (2004), and Upchurch "et al." (2007) found it to be a plateosaurid, supporting Bonaparte's placement. However, the analyses of Benton "et al." (2000) and Yates (2003) recovered it in a polytomy with other basal sauropodomorphs or as a massospondylid, respectively. Subsequent analyses such as Yates "et al." (2010), Apaldetti "et al." (2013; 2014), Wang "et al." (2017), and Müller (2020) have reached the consensus that "Coloradisaurus" is a massospondylid most closely related to "Lufengosaurus" and "Glacialisaurus". These three taxa share four synapomorphies found in the metatarsals and femur.
Below is a simplified cladogram after Galton & Upchurch (2004), reflecting its early placement as a plateosaurid.
Below is a simplified cladogram after Müller (2020), showing its current position as a massospondylid.