Coloradisaurus brevis was originally namedColoradia brevis byJosé Bonaparte in 1979,[4][5] but that genus name was preoccupied by the pine mothColoradia,[6] so it needed areplacement name. In 1983, David Lambert used the nameColoradisaurus for the genus, but did not indicate it was a replacement or diagnose it.[7] Lambert had gotten the name from Bonaparte in a personal communication and mistakenly thought that Bonaparte had already published it.[3]Peter Galton was the next to use the nameColoradisaurus in 1990, which he credited to Lambert, when he gave the taxon a diagnosis in his review of prosauropods inThe Dinosauria.[2][3]Authorship ofColoradisaurus has traditionally been attributed to Lambert, but Greenfield, Bivens and Fonseca (2020) judged Lambert's use of the name to be anomen nudum. They concluded that authorship should be attributed to Galton, who was the first to use the nameColoradisaurus in a way that met the requirements of theICZN.[3]
The holotype ofColoradisaurus (PVL 3967) is a mostly complete skull found associated with an undescribed partial skeleton.[5] While the right side of the skull is well-preserved with almost all bones intact, the left side is distorted and missing more bones.[8] The holotype individual has been estimated to have been 3 m (10 ft) long with a mass of 70 kg (150 lb).[9] A referred specimen (PVL 5904) is a partial skeleton including most of the dorsal vertebrae and parts of the pectoral and pelvic girdles and limbs.[10] LikeLufengosaurus, it have the angle between the pterygoid and quadratojugal rami nearly 90°. There is also a possibility that the postorbital bones ofColoradisaurus andSarahsaurus are similar, but due to the deformation of the skull this is difficult to say.[11]
Coloradisaurus was classified as aplateosaurid in the original description by Bonaparte,[5] but this pre-dated the use ofphylogenetic analyses in paleontology. He later became opposed tocladistics[12] and continued to considerColoradisaurus a plateosaurid without testing its phylogenetic position.[13] The analyses of Galton (1990), Galton & Upchurch (2004), and Upchurch et al. (2007) found it to be a plateosaurid, supporting Bonaparte's placement.[2][14][15] However, the analyses of Benton et al. (2000) and Yates (2003) recovered it in apolytomy with other basal sauropodomorphs or as amassospondylid, respectively.[16][17] Subsequent analyses such as Yates et al. (2010), Apaldetti et al. (2013; 2014), Wang et al. (2017), and Müller (2020) have reached the consensus thatColoradisaurus is a massospondylid most closely related toLufengosaurus andGlacialisaurus.[8][10][18][19][11][20] These three taxa share foursynapomorphies found in the metatarsals and femur.[10]
Below is a simplified cladogram after Galton & Upchurch (2004), reflecting its early placement as a plateosaurid.[14]
^abcGalton, P.M. (1990). "Basal Sauropodomorpha - Prosauropoda". In Weishampel, D.B.; Dodson, P.; Osmólska, H. (eds.).The Dinosauria. Berkeley, CA: University of California Press. pp. 320–344.ISBN0-520-06726-6.
^abcdeGreenfield, T.; Bivens, G.; Fonseca, A. (2020). "The correct authorship ofColoradisaurus (Dinosauria, Sauropodomorpha): Galton, 1990, not Lambert, 1983".Bulletin of Zoological Nomenclature.77 (1):153–155.doi:10.21805/bzn.v77.a050.S2CID229723564.
^abMones, A. (2025). "The correct year of publication ofColoradia brevis Bonaparte (currentlyColoradisaurus brevis; Dinosauria, Prosauropoda, Massospondylidae) is 1979, not 1978".Bulletin of Zoological Nomenclature.82 (1):171–174.doi:10.21805/bzn.v82.a029.
^abcApaldetti, C.; Martinez, R.N.; Pol, D.; Souter, T. (2014). "Redescription of the Skull ofColoradisaurus brevis (Dinosauria, Sauropodomorpha) from the Late Triassic Los Colorados Formation of the Ischigualasto-Villa Union Basin, northwestern Argentina".Journal of Vertebrate Paleontology.34 (5):1113–1132.Bibcode:2014JVPal..34.1113A.doi:10.1080/02724634.2014.859147.hdl:11336/36518.S2CID86158311.
^abGalton, P.M.; Upchurch, P. (2004). "Prosauropoda". In Weishampel, D.B.; Dodson, P.; Osmólska, H. (eds.).The Dinosauria (2nd ed.). Berkeley, CA: University of California Press. pp. 232–258.ISBN0-520-24209-2.
^Benton, M.J.; Juul, L.; Storrs, G.W.; Galton, P.M. (2000). "Anatomy and systematics of the prosauropod dinosaurThecodontosaurus antiquus from the upper Triassic of southwest England".Journal of Vertebrate Paleontology.20 (1):77–108.doi:10.1671/0272-4634(2000)020[0077:AASOTP]2.0.CO;2.
