Pronunciation: STOHK-so-SOR-us
Meaning: Stokes' lizard
Author/s: Madsen (1974)
Synonyms: Iliosuchus clevelandi (Galton, 1976)
First Discovery: Utah, USA
Discovery Chart Position: #242
Stokesosaurus clevelandi
Stokesosaurus is one of the oldest confirmed tyrannosauroids. However, the word "confirmed" implies certainty, and there's nothing certain about Stokesosaurus.
James Henry Madsen named Stokesosaurus on the strength of an ilium (hip bone) that he and William Lee Stokes plucked from Utah's Allosaurus-dominated Cleveland Lloyd quarry. It was also assigned an upper jawbone (UUVP 2999) from the same area that turned out to be the property of Tanycolagreus. Then it was shunted to England's ancient tetanuran Iliosuchus as a second species — Iliosuchus clevelandi — in 1976 by Galton, who flip-flopped his own opinion four years later. Some hip bones and tail vertebrae made their way here in 1991, followed by a partial braincase in 1998. Another ilium from South Dakota arrived in 2000, but that has since been lost and may actually belong to the Portuguese tyrant's grandmother: Aviatyrannis.
Stokesosaurus and Tanycolagreus are about the same size, and the pair may be synonymous. But that's tough to prove when the former is anchored by an ilium that wasn't attached to any other bones while the latter is known from other bones that aren't attached to an ilium. Furthermore, Rauhut named Aviatyrannis in 2003 for an ilium from a Portuguese coal mine that he had previously assigned to Stokesosaurus, with some experts unconvinced by its separation. The irony of the tyrant's grandmother being based on a hip replacement is not lost on us.
If the previously mentioned trio represent the same critter, Tanycolagreus will be first for the chop as it was named last, followed by Aviatyrannis regardless of her actual age. In biological nomenclature, the science of naming organisms, it's the first coined name that counts (unless you're Tyrannosaurus or Allosaurus), which would make Stokesosaurus the only valid name for all three.
James Henry Madsen named Stokesosaurus on the strength of an ilium (hip bone) that he and William Lee Stokes plucked from Utah's Allosaurus-dominated Cleveland Lloyd quarry. It was also assigned an upper jawbone (UUVP 2999) from the same area that turned out to be the property of Tanycolagreus. Then it was shunted to England's ancient tetanuran Iliosuchus as a second species — Iliosuchus clevelandi — in 1976 by Galton, who flip-flopped his own opinion four years later. Some hip bones and tail vertebrae made their way here in 1991, followed by a partial braincase in 1998. Another ilium from South Dakota arrived in 2000, but that has since been lost and may actually belong to the Portuguese tyrant's grandmother: Aviatyrannis.
Stokesosaurus and Tanycolagreus are about the same size, and the pair may be synonymous. But that's tough to prove when the former is anchored by an ilium that wasn't attached to any other bones while the latter is known from other bones that aren't attached to an ilium. Furthermore, Rauhut named Aviatyrannis in 2003 for an ilium from a Portuguese coal mine that he had previously assigned to Stokesosaurus, with some experts unconvinced by its separation. The irony of the tyrant's grandmother being based on a hip replacement is not lost on us.
If the previously mentioned trio represent the same critter, Tanycolagreus will be first for the chop as it was named last, followed by Aviatyrannis regardless of her actual age. In biological nomenclature, the science of naming organisms, it's the first coined name that counts (unless you're Tyrannosaurus or Allosaurus), which would make Stokesosaurus the only valid name for all three.
(Stokes' lizard from the Cleveland-Lloyd Quarry)Etymology
Stokesosaurus is derived from "stokes" (in honor of Utah geologist William Lee Stokes) and the Greek "sauros" (lizard). The species epithet, clevelandi, refers to its discovery in the Cleveland-Lloyd Dinosaur Quarry.
Discovery
The remains of Stokesosaurus were discovered at the Cleveland-Lloyd Dinosaur Quarry in the Brushy Basin Member of the Morrison Formation, Emery County, Utah, USA, by William Lee Stokes and James Madsen, sometime between 1960-1970.
The holotype, UMNH 2938 (formerly UUVP 2938), is a hip bone (ilium), 220 mm long.
