Pronunciation: chwahn-DONG-o-see-LOOR-us
Meaning: Chuandong hollow tail
Author/s: He (1984)
Synonyms: None known
First Discovery: Sichuan Province, China
Discovery Chart Position: #309
Chuandongocoelurus primtivus
Sporting features typical of 'advanced' theropods known as tetanurans in its shins, features of more 'primitive' theropods known as, well, not tetanurans, in its thighs, and features of both in its hips, Chuandongocoelurus is something of an enigma. Its mosaic anatomy blurs the clean lines that palaeontologists try to draw between early theropods and those that came later, leaving it perched awkwardly at the threshold of definition. Over the years, it has been shuffled between Coeluridae, Theropoda indeterminate, Megalosauroidea, and Tetanurae proper—but at a bet-hedging position close to the root of the family tree, reflecting how little consensus its fragmentary remains have inspired.
Funnily enough, a hip bone and a few back bones—the only comparable parts preserved in both Chuandongocoelurus and the equally troublesome Monolophosaurus—show the same mix of old and new features. In fact, the two differ only in size, with the former much smaller than the latter, and not simply because it wasn’t fully grown. This suggests they may have been variations on a single anatomical theme rather than wholly distinct evolutionary experiments, perhaps each other's closest relative or, at a stretch, two specimens of the same critter.
Funnily enough, a hip bone and a few back bones—the only comparable parts preserved in both Chuandongocoelurus and the equally troublesome Monolophosaurus—show the same mix of old and new features. In fact, the two differ only in size, with the former much smaller than the latter, and not simply because it wasn’t fully grown. This suggests they may have been variations on a single anatomical theme rather than wholly distinct evolutionary experiments, perhaps each other's closest relative or, at a stretch, two specimens of the same critter.
(Primitive Chuandong hollow tail)Etymology
Chuandongocoelurus is derived from "Chuandong" (its place of discovery) and the Greek "koilos" (hollow) and "oura" (tail). It was named as a supposed Chinese version of the problematic North American theropod, Coelurus ("hollow tail"). The species epithet, primtivus, means "the primitive one" in Latin.
Discovery
The remains of Chuandongocoelurus were discovered in the Xiashaximiao
Formation at the township of Chuandong, Zigong City, Sichuan Province, China.Strictly speaking, the holotype (CCG 20010) is a thigh, but two neck vertebrae, two back vertebrae, one tail vertebra, a partial shoulder blade, a partial pelvis, a shin, an ankle, a heel, and nine foot bones were catalogued under the same specimen number and may belong to the same subadult individual.
He also referred a second specimen (CCG 20011: neck vertebrae) to Chuandongocoelurus in 1984, but this material is stupendously large compared to the holotype and appears to share more similarities with a ceratosaur called Elaphrosaurus. It was identified as an all new species of noasaurid ceratosaur in the thesis of Josef Stiegler in 2019, but he refrained from formally naming it.
