| Aetonyx | |
|---|---|
 | |
| Type specimens ofAetonyx palustris (19–23),Massospondylus harriesi (18), andGeranosaurus (24) | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Eusaurischia |
| Clade: | †Sauropodomorpha |
| Genus: | †Aetonyx Broom,1911[1] |
| Species | |
Aetonyx is adubious genus ofsauropodomorphdinosaur from theEarly Jurassic of southern Africa. Its only species isA. palustris, which was named byRobert Broom in 1911 based on a fragmentary skeleton from theupper Elliot Formation found nearFouriesburg,Free State Province. Broom considered it as a species of "carnivorous dinosaur". In 1924,Sydney H. Haughton assigned a second specimen toAetonyx, which is also from Fouriesburg. In 1932,Friedrich von Huene suggested that the speciesThecodontosaurus dubius, which Haughton had named in his 1924 paper, is asynonym ofAetonyx palustris. The species was later synonymised withMassospondylus harriesi andMassospondylus carinatus. A 2004 review lists it as anindeterminatesauropodomorph.
Aetonyx was named in 1911 byRobert Broom from a fragmentary skeleton excavated by A. R. Walker, who worked at theIziko South African Museum, where the specimen is still stored (specimen number SAM-PK-2768-2770).[1]: 294, 304 [2]: 173 The specimen was found nearFouriesburg,Free State Province, in sediments of theupper Elliot Formation, which was deposited during theHettangian andSinemurian ages of theEarly Jurassic.[2]: 173 [3] The specimen is well-preserved and consists of three neck vertebrae, one back vertebra, somedistal tail vertebrae, a shoulder blade withcoracoid, and parts of the forelimb (humerus,radius,ulna, both hands) and hind limb (the upper end of atibia and an almost complete foot). The humerus was 17.4 cm in length.[4]: 91 The name may be translated as'eagle claw' (from theAncient Greekaetos'eagle' andonyx'claw'), and probably refers to the large claw on the second toe which, according to Broom, resembled those seen in many birds and could have been used for grooming its scales.[5]
Taxa today classified as basalsauropodomorphs, includingAetonyx, have been historically classified astheropods until the mid-twentieth century.[6]: 102 Broom introduced the new taxon as a "carnivorous dinosaur".[1] A second specimen from the same locality was assigned toAetonyx in 1924 bySydney H. Haughton; this specimen consists of the lower end of afibula and three rightmetatarsals.[7][4]: 91 In 1932,Friedrich von Huene classifiedAetonyx within theCarnosauria, noting resemblances to the large carnivorous theropodMegalosaurus. The penultimate phalanges of the hand are elongated inAetonyx, which von Huene thought was an adaptation for capturing prey. He cautioned, however, that only the discovery of a skull can confirm its carnosaurian affinities. Von Huene also declaredThecodontosaurus dubius, a species that Haughton had named in his 1924 paper, to be a synonym ofAetonyx palustris.T. dubius was based on a partlyarticulated (connected) skeleton from theClarens Formation found nearLadybrand, South Africa[4]: 91–93 [8]
In 1970, Rodney Steel still listedAetonyx palustris as a valid taxon, but in 1976,Peter Galton and Michael Albert Cluver proposed that it is a synonym ofMassospondylus harriesi, a species that was named by Broom in 1911, in the same paper that namedAetonyx palustris itself.[9]: 47 [8]: 146 [1] In 1981, Michael Cooper synonymised both species with the type species ofMassospondylus,M. carinatus, which was followed by Galton in a 1990 review.[10][11] In a 2004 review, Galton and Paul Upchurch considered all these remains to be undiagnostic and listedAetonyx palustris,Thecodontosaurus dubius, andMassospondylus harriesi as indeterminate sauropodomorphs (Nomina dubia).[12][2]: 173