| Geranosaurus | |
|---|---|
 | |
| Holotype jaw | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | †Ornithischia |
| Family: | †Heterodontosauridae |
| Genus: | †Geranosaurus Broom,1911[1] |
| Type species | |
| †Geranosaurus atavus Broom, 1911 | |
Geranosaurus (meaning "crane reptile") is agenus ofheterodontosauridornithischiandinosaur from theEarly Jurassic. The type and only species isG. atavus.
During the road-cutting ofBarkly Pass inEastern Cape, South Africa, road engineer George Mandy collected the remains of a small dinosaur, including badly crushed fragments of theskull, partial limb bones, andvertebrae. These fossils were acquired by theSouth African Museum and subsequently described in1911 by South African palaeontologistRobert Broom. Broom found that the fossils represented the earliest known member ofPredentata and gave them the nameGeranosaurus atavus, though he was uncertain if all the bones were from a single individual and as a result treated the partial skull as theholotype.[1] Noetymology for the name was provided, but for thespecies name theLatin wordatavus means "ancestor" referencing its position as an early ornithischian, and of thegenus namegeranos isAncient Greek for "crane" in reference to the bird-like limb bones.[2] The holotype bears the collection number SAM-PK-1871, while the poorly preserved partial hindlimb is numbered as SAM-PK-1857. The vertebrae were believed to be too large to be from the same individual as the skull, but are now lost.[1][3]
The discovery ofGeranosaurus was interpreted by Broom as being within the CaveSandstone of theStormberg Series,Early Jurassic in age. Though it had previously been consideredTriassic, even an Early Jurassic age would makeGeranosaurus the oldest ornithischian.[1] The "Cave Sandstone" is now known as theClarens Formation, with the approximate coordinates of the locality along the road cutting being31°27′S27°51′E / 31.450°S 27.850°E /-31.450; 27.850 placingGeranosaurus within the lower portion of the formation.[4]Uranium-lead dating of the top of the Clarens Formation and top of the underlyingElliot Formation give the former a mainlyPliensbachian age between 191.1 and 187.5million years ago.[5]
Geranosaurus was around 0.6 metres (2.0 ft) tall and around 1.2 metres (3.9 ft) long when fully grown.[6][1]
Geranosaurus is classified as an ornithischian based on the jaw, probably aheterodontosaurid distinct fromHeterodontosaurus[6] but not a heterodontosaurine.[7] Because of its limited remains,Geranosaurus is generally considered anomen dubium,[6] but it may be distinct because it has the unique combination of an enlargeddentarycaniniform, which is a synapomorphy of Heterodontosauridae, and no post-caniniformdiastema, which excludes it from Heterodontosaurinae.[7]
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