| Saltopus | |
|---|---|
 | |
| Holotype elements | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauromorpha |
| Clade: | Dinosauriformes |
| Clade: | Dracohors |
| Genus: | †Saltopus von Huene,1910 |
| Species: | †S. elginensis |
| Binomial name | |
| †Saltopus elginensis von Huene, 1910 | |
Saltopus ("hopping foot") is a genus of very small bipedaldinosauriform containing thesinglespeciesSaltopus elginensis from the lateTriassic period ofScotland.[1] It is one of the most famousElgin Reptiles.
Saltopus elginensis is known only from a single partial skeleton lacking the skull, but including parts of the vertebral column, the forelimbs, the pelvis and the hindlimbs. These have been mainly preserved as impressions or natural casts in the sandstone; very little bone material is present.[1] It was about the size of a domestic cat, and would have been roughly 80–100 centimetres (31–39 in) long.[2] It had hollow bones like those of birds and other dinosaurs. It may have weighed around 1 kilogram (2.2 lb). In 2016, it was estimated to be 50 cm long, 15 cm high at the hips, and 110 g.[3] Most of the length was accounted for by the tail. It had five-fingered hands, with the fourth and fifth finger reduced in size. Contrary to the original description, in 2011 it was established that thesacrum (hip vertebrae) was made up of two vertebrae, the primitive ancestral condition, not four.[2]
The only knownfossil ofSaltopus was discovered in 1867 byWilliam Taylor in theLossiemouth West & East Quarries. It was initially named as a specimen ofTelerpeton elginense (nowLeptopleuron lacertinum) byThomas Henry Huxley in 1867,[4] and it was later named and described byFriedrich von Huene in 1910 as thetype speciesSaltopus elginensis.[1]
The generic name is derived fromLatinsaltare, "to jump" and Greek πούς,pous, "foot". Thespecific name refers to its provenance nearElgin, which yields theElgin Reptiles. TheholotypeNHMUK R.3915, was excavated from theLossiemouth Sandstone Formation dating from theCarnian-Norian stage.[1]
Saltopus has been variously identified as asaurischian (lizard-hipped) dinosaur, a more advancedtheropod, and a close relative of theherrerasaurs, but itstaxonomy has been in dispute because only fragmentary remains have been recovered.[5] Some researchers, such asGregory S. Paul,[6] have suggested it may represent a juvenile specimen of acoelophysid theropod such asCoelophysis orProcompsognathus. Rauhut and Hungerbühler in 2000 concluded it is a primitive dinosauriform, not a true dinosaur, closely related toLagosuchus.[7]Michael Benton, continuing the studies of the lateAlick Walker redescribing the fossil in 2011, found it to be adinosauriform more derived thanLagosuchus.[2]
A large phylogenetic analysis of early dinosaurs and dinosauromorphs by Matthew Baron,David B. Norman and Paul Barrett (2017) recoveredSaltopus near the base of the dinosaur lineage, suggesting that it may represent the closest relative of true dinosaurs.[8]
