''Saltopus'' ("hopping foot") is a genus of very small bipedal

dinosauriform Dinosauromorpha is a clade of avemetatarsalian archosaurs (reptiles closer to birds than to crocodilians) that includes the Dinosauria (dinosaurs) and some of their close relatives. It was originally defined to include dinosauriforms and lage ...

containing the single

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...

''Saltopus elginensis'' from the late

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest per ...

period of

Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to ...

. It is one of the most famous

Elgin Reptiles Elgin Reptiles is the name given to the Permian and Triassic fossils found in the sandstone deposits in and around the town of Elgin, in Moray, Scotland. They are of historical and scientific importance, and many of the specimens are housed in the ...

Description

''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.Huene, F.R. von (1910). "Ein primitiver Dinosaurier aus der mittleren Trias von Elgin." ''Geol. Pal. Abh. n. s.'', 8: 315-322. It was about the size of a domestic cat, and would have been roughly long. It had hollow bones like those of birds and other dinosaurs. It may have weighed around . In 2016, it was estimated to be 50 cm long, 15 cm high at the hips, and 110 g. 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 the

sacrum The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part o ...

(hip vertebrae) was made up of two vertebrae, the primitive ancestral condition, not four.

History

The only known

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

of ''Saltopus'' was discovered by William Taylor in the Lossiemouth West & East Quarries. It was named and described by

Friedrich von Huene Friedrich von Huene, born Friedrich Richard von Hoinigen, (March 22, 1875 – April 4, 1969) was a German paleontologist who renamed more dinosaurs in the early 20th century than anyone else in Europe. He also made key contributions about v ...

in 1910 as the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specim ...

''Saltopus elginensis''. The generic name is derived from

Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...

''saltare'', "to jump" and Greek πούς, ''pous'', "foot". The specific name refers to its provenance near Elgin, which yields the

. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...

NHMUK R.3915, was excavated from the

Lossiemouth Sandstone The Lossiemouth Sandstone is a Middle to Late Triassic (Ladinian to Norian) age geological formation. It is exposed on the south side of the Moray Firth near Lossiemouth and near Golspie in Sutherland. Dinosaur remains are among the fossils th ...

Formation dating from the

Carnian The Carnian (less commonly, Karnian) is the lowermost stage (stratigraphy), stage of the Upper Triassic series (stratigraphy), Series (or earliest age (geology), age of the Late Triassic Epoch (reference date), Epoch). It lasted from 237 to 227 m ...

Norian The Norian is a division of the Triassic Period. It has the rank of an age ( geochronology) or stage (chronostratigraphy). It lasted from ~227 to million years ago. It was preceded by the Carnian and succeeded by the Rhaetian. Stratigraphic ...

stage.

Classification

''Saltopus'' has been variously identified as a saurischian (lizard-hipped) dinosaur, a more advanced

theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...

, and a close relative of the herrerasaurs, but its

taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

has been in dispute because only fragmentary remains have been recovered. Some researchers, such as Gregory S. Paul,Paul, G.S. (1988). ''Predatory Dinosaurs of the World.'' New York: Simon and Schuster. 464 pp. have suggested it may represent a juvenile specimen of a coelophysid theropod such as '' Coelophysis'' or '' Procompsognathus''. Rauhut and Hungerbühler in 2000 concluded it is a primitive dinosauriform, not a true dinosaur, closely related to '' Lagosuchus''.Rauhut, O.M.W. and A. Hungerbühler. (2000). "A review of European Triassic theropods." ''Gaia'', 15: 75-88.

Michael Benton Michael James Benton One or more of the preceding sentences incorporates text from the royalsociety.org website where: (born 8 April 1956) is a British palaeontologist, and professor of vertebrate palaeontology in the School of Earth Sciences ...

, continuing the studies of the late

Alick Walker Alick Donald Walker (26 October 1925 – 4 December 1999) was a British palaeontologist, after whom the '' Alwalkeria'' genus of dinosaur is named. He was born in Skirpenbeck, near York and attended Pocklington School from 1936 to 1943. He began ...

redescribing the fossil in 2011, found it to be a

more derived than '' Lagosuchus''.Michael J. Benton and Alick D. Walker†. 2011. "''Saltopus'', a dinosauriform from the Upper Triassic of Scotland", ''Earth and Environmental Science Transactions of the Royal Society of Edinburgh'', Volume 101, Special Issue 3-4, pp 285 - 299 Royal Society of Edinburgh 2011. Published online: 17 May 2011 A large phylogenetic analysis of early dinosaurs and dinosauromorphs by Matthew Baron,

David B. Norman David Bruce Norman (born 20 June 1952 in the United Kingdom) is a British paleontologist, currently the main curator of vertebrate paleontology at the Sedgwick Museum, Cambridge University. From 1991 to 2011, Norman has also been the Sedgwick Mu ...

and Paul Barrett (2017) recovered ''Saltopus'' near the base of the dinosaur lineage, suggesting that it may represent the closest relative of true dinosaurs.Baron, M.G., Norman, D.B., and Barrett, P.M. (2017). A new hypothesis of dinosaur relationships and early dinosaur evolution. ''Nature'', 543: 501–506.

References

External links

A photograph of the sandstone slab showing the only known ''Saltopus'' specimen, published by the twitter account of the Barret Lab at the London Natural History Museum

The counterpart of the ''Saltopus'' slab, from the same source
{{Taxonbar, from1=Q132859, from2=Q20719247 Prehistoric dinosauromorphs Late Triassic reptiles of Europe Triassic Scotland Fossils of Scotland Fossil taxa described in 1910 Taxa named by Friedrich von Huene 1910 in Scotland History of Moray