''Dromopus'' is a reptilian

ichnogenus An ichnotaxon (plural ichnotaxa) is "a taxon based on the fossilized work of an organism", i.e. the non-human equivalent of an artifact. ''Ichnotaxon'' comes from the Ancient Greek (''íchnos'') meaning "track" and English , itself derived from ...

commonly found in assemblages of

ichnofossil A trace fossil, also called an ichnofossil (; ), is a fossil record of biological activity by lifeforms, but not the preserved remains of the organism itself. Trace fossils contrast with body fossils, which are the fossilized remains of part ...

s dating to the late

Pennsylvanian Pennsylvanian may refer to: * A person or thing from Pennsylvania * Pennsylvanian (geology) The Pennsylvanian ( , also known as Upper Carboniferous or Late Carboniferous) is, on the International Commission on Stratigraphy, ICS geologic timesc ...

(

Moscovian Moscovian may refer to: *An inhabitant of Moscow, the capital of Russia *Something of, from, or related to Moscow *Moscovian (Carboniferous) The Moscovian is in the International Commission on Stratigraphy, ICS geologic timescale a stage (strat ...

stage) to the late

Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years, from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It is the s ...

(

Changhsingian In the geologic time scale, the Changhsingian or Changxingian is the latest age or uppermost stage of the Permian. It is also the upper or latest of two subdivisions of the Lopingian Epoch or Series. The Changhsingian lasted from to 251.9 Ma a ...

stage). It has been found throughout Europe, as well as in the United States, Canada, and Morocco. Several ichnospecies have been named; only the type ichnospecies ''D. lacertoides'' is definitively recognized.

History

Species

Originally named as an ichnospecies of '' Saurichnites'' by Hanns Bruno Geinitz in 1861, ''S. lacertoides'' was transferred to the newly created genus ''Dromopus'' by

Othniel Charles Marsh Othniel Charles Marsh (October 29, 1831 – March 18, 1899) was an American professor of paleontology. A prolific fossil collector, Marsh was one of the preeminent paleontologists of the nineteenth century. Among his legacies are the discovery or ...

in 1894, along with a new ichnospecies ''D. agilis'' from the United States. In 1929, Roy Moodie described two-digit traces from the Red Beds of Texas under the ichnospecies '' Varanopus palmatus'', ''V. impressus'', ''V. elrodi'', and ''V. didactylus''. However, these were subsequently considered to represent a single ichnospecies of ''Dromopus'' by William Sarjeant. Because the

type specimen In biology, a type is a particular wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...

of ''V. palmatus'' is broken, and ''V. impressus'' and ''V. elrodi'' are incomplete, ''Dromopus didactylus'' is generally the preferred name. In 1963 and 1964, Paul Ellenberger described many ichnospecies of ''Dromopus'': ''D. neooctavianensis'', ''D. brevidigitatus'', ''D. duidigitatus'', ''D. octavianensis'', ''D. bidigitatus'', ''D. curtidigitus'', ''D. inversidigitulifer'', ''D. rabejacensis'', ''D. rectidigitus'', ''D. rectangulus'', ''D. exsultans'', and ''D. cursor''. Harmut Haubold considered them invalid in a 2000 review. There have been disagreements about whether the North American ''D. agilis'' represents a separate ichnospecies. More recently, based on the fact that there is no satisfactory anatomical diagnosis distinguishing various ichnospecies of ''Dromopus'', only the type ichnospecies ''D. lacertoides'' has been agreed to be valid.

Synonyms

In 1892, Pohlig used the new ichnogenus ''Protritonichnites'' for the ichnospecies ''Saurichnites lacertoides'', before Marsh had named ''Dromopus''. By the principles of

synonymy A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

, ''Protritonichnites'' should have priority over ''Dromopus''. However, in 1970, Haubold argued that this name was largely unused by this point, and it was also based on a less taxonomically sound definition. Although some European researchers during the 1980s persisted in using the name ''Protritonichnites'', ''Dromopus'' has generally found more widespread adoption. Other synonyms include ''Eumekichnium'', named by

Franz Nopcsa Franz may refer to: People * Franz (given name) * Franz (surname) Places * Franz (crater), a lunar crater * Franz, Ontario, a railway junction and unorganized town in Canada * Franz Lake, in the state of Washington, United States – see Fran ...

in 1923, including the type ichnospecies ''E. longipollex'', as well as ''E. gampsodactylum'' and ''E. pachydactylum'' (both formerly ''Ichnium''); and ''Gampsodactylum'', also named by Nopcsa in 1923, including the type ichnospecies ''G. alberdorfense'' as well as ''G. friedrichrodanum'' and ''G. kabarzense''.

Description

''Dromopus lacertoides'' tracks are characterized by five-fingered hand and foot imprints up to long, about a third longer than they are wide, with a short palm and long, slender, tapered digits. The length of the digits increases from the first to the fourth, with the fifth having the same length as the second. The hand and foot imprints are not particularly distinct. ''D. didactylus'' tracks are based on similar tracks, but where the imprints of all but two digits are faint. ''Dromopus'' tracks have been ascribed to lizard-like reptiles, including the

diapsid Diapsids ("two arches") are a clade of sauropsids, distinguished from more primitive eureptiles by the presence of two holes, known as temporal fenestrae, in each side of their skulls. The earliest traditionally identified diapsids, the araeosc ...

Araeoscelidia Araeoscelidia or Araeoscelida is a clade of extinct tetrapods (traditionally classified as diapsid reptiles) superficially resembling lizards, extending from the Late Carboniferous to the Early Permian. The group contains the genera '' Araeosceli ...

and the

parareptilia Parareptilia ("near-reptiles") is an extinct group of basal sauropsids (" reptiles"), traditionally considered the sister taxon to Eureptilia (the group that likely contains all living reptiles and birds). Parareptiles first arose near the en ...

n Bolosauridae.

References

{{Taxonbar, from=Q96376648 Reptile trace fossils