Dromopus

''Dromopus'' is a reptilian ichnogenus commonly found in assemblages of ichnofossils dating to the late Pennsylvanian (Moscovian stage) to the late Permian (Changhsingian 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 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 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, ''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 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 Araeoscelidia and the parareptilian Bolosauridae.

References

{{Taxonbar, from=Q96376648

Reptile trace fossils