Redescription of the ichnospecies Antipus flexiloquus Hitchcock, from the Early Jurassic of the Connecticut Valley

Abstract

Many ichnological taxa named by Edward Hitchcock have never been adequately described and illustrated. Among these is the ichnogenus Antipus Hitchcock (1858, p. 115) with two species: A. flexiloquus based on specimens AC (=Amherst College, Amherst, Massachusetts) 35/25 and AC 41/52 (designated the type specimen by Lull 1904, p. 536); and A. bifidus based on specimens AC 23/3, AC 17/2, and AC 23/2 (designated the type specimen by Hitchcock 1865, p. 56). Lull (1904, p. 536) regarded A. bifidus as “… extremely doubtful…” and did not consider it in later publications (e.g., Lull 1915, 1953). The impressions ascribed to A. bifidus might be organic in origin, but if they are trackways, they are totally unlike the tracks of A. flexiloquus. Antipus bifidus is here regarded a nomen dubium because it is undiagnostic. Referred specimen AC 35/25, a small, thin slab of micaceous shale (approximately 87 mm by 96 mm, less than 2 mm thick) that is not mentioned by Lull (1904, 1915, 1953), has one manus and possibly one pes track of such poor quality that analytic comparison to the type of A. flexiloquus is impossible. Therefore, the ichnogenus Antipus has a single species, A. flexiloquus, known only from the type specimen, AC 41/52. Two of the eleven tracks on AC 41/52 have been illustrated (Hitchcock 1858, plate 20, fig. 10; republished with minor revision by Lull 1915, fig. 117; these two tracks are here designated M2 and P4). These simple outline sketches do not accurately portray details of the tracks, and the full trackway pattern was not illustrated.