<EM>Bifurculapes</EM> Hitchcock 1858: a revision of the ichnogenus

Abstract

Characters differentiating the arthropod trackway Bifurculapes from the similar ichnogenera Lithographus and Copeza include the position, arrangement and orientation of the tracks within the series. Of the five species of Bifurculapes originally described, only Bifurculapes laqueatus and Bifurculapes scolopendroideus are recognized herein; the other three ichnospecies are considered to be nomina dubia or junior subjective synonyms of Bifurculapes laqueatus. Two new specimens, recovered from the Early Jurassic East Berlin Formation of the Hartford Basin in Holyoke, Massachusetts, represent only the second unequivocal occurrence of the ichnogenus outside of the Deerfield Basin. Bifurculapes is currently known only from the Early Jurassic. RÉSUMÉLes caractéristiques qui différencient la piste d'arthropode Bifurculapes des ichnogenres Lithographus et Copeza similaires sont la position, la disposition et l' orientation des traces à l'intérieur de la série. Parmi les cinq espèces de Bifurculapes originalement décrites, seules Bifurculapes laqueatus et Bifurculapes scolopendroideus sont ici reconnues. Les trois autres ichnoespèces sont considérées comme nomina dubia ou comme synonymes subjectifs plus récents de Bifurculapes laqueatus. Les deux nouveaux spécimens trouvés dans la formation du Jurassique précoce d'East Berlin dans le bassin de Hartford, à Holyoke, au Massachusetts, représentent seulement la seconde présence sans équivoque de l'ichnogenre à l' extérieur du bassin de Deerfield. À l'heure actuelle, Bifurculapes n' est associé qu'au Jurassique précoce.

A trace fossil made by a walking crayfish or crayfish-like arthropod from the Lower Jurassic Moenave Formation of southwestern Utah, USA

“…(B) Asaphoidichnus trifidus (traced from Miller, 1880 ). (C) Bifurculapes laqueatus (traced from Getty, 2016 ). (D) Coenobichnus currani (traced from Walker, Holland & Gardiner, 2003 ).…”

“…Kouphichnium , are also present. Ichnospecies of Bifurculapes have been variably attributed to insects, possibly beetles, and to crustaceans ( Getty, 2016 , 2018 ; Hitchcock, 1858 , 1865 ); ichnospecies of Diplichnites have been attributed to myriapods ( Briggs, Rolfe & Brannan, 1979 ; Davis, Minter & Braddy, 2007 ; Pollard, Selden & Watts, 2008 ; Shillito & Davies, 2018 ), notostracans ( Lucas et al, 2006a ; Minter et al, 2007 ), and other arthropods ( Melchor & Cardonatto, 2014 ; Minter et al, 2007 ); and ichnospecies of Kouphichnium have been attributed to limulids ( Caster, 1944 ; King, Stimson & Lucas, 2019 ; Lomax & Racay, 2012 ).…”

Revision of the Early Jurassic arthropod trackways Camurichnus and Hamipes

“…Most subsequent workers (e.g., Hitchcock, 1889;Lull, 1915Lull, , 1953Mayoral, 2001) have also considered Bifurculapes to be an insect trackway. Getty (2016) suggested that the species B. laqueatus was likely the work of insects, and noted that the darkling beetle (Coleoptera: Tenebrionidae) trackways illustrated by Eiseman and Charney (2010) are similar to that ichnospecies. Demathieu et al (1992), however, argued that possible specimens from France were most likely made by a triopsid crustacean, and de Gibert et al (2000) proposed that their specimens were most likely made by astacid decapods.…”

“…C. H. Hitchcock (1889) reported Sagittarius, which is herein considered a junior subjective synonym of Bifurculapes, from Connecticut and New Jersey. Getty (2016) also reviewed the tentative occurrences of Bifurculapes from the Permian of France and Italy (Demathieu et al, 1992;Durand, 2001;Santi, 2006), the Triassic of Argentina (Melchor 2004), the Jurassic of Utah (Lucas et al, 2006;Milner et al, 2009), and the Cretaceous of Alaska (Fiorillo et al, 2009). He concluded that of these, the only specimen that should be included within Bifurculapes based on the information provided in the papers describing them was the one from Utah.…”

“…Demathieu et al (1992), however, argued that possible specimens from France were most likely made by a triopsid crustacean, and de Gibert et al (2000) proposed that their specimens were most likely made by astacid decapods. Getty (2016) suggested that Bifurculapes scolopendroideus, which is much larger than B. laqueatus, might have been produced by a crustacean based on its presence in lacustrine shale. Thus, it appears that different species of Bifurculapes might have had different makers.…”