The IchnogenusKouphichniumand Related Xiphosuran Traces from the Steven C. Minkin Paleozoic Footprint Site (Union Chapel Mine), Alabama, USA: Ichnotaxonomic and Paleoenvironmental Implications

Abstract

The ichnogenus Kouphichnium and associated ichnofossils attributed to xiphosuran activity are here reexamined from samples collected from the Pennsylvanian-age Steven C. Minkin Fossil Site at the Union Chapel Mine, in Walker County, Alabama, USA. The large sample size offers an unique opportunity to evaluate some Kouphichnium ichnospecies. Thus, the morphological variability resulting from the taphonomic, ethological, taxonomic variability and underprint fallout are evaluated using this large sample set. Three morphotypes have been segregated from the material previously assigned to K. aspodon discovered at this and adjacent sites. Ichnospecies of Kouphichnium identified at the Union Chapel Mine site include: K. lithographicum, K. aspodon and two new ichnospecies (K. atkinsoni and K. minkinensis). Additionally, Kouphichnium-like traces that are associated with "jumper" traces have been previously misinterpreted as Kouphichnium and Selenichnites, respectively, and are excluded from this study, leaving them in open nomenclature as they will be the subject of a subsequent publication. We here redescribe the holotype of K. aspodon and designate lectoparatypes to better define the ichnospecies. New trace makers for some Kouphichnium ichnospecies are hypothesized, in contrast to the traditional xiphosuran attribution.

Horseshoe crab trace fossils from the Upper Cretaceous Two Medicine Formation of Montana, USA, and a brief review of the xiphosurid ichnological record

“…Examples of the former include trackways from the Bude Formation of England (Tyler, 1988) and the Parrsboro Formation of Nova Scotia (Goldring and Seilacher, 1971). Other trackways may have a more chevron-like arrangement of the simple tracks but medially placed pushers (Fillmore et al, 2010; King et al, 2019) or the opposite condition, a perpendicular line of simple tracks and laterally placed pushers (Eagar et al, 1985). Others differ still in having tracks concentrated into two separate columns, as in Kouphichnium aspodon (Buta et al, 2005; Lucas and Lerner, 2005).…”

“…External widths of both trackways and resting traces show a wide range in the Carboniferous and earlier. Many are less than 4 cm wide (Caster, 1938; Fischer, 1978; Chisholm, 1983; Tyler, 1988; Fillmore et al, 2010), but others range to over 8 cm and up to 13 cm wide (Romano and Melendez, 1985; Conti et al, 1991; King et al, 2019). Small traces are much rarer, particularly in the Mesozoic and Cenozoic (Moreau et al, 2014), seeming to reflect the general loss of small and differently shaped taxa.…”

“…Overall, horseshoe crabs have a rich ichnological record that highlights a number of behaviors. Several works provide excellent images of the diversity to be found among the trackways (e.g., Moreau et al, 2014; Shu et al, 2018; King et al, 2019), with Buta et al (2005) providing an extensive photographic atlas of the traces from the Carboniferous Pottsville Formation of Alabama.…”

“…Three recent papers address the ichnotaxonomy of Kouphichnium and other horseshoe crab traces: Gaillard (2011), Shu et al (2018), and King et al (2019). Gaillard (2011) focused on four behaviors (walking, crawling, dying, and ploughing) and the trackway features that characterize these actions.…”

“…Types IV and VI would have no equivalent in the Shu et al (2018) scheme. King et al (2019) undertook a review of Kouphichnium using the abundant traces from the Stephen C. Minkin Paleozoic Footprint Site of the Carboniferous Pottsville Formation of Alabama. They recognized several new species but also considered some species within the genus to correspond to non-xiphosurans.…”