On the Ichnotaxonomic Status of Haplotichnus indianensis (Miller, 1889)

ABSTRACT

The type specimens of the ichnospecies Haplotichnus indianensis and Treptichnus bifurcus were compared under low-angle light. H. indianensis was found to exhibit segments with projections, which are morphological characteristics of T. bifurcus. Consequently, H. indianensis is reinterpreted here as a shallow, subsurface burrow and is considered to be a subjective junior synonym of T. bifurcus. Traces assigned to H. indianensis, other than the type, should be reassigned to other ichnotaxa. Looping surface trails, for example, should be called Gordia isp.

KEYWORDS:

• Carboniferous
• Ichnology
• Plangtichnus
• Taxonomy
• Treptichnus

Acknowledgments

Thanks are due to Paul Mayer of the Chicago Field Museum, for sending the type specimens of Haplotichnus indianensis and Treptichnus bifurcus, and to David Polly of Indiana University, for sending topotypes of T. bifurcus. Additionally, we express our deep thanks to Andrew Rindsberg and Luis Buatois for reviewing this manuscript and providing useful comments that greatly improved the final draft.