Arthropod trackways and their preservational variants from the Bagh Formation (Upper Cretaceous), India

Abstract

Tidal siliciclastic deposits of the Turonian Nimar Sandstone (Bagh Formation), India, contain several arthropod trackways which have been ascribed to different ichnogenera by Chiplonkar and Badve (1970). Examination of their type material along with additional material from the same deposits allows a revision of these ichnotaxa. As a result, Oniscoidichnus communis Chiplonkar and Badve, 1970 is retained, and Oniscoidichnus ampla Chiplonkar and Badve, 1970, O. elegans Chiplonkar and Badve, 1970, O. robustus Chiplonkar and Badve, 1970, Dreginozoum orientale Chiplonkar and Badve, 1970, Nereites malwaensis Chiplonkar and Badve, 1970, Arthropodichnus indicus Chiplonkar and Badve, 1970, Tasmanadia sp. indet., and Permichnium bosei Chiplonkar and Badve, 1970, are treated as its subjective synonyms. Their morphological differences are treated as morphological variants of the same trace fossils, with several transitions between them, which resulted from minor changes in behavior of the tracemaker, changes in substrate properties and preservation. The morphological features of the O. communis point to a tracemaker having segmented locomotion appendages, segmented carapace, and a short abdomen, which was probably an isopod. Supposedly, the same tracemaker produced the associated Rusophycus ispp. A, B, cf. Rusophycus ispp. C, D and the chevron traces A, B, C, D and E. Diplopodomorpha cretaceca Chiplonkar and Badve, 1970 is maintained as a separate ichnogenus and ichnospecies being a trackway of an unknown arthropod.