Treptichnus ichnogenus from the Cambrian of India and Bhutan: Its relevance to the Precambrian-Cambrian boundary

Abstract

Treptichnus pedum and the Treptichnus lublinensis (first record from the Himalaya) are reported from the Cambrian successions of the Spiti Valley (Tethyan Himalaya) and the Nigali Dhar syncline (Lesser Himalaya) respectively. The paper also discusses morphological variation, palaeoenvironmental and stratigraphic significance of Treptichnus and revises the known occurrences of Phycodes pedum and/or Treptichnus, synonymous and analogous from the Cambrian of India and Bhutan. In the Himalaya, the record of Treptichnus/Phycodes, including the ichnospecies Treptichnus pedum, is from the Cambrian Series 2, Stage 4 to Furongian (Paibian) part, hence cannot be utilised for demarcating the Precambrian-Cambrian boundary in the Himalaya. The late appearance of Treptichnus ichnogenus in the Cambrian of the Indian Himalaya is attributed to higher latitudinal position of India during the Early Cambrian. As a result, possibly the Treptichnus producing organism, i.e. priapulid worms emerged in the latter part of the Cambrian Series 2, Stage 4 in both the regions.