Revision of Cassiduloid genusGongrochanus Kier (Echinodermata: Echinoidea) from South Indian Cretaceous deposits

Abstract

Revision of the genus Gongrochanus Kier from Upper Cretaceous beds of South India has revealed the presence of seven species including its type species G. herschelianus (M'Clelland). On the basis of phyllode characters the species have been divided into two informal groups. A biometrical analysis by applying the Bartlett's and F-test proves the validity of the species described. Coefficients of correlation and regression computed for parameters of length, width and height for G. herschelianus are dependent upon one another; that change of length versus width is more regular than that of length versus height. Occurrence of this genus in Hauriceras rembda zone and Pachydiscus otacodensis zone of Kallankurichchi and Ottakkovil formations respectively of Ariyalur Group helps in rectifying its geological age which now can be taken as extending from Lower Maestrichtian to Middle Maestrichtian instead of Senonian.

First report of Eocene echinoids from the Sylhet Limestone, Mikir Hills of Assam, India: palaeontological, palaeogeography and palaeoenvironmental significance

“…In India, d’Archiac and Haime (1853) were the first to record the genus Echionolampas from the Eocene of Kachchh. Echinoids have also been reported from other parts of India like Meghalaya (Das & Bora, 1981; Srivastava & Garg, 2014), Mizoram (Tiwari & Jauhri, 2014), Assam (Spengler, 1923), Gujrat (Srivastava & McNamara, 2011), Himachal Pradesh (Reed, 1910), Tamil Nadu (Badve & Aziz, 1983) and Rajasthan (Srivastava & Mathur, 1996). The present study has been carried out in the Dillai Parbat limestone quarry, which lies on the southeastern edge of the Mikir Hills (Figure 1).…”