Observations on archaeopyle type in fossil dinoflagellate cyst species Dingodinium Cerviculum Cookson & Eisenack 1958

Abstract

The archaeopyle type in fossil dinoflagellate cyst species Dingodinium cerviculum Cookson & Eisenack 1958 is interpreted based on the study of a rich suite of well-preserved specimens recovered from subsurface Lower Cretaceous sequence of Palar Basin, southern India. These cysts develop disimilar periarchaeopyle and endoarchaeopyle. The periarchaeopyle is intercalary, involving more than one, probably three, anterior intercalary paraplates with free perioperculum. The endoarchaeopyle is combination type involving all the four apical and three anterior intercalary paraplates. The endoperculum is compound and is represented in two parts, an apical part which is simple, polyplacoid and adnate while the other part comprising intercalary paraplates is polyplacoid, free and probably compound. The archaeopyle formula is suggested to be ?2- 3I/(4A) a3I. In view of these observations, the diagnosis of D. cerviculum is emended herein.