Mesoproterozoic megafossil Chuaria– Tawuia association may represent parts of a multicellular plant, Vindhyan Supergroup, Central India

Abstract

Nine megafossils are described from about 1 billion-year-old Suket Shale of the Semri Group (lower Vindhyan), Rampura area, Neemuch district, Madhya Pradesh. Eight are carbonaceous megafossils representing eight species belonging to six genera, while one megafossil is described informally as form A. The megafossils are Chuaria circularis Walcott, Chuaria vindhyanensis sp. nov., Tawuia dalensis Hofmann, Tawuia indica sp. nov., Suketea rampuraensis gen. and sp. nov., Tilsoia khoripensis gen. and sp. nov., Chambalia minor gen. and sp. nov., Beltina danai Walcott and Form A. There is a definite relationship between C. circularis, Tawuia and Tilsoia. They appear to constitute three different parts of a multicellular Chlorophycean/Xanthophycean plant; (a) C. circularis represents a compressed cyst like spherical body which was attached with a siphonaceous/filamentous thallus, (b) the siphonaceous/filamentous thallus was preserved as Tawuia and (c) the thallus was also attached to a frustum like body named as Tilsoia which acted as a holdfast apparatus. C. vindhyanensis sp. nov. is smaller form and interpreted to represent spore like bodies, which were released by C. circularis on maturation. S. rampuraensis represents circular compression with a circular rim and is interpreted to be a transversely compressed Tilsoia. The extinct plant is named as Radhakrishnania. Two species Radhakrishnania major and Radhakrishnania minor are recognised on the basis of size. Chambalia minor gen. and sp. nov. is considered a Chlorophycean plant. Chuaria, Tawuia and Grypania are all reported from the same stratigraphic horizon and thus they constitute a single biozone.