Triploblastic animals more than 1 billion years ago: trace fossil evidence from india
Some intriguing bedding plane features that were observed in the Mesoproterozoic Chorhat Sandstone are biological and can be interpreted as the burrows of wormlike undermat miners (that is, infaunal animals that excavated tunnels underneath microbial mats). These burrows suggest that triploblastic animals existed more than a billion years ago. They also suggest that the diversification of animal designs proceeded very slowly before the appearance of organisms with hard skeletons, which was probably the key event in the Cambrian evolutionary explosion, and before the ecological changes that accompanied that event.
A. Seilacher, Geologisch-Palaontologisches Institut der Universitat, 72076 Tubingen, Germany, and Department of Geology and Geophysics, Yale University, Box 208109, New Haven, CT 06520, USA. P. K. Bose, Department of Geological Scie.
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