Triploblastic Animals Aren't Explosive: Or, Studying Really Old Mud

"Triploblastic animals more than 1 billion years ago: trace fossil evidence from india"
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., via PubMed, U.S. National Library of Medicine, National Institutes of Health (October 2, 1998)

"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...."

About the odd capitalization - or lack of same - in the title? The Lemming's just showing what's on the original page.

About triploblastic animals, and the Mesoproterozoic Chorhat Sandstone? Don't let the name fool you. There's nothing explosive about triploblastic animals.

They're not made of plastic, either. The name describes the number of layers they've got at a particular stage of development: It's what you call "...an animal which, as an embryo, had three distinct embryonic tissue layers - the ectoderm, mesoderm, and endoderm. This is in contrast to animals which are diploblastic (has two distinct tissue layers) and those which do not have any distinct tissue layers as an embryo (nor organs and distinct tissues as an adult)." (websters-dictionary-online.com)

There's more to it than that - there always is, it seems - but that'll do for starters.

Now, about that article. The Lemming found a more complete version, on the Bellmarine University (Louisville Kentucky) website:

"Triploblastic Animals More Than 1 Billion Years Ago: Trace Fossil Evidence from India"
Adolf Seilacher, Pradip K. Bose, Friedrich Pflüger, Science (April 24, 1998; accepted July 29, 1998)

"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..."

"...There are two seemingly contradictory views about the early history of metazoans. The 'Cambrian explosion' scenario is based on Cambrian shelly fossils and Burgess-type lagerstätten. This scenario suggests that animal phyla originated rather suddenly ~540 million years ago (Ma) during the Proterozoic-Phanerozoic transition. This view was first modified by the discovery of Ediacaran fossils of late Proterozoic (Vendian) age ... These discoveries lengthened the paleontological record of animals to ~580 Ma. The alternative 'slow burn' scenario suggests that animals developed more slowly (4)--according to some molecular analyses (5), beginning more than 1 billion years ago (6).

"These two scenarios are not incompatible, because they are based on different concepts..."

That'll give an indication of what you'll find there. The Bellmarine U. online article includes illustrations - and is fairly interesting. If you're interested in that sort of thing.

Which the Lemming is.

Your experience may vary.

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