Thursday, 22 May 2014

Cretaceous Flora Fossils near Madras

I visited Gunduperumbedu village near Sriperumbudur last friday, with Gaman Palem and his friend. There were lots of chipped stones on the ground scattered around a pond, and near a graveyard. It seemed they have dug up the soil around these parts for building roads, tanks etc and these stones are deposited all over the place.

I had gone there after reading an old report in the Hindu that plant fossils were embedded in these stones. Our friend in Ahmedabad, Ramjee Nagarajan, helped by sending a document, ‘An Integrated Inquiry of Early Cretaceous Flora, Palar Basin, India,’ published in the journal Phytomorphology, which was interesting, but difficult to follow, since I was ignorant of geology, both practical and theoretical.

After visiting the wrong Gunduperumbedu - there are two, Medu மேடு (Upper) and Pallam பள்ளம் (Lower), the latter with the fossils, we stumbled upon these. Usually old fossils are buried deep under the earth and cannot be seen above the surface. In Dholavira, one of the ASI staff told us that the archaeologists don't pick up and study any pottery on the surface, as it may be recent. They only study things buried under ground. That is for a scale of a few thousand years.

Gunduperumbedu - scattered stones on mound

Close up of stones

The paper talked of Cretaceous Flora, which is the geological period, when flowering plants evolved, about 150 million years ago. But the preamble mentioned pre-angiospermic flora and plant megafossils!

And it also mentioned that the Palar basin had:

1.    Archaean deposit - more than 2 billion years ago, before there was cholorophyll or plants,
2.    PreCambrian layer. The Cambrian “explosion”, 500mya, was the single largest evolutionary event. There were only three phyla before it, and there are 42 afterwards. It saw the largest increase in the number of animal species. PreCambrian fossils are extremely rare.
3.    Permian layers. The end of the Permian period saw the greatest extinction ever: 96% of all species became extinct.

TimeLine of Multicellular Life, showing different eras 


I dont know if there are actually any excavations that deep or any fossils in that area that old, or merely geological evidence. We certainly did not see any megafossils. Last year, I was planning to visit the Burgess Shale in Canada & perhaps Ediacaran sites in Australia to see pre-Cambrian sites. In Gujarat, I - ok, we - missed out on the dinosaur fossil site in Balasinore. This is a fossil park protected by Geological Survey of  India.  A large collection of dinosaur eggs was recently discovered in Ariyalur.

The locals told us that people from Pondicherry and Madras come on weekends and take away stones and fossils by the sackful. It is a pity there is no archaeological expedition here. There was once an exhibition in a local school. Local youth scan for fossils and offer them for sale. One person gave Gaman  a stone with a plant fossil and another with a shell, possibly molluscan, fossil. Gaman became excited, believed that it was starter’s luck and it paid off – we found a few afterwards. I decided to search in the shade, and even that strategy paid off. I got one.

Perhaps a Molluscan Fossil - Oyster

Plant fossil

But these are few and far between, and probably not of significant use for serious research. Some of the technical papers mention exploration around borewells, probably because researchers here don’t have budgets or equipment or expertise for excavations. I wanted to post this yesterday, May 21, on Mary Anning's birth anniversary - after seeing her honored with a Google doodle.  Her story is fascinatingly similar to our experience, with far fewer dangers. Her discoveries were accidental, when a landslide uncovered fossils. She pursued the search for fossils, made it into a commercial enterprise, came into contact with experts, and so on. The locals are doing this as a minor commercial enterprise, but land development may overrun this site. Fortunately, the Sriperumbudur bed is a vast area and the Palar basin is even larger.

References
1. ‘An Integrated Inquiry of Early Cretaceous Flora, Palar Basin, India,’ published in the journal Phytomorphology, A. Rajanikanth, Anil Agarwal, A. Stephen (stephanos.crown@gmail.com)
2. Mary Anning, Wikipedia page
3. A blog on dino eggs
4. The timeline map of Life - I dont remember what video I captured if from - either a series by Craig Savage or a lecture by Nick Lane. Both are excellent.

Postscript July 15, 2016 
In this article, published in the Hindu in 2014, Mr Singanejam Sambandan, Director of the Geological Survey of India, Chennai, has observed that the fossils belong to the Upper Gondwana period, 250 MYA, not Cretaceous 150 MYA, as noted in the title of the first listed reference paper by Rajanikantha, Agarwal, Stephen.

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