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Fishapods : a missing link?

Amitabh Hore*

Department of Zoology, Ranchi University, Ranchi – 835001, Jharkhand, India.

THE PREAMBLE

Till now the origin of primitive four footed land vertebrates (tetrapods) from fish like aquatic ancestors was in the realm of evolutionists’ conjecture. On April 6, 2006 the British journal Nature announced the discovery of a fossil that could be called the missing link between fish and the first land vertebrate. The issue of Nature, with “When Fins Became Limbs” headline on its cover, published two articles variously authored by Shubin, Daeschler and Jenkins describing the new fossil find as that of a creature, which was both ‘a fish and a tetrapod’ jokingly calling it a fishapod’1.

PALAENTOLOGICAL HUNT

Drs Neil H Shubin, Evolutionary Biologist and a Professor of Organismal Biology at the University of Chicago, Ted Daeschler, a Paleontologist and Curator of ┬áVertebrate Biology at the Academy of Sciences in Philadelphia and Farish Jenkins Jr., Professor of Organismic ;Ind Evolutionary Biology in Harvard University, used to go on fossil hunt every summer since last six years (1999)2 in the Devonian- aged rocks of Ellesmere Island, in Nunavut Province of Canada lying within the Arctic circle (Fig. 1), just a thousand kilometers from the North Pole3. The place was ideal for such expeditions as it harbored a rich collection of fossils in its rocks, covered by permafrost and with very little vegetation due to extreme temperature 4. This area in Devonian was a part of the supercontinent Laurentia5, which lay on the equator, enjoyed subtropical, warm balmy climate and had later on drifted within the polar circle. It was an ideal setting to look for the evidences of changes that took place on this globe in the Devonian, more than 375 million of years ago, the time when conquest of land by the aquatic vertebrates started. Ted Daeschler, co-leader of the expedition remarked, “we knew the rocks on Ellesmere Island offered a glimpse into the right time of the period and were formed in the right kinds of environments to provide the potential for finding fossils documenting this important evolutionary transition”6.

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