IN THE NEWS
August 1, 2013
PUBLISHED: Middle Devonian (Givetian) sharks from Cairo, New York (USA): Evidence of early cosmopolitanism
Collaboration between researchers at the University of Quebec-Rimouski and New York State Museum staff has led to completion of a study on the global distribution of fossil sharks. The fossil shark material described in the report consists of tiny dermal teeth recovered from a large quarry on the northern flank of the Catskill Mountains. "Dermal teeth" are present in most sharks, and make for a sand-paper like feel of their skin. This report is presently on line and will shortly be published in print form.
A very important contribution was made in the early 1900s by New York State Museum Director John M. Clarke. He concluded that major groups of Middle Devonian-age (c. 365 million years ago) marine fossils known in New York appeared earlier significantly earlier in the Devonian of the Amazon Basin of South America and only later spread into North America. This pattern of changes in paleogeographic distribution was shown in 2007, when specimens of Earth's fossil tree were shown to be found in Venezuela and eastern New York State. Now, fossil sharks first described from Antarctica have also been found in eastern New York.
These discoveries reflect the fact that vast tectonic forces that shift parts of the Earth's crust around were serving to bring the giant Gondwana paleocontinent (which included South America, Africa, and Antarctica) close to the southern and eastern margin of ancient North America. By the Middle Devonian, the combined South American and African margin of west Gondwana and southern North America were so close that marine invertebrate animals, spores of early trees, and sharks were crossing into North America. As a result, marine and land communities were transformed in North America with new plant and animal immigrants. By the later Carboniferous Period, the South American and African margins of Gondwana collided with ancestral North America and uplifted the Appalachian and Ouachita mountains.
As of August, 2013, the paper is available on-line as an uncorrected galley on the Acta Palaeontologica Polonica web site: http://www.app.pan.pl/article/item/app20120101.html