November 16, 2009
A new family of ancient clams has been discovered in Israel's Negev Desert by a team of scientists that includes College of Wooster Professor of Geology Mark Wilson.
WOOSTER, Ohio - A strange-looking new family of ancient clams has been discovered in Israel's Negev Desert by a team of scientists that includes a professor and a recent graduate from The College of Wooster.
The odd fossil from the middle Triassic (some 240 million years old) is unlike anything we would recognize as a clam today, according to Mark Wilson, the Lewis M. and Marian Senter Nixon Professor of Natural Sciences at Wooster. "They were unique in that they lived upside down," said Wilson, one
of three authors of a paper that is published in the latest edition of the journal Palaeontology. "They had thick shells, a flat bottom, and a very distinctive top that looked something like a shark's fin."
The significance of the discovery is not only that it represents a new family, but also that its origin came at a critical time in the history of life. "This family emerged after the greatest mass extinction of life on earth - the end of the Permian Period," said Wilson, who worked with lead author Thomas Yancey of Texas A&M and recent College of Wooster graduate Allison Mione on the project. "Many unusual organisms developed then as life diversified."
The findings by Wilson and his colleagues resulted from three years of research in Israel. "We had many fragments of the fossil, but we needed to find whole specimens," said Wilson. "We eventually found a particular place where the rock was folded and faulted just right to yield complete fossils."
The researchers gathered a dozen specimens, ranging in age from juvenile to adult, and turned them over to Yancey, an expert on fossil clams, to put them into context. They concluded that this was, indeed, a new family because of its uncommon characteristics. For example, Yancey noted that the two halves of the shell, which pointed upward, actually came apart at the hinge and grew
independently of one another, thus preventing the clam from completely closing. The team of scientists believes that the clam lived on the surface and was often partially covered by sediment, leading to the development of reef-like mounds. The trio also deduced that the tissue, or mantle, inside the clam was probably extended outside the shell to facilitate a process known as
photosynthetic symbiosis in which other organisms (such as algae) that lived in the tissue could produce nutrients and oxygen. "It's known as mutualism," said Wilson. "Two organisms live together and both benefit."
Ironically, this family of clams had been discovered more than a half-century ago, but the
scientists misidentified it, according to Wilson. "It is not a pretty fossil group, but it is a very interesting one," he said, adding that the experience led to several valuable lessons. "Many people think that the fossil records are complete and that there is nothing new to be added," he
said. "This shows that there is still much we don't know."
Had the scientists discovered a new family of dinosaurs as opposed to clams, they would have made national news, but the discovery of a new family of clams is still significant, according to Wilson. "This family was part of a fascinating evolutionary process following the mass extinction," he said. "It was part of the recovery fauna that began to repopulate the earth."
Wilson, one of the few foreign geologists who conducts field research in Israel and brings students, says the region is rich in clues about the history of life. "There's much to discover in the diverse geology of Israel," he said, "and fieldwork there is safe and productive."
Wilson also emphasized the important role of undergraduate research in this project. "Allison was an essential member of our team," said Wilson. "She examined these clams and the rocks they were found in to interpret their ancient environment for her geology Senior I.S. project (Wooster's nationally acclaimed undergraduate research endeavor, which matches each student with a faculty mentor in pursuit of a particular topic that culminates in a thesis, performance, or exhibition of artwork). "Few undergraduates have the opportunity to conduct research that leads to the description of a new family."
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