by Len Lear
Wyndmoor resident Edward B. ‘Ted’ Daeschler said goodbye Sunday to a dear old friend, but the old friend did not shed any tears or even wave goodbye. That’s because the “friend” is 375 million years old.
Daeschler, you see, is a vertebrate paleontologist and Chair of Vertebrate Biology at the Academy of Natural Sciences (of Drexel University) in center city. He is a specialist in fish paleontology, especially in the “Late Devonian” period of history and in the development of the first limbed vertebrates. (The Late Devonian period was about 375 million years ago, when the first forests were taking shape on land, and the first tetrapods — animals with limbs — appear in the fossil record.)
Deaschler, 56, who received a PhD from the University of Pennsylvania in 1998 and is known for his work on the preservation of natural history collections, is the discoverer of the transitional fossil tetrapod Hynerpeton bassetti and a Devonian fish-like specimen of Sauripterus taylorii with fingerlike appendages. He was also part of a team of researchers that discovered the transitional fossil “Tiktaalik,” also known as the “fishapod,” whose bones were on public display from May 2 through last Sunday at the Academy. The exhibit included a touchable cast of the skull, a collection of items including toys that reference Tiktaalik and a video of Daeschler’s appearance on the “Colbert Report” shortly after the discovery was announced in 2006 in the journal Nature.
On Wednesday, May 6, Daeschler recounted his adventures — and hardships — during nine expeditions to Ellesmere Island, Nunavut, north of the Arctic Circle, where his team discovered Tiktaalik roseae and many other fossils. Those nine trips also included ventures to explore Devonian-age formations across a wide swath of the Arctic Islands and into other geologic formations that Daeschler believes may harbor important new discoveries. Last Sunday Daeschler also shared stories of his explorations in the inhospitable terrain of the Arctic.
The discovery by Daeschler and his team shows that the evolution from life in water to life on land happened gradually in fish living in shallow water. For about a century, scientists have been able to trace the broad outline of the millions-of-years-long transition of lobe-finned fish to limbed animals. The new find, however, is the most compelling evidence yet of an animal that was on the verge of the transition from water to land. “The find is a dream come true,” said Daeschler in an earlier interview with the Local. “We knew that the rocks on Ellesmere Island offered a glimpse into the right time period and were formed in the right kinds of environments to provide the potential for finding fossils documenting this important evolutionary transition.”
Tiktaalik was a predator with sharp teeth, a crocodile-like head, and a flattened body that lived in what was then a subtropical climate. The quality of the fossils allowed the team to examine the joint surfaces on many of the fin bones and figure out that shoulder, elbow and wrist joints were capable of supporting the body like limbed animals. “Tiktaalik blurs the boundary between fish and land animals,” said Dr. Neil Shubin of the University of Chicago, another co-leader of the expedition along with the late Farish A. Jenkins, Jr., of Harvard University. “This animal is both fish and tetrapod; we jokingly call it a fishapod.”
Instead of using the traditional Latin or Greek to name the fossil, the team consulted Nunavut residents, who suggested Tiktaalik (tic-TA-lick), the Inuktikuk word for large, shallow water fish. The second part of the name, roseae, honors an anonymous supporter. Other funding came from the National Science Foundation, National Geographic Society and the researchers’ home institutions.
The expedition uncovered the fossils in 2004 in a remote valley of Ellesmere Island, more than 600 miles north of the Arctic Circle, in Canada’s Nunavut Territory. It was the fourth summer they had spent there amassing a diverse array of fossil fish dating to the Late Devonian period. Tantalizing fragments uncovered in 2000 convinced the scientists to return to the site. Scientists do not now know why Tiktaalik developed the body type that allowed it to come out of the water.
Later this month Daeschler and Shubin will drive the bones of the Tiktaalik to the Canadian Museum of Nature in Ottawa, Ontario, along with many other fossils they found in the Canadian Arctic. The return of the fossils was a pre-condition of an agreement with Canadian officials that permitted the Philadelphia scientists to excavate in the first place.
Daeschler told us in an earlier interview that most people don’t recognize the Academy of Natural Sciences, which is more than 200 years old, as the world-class institution that it is. Since it is one of the top 10 natural science museums and research centers in the country, scientists from all over the world come to Philadelphia to work with the Academy’s collections and use its library. “It’s an unknown treasure,” said Daeschler. It is the oldest natural history museum in the county and houses the largest collection of specimens.