Neil Shubin says that he was introduced to his inner fish when he first moved to the University of Chicago to serve as chair of the anatomy department.
One of the pivotal courses for medical students is the human anatomy course.
“Within weeks, it became clear that being a paleontologist, and not just any paleontologist, a fish paleontologist, is a powerful way to teach human anatomy. Why? Because often the best roadmaps to our own bodies lie in the bodies and embryos and DNA of other creatures.”
Shubin says ancient fossils can tell us about our deep history, a history shared with flies, worms and fish. Part of his own introduction to the shared world happened as a student in a graduate seminar.
In 1987 there was a gap in the fossil record in the fish to amphibian transition. There were lobed fish in fossils that are 390 million years old, meanwhile there is an amphibious four-footed creature that is about 365 million years old.
“This struck me as a wonderful scientific problem to study,” says Shubin.
“You have this giant evolutionary leap from life in water to life on land involving changes in physiology, ecology, anatomical structure to development and it struck me by looking at this that this is a problem that is knowable. That by finding new fossils, by studying living animals in certain ways we can begin to bridge this gap in understanding on how it happened.”
What he was looking for was something between fish and a limbed animal.
Ancient fish have a conical head with eyes on either side, no neck, gills and fins. Ancient limbed animals have flatter – similar to a crocodile – shaped heads, and their eyes are on top. Early limbed animals also have a neck that allows the head to swivel independently of the body and jointed legs.
Shubin had a plan to find sedimentary rocks of around 380 million years old. His first attempt in the 1990s centered on the Catskills of Pennsylvania since there was an abundance of Devonian era rock.
While he was able to reconstruct the ancient ecosystem of the area, which was filled with large limbed predatory creatures and smaller species through the various fossils he found, he was unable to find the sought-for transition animal.
He realized he needed to find sedimentary rocks that predated the Catskills by 15-20 million years. He found what he was looking for by accident when he looked into an old textbook and found that Ellesmere Island was relatively unexplored.
Five years later they found a fossil of a flat-headed fish which turned out to be a blend of fish and amphibian. This creature had four jointed ,weight-bearing fins, a neck, both gills and lungs and a flattened head with the eyes on top. A committee of Nunavut elders named the creature Tiktaalik.
This transition fish showed that once the structures of jointed four limbs and neck appeared they spread throughout the tree of life and can be seen in reptiles, birds, mammals and, of course, amphibians.
Since Shubin’s talk at Western was a blend of geology, biology, paleontology and evolutionary theory it was a great opportunity for the departments of Biology and Earth Sciences to present the event as the SCUGOG-Battle Lecture.
Earth Science Chair Gerhard Pratt initiated the idea, then Biology Chair Mark Bernards became involved as well as each department’s undergrad societies and seminar committees. Each department allocated money from seminar budgets, and the two undergrad societies contributed from discretionary funds.
Each year, Earth Sciences and Chemistry sponsor the SCUGOG Lecture, featuring a world-renowned scientist on an Earth Sciences topic. An anonymous benefactor funds the SCUGOG Lecture with the goal of providing a high quality lecture to the public by an eminent earth scientist.
The Helen Battle lecture series is presented in memory of Helen Battle who had a long and highly-distinguished career at Western.
Tiktaalik (nickname ‘fishapod’)
What is it: A species of fish dated at 375 million years old found in 2004 on Ellesmere Island in the Canadian Arctic. The fish dates from a time when Ellesmere was located near the equator in a tropical environment.
What does the word mean: This is an Inuktitut word referring to a cod-kike fish called burbot.
Claim to fame: Lived at the time when the first fish appeared on land. Appears to be a transitional creature, with features resembling fish and early four-legged land animals called tetrapods, hence ‘fishapod.’
“It is a fish that blurs the distinction between a fish and a land-living animal,” says co-discoverer Neil Subin.
Learn more about Tiktaalik from a Q&A, see dig videos from Shubin’s headcam and drawings at https://tiktaalik.uchicago.edu/
Source: University of Chicago