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The insatiable curiosity of the scientists at the Royal Tyrrell Museum drives the research program, and their discoveries provide the basis for everything we do—from educational programming to exhibit development. Their work enhances our understanding of the evolution of life on Earth. Here is some of their current research.
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Ancient cool-water shark shifted its geographic distribution with climate change
A team of researchers has discovered teeth of a 94-million-year-old, large (6 m) shark called Cardabiodon ricki in Alberta, Canada. This species was previously only known from Australia and Europe. Closely related species have also been found in Australia and the USA. In the past, researchers have suggested that these sharks had an antitropical distribution, meaning they only occurred in cool climates at high latitudes and not in the warmer tropics. A modern analogy is the Porbeagle shark, which also has an antitropical distribution—it is restricted to cooler regions between 30º and 60° latitude, where sea surface temperatures range from 5 to 10°C.
The team designed a new three-part test for the idea that Cardabiodon had an antitropical distribution by looking at the occurrences of these shark fossils from around world and using data on ancient climates published by other geoscientists. They compared the range of sea surface temperatures and palaeolatitudes for fossil finds of Cardabiodon to those of the Porbeagle shark, hypothesizing that the habitats of the ancient and modern sharks should exhibit similar ranges of temperature and latitude. They also hypothesized that the distribution of the fossil sharks should shift as climate changed over millions of years.
Cardabiodon had an antitropical distribution because it was found in colder sea surface temperatures within a narrow range, its geographic distribution was from higher latitudes, and because the distribution of Cardabiodon shifts with climate change. The team found that sea surface temperatures for the fossil shark varied only slightly more than those for the modern Porbeagle (1.7º more), and that the fossil shark inhabited a narrower range of latitudes (10º latitude less) than the modern shark. They also found that the fossil shark shifted its distribution as climate changed, being found closer to the poles during warm periods in both hemispheres, but closer to the equator during cooler periods of Earth’s history. Ancient sharks thus tracked climate change, which suggests that modern sharks may also track with modern climate change. This inference is important as we know nothing about how modern sharks will respond to climate change.
Cook, T.D., M.V.H. Wilson and M.G. Newbrey. 2010. The first record of the large Cretaceous lamniform shark, Cardabiodon ricki, from North America and a new empirical test for its presumed antitropical distribution. Journal of Vertebrate Paleontology 30:643 649.
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