You are what you eat: using dietary trace elements to examine the life histories of dinosaurs and other fossils
David Terrill, PhD Candidate, Department of Geoscience, University of Calgary
LOCATION: Mount Royal University, Room B108
TIME: May 10, 2019, 7:30 pm
When considering the nature of paleontological remains, the first images that come to mind are usually that of preserved skeletons, which can include vertebrate bones, the exoskeletons of arthropods such as trilobites, the hard shells of molluscs and brachiopods, the calcitic skeletons of corals, and many others. These hard tissues often form the basis of our understanding of life in the distant past, as we use them (sometimes with the help of exceptionally preserved soft tissues like skin and feathers) to reconstruct the animals from which they came. We then combine this with information obtained from the rock record such as fossil tracks and traces, pollen, and geological information to help us understand what the environment was like and how these animals may have lived during that time.
One, often, overlooked source of information that has been gaining traction in the last two decades is chemical data. While the process of fossilization often replaces original biological tissues with other minerals, certain fossils retain at least a small portion of their original composition. Of all the fossils known, perhaps the best source of original biological materials is the enamel of vertebrate teeth. Enamel is incredibly hard and resistant, to the point where it is virtually unchanged in fossils dating several hundred million years. The primary components of enamel include elements such as phosphorous, calcium, carbon, and oxygen, however a number of other elements can be found in trace amounts.
For my work, I primarily focus on strontium, a substitution element for calcium in bones and teeth. Similar to calcium, strontium in the body primarily comes from dietary sources. This means the isotopes of strontium and overall abundances preserved in fossil enamel reflect the diet of the animal. As strontium in the environment is strongly linked to the eroding bedrock in a given area, the isotopes preserved in the enamel can be linked through the animal’s diet back to the location where the animal had been feeding. Using this property of strontium, I have attempted to reconstruct the migratory behaviours of hadrosaurs from the Late Cretaceous of Alberta. The relative abundance of strontium preserved in the enamel can also be used to estimate where approximately an animal may fit in the foodchain. I have applied this to a separate project on Silurian conodonts, which are small eel-like fish fossils. Though well-studied, little is known about the ecology of these animals; through strontium analysis, I hope to be able to show how different conodont species may have exploited different types of food sources. Finally, I will present a few ideas for future paleontological studies using similar techniques.
Growing up in Calgary, David had many opportunities to visit the Royal Tyrrell Museum in Drumheller and was an avid fan of dinosaurs growing up. After beginning a BSc. In astrophysics at the University of Calgary, David picked up a summer job working at the museum, where he rekindled his fascination with all things paleontological. A few summers later, David began leading hikes to the Burgess Shale fossil beds in the Field BC area. He graduated in 2010 with undergraduate degrees in astrophysics and geology.
From 2010 to 2017, David worked seasonally as a parks interpreter at Dinosaur Provincial Park, where he had many opportunities to join scientists from the Tyrrell museum and University of Alberta on field excursions in and around the park. He completed an MSc. in 2015 studying sulfur preservation in conodonts, attempting to clarify the relationship of the mysterious group of fossils as they relate to other vertebrates. Currently David is a PhD candidate at the University of Calgary studying dinosaur migration and conodont ecology, and will once again be guiding hikes to the Burgess Shale this coming summer.