My Research

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Matthew Bonnan from a recent photo.

I am interested in the forelimbs of dinosaurs because they played so many diverse roles from grasping to body support. The common ancestor of all dinosaurs was a biped that used its forelimbs for capturing prey or manipulating food. However, several groups of dinosaurs became quadrupeds, converting the forearm into a foreleg. One quadrupedal group, called the sauropods, became the largest animals ever to walk on land, and a lot of my research has been dedicated to understanding the role of their forelimbs in locomotion, posture, and support before and after they became giants.

To seek the answers to my paleontology questions I have traveled the globe to study dinosaur skeletons in the field and at museums. A highlight of my career has been National Geographic-sponsored field work with an international team of colleagues in South Africa which led to the discovery of three new species of plant-eating dinosaurs closely related to the common ancestor of the giant sauropods. One of these dinosaurs, Aardonyx, was a transitional fossil that shows the beginnings of the switch from bipedal to quadrupedal locomotion.
 
More recently, in the laboratory, my colleagues, students, and I are using using a technique called XROMM (X-ray Reconstruction of Moving Morphology) to non-invasively study how the bones in the forelimbs of living birds, reptiles, and mammals move. We are using these data to test hypotheses about the evolution of forelimb posture in the ancestors of mammals and dinosaurs. I have also dabbled in a few shark studies, including a recent exploration of newborn size and growth in the giant fossil shark Megalodon.

Paleontology

Functional Morphology & XROMM