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Fortieth George Gamow Memorial Lecture

Paul C. Sereno
Paleontologist
Department of Organismal Biology
University of Chicago

"Dinosaurs on Drifting Continents"

 

The Mesozoic Era witnessed the pulling apart of a supercontinent and the simultaneous rise and fall of dinosaurs, the first group of land animals to achieve and maintain a global distribution.  Their history is recorded by abundant fossils on all continents. 

The central focus of my research has been to chart the evolution of dinosaurs and reveal how a fragmenting geography influenced their evolution.  How does the breakup of a supercontinent affect land-based life?  Does diversity or the pace of evolutionary change increase?  Does phylogeny track geography? How do novel and demanding functional capabilities, like powered flight, first evolve?  What triggers or drives major replacements in the history of life?  Questions like these are answered primarily, or entirely, with evidence from the fossil record.  The study of long-term, large-scale paleontological patterns is an important component of current evolutionary research.

Research has taken me to collections around the world in dogged pursuit of the skeletal details that allow us to stitch together, with efficient computer algorithms, the tree of dinosaur life.  Fieldwork, in turn, has focused on Cretaceous rocks (66 to 144 million years old) on the little explored southern continents, in an attempt to shed light on their isolated faunas. 

Beginning in 1988 in the foothills of the Andes in Argentina, my team discovered the first dinosaurs to roam the Earth, the predators Herrerasaurus and the most primitive of all, Eoraptor, the "dawn raptor." In the early 1990's we shifted our focus to Africa's lost world of dinosaurs. Discovering them has involved a series of intrepid expeditions into the heart of the Sahara, where we discovered and named Afrovenator, a new 27-foot-long meat-eater, and skeletons of a 70-foot-long plant-eater named Jobaria. We discovered a bizarre fish-eating dinosaur, Suchomimus, with huge claws and a sail on its back, and another 45-foot-long plant-eater we named Nigersaurus. In Morocco we unearthed the most fleet-footed meat-eater, the 30-foot-long Deltadromeus, and the skull of a huge, T. rex-sized meat-eater Carcharodontosaurus. Besides new and unusual dinosaurs, we stumbled on the world's largest crocodile, the 40-foot-long Sarcosuchus, dubbed SuperCroc. Most recently, we announced the first predator from India, Rajasaurus, and a new meat-eater from Africa, Rugops.

Dinosaur evolution, it turns out, was influenced by global geographical events and shaped indelibly by the fickle hand of extinction. The result is a spell-binding tale of evolution on island continents that is no more predictable than that of a well-planned paleontological expedition. Speaking of which, my next will be to the last totally unexplored piece of the great southern landmass Gondwana—better known as Tibet.

Paul Sereno grew up in Naperville, a suburb of Chicago, and studied art and biology as an undergraduate at Northern Illinois University. He earned a doctorate in geology at Columbia University and the American Museum of Natural History in New York. In 1987, he joined the faculty of the University of Chicago, where he teaches paleontology and evolution to graduate and undergraduate students and human anatomy to medical students. He is the co-founder, with his wife Gabrielle Lyon, of Project Exploration, a nonprofit science education organization, and an Explorer-in-Residence with the National Geographic Society.