Reproduction in Troodon Formosus

America's First Dinosaur

3/20    Reproduction in Troodon formosus, America’s First Dinosaur. Presented by David Varricchio, Montana State University.

The term “dinosaur” was first coined in 1842 by Richard Owen, and the world was amazed by early large dinosaur fossils. Charles Darwin’s “On the Origin of Species”, published in 1859, thrust the role of evolution and the changes in life on earth through deep time into public awareness. But by the early 20th century vertebrate paleontology and dinosaurs were rather stagnant fields  –  what more could be learned from dry bones? But this changed dramatically with new scientific tools and especially new scientific ideas. Arguments about dinosaurs being warm blooded, being feathered, being caring parents, began to rage in the late 20th century. And the realization that birds are almost certainly extant dinosaurs came to be generally accepted as well.

Dr. David Varricchio has studied and published on dinosaurs for a quarter century, and has been involved in the development of cutting edge ideas & research. During his talk he will discuss how we are now able to begin to understand dinosaur behavior and links with modern birds from work that he and colleagues have conducted.

From the Two Medicine Formation of Montana, USA, Troodon formosus, “beautiful wounding tooth”, was a small (~ 50kg) carnivorous dinosaur sharing a close ancestry with birds.  An excellent fossil sample including eggs, embryos, clutches, a nesting trace and a clutch-associated adult, provides exceptional insight into the reproductive behavior of this dinosaur. Troodon reproduction represents a combination of some primitive features found in modern reptiles (two reproductive tracts, buried eggs, precocial young), many features shared with birds (smooth, large, and asymmetric eggs, three structural layers, low porosity, iterative egg production, brooding), and some unique aspects peculiar to Troodon (elongate eggs, half-buried eggs, eggs upright with the sediment).  While many reproductive features of modern birds clearly had their origin within dinosaurs like Troodon, most dinosaurs, lacked these features, and likely exhibited very different reproductive behaviors. Finally, the fossil evidence is strong enough to suggest the type of parental care in Troodon, the length of incubation, and possibly even the mating system used.