An international research team, including Carleton University’s Michael Ryan, has identified a new species of horned dinosaur based on fossils originally discovered in the 1930s in Southwestern Canada. The small cousin of the larger Triceratops sheds light on the evolutionary development and dispersion of ceratopsians, the group of herbivorous dinosaurs characterized by their horned faces and frills.
A Pint-Sized Ceratopsian
A primitive ceratopsian, called Sasayamagnomus saegusai, lived in stark contrast to its larger and more well-known cousins. Sasayamagnomus would have stood 80 cm tall and weigh only about 10 kg, a stark contrast to the giant Triceratops.
The strikingly small size shows how different the ceratopsian family could be. Sasayamagnomus has given us a valuable perspective on early ceratopsian growth as a young, developing animal. Its incomplete internal bone structure and growth rings indicated that it was not yet fully-grown when it died, which helps provide a detailed look at the life cycle of these animals and their intricate growth patterns.
Connecting Two Worlds: The Ceratopsian Connection Between Asia And North America
The new species helps clarify the zany tale of ceratopsian migration. The new dinosaur is closely related to primitive ceratopsians of North America, suggesting that these plant-eating giants may have traveled from Asia to what would become North America around 110 million years ago, during the mid-Cretaceous time.
Additionally, the eastern portions of both North America and Asia were connected through Beringia at about this time allowing for the migration of fauna between the two regions. Moreover, the warm temperatures during this time frame allowed for extensive forests to grow in the Arctic — environments where ceratopsians could potentially spread into by exploiting a land bridge.
This migration pattern not only shows the flexibility of ceratopsians, but also emphasizes how critical geological and climatic events are to shaping the distribution and evolution of prehistoric life. The discovery of Sasayamagnomus, helps unravel the connections between Asia and North America, shedding new light on the complex biogeographic history of these iconic dinosaurs.
Conclusion
Sasayamagnomus saegusai, a ceratopsian whose diminutive size was a lucky and perhaps deceptive result of isolation on an island in Japan, offers us information neither of those more familiar “stagosaurs” could; it speaks about the full range of diversity this group once had as well as some very specific ideas about how at least one lineage made its way from western North America to eastern Asia. The discoveries of this pocket-sized dinosaur thus add not only to the plethora of form that we now know were present in the ceratopsian family, but also broadens our understanding as to how and why these well-known herbivores may have spread across the ancient lands, untouched by time. There should be even more exciting findings in the future as researchers continue to investigate this extraordinary fossil and allow us a glimpse further into the lives of these incredible Earth Wandering giants.
