Dr. Richard Cifelli explores the evolution of early mammals in this week’s Speaker Series
The February 25 session of the 2016 Royal Tyrrell Museum’s Speaker Series is a presentation by Dr. Richard Cifelli from the University of Oklahoma entitled “Early Cretaceous Mammals from the Cloverly Formation, Montana.”
The Early Cretaceous (about 100 to 140 million years ago) is an interesting interval in the history of mammals. During this time, a variety of archaic and now largely extinct kinds of mammals co-existed with a newly evolved group of mammals called “therians.” Two groups of therians (marsupials and placentals) arose and began diversifying during the latter part of the Early Cretaceous, and went on to become the dominate kinds of mammals on our planet. Most early mammals were small, and their delicate bones do not often preserve well as fossils. Much of the record for early mammals, especially from North America, consists of isolated fossil teeth and broken jaws. Fortunately, mammal teeth contain a wealth of features that are useful for understanding the lifestyles and evolutionary history of fossil mammals.
In his presentation, Dr. Cifelli will talk about new insights into Early Cretaceous mammals resulting from his ongoing fieldwork in the Cloverly Formation (about 110 million years old) in southern Montana, USA. One unusually productive site, which is a pocket of rock only about the size of a bread loaf, is packed with bones and teeth of early mammals and other animals. These fossils are hard to find and recover, so his team is using a combination of mechanical preparation and high-resolution CT imaging to study the fossils. One of the most exciting specimens is a set of jaws from a previously unknown kind of early therian mammal. The jaws have a mixture of both milk and adult teeth, indicating that the animal died as a juvenile. Other important fossils from the site include a symmetrodont (an extinct mammal group) and many lizards. Why these tiny fossils accumulated in such a localized spot remains a mystery. One possibility is that the deposit may represent an accumulation of bones from a carnivore feeding on small animals.
The Royal Tyrrell Museum’s Speaker Series talks are free and open to the public. The series is held every Thursday until April 28, 2016 at 11:00 a.m. in the Museum auditorium. Past presentations are also available on the Museum’s YouTube channel: youtube. com/ user/ RoyalTyrrellMuseum. For more information, visit tyrrellmuseum.com.
Dr. Richard Cifelli… presenting at Speaker Series