Dr. Richard Cifelli ex­plores the evo­lu­tion of early mam­mals in this week’s Speaker Se­ries

The Drumheller Mail - - AROUND TOWN - Sub­mit­ted The Drumheller Mail

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

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