Presenter(s): Shyla Davison—Earth Science
Faculty Mentor(s): Samantha Hopkins
Session 6: The Earth, Sky & Everything In Between
The Mascall formation of Central Oregon is a rock unit that was formed during the middle Miocene (~15 million years ago) . The Mascall formation was first described from North Central Oregon, but also outcrops to the south in the Crooked River Basin, where it is much older . While these southern outcrops of the Mascall Formation have been known for some time, recent research shows that they are about a million years older than the outcrops of the same formation in the John Day Basin . This particular formation is known for producing many Barstovian-age mammals . Recent collections by University of Oregon field crews have yielded new material from the Crooked River region . I have diagnosed two new specimens recovered from the Mascall formation from Twin Buttes near Paulina, OR, as Monosaulax typicus from the family Castoridae . One specimen is a fragment of a lower right jaw that contains the p4-m2, while the other is a left jaw fragment . These are the most complete remains of M . typicus from the Mascall formation; other known specimens are isolated teeth . The teeth have all the diagnostic characteristic of other previously identified specimens of M . typicus that were found in Southeast Oregon rocks of similar age (Shotwell, 1968) . The information of this new specimen will add to the limited knowledge of this species and the environment of the Crooked River Basin .