My work was recently cited in a few different articles. For those of you interested in mylagaulid systematics (There might be some), Dr. William Korth just published the mylagaulid fauna from the Barstovian of New Mexico. He cited my work with Dr. Samantha Hopkins on Alphagaulus pristinus and the mylagaulids from the Great Basin.
Dr. Susumu Tomiya published his research on the link between body size and extinction probability (or lack thereof). He cited my article with Drs. Samantha Hopkins and Edward Davis on burrowing rodents diversity through time in the northern Great Basin. That same article was cited last year by Jardine et al. in their study of hypsodonty in small mammals.
Dr. Edward Davis and Brianna McHorse just published an article on multivariate discriminant function analysis of camelid astragali and cited the work of Dr. Davis and I on antelope astragali.
I just came back from NE Montana where I had the opportunity to help out Dr. Gregory Wilson, Lauren DeBey, and their crew for the 2013 Discoveries in Geosciences (DIG) field school. This year’s was the biggest ever with 20 teachers from Oregon, Washington, and Montana. The 4 day workshop was a success. The teachers will be able to go back to their classrooms ready to share great stories, new experiences, and content from the DIG box.
You can learn more about the DIG field school on their page on the Burke website, their website, by reading this article by Winifred Kehl, or by following them on Facebook.
As part of my dissertation, I am interested in studying the biogeographic relationships between Arikareean deposits in the northern United States (Oregon, Montana, Nebraska, Wyoming, and South Dakota). As part of a statistics class at the University of Washington, I have started investigating taxonomic similarities across Arikareean faunas using (in part) ordination methods.
These initial results are published in an in-house journal:
Calede, J. 2012. Biogeography and endemism in Arikareean faunas (North America, 30-18.8 Ma). Electronic Journal of Applied Multivariate Statistics 4:12–22.
You can read the abstract below:
The rich and geographically widespread Arikareean fossil record (North America, 30 to 18.8 Ma) provides a unique opportunity to test hypothesis of geographic clusters and gradients in faunal composition. I use multivariate statistics (cluster analysis and ordinations) to test the hypotheses that early modern mammalian faunas of the Arikareean were significantly different across biogeographic regions, were arranged along geographic gradients and that this apparent biogeographic pattern cannot be accounted for by the incomplete nature of the fossil record. The results show that there is support for a biogeographic structure of Arikareean communities with some possibly endemic assemblages (Cabbage Patch Beds of western Montana, Delaho Formation of southwestern Texas). The fossil assemblages reflect a strong longitudinal gradient. No evidence for a latitudinal gradient is found. Neither age nor sampling seem to influence the observed pattern which instead is correlated with depositional environment. This suggests that much of the observed faunal differences across assemblages and regions can be explained by habitats constraining local and regional faunas. Further study exploring the functional diversity of these assemblages will further investigate the controls on community assembly during the late Oligocene-earlyMiocene.
The Cabbage Patch beds of western Montana span roughly 6.5 million years from about 29. 5 to 23 million years ago crossing the boundary between the Oligocene and the Miocene. This series of fossil-bearing horizons is located in Powell, Granite, Silver Bow, and Deer Lodge counties (Montana). The Cabbage Patch beds house a rich vertebrate (mostly mammals) and invertebrate (mostly land and freshwater snails) fauna as well as floral remains (mostly in the form of phytoliths). These beds have mostly been studied by Dr. Donald Rasmussen in the 1960s and 1970s.
I am continuing Dr. Rasmussen’s work with the goal of comparing the fauna from Cabbage Patch to faunas of the same age located in Oregon (John Day Formation) and Nebraska (Arikaree Group). I am collecting additional fossils and geological data from the field and further analyzing the fossils collected by Dr. Rasmussen housed at the University of Montana and the University of Kansas (mostly).
The goals of my dissertation are to better understand:
Collaborators at the University of Washington and the University of Michigan are investigating these deposits using isotopes and phytoliths to better understand the environment at the time in Montana. You can read more about their research here.
Photo by Andrew Waits, courtesy of The Burke Museum
Members of the Burke Museum recently had the chance to tour the museum collections, talk to researchers, and see fossils usually kept inside the cabinets in the basement. Behind the scenes is an annual event of the Burke.
I was there showing off some Oligo-Miocene mammals from the Cabbage Patch beds of Montana and the John Day Formation of Oregon.
I am currently describing the first snout of Didelphodon vorax. This is part of a larger project on the morphology, phylogenetic affinities, and paleoecology of Didelphodon undertaken by my advisor, Dr. Gregory Wilson. Dr. Wilson and collaborators presented preliminary results of this project at the annual meeting of the Society of Vertebrate Paleontology in 2012.
I am currently pursuing a project on the diet of Cretaceous and Paleocene mammals using microwear analysis. This is part of a larger project undertaken by my advisor, Dr. Gregory Wilson investigating dietary changes across the K-Pg boundary. It complements an investigation of diet across the K-Pg using Orientation Patch Counts (see Evans et al. 2007, Wilson et al. 2012).We presented some preliminary results at the Annual Meeting of the Society of Vertebrate Paleontology in November 2011.
- Microwear in burrowing rodents (jonathancalede.wordpress.com)
I have been working in the Cabbage Patch beds (part of the Renova Formation) of western Montana since 2011. I am collecting additional fossils and geological information building up on the work of Dr. Donald Rasmussen (and others) 40 years ago. This area is very interesting because it will allow me to compare faunas of the same age (about 30 to 20 million years old) across a longitudinal gradient from Oregon to Nebraska through Montana at the time of the spread of grasslands.
You can read a summary of the 2012 field season supported by Sigma-Xi and the Burke Museum‘s division of vertebrate paleontology here. You can also read a summary of the 2012 field season from collaborating paleobotanists here.
I did an additional month of fieldwork this past summer thanks to support from the Tobacco Root Geological Society and the American Philosophical Society. We were once more very successful. With the help of undergraduate assistants and collaborators, I collected sedimentological information to study the taphonomy of the beds and collected some exciting new fossils including a mostly complete carnivore jaw and several rodent jaws (beavers, mice, gophers, and aplodontids). Stay tuned!
Photo courtesy of Judy Carlson
The carnivore fauna from Cabbage Patch currently include a single specimen, a dog named Cynodesmus thooides. My crew and I recently came upon another 15+ specimens while doing field and collection work. I am currently working on the description of this previously unrecognized diversity of carnivorans with an undergraduate student. This is part of a larger project investigating the taxonomic affinities of the Cabbage Patch fauna with the faunas from the Great Plains (Arikaree Group) and Oregon (John Day Formation).
We have already identified 2 more species of dogs, expanded the local stratigraphic range of C. thooides, and found some fossil mustelids (weasels, badgers, wolverines, and their relatives).
I am working with Jenny Glusman, a former undergraduate in Biology at the University of Washington, on the systematics of entoptychine gophers from Cabbage Patch. We are studying the shape of the last upper molar (and other diagnostic teeth) of this group of fossil gophers abundant in the Cabbage Patch beds and the John Day Formation using geometric morphometrics. We are specifically investigating how well the shape of the diagnostic cheek teeth can help differentiate fossil entoptychine taxa. We are using modern geomyine gopher species to validate our approach. The end goal is to be able to determine the geographic and temporal range of entoptychine gophers in the northern United States around the Oligo-Miocene boundary.
Preliminary results of this work were presented at the Annual Meeting of the Society for Cenozoic Research and recently at the Annual Meeting of the Society of Vertebrate Paleontology.
- Great Basin Mylagaulidae (jonathancalede.wordpress.com)