Making the skeletons dance
posted May 19th, 2011
Two days ago walking through the hall outside the main Bird Division Offices, I bumped into Nate Smith, a University of Chicago graduate student of Dr. Pete Makovicky, Dr. Julia Clarke (University of Texas), Dr. Dan Ksepka (North Carolina State University), and graduate student Dan Field (Yale University). They were on their way down to our skeleton range essentially to raid it. It is not the first time; it will not be the last, and it is always exciting. Fossil deposits in Wyoming, dating back some 50 million years to the Eocene, where Vice President for Collections and Research Dr. Lance Grande looks for fossil fish each summer are yielding exquisitely preserved fossils of early birds. The preservation can include feathers and even stomach contents. Lance is in the process of writing a new book describing the animal and plant fossils from this area.
For birds, the challenge is to figure out how these early birds are related to modern birds and that is where Julia’s team needs to access our collection of modern bird skeletons. There are few better or more comprehensive collections of bird skeletons in the world, so the paleontologists essentially have one-stop shopping to pull out boxes containing specimens of bird groups such as frigatebirds, rails, sunbitterns, swifts, rollers and mousebirds, because these are the groups of modern birds that appear to share characteristics with the fossils. It is not simple work; it is necessary to do a detailed study of the characters on the fossils compared to modern skeletons, because appearances can be deceiving and just because something looks like a modern bird based on long legs or bill shape, other characteristics of shape or structure may indicate a relationship with another modern group and over fifty million years, a lot of evolutionary change can happen.
This morning, I stopped by the office next to Pete Makovicky’s where for the time being, Juila and Nate and the Dans have pushed aside Pete’s dinosaur fossils (aka really early birds) so they can work with the Wyoming fossils and all the comparative modern material they have brought up from the Bird Division. The photo I took is of Julia and Dan Field discussing the structures displayed in the fossil bird on the table. Is it a rail? Maybe, but until they do a more thorough analysis of all the characters, they consider it an open question. Next to the flat slab containing the fossil are boxes of skeletons from our collection and individually numbered bones of different species are out next to the fossil for comparison.
It is worth thinking about what it took to make this research possible. Funds had to be available to get collectors to the field. The fossil had to be found and recognized as something interesting. Then it had to be removed, brought back to the museum and vary carefully prepared by experts. To assemble this magnificent collection of modern skeletal material, fieldwork around the world was necessary (e.g., South America, Africa, Madagascar) where specimens were collected. These specimens had to be prepared and tagged in the field. Then, they were brought back to Chicago to be processed, meaning they had to be given to the dermestid beetle colony to have all the flesh eaten off. Then they were boxed and the individual bones numbered (so that when a bone is taken out of a box it can be returned to the right box). Some of these specimens are the result of fieldwork done 100 years ago, some are from field work done in the last 20 years. All these steps in both the Geology Department and the Bird Division require a great deal of time, effort, and experience by dedicated staff, but the payoff comes when world class scholars like these can sit together and unravel some of the most interesting issues of how animals have evolved.
Another tie to the Bird Division comes from the paleontologists’ ability to reference Dr. Shannon Hackett (Associate Curator of Birds) and colleagues’ 2008 paper: A phylogenomic study of birds reveals their evolutionary history (Science 320: 1763-1768). Shannon and her colleagues had a National Science Foundation grant to create the largest molecular data set ever gathered on the relationships of all the major lineages of birds. The genetic results, and a comparable morphological study by the late Brad Livezey (Carnegie Museum of Natural History) and colleagues, and fossils like the ones Julia’s group are analyzing provide reciprocal illumination about the timing and evolution of birds in ways that were previously unimaginable. All this work relies on collections.
So keep a look out for Lance’s new book on these wonderful fossils and expect the results of the work that is being done by Julia, the Dans and Nate to shed new light on how we think about the evolutionary history of birds. That is what these great collections allow museum researchers to do.
Feathers are preserved in addition to bones in this fossil, but what is it? On the side are bones from modern birds that are being used by Julia et al. to figure this out.