Molecular Phylogenetics of Mastodon and Tyrannosaurus rex
Chris L. Organ,1,2
Mary H. Schweitzer,3,4
Wenxia Zheng,3
Lisa M. Freimark,5
Lewis C. Cantley,5,6
John M. Asara5,6*
We report a molecular phylogeny for a nonavian dinosaur, extending our knowledge of trait evolution within nonavian dinosaurs into the macromolecular level of biological organization. Fragments of collagen 
1(I) and 2(I) proteins extracted from fossil bones of Tyrannosaurus rex and Mammut americanum (mastodon) were analyzed with a variety of phylogenetic methods. Despite missing sequence data, the mastodon groups with elephant and the T. rex groups with birds, consistent with predictions based on genetic and morphological data for mastodon and on morphological data for T. rex. Our findings suggest that molecular data from long-extinct organisms may have the potential for resolving relationships at critical areas in the vertebrate evolutionary tree that have, so far, been phylogenetically intractable.
1 Harvard University, Cambridge, MA 02138, USA.
2 Museum of Comparative Zoology, Cambridge, MA 02138, USA.
3 North Carolina State University, Raleigh, NC 27695, USA.
4 North Carolina Museum of Natural Sciences, Raleigh, NC 27601, USA.
5 Beth Israel Deaconess Medical Center, Boston, MA 02115, USA.
6 Harvard Medical School, Boston, MA 02115, USA.
* To whom correspondence should be addressed. E-mail: jasara{at}bidmc.harvard.edu
