Ph.D. Biology 2019 University of Washington
Vertebrate paleontology and paleohistology
Our research examines the microscopic structures preserved in fossil bones and teeth to bring animals that have been extinct for hundreds of millions or years to life. Our lab looks at a range of animals that lived at different critical transitional moments in vertebrate evolution. There are several major research areas that are active in our lab:
1. The evolution of the mammalian dentition. The mammal dentition (e.g. prismatic enamel, complex tooth shape, single tooth replacement) is considered a hallmark of our evolutionary history. Yet, the story of how and when this dentition arose has not previously considered the entire 300 million years of evolution of our synapsid lineage. I research non-mammalian synapsids to find out when these traits first appeared if there are correlations between traits, and if there are instances of convergent evolution that can tell us something about the selective pressures that gave rise to the mammalian dentition.
2. Seasonality in the Triassic of Antarctica. Antarctica has not always been the ice and snow-covered continent it is today. In fact, during most of the history of life on Earth, it has been home to a variety of different plants and animals. Despite its warmer climates, the continent has remained in the polar circle and the life living there would have experienced extreme light and dark seasonality. We are interested in looking at any physiological adaptations of the animals that lived in this polar environment during the Triassic.
3. The diversification of terrestrial tetrapods. One of the most consequential transitions in vertebrate evolution was the transition from water-dwelling to land-dwelling tetrapods. We are currently using bone histology to better understand the life histories and biologies of early tetrapods from the Carboniferous (between 360 -390 million years ago). In revealing aspects of these animals' biology, we hope to shed light on how vertebrate life diversified on land.
4. Pathologies in the fossil record. The nature of paleohistological work has led to a collection of specimens that had pathologies. We are interested in providing an evolutionary context for disease and pathology as well as exploring any insights these pathologies can provide about the biology of fossil vertebrates. This work includes a tumor in a 255 million-year-old gorgonopsian (saber-toothed mammal relative) and trauma to the ever-growing tusks of several dicynodont mammal-like relatives.
Whitney, M. R., K. D. Angielczyk, B. R. Peecook, and C. A. Sidor. The evolution of the synapsid tusk: insights from dicynodont therapsid tusk histology. Proceedings of the Royal Society B 288:20211670.
Whitney, M. R. and S. E. Pierce. Osteohistology of Greererpeton provides insight into the life history of an early Carboniferous tetrapod. Journal of Anatomy DOI: 10.1111/joa.13520.
Whitney, M. R., A. R. H. LeBlanc, A. R. Reynolds, and K. S. Brink. Convergent dental adaptions in the serrations of hypercarnivorous synapsids and dinosaurs. Biology Letters 16(12):20200750.
Whitney, M. R. and C. A. Sidor. Evidence of torpor in the tusks of Lystrosaurus from the Early Triassic of Antarctica. Communications Biology 3:471.
Whitney, M. R. and C. A. Sidor. Histological and developmental insights into the herbivorous dentition of tapioncephalid therapsids. PLoS ONE 14(10):e0223860.
Whitney, M. R., L. Mose, C. A. Sidor. Odontoma in a 255-Million-Year-Old Mammalian Forerunner. JAMA Oncology 3(7):998—1000.
Curry Rogers, K. A., M. Whitney, M. D’Emic and B. Bagley. Precocity in a tiny titanosaur from the Cretaceous of Madagascar. Science 352(6284):450-453.