My research centers on exploring the macroevolutionary patterns and processes of biodiversity and morphological disparity, including how species diversify in the functional, phylogenetic, and developmental constraints of convergent evolution within an explicitly evolutionary framework. I have interests in comparative anatomy, osteology, biostratigraphy and biochronology, and macroevolution. I investigate how a cladistic framework modifies our secondary inferences, such as the use of fossil vertebrates for biochronology or our understanding of paleobiogeographic patterns, and explore the acquisition of the ‘modern’ fauna through extinction and diversification events. My primary objectives are to explore the anatomical evolution of reptiles, which are often poorly-understood components of well-sampled terrestrial assemblages. In addition, I investigate changes in their ecology and diversity. I incorporate critical data from fossil specimens with my research on extant taxa, using CT and traditional dissection, through my fieldwork (domestic and international), which enables me to explore the regional and chronologic differences between and among terrestrial vertebrate assemblages and continental ecosystems over deep time.
Ph.D., Geological Sciences, The University of Texas at Austin, 2013
MSc., Geosciences, University of Iowa, 2008
B.S., Geological Sciences, University of Michigan, 2003
I have three primary areas of research currently.
- Paleobiology and Evolution of Phytosaurs and other Triassic Archosauromorphs: Phytosaurs are a clade of semi-aquatic reptiles that look superficially like crocodylians and would have been some of the dominant predators in the Late Triassic. They currently are known only from Late Triassic fossils, but they have a hypothesized ghost lineage extending from the Early Triassic. They had a nearly worldwide distribution, and therefore they have been utilized for over 100 years for biostratigraphic and biochronologic correlations. I investigate the morphological evolution of this clade, test hypotheses of phylogenetic relationships, and explore functional abilities of the group.
- Evolution of Paleogene Reptiles: Squamates (lizards, snakes, and amphisbaenians) and crocodylians are well-known from the Western Interior during the Eocene, but until recently southern records were unclear. I work to uncover the poorly-known reptile components of the Eocene faunas of West Texas and understand their connections to taxa from Wyoming and Utah with respect to the climatic upheaval and associated faunal changes that occurred early in the Cenozoic.
- Evolution and Biogeographic History of Amphisbaenians and Fossorial Vertebrates: Fossoriality, or a burrowing lifestyle, evolved multiple times among vertebrates and appears to be associated with certain morphological adaptations. I focus specifically on the evolution of amphisbaenians, a group of limbless squamates, that are known today from a world-wide distribution and have a North American fossil record back at least to the Paleocene. I specifically am interested in the evolution and biogeographic history of rhineurid amphisbaenians, a clade which contains one living member, the Florida worm lizard.
We are part of the larger, very active Paleobiology & Geobiology Research Group here at Virginia Tech.
To learn more, please visit our main research page here:
- Krista Koeller (MS program) - Morphological evolution of limb reduction in squamate reptiles
- Mitchell Riegler (MS program) - Characterizing the microanatomy and isotopic signatures of squamate reptile dentition
- Emily Lessner - Archosauriform endocranial morphology and osteological evidence for semiaquatic sensory adaptations in phytosaurs
16. Li, C., Wu, X.-C., Zhao, L.-J., Nesbitt, S. J., Stocker, M. R., and Wang, L.-T. 2016. A new armored archosauriform (Diapsida: Archosauromorpha) from the marine Middle Triassic of China, with implications for the diverse ecologies of archosauriforms prior to diversification of crown Archosauria. The Science of Nature- Naturwissenschaften, DOI: 10.1007/s00114-016-1418-4
15. Stocker, M. R., Nesbitt, S. J., Criswell, K. E., Parker, W. G., Witmer, L. M., Rowe, Ridgely, R., T. B., and Brown, M. A. 2016. A dome-headed stem-archosaur exemplifies convergence among dinosaurs and their distant relatives. Current Biology, DOI: 10.1016/j.cub.2016.07.066.
14. Lessner, E. J.*, Stocker, M. R., Smith, N. D., Turner, A. H., Irmis, R. B., and Nesbitt, S. J. 2016. A new rauisuchid (Archosauria, Pseudosuchia) from the Upper Triassic (Norian) of New Mexico increases the diversity and temporal range of the clade. Peer J, DOI: 10.7717/peerj.2336.
13. Stocker, M. R. and Kirk, E. C. 2016. The first amphisbaenians from Texas with notes on other squamates from the Middle Eocene Purple Bench locality. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1094081.
12. Kammerer, C. F., Butler, R. J., Bandyopadhyay, S., and Stocker, M. R. 2015. Relationships of the Indian phytosaur Parasuchus hislopi Lydekker, 1885. Papers in Palaeontology, 1-23. DOI: 10.1002/spp2.1022.
11. Drumheller, S. K., Stocker, M. R., and Nesbitt, S. J. 2014. Direct evidence of trophic interactions between apex predators in the Late Triassic of western North America. Naturwissenschaften, 101:975-987. DOI 10.1007/s00114-014-1238-3.
10. Butler, R. J., Rauhut, O. W. M., Stocker, M. R., and Bronowicz, R. 2014. Redescription of the phytosaurs Paleorhinus (“Francosuchus”) angustifrons and Ebrachosuchus neukami from Germany, with implications for Late Triassic biochronology. Zoological Journal of the Linnean Society, 170:155-208. DOI: 10.1111/zoj.12094.
9. Bell, C. J., Stocker, M. R., and Parker, W. G. 2013. Preface: Festschrift for Wann Langston, Jr. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 103:187. DOI: http://dx.doi.org/10.1017/S1755691013000455.
8. Stocker, M. R. 2013. A new taxonomic arrangement for Paleorhinus scurriensis Langston, 1949. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 103:251-263. DOI: http://dx.doi.org/10.1017/S1755691013000340.
7. Martz, J. W., Mueller, B., Nesbitt, S. J., Stocker, M. R., Parker, W. G., Atanassov, M., Fraser, N., Weinbaum, J., and Lehane, J. 2013. A taxonomic and biostratigraphic re-evaluation of the Post Quarry vertebrate assemblage from the Cooper Canyon Formation (Dockum Group, Upper Triassic) of southern Garza County, western Texas. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 103:339-364. DOI: http://dx.doi.org/10.1017/S1755691013000376.
6. Stocker, M. R. and Butler, R. J. 2013. Phytosauria. In S. J. Nesbitt, J. B. Desojo, and R. B. Irmis (eds) Anatomy, Phylogeny and Palaeobiology of Basal Archosaurs and their Kin, Geological Society, London, Special Publications, 379:91-117. http://dx.doi.org/10.1144/SP379.5
5. Stocker, M. R. 2012. A new phytosaur (Archosauriformes, Phytosauria) from the Lot’s Wife beds (Sonsela Member) within the Chinle Formation (Upper Triassic) of Petrified Forest National Park, Arizona. Journal of Vertebrate Paleontology, 32:573-586.
4. Stocker, M. R. 2010. A new taxon of phytosaur (Archosauria: Pseudosuchia) from the Norian (Late Triassic) Sonsela Member (Chinle Formation) in Arizona, and a critical re-evaluation of Leptosuchus Case 1922. Palaeontology, 53:997-1022.
3. Nesbitt, S. J., Stocker, M. R., Small, B., and Downs, A. 2009. The osteology and relationships of Vancleavea campi (Reptilia: Archosauriformes). Zoological Journal of the Linnean Society, 157:814-864.
2. Nesbitt, S. J. and Stocker, M. R. 2008. The vertebrate assemblage of the Late Triassic Canjilon Quarry, (Northern New Mexico, USA) and the importance of apomorphy-based assemblage comparisons. Journal of Vertebrate Paleontology, 28(4):1063-1072.
1. Parker, W. G., Stocker, M. R., and Irmis, R. B. 2008. A new desmatosuchine aetosaur (Archosauria: Suchia) from the Upper Triassic Tecovas Formation (Dockum Group) of Texas. Journal of Vertebrate Paleontology, 28(3):692-701.
- 2016 Virginia Tech College of Science Outreach Excellence Award
- 2013 Climate Carbon and Geobiology Theme Graduate Student Best Paper, Jackson School of Geosciences (UT)
- 2011-2013 William Powers, Jr. Presidential Graduate Fellowship (UT; two awards)
- 2012 Albert W. and Alice M. Weeks Fund in Geology (UT)
- 2011-2012 Association for Women Geoscientists, Takken Scholarship, Membership
- 2010-2011 Outstanding Teaching Assistant Award, Jackson School of Geosciences (UT)
- 2010-2012 Francis L. Whitney Endowed Presidential Scholarship (UT; two awards)
- 2008 A. C. Trowbridge Award for Outstanding Master’s Candidate (UI)
- 2001 University Honors (UM)
- 1999-2001 Lloyd Hall Scholar (UM)
Our group is very involved in outreach across our campus and beyond. Examples of our activities include: exhibit design and construction in the Museum of Geosciences at Virginia Tech; participation in the annual Tech or Treat at Halloween; participation in the annual Virginia Science Festival; a “Paleo unpack” party where the public helps us organize fossils collected from our fieldwork. Additionally, we operate a volunteer program in our Fossil Preparation Laboratory. We currently have five full time volunteers working to help clean fossils from all over the world.”