Mark Webster
Assistant Professor of Paleobiology
Phone: (773) 702-4071
Email: mwebster@geosci.uchicago.edu
Office #: 233
Research interests:
My research focuses on the understanding of modes and constraints in morphological evolution at the microevolutionary scale, and how these affect parameters of clade diversification such as evolutionary rate, evolutionary trends, and morphospace occupation at a macroevolutionary scale. My primary interest lies in the Trilobita, a group offering outstanding opportunities for studying the details of morphological evolution in a tightly constrained phylogenetic, environmental, temporal, and geological framework over short and long time intervals. The work involves detailed comparative analysis of the morphological variation, ontogenetic development, functional morphology, and systematics of trilobite species, employing and developing cutting-edge methods in morphometrics and cladistics. The significance of my work lies in the detail in which it is conducted, which allows unprecedented insight into evolutionary mechanisms and constraints - the implications of which extend well beyond trilobite evolution. High-resolution (sub-meter scale) stratigraphic collecting permits patterns of morphological evolution to be framed within paleoenvironmental and sequence stratigraphic context, thus producing an integrative approach to stratigraphic paleobiology. The research forms important contributions to Cambrian paleontology and biostratigraphy, and has far-reaching implications for the broader fields of paleobiology, evolutionary developmental biology, and the integration of stratigraphy and morphometrics with cladistics.
Publications:
Webster, M., and M. L. Zelditch. 2011. Evolutionary lability of integration in Cambrian ptychoparioid trilobites.Evolutionary Biology 38: 144-162. [PDF Link][Link to R code]
Webster, M., and M. L. Zelditch. 2011. Modularity of a Cambrian ptychoparioid trilobite cranidium. Evolution & Development 13 (1): 96-109. [PDF Link]
Webster, M. 2011. The structure of cranidial shape variation in three early ptychoparioid trilobite species from the Dyeran-Delamaran (traditional "Lower-Middle" Cambrian) boundary interval of Nevada, U. S. A. Journal of Paleontology 85 (2): 179-225. [Request a PDF]
Webster, M. 2011. Upper Dyeran trilobite biostratigraphy and sequence stratigraphy in the southern Great Basin. Pp. 121-154 in J. S. Hollingsworth, F. A. Sundberg, and J. R. Foster (eds.), Cambrian Stratigraphy and Paleontology of Northern Arizona and Southern Nevada. Museum of Northern Arizona Bulletin 67. Flagstaff, Arizona. [PDF Link]
Webster, M. 2011. Litho- and biostratigraphy of the Dyeran-Delamaran boundary interval at Frenchman Mountain, Nevada. Pp. 195-203 in J. S. Hollingsworth, F. A. Sundberg, and J. R. Foster (eds.), Cambrian Stratigraphy and Paleontology of Northern Arizona and Southern Nevada. Museum of Northern Arizona Bulletin 67. Flagstaff, Arizona. [PDF Link]
Webster, M. 2011. Litho- and biostratigraphy of the Dyeran-Delamaran boundary interval in the Pioche-Caliente region, Nevada. Pp. 203-215 in J. S. Hollingsworth, F. A. Sundberg, and J. R. Foster (eds.), Cambrian Stratigraphy and Paleontology of Northern Arizona and Southern Nevada. Museum of Northern Arizona Bulletin 67. Flagstaff, Arizona. [PDF Link]
Webster, M., L. B. McCollum, and F. A. Sundberg. 2011. Upper Dyeran and Lower Delamaran litho- and biostratigraphy of the northern Groom Range, Nevada. Pp. 226-236 in J. S. Hollingsworth, F. A. Sundberg, and J. R. Foster (eds.), Cambrian Stratigraphy and Paleontology of Northern Arizona and Southern Nevada. Museum of Northern Arizona Bulletin 67. Flagstaff, Arizona. [PDF Link]
Webster, M. 2011. Upper Dyeran litho- and biostratigraphy of the Split Mountain area, Nevada. Pp. 236-246 in J. S. Hollingsworth, F. A. Sundberg, and J. R. Foster (eds.), Cambrian Stratigraphy and Paleontology of Northern Arizona and Southern Nevada. Museum of Northern Arizona Bulletin 67. Flagstaff, Arizona. [PDF Link]
Webster, M., and H. D. Sheets. 2010. A practical introduction to landmark-based geometric morphometrics. Pp. 163-188 in J. Alroy and G. Hunt (eds.), Quantitative Methods in Paleobiology. Paleontological Society Papers, Volume 16. [PDF Link]
Webster, M. 2009. Systematic revision of the Cambrian trilobite Bathynotus Hall, 1860, with documentation of new occurrences in western Laurentia and implications for intercontinental biostratigraphic correlation. Memoirs of the Association of Australasian Paleontologists 37: 369-406. [PDF Link]
Hopkins, M. J., and M. Webster. 2009. Ontogeny and geographic variation of a new species of the corynexochine trilobite Zacanthopsis (Dyeran, Cambrian). Journal of Paleontology 83 (4): 524-547. [Request a PDF]
Webster, M. 2009. Ontogeny, systematics, and evolution of the effaced early Cambrian trilobites Peachella Walcott, 1910 and Eopeachella new genus (Olenelloidea). Journal of Paleontology 83 (2): 197-218. [Request a PDF]
Webster, M., and M. L. Zeldtich. 2008. Integration and regulation of developmental systems in trilobites. Pp. 427-433 in Rábano, I., Gozalo, R., and García-Bellido, D (eds.), Advances In Trilobite Research. Cuadernos del Museo Geominero 9. Instituto Geológico y Minero de España, Madrid. [PDF LINK]
Hopkins, M. J., and M. Webster. 2008. Morphological and ontogenetic change in the "Early" Cambrian trilobite Zacanthopsis during an interval of environmental change. Pp. 185-187 in Rábano, I., Gozalo, R., and García-Bellido, D (eds.), Advances In Trilobite Research. Cuadernos del Museo Geominero 9. Instituto Geológico y Minero de España, Madrid. [PDF LINK]
Webster, M., R. R. Gaines, and N. C. Hughes. 2008. Microstratigraphy, trilobite biostratinomy, and depositional environment of the "Lower Cambrian" Ruin Wash Lagerstätte, Pioche Formation, Nevada. Palaeogeography, Palaeoclimatology, Palaeoecology 264: 100-122. [Request a PDF]
Webster, M. 2007. Paranephrolenellus, a new genus of Early Cambrian olenelloid trilobite. Memoirs of the Association of Australasian Paleontologists 34: 31-59. [PDF LINK]
Webster, M. 2007. Ontogeny and evolution of the Early Cambrian trilobite genus Nephrolenellus (Olenelloidea). Journal of Paleontology 81 (6): 1168-1193. [PDF LINK]
Webster, M. 2007. A Cambrian peak in morphological variation within trilobite species. Science 317: 499-502. [PDF LINK]
Webster, M., and M. L. Zelditch. 2005. Evolutionary modifications of ontogeny: heterochrony and beyond. Paleobiology 31 (3): 354-372. [PDF Link]
Fusco, G., N. C. Hughes, M. Webster, and A. Minelli. 2004. Exploring developmental modes in a fossil arthropod: growth and trunk segmentation of the trilobite Aulacopleura konincki. American Naturalist 163 (2): 167-183.
Webster, M., P. M. Sadler, M. A. Kooser, and E. Fowler. 2003. Combining stratigraphic sections and museum collections to increase biostratigraphic resolution: Application to Lower Cambrian trilobites from southern California. Pp. 95-128 in P. J. Harries (ed.), High-Resolution Approaches in Stratigraphic Paleontology. Topics in Geobiology, Volume 21. Kluwer Academic Publishers, Dordrecht.
Webster, M., H. D. Sheets, and N. C. Hughes. 2001. Allometric patterning in trilobite ontogeny: Testing for heterochrony in Nephrolenellus. Pp. 105-144 in M.L. Zelditch (ed.), Beyond Heterochrony: The Evolution of Development. John Wiley and Sons, New York.
Dunlop, J. and M. Webster. 1999. Fossil evidence, terrestrialization and arachnid phylogeny. Journal of Arachnology 27: 86-93.
Webster, M., and N. C. Hughes. 1999. Compaction-related deformation in Cambrian olenelloid trilobites and its implications for fossil morphometry. Journal of Paleontology 73: 355-371.
Bowden, A., M. Webster, and T. Mitcham. 1997. Salthill Quarry Geology Trail. Geologists' Association Guide No. 58. Geologists' Association, London. 30 pp.
Graduate Students Supervised
Annat Haber. Ph.D. 2010. Morphological integration in the ruminant skull: macroevolutionary aspects.
Melanie Hopkins. Ph.D. 2010. Species-level variation, its geographic structure, and the relationship between variation and duration, with examples from Cambrian trilobites and fiddler crabs.
Tyler Mason. M.Sc. 2010. Crushing strength of modeled Cambrian trilobite thoracic segments.
Courses:
Undergraduate Courses
Geos 26300: Invertebrate Paleobiology and Evolution (with field trip).
Geos 28100: Field Course in Geology.
Graduate Courses
Geos 36000: Morphometrics.
Geos 36200: Evolution and the Fossil Record.
Education:
2003: University of California, Riverside (U.S.A.). Postdoctoral research position with P. M. Sadler (January to July).
1998-2002: University of California, Riverside (U.S.A.). Ph.D. Degree. Ontogeny and Phylogeny of Early Cambrian Olenelloid Trilobites, with Emphasis on the Late Dyeran Biceratopsidae. (Degree conferred March 2003)
1996-1998: University of California, Riverside (U.S.A.). M.S. Degree. Paleobiologic Aspects of Olenelloid Trilobites from the Uppermost Dyeran C-Shale Member of the Pioche Formation, Nevada. (August 1996 to August 1997 spent at the University of Cincinnati, Ohio).
1993-1996: University of Manchester (England). First Class B.Sc. Degree with Honors in Biology and Geology.
Employment:
2004-present: University of Chicago (U.S.A.). Assistant Professor of Paleobiology, Department of the Geophysical Sciences, and Committee on Evolutionary Biology (from July 2004).
2003-2004: University of California, Los Angeles (U.S.A.). Assistant Professor of Paleobiology, Department of Earth and Space Sciences.