Susannah Porter

Dr. Susannah Porter
Associate Professor
Vice Chair

Contact Phone


Office Location

Webb 1117


Precambrian and Cambrian Paleobiology, Early Eukaryote and Early Animal Evolution


Harvard University, Ph.D. Biology, 2002

Yale University, B.A. Mathematics, 1995, magna cum laude



The early evolution and radiation of eukaryotes and its relationship to environmental change, and the fossil record of the earliest skeletal animals. Research uses fieldwork, descriptive systematics, comparisons with modern taxa, paleoecological and taphonomic analyses, and stable isotopic studies.


Citation Summary: Google Scholar

Porter Lab Publications

* denotes student

Porter, S.M., and *Riedman, L. A. In press. Systematics of organic-walled microfossils from the ~780–740 Ma Chuar Group, Grand Canyon, Arizona. Journal of Paleontology. 

*Riedman, L. A. and S. M. Porter. In press. Organic-walled microfossils of the early to mid-Neoproterozoic Alinya Formation, Officer Basin, Australia. Journal of Paleontology.

Shields-Zhou, G., Porter, S.M., and Halverson, G.P. In press. A new rock-based definition for the Cryogenian Period (circa 720 – 635 Ma). Episodes.

Brocks, J. J., Jarrett, A.J.M., Sirantoine, E., Kenig, F., Moczydłowska, M., Porter, S. and Hope, J. 2015. Early sponges and toxic protists: possible sources of cryostane, an age diagnostic biomarker antedating Sturtian Snowball Earth. Geobiology. doi:10.1111/gbi.12165.

Vendrasco, M. J., Rodríguez-Navarro, A. B., Checa, A. G., Devaere, L., and Porter, S.M. 2015. To infer the early evolution of mollusc shell microstructures. Pp. 113-133 in Biomineralization: From Fundamentals to Biomaterials and Environmental Issues, Marin, F., Brümmer, F., Checa, A., Furtos, G., Lesci, I.G., and Siller, L. (eds.). Key Engineering Materials, v. 672. 

*Riedman, L. A., Porter, S. M., Halverson, G. P., Hurtgen, M. T., and Junium, C.K. 2014. Organic-walled microfossil assemblages from glacial and interglacial Neoproterozoic units of Australia and Svalbard. Geology 42:1011-1014. 

*Moore, J.L., Porter, S.M., and Li, G.. 2014. Two unusual small shelly fossils from the lower Cambrian of southeastern Shaanxi Province, China. Journal of Paleontology 88(2): 348-358.

*Moore, J.L., Li, G., and Porter, S.M. 2013. Chancelloriid sclerites from the Lower Cambrian (Meishucunian) of eastern Yunnan, China, and the early history of the group. Palaeontology 57: 833-878. 

Dehler, C. M., Porter, S.M., Timmons, M., and *Nagy, R.M. 2012. The Neoproterozoic Earth System revealed from the Chuar Group of Grand Canyon. M. Timmons and K. E. Karlstrom (eds.), Geological Overview of the Butte Fault/East Kaibab Monocline Area of Grand Canyon. Geological Society of America Special Papers, 489: 49-72.

Vendrasco, M. J., Kouchinsky, A., Porter, S. M., and C. Fernandez. 2011. Phylogeny and escalation in Mellopegma and other Cambrian molluscs.Palaeontologica Electronica 14(2):11A. link related blog post

Porter, S. M. 2011. The rise of predators. Geology 39:607-608. pdf

Maloof, A.C., Porter, S.M., *Moore, J.L., Dudás, F.Ö., Bowring, S.A., Higgins, J. A., Fike, D. A., , and M. P. Eddy. 2010. The earliest Cambrian record of animals and ocean geochemical change. GSA Bulletin 122 (11/12):1731-1774. pdf

*Moore, J. L. Porter, S. M., Steiner, M., and G. Li. 2010. Cambrothyra ampulliformis, an unusual coeloscleritophoran from the lower Cambrian of Shaanxi Province, China. Journal of Paleontology 84(6):1040-1060. link

Porter, S.M. 2010. Calcite and aragonite seas and the de novo acquisition of carbonate skeletons. Geobiology 8:256-277. link

Vendrasco, M. J., Porter, S. M., Kouchinsky, A. G., Li, G., and C. Z. Fernandez. 2010. Shell microstructures in early mollusks. Festivus 42: 43-54. pdf

Maloof, A. C., Ramezani, J., Bowring, S. A., Fike, D. A., Porter, S. M., and M. Mazouad. 2010. Constraints on early Cambrian carbon cycling from the duration of the Nemakit-Daldynian-Tommotian boundary d13C shift, Morocco. Geology38:623-626. pdf

Johnston, D. T., Poulton, S. W., Dehler, C. M., Porter, S. M., Husson, J., Canfield, D. E., and A. H. Knoll. 2010. An emerging picture of Neoproterozoic ocean chemistry: Insights from the Chuar Group, Grand Canyon, USA Earth and Planetary Science Letters 290: 64-73. link

Halverson, G. P., Hurtgen, M. T., Porter, S. M., and A. S. Collins. 2009. Neoproterozoic-Cambrian biogeochemical evolution. Pp. 351-365 in: Gaucher, C., Sial, A., Halverson, G. P., and H. Frimmel (eds.). Neoproterozoic-Cambrian Tectonics, Global Change and Evolution: A Focus on Southwestern Gondwana.Elsevier, Developments in Precambrian Geology Series. pdf

Vendrasco, M. J., Porter, S. M., Kouchinsky, A. G., Li, G., and C. Z. Fernandez. 2010. New data on molluscs and their shell microstructures from the middle Cambrian Gowers Formation, Australia. Palaeontology 53: 97-135. link

Vendrasco, M. J. Li, G., Porter, S. M., and C. Z. Fernandez. 2009. New data on the enigmatic Ocruranus-Eohalobia group of early Cambrian small skeletal fossils. Palaeontology 52:1373-1396. link

*Nagy, R. M., Porter, S. M., Dehler, C. M., and Y. Shen. 2009. Biotic turnover driven by eutrophication before the Sturtian low-latitude glaciation. Nature Geoscience 2:414-417. link

Porter, S. M. 2008. Skeletal microstructure indicates chancelloriids and halkeriids are closely related. Palaeontology 51(4): 865-879. pdf

Porter, S. M. 2007. Seawater chemistry and early carbonate biomineralization.Science 316:1302. link hi-res figure

Dehler, C. M., S.M. Porter, D. A Sprinkel, and L.D. DeGrey. 2007. The Neoproterozoic Uinta Mountain Group revisited: a synthesis of recent work on the Red Pine Shale and undivided clastic strata, northeastern Utah. Pp. 151-166 in Link, P.K., & Lewis, R. (eds.): Proterozoic Geology of Western North America and Siberia. SEPM Special Publication 86. pdf

Porter, S. M. 2006. The Proterozoic fossil record of heterotrophic protists. In Xiao, S., and Kaufman, A.J. (eds.), Neoproterozoic Geobiology. Geobiology Series. pdf

*Nagy, R.M., and S. M. Porter. 2005. Paleontology of the Neoproterozoic Uinta Mountain Group. In Dehler, C.M., Pederson, J.L., Sprinkel, D.A., and Kowallis, B.J. (eds.), Uinta Mountain Geology. Utah Geological Association Publication 33, p. 49-62. pdf

Dehler, C.M., D. A. Sprinkel, and S. M. Porter. 2005. Neoproterozoic Uinta Mountain Group of northeastern Utah: pre-Sturtian geographic, tectonic, and biologic evolution. In Pederson, J., and Dehler, C.M. (eds.), Interior Western United States. Geological Society of America Field Guide 6, p.1-26. pdf

Porter, S. M. 2004. Halkieriids in Middle Cambrian phosphatic limestones from Australia. Journal of Paleontology78(3): 574-590. pdf

Porter, S. M., A. H. Knoll, and P. Affaton. 2004. Chemostratigraphy of a Neoproterozoic ‘cap’ carbonate from the Volta Basin, West Africa. Precambrian Research 130: 99-112. pdf

Porter, S. M. 2004. Closing the ‘phosphatization window’: implications for interpreting the record of small shelly fossils. Palaios 19: 178-183. pdf

Porter, S. M. 2004. The fossil record of early eukaryotic diversification.Paleontological Society Papers 10: 35-50. pdf

Porter, S. M., R. Meisterfeld, and A. H. Knoll. 2003. Vase-shaped microfossils from the Neoproterozoic Chuar Group, Grand Canyon: a classification guided by modern testate amoebae. Journal of Paleontology 77(3): 409-429. link (jstor)

Porter, S. M., and A. H. Knoll. 2000. Neoproterozoic testate amoebae: evidence from vase-shaped microfossils in the Chuar Group, Grand Canyon. Paleobiology26(3): 360-385. link (jstor)

Karlstrom, K. E., S. A. Bowring, C. M. Dehler, A. H. Knoll, S. M. Porter, D. J. Des Marais, A. B. Weil, Z. D. Sharp, J. W. Geissman, M. B. Elrick, J. M. Timmons, L. J. Crossey, and K. L. Davidek. 2000. Chuar Group of the Grand Canyon: record of breakup of Rodinia, associated change in the global carbon cycle, and ecosystem expansion by 740 Ma. Geology 28: 619-622. pdf

Dehler, C., S. Porter, and K. Karlstrom. 1999. Grand Canyon Supergroup. Grand Canyon River Guides 12(3): 31-35.


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Introduction to the science of the Earth; properties and processes of its surface and interior, including plate tectonics, volcanism, earthquakes, glaciation, mountain building, formation of rocks, minerals, and the structural basis of landforms. 


Earth 7: Age of Dinosaurs

The origin and diversification of dinosaurs, and the evolutionary relationship of dinosaurs (including their living descendents) to other major groups of vertebrates. Broad introduction including discussion of dinosaur ecology, anatomy, extinction, and paleogeography. 


Earth 111/EEMB 136: Principles of Paleontology (with Prof. Bruce Tiffney)

The ecologic structure and evolution of the biosphere as illustrated by the fossil record. 


Earth 143: The Early Evolution of Life and its Environmental Context

The first 3.5 billion years of life and the environmental context in which it evolved. Highly multidisciplinary, drawing on evidence from geology, geochemistry, paleontology, and comparative biology. 


Earth 144: Invertebrate Paleontology

Important topics in paleobiology are discussed in the context of the evolutionary history of invertebrate animal life. These include macroevolutionary theory, diversification and extinction events, ecological and geobiological interactions through time, and the incompleteness of the fossil record. 


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