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field programs:

Investigating synapsid community evolution through time

Western North America: How did late Paleozoic climate warming and rainforest collapse affect the expansion of  vertebrate communities in western Pangea?

Sometimes referred to as Earth's penultimate ice age, the Carboniferous-Permian (C-P) transition (ca. 300 million years ago) represents our best deep-time analog of present day climate warming. At its onset, the southern hemisphere was largely glaciated and cool-temperate forests were apparently wide spread, even at near equatorial latitudes. Late Paleozoic redbeds in western Colorado's Eagle Basin (right) and Utah's Paradox Basin record increasing continental aridity in westernmost Pangea by earliest Permian times, and their vertebrate fossils record major events in life's history, including diverse amphibian and synapsid fossils that included the first large-bodied herbivores. Many of these sites in southern Utah are part of the newly declared Bears Ears National Monument. We are working toward a better understanding of vertebrate biochronology in the region by placing these fossils into their proper stratigraphic context.


Terrestrial redbeds of the Maroon and Chinle formations on the Colorado River, Eagle Basin, western Colorado.

Southern Africa: How did synapsid communities rebound in the aftermath of the Permo-Triassic mass extinction?

About thirty million years before the dinosaurs and their relatives (“archosaurs”) took center stage as Earth’s major charismatic megafauna, the Permian period ended with a lasting global biodiversity crisis that disrupted links in animal communities both on land and in the seas: the "end-Permian" or "Permo-Triassic" mass extinction (ca. 252 million years ago). The best record of this extinction comes from the Karoo Basin and equivalent basins in southern Africa. I have been fortunate to work with South African collaborators (Jennifer Botha, National Museum, Bloemfontein), documenting synapsid diversity and extinction selectivity at fossil sites throughout the Karoo. Our work emphasizes the timing of the mass extinction and its synchrony with marine extinctions documented elsewhere around the globe (Botha et al., Palaeo3, 2020).


Me and everyone's favorite sail-backed synapsid, Dimetrodon. (Pictured at the Houston Museum of Natural Science)

recent Field work

  • Bears Ears National Monument, Utah, USA (2014-2024)

  • Central & western Colorado, USA (Central Colorado Trough & Eagle Basin) (2004, 2005, 2013-2015, 2017, 2019)

  • Petrified Forest National Park (Triassic Chinle Formation), Arizona, USA (2014, 2015)

  • Central Transantarctic Mountains (Permian through Jurassic) (2010-2011)

  • Karoo Basin (Permian-Triassic), South Africa (2010, 2015)

  • Argana Basin (Carboniferous through Triassic), Morocco (2009)

  • Forest City Basin (Carboniferous-Permian), Nebraska & Kansas, USA (2005, 2008, 2009)

Related publications & abstracts

  • Botha, J., Huttenlocker, A. K., Smith, R. M., Prevec, R., Viglietti, P., & Modesto, S. P. 2020. New geochemical and palaeontological data from the Permian-Triassic boundary in the South African Karoo Basin test the synchronicity of terrestrial and marine extinctions. Palaeogeography, Palaeoclimatology, Palaeoecology, 540:109467.

  • Gay, R. J., Huttenlocker, A. K., Irmis, R. B., Stegner, M. A., and Uglesich, J. 2020. Paleontology of Bears Ears National Monument (Utah, USA). Geology of the Intermountain West 7: 205-241.

  • Pardo, J. D., B. J. Small, A. R. Milner, and A. K. Huttenlocker. 2019. Carboniferous-Permian climate change constrained early land vertebrate radiations. Nature Ecology & Evolution 3(2):200–206. doi: 10.1038/s41559-018-0776-z

  • Huttenlocker, A. K., D. M. Grossnickle, J. I. Kirkland, J. A. Schultz, and Z.-X. Luo. 2018. Late-surviving stem mammal links the lowermost Cretaceous of North America and Gondwana. Nature 558:108–112. 10.1038/s41586-018-0126-y

  • Huttenlocker, A. K., D. S. Berman, S. Elrick, A. Henrici, W. J. Nelson, T. Schlotterbeck, and S. Sumida. 2018. A multitaxic bonebed near the Carboniferous-Permian boundary (Halgaito Formation, Cutler Group) in Valley of the Gods, Utah, USA: Vertebrate paleontology and taphonomy . Palaeogeography, Palaeoclimatology, Palaeoecology 499:72–92. doi:10.1016/j.palaeo.2018.03.017

  • Huttenlocker, A. K., and R. M. H. Smith. 2017. New whaitsioids (Therapsida: Therocephalia) from the Teekloof Formation of South Africa and therocephalian diversity during the end-Guadalupian extinction. PeerJ 5:e3868. doi:10.7717/peerj.3868

  • Pardo, J. D., B. J. Small, and A. K. Huttenlocker. 2017. Stem caecilian from the Triassic of Colorado sheds light on the origins of Lissamphibia. Proceedings of the National Academy of Sciences of the United States of America 114:201706752. doi:10.1073/pnas.1706752114 [Top 10 New Fossils of 2017, PLOS]

  • Codron, J., J. Botha-Brink, D. Codron, A. K. Huttenlocker, and K. D. Angielczyk. 2017. Predator-prey interactions among Permo-Triassic terrestrial vertebrates as a deterministic factor influencing faunal collapse and turnover. Journal of Evolutionary Biology 30:40–54. doi:10.1111/jeb.12983

  • Huttenlocker, A. K., and C. A. Sidor. 2016. The first karenitid (Therapsida, Therocephalia) from the upper Permian of Gondwana and the biogeography of Permo-Triassic therocephalians. Journal of Vertebrate Paleontology 36:e1111897. doi:10.1080/02724634.2016.1111897

  • Huttenlocker, A. K., and F. Abdala. 2016. Revision of the first therocephalian, Theriognathus Owen (Therapsida: Whatsiidae), and implications for cranial ontogeny and allometry in nonmammaliaform eutheriodonts. Journal of Paleontology 89:645–664. doi:10.1017/jpa.2015.32

  • Huttenlocker, A. K., C. A. Sidor, and K. D. Angielczyk. 2015. A new eutherocephalian from the upper Madumabisa Mudstone Formation (Upper Permian) of Zambia. Journal of Vertebrate Paleontology 35:e969400. doi:10.1080/02724634

  • Pardo, J. D., A. K. Huttenlocker, and B. J. Small. 2014. An exceptionally preserved transitional lungfish from the Lower Permian of Nebraska, USA, and the origin of modern lungfishes. PLOS ONE 9:e108542. doi:10.1371/journal.pone.0108542

  • Huttenlocker, A. K., J. D. Pardo, B. J. Small, and J. S. Anderson. 2013. Cranial morphology of recumbirostrans from the Permian of Kansas and Nebraska, and early morphological evolution inferred by micro-computed tomography. Journal of Vertebrate Paleontology 33:540–552. doi:10.1080/02724634.2013.728998

  • Benca, J., C. Strömberg, & A. Huttenlocker. 2013. Do leaf margin-climatic proxies exist for the Paleozoic? New Mexico Museum of Natural History and Science Carboniferous-Permian Transition Symposium, Albuquerque.

  • May, W., A. K. Huttenlocker, J. D. Pardo, J. Benca, & B. J. Small. 2011. New Upper Pennsylvanian armored dissorophid records (Temnospondyli: Dissorophoidea) from the US midcontinent and the stratigraphic distributions of dissorophids. Journal of Vertebrate Paleontology 31:907-912.

  • Huttenlocker, A. K., J. D. Pardo, B. J. Small, & A. Milner.  2008. Biotic responses to climate change in the Permo-Carboniferous transition, Part 2: Beta diversity, regional responses, and Vaughn’s faunal cline.  Society of Vertebrate Paleontology 68th Annual Meeting, Cleveland.

  • Pardo, J. D., A. K. Huttenlocker, B. J. Small, & A. Milner.  2008. Biotic responses to climate change in the Permo-Carboniferous transition, Part 1: Vertebrate faunal distributions and regional provincialism.  Society of Vertebrate Paleontology 68th Annual Meeting, Cleveland.

  • Englehorn, J., B. J. Small, & A. Huttenlocker. 2008. Anatomy and relationships of Acroplous vorax (Amphibia: Dvinosauroidea): new specimens from the Lower Permian of Nebraska and Kansas. Journal of Vertebrate Paleontology 28:291-305.

  • Huttenlocker, A. K., B. J. Small, & J. Pardo. 2007. Plemmyradytes shintoni gen. et sp. nov., an Early Permian amphibamid (Temnospondyli: Dissorophoidea) from the Eskridge Formation, Nebraska. Journal of Vertebrate Paleontology 27:316-328

  • Small, B. J., J. D. Pardo, & A. K. Huttenlocker. 2006. Taxonomic diversity of estivating species in the lowest Permian of North America: onset of seasonality and comments on physiological plasticity. Society of Vertebrate Paleontology 66th Annual Meeting, Ottawa.

  • Huttenlocker, A. K., J. D. Pardo, & B. J. Small. 2005. An earliest Permian nonmarine vertebrate assemblage from the Eskridge Formation, Nebraska. Pp. 133-143 in S. G. Lucas and K. E. Ziegler (eds.) The Nonmarine Permian: Bulletin of the New Mexico Museum of Natural History and Science 30.

  • Huttenlocker, A. K., J. Pardo, & B. J. Small.  2005.  An earliest Permian nonmarine vertebrate assemblage from the Eskridge Formation (Council Grove Group), Nebraska.  New Mexico Museum of Natural History and Science Nonmarine Permian Symposium, Albuquerque.

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