I’m an Associate Professor of Teaching at USC, and I teach general biology and human biology. I’m originally from Norway, and receieved my PhD from McGill University, Canada.
Summary Statement of Research Interests
My main research interests include the phylogenetics and evolutionary origins of major vertebrate taxa, as well as the functional anatomy of these animals. I have worked extensively on the evolution and biology of amphibians, birds, and mammals, and some of this work was done together with my mentor, the great late Prof. Robert Carroll (Sigurdsen, Carroll, 2016). I combine tried and true methods, such as specimen drawings and anatomical descriptions, with state of the art technology and software. The latter include parsimony-based or Bayesian phylogenetic analyses, as well as high resolution x-ray computed tomography (CT).
I am currently working with Dr. Luis Chiappe at the Natural History Museum of Los Angeles County. Together with our coauthors in China, we published papers detailing the anatomy of fossil Chinese Enantiornithine birds and clarified phylogenetic aspects of this ancient group (Zhang, O’Connor, Sigurdsen, Chiappe, 2014; Chiappe, Qinjing, Serrano, Sigurdsen, Min, Bell, Di, 2019). Furthermore, I made a database of wing bone measurements, containing both modern birds as well as fossil forms. This way we compared the skeletal wing anatomy and morphometrics in modern birds to that of extinct forms, providing new information on the macroevolutionary patterns in the evolution of the bones of the bird wing (Nebreda, Navalón, Menéndez, Sigurdsen, Chiappe, Marugán-Lobón, 2020).
I am very interested in the relationships of mammals to the non-mammalian synapsids. My focus on the early evolution of mammals goes back to their “reptile-like” basal synapsid ancestors (non-mammalian Synapsida, or “mammal-like reptiles”) of the Paleozoic and Mesozoic. In this regard I have been interested in possible anatomical correlates of endothermic metabolism, a feature that is of interest in the study of both birds and mammals. I am studying fossil forms using CT-scanning to reveal osseous structures of the skull and braincase. This will expand upon work on therocephalian therapsids published in the Journal of Vertebrate Paleontology (Sigurdsen et al., 2012).
Nebreda SC, Navalón G, Menéndez I, Sigurdsen T, Chiappe LM, Marugán-Lobón J. 2020. Disparity and Macroevolutionary Transformation of the Maniraptoran Manus. Bulletin of the American Museum of Natural History. 440 (Pennaraptoran Theropod Dinosaurs: Past Progress and New Frontiers): 183-203.
Chiappe LM, Qinjing M, Serrano F, Sigurdsen T, Min W, Bell A, Di L. 2019. New Bohaiornis-like bird from the Early Cretaceous of China: Enantiornithine interrelationships and flight performance. PeerJ 7:e7846 DOI 10.7717/peerj.7846
Sigurdsen T, Carroll R. 2016. The origin of amniotes. Pp. 63- 69 in: Kliman RM (ed.) Encyclopedia of Evolutionary Biology Vol 1. Elsevier (2132p. 4 vols.)
Zhang Y, O’Connor J, Di L, Qingjin M, Sigurdsen T, Chiappe LM. 2014. New information on the anatomy of the Chinese Early Cretaceous Bohaiornithidae (Aves : Enantiornithes) from a subadult specimen of Zhouornis hani. PeerJ 407: 1-19. DOI 10.7717/peerj.407 (4 citations)
Sigurdsen T, Green D, Bishop PJ. 2012 (invited publication). Did Triadobatrachus jump? Morphology and evolution of the anuran forelimb in relation to locomotion in early salientians. Fieldiana: Life and Earth Sciences (Special volume dedicated to John R. Bolt) 5:77-89 Eds: Ruta M, Anderson J, Lombard E, Sumida S. (10 citations)
Sigurdsen T, Huttenlocker A, Modesto S, Rowe T, Damiani R. 2012. Reassessment of the morphology and paleobiology of the therocephalian Tetracynodon darti (Therapsida) based on CT-scanning, and the phylogenetic relationships of Baurioidea. Journal of Vertebrate Paleontology 32 (5):1113-1134. (20 citations)