My research combines the disciplines of paleontology, comparative anatomy, and development to formulate and test phylogenetic hypotheses of vertebrate interrelationships. I am particularly concerned with assessing the role that fossils play in the interpretation of modern biodiversity and phylogenetics, as well as the role that phenotypic variation plays in the interpretation of vertebrate fossils and systematics. My studies include morphological changes across ontogeny and over deep time, which offer a way to investigate pattern and process in evolution, and help to generate more comprehensive hypotheses about how form and function interact. I make extensive use of museum collections worldwide for my specimens based research.


Much of my research has focused on cartilaginous and bony fishes. Fishes are a practically ubiquitous group of vertebrate with the potential to help formulate hypotheses for every other group of vertebrate known. With the propensity for an even distribution across a vast geographic area, biostratigraphic data for other vertebrates can be enhanced dramatically.


Claeson, K. M., J. T. Eastman, and R. MacPhee. 2012. Definitive specimens of Merlucciidae (Gadiformes) from the Eocene of Seymour Island. Antarctic Science. First view link  

Aschliman, N. C., K. M. Claeson, J. D. McEachran. 2012. Phylogeny of Batoidea, pp. 57–96 in J. C. Carrier, J. A. Musick and M. R. Heithaus (eds.), Biology of Sharks and Their Relatives, Edition 2. CRC Press, Boca Raton, Florida.

Claeson, K. M. 2011. The synarcual cartilage of batoids with emphasis on the synarcual of Rajidae. Journal of Morphology. 272: 1444-1463. link

Witzmann, F., K. M. Claeson, O. Hampe, M. Niederhagen, P. Asbach. 2011. Indirect evidence of viral existence in the fossil record: Paget disease in a Jurassic dinosaur. Current Biology 21: R647-R648. pdf

Claeson, K. M. and A. Hilger. 2011. Morphology of the anterior vertebral region in elasmobranchs: special reference, Squatiniformes. Fossil Record 14:129–140. pdf

Claeson, K. M. and M. N. Dean. 2011. Cartilaginous fish skeletal anatomy: Chondrichthyes we have known. In: Encyclopedia of Fish Physiology: From Genome to Environment, A. P. Farrell (ed.), volume 1, pp. 419–427. San Diego: Academic Press.

Claeson, K. M., D. J. Ward, and C. J. Underwood. 2010. 3D digital imaging of a concretion-preserved batoid (Chondrichthyes, Elasmobranchii) from the Turonian of Morocco. Comptes Rendus Palevol, 9: 283–287. link

Claeson, K. M., M. D. Gottfried, E. M. Roberts, F. Sissoko, M. Bouare, L. Tapanila, D. Goodwin, and M. A. O’Leary. 2010. First Mesozoic record of eagle rays (Rajiformes: Myliobatidae: Myliobatinae) new evidence from the Late Cretaceous of Mali. Acta Palaeontologica Polonica, 55: 655–674. link

Claeson, K. M. 2008. Variation of the synarcual in the California Ray, Raja inornata (Elasmobranchii: Rajidae). Conference Proceedings on Evolution and diversity of chondrichthyans. Acta Geologica Polonica, 58:121–126. pdf

Claeson, K. M. and J. W. Hagadorn. 2008. The occipital region in the basal bony fish Erpetoichthys calabaricus (Actinopterygii: Cladistia). Journal of Fish Biology. 73:1075–1082. link

Claeson, K. M., J. W. Hagadorn, K. Luckenbill, and J. G. Lundberg. 2008. Skeletal morphology of Sarcoglanis simplex and a cladistic analysis of the Sarcoglaninae. Paleontologica Electronia, 11:6A:11p;

Claeson, K. M., J. W. Hagadorn, and W. E. Bemis. 2007. New interpretations of the skull of a primitive bony fish; Erpetoichthys calabaricus (Actinopterygii: Cladistia). Journal of Morphology. 268:1021–1039. link

Apesteguía, S., F. L. Agnolín, and K. Claeson. 2007. Review of Cretaceous dipnoans from Argentina (Sarcopterygii: Dipnoi) with descriptions of new species. Revista del Museo Argentino de Ciencias Naturales "Bernardino Rivadavia" 9:27–40. pdf

Bobbing for fish: it’s a blast.