The cartilaginous fishes have persisted through four mass extinctions (so far), and yet taphonomy often obscures the fossil record of their skeletal architecture. Using CT scanning, I reconstruct rare well-preserved chondrichthyan skeletons, particularly those from the Late Mississippian Fayetteville Shale (in what is now Arkansas, Oklahoma, and Texas).  Development of morphological characters from these and other well-preserved skeletons has led to ongoing efforts to resolve the chondrichthyan tree of life, with a critical assessment of methodology for morphology-based tree estimation. This work is in collaboration with Dr. John Maisey (American Museum of Natural History), Dr. Alan Pradel (Muséum national d'histoire naturelle), and other sharky colleagues around the world.

Recent Related Papers:

A.W. Bronson, P. Gueriau, A. Pradel, J.G. Maisey, N. Landman, and R. Mapes. 2026. Vertebrate fauna and depositional environment of the Fayetteville Shale (Upper Mississippian, Middle Chesterian). Geobios 94(February 2026): 1-18. https://doi.org/10.1016/j.geobios.2025.11.002 

BRONSON, A., A. Pradel, J. Denton, and J. Maisey. 2024. A new operculate symmoriiform chondrichthyan from the Late Mississippian Fayetteville Shale (Arkansas, USA). Geodiversitas 46(4):101-117. https://doi.org/10.5252/geodiversitas2024v46a4  

The shape of the inner ear (the skeletal labyrinth housing the semicircular canals) has been correlated with habitat and locomotion in several tetrapod groups. We seek to understand whether a similar ecomorphological correlation exists in the ear of cartilaginous fishes, and to use inner ear characters to improve morphology-based phylogenetic inference within the chondrichthyan crown group. 

The inner ear of modern sharks contains numerous specializations for low frequency sound detection (LFSD). How early in shark evolution did these traits arise? Reconstructing early chondrichthyan fossils can help us elucidate the time and nature of this transition.

 A huge collaborative effort spanning every living family of cartilaginous fishes, this work includes: graduate and undergraduate researchers at Cal Poly Humboldt, colleagues at the University of Michigan and University of North Carolina, and contributions of hundreds of specimens' CT data, thanks to collections managers worldwide.

Recent Related Papers (* denotes student authors):

K. Dodd*, I. Lopez-Argueta*, M. Edwards-Silva*, L. Kim*, A. Palomera*, and A.W. Bronson. 2026. Comparative morphology of the skeletal labyrinth in extant squalomorph sharks. The Anatomical Record (in press).

J. Neal*, S. Rodrigues*, J. Denton, and A.W. Bronson. 2024. Skeletal Labyrinth Morphology of Four Species of Living Elasmobranchs. The Anatomical Record, 1-12. https://doi.org/10.1002/ar.25582 

With great [anatomy nerd] power comes great responsibility." 

- Spider-Man Amazing Fantasy #15 (1962)

Research in the lab spans a wide range of taxonomic groups, including sensory anatomy of freshwater catfish and anadromous salmonids, developmental anatomy of sturgeon, and ichthyoplankton surveys. We know startlingly little about most species' basic biology. Our lab aims to make a little headway in that regard, contextualizing anatomical innovations of local fishes within evolutionary time and ecological circumstances.

Recent Related Papers:

A.W. Bronson and M.L.J. Stiassny. 2025. Novel nasal anatomy suggests enhanced olfactory capability in Parauchenoglanis punctatus (Claroteidae, Auchenoglanidinae). Ichthyology & Herpetology 113(2): 233-243. https://doi.org/10.1643/i2024062

Frable, B., C. Seid, A.W. Bronson, and P.R. Møller. 2023. A new deep-sea eelpout of the genus Pyrolycus (Zoarcidae: Lycodinae) associated with a hydrothermal seep on the Pacific margin of Costa Rica. Zootaxa. DOI: 10.11646/ZOOTAXA.5230.1.5; http://zoobank.org/urn:lsid:zoobank.org:pub:0F90B9EF-58FA-4E54-B9E4-D6975DB8E58C