Jules Walter

My research interests focus on the study of extinct crocodylomorph diversity, using cladistic methods and comparative anatomy. This work aims to recover evolutionary relationships between species and families, but also try to better understand past biogeography.

•    Early appearance and diversification of the caiman family in American continents
•    Revision of the poorly known taxon Eopneumatosuchus colberti, from the Early Jurassic of Arizona

“Re-description and evolutionary relationships of Eopneumatosuchus colberti”

Crocodylomorpha clade appeared some 220 million years ago, during the Upper Triassic. The diversification of their representatives into “true crocodylians” occurs in the Early Jurassic. Among basal crocodylomorphs is Eopneumatosuchus colberti, known from a single specimen, which is Early Jurassic in age. The fossil was collected in 1979 at the base of the Kayenta Formation (Glen Canyon Group. Lower Jurassic, Sinemurian-Pliensbachian age). The precise site is located North-East to Cameron, Coconino County, Arizona. Alfred W. Crompton and Kathleen K. Smith published the first and only paper describing the specimen in 1980. Indeed, no other material was assigned to the genus since its discovery. Thus, the holotype consists in a fairly well-preserved braincase and the posterior region of the rostrum roof. The first aim of my Master dissertation was to update the description of the species using modern methods, such as CT scans and high-resolution photos. This step was very important in order to score the specimen accurately. I used high-resolution photos along with CT scans to complete this task.
My second aim was to assess the phylogenetic position of Eopneumatosuchus colberti and infer its evolutionary relationships. The updated scoring was then used to run new phylogenetic analyses. Phylogenies recovered from these analyses placed it in two different positions: either as a sister taxon to marine crocodylomorphs from the Mesozoic (Thalattosuchia), or as a basal crocodyliform (Protosuchia). These results were somewhat different than what the morphology tells us. Eopneumatosuchus colberti bears features from both groups. Its small size and age are consistent with protosuchian grade species, but braincase cavities and flat skull roof argues for a more derived position. Undergoing investigation will bring new insights about Eopneumatosuchus colberti evolutionary relationships. Material incompleteness is an issue for this species (a significant amount of characters cannot be scored) and addition of new specimens would definitely help future work. In the meantime, Eopneumatosuchus colberti might still retain some of its mystery.
 

2018 – 2019: Master of Science by Research in Paleobiology and Geobiology, University of Edinburgh, Scotland, United-Kingdom
2015 – 2018: “Licence” (B.S equivalent) in Earth Sciences, University of Poitiers, France