The long bone histology of Ceresiosaurus (Sauropterygia, Reptilia) in comparison to other eosauropterygians from the Middle Triassic of Monte San Giorgio (Switzerland/Italy)

A comparative histological analysis of the long bones of Ceresiosaurus, a secondarily marine reptile from the Middle Triassic of Monte San Giorgio (Switzerland/Italy), reveals distinct interspecific differences that correlate with proposed locomotion types. Both species, Ceresiosaurus calcagnii and C. lanzi, exhibit cyclical bone growth with lamellar to parallel-fibred matrices and low to moderate vascularization, but differ in the distribution of bone matrices and vascular patterns. C. calcagnii's pachyosteosclerotic bones resemble those of the younger Neusticosaurus edwardsii, while C. lanzi shows similarities to young Nothosaurus. These findings suggest divergent growth strategies linked to distinct ecological niches within a restricted lagoonal environment, supporting earlier morphological studies that ascribed different locomotion behaviors to each species.

Hugi, J. (2011). The long bone histology of Ceresiosaurus (Sauropterygia, Reptilia) in comparison to other eosauropterygians from the Middle Triassic of Monte San Giorgio (Switzerland/Italy). Swiss Journal of Palaeontology, 130(2). https://doi.org/10.1007/s13358-011-0023-6