Dorsal vertebra of platecarpus, a cretaceous. Mosasaur from the Niobrara Chalk of Kansas etc.
Licence: Attribution 4.0 International (CC BY 4.0)
Credit: Dorsal vertebra of platecarpus, a cretaceous. Mosasaur from the Niobrara Chalk of Kansas etc. Wellcome Collection. Source: Wellcome Collection.