Foetus of a Triassic ichthyosaur

Ichthyosaurs were a group of Mesozoic marine reptiles highly adapted to life in the ocean. One of their most important adaptations was live birth, which eliminated the need to return to land to reproduce. Although embryos and foetuses of Jurassic and Cretaceous ichthyosaurs are well documented, the reproductive biology of Triassic forms remains poorly understood. A new study describes a foetus of Besanosaurus leptorhynchus from the Middle Triassic of Italy (Monte San Giorgio), providing new insights into the reproductive biology of early ichthyosaurs.

Figure: Reconstruction of adult and newborn individuals of the Middle Triassic ichthyosaur Besanosaurus leptorhynchus from Italy (artist: Fabio Manucci).