The Jura-Cretaceous boundary marks the transition between the Jurassic and Cretaceous periods, approximately 145 million years ago. This boundary is characterized by significant changes in faunal assemblages and global climate. Understanding this boundary is important for studying the evolution of life, paleoclimate, and the geological history of the Mesozoic era.
Reference: Ogg, J. G., & Hinnov, L. A. (2012). “Jurassic.” In: Gradstein, F. M., Ogg, J. G., Schmitz, M., & Ogg, G. (Eds.), The Geologic Time Scale 2012. Elsevier, pp. 731-791.