How did climatic and oceanographic conditions change a few million years before the end of the Cretaceous Period? What were the consequences for the reef-building rudists?

A few million years before the end of the Cretaceous Period, climatic and oceanographic conditions experienced further changes, including more pronounced fluctuations in sea levels and alterations in oceanic circulation and nutrient availability. These changes resulted in consequences for the reef-building rudists, a group of bivalve mollusks. The decrease in suitable habitats due to sea-level fluctuations, along with changes in oceanic circulation and nutrient availability, led to a decline in the overall distribution and abundance of rudists. These conditions likely contributed to the extinction of rudists at the end of the Cretaceous Period, in addition to other factors such as volcanic activity, asteroid impacts, and major climate changes.