Coccoliths formed the chalk beds that name this period of time. The Alvarez hypothesis uses shocked quartz and iridium concentration to explain how this period of time ended. Bees aided the spread of 
Coccoliths formed the chalk beds that name this period of time. The Alvarez hypothesis uses shocked quartz and iridium concentration to explain how this period of time ended. Bees aided the spread of (*) flowering plants which first appeared in this period, whose geologic strata ends at the K-T boundary. Placental species coexisted with dinosaurs during, for 10 points, what last period of the Mesozoic era whose dinosaur species included T-rex?
Coccoliths formed the chalk beds that name this period of time.
Cretaceous Period