A (period rock) can be cretaceous.Logical formLearned from3 sentences. (Mass extinctions) may occur at an end of a cretaceous period.Logical formLearned from3 sentences. A cretaceous period may include a demise of dinosaurs.Logical formLearned from3 sentences. Flowers may be preserved from a cretaceous period.Logical formLearned from3 sentences. Elasmosaurids can be cretaceous.Logical formLearned from3 sentences. Champsosaurs can be cretaceous.Logical formLearned from3 sentences. A portion can be cretaceous.Logical formLearned from3 sentences. Nannofossils can be cretaceous.Logical formLearned from3 sentences. Microfossils can be cretaceous.Logical formLearned from3 sentences. A superchron can be cretaceous.Logical formLearned from3 sentences. A layer can be cretaceous.Logical formLearned from3 sentences. A family can be cretaceous.Logical formLearned from3 sentences. (Climate changes) may be culminated in an end of a cretaceous period.Logical formLearned from3 sentences. A mass extinction can be at an end of a cretaceous period.Logical formLearned from3 sentences. An aquifer can be cretaceous.Logical formLearned from3 sentences.