Cretaceous–Paleogene boundary Cretaceous–Paleogene boundary The Cretaceous–Paleogene (K–Pg) boundary, formerly known as the Cretaceous–Tertiary (K-T) boundary, is a geological signature, usually a thin band of rock. "K", the first letter of the German word "Kreide" (chalk), is the traditional abbreviation for the Cretaceous Period and "Pg" is the abbreviation for the Paleogene Period. The K–Pg boundary marks the end of the Cretaceous Period, the last period of the Mesozoic Era, and marks the beginning of the Paleogene Period, the first period of the Cenozoic Era. Its age is usually estimated at around 66 Ma (million years ago), with radiometric dating yielding a more
The Magic School Bus In the Time of the Dinosaurs periods (Triassic, Jurassic, and Cretaceous) were seen in the book; only the book focuses with all of the time periods. This is because it was due to time constraints; time constraints in order for the episode to be up to 30 minutes (30 minutes like all episodes in the TV series). In this episode, the kids visit Ms. Frizzle's old friend, Dr. Carmina Skeledon at a dinosaur dig, as opposed to Jeff in the book. Dr. Skeledon lets Arnold see a fossilized dinosaur egg that Ms. Frizzle finds as the kids are leaving, and he still has it when they