Biology · Evolution · NEET
About 65 million years ago (65 mya). NCERT clearly states dinosaurs "suddenly disappeared from the earth" about 65 mya. This exact number is directly asked in NEET matching questions, so remember it as a fixed value.
NCERT says the TRUE reason is NOT known. It gives two ideas: (1) some say climatic changes killed them, (2) some say most of them evolved into birds. It ends with "the truth may live in between." For NEET, do not pick only one cause as certain - the safe answer is that the reason is unknown/uncertain.
Dinosaurs were REPTILES - specifically the land reptiles. NCERT writes "The land reptiles were, of course, the dinosaurs." They are not a separate group above reptiles. This is a common trap.
Dinosaurs were LAND reptiles. Ichthyosaurs were fish-LIKE reptiles that went back into water, evolving about 200 mya. Both are reptiles, but Ichthyosaurs are aquatic (fish-like) while dinosaurs are land forms. Do not confuse the two.
NCERT notes that "small sized reptiles of that era still exist today" and that some say most dinosaurs evolved into birds. So a line of them may survive today as birds, and small reptiles of that era still exist. But the giant dinosaurs disappeared.
Tyrannosaurus rex was the biggest - about 20 feet in height with huge, fearsome, dagger-like teeth. Remember "T. rex = 20 feet + dagger teeth" for one-liner NEET facts.
MAMMALS took over. NCERT says "When reptiles came down mammals took over this earth." The first mammals were shrew-like, small, viviparous (protected young inside the body), and more intelligent at sensing danger.
Match List I with List II with respect to chronology of evolution of life forms List-I A. About 65 mya B. About 500 mya C. About 350 mya D. About 320 mya List-II (I) Jawless fish probably evolved (II) The dinosaurs suddenly disappeared from the earth (III) Seaweeds and few plants probably existed (IV) Invertebrates were formed and became active Choose the correct answer from the options given below:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Yes. The date "about 65 mya" for dinosaur extinction is directly asked in matching/chronology questions (for example NEET 2026). Learn it as a fixed one-liner along with the geological timeline.
NCERT mentions this as one idea: "some say most of them evolved into birds." It is presented as a possibility, not a confirmed fact, so treat it as one of the given reasons, not a certainty.
NCERT says "We do not know the true reason." It lists climatic change and evolution into birds as two ideas and says "the truth may live in between." So the correct exam stance is that the reason is uncertain.
No. Ichthyosaurs were fish-like reptiles that went back into water about 200 mya. Dinosaurs were land reptiles. Both are reptiles, but they are different forms.
