Answer:
The extinction of a large number of species within a relatively short period of geological time.
Answer: molecule
Explanation: common knowledge
Dinosaur fossils had been known for centuries as "dragon bones" or the remains of giants, but it wasn't until Dean William Buckland of Oxford, England described the carnivorous "lizard" Megalosaurus<span> (in 1824) that they were formally studied as an extinct group of giant reptiles</span>