What are some examples of megafauna and why are so many of these organisms extinct?
a) Mammoths and saber-toothed cats; Extinction due to climate change and human hunting
b) Dinosaurs and pterosaurs; Extinction due to asteroid impact and volcanic activity
c) Whales and elephants; Extinction due to habitat loss and pollution
d) Sharks and crocodiles; Extinction due to competition and disease