Question

Mammals have about 5000 species today, and date to about 200 million years old (though major diversification of mammals happened about 65 million years ago). Compared to beetles, which have 400,000 species they are a small taxon. Compared to dragonflies, which also have about 5000 species but are 400 million years old, they are a young taxon. Are mammals successful in terms of evolution? Why or why not? Defend your answer.

Answer 1

Biological success would be an animal's ability to successfully survive and reproduce. The purpose of reproducing is to pass on its genes to the next generation. Mammals evolutionary success relied on our ancestors growing very tiny. When mammals first started popping up around 200 million years ago, our planet was still dominated by dinosaurs. So for the following 150-ish million years, mammals literally and figuratively kept a low profile. While dinosaurs were growing bigger, mammals shrank in size. Mammals stand out among all other vertebrates on the planet in that they have a single bone bearing teeth for their lower jaw. Everyone else has more complex lower jaws, formed from no fewer than five bones linked together, the team explains.
As mammals evolved, most of these bones shrank in size and became more simplified. The new jaw retained a single bone, and the others moved higher in the skull, into the inner ear. They now help us hear.The mammals are also the most successful animals on Earth because they can maintain a constant body temperature with high range of tolerance whether in Antarctica or in the Sahara desert.