Evolution Unveiled

All living things on earth are related and evolved from a common ancestor, and the evolution of living things is powered by natural processes that can be studied and understood.

Comparative anatomy is the study of differences and similarities between living things. It tells us that whales, despite living in water and resembling fish from a distance, are actually more similar to land mammals in many ways.

Whales have placentas and give live birth, feed milk to their young, are warm-blooded, do not have gills, instead breathe air with 2 fully developed lungs, have arm, wrist, hand, and finger bones inside their front flippers, have hair, and do not have noses like mammals do.

Blowholes are the nasal openings on the tops of the heads of whales. They relate to the evolution of whales because they are actually highly modified mammal noses.

Embryology is the study of how creatures develop before being born or hatching from an egg. It tells us that whales and dolphins share some common features in their embryonic development with land mammals, including arm and leg buds.

The fossil record is the record of past life as preserved in rocks and other materials. It provides evidence for the evolution of whales by showing us intermediate species, such as basilosaurid whales, that have features of both land mammals and modern whales.

The two species of extinct basilosaurid whales mentioned in the text are known from multiple well-preserved skeletons and lived side by side roughly 34 to 40 million years ago. They are significant because their nasal opening is not on the top of the head like modern whales or at the end of the snout like most land mammals, but instead sits right in the middle, making them an intermediate species.