When Whales Walked

PBS (2024)

Film Review

Aimed at ages 8-18, this documentary traces the fascinating evolutionary history of crocodiles, birds, whales and elephants.

Crocodiles

Because early crocodile fossils are relatively rare, scientists use changes in DNA structure to trace their evolutionary changes. By calculating degrees of difference between fossil and modern crocodile DNA, they can calculate the number of years separating modern animals from their ancestors.

The first crocodiles appeared 230 million years ago during the Triassic Age, when al the Earth’s continents were a single land mass called Pangia. Predating dinosaurs, crocodiles were land predators were land predators who walked on their hind legs. They subsequently evolved into a greyhound-like creature, walking on four legs and built for speed. Following a mass extinction event that wiped out most land and sea animals, massive volcanic activity broke Pangia apart. It also substantially increased volcanic activity, substantially increasing atmospheric carbon dioxide, leading to a mass extinction event.

Patagonia in South America was a great place for the surviving crocodiles, where they diversified into multiple species, including the 14 modern species.

Birds

Over 150 million years ago birds evolved from dinosaurs and still possess the same claws and tooth-like beak. However unlike birds, most dinosaurs lacked wish bones, the structure making flight possible.

Bird diversification expanded when crocodile evolution ended. There are more species (10,000) among birds than any other vertebrates, and they have colonized every habitat on earth.

In 1960 paleontologists finally discovered a dinosaur with a wishbone. It had feathers for warmth, clawed wings it used to kill prey and a short tail (like most birds). I

Whales

Bowhead whales can live up to 200 years. Blue whales are bigger than dinosaurs and have hearts the sized of small cars. Fossil whales are identified based on special ear bones in whales that help them detect sounds under water. The earliest whale fossil was a land mammal with webbed feet that that walking on four and spent time in the water. It took whales 10 million years for them to become fully aquatic.

Whales are extremely intelligent and live in a family social structure (parents, babies, grandparents, aunts and uncles) similar to humans. They communicate via low frequency vibrations that travel for miles and experience grief, anger and empathy.

Elephants

Sixty million years ago, elephant ancestors were the size of a rabbit and had incisors that gradually became tusks. Fifty-six million year-old ancestor fossils the size of a small dog have been discovered in Morocco.

The modern elephant species Elephants first appeared in Kenya’s Turkana Basin in Kenya 17 million years ago. These fossils are roughly 1/3 to 1/2 the size of modern elephants. Modern day elephants appeared seven million years ago.

Like humans, they also made numerous migrations (as family groups) out of Africa (fossil footprints have been in the desert near Abu Dhabi). Their first exodus was 18 millions years ago when all the continents were still connected. a million years ago some elephants made it all the way to Japan. The extinct elephant species known as woolly mammoths adapted to the cold of Siberia and North America.

Elephant fossils have been found on all continents except Austrailiaa,South America and Antarctica.