Question - What did the blue whale evolve from?

Answered by: Katherine Ross  |  Category: General  |  Last Updated: 16-06-2022  |  Views: 1251  |  Total Questions: 14

Hippos likely evolved from a group of anthracotheres about 15 million years ago, the first whales evolved over 50 million years ago, and the ancestor of both these groups was terrestrial. These first whales, such as Pakicetus, were typical land animals. They had long skulls and large carnivorous teeth. Both hippos and whales evolved from four-legged, even-toed, hoofed (ungulate) ancestors that lived on land about 50 million years ago. Unlike the hippo's ancestor, whale ancestors moved to the sea and evolved into swimming creatures over a period of about 8 million years. Marine Mammal Groups They evolved from a group of hoofed terrestrial ancestors within the order Artiodactyla more than 50 million years ago during the Eocene period. Their closest living relatives are the hippopotamuses, followed by the ruminants (deer, sheep, cows and their relatives). Blubber, blowholes and flukes are among the hallmarks of the roughly 80 species of cetaceans (whales, dolphins and porpoises) alive today. But, because they are mammals, we know that they must have evolved from land-dwelling ancestors. Scientists say the creatures were a "missing link" between primitive hoofed mammals and the whale family. The wolf-sized animals ran about on land 50 million years ago. Other newly found fossils add to the growing picture of how whales evolved from mammals that walked on land.

It lived in or near estuaries about 50 to 48 million years ago. Like Pakicetus, it spent time both in and out of water, but its large feet looked more like flippers than its ancestor's longer legs. It also used its tail for swimming.

Whales With Teeth Some whales have teeth, and all dolphins and porpoises have teeth. Approximately 65 different species of toothed whales exist. Toothed whales have one blowhole. These whales tend to be smaller in size than baleen whales.

The first human ancestors appeared between five million and seven million years ago, probably when some apelike creatures in Africa began to walk habitually on two legs. They were flaking crude stone tools by 2. 5 million years ago. Then some of them spread from Africa into Asia and Europe after two million years ago.

Whales belong to a group of sea-dwelling mammals called cetaceans, which also includes dolphins. Humans and other land-dwelling mammals need large pelvic bones to anchor their hind legs and walk around. The bones are therefore connected to the base of the spine and the tops of the leg bones.

In findings to be published this week in the Proceedings of the National Academy of Sciences, scientists say the gradual shrinkage of the whales' hind limbs over 15 million years was the result of slowly accumulated genetic changes that influenced the size of the limbs and that these changes happened sometime late in

Marine mammals are found in marine ecosystems around the globe. Marine mammals are classified into four different taxonomic groups: cetaceans (whales, dolphins, and porpoises), pinnipeds (seals, sea lions, and walruses), sirenians (manatees and dugongs), and marine fissipeds (polar bears and sea otters).

Whales Returned to the Sea. Vertebrates evolved in the sea and eventually moved onto land. The ancestors of whales later returned to the sea, taking advantage of its rich food supplies. As early whales adapted to their new marine surroundings, a diversity of species evolved.

The first oceanic dolphins such as kentriodonts, evolved in the late Oligocene and diversified greatly during the mid-Miocene. The first fossil cetaceans near shallow seas (where porpoises inhabit) were found around the North Pacific; species like Semirostrum were found along California (in what were then estuaries).

Fossil remains show dolphins and whales were four-footed land animals about 50 million years ago and share the same common ancestor as hippos and deer. Scientists believe they later transitioned to an aquatic lifestyle and their hind limbs disappeared.

All cetaceans are carnivores and do not consume plants or algae as food. The large baleen whales eat schooling organisms that range in length from minute drifting mollusks, copepods (1 cm or less), krill (1–5 cm), and small fish and squid up to about 40 cm.