Fossils make scientists reconsider whale evolution theory

Previous scientists still think that we have fully understood the evolution of whales, but fossil records dating back to 36.4 million years have been discovered making scientists weigh repeat this.

Baleen whales are the largest mammals on Earth, including species such as blue whales or humpback whales. Researchers know that at one point, they had ancestors together with normal whales through traces of teeth and sperm.

However, to this day, the reason why they divide species is still a big question. Baleen whales are the first whales to use horns to filter food from water, instead of using teeth.

According to analyzes of fossil samples discovered on the southern coast of Peru in 2010, whale evolution will be filled, making them more complete and accurate.

The analysis found a new species of whale called Mystacodon selenensis , which is estimated to have lived two million years before the baleen whale, which is still thought to be a survival whale. at the earliest.

Remnant fossil records of a whale species date to 36.4 million years.(Photo: Olivier Lambert etal / Current Biology).

This provides researchers with clues about how the horned whale has a unique way of eating food. Leading researcher Olivier Lambert of the Royal Belgian Academy of Natural Sciences said: 'Species division between whales happened about 38 or 39 million years ago.'

'The whale fossil we just discovered is dated to 36.4 million years, so they probably lived 2 to 3 million years earlier. It means that this whale exists much earlier than other elephants'.

Cetacea, a set of whales or scientific nomenclature, is a set of creatures including modern whales, dolphins and sperm whales. Although they are called fish, they are actually mammals, meaning that they evolve like the way humans evolve.

About 55 million years ago, strange mammals looked more like dogs than dolphins. They live in two groups, one is Hippopotamus or Hippo , and the other is Humpback or Humpback Whale , and exist independently until today.

Today's ancestors of whales adapt to the water environment by gradually evolving, developing their noses and teeth to be able to catch fish and select nutrients in sediments. Over time, their limbs gradually develop to swim better and lose their ability to walk on the ground.

About 41 million years ago, a group of animals called Basilosauridae became the first whales to live in completely submerged environments, with the front legs flattened into fins, the hind legs smaller and the body already Can surf in the water.

They also have a small brain, but do not use too much for herd relationships. Over the next 10 million years, the whale has divided into two species, one that we call the Whale or Odontocet i, the other is the Baleen Whale or the Mysticeti .

However, not all mysticeti have a filtered horn, many of them with back spines or blue whales today still have teeth. Paleontologist Mark D. Uhen said: 'There are those with large teeth, serrated teeth and those without teeth'.

Today's horned whales are the most massive mammals on Earth.(Photo: Whit Welles Wwelles14).

23 million years ago, the whale's ancestors divided into the baleen whales as we know it today is still a mystery. No one knows exactly what conditions helped the baleen whales win in the species division, and more specifically why while the teeth are an important part retained by other whales, then the species of mysticeti is reduced.

Previously, the oldest known fossil whale dated to about 34 million years, belonging to a species called Llanocetus denticrenatus . This fossil is even larger than a modern dolphin, and features crossbreeding between toothed whales and baleen whales.

On the body of the fossil, there is still a small footprint left, which is a trace left after the limb is completely lost. Interestingly, the loss of later limb occurs almost simultaneously in the same two branches after they have divided the species.

Like today's whales, horned whales also use their jaws to eat small fish. They suck water from the ocean floor to look for small plankton to swallow.

Excavation and further study of fossil samples, along with the discovery of fossil samples in the middle of the species division, will help us gain more knowledge about whale evolution. , and why they develop into two branches like today.