How many years has the whale evolved, the evolution of the whale and the evolution of man

The evolution route of whales is roughly as follows: from terrestrial bucky whales, through amphibious terrestrial whales, to basic aquatic but still developed limbs of proto-whales, to fully aquatic spear-toothed whales and dragon king whales with greatly degraded hind limbs, and finally from spear-toothed whales to modern toothed whales and baleen whales, which have experienced a total history of about 50 million years.

Early ape-man. 2 million years ago to 1.75 million years ago Homo sapiens (Oduvai Gorge, Tanzania) Brain volume 637 ml, walking upright, thumb and other four fingers can be held together, but the movements are not precise. Gravel can be beaten into choppers, and this stone tool culture is called the Auduvé culture. Homo sapiens live in complete dependence on the natural world.

Late ape-man. 1.75 million years ago to 20 300,000 years ago Yuanmou people (Shangnabang Village, Yuanmou, Yunnan Province, China).

Beijing Ape Man (Zhoukou store, Fangshan District, Beijing, China).

Javanese (West Java, Indonesia) has a brain size of 1 059 ml, can walk upright on two legs like modern humans, has more dexterous hands, and can build a variety of stone tools. It can manufacture many types of stone tools, the processing is exquisite, the stone tool culture has made great progress, can use fire, live in a group of dozens of people, and have a certain ability to cope with natural changes.

Early Homo sapiens. 20 300,000 to 50,000 years ago Maba people (Maba Township, Qujiang County, Guangdong, China).

Neanderthal (Neanderthal Valley, Germany) The brain volume is 1 350 ml, which is close to the brain size of modern humans, and some primitive features are retained in the constitution (protruding mouth, developed brow ridge, etc.). Able to produce tools, can hunt large beasts, master the technology of artificial fire, and further improve the ability to conquer nature.

Late Homo sapiens. 50,000 to 10,000 years ago Cave Man (Zhoukoudian, Fangshan District, Beijing, China).

Cro-Magnon (Cro-Magnon Village, France) The brain size is basically the same as that of modern humans, reaching 1 400 ml, and the body shape is similar to that of modern humans. It can make intricate tools such as stone, bone and horn tools, make elaborate and unique works of art and ornaments, sew clothes, build tents, and conduct large-scale hunting activities. May begin to live in a matrilineal clan society.

Whales were originally thought to be animals that walked on all fours on land, but later "went to the sea" due to foraging problems, and practiced monogamy, like "bigfin whales" usually live alone, while other whales also live in groups. Their gestation period is generally about 12 months, one litter and one son, and the lactation period of young whales is 10 months, and the lifespan is about 60 to 70 years.

The ancestor of cetaceans is most likely a terrestrial ungulate from North America, Europe and Asia, the meso-clawed beast family (Mesonychidae). The members of the mesoclawed beast range from petite dogs to tall bears, but many animals have evolved from small to large, so it is possible that cetaceans evolved from small mesoclawes.

It is speculated that these small number of teeth, and that the meso-clawed beast, which fished in shallow waters, gradually changed to an amphibious lifestyle, and then evolved into today's various cetaceans and dolphins over a long evolutionary process.

The earliest cetaceans to appear were the archaeocetes, protocetidae.

Protocetaceans all appeared 50 million years ago, and the fossils are distributed in Asia, Africa and North America. Scientists know more about the pakicetus, a fossil creature that lived between 53 million and 50 million years ago, and is an animal with fumaroles (nostrils) that have moved backwards, have long and narrow ventricles, and still have hind limbs. Fossil evidence found in contemporaneous Indian rock formations also suggests an unimaginably high degree of ecological heterogeneity among early cetaceans.

The more advanced suborder of ancient cetaceans is the basilosauridae, which was once recognized as a reptile. The animals of this family lived about 45 million to 38 million years ago, and although they were first discovered by American geologists in Louisiana, similar fossils have been widely found in New Zealand and even Antarctica. The discovery shows that the suborder Paleocetae spread to southern waters 40 million years ago.

Another clade of the more advanced Paleocetine suborder is the dorudontinae, which contains at least six animal species, and they have a narrow palate that may be filter-feeding; Or, like living whales, they can quickly catch fish, squid and birds.

(so people mistake it for a fish) and adapted to life in the ocean.

The whale is not a real fish, but a mammal, this animal and our common cattle, horses, sheep, pigs, dogs, etc. have 4 legs and tails, etc., and there is not much difference in size, but this animal chose to enter the marine life for some reason, and gradually evolved into an almost completely fish-like body shape.

Paleontologists have a close relationship between cetacans and ungulates through biogenetics, and fossil evidence records also support the evolution of cetaceans from artiodactyls, and it is now generally accepted that the ancestor of cetaceans is most likely a terrestrial ungulate, the mesoclaw, which lived 58 million years ago.

The early mesoclaw, about the size of today's sheep and wolves, was a carnivorous mammal that may have preferred to fish in shallow waters for a while, before gradually transitioning to an amphibious lifestyle.

The earliest cetaceans to appear are the ancient whale suborder Protocetacedae, which appeared 50 million years ago, and biologists know more about the Pakistani ancient whale (also known as the Pakistan whale) found in present-day Pakistan, this animal has begun to take on the form of a whale, the head fumarole (nostrils) have moved to the rear, has a long and narrow ventricle, and still retains some mammalian characteristics, such as still having hind limbs. Later, there was the family of cetaceans, which lived about 38 million to 45 million years ago, and then there was the subfamily of stiff-toothed whales, which had a narrow upper jaw, which may be filter-feeding, and then the ancient cetale suborder gradually went extinct, but the baleen whale suborder and the toothed whale suborder have evolved, and these two groups have derived nearly 100 species in 17 families so far.

The evolution of whales.

The ancestry of whales is an issue that has been debated for many years. Although we know that whales evolved from terrestrial quadruped mammals, we do not know which animals evolved into whales, nor do we understand why this animal abandoned land and returned to the ocean. Based on the striking similarity of the teeth, some paleontologists believe that whales evolved as a wolf-like mammal.

Scientists, on the other hand, use DNA analysis to suggest that whales evolved from a group of animals, including hippos, camels, and pigs. Recently, fossilized whale bones from about 50 million years ago were discovered in Pakistan, but instead of resolving the evolutionary debate, the discovery has only deepened the mystery as the fossils do not support any of these theories.

The evolutionary process of cetaceans is the opposite of the evolutionary process of ordinary life, it evolved from terrestrial to aquatic, and after several transitional types, it finally formed the whale as we know it now. The general process is as follows:

1. Bucky Whale: It was one of the few mammals that ventured into the water at the time. The Bucky whale had endophytic ears, a rarity in the biological world at the time, and this unique physiological structure is reflected in today's cetaceans or their fossils, leading scientists to speculate that it is the ancestor of cetaceans.

2. Walking whales: When the bucky whale evolved into a walking whale, it was already able to adapt to both land and water environments, and scientists guessed that it would not move very fast in the water based on its fossils. Its hind limbs are more suitable for swimming, and it can swing its back like an otter and cetaceans.

3. Protowhale: By the time it evolved into a protowhale, it was able to live completely in the water, but it would still "patronize" land, and scientists made this guess by restoring its strong hind limbs through fossils.

4. Speartooth Whale: The speartooth whale has lived completely in the water, and fin-like organs have appeared on the tail to help it move forward in the water, but at the same time still retain the hind leg-like structure of its ancestors. Eventually, after hundreds of millions of years of evolution, the cetaceans we see today were formed.