why did whales evolve

How did the programs within those cells along with the execution files to run those cells evolve. Find out in an article I have written.At this particular time, the land was becoming more populated, and so the animals that were present needed new food sources.The ocean was rich in the required nutrients, and whales were then separated into two new groups, baleen whales and toothed whales.Scientists agree that moving back into the water allowed the whales of today to reach the colossal sizes that they grow to by removing the restraints of gravity.The low gravity of water causes less strain to the bones. He had found vertebrae and other fragments while blasting on his property and also sent off a few samples to the Philadelphia society.

With this new context, however, the stubby, seal-like form for,The earliest known archaeocetes were creatures like the 53-million-year-old,Living at about the same time as the remingtonocetids was another group of even more aquatically adapted whales, the protocetids. Given that both Creagh and Bry said they had seen intact vertebral columns in excess of 100 feet in length, the living creature must have been one of the largest vertebrates to have ever lived. But, because they are mammals, we know that they must have evolved from land-dwelling ancestors.About 375 million years ago, the first tetrapods—vertebrates with arms and legs—pushed themselves out of the swamps and began to live on land. The skull is very small, indicating the recent one from being a land mammal, although it does have an ear bone adapted for hearing underwater.Protocetus from 50 million years ago has adapted further. Cetotheriidae had about 50 species of whales at its most successful period.Many of this family made several adaptations, including a longer skull and baleen in its mouth. These land-based mammals are believed to be hoofed mammals, sharing a common ancestry with even-toed ungulates such as the cow and the deer.Mesonychidae was a family of hoofed mammals that lived in Asia, Europe, and North America. 1 In another place, the FL DoE have, quite correctly, emphasized the importance of students understanding that a hypothesis must be capable of being tested. These two coexisted in the oceans for approximately 7 million years. The evolutionary story of the whale is one that has confused scientists for years.It had been difficult to understand why an animal that had evolved to live in a terrestrial manner would then head back into the water, but it seems that food was the main motivator.

The new teeth were all the same, indicating the move to homodont teeth.Changes to the skull were needed to accommodate the melon on top of their head in front of the braincase. From feeding on fish, they then evolved to an amphibious nature.These earliest amphibious Mesonychidae would have fur and been otter-like in moving around the water using all four limbs.The tail would have become flat from beating the water, and this would have led to the regression of the hind-limbs.Whales started their journey as all other organisms have, as single-celled bacteria.An evolutionary picture of the whales can be broken down as follows:Modern-day whales are believed to have moved into the oceans around the Tethys Sea, now the Mediterranean Sea and Asia.Fossils recovered show an animal called Archaeoceti, thought to be the first sub-order of cetaceans, existed in the estuaries of the Tethys Sea.Archaeoceti originally had four limbs but adapted to an aquatic way of life.There were many adaptations to living in the sea that these mammals did not have while on land. As strange as modern whales are, their fossil predecessors were even stranger.Pioneers who cleared land in Alabama and Arkansas frequently found enormous round bones. These earliest cetaceans were not like the whales we know today, and only recently have paleontologists been able to recognize them.For more than a century, our knowledge of the whale fossil record was so sparse that no one could be certain what the ancestors of whales looked like. 1846. Though these creatures, such as.By the time the first mammals evolved 200 million years ago, however, dinosaurs were the dominant vertebrates.

The nostrils located at the front moved to the tops of their heads, forming the blowholes we now know.To be able to find and catch prey, the jaws and teeth had to change. Some of these mammals had adapted to eating fish, and it is believed that they would feed around the shallow edges of water around the Tethys Sea.

Even in so extreme a case as this, if the supply of insects were constant, and if better adapted competitors did not already exist in the country, I can see no difficulty in a race of bears being rendered, by natural selection, more and more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale.Darwin was widely ridiculed for this passage. North American Nature is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. Richard Harlan reviewed the fossils, which were unlike any he had seen before. The semi-aquatic otters and beavers, he claimed, were better alternative models for the earliest terrestrial ancestors of whales. However, their skulls particularly in the ear region, which is surrounded by a bony wall strongly resemble those of living whales and are unlike those of any other mammal. However, it could also be that the rocks needed to find later specimens of Archaeocetes have not been found in the oceans yet.Most fossils are found in shallow waters, but it could be that Archaeocetes evolved to swim in deeper waters.Kekenodon is the last fossil of Archaeocetes from about 30 million years ago.Approximately 25 million years ago, at the end of the Oligocene era, many toothed whales lived in the oceans across the world.

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