Dolphin Evolution

dolphin evolutionThe process of evolution can be very slow, and it allows living creatures to develop an anatomy that is structured for them to thrive. Dolphins have ancestral connections to terrestrial mammals which is a fact that many people don’t know about. Plenty of the research that has been conducted indicates that this is with the Artiodactyl order. It is believed that the ancestors of dolphins that we know and love today entered the water about 50 million years ago!

There are many telling signs that the dolphin is related to terrestrial origins. The fact that they need to come to the surface of the water to get air is the most dominant factor. Researchers have carefully examined the bones of the fins for dolphins. What they find is that they strongly resemble the limbs of many animals that live on land. Dolphins have spines that move vertically, and this is a characteristic mainly found in animals that are able to run on land. When you look at the movements of fish, their spines move horizontally.

The size and the shape of the skull has changed over time too. It has become larger which is an indication that the development of the fat pad in the lower jaw emerged. It extends to the middle ear and this helps dolphins to be able to hear as well as to use the process of echolocation.It is believed that during the early Miocene period, the use of echolocation was developed in the form that dolphins rely on it today. The early dolphins were smaller and believed to have consumed small fish as well as various organisms in the water.

The older theory is that the evolution was of whales and they came from ancestors of hoofed land animals that were very similar to wolves and even toed ungulates. The animals had teeth that were triangular, similar to those of whales. However, the new evidence draws away from that theory and offers information that the whales would be closer related to hippopotamus and their ancestors. Those that argue this point out that the ancestors of hippopotamus hasn’t been in the fossil record until more than 1 million years after the first known ancestor of the whale, Pakicetus.

The most recent information about the Pakicetus, shows us that whales aren’t ancestors of mesonychids. Instead, they are artiodactyls and it is believed when they split from the mseonychids is when the process of living in the water started to occur. What is interesting though is that unlike many other mammals, they didn’t change to being herbivores. Instead, they continued to be carnivorous in the water as they would have been on land.

What was once outwardly seen of the whale hind parts are now smaller and they are also internalized. However, sometimes there is the development of mini legs called atavism and that is believed to be the result of a genetic code that will call for longer extremities to form. Another change was that the nasal openings moved from the end of the snout to the top of the skull area. This is what is referred to as nasal drift.

Those nostrils later evolved into blowholes so that they can get to the surface of the water, take in air, and then be submerged again with ease. The movement of the ears closer to the eyes is also part of the evolution process. Very interesting changes over time to help them survive in their environment in the water only and not on land as before due to ancestral links.

There are plenty of questions that still linger about the evolution process for dolphins. The good news though is that some of the evidence that has been located gives a better idea of what really occurred. It has also helped to add some support to various theories that still have to be tested and proven. Some of the fossil remains found in Pakistan in the 1970s identify some of the different changes that took place for the anatomy of the dolphin.

The current process of evolution could be slowly changing the limbs of the dolphin. Some embryos have been spotted with hind limb buds that will develop close to the base of the fluke which is the tail. They are about 1 inch long. The modern body of the dolphin does show two small pelvic bones that are rod shaped. Yet these limbs aren’t really shown on the outside. However, in 2006 a Bottlenose Dolphin was found in Japan that featured these small fins on each side of the body.

While a great deal more of research is necessary, it is possible that what is being witnessed is the slow movement of evolution for the body of dolphins taking place. Only time will tell if that is what occurs and if these hind limb buds start to be visually present on future generations of offspring.

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