Some animals have their own evolutionary history or perspective. Some animals evolved from prehistoric animals such as the crocodiles, turtles, dogs, horses, birds and others. Evolution of animals is a mystery where scientists still look for the missing links to understand why appendages or body parts became useful or not to the evolution of the animal. Some animals developed from large animals to their small ancestors or some terrestrial animal to aquatic animal just like the whales. Scientists believed that the descendants of whales are those animals that walk on land.
Whales are not fishes. They are mammals. What are the characteristics of mammals that whales have? They have flippers resembling the forelimb of land animals. Their movement resembles of animals on the terrain. The movement of the spines is vertical or up and down. They still need air for breathing and lastly, giving birth to offsprings that are live ones. Whales are from the family of Cetaceans. It came from the Greek word “ketos,” meaning sea monster.
Scientists discovered different ancestors of the whales. That’s by starting from paleontologist Phil Gingerich who discovered a 52 million year old skull in Pakistan in the year 1978. They called it Pakicentus. It resembled the fossils of creodonts, a wolf like carnivore that lived between 60 and 37 million years ago in the early Eocene epoch. The key features of the Pakicentus were transitional between terrestrial mammals and earliest true whales were the bones and the most interesting is the ear region of the skull. It was modified for directional for hearing underwater.
Another believed descendant of the whale is the Ambulocentus or also known as the walking whale. It was amphibious animal. Its forelimbs were equipped with fingers and small hooves. The hind feet were adopted for swimming. It could get around effectively on land and could swim by pushing back its hind feet and undulating its tail just like otters of today.
The Rodhocentus was also considered as a descendant of whales. It had striking adaptations as to its aquatic lifestyle. Prehistoric whale was genuinely amphibians. They crawl up unto the land to forage food. The structure of its hipbones is not fused to its backbone. These bones provide great flexibility when swimming.
The Basilosaurus or the king lizard lived 40 million years ago. This animal was fully adapted to an aquatic environment. They swam the ancient seas by propelling their sturdy flippers, also long and flexible body. They are serpent like mammals. They had retained small, weak hind legs. These small hind legs are not are not for walking. These are appendages from its evolutionary past.
There are still a lot of ancestors and descendants of these giants of the seas. These are just some of them. Scientists say that they are not direct ancestors. They still say that there’s still a missing link to the evolutionary history of the whale.
http://www.pbs.org/wgbh/evolution/library/03/4/l_034_05.html
http://creation.com/refuting-evolution-chapter-5-whale-evolution
