Evolution Proj - History of Whales (Cetacea)

Timeline created by robertandshane
  • Period:
    Jan 1, 900
    to

    Whales!

  • Aug 25, 950

    Phylogeny

    Phylogeny
    This phylogenic tree shows the connection between whales and their ancestors. This branch of the phylogenic tree encompasses the order of Cetacea, which have evolved into the modern day marine mammals known as whales.
  • Jan 1, 1000

    Indohyus appears

    Indohyus appears
    Indohyus are believed to have lived around 48 million years ago, around Asia. They are commonly referred to as the "missing link" for whales. This organism was the first member of the Cetacea order to develop whale-like qualities, such as a thick layer of skin and dense bones.
  • Jan 1, 1000

    Pakicetus (depending on source, aka Pakicetid)

    Pakicetus (depending on source, aka Pakicetid)
    Whales are from the order of Cetacea, meaning "whale" or "huge fish monster" in Greek. This order has evolved over time to include marine mammals, including whales, dolphins, and porpoises. The Pakicetus is one of the early members of this order, They are hoofed land mammals found near Pakistan, hence their name. They are believed to be one of the earliest decesndants of whales.
  • Mar 13, 1100

    Ambulocetus

    Ambulocetus
    Ambulocetus was the next step in the phylogenic tree. Many fossils were found in Pakistan, 1993 by Johannes Thewissen. This organism was like its predessors, except it could walk AND swim. The body has becomed more sleek and can now swim. This was the first step in where whales entered the water and their bodies changed accordingly. This allowed for their survival as a species who could choose where the best food would be. It was clear that the ocean had more opportunities for survival and food.
  • Aug 24, 1250

    Rodhocetus

    Rodhocetus
    The Rodhocetus is a continuation of this order, appearing about 50 million years ago. Their legs continue to disappear. They also began to enter salt water The swimming style resembles otters more than whales. However, this animal is linked to the whale as evident from its hindleg bones which modern day whales have.
  • Feb 28, 1500

    Protocetus

    Protocetus
    The protocetus appeared about 45 million years ago around modern Egypt. It was more developed than its predessors, in that it had smaller back fins. The bones in the tail resemble the tail flukes of modern whales. Lastly, the protocetus (its name referring to how it was truly the first, or proto, member of the modern cetacea whale group) also did not have a true blowhole. This creature had a unique ear structure that allowed it to hear, though not use echolocation quite like modern day whales.
  • Basilosaurus

    Basilosaurus
    The Basilosaurus, meaning king lizard in latin, appeared about 40 million years ago around the southeastern United States region. This vertebrae resembles modern day whales for its small hind flippers, therefore it was completely bound to the water. Unlike whales, however, it was restricted to the shallower parts of oceans. However, it was not found in freshwater climates, indicating how whales successfully moved to the ocean for more space (as it grew) and more food.
  • Janjucetus

    Janjucetus
    Jancjucetus was part of a major split (the other being Squaladon) of the whale phylogenic tree that happened around 33 million years ago. This organism would precede many baleen whales today, named for their baleen teeth. The teeth, made of keratin, are unique in that krill is brought into the mouth in large quantities, and then the teeth filter out the water, leaving only krill and other edible organisms. This was a remarkable milestone in the whale timeline.
  • Squalodron

    Squalodron
    Around the same time as Janjucetus, Squaladrons appeared. They differ from Janjucetus whales because they were a predessor to the tooth-whales, whereas the janjuceti were the ancestors of Baleen whales, with their baleen teeth. Their necks also began to grow shorter.
  • Squalodron continued

    Squalodron continued
    (teeth fossils are shown in the picture). Jean-Pierre Sylvestre de Grateloup discovered this organism but incorrectly labeled it as part of the Iguanodontia family,a group of herbivore dinosaurs. They were later classified by Charles Darwin as "undoubtedly cetacean".
  • Cetotherium

    Cetotherium
    The Cetotherium was the last major genus of organisms prior to the baleen whales. They were smaller than modern whales, but they had many similar features. Their body structure, baleen teeth, and bone set-up resembled that of modern day whales. They were hunted by great white sharks and megaladons (the latter being extremely large sharks).
  • Whales!

    Whales!
    Whale Timeline for more information!All these organisms have allowed the evolution of whales into what they appear today. There are two main types of whales: toothed and baleen. The tooth ones (including beluga and killer whales) orginate from the squalodron, while the baleen ones (including humpback and blue whales) originate from janjucetus. This split was a major event in history. Whales of modern day biology are the largest recorded animals to have ever existed. They resemble their past organisms through their hind bones.
  • Whales! continued

    Whales! continued
    Whales utilize echolocation, with their help of the melon, an organ that was not present before. This was a significant difference between whales and their predecessors. This allowed whales to grow in size. However, recently they have become the target of whaling. Their population has decreased since. With the help of many countries around the world, the population of whales have leveled out, and hopefully will begin to increase.
  • Jared was born

    Jared was born
    Jare-bears kill whales off the coast of the Guadalupe-Hidalgo Bosnia and Herzegovina Czechoslovakia-Rhineland-Kyrgyzstan border! They are a vicious family of bears that have caused the extinction of many whales, dolphins, porpoises, and innocent Biology students of the Connery-class phyla. Watch as they attack this innocent student with its hug of death!