Prehistoric Cetaceans You might not know it by looking at them but hippos are the closest relative to whales and both whales and hippos likely share a common ancestor millions of years ago There were a lot of evolutionary steps in the history of whales but one thing we can learn about them from their hippo relatives and some of the other species that came before them is that whale ancestors probably had legs and walked on land It might seem crazy to think of whales with legs but these ancestors were likely able to live both on land and in the water much like modern day hippos do so they would have breathed air and been able to walk and swim Eventually they evolved from having legs to having fins but they kept the ability to breathe air Their front legs eventually morphed into flippers their tails elongated and their back legs disappeared entirely allowing them to maneuver in the water more efficiently We know this because the hip bones of some modern whales show evidence that their ancestors had hind legs In this section we’ll look at some of the prehistoric ancestors of modern day whales and the important traits they developed and passed on that helped them to move from land to sea as well as some prehistoric cetaceans that looked similar to modern dolphins day porpoises and whales 10
PAKICETUS AMBULOCETUS PROTOCETUS Pakicetus inachus AMBULOCETUS NATANS PROTOCETUS ATAVUS WHEN About 56 to 40 million years ago WHERE Modern Pakistan SIZE 100 pounds 45 kg roughly the size of a wolf LOOK FOR A rodentlike animal with a long tail and a long snout PREHISTORIC PROFILE Pakicetus looks like a land animal but it has a lot more in common with modern whales and hippos than you might think Pakicetus had an ear bone that was similar to the unique ear bone in modern whales as well as an anklebone associated with hoofed animals making it possible that Pakicetus was a distant ancestor to both whales and hippos This carnivorous four legged animal is thought to have eaten both meat and fish which makes it likely that it was able to navigate both land and sea WHEN About 49 million years ago WHERE Modern Pakistan LENGTH 9 3 4 feet 3 meters LOOK FOR Webbed feet and a long snout full of teeth PREHISTORIC PROFILE It’s not hard to picture Ambulocetus in the water with its crocodile like snout Although Ambulocetus still had legs its feet had flipper like qualities to them including webbed hind feet To move around on land this heavy creature may have waddled or used its front legs to pull it along similar to how modern sea lions move Studies of Ambulocetus skulls helped scientists to understand that this creature was likely able to swallow food underwater and it had teeth that were similar in shape to other cetacean ancestors By studying the chemicals in their teeth scientists were able to discover that they likely fed in both freshwater and saltwater 11 WHEN 48 6 to 40 4 million years ago WHERE Modern Egypt LENGTH About 8 feet 1 2 2 meters LOOK FOR Beak like snout front flippers with webbed toes small back flippers and a back ridge PREHISTORIC PROFILE Protocetus atavus means first whale an accurate title for this early cetacean With a streamlined whalelike body and a fluke tail Protocetus shares many attributes found in modern day whales Protocetus was discovered near modern day Cairo Egypt with the first description of this early cetacean completed in 1904 Have you ever tried listening to something underwater Scientists believe that Protocetus had a set of ears that could hear underwater as well as a good sense of smell but unlike many modern whales they were unable to echolocate
BASILOSAURUS CORONODON AETIOCETUS BASILOSAURUS ISIS WHEN About 37 million years ago WHERE Modern Egypt Jordan and Morocco LENGTH 59 to 65 1 2 feet 18 to 20 meters LOOK FOR An incredibly long tail compared to the rest of its body PREHISTORIC PROFILE You definitely wouldn’t want to encounter a Basilosaurus in the ancient ocean Scientists think Basilosaurus was likely a predator and its jaws and teeth had a very powerful bite Evidence shows that they fed on fish and sharks and Basilosaurus bite marks on fossil Dorudon atrox skulls suggest that Dorudon may also have been prey to Basilosaurus These massive animals may have been some of the first fully aquatic mammals There are two different species of Basilosaurus and numerous fossils found across northern Africa suggest that it likely lived during the late Eocene period CORONODON HAVENSTEINI AETIOCETUS WELTONI WHEN 28 to 24 million years ago WHERE Ancient eastern North Pacific Ocean LENGTH Up to 11 feet 3 5 meters LOOK FOR Wide triangular flat snout with both baleen and teeth present PREHISTORIC PROFILE Although today we divide whales up based on whether they have teeth or baleen Aetiocetus weltoni may have had both With a jaw structure that may have allowed this ancient cetacean to expand its jaw sideways like modern baleen whales Aetiocetus most likely fed on fish by trapping them in their mouth and then pushing the additional water back out Although scientists aren’t sure if the presence of early baleen made this cetacean a true filter feeder the baleen might have helped hold on to slippery fish WHEN About 30 million years ago WHERE Modern Charleston South Carolina LENGTH 16 feet 5 meters LOOK FOR Large whalelike creature with a wide nose and teeth with fanlike edges PREHISTORIC PROFILE Coronodon havensteini used its teeth for both catching prey and filtering food out of the water making it one of the first filter feeding whales First discovered in 2017 Coronodon provides a link between ancient whales and modern baleen whales and is part of a prehistoric group of cetaceans known as archaeocetes Have you ever run your finger along your back teeth You’ll probably feel bumps on the surface Coronodon had bumps all around its teeth which it used to filter its food out of the water Coronodon likely took in a big mouthful of prey and seawater and then forced the water back out of its mouth catching its prey in the fanlike edges of its teeth 12
WAHAROA SWORD SNOUTED WAHAROA RUWHENUA DOLPHIN WHEN 27 3 to 25 2 million years ago WHERE Modern South Island of New Zealand LENGTH 16 1 2 to 19 1 2 feet 5 to 6 meters LOOK FOR Long thin mouth that opens past the eyes with teeth at the end of each jaw PREHISTORIC PROFILE Hey Waharoa ruwhenua why the long face Scientists think that these early cetaceans probably weren’t lunging predators but rather filtered their food out of the water making them one of the early relatives of modern baleen whales Because their jaws were very long and thin they were also delicate and there is evidence that their jaws did not get incredibly long until adulthood as scientists have found multiple fossils for this species at all different ages Because of their incredibly large jaw they were given the Maõri name waharoa which both means gateway and is the name of the horse mussel a mussel with a long thin wedge shaped shell that looks similar to Waharoa’s jaw EURHINODELPHIS LONGIROSTRIS WHEN About 23 to 5 million years ago WHERE Modern Belgium France and Maryland LENGTH 6 1 2 feet 2 meters LOOK FOR A long thin snout PREHISTORIC PROFILE Think about a swordfish with its long pointed snout The sword snouted dolphin had a very similar and sharp nose that it probably used to hunt prey Fossils of this prehistoric cetacean have been found in Europe and the United States and these sword snouted dolphins lived during the Miocene period They had complex ear bones that scientists believe may have been used for a form of echolocation 13
