PALEOWORLD: Sea Monsters

Near Medicine Bow, Wyoming Dr. Robert Bakker hunts for Ichthyosaur fossils. The area was under water as part of the Tethys Sea during the age of reptiles @ 240 million years ago.
In the global Tethys Sea plankton was abundant providing food for numerous fish. They intern would provide food for sea going reptiles as they evolved. Reptiles were driven to the marine environment due to pressures on land.
In 1987 Dr. Chris McGowan of the Royal Ontario Museum searched for the earliest of the marine reptile predators. Ichthyosaurs (Fish Lizards) were dolphin-like in appearance and could swim at @ 45 mph. They ranged from salmon to whale sized and had very large eyes for hunting in dimly light water. They also gave live birth and were both predators and cannibals. The first fossils of the type were discovered in
England in 1811.
In the lime stone quarries (Poseidon Slates) of Holzmaden, Germany over 3,000 skeletons have been excavated. The area was a lagoon @ 160 million years ago.
The Half Museum in Stutgart, Germany has a fossil Plesiosaur dating from the 1790's. The Plesiosaurs were predators in Cratonic Seaways (inland waterways) found toward the centers of most continents during the age of reptiles.
190 million years ago Plesiosaurs dominated the seas. They averaged @ 5 tons, had long necks, and 4 flippers. There were @ two dozen species. The short necked species were called Pliosaurs. They could swim at @ 35 mph. The largest species of this type @ 130 million years ago was the Kronosaur. It was about 50 feet long and had a 12 foot head.
Elasmosaurs were the large long necked species. The largest was Mosasuchus maximus. It was @ 40 feet long. Dr. Bill Galliger of the New Jersey Museum studies this species. He has found that it had double hinged jaws and secondary teeth on The ptergoid bone.
The giant sea reptiles disappeared at the end of the Cretaceous. Dr. Bakker indicates that there have been 6 major dinosaur extinctions. The extinction in question probably occurred because of plankton dieing out at the time and starvation taking its toll.
25 million years ago another giant predator swam the seas. It was the giant shark Megalodon. It is suspected that these feed upon whales and dolphins. Dr. Michael Godfreid of the Calbert Marine Museum studies the fossil of these along the Chesapeake Bay. They were @ 50 feet long and had 6 inch serrated
teeth.
Sharks have cartilage skeletons so fossil remains are poor.
About 50 million years ago a wolf-like predator hunted fish at the edges of the Tethys Sea.
Fossils of early whales are studied at Shark Tooth Hill. Dr. Larry Barnes is a major scientist involved.
In 1859 Charles Darwin published “Origin of the Species.” In this book he speculated about the possibility of a bear-like animal hunting at the edge of the sea as the fore runner of whales. He was laughed at.
In 1861 Archaeopteryx was discovered. It is the missing link between birds and reptiles.
In 1834 Dr. Richard Harlan discovered Basilosaurus in Louisiana. It is a primitive whale.
In 1989 in Egypt Dr. Philip Gainbridge of the University of Michigan found the fossil of a primitive whale with small legs.
In 1983 in Pakistan the fossils of Pakicetus was found. It has a wolf-like skull indicating that it was evolved from a creature called a Mesonichid. These were much like wolfs and lived near the edge of the sea hunting fish.
In 1993 Indocetus was found in India. It is a prehistoric whale with fused tail bones and hind legs.
In 1994 Dr. Hans Tawasen from North Easter Ohio College of Medicine discovered the fossils of Ambulocetus natans. The names means walking swimming whale. It swam with its feet like seals do today.
Dr. Philip Gainbridge found Rhodocetus. It is the earliest known whale to swim by moving it’s tail up and down. Between 1987 and 1994 most of the fossils of whales have been found.
Sea Cows and manatees followed the same style of evolution. Their fossils have also been found on Shark
Tooth Hill in California.