Frozen fossils

A treasure trove of fossils have been found at the top of the world. Since the 2004 discovery, paleontologists contended with polar bears and extreme weather in Spitsbergen, Norway (video here), to excavate the remains of giant sea monsters of the Jurassic Era (about 150 million years ago):

Pliosaurs had massive heads and are often compared to crocodiles, but had bigger muscles and huge, robust jaws that gave it a bite strong enough to bite a small car in half. They had teardrop-shaped bodies with 2 sets of powerful flippers that they used to propel themselves through the water. "We don't think they were particularly good at cruising but were very good at accelerating, so they'd lurk in the depths and shoot up to catch things." Pliosaurs were longer than humpback whales, making them the top marine predators of their time.

Ichthyosaurs looked a bit like modern dolphins, but used an upright tail fin to swim through the water. They had big eyes and 3' snouts equipped with roughly 100 teeth that made up approximately 1/6th of their 20' length.

As can be seen in these artist's renderings by Tor Sponga (more here), ichthyosaurs ate ammonites, fish, and squid. Pliosaurs ate ichthyosaurs.