What is NOT a dinosaur? (In The Sea)

During the Mesozoic era, the seas were teaming with life. As creatures of all shapes and sizes were filling the skies, the sea was home to a myriad of aquatic wonders. Some are relatives of some of todays marine life, like sharks and whales. Others were unique animals who's lineage died along with the many of the dinosaurs. We will be strictly speaking of vertebrates, but be assured, there were many invertebrates inhabiting the seas as well. Some were food for the animals we will be discussing! Since the focus of the site is dinosaurs, I'm not going to get into too much detail about every group of marine reptiles.

The Triassic period gave rise to many different types of marine reptiles. Placodonts are described as having the appearance of a walrus-turtle combo. Very strange, to say the least. There favorite food was mollusks (clams, snails, mussels). They were between 3-6 feet in length, had clawed hands and feet, came in an armored and unarmored variety, and fed primarily at the sea bottom.

Nothosaurs looked a little more like your classic "sea monster". They had a somewhat long neck, four clawed appendages that were most likely webbed to make it easier to propel the animal through water. They grew to about 10 feet in length and their diet consisted mainly of fish. Some people have suggested that they may have had a seal-like lifestyle, waddling themselves onto land occasionally, but spending most of their time in the water.

Nothosaurs and Pacodonts nver made it past the Triassic. But another group, ichthyosaurs, made it all the way through to the mid Cretaceous. Ichthyosaurs sort of resembled dolphins, but with longer snouts (among other differences). They had four "flippers" made up of many tiny bones. They came in many sizes. The largest almost 50 feet long! They had two main body types. Lizard shaped and fish shaped. Fish-shaped version resemble dolphins and the lizard-shaped ones looked like sharks. Many ate fish, but it seems squidlike creatures were a favorite.

Plesiosaurs are some of the most recognized sea creatures of the mesozoic. They are the classic "Loch Ness Monster"-looking creature. They arrived in the late Triassic Period and lasted on through the late Cretaceous. Their typical description is long neck, wide body, short tail, and four flippers. They came in two types: long neck, small head (plesiosaurs), short neck, large head (pliosaurs). An example of a pliosaur would be lipleurodon, which was seen in the television show, Walking with Dinosaurs. Their size ranged from 6 feet to 65 feet. They seemed to eat anything and everything, depending on where they lived and on individual species preferences.

During the Cretaceous, plesiosaurs had competition from some other large marine reptiles called mosasaurs. They are thought to be related to the Komodo dragon or perhaps even snakes. Their bodies were similar in shape to a large lizard as was the head filled with many sharp teeth. Their bodies were very long ending with a long, flat tail. They also had four flippers, the front ones sometimes slightly larger than the rear ones.Their size ranged from 3 feet in length to around 60 feet.

These are by no means all the marine life that was abundant during the Mesozoic Era. These are just some examples of some of the more famous and recognizable creatures that inhabited the seas. Perhaps, in the future I will delve more deeply into Mesozoic sea life, but for now these should give you some idea of what kinds animals inhabited the sea at the same time as the dinosaurs ruled the land.