In the Mesozoic era a great diversification of reptiles took place. These animals colonized all media: land, air and water. The marine reptiles grew to enormous proportions. For this reason, some people know them as sea dinosaurs.
However, the great dinosaurs never colonized the oceans. In fact, the famous marine dinosaur from Jurassic World is actually another type of giant reptile that lived in the sea during the Mesozoic. Therefore, in this article on our site, we are not going to talk about types of marine dinosaurs, but rather about other giant reptiles that inhabited the oceans.
Differences between dinosaurs and other reptiles
Due to their large size and at least apparent ferocity, giant marine reptiles are often classified as types of marine dinosaurs. However, the large dinosaurs (class Dinosauria) never lived in the ocean. Let's see the main differences between both types of reptiles:
- Taxonomy: Except for turtles, all the great reptiles of the Mesozoic are included within the diapsid sauropsids. This means that they all had two temporal pits in their skulls. However, dinosaurs belong to the group of archosaurs (Archosauria), such as pterosaurs and crocodiles; while the large marine reptiles constituted other taxa that we will see later.
- Pelvic structure: the pelvis of both groups had a different structure. As a result, the dinosaurs had a rigid posture and the body was supported by the legs, located below it. Marine reptiles, however, had their legs extended to both sides of the body.
Types of marine dinosaurs
Dinosaurs, contrary to popular belief, did not become completely extinct The ancestors of birds survived and had a huge evolutionary success, colonizing the entire planet. The current birds belong to the class Dinosauria, that is, are dinosaurs
Since there are birds that live in the seas, we can say that there are some types of marine dinosaurs, such as penguins (family Spheniscidae), loons (family Gaviidae) and gulls (family Laridae). There are even aquatic freshwater dinosaurs, such as the cormorant (Phalacrocorax spp.) and all the ducks (family Anatidae).
If you want to know more about the ancestors of birds, we recommend this other article on Types of flying dinosaurs. But, if you want to know the great marine reptiles of the Mesozoic, read on!
Types of marine reptiles
The large reptiles that inhabited the oceans during the Mesozoic are included in four groups, if we include the chelonioids or sea turtles. However, let's focus on the poorly known types of marine dinosaurs:
- Ichthyosaurs
- Plesiosaurs
- Mosasaurs
Now, let's see one by one who these large marine reptiles were.
Ichthyosaurs
Ichthyosaurs (order Ichthyosauria) were a group of reptiles with an appearance similar to cetaceans and fish, however, they did not they are related. It is an evolutionary convergence, that is, they acquired similar structures as a result of adaptation to the same environment.
These prehistoric marine animals were adapted to hunting in the depths of the ocean. Like dolphins, they had teeth and their favorite prey were squid and fish.
Examples of ichthyosaurs
Here are some examples of ichthyosaurs:
- C ymbospondylus
- Macgowania
- Temnosontosaurus
- U tatsusaurus
- Ophthalmosaurus
- S tenopterygius
Plesiosaurs
The order Plesiosauria includes some of the largest marine reptiles in the world, with specimens up to 15 meters long. For this reason, they are usually included within the types of "marine dinosaurs". However, these animals became extinct in the Jurassic, when the dinosaurs were still in full swing.
Plesiosaurs looked like a tortoise, but longer and without a shell. It is, as in the previous case, an evolutionary convergence. They are also the animals most similar to representations of the Loch Ness monster. Like this one, plesiosaurs were carnivorous animals and are known to have eaten molluscs, such as the extinct ammonites and belemnites.
Examples of plesiosaurs
Some examples of plesiosaurs are:
- Plesiosaurus
- Kronosaurus
- Plesiopleurodon
- Microcleidus
- Hydrorion
- Elasmosaurus
Mosasaurs
Mosasaurs (family Mosasauridae) are a group of lizards (suborder Lacertilia) that were the dominant marine predators during the Cretaceous. In this period, the ichthyosaurs and plesiosaurs had already become extinct.
These aquatic “dinosaurs” between 3 and 18 meters long physically resembled a crocodile. These animals are thought to have lived in warm, shallow seas where they fed on fish, diving birds, and even other marine reptiles.
Examples of mosasaurs
Here are some examples of mosasaurs:
- Mosasaurus
- Tylosaurus
- Clidastes
- Halisaurus
- Platecarpus
- Tethysaurus
The Jurassic World sea dinosaur is Mosasaurus, and since it's 60 feet long, it might be M. hoffmanni, the largest known “marine dinosaur” to date.
