Whats the definition of plesiosaur?

What is the meaning of plesiosaur?

Definition of plesiosaur. : any of an order or suborder (Plesiosauria) of large carnivorous marine reptiles of the Mesozoic with dorsoventrally flattened bodies and limbs modified into flippers.

What is the difference between Plesiosauria and Plesiosauroidea?

“Plesiosauroidea” and “Pliosauroidea” today have a more limited meaning. The term “plesiosaur” is properly used to refer to the Plesiosauria as a whole, but informally it is sometimes meant to indicate only the long-necked forms, the old Plesiosauroidea.

What is the difference between ichthyosaurs and plesiosaurs?

In the early nineteenth century, plesiosaurs were still poorly known and their special build was not understood. No systematic distinction was made with ichthyosaurs, so the fossils of one group were sometimes combined with those of the other to obtain a more complete specimen.

What is the difference between a plesiosaur and Plesiosaurus?

The term “plesiosaur” is properly used to refer to the Plesiosauria as a whole, but informally it is sometimes meant to indicate only the long-necked forms, the old Plesiosauroidea. Skeletal elements of plesiosaurs are among the first fossils of extinct reptiles recognised as such.

Are sea turtles and Plesiosauria the same?

This group includes a number of different species, all of which were marine reptiles. Even the smallest plesiosauria were much bigger than sea turtles today. Plesiosauria ranged from more than 12 feet long to over 60 feet. They were present on Earth for about 155 million years, from the late Triassic through the late Cretaceous.

What are the characteristics of ichthyosaurs?

Ichthyosaurs were shaped like modern dolphins, a streamlined body that made them the fastest of marine reptiles. Like marine mammals, they breathed air, gave birth to live young and were probably warm-blooded. Ichthyosaurs had large eyes for seeing in deep water, vertical tail fins (like tuna fish), and some species had a dorsal fin.

What are pelycosaurs and ichthyosaurs?

Pelycosaurs were primitive ‘synapsids’ – vertebrates whose skulls have one opening to the rear of each eye socket (reptiles have two openings). Mammals are the only surviving synapsids. Ichthyosaurs were shaped like modern dolphins, a streamlined body that made them the fastest of marine reptiles.

What is the difference between ichthyosaur and Dolphin?

While the earliest known members of the ichthyosaur lineage were more eel-like in build, later ichthyosaurs resembled more typical fishes or dolphins, having a porpoise-like head with a short neck and a long snout.

Is Thalattosauria a sea turtle?

Prior to the appearance of the sea turtles, at least two groups of turtles are found from marine environments but they did not survive for very long. Thalattosauria has been an enigmatic group of marine reptiles that is not counted in the four major groups designated earlier in this paper.

What are the marine reptiles of the Mesozoic era?

Marine reptiles were especially successful in the Mesozoic as major predators in the sea. There were more than a dozen groups of marine reptiles in the Mesozoic, of which four had more than 30 genera, namely sauropterygians (including plesiosaurs), ichthyopterygians, mosasaurs, and sea turtles.

What happened to marine reptiles in the Early Jurassic period?

For example, the Early Jurassic saw the invasion of the sea by thalattosuchians and pleurosaurs, and this was some time after most of the coastal marine reptiles of the Triassic became extinct. The two groups became extinct in the Early Cretaceous, some time before mosasaurs and sea turtles appeared.

Were pelycosaurs the first mammals?

Although pelycosaurs were the earliest “mammal-like reptiles”, there are only a few characteristics which have been modified from the ancestral condition of the anapsid reptiles.   The most prominent are the synapsid opening and the presence of canines.

What is the difference between a lepidosaur and pelycosaur?

Unlike lepidosaurian reptiles, pelycosaurs lacked reptilian epidermal scales. Fossil evidence from some varanopids shows that parts of the skin were covered in rows of osteoderms, presumably overlain by horny scutes. The belly was covered in rectangular scutes, looking like those present in crocodiles.

Are pelycosaurs reptiles?

This means that the pelycosaurs are not reptiles, since reptiles have two such openings in their skulls. Like most other groups of synapsids, all pelycosaurs are now extinct. In fact, the only currently living synapsids are the mammals.

What are the two groups of pelycosaurs?

PELYCOSAURS. Synapsid Reptiles and Mammals Synapsid reptiles and the mammals that evolved from them form one monophyletic clade. There are two groups of synapsid reptiles, the pelycosaurs and the therapsids, the latter of which includes an advanced group known as the cynodonts.

What animal is most similar to a dolphin?

Ichthyosaurs (Greek for “fish lizards”) were similar to dolphins in another, perhaps even more telling way.

How are dolphins and ichthyosaurs similar?

Ichthyosaurus that lived 180 million years ago were like dolphins because they were WARM BLOODED, covered in blubber and had camouflaged skin. Ichthyosaurs, ancient marine reptiles from the Jurassic era that resembled dolphins, were like their modern counterparts in more ways than one, research suggests.

What was the first thalattosaur reptile?

The first record of a thalattosaur reptile from the Late Triassic of southern China (Guizhou Province, PR China). J Vertebr Paleontol. 2000;20:507–14. doi: 10.1671/0272-4634 (2000)020 [0507:TFROAT]2.0.CO;2. Rosenzweig PA. Estuarine crocodiles. In: Carpenter KE, Niem VH, editors. FAO species identification guide for fishery purposes.

Were there dinosaurs in the Mesozoic ocean?

The Mesozoic oceans played host to a myriad of large reptiles, including ichthyosaurs, plesiosaurs, nothosaurs, placodonts, and mosasaurs. Each of these groups of reptiles contained many species, some among the largest creatures ever to live in the oceans, and none of them were dinosaurs.

When did marine reptiles become extinct?

The two groups became extinct in the Early Cretaceous, some time before mosasaurs and sea turtles appeared. The highest diversity of marine reptiles was achieved in the Triassic. Different groups of Mesozoic marine reptile adopted different swimming styles.

What animals lived in the sea during the Jurassic period?

During the Jurassic period, the primary vertebrates living in the sea were fish and marine reptiles. The latter include ichthyosaurs, who were at the peak of their diversity, plesiosaurs, pliosaurs, and marine crocodiles of the families Teleosauridae and Metriorhynchidae.

What did the first pelycosaur eat?

The first known pelycosaurs were large reptiles with large skulls and large canine teeth.   These pelycosaurs were adapted to eating large prey and were the first carnivorous amniotes (Kemp, 1982; Carroll, 1988).

What are the characteristics of Lepidosauria?

A well-developed median or pineal eye is present on the top of the head (parietal region) and an additional row of upper teeth is located on the palatine bone. The reptiles in the subclass Lepidosauria can be distinguished from other reptiles by a variety of characteristics.