History UsefulNotes / StockDinosaursNonDinosaurs

Despite this, Pliosaurs have been the least-portrayed group of sea-reptiles, and still remain mainly documentary-animals. The kronosaur has long been the most commonly shown pliosaur in books and documentaries until 1999, when a memorable appearance of an [[RuleOfCool extraordinarily oversized]] [[note]]The fictional length 80ft/25m was based on misidentified bone fragments; in reality, the species maxed out at 25ft/7m long.[[/note]] ''Liopleurodon'' on WalkingWithDinosaurs rapidly made it the new iconic member of the family (very similarly to ''Deinonychus'' à ''Velociraptor'' thanks to ''Film/JurassicPark''). In the show, an old male liopleurodon was described weighing 150 tons (a bit less than the Blue Whale) and [[UpToEleven the biggest predator of all time]]. In particular, the scene in which he pulls the ichthyosaur in pieces [[NightmareFuel disturbed many viewers]] (even though the sad final scene where he’s stranded and slowly dies gives it a bit of humanity). To give the idea about how the animal remained impressed in pop-consciousness: [[FollowTheLeader all successive depictions]] have shown Liopleurodons with the WWD blue-white color-patterns. [[note]]For some reason, unlike dinosaurs and pterosaurs, marine reptiles are almost-always shown with dull colors even in modern portraits. However, they could have been very colorful like modern tropical seagoing animals.[[/note]] Meanwhile, CharlieTheUnicorn managed to bring ''Kronosaurus'' to the status of minor Internet meme. Another species that is starting to rise in popularity is the recently discovered ''Pliosaurus'' ''funkei'', known in popular culture as ''Predator'' ''X''. At an estimated 10-13 metres, it's likely that it was the largest of this group and this was coupled with a bite that was estimated to be four times that of T-rex. Is it any wonder this thing is becoming popular?

Despite this, Pliosaurs have been the least-portrayed group of sea-reptiles, and still remain mainly documentary-animals. The kronosaur has long been the most commonly shown pliosaur in books and documentaries until 1999, when a memorable appearance of an [[RuleOfCool extraordinarily oversized]] [[note]]The fictional length 80ft/25m was based on misidentified bone fragments; in reality, the species maxed out at 25ft/7m long.[[/note]] ''Liopleurodon'' on WalkingWithDinosaurs rapidly made it the new iconic member of the family (very similarly to ''Deinonychus'' à ''Velociraptor'' thanks to ''Film/JurassicPark''). In the show, an old male liopleurodon was described weighing 150 tons (a bit less than the Blue Whale) and [[UpToEleven the biggest predator of all time]]. In particular, the scene in which he pulls the ichthyosaur in pieces [[NightmareFuel disturbed many viewers]] (even though the sad final scene where he’s stranded and slowly dies gives it a bit of humanity). To give the idea about how the animal remained impressed in pop-consciousness: [[FollowTheLeader all successive depictions]] have shown Liopleurodons with the WWD blue-white color-patterns. [[note]]For some reason, unlike dinosaurs and pterosaurs, marine reptiles are almost-always shown with dull colors even in modern portraits. However, they could have been very colorful like modern tropical seagoing animals.[[/note]] Meanwhile, CharlieTheUnicorn managed to bring ''Kronosaurus'' to the status of minor Internet meme.

It's worth noting that mammoths, scientifically speaking, are just another type of elephant, since they belong to the same phylogenetic branch. An Asian Elephant is slightly more closely related to ''mammoths'' than to his more distant African modern relative (thus mammoths ''weren't'' the direct ancestors of elephants as heard sometimes). On the other hand, the Mastodon is ''not'' a true elephant but just a distant relative of ''both'' modern pachyderms ''and'' mammoths -- its scientific name, ''Mammut americanum'', is misleading). For other extinct elephant relatives, see [[UsefulNotes/PrehistoricLifeMammals Prehistoric Life]].

Its striking look, the earliness of its discover and the completeness of many remains have contributed to make ''Rhamphorhynchus'' the second most commonly portrayed pterosaur in media—expecially the older ones. ''Rhamphorhynchus'' has become quite rare today--pterosaurs shown in the most recent movies generally are ''Pteranodon'', ''Quetzalcoatlus'', or (more often) imaginary Giant Fliers.

Not all Mesozoic reptiles were exotic critters, however. ''Archelon'' was just what it seems: just a sea-turtle. But it fits perfectly the subtrope "Everything was huge at dinosaur times": it's the largest known fossil turtle--4 m/13 ft long and weighing some tons, ''Archelon'' was 2-3 times bigger than the biggest modern turtle (the [[http://en.wikipedia.org/wiki/Dermochelys_coriacea Leatherback turtle]], confirming TurtlePower is TruthInTelevision. However, it was not the ancestor of modern sea-turtles: it pertained to a different lineage, the Protostegids, which went extinct along the other giant reptiles at the end of the Cretaceous. Its name is a {{Portmanteau}} of ''arche'' (primeval) and ''chelon'' (turtle).

Descended from a still-unknown land-living ancestor (remember ''every'' lineage of marine reptiles did descend from four-limbed terrestrial reptiles), Ichthyosaurs were the most marine of all marine reptiles and never came onto land, not even for laying their eggs. In fact, their young were born alive just like modern dolphins, as we can see in some fossils of mothers dead with their offspring ''just getting out of their body''. We now know that plesiosaurs also reproduced in the same way and probably never left the water either -- however, the scene of a long-necked plesiosaur which crawls on the seashore like a sea-lion is a [[RealityIsUnrealistic staple in artworks]]. Ichthyosaurs are extremely abundant in fossil record: several individuals are preserved with soft tissue and, sometimes, ''even the print of the whole body''. Thanks to the latter, we know they had a dorsal fin and a crescent-shaped caudal fin other than the four paired "flippers." A strange thing is, unlike modern sharks, the backbone curved ''downwards'' at the tail level, and filled the lower lobe of the caudal fin, not the upper one.

# '''TropeMaker:''' ''Film/OneMillionYearsB.C.''

More archaic than ''Rhamphorhynchus'', ''Dimorphodon'' shows several primitive traits which betray how dinosaurs and pterosaurs were closely related. The three free wing-fingers were strong and large-clawed, not unlike those of a feathered theropod. The hindlegs were long and powerful, and the animal could have walked bipedally used its long tail for balance. Its stocky skull was more similar to a theropod dinosaur than to a pterosaur, with nasal openings on the tip of the nose (most pterosaurs had nostrils just in front of the eyes).

# '''Entry Time:''' 1864 (''Plesiosaurus''); 1933 (''Elasmosaurus'')
# '''TropeMaker:''' ''JourneyToTheCentreOfTheEarth'' (''Plesiosaurus''); ''Film/KingKong'' (''Elasmosaurus'')

# '''TropeMaker:''' WalkingWithDinosaurs''JourneyToTheCentreOfTheEarth''

# '''Entry Time:''' 1864
# '''TropeMaker:''' ''JourneyToTheCentreOfTheEarth''

# '''TropeMaker:''' ''Film/OneMillionYearsBC

# '''Entry Time:''' 1852
# '''TropeMaker:''' Crystal Palace Park

Possibly thanks to their dinosaurian-look and the association with snakes, Plesiosaurs have been the most iconic and depicted sea reptiles in media. Like dinosaurs and pterosaurs, expect to see them as [[PrehistoricMonster scary monsters]] with an [[EverythingTryingToKillYou killing attitude towards humans]]. If alive today, even the biggest Elasmosauruses wouldn’t be more aggressive than most whales (although they could unintentionally capsize your tiny boat or raft). And every time a plesiosaur shows up, ''someone'' will bring up the [[StockNessMonster Loch Ness Monster]].

The long-necked plesiosauroids belong to the Sauropterygian supergroup, which also includes the Pliosaurs (or Pliosauroids) and other less-known groups of sea-reptiles. Together, Plesiosauroids and Pliosauroids make the Plesiosauria, a.k.a. "plesiosaurs" in broader sense, originated from the same common ancestor in the Triassic seas. Their relationship of Sauropterygians with modern reptiles has long been unclear. Once, they were placed with Ichthyosaurs in their own subgroup (see further), and not related with any still-living reptilian group. Today, plesiosaurs sensu lato (pliosaurs included) are thought not closely related to ichthyosaurs. They seem only loosely related with modern lizards, rather that with crocodiles and dinosaurs.

Despite this, Pliosaurs have been the least-portrayed group of sea-reptiles, and still remain mainly documentary-animals. The kronosaur has long been the most commonly shown pliosaur in books and documentaries until 1999, when a memorable appearance of an [[RuleOfCool extraordinarily oversized]] [[note]]The fictional length 80ft/25m was based on misidentified bone fragments; in reality, the species maxed out at 25ft/7m long.[[/note]] ''Liopleurodon'' on WalkingWithDinosaurs rapidly made it the new iconic member of the family (very similarly to ''Deinonychus'' à ''Velociraptor'' thanks to ''Film/JurassicPark''). In the show, an old male liopleurodon was described weighing 150 tons (a bit less than the Blue Whale) and [[UpToEleven the biggest predator of all time]]. In particular, the scene in which he pulls the ichthyosaur in pieces [[NightmareFuel disturbed many viewers]] (even though the sad final scene where he’s stranded and slowly dies gives it a bit of humanity). To give the idea about how the animal remained impressed in pop-consciousness: [[FollowTheLeader all successive depictions]] have shown Liopleurodons with the WWD blue-white color-patterns. [[note]]For some reason, unlike dinosaurs and pterosaurs, marine reptiles are almost-always shown with dull colors even in modern portraits. However, they could have been very colorful like modern tropical seagoing animals.[[/note]] While WWD may have made ''Liopleurodon'' the Stock Pliosaur in place of ''Kronosaurus,'' CharlieTheUnicorn managed to bring it to the status of minor Internet meme.

Its worth noting, however, that ScienceMarchesOn has been a crucial factor in pterosaur portraits. Like dinosaurs, pterosaurs have undergone a sort of scientific "renaissance" since the seventies: traditionally described as awkward, cold-blooded gliders, then it has become clear that they were instead active and efficient fliers, ''covered with down'' like several dinosaurs and with high-rate metabolism. Nevertheless, even today they remain one of the most enigmatic group of prehistoric beasts, as their fossil record has always been one of the scarcest of all. Sadly, these issues are usually glossed over in pop-media, even today. See PteroSoarer to get into this in depth.

* Expecially in older media, they are often portayed with [[MixAndmatchCritter Bat Wings]], tying into the whole DinosaursAreDragons thing. Actually their wing-membranes were substained by ''only one'' overly-long digit, the fourth one (not the fifth as sometimes heard), which was as robust as the rest of the forelimb. The 1°, 2°, and 3° finger were normal-sized and protruded from the anterior wing-edge like the 1° digit of modern bats. More persistant is the depiction of the wings as loose, bat-like flaps of skin -- in RealLife, the wing membranes were thin but taut sheets of muscle, containing several distinct layers of complex muscle fibers which essentially made them into shape-shifting organs for on the fly adjustments.

Pliosaurs were variably-sized, some were not bigger than dolphins, but the biggest one are candidates for "the largest sea reptile" title –- even though their size has often been exagerrated. Among the latter, ''[[http://en.wikipedia.org/wiki/Liopleurodon Liopleurodon]]'' and ''[[http://en.wikipedia.org/wiki/Kronosaurus Kronosaurus]]'', were among the top-predators of the Jurassic and early Cretaceous oceans respectively. Once extimated 16 m long (10 m are more likely), ''Kronosaurus'' is named from Cronus, a Greek goddity who [[IAmAHumanitarian devoured its own offsprings]] (Zeus and Poseidon among them). About the same length was the less-coolly named ''Liopleurodon'', virtually identical to the former but with less teeth. As is usual with marine superpredators, both are usually depicted as [[CarnivoreConfusion merciless ever-hungry]] [[PrehistoricMonster killing machines]].

[[http://en.wikipedia.org/wiki/Pterosauria Pterosaurs]] (usually called ''Pterodactyls'' in media and in pop-language) are often referred as the "flying dinosaurs"; they actually were closely related with them, but technically were not true dinosaurs.

Similarly, these animals are often collectively referred to as "swimming dinosaurs," but this time they were ''not'' close relatives of true dinosaurs; some of them were not even related each other. If you'd like to see a seagoing dinosaur, watch ''[[EverythingsBetterWithPenguins March of the Penguins]]''.

''Pteranodon''’s nifty crest on its skull, along with the fact to have holded the size-record for almost a century, has made it THE pterosaur in popular imagination. Its iconic status among pterosaurs coud be partially justified. It’s not only one of the first discovered pterosaurs, but perhaps also the most common in fossil record. Hundreds of specimens are known, while most other pterosaur kinds are much, much rarer, often known from a single individual. The vast majority of Pteranodons belong to the species all people know, ''Pteranodon longiceps''.

!!Examples:

[[AC:Advertising]]
* Appears in the third Volvic bottled water ad.

* They weren't either dinosaurs, nor were they birds. Further, they were not even the ancestors of any modern flier[[labelnote:*]]dinosaurs were[[/labelnote]]: instead, they were only ''relatives'' of dinosaurs (and thus birds, of course).

Surprisingly, stock pterosaurs are ''not'' (necessarily) the biggest/coolest-looking ones --three out of five are not bigger than an eagle or a stork. Instead, they were among the very first scientifically-described kinds, in the XIX century. ''Pterodactylus'', ''Rhamphorhynchus'', and ''Dimorphodon'', [[labelnote:*]]The normally-sized ones[[/labelnote]] were discovered in Europe ''before'' the 1820s (the decade in which the "first dinosaurs" were named). The last two were initially classified as ''Pterodactylus'' and recognized distinct only after the 1820s. With its 7 m/24 ft wide wingspan, ''Pteranodon'' was found in USA in the last quarter of the XIX century, during the "Bone Wars." [[labelnote:**]]Oddly, it too was initially classified as ''Pterodactylus''.[[/labelnote]] Its sheer size ("Whoa the biggest flier ever!") and its crest soon made it the new iconic pterosaur, and still preserves its status today.

Several interesting new pterosaurs were discovered in the second half of the XX century, but only one managed to achieve some consideration in media: ''Quetzalcoatlus'', because was the only one clearly bigger than the pteranodont, and the new "biggest flying animal ever." In the 2000s, ''Ornithocheirus'' gained some popularity as well thanks to a memorable apparition in ''WalkingWithDinosaurs'', but only because was (wrongly) described as [[UpToEleven the biggest flying animal ever existed]]. The others (''Dsungaripterus'', ''Pterodaustro'', ''Tapejara'', ''Eudimorphodon'', ''Sordes'', and so on) were largely ignored outside dino-books and documentaries. If you’re searching for these and other non-stock pteros, go [[UsefulNotes/PrehistoricLifeNonDinosaurianReptiles here]].

The backwards-pointing crest is the most striking feature of ''Pteranodon''. It was laterally flattened in RealLife, but in media expect to see it with a conical shape, often resembling a ''horn''. The real purpose of this crest is still unclear. It is traditionally described as a sort of balancing-pole to better balance the long head, or as a rudder to maintain it stabilized during flight. However, this doesn’t explain why only males had such a big crest, while the females’ one was extremely shortened. Once was thought long- and short-crested individuals belonged to different species. [[labelnote:*]]An astounding thing is, short-crested pteranodonts are ''almost never'' shown even in documentary media![[/labelnote]] This bony protrusion could simply be a display device, like is hypothized as well for Stegosaur’s plates, Triceratops’ horns and frill, Spinosaurus "sail," and so on. This could explain why the males’ one was so big compared with the females.

In RealLife, ''Pteranodon'' was substantially a giant pelican in behaviour. Its long toothless beak was useful to catch fish, and the shape of its lower jaws seem to show a sort of "pouch" to store fish in flight, even though this is not sure. If alive today, ''Pteranodon'' could not be that danger for us folks as shown everywhere in media. Weighing only about 20 kg, [[labelnote:**]]Compared to body size pterosaurs were even lighter than birds, having totally hollow bones like straws. For example, the prehistoric vulture ''Argentavis'' had a similar wingspan of the pteranodont, but is extimated 80 kg.[[/labelnote]] was too light to lift a 70 kg man up in the air. And if it really could have done so, certainly didn’t with its weak hindlimbs but with the mouth instead. Finally, since its beak was straight and smooth-edged, a child could easily have got out of it by wriggling.

!!Examples

[[AC:Advertising]]
* Features in the second Volvic bottled water ad.

Like ''Pteranodon'', ''Rhamphorhynchus'' tends to be portrayed incorrectly in fiction, often as big as a pteranodont or even bigger. Another classic mistake is to show rhamphorhynchs with flexible tails (a bit like what happens to "raptors") and sometimes with ''triangular'' fins. Actually their tail was stiffened by bony tendons, and was a steering device during flight. [[labelnote:*]]It's not to exclude that only males had the "fin." If so, this thing could have been for display.[[/labelnote]] Finally, a very Undead-Horse subtrope is to apply the "devilish" rhamphorhynchoid tail to [[RuleOfCool every]] [[TheyJustDidntCare other]] [[MixAndMatchCritter pterosaur]], expecially ''Pteranodon''. Actually pterodactyloid pterosaurs had stubby tails without distinction.

Despite this, Pliosaurs have been the least-portrayed group of sea-reptiles, and still remain mainly documentary-animals. The kronosaur has long been the most commonly shown pliosaur in books and documentaries until 1999, when a memorable appearance of an [[RuleOfCool extraordinarily oversized]] [[labelnote:*]]The fictional length 80ft/25m was based on misidentified bone fragments; in reality, the species maxed out at 25ft/7m long.[[/labelnote]] ''Liopleurodon'' on WalkingWithDinosaurs rapidly made it the new iconic member of the family (very similarly to ''Deinonychus'' à ''Velociraptor'' thanks to ''Film/JurassicPark''). In the show, an old male liopleurodon was described weighing 150 tons (a bit less than the Blue Whale) and [[UpToEleven the biggest predator of all time]]. In particular, the scene in which he pulls the ichthyosaur in pieces [[NightmareFuel disturbed many viewers]] (even though the sad final scene where he’s stranded and slowly dies gives it a bit of humanity). To give the idea about how the animal remained impressed in pop-consciousness: [[FollowTheLeader all successive depictions]] have shown Liopleurodons with the WWD blue-white color-patterns. [[labelnote:*]]For some reason, unlike dinosaurs and pterosaurs, marine reptiles are almost-always shown with dull colors even in modern portraits. However, they could have been very colorful like modern tropical seagoing animals.[[/labelnote]] While WWD may have made ''Liopleurodon'' the Stock Pliosaur in place of ''Kronosaurus,'' CharlieTheUnicorn managed to bring it to the status of minor Internet meme.

The most recent group of Mesozoic sea-reptiles, Mosasaurs lived worldwide in the Late Cretaceous, at the end of the Age of Dinosaurs. They replaced Ichthyosaurs and coexisting with the last Plesiosaurs. While Ichthyos and Plesios were not closely related with any modern reptile, Mosasaurs are the only prehistoric animals which literally deserve the title of "giant lizards." They belong to the [[http://en.wikipedia.org/wiki/Squamata Squamates]], the group containing modern lizards and snakes [[labelnote:*]]Never forget snakes ''are'' legless lizards just as birds are flying dinosaurs[[/labelnote]], and were closely related to modern snakes and monitor-lizards. Indeed, due to their elongated shape, they have often been compared with the legendary "sea-serpent," and often depicted with a speculative dragon-like crest running along their back in much old paleo-art.

Mosasaurs’ head was similar to modern lizards but with a longer snout. Like the latter, they’d have had fleshy lips. Like modern snakes, their mouth had a notably loose hinge between the jaws: this allowed mosasaurs to swallow big items without tearing them in pieces. The teeth were conical, the upper ones placed in two rows on each half-jaw, again like modern snakes and monitors. According to stomach contents, Mosasaurs were very generalist feeders: fish, sharks, squids, pterosaurs, early birds like ''[[UsefulNotes/PrehistoricLife Hesperornis]]'' and even smaller mosasaurs have been found. [[labelnote:*]]This ''doesn’t necessarily mean'' they were cannibals, though: the preyed mosasaurs could be from different species than their predators. After all, modern orcas do eat smaller dolphins.[[/labelnote]] We don’t known if mosasaurs had a forked tongue and ever-open eyes like many modern squamates, nor if they had heat-sensors like some boas and rattlesnakes: these things usually don't preserve in fossil record.

As turtles and tortoises have virtually remained unchanged since their first apparition in the Triassic, ''Archelon'' had the same traits seen in modern chelonians: beaked jaws, forelimbs transformed in strong flippers (with multiple phalanxes as usual), weaker hind-flippers and short tail. However, its armor was lighter than most modern turtles, and maybe the shell was leathery instead of horny. The modern turtle which mostly resembles an archelon could just be the Leatherback. As modern species of sea turtles eat very different items (some eat shellfishes, others seaweed, and some jellyfishes), we don’t know what were the archelon’s preferences. Certainly it came ashore to lay its eggs like its relatives.

''[[TaxonomicTermConfusion Technically]]'' they are not even "reptiles."

Being a very early mammal-ancestor, ''Dimetrodon'' has still a lizardy shape, with long tail, long body, splayed legs, and skull with a small braincase. Fossil prints show a lizard-like gait. Other traits, on the other hand, were quite mammalian: a laterally-flattened trunk (not wider-than-taller like most modern reptiles); a solid skull with one single pair of temporal opening placed near the maxillary hinge (the so-called "synapsid" condition also seen in mammals, us humans included); and differently-shaped teeth -- ''Dimetrodon'' just means "teeth with two lengths." Even though all teeth were conical, the anterior ones were small and crammed together like incisors, while the longest teeth were in the place mammals have usually their canines. Behind them, the posterior teeth were small and not apt for chewing food unlike our molars, but are somewhat analogue to those seen in primitive insectivorous mammals. More evolved synapsids like ''Cynognathus'' achieved a clearly mammalian anatomy, with more erect limbs, shorter tails, larger brains, and teeth very similar to mammals (see UsefulNotes/PrehistoricLife).

''Dimetrodon'' is usually described as the top-predator of its time, shown hunting early "amphibians" like ''Eryops'', ''Diplocaulus'', ''Seymouria'' etc., as well as what could be called its [[NonIdenticalTwins Non-Identical Twin]], ''Edaphosaurus''. Its crest, its (apparently) [[ReptilesAreAbhorrent reptilian look]] and the meat-eating attitude makes the dimetrodon a predestined victim of DinosaursAreDragons and PrehistoricMonster both in Fiction and in docu-media. However, if compared with other famous prehistoric animals, ''Dimetrodon'' could appear rather [[{{Narm}} narmy]] in comparison. If we imagine a battle against a Tyrannosaurus/Deinosuchus/Smilodon/Mosasaur, the primitive and relatively small dimetrodont would always result the loser -- this could also be true when put against modern predators (lions, kodiak-bears, Nile crocs etc), as well as most ancient and modern giant herbivores. But in Permian landscapes, ''Dimetrodon'' was still faster and more powerful than every other land animal, definitively debunking the {{Narm}} thing.

Although "saber-tooths" belongs to the cat family Felidae, they are in a separate branch of that clade from to modern felines; thus, the popular denomination "Sabertooth tiger" is not correct at all. The "tiger" thing means that ''Smilodon'' is often heard roaring just like an actual tiger or a lion, though only the big cats of the genus ''[[PantheraAwesome Panthera]]'' (that is, Lion, Tiger, Jaguar and Leopard) could make roars thanks to the structure of their larynxes unique of this group. This depiction is, however, vindicated by science, as the structure of the small bones in its mouth are set up for making a sort of roar.

* Expecially in older media, they are often portayed with [[MixAndmatchCritter Bat Wings]], tying into the whole DinosaursAreDragons thing. Actually their wing-membranes were substained by ''only one'' overly-long digit, the fourth one (not the fifth as sometimes heard), which was as robust as the rest of the forelimb. The 1°, 2°, and 3° finger were normal-sized and protruded from the anterior wing-edge like the 1° digit of modern bats. More persistant is the depiction of the wings as loose, bat-like flaps of skin--in RealLife, the wing membranes were thin but taut sheets of muscle, containing several distinct layers of complex muscle fibers which essentially made them into shape-shifting organs for on the fly adjustments.

Very few pterosaurs have been portrayed in non-docu media, despite their notable variety in RealLife. Among pterosaurs listed here, only three can be called “pterodactyls” without getting totally wrong: ''Pteranodon'', ''Quetzalcoatlus'', and of course ''[[ExactlyWhatItSaysOnTheTin Pterodactylus]]''. The other two, ''Rhamphorhynchus'' and ''Dimorphodon'', were more primitive than the former and are usually called “rhamphorhynchs”.

Several interesting new pterosaurs were discovered in the second half of the XX century, but only one managed to achieve some consideration in media: ''Quetzalcoatlus'', because was the only one clearly bigger than the pteranodont, and the new “biggest flying animal ever”. In the 2000s, ''Ornithocheirus'' gained some popularity as well thanks to a memorable apparition in ''WalkingWithDinosaurs'', but only because was (wrongly) described as [[UpToEleven the biggest flying animal ever existed]]. The others (''Dsungaripterus'', ''Pterodaustro'', ''Tapejara'', ''Eudimorphodon'', ''Sordes'', and so on) were largely ignored outside dino-books and documentaries. If you’re searching for these and other non-stock pteros, go [[UsefulNotes/PrehistoricLifeNonDinosaurianReptiles here]].

In popular portrayal, an ever-present mistake is to show Pteranodonts as [[ToothyBird toothy creatures]]. When present, these teeth usually resemble those of the other well-known ptero, ''Rhamphorhynchus'' (see below). The fact that the genus’ name ends in “odon” (meaning tooth in Greek) could lead people in error, too. Actually, “odon” is preceded by the greek “privative A” (becoming “an” when followed by a vowel). Thus, “anodon” means ''with no teeth''. (See also ''[[UsefulNotes/PrehistoricLife Ludodactylus]]''.)

In RealLife, ''Pteranodon'' was substantially a giant pelican in behaviour. Its long toothless beak was useful to catch fish, and the shape of its lower jaws seem to show a sort of “pouch” to store fish in flight, even though this is not sure. If alive today, ''Pteranodon'' could not be that danger for us folks as shown everywhere in media. Weighing only about 20 kg, [[labelnote:**]]Compared to body size pterosaurs were even lighter than birds, having totally hollow bones like straws. For example, the prehistoric vulture ''Argentavis'' had a similar wingspan of the pteranodont, but is extimated 80 kg.[[/labelnote]] was too light to lift a 70 kg man up in the air. And if it really could have done so, certainly didn’t with its weak hindlimbs but with the mouth instead. Finally, since its beak was straight and smooth-edged, a child could easily have got out of it by wriggling.

''Rhamphorhynchus'' (“sharp beak”) was first found in Germany in the XIX century, and lived in the Late Jurassic in the same locations of several other pterosaurs and also ''Archaeopteryx'' and ''Compsognathus''. It was the second named pterosaur after the prototypical ''Pterodactylus'', and the first one known with a long tail. It’s the namesake of the primitive pterosaurs called Rhamphorhynchoids. Like ''Archaeopteryx'', ''Rhamphorhynchus'' has left exquisite remains. Some specimens with prints of wing membranes are known since the XIX century. It was just these ''Rhamphorhynchus''es that definitively showed pterosaurs were airborn critters, not water-living as believed by some at the time.

''Rhamphorhynchus'' had a wingspan of about 2 m / 6 ft, relatively short wings, a narrow snout slightly pointing upwards, robust hindlimbs, and long tail. Two recognizable traits are the protruding teeth and the diamond-shaped “fin” put vertically on its tail-tip. As ''Rhamphorhynchus'' lived in coastal lagoons, the teeth were probably apt to catch fish in flight. The typical tail-fin was made of soft tissue (it’s know only thanks to prints in the rocks).

''Rhamphorhynchus''’ tail has often been compared with a dragon’s or a devil’s, and the large teeth give it a deceptively “menacing” look (actually it wouldn’t be more dangerous than a gull if alive today). We now know it was covered in hair-like structures like its close relative ''[[UsefulNotes/PrehistoricLife Sordes pilosus]]'' (which just means “[[RuleOfCool hairy devil]]”)

This is, for now, the Ultimate GiantFlyer among prehistoric animals. Lived in North-America at the very end of the Cretaceous 70-65 mya (but some think its distribution was worldwide). ''Quetzalcoatlus'' was discovered in the 1970s in Texas from incomplete remains. Its wingspan was extimated from 10 m / 35 ft up to 16 m / 50 ft, with the lower range being the most likely. [[RuleOfCool Of course]], pop-media have often followed the higher one. This “living airplane” took the Pteranodon’s reputation over as “the biggest flier ever” in those years. Its describer named it from an Atzec divinity: Quetzalcoatl, the “feathered snake” (the animal itself is often called “the quetzalcoatl”.)

Several ''Pterodactylus'' species were recognized in the past. Today only one has remained valid, ''Pterodactylus antiquus'', about the same size of a ''Rhamphorhynchus''. Some alleged ''Pterodactylus'' species were described from individuals no bigger than a sparrow: this led the genus to be described as “one of the tinies pterosaurs ever”. [[ScienceMarchesOn Recent research]] suggests these specimens were actually juveniles, which deceptively resemble miniaturized adults. The fact that newborn pterosaurs were virtually identical to adults is a recent discovery which strongly astonished scientists and paleo-fans: none of the still-living fliers shows powered flight soon after its birth.

''Pterodactylus'' was one of the first appeared pterodactyloid pterosaurs (Late Jurassic Europe), and shared its habitat with the more archaic ''Rhamphorhynchus''. Its body-shape was more similar to a miniaturized pteranodont than to a rhamphorhynch, with long, thin jaws, elongated wings, weak hindlimbs, small “wing-hands”, and stubby tail. Usually depicted as a generic-as-it-gets pterosaur, the latest findings show it had a small crest made of skin on the back of its head. Moreover, its apparently generic teeth could have been specialized for something---traditionally described as a fish- or insect-hunter, ''Pterodactylus'' could have been a filter-feeder in coastal lagoons (though not so specialized as another relative, ''[[UsefulNotes/PrehistoricLife Pterodaustro]]'').

''Dimorphodon'' was a rhamphorhynchoid that lived in Early Jurassic, 190 mya. Found in England, it shared with ''Rhamphorhynchus'' the elongated stiffened tail, but we don’t know if it had a “fin”. Its more striking trait is its oversized skull, even bigger than the body itself! Despite appearences, the head of ''Dimorphodon'' was lightened by wide openings in the skull, and the animal couldn’t have troubles to lift it, a bit like modern toucans and hornbills with their beaks.

Its name, “two-shaped teeth”, recalls that of the famous ''Dimetrodon'' (“two-measured teeth”). It had [[ExactlyWhatItSaysOnTheTin two kinds of teeth]] (while most pterosaurs have only one). Some teeth were bigger and sparse among the smaller ones. With this kind of dentition, the feeding habits of ''Dimorphodon'' have always been matter of speculation. It could have been a fisher, a hunter of small land animals, an insectivore, or all these things.

Interestingly, unlike dinosaurs, marine reptiles were ''already'' well-known to science at the beginning of the 19th century. Their fossil record is overall wealthier and better-preserved than that of the dinosaurs. Significantly, the very ''first'' "antediluvian”" reptiles entered in narrative media were not dinosaurs, but the Ichthyosaur and the Plesiosaur which battle each other in the novel ''JourneyToTheCenterOfTheEarth'' written by Jules Verne in 1864. Both animals were enormously oversized and depicted in a ''very'' fanciful way: if you read the novel, you'll find them more like MixAndMatchCritter-related [[SeaMonster sea-monsters]] than their RealLife counterparts. The "ichthyosaur" is similar to a mixup of whales-crocodiles-dragons-snakes-whatnot, and has not the familiar fish-like shape of a RealLife Ichthyosaurus. The plesiosaur is a bit more realistic, but has a serpentine neck and the shell of a sea turtle. However, some of these errors are due to ScienceMarchesOn, as we’ll se in the single sections below.

The association with snakes and turtles seems a constant when talking about plesiosaurs. Even scientists once used to describe these animals as “[[MixAndMatchCritter turtles into a snake’s body]]” or “[[MixAndMatchCritter snakes into a turtle’s body]]”. Their body was actually turtle-like (except for the lack of shell of course), and their neck had a huge number of vertebrae (even 76 in ''Elasmosaurus''!). Classic depictions show plesiosaurs with extremely flexible necks capable to coil and to dart like a snake. ScienceMarchesOn however, and it was discovered in the 2000s (thanks to simulations in CGI) their neck was much more rigid than previously thought, a bit like what is happened to sauropod dinosaurs.

These animals are traditionally described as slow turtle-like swimmers, using their four flippers as oars and propelling awkwardly their bulk through the water. In classic paleo-art plesiosaurs will usually be portrayed in a swan-like posture when emerged, and will use their neck as a periscope when swimming underwater. According to biomechanical studies, they’d kept their neck straight to better plough the water, and used their flippers to literally “fly” underwater, even though the exact movement of the flippers is still uncertain (see also “Pliosaurs” below). Maybe plesiosaurs were among the most skilled swimming animals of all time. Like whales compared with dolphins, larger species should have been less-agile than the smaller ones. Some portrayals show plesiosaurs with a sort of fin at the end of their tail, but it’s only speculative. If really present, it acted only as a rudder, as plesiosaur’s tail was too weak to propel the animal.

The commonly shown species is ''[[http://en.wikipedia.org/wiki/Elasmosaurus Elasmosaurus]]''. It was one of the largest plesiosauroids, 40ft/13m long (like a grey whale), but since only a small portion of its length was of body, it weighed “only” 8-10 tons (like a large killer whale). The 20ft/7m long neck made more than half the entire length, and was actually longer than the body. Living in Late Cretaceous in the inland North-American Sea, the elasmosaur was discovered in the USA during the Bone-Wars. Its describer, Edward Cope, made an astounding mistake in its first attempt to rebuilt its skeleton (see UsefulNotes/PrehistoricLife). The prototypical ''[[http://en.wikipedia.org/wiki/Plesiosaurus Plesiosaurus]]'' was the first described plesiosaurian (1810s), even before ''Megalosaurus'' and ''Iguanodon''. First found in England, it was much smaller (16 ft long),earlier (first Jurassic), and much shorter-necked than ''Elasmosaurus''.

Like Plesiosauroids, Pliosauroids too were widespread throughout the Mesozoic, 218-65 mya. Both subgroups shared the same body plan, with rigid bodies, short tails, and the two pairs of powerful flippers--perhaps alternately-moved making a typical “double-wings” swimming effect (as seen in ''WalkingWithDinosaurs''). The difference stays in front of their shoulders. Pliosaurs had very short stocky necks, and their head was far bigger than an ''Elasmosaurus''. Their teeth were less-numerous, but much longer and stronger: like elasmosaurs, expect to see them visible when the mouth closed, even though they could have been hidden by lips in RealLife. Despite the resemblances, the head-anatomy of plesios and plios was the same. Both had eyes and nostrils placed above to see out of water when the remaining head was submerged. Both shared a singular trait: each nostril had two chambers like fish, possibly giving them a directional sense of smell. We don’t know if they passed more time near the surface or in the deeps, but some think pliosaurs were more deep-creatures than plesiosaurs.

Pliosaurs were variably-sized, some were not bigger than dolphins, but the biggest one are candidates for “the largest sea reptile” title – even though their size has often been exagerrated. Among the latter, ''[[http://en.wikipedia.org/wiki/Liopleurodon Liopleurodon]]'' and ''[[http://en.wikipedia.org/wiki/Kronosaurus Kronosaurus]]'', were among the top-predators of the Jurassic and early Cretaceous oceans respectively. Once extimated 16 m long (10 m are more likely), ''Kronosaurus'' is named from Cronus, a Greek goddity who [[IAmAHumanitarian devoured its own offsprings]] (Zeus and Poseidon among them). About the same length was the less-coolly named ''Liopleurodon'', virtually identical to the former but with less teeth. As is usual with marine superpredators, both are usually depicted as [[CarnivoreConfusion merciless ever-hungry]] [[PrehistoricMonster killing machines]].

Descended from a still-unknown land-living ancestor (remember ''every'' lineage of marine reptiles did descend from four-limbed terrestrial reptiles), Ichthyosaurs were the most marine of all marine reptiles and never came onto land, not even for laying their eggs. In fact, their young were born alive just like modern dolphins, as we can see in some fossils of mothers dead with their offspring ''just getting out of their body''. We now know that plesiosaurs also reproduced in the same way and probably never left the water either -- however, the scene of a long-necked plesiosaur which crawls on the seashore like a sea-lion is a [[RealityIsUnrealistic staple in artworks]]. Ichthyosaurs are extremely abundant in fossil record: several individuals are preserved with soft tissue and, sometimes, ''even the print of the whole body''. Thanks to the latter, we know they had a dorsal fin and a crescent-shaped caudal fin other than the four paired “flippers”. A strange thing is, unlike modern sharks, the backbone curved ''downwards'' at the tail level, and filled the lower lobe of the caudal fin, not the upper one.

Today, more updated ichthyosaurs are regular sights in dino-books. They’re very useful to show evolutive mechanisms, making a classic example of "convergent evolution" with fish and cetaceans. On the other hand, they are rarely seen in recent dino-stories, much less than the long-necked plesiosaurs. Maybe they are not that exotic-looking, or just not impressive enough to attract writers’ intrerest. The species shown is always ''[[http://en.wikipedia.org/wiki/Ichthyosaurus Ichthyosaurus]]'', because was the first discovered ([[OverlyLongGag in the 1810s. in England, before the “first known dinosaurs”]], and the prototype of the group. Being only 8/10 ft long in RealLife, expect to see it oversized and over-scary. And never mind that some other ichthyos (''[[UsefulNotes/PrehistoricLife Temnodontosaurus, Cymbospondylus, Shonisaurus]]''), being 25 ft long or more, could be very apt for the role. The absence of ''Shonisaurus'' is particularly strange: as large as a sperm-whale, it could be the biggest known sea-reptile.

Its “sail” substained by elongated vertebral spines has always been an headache for scientists. The classic theory consider it a thermoregulating device. Put against the solar rays it could have captures much heat like a solar panel; if put parallel to them, it was more like a radiator, dispersing heat. Considering its desertic habitat, this hypothesis still remains a good one. Other theories are mating or threat display, inter-specific identification, and so on. Maybe the sail served for all these purposes. Among external features, ''Dimetrodon'' could also have had some sparse hair, hints of auricles and maybe even proto-milk glands. These things are totally unsure, and given its primitiveness, are unlikely. The coloration is totally speculative--living in harsh habitat, it should be brownish like modern desert mammals, but its sail could have been vividly coloured and/or able to change colors for display purpose. Sadly, synapsid soft tissues are virtually unknown. No eggs or nests are known from the dimetrodont, and we don’t know if it was oviparous, or viviparous like modern mammals (if the latter is true, viviparity was achieved independently).

* They weren't either dinosaurs, nor were they birds. Further, they were not even the ancestors of any modern flier[[hottip:*:dinosaurs were]]: instead, they were only ''relatives'' of dinosaurs (and thus birds, of course).

Surprisingly, stock pterosaurs are ''not'' (necessarily) the biggest/coolest-looking ones --three out of five are not bigger than an eagle or a stork. Instead, they were among the very first scientifically-described kinds, in the XIX century. ''Pterodactylus'', ''Rhamphorhynchus'', and ''Dimorphodon'', [[hottip:*: The normally-sized ones]] were discovered in Europe ''before'' the 1820s (the decade in which the “first dinosaurs” were named). The last two were initially classified as “Pterodactylus” and recognized distinct only after the 1820s. With its 7 m/24 ft wide wingspan, ''Pteranodon'' was found in USA in the last quarter of the XIX century, during the “Bone Wars”. [[hottip:**: Oddly, it too was initially classified as ''Pterodactylus''.]] Its sheer size (“Whoa the biggest flier ever!) and its crest soon made it the new iconic pterosaur, and still preserves its status today.

''Pteranodon'' lived 86-84 million years ago on what were then the shorelines of Kansas and other midwestern US states. It had the typical traits of the most evolved pterosaurs, the Pterodactyloids aka “literal pterodactyls”. It had an elongated head, weak hindlimbs, only a hint of tail, and very long wings with a huge “wing-finger”, while the other digits were very small and maybe almost useless. It was one of the most specialized flying animals that ever lived, but very clumsy on land, where it arguably walked slowly on all fours.

The backwards-pointing crest is the most striking feature of ''Pteranodon''. It was laterally flattened in RealLife, but in media expect to see it with a conical shape, often resembling a ''horn''. The real purpose of this crest is still unclear. It is traditionally described as a sort of balancing-pole to better balance the long head, or as a rudder to maintain it stabilized during flight. However, this doesn’t explain why only males had such a big crest, while the females’ one was extremely shortened. Once was thought long- and short-crested individuals belonged to different species. [[hottip:*:An astounding thing is, short-crested pteranodonts are ''almost never'' shown even in documentary media!]] This bony protrusion could simply be a display device, like is hypothized as well for Stegosaur’s plates, Triceratops’ horns and frill, Spinosaurus “sail”, and so on. This could explain why the males’ one was so big compared with the females.

In RealLife, ''Pteranodon'' was substantially a giant pelican in behaviour. Its long toothless beak was useful to catch fish, and the shape of its lower jaws seem to show a sort of “pouch” to store fish in flight, even though this is not sure. If alive today, ''Pteranodon'' could not be that danger for us folks as shown everywhere in media. Weighing only about 20 kg [[hottip:**:Compared to body size pterosaurs were even lighter than birds, having totally hollow bones like straws. For example, the prehistoric vulture ''Argentavis'' had a similar wingspan of the pteranodont, but is extimated 80 kg.]], was too light to lift a 70 kg man up in the air. And if it really could have done so, certainly didn’t with its weak hindlimbs but with the mouth instead. Finally, since its beak was straight and smooth-edged, a child could easily have got out of it by wriggling.

Like ''Pteranodon'', ''Rhamphorhynchus'' tends to be portrayed incorrectly in fiction, often as big as a pteranodont or even bigger. Another classic mistake is to show rhamphorhynchs with flexible tails (a bit like what happens to “raptors”) and sometimes with ''triangular'' fins. Actually their tail was stiffened by bony tendons, and was a steering device during flight. [[hottip:*:It’s not to exclude that only males had the “fin”. If so, this thing could have been for display.]] Finally, a very Undead-Horse subtrope is to apply the “devilish” rhamphorhynchoid tail to [[RuleOfCool every]] [[TheyJustDidntCare other]] [[MixAndMatchCritter pterosaur]], expecially ''Pteranodon''. Actually pterodactyloid pterosaurs had stubby tails without distinction.

''Quetzalcoatlus'' was long described as similar to an upscaled ''Pteranodon''. Indeed, both animals had a long toothless beak and an atrophied tail. Some depictions show ''Quetzalcoatlus'' with a small cranial crest, others show it crestless. Compared to a pteranodont, ''Quetzalcoatlus'' had much longer/stronger hindlimbs, a bigger body, a longer/stiffer neck, and shorter/wider wings with the “hands” closer to the wingtips than to the shoulders. Its diet has long been an enigma (Fish? Small reptiles? Carrions?). In the 2000s, scientists re-studied its anatomy, and today ''Quetzalcoatlus'' is thought a mainly terrestrial animal, walking on its four long limbs, and eating small land critters like a stork. [[hottip:*:It’s worth noting that the terrestrial hypothesis was already postulated just after the first find, but initially not demostrated.]]

Similarly, these animals are often collectively referred to as "swimming dinosaurs", but this time they were ''not'' close relatives of true dinosaurs; some of them were not even related each other. If you'd like to see a seagoing dinosaur, watch ''[[EverythingsBetterWithPenguins March of the Penguins]]''.

Four main groups of sea reptiles can be recognized in media: Plesiosaurs, Ichthyosaurs, Mosasaurs, and Pliosaurs. In RealLife there were other sea-going reptiles in the Mesozoic, but being less-impressive than the former, they don’t gain much attention. (except for the giant turtle ''Archelon'', that shows up occasionally). As with most prehistoric animals, only the largest will be mentioned from each group: ''Elasmosaurus'' for Plesiosaurs, ''Liopleurodon'' for Pliosaurs, and ''Tylosaurus'' for Mosasaurs --with the exception of the Ichthyosaurs. Ichthyosaurs will be represented only by ''Ichthyosaurus'' which was actually small for the group, though that won't stop them writers from making it bigger. However, in old media ''Plesiosaurus'' is frequent as well, even though was a very small member of the eponymous group (but don’t worry: it is shown regularly oversized as well).

Interestingly, unlike dinosaurs, marine reptiles were ''already'' well-known to science at the beginning of the 19th century. Their fossil record is overall wealthier and better-preserved than that of the dinosaurs. Significantly, the very ''first'' “antediluvian” reptiles entered in narrative media were not dinosaurs, but the Ichthyosaur and the Plesiosaur which battle each other in the novel ''JourneyToTheCenterOfTheEarth'' written by Jules Verne in 1864. Both animals were enormously oversized and depicted in a ''very'' fanciful way: if you read the novel, you'll find them more like MixAndMatchCritter-related [[SeaMonster sea-monsters]] than their RealLife counterparts.The “ichthyosaur” is similar to a mixup of whales-crocodiles-dragons-snakes-whatnot, and has not the familiar fish-like shape of a RealLife Ichthyosaurus. The plesiosaur is a bit more realistic, but has a serpentine neck and the shell of a sea turtle. However, some of these errors are due to ScienceMarchesOn, as we’ll se in the single sections below.

Possibly thanks to Verne, the battle against prehistoric marine reptiles has become stock in paleo-art and pop-culture, just like its land-placed equivalent "Carnivorous vs Herbivorous Dinosaur". One of the opponents is always a long-necked Plesiosaur, while the other may alternate between a Mosasaur, an oversized ''Ichthyosaurus'', or a Pliosaur. In these portraits, ichthyosaurs, mosasaurs, and pliosaurs tend to be used indifferently, often confused each other and portrayed as generic “giant swimmers”.

Another long-standing cliche makes sea-reptiles the pterosaurs’ archenemies. You probably have already seen the scene of a "prehistoric leviathan" emerging abruptly from the surface of the sea, grabbing a giant flying reptile with its jaws (the victim is usually ''Pteranodon''), and dragging it underwater to eat it (DougalDixon once speculated that long-necked plesiosaurs would be soecialist seabird hunters if they survived to the present). In RealLife this could be possible only for the biggest mosasaurs and pliosaurs. Giant ichthyosaurs did roam the seas, but in their time pterosaurs were still ''very'' small. Even though giant plesiosaurs like ''Elasmosaurus'' could have interacted with giant pterosaurs, their small mouth was unable [[FridgeLogic to swallow whole]] [[GiantFlyer Giant Fliers]] like ''Pteranodon''. [[hottip:*:Note that ''Pteranodon'' bones have been discovered in the belly of a plesiosaur fossil, but they come from a small, female or juvenile pterosaur, not a gigantic male]].

Plesiosaurs (more correctly, plesiosauroids) are the most distinctive marine reptiles, and lived worldwide throughout the Mesozoic, 210-65 mya. With their long necks, massive body, short tails, small heads, and four paddle-like limbs, their look may recall that of a “flippered brontosaur”, but they were actually very different than a sauropod dinosaur. They were carnivorous like all known marine reptiles. With their small mouths, they arguably ate only small items, like fish, juvenile reptiles, or shellfish. Their hunting tecniques are still matter of discussion -- active hunting, ambush-predation, bottom-feeding or even partial filter-feeding are all possible. They had pointed teeth protruding from their jaws, but were perhaps covered by lips in the living animals. [[RuleOfCool For obvious reasons]], expect to see plesiosaurs with ever-visible teeth fitted outside their mouth, often oversized and more protruding than in RealLife, literally making a snake-like head.

The long-necked plesiosauroids belong to the Sauropterygian supergroup, which also includes the Pliosaurs (or Pliosauroids) and other less-known groups of sea-reptiles. Together, Plesiosauroids and Pliosauroids make the ''Plesiosauria'', aka “plesiosaurs” in broader sense, originated from the same common ancestor in the Triassic seas. Their relationship of Sauropterygians with modern reptiles has long been unclear. Once, they were placed with Ichthyosaurs in their own subgroup (see further), and not related with any still-living reptilian group. Today, plesiosaurs sensu lato (pliosaurs included) are thought not closely related to ichthyosaurs. They seem only loosely related with modern lizards, rather that with crocodiles and dinosaurs.

Despite this, Pliosaurs have been the least-portrayed group of sea-reptiles, and still remain mainly documentary-animals. The kronosaur has long been the most commonly shown pliosaur in books and documentaries until 1999, when a memorable appearance of an [[RuleOfCool extraordinarily oversized]] [[hottip:*: The fictional length 80ft/25m was based on misidentified bone fragments; in reality, the species maxed out at 25ft/7m long]] ''Liopleurodon'' on WalkingWithDinosaurs rapidly made it the new iconic member of the family (very similarly to ''Deinonychus'' à ''Velociraptor'' thanks to ''Film/JurassicPark''). In the show, an old male liopleurodon was described weighing 150 tons (a bit less than the Blue Whale) and [[UpToEleven the biggest predator of all time]]. In particular, the scene in which he pulls the ichthyosaur in pieces [[NightmareFuel disturbed many viewers]] (even though the sad final scene where he’s stranded and slowly dies gives it a bit of humanity). To give the idea about how the animal remained impressed in pop-consciousness: [[FollowTheLeader all successive depictions]] have shown Liopleurodons with the WWD blue-white color-patterns. [[hottip:**: For some reason, unlike dinosaurs and pterosaurs, marine reptiles are almost-always shown with dull colors even in modern portraits. However, they could have been very colorful like modern tropical seagoing animals.]] While WWD may have made ''Liopleurodon'' the Stock Pliosaur in place of ''Kronosaurus,'' CharlieTheUnicorn managed to bring it to the status of minor Internet meme.

Ichthyosaurs have the very evocative name of “fish-lizards”: they really resembled large fish in shape and swimming style, but recall modern dolphins as well thanks to their flippers and their long “nose”. Like fishes and unlike dolphins, they had ''four'' flippers (foreflippers were usually bigger) and an ''upright'' caudal fin. As a group, Ichthyosaurs were the most ancient marine reptiles, and were widespread from the Middle Triassic until the Late Cretaceous, 245-90 mya, but went extinct 25 million years before the mass-extinction. Once, ichthyosaurs, plesiosaurs and pliosaurs were put together in their own reptilian supergroup, the “Euryapsids”, unified by having a single pair of skull-openings on the top of the skull. Today, “euryapsids” are firmly put in the Diapsid supergroup (which also included dinosaurs, pterosaurs and all living reptiles except maybe turtles). Icththyosaurs were among the very first diapsids to have evolved: since they are not related with any modern animal group (thus preventing good comparisons), they still remains quite mysterious critters.

Descended from a still-unknown land-living ancestor (remember ''every'' lineage of marine reptiles did descend from four-limbed terrestrial reptiles), Ichthyosaurs were the most marine of all marine reptiles and never came onto land, not even for laying their eggs. In fact, their young were born alive just like modern dolphins, as we can see in some fossils of mothers dead with their offspring ''just getting out of their body''. We now know that plesiosaurs also reproduced in the same way and probably never left the water either---however, the scene of a long-necked plesiosaur which crawls on the seashore like a sea-lion is a [[RealityIsUnrealistic staple in artworks]]. Ichthyosaurs are extremely abundant in fossil record: several individuals are preserved with soft tissue and, sometimes, ''even the print of the whole body''. Thanks to the latter, we know they had a dorsal fin and a crescent-shaped caudal fin other than the four paired “flippers”. A strange thing is, unlike modern sharks, the backbone curved ''downwards'' at the tail level, and filled the lower lobe of the caudal fin, not the upper one.

Their eyes were noticeably large for good vision; most portraits show ichthyosaurs with round pupils and no eyelids like a typical fish. Skull nasal openings were just in front of the eyes, but the nostrils could have been on the head-top. Their skin was smooth and hydrodynamic like a dolphin, as shown in fossil prints. The mouth was usually filled with acute teeth: most ichthyos were fish-eaters, but also ammonites and other shellfish were in their menu. We don’t know what amount of time they passed underwater: maybe they could extract some oxygen directly from the water like modern sea-turtles, but certainly did breath regularly like every reptile. The resemblance with dolphins means artists classically show ichthyosaurs jumping out of water in a dolphinish style, but this is not proven. Unusually for extinct reptiles, “Fish-lizards” often escape the fate to be described as “monsters”… at least in modern docu-media. [[ScienceMarchesOn Originally]], ichthyosaurs were depicted more crocodile- or mosasaur-like, with no caudal or pectoral fins. The famous “ichthyosaur” in Verne’s novel is just based on this early interpretation. Several other fictional ichthyosaurs [[FollowTheLeader have then been inspired by the original]].

The most recent group of Mesozoic sea-reptiles, Mosasaurs lived worldwide in the Late Cretaceous, at the end of the Age of Dinosaurs. They replaced Ichthyosaurs and coexisting with the last Plesiosaurs. While Ichthyos and Plesios were not closely related with any modern reptile, Mosasaurs are the only prehistoric animals which literally deserve the title of "giant lizards". They belong to the [[http://en.wikipedia.org/wiki/Squamata Squamates]], the group containing modern lizards and snakes [[hottip:*:Never forget snakes ''are'' legless lizards just as birds are flying dinosaurs]], and were closely related to modern snakes and monitor-lizards. Indeed, due to their elongated shape, they have often been compared with the legendary "sea-serpent", and often depicted with a speculative dragon-like crest running along their back in much old paleo-art.

Mosasaurs’ head was similar to modern lizards but with a longer snout. Like the latter, they’d have had fleshy lips. Like modern snakes, their mouth had a notably loose hinge between the jaws: this allowed mosasaurs to swallow big items without tearing them in pieces. The teeth were conical, the upper ones placed in two rows on each half-jaw, again like modern snakes and monitors. According to stomach contents, Mosasaurs were very generalist feeders: fish, sharks, squids, pterosaurs, early birds like ''[[UsefulNotes/PrehistoricLife Hesperornis]]'' and even smaller mosasaurs have been found. [[hottip:*: This ''doesn’t necessarily mean'' they were cannibals, though: the preyed mosasaurs could be from different species than their predators. After all, modern orcas do eat smaller dolphins]]. We don’t known if mosasaurs had a forked tongue and ever-open eyes like many modern squamates, nor if they had heat-sensors like some boas and rattlesnakes: these things usually don’t preserve in fossil record.

Like pliosaurs and ichthyosaurs, Mosasaurs are a staple in documentaristic media, but are not-so-common in stories. Most “giant leviathans” with huge jaws seen in fiction tend to be generic monsters a-la-Verne, rather than precise kinds of sea-reptiles. And don’t exclude to see mosasaurs confused with [[SomewhereAPalaeontologistIsCrying sharks]]. ''[[http://en.wikipedia.org/wiki/Tylosaurus Tylosaurus]]'' and the namesake ''[[http://en.wikipedia.org/wiki/Mosasaurus Mosasaurus]]'' are the stock members of the mosasaur family: needless to say, they're among the largest, up to 10-15 m long. The former was found during the “Bone Wars” in USA. The latter has a much more fascinating story. Found in the Netherlands near the Mosa river at the end of the 1700 (hence its name), ''Mosasaurus'' was not only the first sea reptile ever discovered, but the second fossil recognized by science as belonging to a Mesozoic reptile, after ''Pterodactylus''. See also UsefulNotes/PrehistoricLife.

Not all Mesozoic reptiles were exotic critters, however. ''Archelon'' was just what it seems: just a sea-turtle. But it fits perfectly the subtrope “Everything was huge at dinosaur times”: it’s the largest known fossil turtle--4 m/13 ft long and weighing some tons, ''Archelon'' was 2-3 times bigger than the biggest modern turtle (the [[http://en.wikipedia.org/wiki/Dermochelys_coriacea Leatherback turtle]], confirming TurtlePower is TruthInTelevision. However, it was not the ancestor of modern sea-turtles: it pertained to a different lineage, the Protostegids, which went extinct along the other giant reptiles at the end of the Cretaceous. Its name is a {{Portmanteau}} of “arche” (primeval) and “chelon” (turtle).

''[[TaxonomicTermConfusion Technically]]'' they are not even "reptiles".

Being a very early mammal-ancestor, ''Dimetrodon'' has still a lizardy shape, with long tail, long body, splayed legs, and skull with a small braincase. Fossil prints show a lizard-like gait. Other traits, on the other hand, were quite mammalian: a laterally-flattened trunk (not wider-than-taller like most modern reptiles); a solid skull with one single pair of temporal opening placed near the maxillary hinge (the so-called “synapsid” condition also seen in mammals, us humans included); and differently-shaped teeth--“Dimetrodon” just means “teeth with two lengths”. Even though all teeth were conical, the anterior ones were small and crammed together like incisors, while the longest teeth were in the place mammals have usually their canines. Behind them, the posterior teeth were small and not apt for chewing food unlike our molars, but are somewhat analogue to those seen in primitive insectivorous mammals. More evolved synapsids like ''Cynognathus'' achieved a clearly mammalian anatomy, with more erect limbs, shorter tails, larger brains, and teeth very similar to mammals (see UsefulNotes/PrehistoricLife).

''Dimetrodon'' is usually described as the top-predator of its time, shown hunting early “amphibians” like ''Eryops'', ''Diplocaulus'', ''Seymouria'' etc., as well as what could be called its [[NonIdenticalTwins Non-Identical Twin]], ''Edaphosaurus''. Its crest, its (apparently) [[ReptilesAreAbhorrent reptilian look]] and the meat-eating attitude makes the dimetrodon a predestined victim of DinosaursAreDragons and PrehistoricMonster both in Fiction and in docu-media. However, if compared with other famous prehistoric animals, ''Dimetrodon'' could appear rather [[{{Narm}} narmy]] in comparison. If we imagine a battle against a Tyrannosaurus/Deinosuchus/Smilodon/Mosasaur, the primitive and relatively small dimetrodont would always result the loser--this could also be true when put against modern predators (lions, kodiak-bears, Nile crocs etc), as well as most ancient and modern giant herbivores. But in Permian landscapes, ''Dimetrodon'' was still faster and more powerful than every other land animal, definitively debunking the {{Narm}} thing.

Although "saber-tooths" belongs to the "cat family", they are in a separate branch of that clade compared to modern felines; thus, the popular denomination "Sabertooth tiger" is not correct at all. The "tiger" thing means that ''Smilodon'' is often heard roaring just like an actual tiger or a lion, though only the big cats of the genus ''[[PantheraAwesome Panthera]]'' (that is, Lion, Tiger, Jaguar and Leopard) could make roars thanks to the structure of their larynxes unique of this group. This depiction is, however, vindicated by science, as the structure of the small bones in its mouth are set up for making a sort of roar.

''Quetzalcoatlus'' was long described as similar to an upscaled ''Pteranodon''. Indeed, both animals had a long toothless beak and an atrophied tail. Some depictions show ''Quetzalcoatlus'' with a small cranial crest, others show it crestless. Compared to a pteranodont, ''Quetzalcoatlus'' had much longer/stronger hindlimbs, a bigger body, a longer/stiffer neck, and shorter/wider wings with the “hands” closer to the wingtips than to the shoulders. Its diet has long been an enigma (Fish? Small reptiles? Carrions?). In the 2000s, scientists re-studied its anatomy, and today ''Quetzalcoatlus'' is thought a mainly terrestrial animal, walking on its four long limbs, and eating small land critters like a stork. [[hottip:*:It’s worth noting that the terrestrial hyp was already postulated just after the first find, but initially not demostrated.]]

Its “sail” substained by elongated vertebral spines has always been an headache for scientists. The classic theory consider it a thermoregulating device. Put against the solar rays it could have captures much heat like a solar panel; if put parallel to them, it was more like a radiator, dispersing heat. Considering its desertic habitat, this hyp still remains a good one. Other theories are mating or threat display, inter-specific identification, and so on. Maybe the sail served for all these purposes. Among external features, ''Dimetrodon'' could also have had some sparse hair, hints of auricles and maybe even proto-milk glands. These things are totally unsure, and given its primitiveness, are unlikely. The coloration is totally speculative--living in harsh habitat, it should be brownish like modern desert mammals, but its sail could have been vividly coloured and/or able to change colors for display purpose. Sadly, synapsid soft tissues are virtually unknown. No eggs or nests are known from the dimetrodont, and we don’t know if it was oviparous, or viviparous like modern mammals (if the latter is true, viviparity was achieved independently).

Not all Mesozoic reptiles were exotic critters, however. ''Archelon'' was just what it seems: just a sea-turtle. But it fits perfectly the subtrope “Everything was huge at dinosaur times”: it’s the largest known fossil turtle--6 m/20 ft long and weighing some tons, ''Archelon'' was 2-3 times bigger than the biggest modern turtle (the [[http://en.wikipedia.org/wiki/Dermochelys_coriacea Leatherback turtle]], confirming TurtlePower is TruthInTelevision. However, it was not the ancestor of modern sea-turtles: it pertained to a different lineage, the Protostegids, which went extinct along the other giant reptiles at the end of the Cretaceous. Its name is a {{Portmanteau}} of “arche” (primeval) and “chelon” (turtle).

Descended from monitor-like animals, Mosasaurs often reached gigantic sizes, but exaggerations tend to be common. Some source talk about 20 m long animals, even though most giant mosasaurs were probably no more than 10 m long. With their slender bodies, they were also less-heavy than the robust plesiosaurs and pliosaurs. To be more hydrodinamic, they could have lost the original lizard-scales and developed a smooth skin-texture, like ichthyosaurs and plesiosaurs. Their tail was long and laterally-flattened: unlike plesiosaurs, they swum in a crocodilian-manner swinging their tail side-to-side. Since many modern snakes and lizards are ovoviviparous (that is, produce eggs that hatch inside the mother’s body), this could be true also for mosasaurs. In this case, they hadn’t to come ashore to reproduce, and maybe lived entirely in water. As their limbs were fin-like, this could be a proof. All marine-reptiles described here obtained their flipper-like limbs in the same way of modern cetaceans, embedding their original digits in one single fleshy mass, and enormously multiplying the number of phalanxes (ichthyosaurs took this to an extreme).

Their eyes were noticeably large for good vision; most portraits show ichthyosaurs with round pupils and no eyelids like a typical fish. Skull nasal openings were just in front of the eyes, but the nostrils could have been on the head-top. Their skin was smooth and hydrodinamic like a dolphin, as shown in fossil prints. The mouth was usually filled with acute teeth: most ichthyos were fish-eaters, but also ammonites and other shellfish were in their menu. We don’t know what amount of time they passed underwater: maybe they could extract some oxygen directly from the water like modern sea-turtles, but certainly did breath regularly like every reptile. The resemblance with dolphins means artists classically show ichthyosaurs jumping out of water in a dolphinish style, but this is not proven. Unusually for extinct reptiles, “Fish-lizards” often escape the fate to be described as “monsters”… at least in modern docu-media. [[ScienceMarchesOn Originally]], ichthyosaurs were depicted more crocodile- or mosasaur-like, with no caudal or pectoral fins. The famous “ichthyosaur” in Verne’s novel is just based on this early interpretation. Several other fictional ichthyosaurs [[FollowTheLeader have then been inspired by the original]].

Ichthyosaurs have the very evocative name of “fish-lizards”: they really resembled large fish in shape and swimming style, but recall modern dolphins as well thanks to their flippers and their long “nose”. Like fishes and unlike dolphins, they had ''four'' flippers (foreflippers were usually bigger) and an ''upright'' caudal fin. As a group, Ichthyosaurs were the most ancient marine reptiles, and were widespread from the Middle Triassic until the Late Cretaceous, 245-90 mya, but went extinct 25 years before the mass-extinction. Once, ichthyosaurs, plesiosaurs and pliosaurs were put together in their own reptilian supergroup, the “Euryapsids”, unified by having a single pair of skull-openings on the top of the skull. Today, “euryapsids” are firmly put in the Diapsid supergroup (which also included dinosaurs, pterosaurs and all living reptiles except maybe turtles). Icththyosaurs were among the very first diapsids to have evolved: since they are not related with any modern animal group (thus preventing good comparisons), they still remains quite mysterious critters.

Ichthyosaurs have the very evocative name of “fish-lizards”: they really resembled large fish in shape and swimming style, but recall modern dolphins as well thanks to their flippers and their long “nose”. Like fishes and unlike dolphins, they had ''four'' flippers (foreflippers were usually bigger) and an ''upright'' caudal fin. As a group, Ichthyosaurs were the most ancient marine reptiles, and were widespread from the Middle Triassic until the Late Cretaceous, 245-90 mya, but got extinct 25 years before the mass-extinction. Once, ichthyosaurs, plesiosaurs and pliosaurs were put together in their own reptilian supergroup, the “Euryapsids”, unified by having a single pair of skull-openings on the top of the skull. Today, “euryapsids” are firmly put in the Diapsid supergroup (which also included dinosaurs, pterosaurs and all living reptiles except maybe turtles). Icththyosaurs were among the very first diapsids to have evolved: since they are not related with any modern animal group (thus preventing good comparisons), they still remains quite mysterious critters.

Another long-standing cliche makes sea-reptiles the pterosaurs’ archenemies. You probably have already seen the scene of a "prehistoric leviathan" emerging abruptly from the surface of the sea, grabbing a giant flying reptile with its jaws (the victim is usually ''Pteranodon''), and dragging it underwater to eat it. In RealLife this could be possible only for the biggest mosasaurs and pliosaurs. Giant ichthyosaurs did roam the seas, but in their time pterosaurs were still ''very'' small. Even though giant plesiosaurs like ''Elasmosaurus'' could have interacted with giant pterosaurs, their small mouth was unable [[FridgeLogic to swallow whole]] [[GiantFlyer Giant Fliers]] like ''Pteranodon''. [[hottip:*:Note that ''Pteranodon'' bones have been discovered in the belly of a plesiosaur fossil, but they come from a small, female or juvenile pterosaur, not a gigantic male]].

Despite this, Pliosaurs have been the least-portrayed group of sea-reptiles, and still remain mainly documentary-animals. The kronosaur has long been the most commonly shown pliosaur in books and documentaries until 1999, when a memorable appearance of an [[RuleOfCool extraordinarily oversized]] [[hottip:*: The fictional length 80ft/25m was based on misidentified bone fragments; in reality, the species maxed out at 25ft/7m long]] ''Liopleurodon'' on WalkingWithDinosaurs rapidly made it the new iconic member of the family (very similarly to ''Deinonychus'' à ''Velociraptor'' thanks to JurassicPark). In the show, an old male liopleurodon was described weighing 150 tons (a bit less than the Blue Whale) and [[UpToEleven the biggest predator of all time]]. In particular, the scene in which he pulls the ichthyosaur in pieces [[NightmareFuel disturbed many viewers]] (even though the sad final scene where he’s stranded and slowly dies gives it a bit of humanity). To give the idea about how the animal remained impressed in pop-consciousness: [[FollowTheLeader all successive depictions]] have shown Liopleurodons with the WWD blue-white color-patterns. [[hottip:**: For some reason, unlike dinosaurs and pterosaurs, marine reptiles are almost-always shown with dull colors even in modern portraits. However, they could have been very colorful like modern tropical seagoing animals.]] While WWD may have made ''Liopleurodon'' the Stock Pliosaur in place of ''Kronosaurus,'' CharlieTheUnicorn managed to bring it to the status of minor Internet meme.

''Pteranodon''’s nifty crest on its skull, along with the fact to have holded the size-record for almost a century, has made it THE pterosaur in popular imagination. Its iconic status among pterosaurs coud be partially justified. It’s not only one of the first discovered pterosaurs, but perhaps also the most common in fossil record. Hundreds of specimens are known, while most other pterosaur kinds are much, much rarer, often known from a single individual. The vast majority of Pteranodons belong to the species all people know, ''Pteranodon longiceps''. Another species is even bigger and cooler-looking, but its fossils are much rarer: ''[[UsefulNotes/PrehistoricLife Pteranodon sternbergi]]''.

Possibly thanks to their dinosaurian-look and the association with snakes, Plesiosaurs have been the most iconic and depicted sea reptiles in media. Like dinosaurs and pterosaurs, expect to see them as [[DinosaursAreDragons scary monsters]] with an [[EverythingTryingToKillYou killing attitude towards humans]]. If alive today, even the biggest Elasmosauruses wouldn’t be more aggressive than most whales (although they could unintentionally capsize your tiny boat or raft). And every time a plesiosaur shows up, ''someone'' will bring up the [[StockNessMonster Loch Ness Monster]].