What you wanted to know about plesiosaurs. If you can't find the answer to a burning question, or if you have additional questions or comments of your own, e-mail me. Your question may be incorporated into the next version of this FAQ.
This FAQ is still in its early stages. I would have wanted to present it in a more complete form, but one of my visitors asked me when I was going to put it up. I have to confess at this point that finding plesiosaur info on the Web is even more difficult than for plesiosaurs, which in turn plays second fiddle to dinosaurs. Anyway, as I get more info, I'll add it to this FAQ. In the meantime, please bear with me and the errors on this page (which I am now correcting).
Marine reptiles (Shonisaurus, Liopleurodon, Elasmosaurus, Archelon)
Our featured artist for July 2005 is John Bindon. He a gallery of prehistoric animal illustrations including this masterpiece of the largest species of major marine reptile groups (ichthyosaurs, plesiosaurs (pliosaurs and elasmosaurs), and turtles). Visit his website Bindon Illustrations.
Q: What are plesiosaurs?
A: Plesiosaurs are a group of marine reptiles that populated the seas while the dinosaurs dominated the land. To be more precise, they are classified in a group called the Sauropterygia, which is in turn a subgroup of the somewhat problematic Euryapsida. "Plesiosaur" comes from two Greek words that together mean "near lizard." This name was given to them after the bones of the first specimen to be discovered were described as resembling those of true lizards.
Q: How is the word "plesiosaur" pronounced?
A: Ple-sio-sar. Sometimes ples-yo-sar, plee-sio-sar or plees-yo-sar is heard; they don't seem to bother paleontologists.
Q: When and where did they live?
A: The earliest plesiosaurs appeared sometime in the Late Triassic, about 230 million years ago, about the same time as the dinosaurs . They then lived on through the Jurassic until the very end of the Cretaceous, when, together with the dinosaurs and a host of other plants and animals, they died out 65 million years ago. Plesiosaur remains have been found in all the continents including Antarctica.
The Mesozoic Era time scale
Q: Were they the first marine reptiles?
A: No. Other reptiles had already preceeded them. The earliest known
predominantly aquatic (but not necessarily marine) reptiles were the mesosaurs (or "middle lizards"), small (30 cm) creatures with webbed feet, finned tails and needle-like teeth. They appeared before the Mesozoic Era, in the Permian Period of the Paleozoic era. After their extinction in the middle of that period, there remained a long gap before any major group of reptiles took to the water. In the Triassic Period, several groups of sea-going euryapsids appeared, such as the dolphin-like ichthyosaurs ("fish lizards," a very appropriate name), the somewhat stocky placodonts ("plated tooth"), some of which bore uncanny resemblances to turtles in their possession of shells, and the long-necked nothosaurs. It was from a nothosaur-like ancestor that plesiosaurs evolved.
Q: When were they first discovered?
A: The first well-preserved plesiosaur fossil was discovered in 1824 by the British fossil collector Mary Anning.
Q: How did plesiosaurs originate?
A: As mentioned previously, plesiosaurs evolved from a nothosaur-like ancestor. Nothosaurs, with their webbed feet and comparatively sturdy limbs, probably still spent a lot of time on land and were hence amphibious in habits, like marine iguanas and seals are today.
Q: Aren't they true dinosaurs?
A: Although they lived at the same time as the dinosaurs, they, as euryapsid reptiles, were only distantly related to dinosaurs. (This is also the case for the other marine euryapsids, naturally). It is a common misconception that all "reptiles" that lived during the Mesozoic were dinosaurs, something some badly written books on fossils perpetuate.
Q: What does the plesiosaur family tree look like?
A: There are two major groups of plesiosaurs: one group had the classic small head on a long, serpentine neck. This is the plesiosaurs proper. From the plesiosaurs evolved a family known as the cryptocleidids. The other group had large heads on short necks. This is the pliosaur family. It appeared later than the plesiosaur family in the Early Jurassic. A family of extra-large plesiosaurs, the elasmosaurs with spectacularly long necks, appeared in the Cretaceous.
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The classification of the sautopterygia (plesiosaurs and nothosaurs). |
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This figure shows the traditional classification of plesiosaurs and their relatives the nothosaurs. |
This figure shows a different classification of plesiosaurs and their relatives the nothosaurs by Robert Bakker. |
Q: Were plesiosaurs good swimmers?
A: It is presumed that they were. After all, they were highly adapted to an aquatic
existence.
Q: How did they swim?
A: Nobody knows exactly how they swam. Obviously, of course, they had to use their limbs for paddling and steering. The problem lies in the form of the stroke that they used. Plesiosaurs have no living analogs for comparison. Ichthyosaurs surely swam like fish, with side-to-side undulations of their bodies; marine turtles and crocodiles still exist, so recreating the swimming motion of their extinct relatives is no problem. The plesiosaur has often been described as "a turtle with a snake through it." To date, three theories have been put forward as to how they paddled.
Q: Were they good swimmers?
A: The long-necked species probable weren't very good swimmers as their necks presented hydrodynamic problems. The short-necked species, with their tapered heads, must have been as proficient as seals and penguins.
Q: What other adaptations did they evolve?
A: The plesiosaur body was highly adapted to a marine existence. Improving over the finned feet of their nothosaur ancestors, plesiosaurs had well-developed flippers. In some species the digits sported extra joints (hyperphalangy) to increase the flexibility. The body is rather flattened dorso-ventrally, with abdominal ribs (gastralia) supporting the front of the trunk and chest.
Q: What did they look like?
A: No one knows exactly what they looked like; to date, no plesiosaur fossil has preserved the coloring or imprint of their skin. It is presumed that they must have have smooth skin to streamline their bodies. As for coloring, it is likely that, like many whales and sharks, plesiosaurs had skin in varying shades of gray, a color that enables them to blend to some extent with their surroundings. Famed paleontologist and illustrator Robert T. Bakker portrayed them in a February 1994 Discover article with fins at the ends of their tails.
Q: Could they have crawled on land?
A: Possible but it seems difficult. Their limbs appear to be too weak to support their weight for any appreciable length of time. Possibly if they were beached on the shore they can haul themselves back into the water. Of course, if they laid eggs on land they had to crawl on land, like sea turtles do today.
Q: What did they eat?
A: Plesiosaurs had a variety of prey to choose from. During the Jurassic, ammonites, distant relatives of the chambered nautilus, populated the seas. They were joined by belemnites, which were closer to squid. Osteichthyian (bony) fish started to diversify in the Jurassic and especially during the Cretaceous. Plesiosaur teeth and jaws are believed to be strong enough to pierce the shells of the ammonites.
The pliosaurs, with their huge heads, appear to have been the top predators of their time. No other predators approached the size that they attained; plesiosaurs, marine crocodiles, mosasaurs (marine lizards), and sharks all took a back seat to them. There were gigantic ichthyosaurs, such as the 15-meter
Shunosaurus and a more recent find which may have been 23 meters long (based on a 5 meter-long skull); these monstrous creatures, however, died out long before pliosaurs appeared, so gigantic ichthyosaurs and plesiosaurs did not live side-by-side.
Q: How did they raise their young?
A: Although no verifiable plesiosaur eggs have been found, it is presumed that they were oviparous, just like living archosaurs, birds and crocodiles.
Q: What is the oldest known plesiosaur?
A: The oldest known true plesiosaurs come from the upper Triassic Rhaetic of Southern England.
Q: What is the smallest known plesiosaur?
A: This would be a juvenile of the genus Plesiosaurus.
Q: What is the largest known plesiosaur?
A: The largest long-necked plesiosaur is the Late Cretaceous Elasmosaurus. It reached a length of 13 meters, have of which was taken up by the neck. This genus had the most number of cervical (neck) vertebrae of any animal, living or extinct: 76. The largest pliosaur is possibly
Pliosaurus. A jaw which may belong to an individual of this genus measures over 3 meters, which would give a projected body length of 15 meters. Meantime, isolated teeth and vertebrae found in the Oxford Clay of England may have come from an animal over 20 meters long. I was told that my previous reference,
Kronosaurus, another denizen of the Late Cretaceous seas found in Australia, had been reconstructed with its 12
meter length exaggerated.
Q: Could even larger plesiosaurs be lying in the ground waiting to be discovered?
A: Theoretically, yes. Despite the breathtaking sizes of Elasmosaurus and
Pliosaurus, they still fall short of the maximum sizes attained by sharks (the whale shark, at 18 meters), and whales (the blue whale, at 30 meters). It's not unreasonable to assume that they couldn't attain such sizes, if conditions were favorable.
Q: What parts of the world harbor large collections of plesiosaurs fossils?
A: The Oxford Clay of England hosts the most abnudant collection of plesiosaurs, with dozens of complete specimens and thousand of isolated bones.
The Late Cretaeous Niobrara Chalk in Kansas has yielded fossils of plesiosaurs and other marine reptiles. It once comprised part of the great inland sea that inundated the center of North America.
Q: In what TV shows did plesiosaurs appear in?
A: Unfortunately, I'm not aware of any TV show that did feature plesiosaurs. I don't recall an episode in the 1970's Land of the Lost where they appeared at all.
Q: Was the creature in the movie Loch Ness a plesiosaur?
A: I think it was meant to be. I haven't watched the movie (yet) so I can't answer with a definite yes. From the trailers that I have seen, though, yes, it does seem to be one.
Q: Did they appear in Jurassic Park and it's sequels
The Lost World and Jurassic Park III?
A: Not at all. Neither Michael Crichton (the book author) nor Steven Spielberg (the movie director) used plesiosaurs. Rumors go that they will finally appear in
Jurassic Park IV.
Q: In what other movies did plesiosaurs make an appearance?
A: Loch Ness is the one major movie where the title character is a plesiosaur.
In the original King Kong, a plesiosaur is seen attacking and eating a couple of sailors who are poling a raft. (Thanks to Robert Krampf of Robert Krampf's Science Shows at
http://www.krampf.com for this info.)
If you know of any others, I'd appreciate it if you tell me.
Q: Are the TV/movie portrayals of plesiosaurs scientifically accurate?
A: As there are so few movies and TV shows featuring plesiosaurs that I am aware of, I can't answer this question yet.
Q: Are there any documentaries about plesiosaurs?
A: The BBC and Discovery Channel's Walking With... series
included a single episode about the most dangerous seas in prehistory, and the
Late Cretaceous segment showed pliosaurs alongside other marine animals.
Q: Are there any books specific to plesiosaurs?
A: Despite searching the Net, I haven't found a single book written specifically about plesiosaurs. There are books written about the Loch Ness monster, but these do not, contrary to what many people believe, prove that it is a plesiosaur (more on this below). There is one book available at
Amazon.com, but it is not specific to plesioaurs and deals with other marine reptiles as well.
Prehistoric Marine Reptiles: Sea Monsters During the Age of Dinosaurs by Judy A.
Massare.
Q: Are there any articles in popular magazines about plesiosaurs?
A: The February 1994 issue of Discover has a cover story by Robert Bakker on extinctions in the marine environment at the end of the Jurassic and Cretaceous. In it he discusses his theory that true long-necked plesioaurs died out at the end of the Jurassic and were replaced by the pliosaur-derived elasmosaurs.
Q: Are there any articles in popular magazines about plesiosaurs?
A: The February 1994 issue of Discover has a cover story by Robert Bakker on extinctions in the marine environment at the end of the Jurassic and Cretaceous. In it he discusses his theory that true long-necked plesioaurs died out at the end of the Jurassic and were replaced by the pliosaur-derived
elasmosaurs.
This is where I present information about sightings and even captures of alleged plesiosaurs, as well as a brief piece about that most famous creature of all, the Loch Ness Monster. Unfortunately, I haven't filled this up yet.
Of all the monsters and long-lost creatures that are alleged to have been sighted, the one that has persisted the most and that has turned up the most number of times in the most number of places around the world is the plesiosaur. Practically every year the media reports the discovery of a plesiosaur in this lake or captured by trawlers in that sea. In spite of the rash of reports, and the enthusiasm of the discoverers (as well as the general public eager to make speculations), not one single case has been definitively confirmed to be that of a plesiosaur. Critics who allege that scientists are engaged in cover-up's (conspiracy theory, anyone?) have got the facts wrong. It is from personal experience whereby I learned that, in many cases, the written accounts are incomplete and often leave out the final conclusions of the experts as to the identity of creatures whose remains have been recovered. Questions regarding the identity are thus left open to speculation and foster a pack of rumors and guesses. I've lamented this during open season when an alleged plesiosaur was discovered washed-up on the shore of a Philippine island on December 1996. I'll tell the tale in due time. Meanwhile, I'll be posting other alleged sightings here.
The April 1998 issue of Discover magazine has a story about a creature, an alleged New England counterpart to the famed Loch Ness monster of Scotland, that is rumored to be a plesiosaur.
Q: Where can I find other sites about plesiosaurs?
A: Visit the following web sites:
University of California Museum of Paleontology. The museum is located at the Berkeley campus and sports an extensive collection of verterbate fossils (including plesiosaurs).
Plesiosaur introduction from Enchanted Learning. This site is geared towards children, but you'll still find stuff useful for older kids.
Oceans of Kansas. This site by Mike Everhart describes the fossils recovered from rocks that once lay in the Niobrara Sea in the Cretaceous Period. One page is devoted to plesiosaurs. A recent update recounts the successful dig with the Cincinnati Museum for an elasmosaur in the Pierre Shale of western Kansas.
Kheper - Metamorphosis and Evolution home page. Alan Kazlev's website deals not only with the scientific aspect of evolution, but also delves a bit into metaphysics, fantasy and mythology. One page is about plesiosaurs.
Plesiosaur.com. This is a comprehensive site by Richard Forrest, who sent me several corrections and additions.
Q: Are there exhibits featuring plesiosaurs?
A: Many museums around the world include a collection of plesiosaurs. Here are some of them. (Yes, the list is American in scope, but I'm in the process of adding other links.)
University of California Museum of Paleontology. This is at the Berkeley campus.
Peabody Museum. Located at Yale University, it houses several specimens of plesiosaurs.
American Museum of Natural History. The newly refurbished Hall of Vertebrate Origins offer visitors an exhibit arranged according to the latest interpretations of the vertebrate family tree.
The list of shows, movies, books, magazines, museums and exhibits is hardly exhaustive. I'm sure there are other stuff out there that merit attention. If you know of any, please inform me so that I may add them to this list.
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