|PLESIOTURTLE by Thomas Finley|
Imagine yourself a passenger on a time machine that suddenly deposits you in a foliage covered jungle swamp on the edge of a lake. A quick glance around and you are taken aback by the sheer number and variety of crocodilian residents floating about the reeds edge, eyes above water, lurking silently. Suddenly, an explosion of foam and water by the shoreline and a 40 foot monster called Purussaurus leaps onto land and takes down a 1000 pound herbivore. Elsewhere out on the lake, huge domed objects, the size of a mini-van, break the water's surface and cruise along, looking much like the famous Nessy hump shaped back you've heard about so many times. Up on shore, 15 foot tall creatures, standing bipedally are stripping the leaves off the trees.
If this sounds like a typical Jurassic day, you may be surprised to know that the scene described took place just 8 million years ago in Urumaco, South America, some 55 million years after the demise of the Dinosaurs.
Every so often, Paleontologists will hit the jackpot and make totally unexpected, monumental discoveries. Such was the case in the summer of 1972, when a Harvard paleontological expedition working in post Tertiary deposits of northern Venezuela dug up the remains of several huge fossil turtles. One of these turtles was bigger than any still living Chelonian and eventually proved to be the largest turtle ever recovered, even bigger than the previous champion giant, the Cenozoic oceanic Archelon.
Of the several new turtle species, team expert Roger Wood determined that the biggest one recovered existed fairly recently, swimming in the Venezuelan lakes, rivers and swamps perhaps up to just a few million years ago. This giant, aptly named Stupendemys Geographicus was a Miocene/Pliocene, fresh water aquatic turtle of gigantic size. The shell alone was estimated to be nearly eleven feet long !
The team uncovered an almost complete carapace, along with partial fragments. The shell was unearthed in an upside down position and detailed examination of the scute arrangement (shell pattern) led Wood to the conclusion that this was of the super-family Pelomedusidae, a type of Pleurodira. Pleurodiras are the sub-order of the order of turtles we know best here in North America, the Cryptodiras. Pleurodiras are also known as "side-necked turtles," because they retract their necks into their shells by folding it over onto itself, unlike the direct retraction method used by the Cryptodiras. Pleurodiras at one time were the dominant order, having worldwide distribution, but today are only found south of the equator. They are the sub-order responsible for the snake neck turtles (Chelidae), which include what is commonly referred to as one of the world's weirdest animals, the Mata Mata Turtle.
|Different neck retraction of the 2 orders.|
This uniqueness of Pleurodiras can be attributed to the long term isolation of Australia and surrounding islands from the rest of the world, as well as South America and Africa, to a lesser degree. Thus the most recent evolutions of the Pleurodiras took a different route than their northern counterpart Cryptodira since being isolated by continental drift, some 30 to 60 million years ago.
|Pleuridirad Snake Neck Turtle with Mata Mata to the right|
Despite physical similarities with it's extant relative, Podocnemis, the size of Supendemys was beyond immense, perhaps more than 100 times larger than the largest currently known South American Pleurodira. Along with the shell, some fragments of the plastron were recovered along with a massive, hulk-buster humerus bone that Wood speculated was most likely hinged into a huge modified leg/paddle, a feature found on the modern day Carretochelys, a small Indonesian fresh water turtle quickly approaching extinction at the hand of man.
|Pig Nose Turtle (Carretochelys) lives in fresh water, has fins and swims fast !|
|Stupendemys Geographicus showing recessed nuchal at top of shell|
Stupendemys had features that resembled modern Pelomedusids but also had different features as well. Enough in fact for Wood to describe it as "aberrant." Other unusual anatomic differences from modern peliomedusids include the placement of the glenoid (arm) socket, which faces forward rather than laterally like the modern podocnemis exspansa. This hints at the strong possibility that the animal did have fins or paddles, swimming via a modified breast-stroke.
|Possible powerful huge finned Stupendemys|
|AMNH's rather weak representation of Stupendemys|
Huge fins on a large turtle give it carte blanche for international travel, something borne out by the sub-artic hopping leatherback turtles (dermochelys). The only other vertebrate that has a wider natural distribution are some species of whales.
Given what Wood has written about the humerus, one should think that these creatures were powerful swimmers, confirming what we already know about big humerus bones in turtles. The oversized humerus of the Galapagos Tortoise for example, bears the weight of the animal (up to 300 pounds) and extra weight is not a problem.
|Zoologist Gazillionaire Walter Rothschild|
Stupendemys existed at a time when proto-humans walked the earth, making them much more acceptable as a potentially surviving species, taking into account the order of Testudians' ability to have survived the Tertiary event that wiped out the dinosaurs, it should make them a top modern day candidate for large unidentified aquatic reptiles as described from Loch Ness, Lake Champlain and other large lakes. Add to that, turtle's present proven survivability, adaptability, diversity, potential extreme size and extreme range of distribution in the world.
|Snake Necked Pleurodira|
|Paleontologist Dr. Kenneth Carpenter proposes an adapted live birthing |
Plesioturtle as The Loch Ness Animal
|PLESIOTURTLE proposed for a KING KONG remake.|
c/o Mike Playfair
|The lone survivor of the Pensacola attack described a "turtle-like"|
monster and drew this picture
|Publicly unseen still from forensic investigator's files seems to show huge unknown |
turtle in Lake Champlain.
|Face compared to aquatic turtle|
|Illustration showing position of animal in upper photo|