Carcharodon Megalodon (Mega Shark)

[DAVIDE]

Large fossilized Megalodon teeth are among the most startling of natural objects. They are huge blackish triangles that appear 'puffed up', resembling fresh-baked (fresh-burned?) cookies. The root is bilobed and rough, in stark contrast to the smooth, enamel-like polish of the blade. The blade itself is often cracked longitudinally and the edge has about 50 serrations per inch (20 per centimetre). The heft of a good-sized specimen is remarkable - about three-quarters of a pound (0.4 kilograms). It is hard to think of these massive stones as ever having been teeth. But that's exactly what they were. This undeniable fact has generated much awestruck speculation about what the entire shark must have looked like.
Fossilized teeth are almost all that remains of Megalodon. Therefore, placing some of these teeth in a model of the long-gone cartilaginous jaws is an expedient way to start reconstructing this creature. But how many teeth and how big to make the jaws? Since Megalodon teeth so closely resemble those of the modern white shark in form but are about three times as large, it seemed to early museum curators that a scaled-up model of White Shark jaws would be a reasonable approximation. Despite their huge size, these early reconstructions were not as scary-looking as one might imagine: resembling gigantic, white lips filled with hundreds of blackish fossil teeth. (Fossil shark teeth can be almost any color - black, purple, blue, green, brown, red, pink, orange, yellow, beige, or almost white - depending upon the precise chemistry of the sediment in which they were deposited. Because most commercially-sold megalodon teeth come from Cooper River and other South Carolina deposits rich in dark phosphates, these fossils are almost always dark grey, brown, or black.) But the stand-in jaws did give an impression of the sheer enormity of megalodon. Measuring eleven feet (3.4 metres) tall and nine feet (2.75 metres) across, the reconstructed megalodon jaws suggested a monster shark more than 80 feet (25 metres) in length. Small wonder that, even today, plaster reconstructions of Megalodon jaws are among the most popular paleontological exhibits in museums.

Reconstruction of the jaws and skull of Megalodon, left,
based on an extrapolation from the White Shark, right.
Re-drawn from Gottfried, Compagno, and Bowman 1996
(pp 55-66 In Klimley and Ainley [eds.] Great White Sharks:
the Biology of Carcharodon carcharias [Academic Press, San Diego])

How Big was Megalodon?

Comparing the largest known White Shark teeth with those of Megalodon seems a natural way to figure out how large the fossil species was. Ichthyologist John E. Randall was the first to point out that in the White Shark, the largest upper teeth (second anteriors) are about as tall as the jaw that contains them is high. The early Megalodon reconstructions, however, featured jaws about three times too high in proportion to the teeth. Randall also suggested that there is a more-or-less direct linear correlation between a White Shark's tooth enamel height and its total length. When Randall plotted a graph of tooth enamel height for white sharks of known length and the enamel height for the largest-known megalodon teeth, the position of the latter correlated to a total length of about 43 feet (13 metres). How could the museum curators have been so far off in their estimated size of Megalodon? Apparently, the original reconstructions relied on fossil teeth collected from several sites (thus representing several individuals), but they were all about the same size. However, in all extant lamnoids - including the White Shark - posterior teeth (those toward the corners of the jaws) are much smaller than anterior teeth (near the symphysis, or center, of the jaws). As a result of Randall's work, early reconstructions of Megalodon are now known to be at least a third too large.
In 1992, paleontologist John Maisey oversaw the construction of a model set of Megalodon jaws for the Smithsonian Institution. The reconstruction was inspired by the fortuitous discovery of a relatively complete set of fossil Megalodon teeth found in a North Carolina quarry by amateur fossil collector Peter Harmatuk. Starting with these fossilized teeth, Maisey based his interpretation of the jaws that had once contained them on both Randall's estimate of Megalodon's size and his own extensive studies of shark teeth and jaw suspension. Maisey's model Megalodon jaws are about six feet (1.8 metres) across - corresponding to a 40-foot (12-metre) shark - and include more accurate muscle attachment sites, making them look decidedly less lip-like than earlier reconstructions. Maisey's version thus provides us with a smaller (though still awesome) - but more accurate - impression of the Incredible Shrinking Megalodon.
But few things die more reluctantly than a Really Big Fish story. A 1996 paper by paleontologist Michael Gottfried, shark systematist Leonard Compagno, and S. Curtis Bowman of the Hughes-Bowman Design Group casts some doubt on Randall's method for estimating the size of Megalodon. According to Gottfried and his co-workers, White Shark tooth enamel height does not necessarily increase in proportion with the animal's total length. In white sharks longer than about 16 feet (5 metres), tooth size seems to level off at a maximum size independent of further increase in body length. To remedy these shortcomings, Gottfried et al. used new data and several techniques to better estimate the size and weight of megalodon. They came up with a maximum total length of about 52 feet (15.9 metres) and an approximate mass of 48 tons (tonnes). By comparison, the largest known White Shark was about 23.5 feet (7.1 metres) long and had a mass of roughly 2.3 tons (tonnes).

Reconstruction of the skeleton of Megalodon,
based on an extrapolation from the White Shark.
Re-drawn from Gottfried, Compagno, and Bowman 1996
(pp 55-66 In Klimley and Ainley [eds.] Great White Sharks:
the Biology of Carcharodon carcharias (Academic Press, San Diego)

In the Flesh

A creature over twice the length of the largest known Great White with teeth more than three times as large suggests a 'monster' shark with disproportionately huge jaws and a stout, over-sized head. Gottfried, Compagno, and Bowman also attempted to reconstruct what Megalodon might have looked like in life. Since the only fossil material definitely assignable to megalodon is a few dozen vertebral centra and several hundred teeth, the authors had to rely heavily on extrapolations from the modern White Shark, which they believe to be its closest living relative. Leonard Compagno has made extensive studies of the jaws, teeth, gill arches, crania, muscles, et cetera, of most species of extant shark, including recent work on the skeletal anatomy of the white shark. Guided by Compagno's formidable expertise, Gottfried and his co-workers reconstructed Megalodon as having a broader and more domed cranium than the White Shark, with a shorter snout, less elevated eye sockets, and with its very robust teeth set in more massive jaws. They also suggested that Megalodon had a greater number of vertebrae and proportionately larger pectoral fins than the White Shark. If this latest reconstruction is accurate, Megalodon was probably stouter than a scaled-up White Shark would be, with a blunter and wider head and bigger pectoral fins to support all that extra mass up front - sort of a great white on steroids.



http://www.elasmo-research.org/educa..._megalodon.htm

Spoiler Alert, click show to read: 

[Markas]

Forget about it John Hammond, no way we're having these brought back. Where's the link to the petition?

[DAVIDE]

[Phier]

I thought that it was determined the Megalodon was related to the Mako and not the white shark.

[DAVIDE]

Initially i thought the same..


Does Megalodon Still Live?


We will probably never know for sure why Megalodon became extinct. But we can probably be grateful that it did: a 52-foot (16-metre) version of the White Shark with jaws large enough to engulf a rhino would almost certainly make recreational swimming or pleasure boating a LOT less enjoyable. A number of scientifically untenable - but enormously entertaining - novels have been published, exploring just this possibility. The giant Mega-Tooth Shark (Carcharocles megalodon) is reconstructed here as a scaled-up White Shark (Carcharodon carcharias) and in 'hot pursuit' of Allodesmus, an early sea lion-like pinniped. Recent evidence strongly suggests that megalodon is not closely related to the modern White Shark and it is my suspicion that it probably didn't look much like it, either. But, barring an actual fresh specimen turning up, we'll never know for sure.
Megalodon is the toothy stuff of which legends are made. There are those who want desperately to believe that somewhere, perhaps in the deep ocean, Megalodon still lives. There is absolutely no scientific evidence to support such beliefs. But this hasn't stopped a small yet vociferous group of True Believers from conjuring up their own evidence. Unfortunately for them, most of this 'evidence' doesn't hold scientific water:

Megalodon Lives!

The Coelacanth (Latimeria chalumnae) was thought to be extinct for more than 60 million years until a live specimen was captured in 1938. We now know that there is a small but definitely surviving population of these ancient fish in very deep waters off eastern Africa and another was recently discovered off Indonesia. Who's to say that Megalodon does not also survive?

Less than 5% of the deep-sea has been explored, and even less than that sampled biologically. Yet we know that sharks live at least as deep as 12,000 feet (3,660 metres) and Sperm Whales (Physeter macrocephalus) are believed to dive to 10,000 feet (3,050 metres) in search of squid. If there's enough food down there for 60-foot (18-metre) whales, there is probably enough to support Megalodon

Based on the average rate of deposition of manganese dioxide around nuclei composed of fossil shark teeth, some have calculated that Megalodon may have lived as recently as 11,000 years ago, rather than died out 1.6 million years ago, as suggested by radiometric dating. In geological terms, that's yesterday.

New and unprecedented marine creatures are still being discovered, some of them quite large - like the 15-foot (4.5-metre) Megamouth Shark (Megachasma pelagios) discovered in November 1976.

There have been numerous, consistent reports by credible witnesses of gigantic sharks - like the 100+-foot (30+-metre) ghostly whitish shark reported from Broughton Island, Australia, in 1918, which was seen by several experienced commercial crayfishermen.

Megalodon is Gone

It is true that coelacanths were believed to have died out long ago, but just because one species thought to be extinct turned up alive and well doesn't necessarily mean that Megalodon survives too.

Although very little abyssal life has been sampled, the deep-sea is a very difficult environment demanding numerous significant specializations. Amount of food in the deep-sea is not the issue. Megalodon seems to have been limited to warm, shallow seas near coastlines and there is no evidence it had any specializations that would have enabled it to survive the intense cold of the deep-sea.

True, but new evidence suggests that the rate of manganese dioxide deposition is highly variable, dependent upon (among other factors) regional and seasonal fluctuations in primary productivity by phytoplankton. Besides, even 11,000 years is almost certainly far longer than the generation time of Megalodon. Extinct is extinct, no matter how recent in geological terms.

The discovery of new species - even large and spectacular ones like Megachasma - does not, of itself, imply that a particular species, Megalodon, will necessarily be re-discovered

Eye witness accounts are notoriously unreliable and anecdotal evidence impossible to verify. The sea and atmosphere can play tricks on even the most experienced mariner. Multiple sightings of a well-publicized archetype - such as UFO's, Elvis, ape-men, sea serpents, or giant sharks - in no way verify that those reporting them witnessed a 'real' phenomenon, only that they could not identify what they saw as something prosaic and the closest identity that fits their recollections (often formed on the briefest of glimpses) happens to conform with one of these archetypes, which act as convenient templates for the indescribable.

Lost fishing gear does not necessarily mean that Megalodon is the cause. Fishing gear gets lost for all kinds of prosaic reasons: fouled in boat props, hung up on rocks, coral, or bottom clutter, human error or carelessness. In addition, this 'argument' presupposes that Megalodon exists at all. One cannot catch what is not there to be caught.

Of course, absence of evidence is not evidence of absence. But none of the foregoing 'arguments' changes the fact that no fresh Megalodon tooth has ever been collected. If Megalodon still exists, there can't be just one of them. A whole population of Megalodon would shed tens or hundreds of thousands of teeth every year. So, until someone produces a recently shed tooth - or better yet, a fresh carcass - it is probably best to consider Megalodon extinct.
There are those who would regard the extinction of Megalodon as a tragic loss, that our planet is somehow less wonderful for this great shark's passing. But I am not among them. If the history of life on Earth has taught us anything, it is that – fundamentally – species continually come and go. The sharks we have today – from the wonderfully bizarre hammerheads (family Sphyrnidae) and tiny, glow-in-the-dark lanternsharks (family Etmopteridae) to the gigantic, plankton-grazing Whale Shark (Rhincodon typus) to the awesome splendor of the mighty Great White (Carcharodon carcharias) – are plenty spectacular enough for me.
Fantasies can be harmless and a lot of fun, but those of us who can appreciate things as they really are can count ourselves among the very luckiest of people.




Source: the same website

[MathiasOfAthens]

Whos to say that the lockness, which is really a dino fish doesnt still exist in the ocean. Dont ask me why it is in the Lockness (maybe underwater tunnel). Anyway, the megadon serves no purpose and if still allive should be exterminated immediately to protect surfers and divers.

[DAVIDE]

Whos to say that the lockness, which is really a dino fish doesnt still exist in the ocean. Dont ask me why it is in the Lockness (maybe underwater tunnel). Anyway, the megadon serves no purpose and if still allive should be exterminated immediately to protect surfers and divers.

how do u think to catch a 18 metres long shark? it's impossible just to get close to it.. he couldd eat your boat directly with a single bite

[Markas]

Whos to say that the lockness, which is really a dino fish doesnt still exist in the ocean. Dont ask me why it is in the Lockness (maybe underwater tunnel). Anyway, the megadon serves no purpose and if still allive should be exterminated immediately to protect surfers and divers.

The Loch Ness monster exists?