Helicoprion sp.

[Atolm]

... Okay, here's a pic of an extinct shark from before the dinosaurs aproximately 250 million years ago in the mid-Permian...all that is 100% known of this beast are the teeth. These teeth seemingly show that as the shark got older or the teeth began to wear down that instead of sheading them as in modern sharks, they are stored and begin to curve into a circular saw like structure...hence giving the shark its name Helicoprion which in-turn means whorl or spiral blade.
only 5% of this rendition of this shark is accurate, the rest is total speculation based on other close relative edestoid sharks, possible lifestyle, and modern shark physiology...

Special thanks to WZ for hosting the pic.

Enjoy:

[Reverend]

WHOA thats totally amazing! What would this things size be around?

[Atolm]

reverend said:

WHOA thats totally amazing! What would this things size be around?

Thanks mate
The size of Helicoprion is currently held at 10-20 feet at best...but there is a tread of thought that these bad-boys might have gotten much, much larger... though, the actual reality is we just donot know for sure. See the problem is shark, chimera and ray skeletons are composed of cartilage (the same suff that creates the structure of your nose and ears), and have no bones...and since cartilage decomposes at a much faster rate than bone, the the already rare chances of fossilization, become an extremely rare case for them...the teeth of sharks and their kin are composed of dentine (not the gum) and covered with an enamel...thats why their teeth fossilize, while their skeletons donot.
To be on the coservative side I would stay with the current thinking...but you never know...an 80-100ft Edestoid shark like Helicoprion could have existed, but with more eel-like proportions similar to those found in the living dogfish and 6-7 gilled shark families, rather than the more fimilar shape I had attributed to the pic.
Bottom line is, we just need the evidence to present itself

[Centurus]

Everyday they're finding more and more species alive that were thought to be extinct. I wouldn't be surprised if this particular species managed to survive all this time and still lives in remote areas of the sea, waiting to be discovered.

[Atolm]

that would be most unlikely...as the organisms that you are refering to are all modern relatives of the extinct forms.

[Centurus]

No, not really. Back in the 60s or so, scientists discovered living members of a species of fish that they had believed gone extinct roughly 100 million years ago or so. I believe they found it off the coast of Africa. Can't remember exactly where, or what the species was called, but, they were surprised to find even one still alive today, pretty much exactly the same as it had lived all those millions of years ago.

Now, last I checked, there are several hundred thousand known living specimens in the sea today.

This world, as crowded with human beings as it is now, is still large, vast, and holds many secrets. All I am saying that it may be possible that this species of shark could still exist today, albeit in smaller numbers and more remote areas than when they thrived in the oceans.

[Atolm]

f9thdaihak said:

No, not really. Back in the 60s or so, scientists discovered living members of a species of fish that they had believed gone extinct roughly 100 million years ago or so. I believe they found it off the coast of Africa. Can't remember exactly where, or what the species was called, but, they were surprised to find even one still alive today, pretty much exactly the same as it had lived all those millions of years ago.

Now, last I checked, there are several hundred thousand known living specimens in the sea today.

This world, as crowded with human beings as it is now, is still large, vast, and holds many secrets. All I am saying that it may be possible that this species of shark could still exist today, albeit in smaller numbers and more remote areas than when they thrived in the oceans.

you are referring to the coelacanth...which is a fish that the family to which it belongs to was thought to be extinct...but the coelacanth is not its prehistoric ancestors...it is its modern relative...much in the same way that the mako shark is the living relative of the extinct Squalicorax pristodontus or even the much more recently extinct Isurus hastalis.
They are not the same fish, but share a family connection...same goes with African lungfish, Crocodiles, goblin sharks, and other species.

[Reverend]

So no Megs still around right? I have reccurring nightmare of diving in deep ocean and looking down to see 70ft of death coming up at me... lol

[Atolm]

lol... aye for all intents and purposes, no Megs...but there are a lot of "fisherman stories" of seeing them

[Reverend]

sweet now only just have giant squids to worry about, should I ever deep sea swim, which, hope I don't I am a true Capricorn, earth-bound... boat are great and watr is great, just not too much.. heh..
anyway, if you have any oher interpretations do share them please

[Atolm]

will do

[Atolm]

Ok mates, here's Edestus giganteus...Again, almost nothing is known about this shark, except its jaws and teeth which in Edestus' case are arranged in scissor-like fashion were both the top and lower parts of the jaws contain just one row of teeth arranged in single file creating the afore mentioned scissor-esque oral condition...it should be noted that like the shark above Helicoprion, Edestus most likely did not shed its teeth, but rather the jaws continued growing...this leaves to the possiblity that the jaws of Edestus could possibly grow so long that it would have a profile very much like a swordfish but with two "swords" rather than one on the billfish, just some food for thought. Also, like it's relative Helicoprion, Edestus was a very large shark some 20+ feet long, with the speculation that the fish could have grown extremely large.
Both Edestus, and Helicoprion are in the same family of sharks the EUGENEODONTIDA.
Enjoy:


As always, special thanx to WZ for host'n my stuff

[stardragon]

I don't know about "smiling" , but this guy's definitely doing a jig like a porpoise! ;D

I remember I saw a Megoladon not 3 months ago on the Sci-Fi channel...(oh wait.. nm).

[Atolm]

Here is a more Chimeariod rendition of Helicoprion (sorry about the split, the original is rather large for the scanner :/ )

[Atolm]

[vipergb34]

Its a good thing there extinct.

[Atolm]

vipergb34 said:

Its a good thing there extinct.

yeap...though I'd sure love to really see one

Here's another extinct shark call Hybodus...
Hybodont sharks first evolved in the early to mid Jurassic(though they may actually be older than that)and lasted to the late Cretaceous...they died off 65 million years ago.

[Atolm]

Here are 2 more possible life restorations of Edestus giganteus



And here is Falcatus. a stethacanthid-type of shark. Only the Males have that modified protuberance of a first dorsal fin. Unlike Edestus or Helicoprion, Falcatus, like Hybodus(the blue shark in the above post with the horns), we do know how they look like(both males and females).
Enjoy:

[Atolm]

2 more for (possible)Edestus