REPERTI DI SQUALI RARI ORIGINALI DI RICCARDO

quelli col segno "+" sono in esposizione alla "Shark Expo"

RAR

SQUALO RARO

MISURE

PROVENIENZA

1* Cladoselache - -
2* Petalodus carbon 330 ma. - -
3+ Edestus - -
4+ Helicoprion -
5 Stetachantus - -
6* Xenacanthus devon 300 ma. 4 x 2 mm -
7* Orthacanthus 260 ma. 10 x 4 mm -
8* Pleuracanthus texensis (xenacanth.) permiano 250 ma. 15 mm -
3) The spectacular Scissor-Tooth Shark (Edestus giganteus), of the late Carboniferous, sported some of the weirdest dentition ever evolved. Like modern sharks, Edestus continually grew replacement teeth inside the jaws, but unlike them retained old, worn teeth until they protruded far in front of the fish’s head (thus the youngest teeth are at the rear of the jaws, while the oldest are at the tips). It is not known how Edestus actually used its pinking-shear jaws, but - as it grew to about the same length as the modern White Shark - it must have been a formidable predator indeed.

4) Helicoprion lived about 250 million years ago. It belongs to a group of early sharks whose jaws evolved an elaborate buzz saw-like tooth whorl composed of successively larger replacement teeth, each one fixed to the tooth in front, forming an ever-growing spiral with the earliest (smallest) teeth at its center. This structure may have been used to injure or disable prey, which the shark could then eat at leisure. Helicoprion may have reached lengths over 10 feet, but many of its relatives were smaller and had less impressive tooth spirals.

6) XENACANTHUS TOOTH - Wellington Formation - Jefferson Co, Oklahoma, U.S. PERMIAN PERIOD:  260 million years ago. The now extinct Xenacanthus was a highly specialized freshwater shark that existed from the Devonian Period 345 million years ago to the Permian Period.  A long spine grew from the back of the head followed by a long and continuous ribbon-like dorsal fin that gave it the appearance of an eel.  The double forked teeth were another unique characteristic most likely used to feed on small crustaceans and bony fish. A full grown Xenacanthus attained lengths of 3 feet.

7) ORTHACANTHUS TOOTH - Wellington Formation - Jefferson Co, Oklahoma, U.S.PERMIAN PERIOD:  260 million years ago. From a period in time before the dinosaurs even walked the earth, the bizarre Orthacanthus thrived in prehistoric swamps and bayous in Europe and North America. The Orthacanthus was an ancient freshwater shark that is no longer in existence. It had a very long spine protruding from the back of the head followed by a long ribbon-like dorsal fin that gave it the appearance of an eel.  The double forked teeth were another unique characteristic.  A full grown Orthacanthus is believed to have grown to 10 feet in length.