| 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.
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