ONCHOPRISTIS NUMIDUS

ONCHOPRISTIS NUMIDUS ( SAWFISH ) ROSTRAL TOOTH

Tegana Formation - Kem Kem, Morocco

UPPER CRETACEOUS PERIOD:  97.5 - 91 million years ago

Edwardchristhoper.blogspot.com - These are one of the most fascinating fossil teeth available from a very bizarre creature that is not widely known, Onchopristis numidus.  Onchopristis numidus is an extinct large sawfish that lived during the days of the dinosaurs.  This particular Onchopristis numidus rostral tooth specimen is intact with NO REPAIR and NO RESTORATION.  Intact teeth of fine quality are very rare because these teeth are dug and often found in hard sediments.  They are almost always damaged during the extraction process.  Choice enamel, color and preservation.

Related to the modern day sawfish, the Onchopristis had a long, hard shovel-shaped snout lined on both sides with barbed teeth.  This fascinating member of the shark and ray family trolled the murky bottoms of warm Cretaceous seas nearly 100 million years ago.  To gain insight as to how this extinct animal might have lived we can examine the modern day sawfish.

Sawfishes are very lethargic animals, spending much of their day nestled in the muddy sea/river floor. At night, they scull slowly through the shallows, using their sensitive saw to find buried prey, which are then raked from the sediment to be consumed. It is useful to view the sawfishes' unique rostrum like a metal detector combined with a clam rake.

If small fishes, like mullet, swim past a hungry sawfish, this great ray will launch from the bottom, slashing its toothy weapon rapidly side to side. Gouged by the snout's awl-shaped teeth, injured fishes tumble to the sea floor, now immobilized and easy to catch!

Apart from its use in finding and disabling prey, the toothy rostrum is also a weapon of defense. When threatened, sawfishes will smack this jagged sword against attackers, whether they be sharks or fishermen. Generally, though, sawfishes are very gentle animals, preferring to lie quietly, undisturbed.

Very little is known about sawfish life history, but the late Dr. Thomas Thorson performed studies on a freshwater species, the Largetooth sawfish ( Pristis perotteti) from Lake Nicaragua. According to his findings, this sawfish lives approximately 25-30 years, attaining maturity in about 10 years. Females give live birth and pup sawfishes are around 2.5 ft long at birth, reaching a maximum length of 23 ft! A rubbery envelope surrounds the softened saw at birth to protect the mother from harm. It is thought that mating occurs every other year, with an average litter size of approximately 8 pups.

Sawfishes love muddy shallow water, and this is why many people are unaware of them. Few humans, apart from tribal villagers and fishermen venture into sawfish domain. These elasmobranchs possess a remarkable physiological system allowing them to travel from the sea into freshwater at will. Some species seem to spend most of their lives in rivers and lakes! It is likely that sawfishes require a variety of habitats and salinities to complete their lifecycle.

Roughly 40 species of modern sawfishes are known; only a handful survive today.

NICE ROBUST EXAMPLE!

1.5" long on the diagonal leading edge

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Source : http://www.paleodirect.com