00019 - Extremely Perfect 1.81 Inch Onchopristis Cretaceous Giant Sawfish Rostral Barb
00019 - Extremely Perfect 1.81 Inch Onchopristis Cretaceous Giant Sawfish Rostral Barb 00019 - Extremely Perfect 1.81 Inch Onchopristis Cretaceous Giant Sawfish Rostral Barb 00019 - Extremely Perfect 1.81 Inch Onchopristis Cretaceous Giant Sawfish Rostral Barb

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00019 - Extremely Perfect 1.81 Inch Onchopristis Cretaceous Giant Sawfish Rostral Barb

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Species
Onchopristis numidus, Hauq 1905
Age
Upper Cretaceous, Cenomanian stage, (~96 Million Years)
Location
Taouz, Kem Kem Basin, South Morocco
Formation
Tegana Formation, Red Sandstone Beds
Size
42 mm   •    in
Weight
6 g   •    oz
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Description
Spectacular rostral barb dentition of the extinct taxon of the giant sawfish, the Onchopristis numidus. This type of sawfish is a relatively common species in the cretaceous ecosystems in the north of Africa. It stands out in abundancy over many of the other types of fish which also shared the shame fluvial systems. Despite its relative abundance, the preservation of a sharp and defined tip is a very rare feature. Most teeth of this species, due to their length and stylized morphology, tend to lose the cusps during the sedimentarian transportation. Finally, during the fossilization, the lithostatic pressure also acts as a destructive agent for this delicate structures. 

This specimen is an example of an exceptional preservation state. It does not have any type of restoration. From root to tip, each detail reflects a startling variety of reddish and orangish hues.
The teeth with strong and vivid fossilization colors such as red, orange and black come from small paleochannels composed by thin layers, in the intermediate and upper stratigraphic levels (Red Sandstone Beds), from the Aoufous Formation (Kem Kem Basin, South of Morocco). The lithology of this body of sediment is characterized by the dominance of sandstones (also known as arenites) and fluvial gravel, of siliceous nature. Sometimes large concentrations of iron oxide are present, and then a small sample of that is usually present at the base of the tooth. These mineralizations are responsible for the wide range of beautiful reddish color tones, slowly drawn during millions of years via fossil-diagenetic processes. The complicated sedimentarian architecture of the layers where most large vertebrates are found makes the excavation methodology a real challenge. Sometimes the local miners have to excavate long tunnels that follow the distribution of the fossiliferous layer.

Onchopristis is a genus of extinct giant sawfish that lived in the Lower Cretaceous to Upper Cretaceous in North Africa and New Zealand. It had an elongated snout lined laterally with barbed teeth. It is a large sawfish, known from remains throughout North America, North Africa and New Zealand. It was very large, up to 8 m (26.2 ft) long when fully grown. As with modern sawfish, Onchopristis's eyes were on top of its head, to spot predators rather than prey, and its mouth and gills were under its body. The rostrum, or snout, was around 2.5 m (8.2 ft) long, lined with barbed teeth. In the type species, O. numidus, each tooth had one barb, but in O. dunklei there were two to five barbs on each tooth, two to three in O. d. praecursor, and three to five in O. d. dunklei. The rostrum most likely would have had electrosensors to detect food in the water below them like most modern sharks and some rays. Onchopristis may have raked through the riverbed to find and then eat prey. [This last paragraph is from Wikipedia - License: Attribution-ShareAlike 3.0 Unported]

This taxon was described by Hauq (1905) and belongs to the Pristidae family. Their fossils are a good indicator of paleoenvironments related with deltas and estuaries. This type of fish constituted a big part of the diet of the great ichthyophagous coetaneous dinosaurs, such as the Spinosaurus.
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