Helicoprion
Over 150 years a Jurassic shark but now a dangerous Buzz saw ratfish, the Helicoprion in our "LOST DOLPHINARIUM"
About 290 million years ago the Buzz saw ratfish lived in the oceans off the southwestern coast of Gondwana, and later, Pangaea. It became extinct 250 million years ago.
Fossils of different species of Helicoprion(Click to view larger image).
Like some other species also the Helicoprion shark was described in 1899 only on the basis of some body parts, namely the spirally arranged clusters of the individuals' teeth, the so called "tooth whorl". Such a tooth cluster strongly remembers in the form of a circular saw and has 3 spirals with up to 180 teeth. Over the years more tooth whorl fragments were found and because of their differences new Helicoprion species were described.
Images in former time of Helicoprion(Click to view larger image).
Altogether eight different Helicoprion species are described. In average they are 3-4 m long, larger specimens up to 8m. Because of a tooth whorl which was discovered in 2011 and which measures 45 cm in diameter, it is estimated that this ratfish was about 10m long. In the meantime even a 60 cm large tooth whorl was found and would belong to a Buzz saw ratfish that possible exceeded 12 m in length. These large specimens are probably a new species too.
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For over a century scientists have tried to understand how the spiral tooth dentition does fit into the shark’s jaws and produced visions of sharks with tooth whorls hanging off their snouts, lower jaws, dorsal fins, caudal fins and even embedded deep in their throats. Even after the scientists generally agreed, that the teeth belonged at the tip of a long lower jaw, artists and scientists still developed different theories. Some speculated that the fearsome tooth whorl would hang out of the center of the lower jaw in an external coil, others have the tooth whorl in the center on the inside of the lower jaw or have it set back in the lower jaw looking like a buzz saw. Another idea was that a spiral dentition exists in both the upper and lower jaw.
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Size comparison of human and Helicoprion
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Spotted ratfish which is closely related to Helicoprion
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Only in 2013, a CT scan of a tooth whorl offered a perfect new vision about the Helicoprion. The tooth whorl totally filled the lower jaw. The jaw joint sat just right behind the weapon, and the spiral dentition was buttressed by jaw cartilage on either side. Besides, even stranger, Helicoprion didn’t have any upper teeth to speak of. The spiral of continually-added teeth was the creature’s entire dental armament. Further on, the skull cartilage of Helicoprion included a very specific double connection that is characteristic of a group of cartilaginous fish which are commonly known as ratfish and chimaeras. Since these scans we know now that Helicoprion don’t have an elongated jaw, and that it is really not a shark but a ratfish. Besides we understand also the function of its buzz saw teeth. Their analogy to a circular saw is almost perfect, not only that the tooth whorl is shaped like a saw, but when the jaw will be closed the teeth rotate backwards in a rotational saw motion. Such a strategy works well on squid and other soft-bodied cephalopods which are their main food.
Helicoprion enclosure in LOST ZOO
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We are really happy and proud that we could aquire this strange looking Buzz saw ratfish for our LOST ZOO. This rare and real exotic fish will be a great attraction in our LOST DOLPHINARIUM in a large tank just on the side of the Chinese Baiji to exhibit a rare freshwater species just on the side of a very rare and large seawater species.
Executive Curator
JURGEN LANGE
The various species of marine Buzz saw ratfish lived off the southwestern coast of Gondwana land. It first arose in the oceans 290 million years ago and eventually became extinct 250 million years ago. All the species of Buzz saw ratfish have a strange, but well working spirally arranged cluster of the individual’s teeth, the so called tooth-whorl, strongly reminiscent of a circular saw.
In the beginning scientists regarded the Helicoprion as a shark, but since a CT scanning in 2013 it is obvious now that indeed it is a rat fish and the chimaeras are the closest living relatives.
Body length: depending on the species in average 4-6 m, but some species also up to 10-12 m.
Diameter of tooth-whorl: 45-60 cm, 3 spirals with up to 180 teeth.
