Helicoprion
Encyclopedia
Helicoprion was a long-lived genus
of shark
-like cartilaginous fish that first arose in the oceans of the late Carboniferous
, survived the Permian-Triassic
Extinction
Event
, and eventually went extinct during the early Triassic
some .
The only fossils known are the teeth, which were arranged in a fantastic "tooth-whorl" strongly reminiscent of a circular saw
. It was not until the discovery of the skull of a relative, Ornithoprion, that it was realized that the tooth-whorl was in the lower jaw. The tooth-whorl represented all of the teeth produced by that individual in the lower jaw, in that as the individual grew, with the older, smaller teeth being moved into the center of the whorl by the appearance of larger, newer teeth. Comparisons with other eugenodontids suggest that Helicoprion may have grown up to 10-15 ft
long.
The exact location of the tooth-whorl in the lower jaw is unknown. Most current reconstructions place the whorl in the front of the lower jaw; however this would create drag, making the shark a less efficient swimmer, and turbulence, alerting prey of its approach. An alternate reconstruction, created by Mary Parrish under the direction of Robert Purdy, Victor Springer and Matt Carrano for the Smithsonian
, places the whorl deeper into the throat. This arrangement would be best suited for soft bodied prey.
-paleozoologicalmuseumofchina-may23-08.jpg)
The individual teeth are serrated, and it is implied that Helicoprion was carnivorous. As there has yet to be an actual skull found, exactly how it captured or fed on its prey is the subject of a great deal of speculation. One hypothesis that it preyed on ammonite
s and that the teeth were specialized for the job of breaking into the ammonites' shells. Another idea was that the shark would swim into a school of fish and fling out the jaw, snagging prey on its many teeth. Notable specimens of Helicoprion have been found in eastern Idaho, northern Utah, and the far central western part of Wyoming.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....
-like cartilaginous fish that first arose in the oceans of the late Carboniferous
Carboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...
, survived the Permian-Triassic
Permian-Triassic extinction event
The Permian–Triassic extinction event, informally known as the Great Dying, was an extinction event that occurred 252.28 Ma ago, forming the boundary between the Permian and Triassic geologic periods, as well as the Paleozoic and Mesozoic eras...
Extinction
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
Event
Extinction event
An extinction event is a sharp decrease in the diversity and abundance of macroscopic life. They occur when the rate of extinction increases with respect to the rate of speciation...
, and eventually went extinct during the early Triassic
Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...
some .
Circular saw
The circular saw is a machine using a toothed metal cutting disc or blade. The term is also loosely used for the blade itself. The blade is a tool for cutting wood or other materials and may be hand-held or table-mounted. It can also be used to make narrow slots...
. It was not until the discovery of the skull of a relative, Ornithoprion, that it was realized that the tooth-whorl was in the lower jaw. The tooth-whorl represented all of the teeth produced by that individual in the lower jaw, in that as the individual grew, with the older, smaller teeth being moved into the center of the whorl by the appearance of larger, newer teeth. Comparisons with other eugenodontids suggest that Helicoprion may have grown up to 10-15 ft
1 E1 m
To help compare different orders of magnitude this page lists lengths between 10 metres and 100 metres.Distances shorter than 10 metres-Conversions:10 metres is equal to:* 10 metres...
long.
The exact location of the tooth-whorl in the lower jaw is unknown. Most current reconstructions place the whorl in the front of the lower jaw; however this would create drag, making the shark a less efficient swimmer, and turbulence, alerting prey of its approach. An alternate reconstruction, created by Mary Parrish under the direction of Robert Purdy, Victor Springer and Matt Carrano for the Smithsonian
Smithsonian Institution
The Smithsonian Institution is an educational and research institute and associated museum complex, administered and funded by the government of the United States and by funds from its endowment, contributions, and profits from its retail operations, concessions, licensing activities, and magazines...
, places the whorl deeper into the throat. This arrangement would be best suited for soft bodied prey.
Ammonite
Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct subclass within the Molluscan class Cephalopoda which are more closely related to living coleoids Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct...
s and that the teeth were specialized for the job of breaking into the ammonites' shells. Another idea was that the shark would swim into a school of fish and fling out the jaw, snagging prey on its many teeth. Notable specimens of Helicoprion have been found in eastern Idaho, northern Utah, and the far central western part of Wyoming.