Post by creature386 on Jul 8, 2013 1:38:15 GMT 5
Parotodus benedeni
Temporal range: Oligocene-Early Pliocene[1]
Location: USA, New Zealand, Australia, Japan[1]
Sciencifitic classification:
Chondrichthyes
Lamniformes
Otodontidae
Parotodus
P. benedeni[1]
Description:
Parotodus benedeni is a lamnoid shark known from large (~6 cm long[3]), robust teeth. The teeth are similar to those of mako sharks,[1] especially to those of the common, extinct mako species called Isurus hastalis, which had comparably sized teeth.[2] The crowns of the teeth are small and crown like. Upper anterior have broad crowns with a concave labial face, while lower anterior teeth have more narrow crowns, with a convex labial face. However, the lower anterior teeth have in exchange thicker and more massive crowns, than the upper anterior teeth. The posterior teeth don't show a significant variation, they all have large roots and low, very oblique crowns.[4] The root lobes of anterior teeth are circular in cross section.[3] Parotodus was a very rare shark, in the Lee Chreek Mine formation, 17,000 shark teeth are known, but only six belong to Parotodus.[4]
The ecology of this animal is poorly known, although we can suggest that the teeth had a different purpose than the one in modern sharks. They were rather comparable to the ones of mosasaurs and killer whales, that means a puncture and tear strategy, causing blatant wounds.[5]
Size:
There are different estimates for P. benedi, based on C. carcharias data. Using the enamel height, P. benedi's size can be estimated at 4.7 m. Using the measured upper tooth row length yields a total length of 6.5 m. Adding spaces between the tooth would increase the tooth row length by 17% (assuming a spacing comparable to the modern great white shark), yielding a total length of 7.6 m for the animal.[6]
Published weight estimates for the lower end range from 928 to 1,066 kg, and estimates for the higher end range from 4,118 to 4,822 kg.[6] Teeth from private collections indicate specimens 20% longer than the studied ones.[7]
During time, the teeth of P. benedeni got larger and more robust. The ones known from the Oligocene are quite small, but teeth from younger periods are larger and more robust. They likely did so, because marine mammals (which likely made up a great part of P. benedeni's diet) got larger and more diverse within the time.[5]
Phylogenetic position:
P. benedeni was a lamnoid, which was first referred to Isurus, because of superficial similarities, it however was later proposed to be an own Genus, because fine details separate these taxa. A detailed analysis has shown that P. benedeni was more a relative of Otododus and Carcharocles, than a relative of lamnidae members (like Isurus).[1]
The tree shows the position of Parotodus, and the family Otodontidae:[8]
Literature:
Bretton W. Kent, George W. Powell, Jr. Reconstructed dentition of the rare lamnoid shark Parotodus benedeni (le Hon) from the Yorktown Formation (Early Pliocene) at Lee Creek Mine, North Carolina In: The Mosasaur 6 p. 1-10
Bretton W. Kent: Speculations on the Size and Morphology of the Extinct Lamnoid Shark, Parotodus bend (le Hon). In: The Mosasaur. 6, 1999, p. 11-15
Footnotes:
[1] Kent and Powell 1999 p. 1
[2] Kent and Powell 1999 p. 3
[3] Kent and Powell 1999 p. 4
[4] Kent and Powell 1999 p. 2
[5] Kent and Powell 1999 p. 7
[6] Kent 1999 p. 12
[7] Kent 1999 p. 14
[8] Kent 1999 p. 11
Temporal range: Oligocene-Early Pliocene[1]
Location: USA, New Zealand, Australia, Japan[1]
Sciencifitic classification:
Chondrichthyes
Lamniformes
Otodontidae
Parotodus
P. benedeni[1]
Description:
Parotodus benedeni is a lamnoid shark known from large (~6 cm long[3]), robust teeth. The teeth are similar to those of mako sharks,[1] especially to those of the common, extinct mako species called Isurus hastalis, which had comparably sized teeth.[2] The crowns of the teeth are small and crown like. Upper anterior have broad crowns with a concave labial face, while lower anterior teeth have more narrow crowns, with a convex labial face. However, the lower anterior teeth have in exchange thicker and more massive crowns, than the upper anterior teeth. The posterior teeth don't show a significant variation, they all have large roots and low, very oblique crowns.[4] The root lobes of anterior teeth are circular in cross section.[3] Parotodus was a very rare shark, in the Lee Chreek Mine formation, 17,000 shark teeth are known, but only six belong to Parotodus.[4]
The ecology of this animal is poorly known, although we can suggest that the teeth had a different purpose than the one in modern sharks. They were rather comparable to the ones of mosasaurs and killer whales, that means a puncture and tear strategy, causing blatant wounds.[5]
Size:
There are different estimates for P. benedi, based on C. carcharias data. Using the enamel height, P. benedi's size can be estimated at 4.7 m. Using the measured upper tooth row length yields a total length of 6.5 m. Adding spaces between the tooth would increase the tooth row length by 17% (assuming a spacing comparable to the modern great white shark), yielding a total length of 7.6 m for the animal.[6]
Published weight estimates for the lower end range from 928 to 1,066 kg, and estimates for the higher end range from 4,118 to 4,822 kg.[6] Teeth from private collections indicate specimens 20% longer than the studied ones.[7]
During time, the teeth of P. benedeni got larger and more robust. The ones known from the Oligocene are quite small, but teeth from younger periods are larger and more robust. They likely did so, because marine mammals (which likely made up a great part of P. benedeni's diet) got larger and more diverse within the time.[5]
Phylogenetic position:
P. benedeni was a lamnoid, which was first referred to Isurus, because of superficial similarities, it however was later proposed to be an own Genus, because fine details separate these taxa. A detailed analysis has shown that P. benedeni was more a relative of Otododus and Carcharocles, than a relative of lamnidae members (like Isurus).[1]
The tree shows the position of Parotodus, and the family Otodontidae:[8]
Literature:
Bretton W. Kent, George W. Powell, Jr. Reconstructed dentition of the rare lamnoid shark Parotodus benedeni (le Hon) from the Yorktown Formation (Early Pliocene) at Lee Creek Mine, North Carolina In: The Mosasaur 6 p. 1-10
Bretton W. Kent: Speculations on the Size and Morphology of the Extinct Lamnoid Shark, Parotodus bend (le Hon). In: The Mosasaur. 6, 1999, p. 11-15
Footnotes:
[1] Kent and Powell 1999 p. 1
[2] Kent and Powell 1999 p. 3
[3] Kent and Powell 1999 p. 4
[4] Kent and Powell 1999 p. 2
[5] Kent and Powell 1999 p. 7
[6] Kent 1999 p. 12
[7] Kent 1999 p. 14
[8] Kent 1999 p. 11
