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Sacaco dentition

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Gordon and glenn and sacaco dentition

Gordon Hubbell (left) and Glenn Reed (right) with the Sacaco dentition. Photo credit: [www.tellmewhereonearth.com] (Sharks, page 14).

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Overview of the dentition. Photo credit: [www.tellmewhereonearth.com] (Sharks, page 14).

"It's the only fossilized partial skull of a white shark that's ever been found,"
-----Gordon Hubbell, the fossil's owner.

The Sacaco dentition refers to a roughly 5 million year old articulated shark dentition identified as C. carcharias from the upper Pisco Formation of Sacaco, Peru, on February of 1988 by fossil enthusiast Gordon Hubbell. Hubbell purchased the fossil from a farmer during his first trip to Peru, which coincidentally occurred only a few days after the discovery. The Pisco Formation, famous for its rich fossil beds dating from the Late Miocene to Pleistocene, is about 1 million to 9 million years ago. The region was once a sheltered, shallow marine environment ideal for preserving skeletons. The formation has produced articulated broad-toothed mako shark skeletons as well as fossils of whales, aquatic sloths and sea turtles. The total length of the specimen is estimated at 6 meters long. It is the only complete fossilized skull of a Great White shark that has ever been recovered.

DentitionEdit

The dentition includes parts of the spinal column, the head skeleton, and 222 teeth.[1][2]

The upper A3 teeth are distally directed.[2] This specimen presented two possibilities, neither of which supported the arguments of the "Carcharodon" megalodon advocates. If it was Carcharodon carcharias, then the direction of the Upper A3 is not important. If it's not, then it was from the species referred to as Isurus hastalis or escheri — with teeth that are otherwise indistinguishable from C. carcharias — serrations and all. If this were the case, they should properly be referred to as Carcharodon hastalis and/or C. escheri. The list of possible genera expanded in 1999 when talk surfaced of the resurrection of Glikman's Cosmopolitodus for the "broad-toothed" makos.

Photographic conditions were not the best, being in a deep glass case in a poorly lit room. However, the below photo's provide some detail of this great specimen.

The Dentition

Recent eventsEdit

Fossilshark03

Dana Ehret seen here with the Sacaco dentition in the study at Gordon Hubbell's private gallery in Gainesville, Fla., on March 6, 2009.

Pisco sacao dent.1

Dr. Bruce MacFadden (left) and Dr. Tom DeVries (right) relocate the original collection site of the dentition and reenact the original collecting photograph.

Pisco sacaco dent.2

Dana Ehret samples the vertebrae of the fossil using a MicroMill(TM), an automated drilling device connected to a computer.

"The completeness of this specimen allows us to take a closer look at the interrelationships between white and mako sharks"
-----Dana Ehret

In the March 2009 issue of the Journal of Vertebrate Paleontology, Dana Ehret, a Florida Museum of Natural History researcher, and his colleagues further determined that the prehistoric shark was 20 years old when it died by counting light and dark bands in the shark's vertebrae, which calcify with age.[3] Such bands have been shown to represent seasonal changes in modern sharks; this was tested in the fossil by examining difference in the isotopic composition of the dark and light bands, which reflects seasonal temperature changes. A modern great white shark of similar age likely would have been larger, suggesting that this fossil species grew at a slower rate.

Shimada, an associate professor at DePaul University and a research associate in paleontology at the Sternberg Museum of Natural History, believes the genus Carcharocles belongs to the now-extinct family Otodontidae.

The Sacaco dentition has been the subject of much heated debate regarding whether or not the megalodon species belongs in the genus Carcharodon, or Carcharocles.


ReferencesEdit

  1. ^ "Ancestor of “Jaws”: 4-million-year-old shark fossil from Peru provides new evidence on the origins of the great white shark". SVP. SVP. March 11, 2009. http://www.vertpaleo.org/news/permalinks/2009/03/11/PRESS-RELEASE---Ancestor-of-Jaws-4-million-year-old-shark-fossil-from-Peru-provides-new-evidence-on-the-origins-of-the-great-white-shark/. Retrieved on 2009-04-15. 
  2. ^ a b Dana J. Ehret, Gordon Hubbell, and Bruce J. Macfadden, Journal of Vertebrate Paleontology, 2009, 29(1):1–13
  3. ^ Ehret, D. J., G. Hubbell, and B. J. MacFadden. 2009. Exceptional preservation of the white shark Carcharodon (Lamniformes, Lamnidae) from the Early Pliocene of Peru. Journal of Vertebrate Paleontology, volume 29, No. 1.[Feature Article]

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