Great Whites 'not Evolved From Megashark'

[Auspex]

A new fossil discovery has helped quell 150 years of debate over the origin of great white sharks.

LINK

[THobern]

That specimen was found ages ago, and barely anyone at this point thinks that the great white is a direct descendant of the megalodon. The only contemporary paper that takes that view was from that bunch in Otago; we're looking at you, Bobby.

[redleaf101]

hehe =P

[THobern]

Though, that's not to say that they're not adding anything.

[Angus Stydens]

Wow, check out this article and the photo that accompanies it!

http://www.bbc.co.uk/news/science-environment-20318175

Angus Stydens

[Angus Stydens]

Here is a link to an abstract about the discovery of the shark:

http://www.bioone.org/doi/abs/10.1671/039.029.0113?journalCode=vrpa&

[Boesse]

Some other highlights of the paper: Cosmopolitodus/Isurus hastalis is reclassified as a species of Carcharodon, and the "transitional" species is now Carcharodon hubbelli.

I'm good friends with Mike Gottfried - he visited here in May to work on a Cretaceous tarpon fossil; it was good fun. I got the impression that he's rather sick of the whole debate, and prefers to discuss other subjects he finds more interesting. Any way, he's a very friendly, approachable guy. We agree to disagree, and leave it at that.

[Paleoc]

Proponents of megalodon ---> Carcharodon point at the 3rd upper anterior (sometimes referred to as an intermediate) tooth inclined mesially (i.e,, reversed) as the key evidence. The reasoning is that in Isurus, it is inclined distally. This specimen shows a mesially inclined 3rd upper anterior. What is continuously overlooked is that on rare occasion, modern Carcharodon jaws will have that tooth distally inclined as well.

Here is a juvenile dentition image which has been artificially flattened (image processing). Note the angle of the 3rd upper tooth.

And a large adult jaw I found for sale on the internet several years ago. Again note the angle of the 3rd upper tooth.

Edited November 27, 2012 by Paleoc

[siteseer]

Yeah, photos of the specimen have circulated for years because Gordon had it in his museum. I saw it in person for the first time about eight years ago. I heard about the paper a couple of weeks ago but haven't copied it yet.

That specimen was found ages ago, and barely anyone at this point thinks that the great white is a direct descendant of the megalodon. The only contemporary paper that takes that view was from that bunch in Otago; we're looking at you, Bobby.

[siteseer]

Bobby,

Yeah, that name change is going to irritate some collectors and researchers, but for years, that looked like the direction it was going due to name priority (see page 34 in Mark Renz' book, "Megalodon: Hunting the Hunter").

Jess

Some other highlights of the paper: Cosmopolitodus/Isurus hastalis is reclassified as a species of Carcharodon, and the "transitional" species is now Carcharodon hubbelli.

I'm good friends with Mike Gottfried - he visited here in May to work on a Cretaceous tarpon fossil; it was good fun. I got the impression that he's rather sick of the whole debate, and prefers to discuss other subjects he finds more interesting. Any way, he's a very friendly, approachable guy. We agree to disagree, and leave it at that.

Edited November 24, 2012 by siteseer

[siteseer]

Yes, that was one of the points of evidence Gottfried et al (1996) used to counter the proposal that the great white evolved from hastalis. They did not bother to check if that was a reliable indicator in the modern species. The rest of the "Carcharodon megalodon" argument was always a collection of questionable specimens, contrived charts, and bad hand drawings.

Proponents of megalodon ---> Carcharodon point at the 3rd upper anterior (sometimes referred to as an intermediate) tooth inclined mesially (i.e,, reversed) as the key evidence. The reasoning is that in Isurus, it is inclined distally. This specimen shows a mesially inclined 3rd upper anterior. What is continuously overlooked is that on rare occasion, modern Carcharodon jaws will have that tooth distally inclined as well.

Here is a juvenile dentition image which has been artificially flattened (image processing). Note the angle of the 3rd upper tooth.

[Paleoc]

The other evidence that Gottfried and Purdy point to (other than the reversed 3rd tooth which as pointed out in the forum is not proper evidence) is the existence of a Carcharodon tooth taken out of zone-10 in the Calvert formation. I have seen this tooth and collected teeth from that location. Zone-10 was a pupping ground for megalodons and teeth from newborn megalodons are found there. These teeth (I have some) are about the size of teeth from sub-adult Carcharodons, so I estimate that the newborn megs were around 7 feet give or take a foot. The other noteworthy items about the teeth are that they are fairly thin (much like Carcharodon) and the bourlette is less than onion-skin thin, usually poorly preserved and/or eroded away, giving the impression that these are Carcharodon teeth. Such is the case with the alleged zone-10 Carcharodon. It is a juvenile megalodon. But as in the case of the reversed tooth, they have used this erroneous conclusion as evidence.