Shark Tooth Hill

[Fossil-Hound]

14 hours ago, siteseer said:

 

 

That article is not a full review of the discussion of the proposed origins of the great white shark.  What you are not getting from the writer is that the vast majority of researchers (and longtime amateur collectors for that matter) consider the species hastalis the direct ancestor of Carcharodon carcharias.  The main reason for that is the large number of transitional teeth found in the Early Pliocene of California, Peru, and Chile.  You find teeth that are unserrated (hastalis), then teeth that are weakly-serrated (Carcharodon hubbelli), then teeth that are fully serrated (Carcharodon carcharias) in successive beds.  When you look at enough teeth, you get the idea that hastalis is just an unserrated-toothed great white shark.  The idea that C. carcharias and Carcharocles megaldon were closely-related is an old one that never really had any evidence to support it other than both had rather large to very large teeth that were serrated.  It was something that seemed obvious but not examined.  There have never been any proposed transitional teeth for megalpdon-carcharias.  In fact with the genus Carcharocles now considered by a growing number of researchers to be a subgenus or junior synonym of Otodus, even more taxonomic distance opens up between megalodon and carcharias.  Otodus dates back to the Early-Middle Paleocene while the ancestors of Carcharodon become murky going back through the Oligocene and Eocene - perhaps back to Isurolamna.

 

You'd have to read:

 

https://www.researchgate.net/publication/253767853_Tracing_the_ancestry_of_the_great_white_shark_Carcharodon_carcharias_using_morphometric_analyses_of_fossil_teeth

 

https://www.researchgate.net/publication/253767853_Tracing_the_ancestry_of_the_great_white_shark_Carcharodon_carcharias_using_morphometric_analyses_of_fossil_teeth

 

And the one that started it all though it was more of an aside within a wider discussion (not sure it's available as a pdf):

 

Muizon, C. de, and T. J. DeVries. 1985. Geology and paleontology of late Cenozoic marine deposits in the Sacaco area (Peru). Geologische Rundschau 74:547–563.

 

Also, here is a Fossil Forum thread in which Boesse discusses the hastalis-carcharias transition in northern California:

 

http://www.thefossilforum.com/index.php?/topic/24721-mako-to-great-white/#comment-270855

 

Also, read Ward and Bonavia (2001) for comments on Purdy et al. (2001):

 

https://www.researchgate.net/publication/280316614_Additions_to_and_a_review_of_the_Miocene_Shark_and_Ray_fauna_of_Malta 

 

Jess

This is what I was getting at. There's no direct correlation between Megalodon and Carcharias whereas the modern Mako and Great White appear to share a common ancestor in C. hastalis.

 

Read this: