Identification Challenge For Bone Collectors No. 7

[Harry Pristis]

Here's a ID challenge for shark tooth collectors. There have been some recent posts about the species differences between Carcharocles megalodon and Carcharocles chubutensis. The posts relied on the absence or presence of cusplets for an ID.

These cusplets do occur with C. megalodon teeth, specifically on the teeth of juvenile sharks of that species. (These lateral cusplets occur on juvenile Carcharodon carcharias, great white shark, teeth also.) The geological age of the specimen then becomes critical to identifying a juvenile specimen as C. chubutensis versus C. megalodon.

Bretton Kent in his FOSSIL SHARKS OF THE CHESAPEAKE BAY REGION (1994) gives a reasoned argument that these ARE distinct species, while he discusses the unknowns of this taxonomic challenge.

Kent asserts that small (younger sharks) examples from each species are found in the same sediments, BUT he identifies C. chubutensis as an Early through Middle Miocene species in the Chesapeake Bay exposures. He writes that this species also has been reported from Argentina, Germany, and North Carolina. No mention is made of the Late Miocene phosphates of South Central Florida.

Here are some already-identified shark teeth for illustration. I have included an image of a mystery shark tooth for your consideration. A golden kudo to the first one to correctly identify this shark.

--------------Harry Pristis

[Gatorman]

Palaeocarcharodon orientalis?

[Harry Pristis]

Palaeocarcharodon orientalis?

Bingo! Very good, Anson! This is a very large specimen of the Paleocene relative of the various species of Carcharocles. This is Paleocarcharodon orientalis (=P. landenensis) from the phosphate mines near Khouribga, Morocco.

While this example comes from Morocco, these sharks were worldwide in distribution. It is the Paleocene marine sediments that are hard to find exposed.

A golden kudo to Anson!

-------Harry Pristis

[worthy 55]

Go ahead Anson !!!!!! :Thumbs-up: