Dentitions

[MikeDOTB]

Hello everyone, its been awhile since I started a topic, and my current curiousity is shark dentitions. So I was going through the site trying to find pictures and thought I would make it a topic. BMoreFossil recently posted a few dentitions he had put together (My link) and I am sure there are more out there. So if you have ever tried putting together a dentition of shark together, how bout posting a picture. Doesnt matter what shark species, post them all!

Online research led me to this link: http://www.elasmo.com/genera/reconstruct/the_recon.html

Which is great, but it only shows a few of the many sharks out there.

So please, post your dentitions!

[Tony Eaton]

Bmorefossil has some impressive dentitions or dental series. I've been working on Cretoxyrhina, Cretodus, and Cretalamna dental series, at least to the point that I can denote what odd ball teeth are possibly from other shark genus (usually I just place teeth over dental series from Welton and Farish "Collector's Guide ... of Texas") The example I have below is from just taping teeth over a resized printout from Elasmo from Jim Bourdon. I probably don't have enough teeth from any one place for a complete artificial dental series from any one species/dentition. I've been thinking about "photoshopping" a dental series where I can resize or reverse teeth or even duplicate them as needed (although obviously the accuracy goes down with each alteration).

Edited June 11, 2011 by Tony Eaton

[MikeDOTB]

Bmorefossil has some impressive dentitions or dental series. I've been working on Cretoxyrhina, Cretodus, and Cretalamna dental series, at least to the point that I can denote what odd ball teeth are possibly from other shark genus (usually I just place teeth over dental series from Welton and Farish "Collector's Guide ... of Texas") The example I have below is from just taping teeth over a resized printout from Elasmo from Jim Bourdon. I probably don't have enough teeth from any one place for a complete artificial dental series from any one species/dentition. I've been thinking about "photoshopping" a dental series where I can resize or reverse teeth or even duplicate them as needed (although obviously the accuracy goes down with each alteration).

Sweet, I dont know much about the cretaceous sharks of Texas, that looks awesome! I do know that shark teeth are a rarer find there though. How long did it take you collecting to put that together? Thanks for posting!

[Tony Eaton]

Thanks! :-) Well, it is a humble start for me. This is about a years worth of teeth from one location. I have the other side too, but missing a few teeth so it looks rather incomplete. The anterior teeth are more common, the small posterior teeth are tough.

[MikeDOTB]

Thanks! :-) Well, it is a humble start for me. This is about a years worth of teeth from one location. I have the other side too, but missing a few teeth so it looks rather incomplete. The anterior teeth are more common, the small posterior teeth are tough.

Yeah I have noticed that with a lot of the teeth I find as well, the lowers and posteriors are the hardest to find. I find a lot of Squalicorax Pristodontus teeth and wanted to put a dentition of those together, but havnt been able to locate any examples yet to base mine on...

[Tony Eaton]

Here are two more Upper Cretaceous, Upper Middle Cenomanian artificial partial dental series that I've been working on. The first, Cretodus semiplicatus, is fairly accurate I think with a few suspect posterior teeth as filler perhaps.

The second is perhaps a mix of Cretoxyrhina "mantelli" and Cretoxyrhina "denticulata"??? Notice the variation of thin cusps vs. thick cusps, curved lateral posterior crowns vs. straight or bent ones, prominent cusplets vs. missing cusplets. I'll try to put together some "purer" dental series when I get a chance but I probably won't have enough tooth positions.

Edited June 27, 2011 by Tony Eaton

[MikeDOTB]

Those are awesome thanks for posting them. Now the "Mantelli" are the predescors to the Mako? At least I have heard that somewhere.

[Tony Eaton]

I've heard Cretoxyrhina mantelli be compared to Mako sharks. They sure look similar. I'm just not sure what is in the fossil record at the end of the Cretaceous that would be the missing link. Cretoxyrhina seem to vanish with no obvious replacement?

[siteseer]

The quick answer is no. Cretoxyrhina died out by the Campanian (roughly 70-75 million years ago). I have a tooth from the Sulphur River (an apparent Ozan Marl tooth which is Campanian) which looks like a Cretoxyrhina but because it is rather water-worn, I think it could have been reworked from an older formation. There are no makos known from the Maastrichtian (65-70 million years ago - the last five million years of the Cretaceous.

There are no makos known from the Paleocene (10 million years) nor from the first 5 million years of the Eocene. That's a big time block of missing makos if Cretoxyrhina is the ancestor. Even if you tried to link mako-like species across that time, you still have intervals of at least 10 million years with no candidates known from the fossil record so you're still left with the Cretoxyrhina-Isurus idea being unlikely.

Isurus praecursor appears in the Middle Eocene and is the earliest known mako. There was a species called I. schoutedeni (Late Paleocene) but it has more recently been reassigned to Cretalamna. The genus Isurolamna (Late Paleocene-Oligocene) appears to be ancestral to Isurus although some might say Cretalamna could be the direct ancestor.

Now the "Mantelli" are the predescors to the Mako? At least I have heard that somewhere.

[Nandomas]

This is really a nice project. Thank Tony for sharing it with us

[MikeDOTB]

The quick answer is no. Cretoxyrhina died out by the Campanian (roughly 70-75 million years ago). I have a tooth from the Sulphur River (an apparent Ozan Marl tooth which is Campanian) which looks like a Cretoxyrhina but because it is rather water-worn, I think it could have been reworked from an older formation. There are no makos known from the Maastrichtian (65-70 million years ago - the last five million years of the Cretaceous.

There are no makos known from the Paleocene (10 million years) nor from the first 5 million years of the Eocene. That's a big time block of missing makos if Cretoxyrhina is the ancestor. Even if you tried to link mako-like species across that time, you still have intervals of at least 10 million years with no candidates known from the fossil record so you're still left with the Cretoxyrhina-Isurus idea being unlikely.

Isurus praecursor appears in the Middle Eocene and is the earliest known mako. There was a species called I. schoutedeni (Late Paleocene) but it has more recently been reassigned to Cretalamna. The genus Isurolamna (Late Paleocene-Oligocene) appears to be ancestral to Isurus although some might say Cretalamna could be the direct ancestor.

Wow great information Siteseer, I have been pretty curious about the Mako line. The oldest of the Mako line I had found were I. Praecursor (Eocene). I guess i will have to look into I. Schoutedeni as well.

[cowsharks]

Here are two more Upper Cretaceous, Upper Middle Cenomanian artificial partial dental series that I've been working on. The first, Cretodus semiplicatus, is fairly accurate I think with a few suspect posterior teeth as filler perhaps.

The second is perhaps a mix of Cretoxyrhina "mantelli" and Cretoxyrhina "denticulata"??? Notice the variation of thin cusps vs. thick cusps, curved lateral posterior crowns vs. straight or bent ones, prominent cusplets vs. missing cusplets. I'll try to put together some "purer" dental series when I get a chance but I probably won't have enough tooth positions.

Tony, instead of using tape to hold the teeth down, have you considered using double-sided tape? Lay a section of tape out on your sheet of paper so one side will stick onto the paper, then place your teeth on top of the tape. If you use the elasmo dentitions as ref, you could always print one out and tape it above or below your specimens. Just a thought.

Daryl.

[Tony Eaton]

Thanks for those that looked at the teeth I posted. Daryl, thanks for the suggestion of the double sided tape. For me the next step will probably be some sort of virtual solution.