Onchosaurus

[readinghiker]

Does anyone have a good picture of an onchosaurus oral tooth?  

 

Thanks!

[Al Dente]

7 hours ago, readinghiker said:

Does anyone have a good picture of an onchosaurus oral tooth?  

 

Thanks!

 

The only published pictures I'm aware of are from the Hosta Tongue paper by Jim Bourdon. Here are the photos and reference.

 

 

[siteseer]

I would add only that the teeth are questionably identified as Onchosaurus because they differ from other sclerorhynchid teeth from there in most cases just because they are significantly larger and partial rostral spines have been found from there.  They are also very similar to teeth suspected to be those of Onchosaurus found at Cretaceous marine sites in North Africa where spines are also known.

 

That is one rare animal.  There was one very unusual rostral spine from Morocco that one of the Tucson dealers had about 15-20 years ago though I'm not sure that was an Onchosaurus.  It would be likely too old for the phosphate layers but there are Campanian sites in Morocco that yield sawfish remains.  Maybe someone else remembers. 

 

Jess

[readinghiker]

Jess,

 

  Thanks for the reply.  I am aware of Bourdon's bulletin (I was the tail end author on this, and drew the cover), but he only assumes that this tooth is Onchosaurus.  On Elasmo.com,

he states that he had had personal conversations with Cappetta, who also assumes some teeth were Onchosaurus simply because they were associated with a rostral tooth.  The site I am working on has thousands of small teeth, collected by ants, and so the rostral tooth and its peduncle would be far too large for them to haul around.  So without the peduncle or the barbed rostral tooth, an isolated tooth doesn't have much to back it up.  And so, since our museum bulletin was published ten years ago, I was hoping that someone had found a definitive Onchosaurus oral tooth for me to compare what I have found to.  I guess I am going to have to simply write cf. Onchosaurus pharao when this fauna gets written up as another NMMNH bulletin at the beginning of next year.  I have included a photo of the lone tooth that might be Onchosaurus.  What do you think?

 

Thanks again,

Randy

[siteseer]

Hi Randy,

 

That tooth does resemble Pucapristis so I get the logic that an oral tooth that looks like Pucapristis and less like other known sclerorhynchids found in association with Onchosaurus rostral spines is likely an oral tooth of Onchosaurus.  It would be great if Onchosaurus had a species from Lebanon where they find skeletons.  It might have been a deeper water animal only occasionally entering the Tethys or the Western Interior Sea.

 

Years ago, Marcel and I sent him some comments on his Sharktooth Hill Bonebed page on elasmo and he made us co-authors on it  I still get solstice greetings from him.  Nice guy.

 

Henri Cappetta has always been open to discussions.  You should contact him.

 

I always liked that cover drawing...the action shot of Scapanorhynchus.  I think it could inspire a spaceship design.

 

Jess

[readinghiker]

Jess,

  Thanks for your response (and the complement to my cover!).  Sorry about the lapse in replying.  Things have been tough around here (I lost my little brother to a motorcycle accident).  But I am back to the selachians.  I just finished writing up this tooth, and I am calling it Onchosaurus  radicalis.  I am calling this radicalis rather than pharoa (the other valid Onchosaurus species), because pharao is known only from the Campanian and Maastrichtian, and this is older....Coniacian.  I am about to write up two more schlerorhynchids...

Ischyrhiza avonicola and Ischyrhiza mira,  both from the Cabezon site.

 

Randy

[Al Dente]

2 hours ago, readinghiker said:

 I am about to write up two more schlerorhynchids...

Ischyrhiza avonicola and Ischyrhiza mira,  both from the Cabezon site.

Sorry about your brother. Did you find any oral teeth of I. avonicola? I’m very skeptical of that species. I think people are confusing denticles from the side of head of other sawfish species with true rostral teeth. Here’s an illustration that shows both rostral teeth and the denticles I’m referring to. This is Sclerorhynchus from Lebanon. I believe I. mira had similar.

 

 

 

 

 

Edited June 23, 2021 by Al Dente

[readinghiker]

No oral teeth.  I am comparing the teeth that I have with that of Welton and Farrish.  The teeth I have have the squat flared roots and the bumpy basal end of the short enamel crown.

What do the roots of the denticles on S.atavus look like?  Of all the denticles that I have found for the various selachians, the roots are very shallow.  The I. avaonicola roots, at least as shown by Welton, have the flared bi-lobed features that other schlerorhynchids have.

[Al Dente]

17 hours ago, readinghiker said:

What do the roots of the denticles on S.atavus look like?

 

Here's a close up of the same specimen in the drawing that I posted. This is from the shark-references.com website. It shows roots that are star shaped.

 

 

[Al Dente]

I search through some of my references for I. avonicola. It appears in numerous papers over a wide period of time and was found in freshwater to marine environments. I find them in the Maastrichtian Peedee Formation and possibly some older formations here in North Carolina. I find the typical bilobed root form plus other shapes that may or may not be the same thing. 

[siteseer]

On 6/23/2021 at 6:34 AM, readinghiker said:

Jess,

  Thanks for your response (and the complement to my cover!).  Sorry about the lapse in replying.  Things have been tough around here (I lost my little brother to a motorcycle accident).  But I am back to the selachians.  I just finished writing up this tooth, and I am calling it Onchosaurus  radicalis.  I am calling this radicalis rather than pharoa (the other valid Onchosaurus species), because pharao is known only from the Campanian and Maastrichtian, and this is older....Coniacian.  I am about to write up two more schlerorhynchids...

Ischyrhiza avonicola and Ischyrhiza mira,  both from the Cabezon site.

 

Randy

 

Randy,

 

I'm very sorry to hear about the loss of your little brother.  I'm the oldest so I know what it's like to have little brothers and to feel the responsibility of keeping an eye on them.  You can't do that when they're older and have kids of their own.  I hope you're remembering good times as you deal with the loss.

 

I. avonicola was found at the Bowie site, MD as well.

 

You can try contacting David Ward too.

 

Jess