Help on this unknown lamniform?

[readinghiker]

Hopefully, this will be the last time I post on this fauna until I announce the finished publication!

I had originally identified this as a cretodus, but after reviewing Everhart and Welton, I am having very serious doubts as to

the validity of this ID.  The teeth are both labially and lingually striated.  The lingual striations look totally different than the pattern

found on the scapanorhynchids.  The teeth have accessory cusplets, sometimes two on a side.  The base of the teeth are more robust than that

of scapanorhynchids, too.  As you can tell by the photos, even the worn teeth have pronounced striations.  Any help at to identifying these teeth to genus (maybe even species?) level would be wonderful!  Thanks!

[siteseer]

It's tough when the tooth is incomplete and worn.  I think they could both be orectolobiforms.  That last tooth looks the one you posted before.  From those views provided, it looks like the root was thicker.

[fossilsonwheels]

I agree with Jess that Orectolobiformes of some kind is a possibility. 

[Al Dente]

Hard to ID without the root but some lamniformes have striated posterior teeth while their more anterior teeth are smooth. Carcharias is one example where this can occur.

[readinghiker]

Thanks to those who have replied...the hunt for an answer goes on!  I will definitely check out the orectolobiformes.

 

Randy

 

[readinghiker]

To all the great people on the forum.  I think that I have solved the issue...it appears to be Cretodus cf. semplicatus.  I was looking at Welton

and Everhart's description of Cretodus crassidens, which does not mention or picture any striations.  I should have concentrated on Cappetta's

Handbook of Paleoichthyology (3E),  where on page 255 he describes the above teeth perfectly, and backs up his description with photos that

are almost identical to the above photos.  Thanks again!  I will let the forum know when the Bulletin will come out. 

[ThePhysicist]

45 minutes ago, readinghiker said:

To all the great people on the forum.  I think that I have solved the issue...it appears to be Cretodus cf. semplicatus.  I was looking at Welton

and Everhart's description of Cretodus crassidens, which does not mention or picture any striations.  I should have concentrated on Cappetta's

Handbook of Paleoichthyology (3E),  where on page 255 he describes the above teeth perfectly, and backs up his description with photos that

are almost identical to the above photos.  Thanks again!  I will let the forum know when the Bulletin will come out. 

Can you link Welton/Everhart's description of C. crassidens? Amalfitano et al. (2022) clearly describe basal costulae/striae on the lingual and labial faces of C. crassidens. Would you also mind showing Cappetta's description and photos of C. semiplicatus? 

[readinghiker]

On 9/30/2022 at 9:06 PM, ThePhysicist said:

Can you link Welton/Everhart's description of C. crassidens? Amalfitano et al. (2022) clearly describe basal costulae/striae on the lingual and labial faces of C. crassidens. Would you also mind showing Cappetta's description and photos of C. semiplicatus? 

Sorry about the late reply, been kind of busy.

  

From Welton:

 

“”crown faces smooth except for short longitudinal ridges and enamaloid plications at the crown foot on cusp and cusplets…This species is characterized by its large, massive teeth, general smooth crown

faces with ridges only at the crown foot…”  Fossil Sharks and Rays from the Cretaceous of Texas  Page 98

 

From Everhart:

 

“The central cusp shows many minute, wrinkle-like striations along the base. Lateral cusplets have a broad base and a triangular shape, but are much smaller than the central cusp.”  Mike Everhart,  Oceans of Kansas website (oceansofkansas.com)

 

 

From Cappetta:

 

“The teeth (up to 4 cm high) of the genus have a triangular rather narrow cusp in anterior files and never very broad in lateral files.  The labial face is barely convex,  the lingual one is more strongly cambered often with a distinct median flattening; it bears very strong and prominent vertical folds that can cover half the height of the cusp.  The labial face also bears many closer but shorter folds.  The folds of the lingual face ascend less high on the cusp on the lateral teeth.” Pages 253-254 Handbook of Paleoichthyology 3E

 

The difference between the striations of crassidens and semiplicatus is that crassidens striations are minute and do not reach up too far from the base of the cusp.  Semiplicatus striations are very pronounced and can go up at least halfway up the lingual crown and at least a quarter way up the labial side of the crown.  Unfortunately, I was not able to get a copy of the pictures in Cappetta's work.

Thanks for your response!

Randy

[siteseer]

On 9/30/2022 at 6:58 PM, readinghiker said:

To all the great people on the forum.  I think that I have solved the issue...it appears to be Cretodus cf. semplicatus.  I was looking at Welton

and Everhart's description of Cretodus crassidens, which does not mention or picture any striations.  I should have concentrated on Cappetta's

Handbook of Paleoichthyology (3E),  where on page 255 he describes the above teeth perfectly, and backs up his description with photos that

are almost identical to the above photos.  Thanks again!  I will let the forum know when the Bulletin will come out. 

 

Did you find larger, more clearly-identifiable specimens of Cretodus at the locality?

[ThePhysicist]

20 hours ago, readinghiker said:

From Welton:

 

“”crown faces smooth except for short longitudinal ridges and enamaloid plications at the crown foot on cusp and cusplets…This species is characterized by its large, massive teeth, general smooth crown

faces with ridges only at the crown foot…”  Fossil Sharks and Rays from the Cretaceous of Texas  Page 98

 

From Everhart:

 

“The central cusp shows many minute, wrinkle-like striations along the base. Lateral cusplets have a broad base and a triangular shape, but are much smaller than the central cusp.”  Mike Everhart,  Oceans of Kansas website (oceansofkansas.com)

 Ah, I thought Welton and Everhart had done a paper together. A couple of notes: 1. Everhart's "C. crassidens" was misidentified, and later described as a new species, C. houghtonorum (Shimada & Everhart (2019)). 2. Similarly, Welton and Farish's "C. crassidens" likely represents a different, gracile species since it differs from the type of C. crassidens so much. I recommend if your intention is to publish, to refer to peer-reviewed works for descriptions.

 

Can you rule out genera like Protolamna? Especially for posterior/small incomplete teeth, they could look quite similar. I don't believe a confident ID beyond Lamniformes is possible given the teeth are incomplete. In publishing a bulletin, I would personally be more conservative with ID's until larger, more complete, definitive teeth are found.