A Couple of Shark Teeth. Cretodus houghtonorum and Turonian Galeorhinus?

[Mikrogeophagus]

Hey everyone,

 

Just a quick ID post for help in pinning down what exactly these couple of teeth are. Up first is a broken crown to a tooth I found while processing South Bosque material from Central TX for a pet project of mine. It's Turonian in age and looks similar to some small Carchariniformes teeth I've found at the Whiskey Bridge. Note that when I found this tooth, I had not yet visited the Whiskey Bridge, so I am certain this is not a product of cross contamination. Anyways, it's unlike the other specimens I have from the South Bosque and I am struggling to find a genus that matches its shape other than Galeorhinus. Carchariniformes were present in the Mesozoic and Galeorhinus is known all the way back into the Cenomanian, but ones this old are very rare so I am hesitant. I am wondering if any knows another more likely genus for this Turonian tooth?

 

 

The second tooth is definitely Cretodus, but I am trying to pin down a species. It came from the Atco (Coniacian) which is known to produce Cretodus crassidens, but I have recently learned of another species, Cretodus houghtonorum, that is also in the area and a candidate. Unfortunately, I do not have access to the paper describing C. houghtonorum so it is difficult for me to figure out how to differentiate the two, but just off of secondhand knowledge I believe this one may be C. houghtonorum because of its more gracile non-ovular cusp. The wrinkling on the labial face is very pronounced and travels farther up the cusp than on my C. semiplicatus specimen from the Cenomanian. On the lingual side, the wrinkling is very short whereas they travel much farther on the C. semiplicatus. The root on the suspected C. houghtonorum is extremely pronounced and almost hangs over the cusp and cusplets. Wish I had a C. crassidens to compare to, but the C. semiplicatus is all I've got for now. Luckily they are very similar in mouth position so it's easy to spot differences.

 

Left is tooth in question; Right is C. semiplicatus specimen

 

Tooth in question

 

C. semiplicatus

 

@ThePhysicist @Al Dente @MarcoSr

 

If you know any other shark experts who could help, feel free to ping them in the replies  

 

Thanks!

[Al Dente]

19 hours ago, EPIKLULSXDDDDD said:

Carchariniformes were present in the Mesozoic and Galeorhinus is known all the way back into the Cenomanian, but ones this old are very rare so I am hesitant.

 

According to the www.elasmo.com website (for Galeorhinus): "Cappetta (1987:115) indicated the genus extends back to the Lower Turonian (Upper Cretaceous) and has been reported from Europe, Africa and North America."

[Mikrogeophagus]

3 hours ago, Al Dente said:

According to the www.elasmo.com website (for Galeorhinus): "Cappetta (1987:115) indicated the genus extends back to the Lower Turonian (Upper Cretaceous) and has been reported from Europe, Africa and North America."

I did find one instance of Galeorhinus from the Cenomanian (A New Shark Species of the Genus Galeorhinus (Chondrichthyes, Triakidae) from the Cenomanian of the Lower Volga River Basin), but it's not from North America. Visually, does this seem like Galeorhinus to you? Or is there another genus it reminds you of? Just not much info on Turonian Galeorhinus to go with out there, so I'm wondering if there's a better documented genus I've overlooked that could explain this specimen. 

[Al Dente]

It looks similar to the younger Galeorhinus that I’m familiar with.

[MarcoSr]

The below tooth looks similar to both Galeorhinus and Palaeogaleus teeth that I see in the Paleocene of MD and the Eocene of VA.

 

 

 

 

 

I really can't help with your other tooth.

 

Marco Sr.

[ThePhysicist]

On 3/20/2023 at 4:00 PM, EPIKLULSXDDDDD said:

Unfortunately, I do not have access to the paper describing C. houghtonorum so it is difficult for me to figure out how to differentiate the two

PM sent

 

Here are the upper and lower lateral tooth files for C. houghtonorum:

^ https://doi.org/10.1080/02724634.2019.1673399

 

The crown on yours seems narrower (could be an ontogenetic difference), the lingual root protuberance more pronounced (nearly half the labio-lingual width), and the labial costulae proceed further apically (nearly half the crown height). Call it what you wish, but I personally would not lean towards C. houghtonorum, and would leave it as an indeterminate species.

[siteseer]

On 3/20/2023 at 3:00 PM, EPIKLULSXDDDDD said:

Hey everyone,

 

Just a quick ID post for help in pinning down what exactly these couple of teeth are. Up first is a broken crown to a tooth I found while processing South Bosque material from Central TX for a pet project of mine. It's Turonian in age and looks similar to some small Carchariniformes teeth I've found at the Whiskey Bridge. Note that when I found this tooth, I had not yet visited the Whiskey Bridge, so I am certain this is not a product of cross contamination. Anyways, it's unlike the other specimens I have from the South Bosque and I am struggling to find a genus that matches its shape other than Galeorhinus. Carchariniformes were present in the Mesozoic and Galeorhinus is known all the way back into the Cenomanian, but ones this old are very rare so I am hesitant. I am wondering if any knows another more likely genus for this Turonian tooth?

 

 

 

@ThePhysicist @Al Dente @MarcoSr

 

If you know any other shark experts who could help, feel free to ping them in the replies  

 

Thanks!

 

When you ask about a tooth, you need to at least provide the labial and lingual faces as you did with the Cretodus.  That said, I would say it's too big and too old to be a Palaeogaleus and you would need to have at least most of the root to be sure.  I think that leaves Galeorhinus.

 

As for the Cretodus, I don't know how anyone separates that into species.  I've seen so many weird ones and it's not a common tooth.  There are hunters who have several but it took a long time to find them.  They are uncommon enough that they tend to keep every piece they find.

 

 

[MarcoSr]

13 hours ago, siteseer said:

 

When you ask about a tooth, you need to at least provide the labial and lingual faces as you did with the Cretodus.  That said, I would say it's too big and too old to be a Palaeogaleus and you would need to have at least most of the root to be sure.  I think that leaves Galeorhinus.

 

As for the Cretodus, I don't know how anyone separates that into species.  I've seen so many weird ones and it's not a common tooth.  There are hunters who have several but it took a long time to find them.  They are uncommon enough that they tend to keep every piece they find.

 

 

 

See the below excerpts from Cappetta 2012.  Cappetta is only showing Palaeogaleus going back to the Cretaceous Campanian.  However, the researchers have been changing Palaeogaleus and Galeorhinus species genera IDs back and forth because there doesn't seem to be a firm consensus on the two genera.

 

 

 

 

 

Marco Sr. 

[Mikrogeophagus]

On 3/23/2023 at 6:43 PM, ThePhysicist said:

Call it what you wish, but I personally would not lean towards C. houghtonorum, and would leave it as an indeterminate species.

I see your point here. I did end up sending Shimada an email several days ago asking about this tooth, but seems like I won’t get a response sadly. I also noted the pronounced lingual root protuberance you mentioned in the email. Another discrepancy from C. houghtonorum was that the basal concavity of my tooth showed a U shape as opposed to the expected V shape. Seems there’s still a lot of work to be done documenting these species

[Jared C]

On 3/27/2023 at 6:34 PM, EPIKLULSXDDDDD said:

Seems there’s still a lot of work to be done documenting these species

Indeed. I find this thread interesting because I also have a Cretodus from washed out from what looks like the basal atco that is completely mysterious to me. It's also different from yours. I'll take some photos when I'm back home.