Oxford Clay Teeth

[Othniel C. Marsh]

Below are two teeth from the Callovian of the Oxford Clay. The left was identified as Hypsocormus tenuirostris, and the right one Teleosaurus sp. I thought it would be worth verifying both IDs, given how difficult some Jurassic marine reptile teeth are to identify. It is my understanding that @pachy-pleuro-whatnot-odon has great expertise with regards to Jurassic teeth. What do you make of them?

 

 

Thanks in advance for any guidance

Othniel

[Tidgy's Dad]

Can't help, but those are a couple of very nice and interesting teethies.

[Othniel C. Marsh]

Thanks @Tidgy's Dad!

[pachy-pleuro-whatnot-odon]

The tooth on the right certainly does look like a pachycormid fish fang, although I'm far from enough of a fish specialist to be able to tell you whether it might be Hypsocurmus sp.. However, compare with the teeth in below thread:

 

 

 

Likewise, the second, smaller tooth does, at first glance, indeed appear teleosaurid. However, for proper identification I'd need beter quality photographs that would show the striae and carinae more clearly. Again, have a look at the below thread for further information and comparison:

 

 

 

[Othniel C. Marsh]

How many pachycormiforms are known from the Oxford Clay? The Wikipedia page on the formation seems to suggest there are only 3, but lists such as the one in question are not always complete. However, I have found an overview of the fossils of the Oxford Clay that suggests that there are 4, but it was published in 1991 and as such I'd imagine it's at least a little outdated. Assuming either of these lists is correct, identifying the pachycormid tooth suddenly becomes much easier.

 

The overview in question:

 

https://www.geokniga.org/bookfiles/geokniga-fossils-oxford-clay-1991.pdf

Edited March 16 by Othniel C. Marsh

[Othniel C. Marsh]

Here are some (hopefully) better photos of the teleosaurid tooth, @pachy-pleuro-whatnot-odon:

 

Edited March 16 by Othniel C. Marsh

[pachy-pleuro-whatnot-odon]

On 3/16/2024 at 3:03 AM, Othniel C. Marsh said:

How many pachycormiforms are known from the Oxford Clay? The Wikipedia page on the formation seems to suggest there are only 3, but lists such as the one in question are not always complete. However, I have found an overview of the fossils of the Oxford Clay that suggests that there are 4, but it was published in 1991 and as such I'd imagine it's at least a little outdated. Assuming either of these lists is correct, identifying the pachycormid tooth suddenly becomes much easier.

 

The overview in question:

 

https://www.geokniga.org/bookfiles/geokniga-fossils-oxford-clay-1991.pdf

 

Unfortunately, I'm not well-versed enough with fish teeth to be able to help you identify you particular specimen. I'd say, however, that it's definitely one of the larger ones, so Hypsocormus sp. does seem like a good candidate.

 

On 3/16/2024 at 2:20 PM, Othniel C. Marsh said:

Here are some (hopefully) better photos of the teleosaurid tooth, @pachy-pleuro-whatnot-odon:

 

 

Unfortunately, both of these photograph still aren't really clear, although they are clear enough to show the carina in the second photograph, as well as how the rest of the striae interact with the carina, as this is what allows reaffirmation that this is indeed a teleosauroid crocodile tooth. Due to the similarity of their teeth, it's traditionally been difficult to distinguish Teleosaurus sp. from 'Steneosaurus', although there are some minor differences which allow distinction within the later group (see here). Generally speaking, though, these teeth are non-diagnostic. With 'Steneosaurus' leedsi and 'S.' durobrivensis being the only two species of teleosaur described from the Oxford Clay, however, it's likely this tooth would be attributable to either of them. In the past, you'd have been able to register this uncertainty by ascribing the tooth to "Steneosaurus sp.", but this is no longer possible since the genus 'Steneosaurus' is no longer considered valid and the two species are now known as Charitomenosuchus leedsi and Neosteneosaurus edwardsi, respectively. As such, "machimosauridae indet." would be the best way to refer to them - although this seems unsatisfactory for the absence of durophageous adaptations in this particular tooth. The best way to work around this limitation might be to describe the tooth as "teleosauroidea indet.".

 

Hope this helps!

Edited March 18 by pachy-pleuro-whatnot-odon

[Othniel C. Marsh]

I thought Mycterosuchus nasutus and Lemmysuchus obtusidens where also known from the Oxford Clay, but that has no bearing on the identification of the tooth. Your help is much appreciated, @pachy-pleuro-whatnot-odon.

[pachy-pleuro-whatnot-odon]

14 minutes ago, Othniel C. Marsh said:

I thought Mycterosuchus nasutus and Lemmysuchus obtusidens where also known from the Oxford Clay, but that has no bearing on the identification of the tooth. Your help is much appreciated, @pachy-pleuro-whatnot-odon.

 

Looking these two up, it seems that they were around at the time and may, indeed, even have been recovered from the Callovian part of the Oxford Clay. As my main interest in marine crocodiles lies in how to differentiate their teeth from those of other marine reptiles, I'm not altogether to familiar with the new formal variety that's been recognised. At the same time, my earlier point on the difficulty of distinguishing the teeth of the one species from the next still hold...

[Othniel C. Marsh]

22 minutes ago, pachy-pleuro-whatnot-odon said:

At the same time, my earlier point on the difficulty of distinguishing the teeth of the one species from the next still hold...

 

I didn't intend to suggest otherwise. Apologies for the misunderstanding.

Edited March 18 by Othniel C. Marsh

[pachy-pleuro-whatnot-odon]

3 hours ago, Othniel C. Marsh said:

I didn't intend to suggest otherwise. Apologies for the misunderstanding.

 

No worries. All's good