Weird Cretaceous vertebrates

[Anomotodon]

Hi everyone! Found these two specimens in the Upper Albian Burim formation in Ukraine. Would appreciate any help with ID!

 

1. So this 1.2 cm tooth is as basic as they get - no carinae, no enamel ornamentation (enamel is there by the way), circular cross section and this really weird apical twist. When I found it in the sieve I thought it was a Polycotylid plesiosaur, but lack of striations is not typical of plesiosaurs. Can't find a large fish without carinae either (Icthyodectids, Enchodontids, Protosphyraena, Pachyrhizodus and other pachycormids all have carinae), although enamel is quite thick and definitely looks more reptilian. Crocs also have carinae. Apparently, Ctenochasmatid pterosaurs can have all of these features, but this tooth is quite robust for a pterosaur. I am confused...

 

 

For comparison, other stuff from this locality left to right: Icthyodectid, Protosphyraena, Enchodus, Platypterygiine ichthyosaur, Polycotylid, Elasmosaurid tooth tip and Ornitocheiroid pterosaur

 

 

2. Well, for this one I am pretty sure it is a teleost of some kind. At first I thought it is a very worn tooth in a jaw section, but the overall shape is inconsistent with fish jaw bones. It seems relatively complete, so it would be great if there is anything diagnostic. (6 cm)

 

 

@pachy-pleuro-whatnot-odon @Mike from North Queensland @ anyone else

[pachy-pleuro-whatnot-odon]

Hi Tim,

 

I'm not sure I can really help you with either of these pieces, seeing as field identification within an unfamiliar fauna is quite a few steps removed from providing an ID when your choices in palaeofauna are known and limited... My main focus lies on telling one type of marine reptile remains from the other. But throw something else in the mix and I too get easily confused. As such, I'm really impressed with your identification of this hand-full of teeth, as it's obvious a lot of effort went into it.

 

Having put this disclaimer out of the way, however, I'll try to get this identification going, in hopes others will chime in with their specific expertise...

 

Lets start with my agreement that the tooth does indeed look reptile rather than fish (not that I have a lot of experience with the latter, however). And while the lack of ornamentation, in this case, is odd, it's not unheard of either. Consider, for example, the teeth of the Jurassic Cryptoclidus oxoniensis, which lack any form of ornamentation (see image extracted from figure 5 from Noè, Taylor and Gómez-Pérez [2017] below; left = Muraenosaurus leedsi, middle = Cryptoclidus oxoniensis, right = Tricleidus seeleyi); or the teeth of the Moroccan elasmosaur Zarafasaura oceanis, on which ornamentation is often impossible to make out - though the best specimens exhibit beautiful anastomosing ornament. Likewise, not all ichthyosaurs had teeth with enamel folds, and even those species that did may, as seems to be the case in many other marine reptiles, have lost them as they aged (see my discussion on Temnodontosaurus eurycephalus for an interesting example). That having been said, though, I haven't ever come across an ophthalmosaurid ichthyosaur without enamel folds, even if, as seems to be the case in your specimen, the density of folds may greatly reduce in some specimens (I think I already once showed the specimen from figure 15 from Fischer, Bardet, Guiomar and Godefroit [2014] here , as well as another weird ophthalmosaurid tooth from India taken from figure 7 from Prasad et al. [2017] here - although in the case of the latter specimen, the enamel seems to have worn down somewhat, as this tooth belongs to an ichthyosaur specimen for which teeth with plicidentine folds were also found). Finally, of course, the ornamentation on metriorhynchid teeth seems to have worn off extremely rapidly, to the point that most no longer visibly bear any striations (see here).

 

 

With teleosauridae and machimosauridae being restricted to the Jurassic; the teeth of metriorhynchidae being noticeably laterally compressed; and regular crocodile teeth often looking somewhat like the lingual face of the tooth was lightly pressed into the labial one, I think we can safely rule out the tooth belonging to a crocodilian. Similarly, while the curvature of the tooth crown is most similar to the teeth of ichthyosaurs, it seems highly unlikely that an ophthalmosaurid tooth would be completely devoid of all traces of its enamel folds. Also, the root doesn't seem to taper out, as one would expect beyond the neck-region in ophthalmosaurid teeth. Rather the root looks more crocodilian or plesiosaurian to me, though we've already ruled out the former. Considering plesiosaurs then, the overall morphology of this tooth would not rule this option out, although the tooth would, in that case, need to be positioned towards the back of the jaw. However, the small size of the tooth makes me doubt it would be robust enough to actually be such a plesiosaurian tooth. And, just to be complete, the morphology of tooth and root, as well as the age of your deposits, rule out mosasauroid as well... I'm therefore forced to consider options other than marine reptile. But may be @RuMert and @PointyKnight differ in opinion with me on this...

 

If not marine reptile, but still reptile, then flying reptile might be the outcome. For I believe I've seen rather robust-looking but small teeth from the Moroccan Kem Kem being sold off as pterosaur teeth. Unfortunately, I have little to no knowledge of these kinds of teeth, but may be @msantix can chip in on this part of the discussion. I believe Michael is quite knowledgable on pterosaur material...

 

 

 

As to the bit of bone: as I've got little to no experience with fish material, I wouldn't be able to tell you whether your piece is fish or reptile, although the piece does look somewhat more solid than the few fish bits I've seen. The piece kind of reminds me of a bit of bone I found in the Boulonnais last year, and I suspect yours might be a bit of skull bone too. In my case, however, with the high presence of crocodile remains at the Boulonnais and the help of @caterpillar, it was possible to pin down the suspect (or, rather, group of suspects) and then figure out from there what kind of bit of bone it could be from there. In your case, though, I think this would be much more difficult. But my hunch is it could be from the skull of a large fish, possibly something like Protosphyraena. It's worth mentioning here that @mamlambo found the skull of an Eocene billfish in New Zealand less than a year ago, so it might be worthwhile watching his video on that, if not see if Morne could add something to this discussion...

 

 

 

Your inclusion of Protosphyraena in the fauna of that site seems a bit problematic, by the way, as Wikipedia tells me the species was not yet around in the Albian...! This means that either

• the tooth was identified wrongly;
• the dating of the site is off and we can exclude ichthyosaurs as source for your tooth as they were long extinct during the Coniacian, as well as need to reject mosasaurs as origin on grounds that their tooth morphologies alone don't match your find;
• the tooth was washed in from younger deposits and we're dealing with a palimpsest situation, making species identification harder;
• Wikipedia is lying (but when did it ever do that, right? ); or
• you made an extremely significant discovery there that extends the stratigraphical (if not already geographical) range of the genus.

 

I'm probably way off in my identifications at this point, but lets hope this sparks some discussion

[caterpillar]

Indeed I'm not sure your bit of bone is a croc

[Mike from North Queensland]

No real clue either but the elasmosaur teeth I find have very fine ornamentation so your tooth could be worn elasmosaur and the piece of bone gives me that fish vibe

 

 

[pachy-pleuro-whatnot-odon]

32 minutes ago, Mike from North Queensland said:

No real clue either but the elasmosaur teeth I find have very fine ornamentation so your tooth could be worn elasmosaur and the piece of bone gives me that fish vibe

 

Certainly a possibility, I'd say. A lot of Z. oceanis teeth (to use that as an example again) show only mild, if any, labiolingual compression with the ornamentation being worn off on many. Plesiosaur (sensu lato) would also fit quite nicely with the morphology of the root. The one thing that makes me less inclined to consider the tooth elasmosaurian, however, is the robust nature of the specimen, with most plesiosaurian teeth being both more slender and taller. I also believe the curvature of the tooth would be somewhat more gradual, whereas this tooth has it's main curvature positioned towards the apex. But main be that's just another factor of size...

[RuMert]

@Svetlana

[Anomotodon]

Thanks for your comments everyone!

 

On 8/10/2021 at 5:27 PM, pachy-pleuro-whatnot-odon said:

Certainly a possibility, I'd say. A lot of Z. oceanis teeth (to use that as an example again) show only mild, if any, labiolingual compression with the ornamentation being worn off on many. Plesiosaur (sensu lato) would also fit quite nicely with the morphology of the root. The one thing that makes me less inclined to consider the tooth elasmosaurian, however, is the robust nature of the specimen, with most plesiosaurian teeth being both more slender and taller. I also believe the curvature of the tooth would be somewhat more gradual, whereas this tooth has it's main curvature positioned towards the apex. But main be that's just another factor of size...

 

Well, looks like I will have it as Plesiosauria indet. for now. Checked most major Cretaceous plesiosaurian groups, and couldn't find any teeth without ornamentation other than elasmosaurs from the latest Cretaceous. Only for Leptocleididae I couldn't find any good illustrations or descriptions, it seems that they survived until Albian, maybe their teeth were different from Polycotylid?

 

On 8/10/2021 at 5:28 AM, pachy-pleuro-whatnot-odon said:

Your inclusion of Protosphyraena in the fauna of that site seems a bit problematic, by the way, as Wikipedia tells me the species was not yet around in the Albian...! This means that either

• the tooth was identified wrongly;
• the dating of the site is off and we can exclude ichthyosaurs as source for your tooth as they were long extinct during the Coniacian, as well as need to reject mosasaurs as origin on grounds that their tooth morphologies alone don't match your find;
• the tooth was washed in from younger deposits and we're dealing with a palimpsest situation, making species identification harder;
• Wikipedia is lying (but when did it ever do that, right? ); or
• you made an extremely significant discovery there that extends the stratigraphical (if not already geographical) range of the genus.

 

I'm probably way off in my identifications at this point, but lets hope this sparks some discussion

 

Quite confident Wikipedia is lying here. Protosphyraena was described from a couple of Albian-Cenomanian sites in Italy and Protosphyraena-like teeth are common at this site (which is Albian by the way) and many Cenomanian locations in Russia. I will admit though, I have no idea if there were other large pachycormids with similar teeth around that time, so a question mark might be necessary ?Protosphyraena sp.

[pachy-pleuro-whatnot-odon]

1 hour ago, Anomotodon said:

Well, looks like I will have it as Plesiosauria indet. for now. Checked most major Cretaceous plesiosaurian groups, and couldn't find any teeth without ornamentation other than elasmosaurs from the latest Cretaceous. Only for Leptocleididae I couldn't find any good illustrations or descriptions, it seems that they survived until Albian, maybe their teeth were different from Polycotylid?

 

Plesiosauridae indet. seems a safe identification. As stated above, it's quite possible that the ornamentation normally present on a tooth would've worn off, much as has happened with most Z. oceanis teeth and with those of metriorhynchid crocodiles. The susceptibility to ornamentation wearing off - at least in metriorhynchids - seems, moreover, to vary with species. It's therefore not unimaginable that your tooth belongs to a species that normally would have ornamentation, but that this ornament has worn away. Size of the tooth and age of the individual to which it belonged may both have played a role, as well as there always being the possibility of the tooth being attributable to a previously undescribed species (although this is admittedly less likely). It is also possible that this tooth is a polycotylid one, as, while most polycotylid teeth have quite well-defined striae, those from Goulmima in Morocco only have very fine striations around the base of the tooth on the lingual side, with the buccal side being free of ornament. Then again, those teeth are markedly compressed...

 

Polycotylid tooth from Goulmima: either Thililua longicollis or Manemergus anguirostris

 

It's also good to keep in mind that over the entirety of the Jurassic many plesiosauroid species did not have ornamented teeth. Thus, it cannot be excluded that some descendant species may have similarly had unornamented teeth, for example due to a character-reversal. As to the teeth of leptocleidid plesiosaurs: I have, unfortunately, also not been able to find any good reference material. The below tooth, however, from the Hastings Beds near Bexhill in Sussex, can be attributed to Leptocleidus sp.. And while it appears to have striations under certain light conditions, it is, in practice, free of ornament.

 

 

 

1 hour ago, Anomotodon said:

Quite confident Wikipedia is lying here. Protosphyraena was described from a couple of Albian-Cenomanian sites in Italy and Protosphyraena-like teeth are common at this site (which is Albian by the way) and many Cenomanian locations in Russia. I will admit though, I have no idea if there were other large pachycormids with similar teeth around that time, so a question mark might be necessary ?Protosphyraena sp.

 

Interesting...! I'm not really a fish person, so I wouldn't be aware of any of the discussions surrounding their palaeontological finds either. But it's surprising that the paper about the Italian specimens was already published back in 2017. The authors' aim of making the international community aware of these specimens thus seems to have failed. May be the fossils were too fragmentary or not diagnostic enough, or may be their stratigraphic context could not be ascertained with enough confidence (just a few things that came to mind glancing over the article)...? However, it's strange that if Russia is also yielding older Protosphyraena-remains this is not being picked up upon. May be those remains are simply not described? Or may be there's simply too little scientific exchange going on between individual linguistic research communities?

 

My mentioning of the Coniacian, by the way, was rather with respect to my sketching of the hypothetical situation in which both your identification of the Protosphyraena-tooth would've been correct, as would Wikipedia's assertion that the species' first occurrence is in the Coniacian. For if both statements are assumed to be correct, your site should have to be at the very least Coniacian in age, which would conflict with the presence of an ichthyosaur tooth in the same assemblage. As such, it was not so much an oversight of the age of your site on my part - as I'm well aware it dates to the Albian - but rather me trying to posit a hypothetical explanation to the apparent (but, apparently, non-existent) contradiction in the palaeo-assemblage formed by the teeth in your hand