I’ve got a Weltonia Question

[Miocene_Mason]

So you see from Morocco (Ouled Abdoun, late paleocene- early Eocene?) These funky looking Cow sharks called Weltonia ancistrodon. Though I don’t own one, I still have questions about it. The questions I have are the following:

1) There are always lowers. Never, not once, have I seen for sale an upper. Where are they? What do they look like? What about Symphyseals?

2) Have they ever been found anywhere else? I find it hard to believe they only come from the one site. 

3) what is the purpose of the weird blade? Any papers on this?

[caldigger]

Excellent questions of which I have no answers to, but am eager to learn myself.

[Miocene_Mason]

Well, I answered the last question for myself, teeth of the genus Weltonia are found in Maryland (pamunkey group) and the London clay extremely rarely. The English one is Weltonia burmhamensis.

from Here and Here

Still no mention as to a reason or any other positions. Says that they lived in warm, shallow water so possibly that has something to do with that?

[Al Dente]

This web site (very good for Moroccan teeth) - http://users.telenet.be/sharkteethcollection/sharkteeth list totaal/sharkteeth list.htm

has this picture that includes an upper. 

[caldigger]

So is the little one the upper?

[Al Dente]

27 minutes ago, caldigger said:

So is the little one the upper?

Yes

[Troodon]

From Cappetta Chondrichthyes II book, (E,F) he also describes Heptranchias howellii (G) from the eocene of Morocco

 

 

From Arambourg paper 1952

 

 

 

 

 

 

[Miocene_Mason]

Thanks @Al Dente and @Troodon! That answers number one! This shark was full of hook teeth.

—————————————————

The two questions remaining are where are the other positions, and why did the sharks have such strange teeth? I would assume for the first of those that collecting bias is what means few get to the international marketplace, as well as their relative rarity.

The second, I still don’t have a definitive answer to, but we have a modern analog.

Heptranchias perlo or the sharpnose seven gill shark has the same tooth adaptation to a lesser extant. It’s diet depends on where it is, but it mostly focuses on teleost fish and soft-bodied cephalopods. Perhaps the teeth act like hooks. If this is the case, we wonder why it didn’t occur in all cow sharks. I would say that Weltonia type teeth are weaker and won’t work on larger fish. However, sometimes heptranchias eats crustaceans. I don’t thinks this would have been possible for Weltonia, as it’s primary blade is much longer and thinner. These are just my thoughts though, and not supported by much evidence. Still looking for papers on this.

[Troodon]

The tooth with the elongated acrocone is in a lateral position and not your primary tooth.  If you look at Arambourg dention the anterior lowers are more your traditional morphology.  Cappetta says that the general dental morphology is very close to Hexanchus apart from those teeth. 

[Miocene_Mason]

7 minutes ago, Troodon said:

The tooth with the elongated acrocone is in a lateral position and not your primary tooth.  If you look at Arambourg dention the anterior lowers are more your traditional morphology.  Cappetta says that the general dental morphology is very close to Hexanchus apart from those teeth. 

I didn’t notice that, if it was for catching fish, you would think it would be one the anterior teeth. Unless it would ambush them from the side.

[Troodon]

29 minutes ago, WhodamanHD said:

I didn’t notice that, if it was for catching fish, you would think it would be one the anterior teeth. Unless it would ambush them from the side.

Not really its the point you made by not being very strong, it just looks like a fish hook   Your typical morp anterior teeth are the best for catching prey.

[Troodon]

Let me add that these teeth are best found going through trays of small teeth from moroccan dealers at shows like Tucson.  

[siteseer]

One thing to think about is that the upper teeth are more delicate.  It's a similar situation with some fossil squalliform sharks: lowers are found more often because they are relatively more solid than the uppers.  As it is, squaliform lowers themselves tend to be rare because the root is not only rather thin but well-vascularized (full of tiny blood vessel passages).  They just don't survive too well as fossils.  It's why a complete/near complete tooth of something like Somniosus is such a collector's item.

 

It's also possible that Weltonia was a deepwater shark that rarely entered shallow coastal areas.

 

Jess

[siteseer]

On 6/29/2018 at 8:08 AM, Troodon said:

The tooth with the elongated acrocone is in a lateral position and not your primary tooth.  If you look at Arambourg dention the anterior lowers are more your traditional morphology.  Cappetta says that the general dental morphology is very close to Hexanchus apart from those teeth. 

 

Hi Troodon,

 

Arambourg illustrates the teeth with the higher acrocone as lateral teeth, but Cappetta in his 1987 Chondrichthyes II, noted it as an anterior.  The highest teeth in the mouth of sharks are the anteriors in nearly all (if not all) other sharks.  A tooth of this form would be good for snagging small fish, squid, and other soft-bodied prey.

 

I would assume Weltonia is also found in the Paleocene of more eastern parts of North Africa as well since the same phosphate deposits extend that way but those areas seem to be less-hunted for fossils (less talked about anyway these days anyway).  In the 80's there were collectors who had Early Eocene teeth from Tunisia and Late Cretaceous teeth from Egypt.

 

Weltonia was part of the great radiation of Paleocene sharks and rays that took place in the wake of the Latest Cretaceous mass extinction which had a significant effect on the diversity of sharks and rays worldwide.  The genus survived for a few million years but might have become too specialized and/or was uncommon in its day and therefore vulnerable to even a minor extinction event such as the one at the end of the Paleocene.  It lingered into the Early Eocene, but as noted above, it was quite rare.  The London Clay record is the only known Eocene one for the genus. 

 

Jess

[Troodon]

1 hour ago, siteseer said:

Arambourg illustrates the teeth with the higher acrocone as lateral teeth, but Cappetta in his 1987 Chondrichthyes II, noted it as an anterior.  The highest teeth in the mouth of sharks are the anteriors in nearly all (if not all) other sharks.  A

The illustration I show above is from Chondrichthyes II and  "F" is described as a lower anteriorlateral so its positioned about where Arambourg illustrated unless I'm not reading it or understanding it properly.

[siteseer]

1 hour ago, Troodon said:

The illustration I show above is from Chondrichthyes II and  "F" is described as a lower anteriorlateral so its positioned about where Arambourg illustrated unless I'm not reading it or understanding it properly.

 

I see I was looking at the note for the E figure but F is an anterolateral which can be the first tooth position distal to the symphyseal position.  For hexanchids Arambourg must've referred to all teeth distal to the symphyseal as laterals.  I guess I never picked up on that before.