Just a nice santonian fish tooth I found in Japan

[David in Japan]

Hi TFF friends, 

 

Just to show you my latest find.

 

Himenoura lower formation 

Late cretaceous, santonian

Amakusa, japan

Height: 9mm

 

I think it might be an Enchodus tooth.

There are occurrences of Enchodus sp. from the scientific litterature and saw some of the fossils, however as those teeth are poorly preserved, I am not sure at 100%.

 

It has one notch like structure at the apex, one carina on the proximal edge with very well preserved serrations from the apex to the base of the tooth.

The distal edge is round. Fine striations are running all over the crown from the base to the apex.

 

 

 

 

 

[Fossildude19]

Looks a bit more like some sort of spine, to me.

 

[Brevicollis]

Nice tooth ! What fish are known from this formation ? Because your tooth reminds me more of a sawfish tooth than Enchodus. But i am not an expert, so better ask them. I dont exactly know who the fish experts in this Forum are, but @Fin Lover and @Al Dente could maybe say more about it.

Here two pictures of my Onchopristis tooth. Migth look similar.

Edited March 13 by Brevicolis

[Fin Lover]

@Brevicolis, I appreciate the vote of confidence, but I am definitely not an expert. 

[Fossildude19]

1 minute ago, Fin Lover said:

@Brevicolis, I appreciate the vote of confidence, but I am definitely not an expert. 

 

But you ARE quite knowledgeable. 

[rocket]

@Brevicolis: nice idea, but Onchopristis never has serration

 

@David in Japan: very cool find! how is the cross-section? Looks like a fragmented tooth for me

[Brevicollis]

26 minutes ago, rocket said:

nice idea, but Onchopristis never has serration

I know, but @David in Japan's tooth looks based in the form and the little hook kinda like one. Also, there have been plenty of prehistoric (Saw)fish that i dont know the name of, we'll probably find one, that matches whith this tooth.

[Anomotodon]

This isn’t a sawfish or shark, because there is no enameloid. I think this is a lizardfish tooth, Cimolichthys, they always have the “hook” at the apex. Although a weird Enchodus is a possibility too. I’ve never seen either genus with such visible serrations, that’s very interesting! 
 

Partial cephalic clasper (a head spine) of a hybodont shark is another possibility, but this seems more like a fish tooth to me, especially since claspers in the Late Cretaceous tend to not have “hooks”.

 

Edited March 13 by Anomotodon

[rocket]

 

59 minutes ago, Anomotodon said:

This isn’t a sawfish or shark, because there is no enameloid. I think this is a lizardfish tooth, Cimolichthys, they always have the “hook” at the apex. Although a weird Enchodus is a possibility too. I’ve never seen either genus with such visible serrations, that’s very interesting! 
 

Partial cephalic clasper (a head spine) of a hybodont shark is another possibility, but this seems more like a fish tooth to me, especially since claspers in the Late Cretaceous tend to not have “hooks”.

 

not a bad idea, but, the serration kills it 

 

But I would not agree with Cimolichthyes, I am sure the tooth from @David in Japan has a clear serration and neither Onchopristis nor Cimolichthyes have

 

(e.g. I know the paper where the pics comes from, @Anomotodon, INagrodski, Shimada & Schumacher, great work!

Edited March 13 by rocket

[rocket]

4 hours ago, David in Japan said:

Hi TFF friends, 

 

Just to show you my latest find.

 

Himenoura lower formation 

Late cretaceous, santonian

Amakusa, japan

Height: 9mm

 

It has one notch like structure at the apex, one carina on the proximal edge with very well preserved serrations from the apex to the base of the tooth.

The distal edge is round. Fine striations are running all over the crown from the base to the apex.

 

is the distal end really round or more oval?

I would more assume it is a bony serrated sting from a fish, when it is round at the distal end

some have "hooks"

Edited March 13 by rocket

[hemipristis]

Cutlassfish?

 

 

[deltav2]

27 minutes ago, hemipristis said:

Cutlassfish?

 

 

They lack serrations 

[David in Japan]

The serrations are quite mysterious. I thought it could be some sort of Enchodus gladiolus at first.

 

The base of the tooth is not round, but more oval.

 

This formation is known for its shark tooth but not for the fishes. Finds are fragmentary, sometime you can find some vertebrae but always isolated finds. Except the Amakusaichtys, no fish has been described here and there is only a mention about Enchodus tooth but no description of the tooth at all.

 

[David in Japan]

My first thought was alepisauriform 

[FossilDAWG]

I'm inclined to agree with Tim who suggested fin spine.  It looks like there are remnants of the rays on the side opposite the "serrations".

 

Don

[Anomotodon]

Trichiurids (cutlassfish) and alepisauriforms (lancetfish) both have hooked apices, but I believe their teeth typically have the “hook” formed by the acrodin cap - thick enamel-like layer on the tooth apex. Acrodin caps tend to preserve well - I don’t see any evidence of it present. Also, trichiurids originated in the Cenozoic. 
 

Cimolichthys and Enchodus (and hybodont cephalic claspers of course) typically do not have an acrodin cap, which is why I think they are more likely candidates.

 

As for serrations, they tend to emerge independently all the time in random vertebrate groups, so I have some suspicions about their diagnostic value (at least past family level). Here is an example of a serrated actinopterygian tooth: a serrated Xiphactinus from Albian of Texas. I wouldn’t be surprised if someone here saw a serrated Enchodus tooth.

 

edit: here is a serrated Enchodus 

Edited March 14 by Anomotodon

[David in Japan]

On 3/14/2024 at 10:16 AM, FossilDAWG said:

I'm inclined to agree with Tim who suggested fin spine.  It looks like there are remnants of the rays on the side opposite the "serrations".

 

Don

 

Hi, Don.

I am a little bit confused but what are the rays you are mentioning? I can't find anything like that on the tooth. I searched for fossil fin spines on master Google to but I don't understand what you are referring too.

 

On 3/14/2024 at 10:36 AM, Anomotodon said:

Trichiurids (cutlassfish) and alepisauriforms (lancetfish) both have hooked apices, but I believe their teeth typically have the “hook” formed by the acrodin cap - thick enamel-like layer on the tooth apex. Acrodin caps tend to preserve well - I don’t see any evidence of it present. Also, trichiurids originated in the Cenozoic. 
 

Cimolichthys and Enchodus (and hybodont cephalic claspers of course) typically do not have an acrodin cap, which is why I think they are more likely candidates.

 

As for serrations, they tend to emerge independently all the time in random vertebrate groups, so I have some suspicions about their diagnostic value (at least past family level). Here is an example of a serrated actinopterygian tooth: a serrated Xiphactinus from Albian of Texas. I wouldn’t be surprised if someone here saw a serrated Enchodus tooth.

 

edit: here is a serrated Enchodus 

 

No acrodine cap on this fossil. The hook doesn't show any sigh of it. 

 

Some hybodont teeth were find in this formation, I presume cephalic clasper is a nice to explore. 

[FossilDAWG]

I was referring to the linear features (indicated by arrows) that look like they are continuing on to the matrix from the tooth.

 

Don