Method to determine shark development stage from teeth

[David in Japan]

To all the shark expert of the forum.

 

Is there any method or features to look for in order to determine if a shark tooth comes from a juvenile or an adult.

 

I know that in a species well documented or largely collected, it can be easily determined by the size of the tooth.  However in the case of a not well- documented or isolated tooth, is there a feature that could hint for the development stage of the specimen?

 

Thank you, 

 

David

[Miocene_Mason]

Relevant link

 

I am no expert, but I have yet to hear way to tell whether or not a singular tooth is at a certain stage of development. A larger sample size is necessary.

[David in Japan]

11 hours ago, WhodamanHD said:

Relevant link

 

I am no expert, but I have yet to hear way to tell whether or not a singular tooth is at a certain stage of development. A larger sample size is necessary.

Wow thanks for the link Mason. I agree that nothing can be done without a large sampling but i was naively hoping that some feature could be only found on young shark's tooth.

[Miocene_Mason]

9 minutes ago, David in Japan said:

Wow thanks for the link Mason. I agree that nothing can be done without a large sampling but i was naively hoping that some feature could be only found on young shark's tooth.

Unfortunately, evolution was not so kind. Certain species have some features better expressed in juveniles, or the other way around. Is there a particular species you have in mind?

[David in Japan]

10 minutes ago, WhodamanHD said:

Unfortunately, evolution was not so kind. Certain species have some features better expressed in juveniles, or the other way around. Is there a particular species you have in mind?

 I found a 3 mm (from base of the root to apex) odontaspid tooth. Odontaspis sp. is mentionned in a lot of document and not rare at all but no full description of the tooth nor photo. Show the tooth to colleagues from other museums. They just told me "oh, you found an odontaspis tooth. You have good eyes."

[Miocene_Mason]

16 minutes ago, David in Japan said:

You have good eyes."

No kidding, 3MM! Unless it’s a posterior, which should be rather distinctive, it is almost certainly a juvenile or neonate.

[David in Japan]

1 hour ago, WhodamanHD said:

No kidding, 3MM! Unless it’s a posterior, which should be rather distinctive, it is almost certainly a juvenile or neonate.

I think that juvenile or very young shark is the more logical explanation due to the size but curiosity won and i had to look for further information.

[siteseer]

On 11/17/2019 at 4:35 AM, David in Japan said:

To all the shark expert of the forum.

 

Is there any method or features to look for in order to determine if a shark tooth comes from a juvenile or an adult.

 

I know that in a species well documented or largely collected, it can be easily determined by the size of the tooth.  However in the case of a not well- documented or isolated tooth, is there a feature that could hint for the development stage of the specimen?

 

Thank you, 

 

David

 

Hi David,

 

Is it a fossil tooth?  If it's from the Cretaceous-Eocene, there were several smaller species.  Consider also that teeth on the intermediate bar and the posterior teeth are much smaller than the other teeth.  The posterior teeth change shape as well as get smaller as they go toward the back of the mouth.  The last couple of teeth don't have much of a cusp - more like a crushing tooth.

 

Do you have a photo of the tooth?  Some cat shark teeth resemble sand tiger teeth.

 

You should do a search for Odontaspis and Carcharias on the forum.  You'll probably see more discussion on various sand tiger tooth forms.

 

Yeah, it isn't always clear if you have a juvenile or adult tooth when the tooth is small especially as you go back through time.  However,  the anterior teeth of Heterodontus juveniles have distinct lateral cusplets which do get smaller as the shark gets older so there is an indicator with that genus.

 

Jess.

 

 

 

 

 

[David in Japan]

On 2019/11/19 at 6:30 AM, siteseer said:

 

Hi David,

 

Is it a fossil tooth?  If it's from the Cretaceous-Eocene, there were several smaller species.  Consider also that teeth on the intermediate bar and the posterior teeth are much smaller than the other teeth.  The posterior teeth change shape as well as get smaller as they go toward the back of the mouth.  The last couple of teeth don't have much of a cusp - more like a crushing tooth.

 

Do you have a photo of the tooth?  Some cat shark teeth resemble sand tiger teeth.

 

You should do a search for Odontaspis and Carcharias on the forum.  You'll probably see more discussion on various sand tiger tooth forms.

 

Yeah, it isn't always clear if you have a juvenile or adult tooth when the tooth is small especially as you go back through time.  However,  the anterior teeth of Heterodontus juveniles have distinct lateral cusplets which do get smaller as the shark gets older so there is an indicator with that genus.

 

Jess.

 

 

 

 

 

Hi Jess,

It is indeed a late cretaceous (santonian) tooth. Fully constituted anterior tooth (crown, root and cusps).

I do not have access to my microscope, i will post a photo later.

[David in Japan]

On 2019/11/19 at 6:30 AM, siteseer said:

 

Hi David,

 

Is it a fossil tooth?  If it's from the Cretaceous-Eocene, there were several smaller species.  Consider also that teeth on the intermediate bar and the posterior teeth are much smaller than the other teeth.  The posterior teeth change shape as well as get smaller as they go toward the back of the mouth.  The last couple of teeth don't have much of a cusp - more like a crushing tooth.

 

Do you have a photo of the tooth?  Some cat shark teeth resemble sand tiger teeth.

 

You should do a search for Odontaspis and Carcharias on the forum.  You'll probably see more discussion on various sand tiger tooth forms.

 

Yeah, it isn't always clear if you have a juvenile or adult tooth when the tooth is small especially as you go back through time.  However,  the anterior teeth of Heterodontus juveniles have distinct lateral cusplets which do get smaller as the shark gets older so there is an indicator with that genus.

 

Jess.

 

 

 

 

 

Here is a picture of the tooth. Because of the matrix colour the root is hard to see however the root is fully formed.

[siteseer]

I'm just looking at this now.  There is at least one very small sand tiger tooth form from the Cenomanian of Texas (see Welton and Farish, 1993, page 91) their "The Collector's Guide to Fossil Sharks and Rays from the Cretaceous of Texas").  Your tooth would be in that size range.

 

Jess

[David in Japan]

On 2020/1/4 at 7:13 AM, siteseer said:

I'm just looking at this now.  There is at least one very small sand tiger tooth form from the Cenomanian of Texas (see Welton and Farish, 1993, page 91) their "The Collector's Guide to Fossil Sharks and Rays from the Cretaceous of Texas").  Your tooth would be in that size range.

 

Jess

 

Thank you, I will have a look.

 

I visited last week Pr. Kitamura who is the specialized in Shark tooth fossils from this formation. I met him to consult him on a different subject but bright him the fossil anyway. He confirmed me it was an Odontaspididae shark tooth. Some Odontaspididae tooth fragments has been found in the lower formation, but none has been found in the middle formation yet where I found it. He also told me that the only way to find if it is a juvenile tooth or an adult one was to find a lot of tooth ( as I expected).

It is however the smallest shark tooth he has ever seen from this formation, it is even smaller than juvenile Cretalamna' s teeth that were found in a part of the formation which is considered to be an ancient shark nursery.