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Mike from North Queensland

Shark Tooth

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Mike from North Queensland

I found this tooth in the matrix I was cleaning up this morning but not being an expert on shark teeth I am unable to identify this one the closest match I can find is cretolamna appendiculata from the books I have but this appears to have the start of an extra cusp on one side of the tooth. The name comes from an article by N Kemp on Fossil Chondrichthyans

The specimen is from the toolebuc formation ( cretaceous albian )from Richmond western Queensland Australia and is 100 million years old give or take.

Thank in advance

Mike

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Edited by Mike from North Queensland

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Mike from North Queensland

Additional photos of tooth.

Is this just a variation ?

Mike

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post-4980-0-45590400-1414489596_thumb.jpg

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Doctor Mud

Can't help you with the ID, but that's a beauty of a tooth. I like the cusplets

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Troodon

My call is that you have a Cretolamna tooth and the cool cusplet is a pathology. Nice find. Be interested in what others have to say.

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jpwhite82

Looks like a Jackelotodus trigonalis, a species of mackerel shark. Cool find!

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sander

Looks like a Jackelotodus trigonalis, a species of mackerel shark. Cool find!

Jaekelotodus is not an albian genus, so i highly doubt that this sharkteeth is a Jaekelotodus. I think you have found a Dwardius siversoni, but wait until others agree with me before printing the label.

Greetings,

Sander

Edited by sander

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Xiphactinus

I'll throw in a Cretolamna vote

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siteseer

I agree. Sometimes, there is an extra cusplet in Cretalamna particularly from the Cretaceous. It could be a feature of its ancestor popping up occasionally across its long chronologic range.

My call is that you have a Cretolamna tooth and the cool cusplet is a pathology. Nice find. Be interested in what others have to say.

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sander

I still think you have a Dwardius, compare you tooth with the second example here:

http://users.skynet.be/somniosus/Albian_Dwardius.htm

it does not have the 5th cusplet, but other than that it is a match (in my eyes). the height of the root and the very slight dip in the middle of it are in both teeth the same.

By the way, you have a private message.

Greetings,

Sander

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Vball

My vote is also Dwardius siversoni Very Nice one!!!! Congrats

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Mike from North Queensland

Thanks all for the Id and yes I agree with Dwardius siversoni as the identification, however the western Australia formation they are from is about 2 million years younger than the formation these came from so unsure how long the species lasted. Attached is a side view of the tooth.

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Mike from North Queensland

As I looked at the half dozen Dwardius siversoni teeth I had there is one that is slightly different in that both cusplets slant about 10 degrees back from the face of the main tooth and there is a small hump at the bottom of the face on both sides of the tooth. Is this within the normal variation in the species as the tooth came from the same area, or is this a different species. I have drawn on one photo to show what I am referring to so I hope it helps.

Mike

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Edited by Mike from North Queensland

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Vball

Dwardius SIVERSON, 1999
Dwardius siversoni (ZHELEZKO, 2000) - Albian

Dwardius woodwardi (HERMAN, 1977) - Cenomanian

SIVERSON (1999) created a genus of uncertain familial affiliations, Dwardius, for Cenomanian teeth previously referred to as Cretolamna woodwardi HERMAN, 1977. This species was originally described by HERMAN (1977: 207-208) using an associated group of teeth recovered from the English Chalk and figured in WOODWARD (1911) as Lamna appendiculata. These teeth can not be included in the genus Cretalamna due to its very different root morphology (see SIVERSON, 1992: 530; 1996: 830). In Dwardius, anterior teeth have a more or less straight cusp, which, in contrast to Cardabiodon, are markedly enlarged relative to the mesially situated lateroposterior teeth.

It looks to me that the ID changes in the cenomanian to Dwardius woodwardi So yours is still Albian and would be D.siversoni if I'm reading this right.

Yes I think the cusp angle is well within the normal morphology. Mikael Silverson is a member of the forum and might provide more info if he sees this. He probably has documented your formation since he lives in Australia.

Mike

Edited by Vball

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sander

I'm with Vball on this one. Looks like a Dwardius siversoni.

Gr,

Sander

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