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Shark Tooth Reunion - 27 Million Years Later


Doctor Mud

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Hi everyone,

Here's a large Mako with an interesting story.

I've heard of meg divers finding separate pieces of the same tooth - even in different dives.....similar idea here but from a cliff!

This tooth comes from an outcrop of Concord Greensand, Late Oligocene (27 million yrs old) in the South Island of New Zealand.

We "mined" the thin phosphatic horizon (about 2 cm thick) in the cliff face within the greensand and it contained sharks teeth, penguin and cetacean remains. Most remains were fragmentary and a bit beat up - probably as a result of erosion since this is what is called an unconformity. There is a time gap of about 4 - 6 million years missing below the greensand where there was net zero deposition.

I guess this might be a similar situation to the erosion of megs from Miocene deposits on the ocean floor?

Anyhow, this tooth was found in 3 separate pieces over the period of several days work. They came from around the same area in the cliff but I had so many teeth that it was not obvious that they went together. I realized the top two fit together first.

I had lamented for a while that the basal bit must have come from a mighty tooth and wished that I had found the rest.

Then one day I was looking at it and figured out that the three bits went together. Apart from an angustidens (my only complete one out of 100s of teeth) this turned out to be the largest tooth from this locality. It's about 2 inches long (on the slant) in it's current state......

post-11936-0-16774000-1398057779_thumb.jpg

Edited by Doctor Mud
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In it's current state..........

Oh no - I think I know where he is going with this :D

How big would this tooth have been if it was complete? Root and all?

First I will need to identify it and then I was hoping to use the fossil sets from Elasmo.com to produce a scaled image of the tooth.

I might even have a go at reconstructing the root....

First some shots from different angles:

post-11936-0-55269300-1398058087_thumb.jpg

I was thinking Isurus/Cosmopolitodus spp.

Possible candidates are I./C. hastalis or I/C. retroflexus? What do you guys think?

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Here's an example of what I want to do:

Perhaps it's Cosmopolitodus hastalis?

Looks a bit like the second lower anterior

post-11936-0-63169900-1398058388_thumb.jpg

Overlaying my tooth on this image (just by sitting the tooth on top of my Iphone!) I get this:

post-11936-0-22026100-1398058348_thumb.jpg

Scale bar = 2 inches.

This would be the maximum possible reconstructed size (getting up toward the magic 3 inch slant size) since these lower anteriors have large root lobes. At least greater then 2.5 inches anyway.

If it is actually an upper anterior:

post-11936-0-93861700-1398058784_thumb.jpg

The root lobes are shorter so the reconstructed slant length would be shorter.

Any help or suggestions from the experts would be greatly appreciated!

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no help - just jealousness! Very nice finds - a 2cm thick layer? Amazing!

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no help - just jealousness! Very nice finds - a 2cm thick layer? Amazing!

The 2 cm thick layer did have abundant teeth and bones but was mostly phosphate nodules - still you could find something in every chunk you took out.

Sawshark rostral spines were the most common teeth funnily enough followed by Mako teeth.

You used to be able to access the layer in an old marl quarry, but the quarry was purchased by a demolition company and they filled it in with rubble :(

If you look on a geological map though there are other exposures around and this tooth was from one of those. We started working this site since the quarry was changing hands so quickly and getting access became a problem.

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I suggest you get back out there and find the rest of it :P Seriously, nice tooth.

LOL! I unfortunately realised the connection a while after working this site. I haven't been back in over 20 years and I hope it is still there. The area near this site has been changing so quickly over the years since it is in an industrial area. We used to work the greensand in a quarry, but later found an excellent exposure in a nearby creek. Who knows maybe the rest of this tooth is still there waiting to be found? I'm in Australia now but often dream of returning to this site. For some reason I drifted away from fossil hunting and it was recently - thanks to a fossil whale vertebrae picked up on a beach - that I caught the bug again.

This is where my passion for fossil hunting began. A friend and I used to catch the bus to near this quarry when I was 11-16 years old and spend the whole day there on our knees working the greensand. We got some interesting finds over the years and learnt a lot about fossils. Thanks to Ewan Fordyce from the University of Otago. We used to take our finds in and he would take the time to help identify them.

My buddy seemed to have a knack for finding whale ear bones, I think he even found a skull fragment. I believe casts were made for the university collection.

We found one almost complete angustidens each in all the years we worked this place.

Now I'm back into fossils I've been going through my old collection and this tooth came up. Its a beautiful tooth - has an air of mystery and intrigue and also reminds me of the "good old days" when I used to get lost for days at a cliff face.

Edited by Doctor Mud
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I have rocks that transport me back almost 40 years and millions of years at the same time too. Interesting phenomenon.

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That's unheard of! And the size is amazing! Congrats on "those/that" find/s. Lol

Sorry i can't help with an ID.

~Charlie~

"There are those that look at things the way they are, and ask why.....i dream of things that never were, and ask why not?" ~RFK
->Get your Mosasaur print
->How to spot a fake Trilobite
->How to identify a CONCRETION from a DINOSAUR EGG

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You might also consider Isurus oxyrinchus as a possible candidate.

Daryl.

Thanks Daryl,

I didn't realise that the fossil record for I oxyrinchus extended back to the Oligocene but now I see that it does.

I'll add this species as a possible candidate - thanks !

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I'm new to sharks teeth collecting - so I guess you could call my eye untrained.....

But I did notice the curvature on this tooth is more like Isurus oxyrinchus than tooth positions from the other Isurus species. It curves lingually then recurves labially. (left then right in the image).

To me this looks more like I. oxyrinchus than other Isurus species. The curvature isn't as strong as modern I. oxyrinchus but I guess this is an early form. Looking at some teeth identified as I. oxyrinchus from the early Miocene from Belgium the curvature is more like my specimen.

See comparison of different teeth from different Isurus species. I only included examples of teeth that re-curve or curve labially (to the right).

Images derived from Elasmo.com

post-11936-0-25296000-1398397893_thumb.jpg

Edited by Doctor Mud
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