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FossilDAWG

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A couple of weeks ago I stopped by Blue Banks, just north of Purse State Park MD.  The Paleocene Aquia Formation is exposed there, and teeth and bones of a variety of species erode from the exposures and accumulate in gravel along the shore.  Unfortunately the Potomac River was in flood stage, so the gravel along the shore was submerged despite the low tide.  A driving rain storm did not help matters.  I scooped gravel and passed it through a couple of screens, and recovered a handful of the usual small sand tigers and ray teeth, before calling it quits after an hour or so.  The following was the largest tooth I collected by some margin.  I don't see anything like it on Elasmo.com.  There are no serrations and no cusps.  Any suggestions for an ID would be most welcome.

 

Don

 

 

purse tooth 2.jpg

purse tooth 3.jpg

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Looks much like a Carcharodon hastalis to Me, but I do not know the age of that formation.

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Hi Don and Tony,

 

Yeah, I'm thinking it's a much younger tooth, C. hastalis as Tony noted, that got washed into the gravel from somewhere else.  I think I've heard of people finding Miocene teeth on the Potomac.

 

Jess

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I've seen site contamination at this location before. 

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38 minutes ago, Gizmo said:

I've seen site contamination at this location before. 

What is the chance that there is a pocket of Miocene nearby, contributing to the mix?
I know that the general dip/strike suggests that to be unlikely, but...

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29 minutes ago, Auspex said:

What is the chance that there is a pocket of Miocene nearby, contributing to the mix?
I know that the general dip/strike suggests that to be unlikely, but...

A possibility, also native american middens nearby. It's a heavily collected site with many people coming over from Calvert Cliffs carrying Miocene fossils.

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33 minutes ago, Auspex said:

What is the chance that there is a pocket of Miocene nearby, contributing to the mix?
I know that the general dip/strike suggests that to be unlikely, but...

 

4 minutes ago, Gizmo said:

A possibility, also native american middens nearby.

Or it could have been dropped by a collector (intentionally or accidentally).

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The most common scenario is a parent bringing teeth to insure a successful hunt for a child.

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22 minutes ago, Gizmo said:

The most common scenario is a parent bringing teeth to insure a successful hunt for a child.

Which muddies the water for serious collectors.

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I’ve found a Miocene lemon tooth here. Must be seeders.

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My first impression was also that it has a mako-ish aspect.  Certainly there is always the possibility of contamination from someone dumping out a collecting bag or some other shenanigans.  "Salting" for kids is also always an unpleasant possibility, but this tooth is not all that large (note scale is in cm not inches) or impressive, certainly not more so than many of the Striatolamia that are common at the site.  I was wondering if anything along the lines of Macrorhizodus praecursor/M. americana (which I have collected from Eocene outcrops in Georgia) occurs in the Paleocene, or in the Lower Eocene Nanjemoy Formation which is present nearby.  Also Elasmo.com mentions that Isurolamia lower anteriors lack cusps, but this tooth position is apparently not illustrated.  Just wondering when the transition from Cretalamna to uncusped Mako-type teeth occurred.

 

Don

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37 minutes ago, Gizmo said:

The most common scenario is a parent bringing teeth to insure a successful hunt for a child.

I was hoping that this was not that widespread...

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5 minutes ago, FossilDAWG said:

Macrorhizodus praecursor

Very rarely present according to some sources I believe, but this has too much “shoulder” in my opinion. It’s also not the type of preservation you’d expect from Purse but very typical of Miocene sites.

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There is Xiphodolamia ensis, but the root is wrong.

  • I found this Informative 1
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@MarcoSr

Any ideas on this?

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5 minutes ago, Auspex said:

There is Xiphodolamia ensis, but the root is wrong.

Blade isn’t “bendy” enough either.

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10 minutes ago, WhodamanHD said:

Very rarely present according to some sources I believe, but this has too much “shoulder” in my opinion. It’s also not the type of preservation you’d expect from Purse but very typical of Miocene sites.

I agree it's not a M. praecursor/americanus, I'm just wondering what came between the cusped Cretalamna lineage and the uncusped mako line, and when that happened.

 

The color balance is a little off in the photos. The preservation, to me, seems to be not different than several of the teeth I have from Purse.  Of course, I can also point to teeth from Brownies that seem to have similar preservation as well.

 

Don

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22 minutes ago, WhodamanHD said:

Blade isn’t “bendy” enough either.

That could vary greatly by tooth position, but yeah, it's clearly not X. ensis just by the root.

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1 hour ago, Auspex said:

I was hoping that this was not that widespread...

Not a rare occurrence here by any means. Reported and documented at Monument Rocks in Kansas were handfuls of small Miocene teeth were scattered causing much confusion.

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4 minutes ago, Gizmo said:

Not a rare occurrence here by any means. Reported and documented at Monument Rocks in Kansas were handfuls of small Miocene teeth were scattered causing much confusion.

I remember a thread here about a hemi found in Arkona, Canada. 

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9 hours ago, ynot said:

@MarcoSr

Any ideas on this?

 

Blue Banks is zone 2 of the Piscataway member of the Palaeocene Aquia Formation.  The Miocene exposures are far downriver from this site.  The Eocene Nanjemoy Formation exposures are downriver of this site.  Miocene hastalis teeth are not washing upriver.  On very rare occasions Cretaceous teeth wash downriver to this site but they are black and reworked so I don't think the tooth could be a Cretoxyrhina mantelli.  In forty five years collecting the Aquia I've never seen a tooth that looks like this tooth from that formation.  To me it is 100% a contaminant.

 

Marco Sr.

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Thanks Marco Sr, Gizmo, Whodaman, ynot, and Auspex.  A contaminant it is.

 

Don

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