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Show me your six and seven gill shark teeth


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The mass extinction event at the end of the Cretaceous was devastating to sharks and rays.  Ptychodus and Cretxyrhina had died out several million years before that but other successful genera like Squalicorax, Scapanorhynchus, and the sclerorhynchid sawfishes disappear from the fossil record at the end.  Among hexanchids the genera Hexanchus, Gladioserratus, Heptranchias, and Notidanodon survived.  Whatever killed off other sharks, whether the direct or indirect effects of an asteroid impact or the sharp drop in sea level at the time, apparently did little to disturb deepwater environments.  Climates continued to be warm across the Paleocene but there was an odd extinction event at the end which did affect hexanchids.  It has been proposed that there was a large-scale release of methane in sea beds which was likely lethal to deepwater animals.  Notidanodon and Gladioserratus disappeared but Hexanchus and Heptranchias survived perhaps because they ventured into shallower water more often than the other two genera.

 

When we look at the wealth of Paleocene shark teeth from Morocco available at fossil shows, we get an idea of what the common sharks were in that part of the world which gives us a point of comparison for sites elsewhere (Maryland/Virginia, South Carolina, Cannonball Sea sites, Herne Bay, the Paris Basin, Denmark, New Zealand, etc.).  I'm not saying that gives a highly accurate view of diversity but Moroccan dealers bring everything they find so it's at least an indicator that can be professionally studied at some point in the future.  Hexanchus was rather common while Notidanodon was uncommon.  Heptranchias is quite rare.  I don't think I've seen any Paleocene Gladioserratus teeth from Morocco.  It might have been rare or absent there because the Tethys Sea wasn't to its liking for some reason (not deep enough?).

 

I've seen some nice representatives of Paleocene hexanchids on these pages.  Here's a Notidanodon upper lateral from the late Paleocene of Morocco to add to the group.

 

 

notidan_mar_up.jpg

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fossilsonwheels

Our latest Cow Shark tooth and it is pretty cool. This is an upper Heptranchias from the Oligocene of Poland.

heptranchias3.jpg

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Notorynchus primigenius (Agassiz, 1835)

Canal Albert, Gellik, Belgium

Kerniel Sands, Rupelian, Oligocene

Notorynchus primigenius.jpg

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fossilsonwheels
18 hours ago, Chimera said:

Notorynchus primigenius (Agassiz, 1835)

Canal Albert, Gellik, Belgium

Kerniel Sands, Rupelian, Oligocene

Notorynchus primigenius.jpg

Gorgeous tooth and great location ! Thank you for sharing. 

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fossilsonwheels

Not the best tooth but a great location.  

 

Notidanodon loozi

Paleocene

Woolwich Bottom Bed

Herne Bay 

Kent UK 

099B17F7-90DE-419F-8CC7-2433F34C551E.jpeg

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Pathological Hexanchus andersoni 

Middle Miocene 
Temblor Formation 

Round Mountain Silt Member

Bakersfield, California 

USA

C4022ABD-ACBB-4BC3-9709-703E73AE87AF.jpeg

0C81D6DD-A4B1-4044-8EC3-97D3B8CE9391.jpeg

524CEC6D-0A1E-4AAC-8C4D-70D635196BA0.jpeg

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That's a funky tooth and in great condition.

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One interesting interval of geologic time is the Eocene Epoch.  Worldwide climates had been warm-tropical as a trend across the Mesozoic Era with an interruption at the end before resuming in the Paleocene and Early Eocene.  Climates began cooling in the middle Eocene to the point that ice began building at the poles by the early Oligocene - something that hadn't happened since perhaps the early Permian.  This reversal of the climatic trend would lead to further glaciation at the poles and major glacial advances during the Pleistocene.

 

The sevengill shark, Notorynchus, appears in the early Eocene and is perhaps best known from that time from the London Clay of various sites in the U.K.  Paleontologists once considered the genus as present in the early Cretaceous but all Mesozoic and Paleocene species have been reassigned to the genus Gladioserratus.  It seems Notorynchus descended from Gladioserratus with the latter disappearing by the early Eocene.  Today, Notorynchus frequents temperate waters.  It's possible it evolved as a form that tolerated and later preferred cooler water.

 

This Notorynchus upper tooth comes from the middle Eocene Castle Hayne Formation in Onslow County, North Carolina.  I don't have more exact information than that but believe it was collected in a limestone quarry, a locality where collectors are allowed to visit periodically to collect fossils.  The tooth measures just under 5/8 inches (15mm) wide.  It was identified as N. kempi, a species known from the middle-late Eocene of Europe and central Asia.

 

Jess

7gill_nc.jpg

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will stevenson

I have this sweet gladioserratus from the Uk, not a common piece!

41B02832-7C13-4AEC-BDD9-3A1C10960E23.jpeg

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hokietech96
3 hours ago, will stevenson said:

I have this sweet gladioserratus from the Uk, not a common piece!

 

That is a great looking tooth!

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will stevenson
1 hour ago, hokietech96 said:

That is a great looking tooth!

Thanks, it’s from the senonian chalk

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11 hours ago, will stevenson said:

Thanks, it’s from the senonian chalk

 

Wow, Will that is a great tooth.  Is that from Devon?

 

Jess

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will stevenson
3 hours ago, siteseer said:

 

Wow, Will that is a great tooth.  Is that from Devon?

 

Jess

Thanks:P it’s from a location that I haven’t heard of which makes sense as it’s  from an old collection

4C940E16-F7F7-4683-9898-1323766282E5.jpeg

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41B02832-7C13-4AEC-BDD9-3A1C10960E23.jpeg

Great teeth, I' am not convinced that is a tooth of gladioserratus, but something more interesting, probably a Galeocorax jaekeli.

The labial view is required.

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will stevenson
26 minutes ago, Chimera said:

 

Great teeth, I' am not convinced that is a tooth of gladioserratus, but something more interesting, probably a Galeocorax jaekeli.

The labial view is required.

Thanks;) is this good enough?

 

746C24D5-36B4-4AC2-92DA-4C235C3E3765.jpeg

AEE0B376-2603-434C-978A-D32ADFD7B1E0.jpeg

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Yes, it enought to be quite sure that this teeth is related to Galeocorax. To compared with Galeocorax jaekeli from Northfleet, Kent (drawn from Cappetta, 2012)

image.png.b22b6a9f1f9524695d76bd460fde3534.png

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will stevenson
15 minutes ago, Chimera said:

Yes, it enought to be quite sure that this teeth is related to Galeocorax. To compared with Galeocorax jaekeli from Northfleet, Kent (drawn from Cappetta, 2012)

image.png.b22b6a9f1f9524695d76bd460fde3534.png

Thanks, must be quite rare if the one chosen for a Drawing is incomplete!

thanks once again for helping me^_^

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Yes a rare species, found also in France, Netherlands; Lithuania and Russia.

Always a great pleasure:thumbsu:

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The Oligocene was the time when a major ice sheet developed on Antarctica nearly covering it by the early part of the epoch.  There had been the start of a cooling trend in world climates in the middle Eocene but much of Antarctica was still densely-forested into the late Eocene as it had been during the Mesozoic.  The ice sheet retreated and then advanced again during the Oligocene.  Much of this appears to have been caused by changes in ocean currents in response to the changing positions of the continents which had been separating since the late Triassic.  A cold water current from deepwater began circling Antarctica in the early Oligocene.  Antarctica had separated from South America in the late Cretaceous (its last contact with another of the Gondwanan continents) but the cold water current didn't develop until the early Oligocene.  The result was that Antarctica froze over which also had a chilling effect elsewhere on the planet, dropping sea levels as water got locked up in the ice.  Because the Oligocene is only about ten million years long and covers a time of lowered sea levels, shallow marine deposits of that age are fewer and less extensive.  That's why it's not always easy to get a sample of Oligocene shark teeth.  There are sites in the Carolinas, Florida, northern California, Oregon,  British Columbia, Germany, and Kazakhstan but the only area that seems to produce with any regularity are sites in South Carolina.  There was a time maybe 10-20 years ago when land sites produced less due to a drought in the area.

 

Here is a Notorynchus tooth (just over 5/8 inches, or 17mm, across) from the early Oligocene Ashley Formation found in a creek off the Edisto River, South Carolina.  Also show is a Notorynchus symphyseal tooth (3/8 inches, or 1cm, across) from the early Oligocene River Bend Formation, a site around New Bern, North Carolina.  I'm not sure people still collect there.

notor_oligsc.jpg

notor_cstle.jpg

notor_cstle2.jpg

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Here are an upper and lower anterolateral of Notorynchus from the early Oligocene of Weinheim/Neumuhle, Alzey, Germany.  

noto_brd.jpg

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will stevenson

Nice notorynchus  kempi from khazakstan and a notidanodon loozi from morocco

F34CD039-EC9F-4B81-A3A9-85C745E4DD21.jpeg

DC75770B-7194-48BA-83FA-5C53465C2795.jpeg

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siteseer

Nice teeth, Will!

 

Jess

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siteseer

Another Oligocene sevengill shark...this one is from the late Oligocene Chandler Bridge Formation, Summerville, South Carolina.  It's right about an inch (2.5cm) wide.  It was collected in the late 80's-early 90's at a time when local collectors were finding a lot of stuff.  The pickings would get slim within the next few years due to a drought that lasted several years.  This was the best cow shark tooth I could get from the formation - tough to get a complete one.  I was looking for teeth from oddball localities and samples of faunas back then. 

 

noto_chbr.jpg

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