Squalicorax review

[siteseer]

Here are a couple of specimens I received many years ago (mid-90's?) from a certain collector in Ohio who has since moved to the tropics.  Both are also from a quarry in/around Big Stone City, Grant County, South Dakota.  The larger one on the left is just under 9mm along the mesial edge; the other one looks right at 8mm.  These were photographed separately because they show a little pyritization on them though it doesn't show well in the photo.

Edited May 24, 2022 by siteseer

[siteseer]

Here are two teeth from Ekalaka, Carter County, Montana.  The collector didn't know the formation but based on what he found, he thought it was the equivalent of the Carlile Shale.  The larger tooth  is 16mm along the mesial edge; the smaller one is just over 13mm.

[siteseer]

Here are two teeth from the Turner member of the Carlile Formation - a site at Osage, Weston County, Wyoming.  The larger tooth is 17mm along the mesial edge.  The smaller tooth is 13mm - might have been 14 before the tip was worn a bit.  I think I got these two in a trade with a psychologist who collected fossils.  I was out there in the mid-90's with a friend who was a geologist.  We found a spot where the Turner was exposed but didn't find any teeth.  

[ThePhysicist]

Turonian crows from North Texas (probably S. falcatus). 

 

[siteseer]

That's a nice-looking group.  I don't have any Squalicorax from that site so it's a great addition to the thread.  Thanks.

[siteseer]

Here's one from Bettrechies, France.  It measures about 9mm along the mesial edge.  S. falcatus.

Edited May 29, 2022 by siteseer

[siteseer]

Here are some teeth from the Carlile Shale, Fairport Shale Member and from a site southwest of Beloit, Mitchell County, Kansas.  The largest tooth is the second one from the left.  It measures about 14mm along the mesial edge from crown tip to root lobe end.

[siteseer]

We've left the Turonian and are moving on to the Coniacian.  It's a short interval of geologic time accounting for about 3 million years.  The transition zone between the Eagle Ford Group and the Austin Chalk has been said to be Coniacian-age.  I have just these few teeth from a site in Dallas County, Texas.  The tall anterior on the right is the largest tooth at about 10mm along the total mesial edge including the root.  I don't know if the small size of the teeth is representative of Squalicorax at the time but I doubt it.  It's possible the site was popular with juveniles.

 

As a side note, I had assumed the other tooth was a sand tiger but it lacks a nutrient groove and bears folds on the crown.  It might be an Anomotodon tooth.

 

 

[siteseer]

Here is a group of Squalicorax falcatus teeth from the Smoky Hill Chalk which represents the Late Coniacian to Early Campanian with much of it being Santonian age (roughly 84-87 million years ago).  I think it's a good group with which to transition from the Coniacian to the Santonian.  The largest tooth is about 26 mm along the mesial edge.  It appears that the species reaches its largest size during the Santonian but you still see some smaller teeth as well.  I will be showing more teeth from the Smoky Hill Chalk in the next post.

 

[siteseer]

More Smoky Hill Chalk teeth.  I forgot to mention that the teeth in the previous post were collected on a private ranch in Gove County, Kansas.  That's where these are from as well.  The largest tooth is 25mm along the total mesial edge (crown and root).

 

 

[siteseer]

Here's another group of Smoky Hill Chalk teeth.  The largest one is 14mm along the mesial edge.  These teeth were collected by the same person on the same ranch.  As far as I know, they were all collected as float so we have no way of knowing at what level in the chalk they were collected.  It's significant since there are faunal differences (all the organisms) in the lower one-third of the chalk compare to the others and some species might show a trend in size difference through the chalk. 

Edited June 14, 2022 by siteseer

[siteseer]

I'd say this is the last group of Smoky Hill Chalk teeth but I noticed a few more in my collection including a bigger tooth.  The largest tooth in this group is just over 20mm along the greatest mesial edge.

 

 

[Al Dente]

Here’s a variety of Squalicorax yangaensis from the Tar Heel Formation (Campanian) of North Carolina. The largest tooth is slightly longer than 1 inch.

 

 

[Rock Hound]

On 6/19/2022 at 11:33 AM, Al Dente said:

Here’s a variety of Squalicorax yangaensis from the Tar Heel Formation (Campanian) of North Carolina. The largest tooth is slightly longer than 1 inch.

 

 

Those look very much like the teeth I have from the Tombigbee River, in NE Mississippi.

[Al Dente]

5 hours ago, Rock Hound said:

Those look very much like the teeth I have from the Tombigbee River, in NE Mississippi.

Yes, your site must be the same age (Campanian) as my site. I also find lots of S. kaupi and Scapanorhynchus texanus at this site.

[siteseer]

Moving on to the Santonian, here's a tooth from Tyk-Butak, Kazakhstan.  It was labelled Microanacorax praeyangaensis but I think it's Squalicorax falcatus.  It's about 8mm wide and may be a juvenile tooth.

[siteseer]

Here's another Squalicorax tooth from Tyk-Butak, Kazakhstan.  This one (21mm along the total mesial edge) seems to be an early S. kaupi because the crown rises higher from the root on the mesial edge and curve (aka convex mesial cutting edge) rather than gently sloping up from the root as in S. falcatus especially in lateral teeth.  It seems to have  a shorter distal heel too.  It can be hard to say, though, because and as it often is with sharks, these teeth can be variable in shape so it seems you can always find a tooth that doesn't fit with the the others.  Sometimes, they give it a new name.

[siteseer]

I'm getting back to this thread after getting sidetracked posting in other threads over the past few months.  I'm now in the Campanian, a time when we see that S. kaupi has replaced S. falcatus.  When I take a look at the Smoky Hill Chalk teeth earlier in the thread, I see the transition happened somewhere around the late Santonian to early Campanian.  Teeth with a weakly convex mesial cutting edge on the cusp and more of a mesial heel (=blade or shoulder) are indicative of S. falcatus.  Teeth with a more rounded mesial cutting edge on the cusp and lacking a distinct mesial heel are indicative of S. kaupi..  You see some coarser serrations and even compound serrations in S. kaupi.

 

Also. I would say the first two teeth in the June 11 post are S' kaupi rather than S. falcatus and likely came out from higher in the formation while the other teeth could have come from lower to higher in the formation.

 

The tooth below comes from the Eutaw Formation, Tombigbee Sand Member from a site near West Point, Clay County, Mississippi.  It measures about 21mm along the mesial edge from root end to crown tip.  You can see the mesial cutting edge is more rounded  or convex in outline with some coarse serrations that get irregular along with a few compound ones.

 

Edited November 3, 2022 by siteseer

[caterpillar]

Some french Squalicorax

 

Squalicorax kaupi from upper santonian of southwest France - 17mm

 

 

Squalicorax kaupi from upper santonian of southwest France - 22mm

 

 

Squalicorax pristodontus from upper maastrichtian of southwest France - 22mm

 

 

Edited November 3, 2022 by caterpillar

[siteseer]

Here's a group of other teeth from that West Point, MS locality.  The tooth in the upper left is 17mm in slant height; tooth in the upper right is just over 17mm in slant height; tooth in the lower left is 19mm.  The tooth in the lower tight is chipped at the tip but still just over 16mm.  That one might be S. yangaensis but the others are S. kaupi.

 

The tooth in the upper right has an unusually large serration and is chipped next to it likely because that part of the tooth was also enlarged and might have been clipped by an opposing tooth or bite on bone because of it.

 

 

[Al Dente]

47 minutes ago, siteseer said:

That one might be S. yangaensis but the others are S. kaupi.

I’m pretty sure the two on the bottom are S. yangaensis. They both have the typical indentation (red arrows) with the enlarged serrations on the convex portion near the indentation (blue arrows).

 

 

[siteseer]

Okay, thanks.  I received these teeth years ago and didn't really examined them until a few weeks ago.  it's one of those things about getting stuff in lots whether it's a trade or a purchase.  There could be something different in there that you weren't expecting.