Isurus Hastalis Tooth From Miocene Epoch?

[Doerr02]

I found this fossilized tooth in South Carolina and think it is an Isurus Hastalis (extinct Mako Shark) tooth from the Miocene Epoch. I read that the genus name "Isurus" is sometimes considered "Cosmopolitodus" to clarify that it is the ancestor to C. carcharias. Maybe somebody will be able to clear that confusion up for me. It is approximately 49 mm in length from the top of the tooth to the tip. I am not sure what the correct way to size shark teeth is, so I could be measuring this incorrectly. I think it is a Isurus Hastalis tooth instead of a fossilized Carcharodon carcharias (great white shark) tooth since there are no serrations along the edges.

[Northern Sharks]

I won't get into Isurus vs. Cosmopolitodus, but your identification is correct. Shark teeth such as this are measured along the slant from the tip to the furthest point on the root. Cow sharks and a lot of paleozoic sharks are measured in length from front to back.

Edited October 14, 2013 by Northern Sharks

[sixgill pete]

You definitely have a hastalis, and a rather nice one too. Congrats!!

[Doerr02]

Awesome! I have hundreds of small black fossilized shark teeth I meticulously collected on Myrtle Beach that I'm going to try and identify next. Then once I've attempted identification, I'll run them by the forum to be sure. I need to read up on the types of sediment the teeth were fossilized in so I know why some are brownish vs black.

[RickCalif]

Congrats on what is indeed a Hastalis.....The Isurus and Cosmopolitodus, along with the great White Lineage thing......is best left alone...lol The Hastalis... probably one of the most common teeth where I dig at which is Sharktooth Hill outside of Bakersfield California...a few collected over 3" I do enjoy the Florida beaches....they're always fun to collect at.....Manasota Key always seems to have plenty of teeth..plenty of Sand, Lemon, Sandbar and Bull Shark Teeth....have fun with the I.D.'s

[Megatooth Collector]

In case you are interested, here are a few teeth in my collection showing what many support as the evolution for the modern great white shark. Starting on the left is a Isurus Hastalis (broad tooth mako) like your tooth on the left, then two transitional teeth partial serrations (C. Hubbellii), and then a fossilized great white and last a modern day great white on the right.

[MakoMeCrazy]

In case you are interested, here are a few teeth in my collection showing what many support as the evolution for the modern great white shark. Starting on the left is a Isurus Hastalis (broad tooth mako) like your tooth on the left, then two transitional teeth partial serrations (C. Hubbellii), and then a fossilized great white and last a modern day great white on the right.

Where is the one on the far left from?

[the tatter]

Beautifull teeth

[Megatooth Collector]

The one on the left is from South Carolina.. nothing too exotic but still very pretty. The two transitional teeth are both from Chilean sites, and the fossilized great white from Georgia.

Edited October 30, 2013 by Megatooth Collector

[paco]

In case you are interested, here are a few teeth in my collection showing what many support as the evolution for the modern great white shark. Starting on the left is a Isurus Hastalis (broad tooth mako) like your tooth on the left, then two transitional teeth partial serrations (C. Hubbellii), and then a fossilized great white and last a modern day great white on the right.

Nice "evolutionary" display!

[Doerr02]

I agree with paco! Thanks for sharing that pic, I hadn't even heard of C. Hubbellii. It just opened my eyes to how frustrating and fascinating studying marine lineages of species must be; so many missing puzzle pieces are just scattered all over the ocean. Someday when I can afford my own sequencing lab equipment I'll have to see what I can find (It won't be anything somebody didn't already know, but it would still be fun:).

[siteseer]

It's worth noting that the full name of C. hubbelli is Carcharodon hubbelli. It links hastalis to carcharias without a doubt though most scientists and collectors had already made that connection from numerous isolated teeth found in California and Peru over the past few decades. From that it can be concluded that the genus that could contain carcharias should also contain hubbelli and hastalis. Therefore, hastalis belongs within Carcharodon also.

The thing to keep in mind with all the name changes seen in biology is that each name is a proposal open to further investigation. If evidence appears that puts a name in question, then it may end up being discarded in favor of a better-supported name. I think the hubbelli jaws put the particular question of great white ancestry to rest so Carcharodon hastalis is going to be the name that will survive in technical usage. Old names die hard though. Some people will still use Isurus or Cosmopolitodus for a while.

A remaining question might be, "Well, what about Cosmopolitodus?" The name "Carcharodon" has priority over "Cosmopolitodus" (it was officially used for the same shark species before Cosmopolitodus was) so Carcharodon wins as the official name.

There has been discussion about the great white's ancestry on this forum before so you can search for that under "Cosmopolitodus" or Carcharodon. You can track down the recent article that described hubbelli too if you want a more detailed view. Here's a link to the abstract:

http://novataxa.blogspot.com/2012/11/2012-carcharodon-hubbelli.html.

I agree with paco! Thanks for sharing that pic, I hadn't even heard of C. Hubbellii. It just opened my eyes to how frustrating and fascinating studying marine lineages of species must be; so many missing puzzle pieces are just scattered all over the ocean. Someday when I can afford my own sequencing lab equipment I'll have to see what I can find (It won't be anything somebody didn't already know, but it would still be fun:).

[barry maness]

I notice the indentation on the distal side of the crown, just below the root.  Pathalogical?

[sagacious]

13 hours ago, barry maness said:

I notice the indentation on the distal side of the crown, just below the root.  Pathalogical?

 

Larger photos would be better, but the indentation in the tooth pictured above appears to be a notch caused by the tooth coming into contact with another tooth from the same shark -- either before or after that tooth was shed. Sometimes a shed tooth will remain embedded in a prey item, and is subsequently bitten by the feeding shark, leaving marks on one or both teeth. It's a tooth with a "bite" mark from it's owner.

 

I have a number of similarly bitten C. hastalis and C. carcharias teeth in my collection. At one time, careful inspection with magnification revealed that approximately 15% of the larger C. carcharias teeth in my collection had distinct bite marks of varying degree. Some have one large notch, like the tooth above, and some have a series of grooves or notches along one side after apparently sustaining multiple bites. Although I haven't updated the figure as my collection has grown, it's clear that both shed and unshed shark teeth may receive bite marks during routine feeding, most probably, when lodged in carcasses large and/or tough enough to retain shed teeth. Fossil bite marks like this are evidence of, and shed light upon, a specific aspect of trophic interaction toward the top of the food chain, although I haven't seen much published about this with respect to bite marks on shark teeth.

 

Below is a fossil Great White shark tooth with several bite marks.