Florida Jax shark teeth

[aurora5us]

Found last two days at Atlantic beach Jacksonville Florida. First time. Not sure what they are from

[debivort]

First tooth looks like a Carcharinus upper, perhaps bull shark. Second looks like Carcharodon hastalis to me.

[digit]

Agreed.

 

 

Cheers.

 

-Ken

[hemipristis]

top: Carcharhinus plumbeus, sandbar shark

[Meatasaurus93]

For the second one, I'm in the C. hastalis camp.

[Meganeura]

7 hours ago, hemipristis said:

top: Carcharhinus plumbeus, sandbar shark

Okay so I need to know - do you know your Carcharhinus from each other via learning or do you have like a resource you compare em to? And regardless of the answer - how do you distinguish between sandbar, grey, bronze, bull, etc?

[hemipristis]

16 hours ago, Meganeura said:

Okay so I need to know - do you know your Carcharhinus from each other via learning or do you have like a resource you compare em to? And regardless of the answer - how do you distinguish between sandbar, grey, bronze, bull, etc?

I have spent a ridiculous amount of time staring at my shark tooth collection and comparing them to references.    I have a large number of Carcharhinus teeth from the Chesapeake and Florida, and several times that from Lee Creek. These were what I started with. I compared them to  the reference library that I use. The seed references were the elasmo.com website, the Smithsonian Lee Creek Vol. iII, and the Guide to Sharks of the Chesapeake Bay.  I augmented this reference list over time by downloading (legally) scientific journal articles (I get them free from my scribd.com membership).  The references are global, and provide a nice perspective. Warning though: not all references are created equal, so be careful. 

 

There are certain characteristics that one learns to spot if you look at enough teeth, and knowledge of the tooth's location is important because it limits the possibilities. Also get to know tooth morphology and the importance of mouth position.  Locational information allows you to develop a list of possible suspects, and eliminate those that are unlikely. For instance, lemon sharks are warm-water, and they are not common finds in the Chesapeake. So when I"m looking at at tooth from the Chesapeake, I keep in mind that it is unlikely to be a lemon.  Carcharhinus tooth ID It takes a lot of practice, and to provide a "cheat sheet" for these teeth would be too long to summarize in a forum post, unfortunately.  But to give you some idea, here is what I saw when I looked at the tooth in this thread:

• Carcharhinus shape;
• Generally large tooth (i.e., >1cm). This limits us to the following likely suspects: bull, dusky, Caribbean Reef, Galapagos, sandbar oceanic white tip.  There are a few others that are current species and are only cited as fossils in the Central American literature. I"m only getting familiar with these, and they don't seem common in US East Coast fossil literature, so I"ll roll the dice and put those aside.
• Root extends far down the blade on the labial side; This is a trait common to dusky and sandbar
• Erect, nearly symmetrical, no shoulder notches, equilateral triangle. This eliminates all but bull, sandbar and oceanic white tip except for the A1 position in the other large teeth
• Serrations generally are not complex. This tends to be the case for bull and sandbar, and eliminates dusky.
• Serrations are pretty uniform. This eliminates dusky, Caribbean Reef, Galapagos, oceanic white tip
• And the most defining characteristic was that the tooth appears to be rather thin in labio-lingual cross-section. This is the defining characteristic for C. plumbeus.

 

Rules of thumb:

1. Utilize various lines of evidence. It's rare to have one distinguishing characteristic. The thin cross-section for C. plumbeus is an exception.
2. Lowers are a nightmare. I generally don't bother except for bull sharks. Their lowers tend to be very robust, larger, with a v-shaped root, and thus distinctive. 
3. The larger Carcharhinus teeth are easier because there are fewer options, and the. defining characteristics are easier to see.  For the teeth <1cm, it gets difficult, and I'd say ~40% of those teeth I just keep as Carcharhinus sp.
4. Nothing is absolute. I"d be lying if I said I didn't re-identify teeth.

 

I hope the helps

Edited October 2, 2022 by hemipristis

[Meganeura]

4 minutes ago, hemipristis said:

I have spent a ridiculous amount of time staring at my shark tooth collection and comparing them to references.    I have a large number of Carcharhinus teeth from the Chesapeake and Florida, and several times that from Lee Creek. These were what I started with. I compared them to  the reference library that I use. The seed references were the elasmo.com website, the Smithsonian Lee Creek Vol. iII, and the Guide to Sharks of the Chesapeake Bay.  I augmented this reference list over time by downloading (legally) scientific journal articles (I get them free from my scribd.com membership).  The references are global, and provide a nice perspective. Warning though: not all references are created equal, so be careful. 

 

There are certain characteristics that one learns to spot if you look at enough teeth, and knowledge of the tooth's location is important because it limits the possibilities. Also get to know tooth morphology and the importance of mouth position.  Locational information allows you to develop a list of possible suspects, and eliminate those that are unlikely. For instance, lemon sharks are warm-water, and they are not common finds in the Chesapeake. So when I"m looking at at tooth from the Chesapeake, I keep in mind that it is unlikely to be a lemon.  Carcharhinus tooth ID It takes a lot of practice, and to provide a "cheat sheet" for these teeth would be too long to summarize in a forum post, unfortunately.  But to give you some idea, here is what I saw when I looked at the tooth in this thread:

• Carcharhinus shape;
• Generally large tooth (i.e., >1cm). This limits us to the following likely suspects: bull, dusky, Caribbean Reef, Galapagos, sandbar oceanic white tip.  There are a few others that are current species and are only cited as fossils in the Central American literature. I"m only getting familiar with these, and they don't seem common in US East Coast fossil literature, so I"ll roll the dice and put those aside.
• Root extends far down the blade on the labial side; This is a trait common to dusky and sandbar
• Erect, nearly symmetrical, no shoulder notches, equilateral triangle. This eliminates all but bull, sandbar and oceanic white tip except for the A1 position in the other large teeth
• Serrations generally are complex. This tends to be the case for bull and sandbar, and eliminates dusky.
• Serrations are pretty uniform. This eliminates dusky, Caribbean Reef, Galapagos, oceanic white tip
• And the most defining characteristic was that the tooth appears to be rather thin in labio-lingual cross-section. This is the defining characteristic for C. plumbeus.

 

Rules of thumb:

1. Utilize various lines of evidence. It's rare to have one distinguishing characteristic. The thin cross-section for C. plumbeus is an exception.
2. Lowers are a nightmare. I generally don't bother except for bull sharks. Their lowers tend to be very robust, larger, with a v-shaped root, and thus distinctive. 
3. The larger Carcharhinus teeth are easier because there are fewer options, and the. defining characteristics are easier to see.  For the teeth <1cm, it gets difficult, and I'd say ~40% of those teeth I just keep as Carcharhinus sp.
4. Nothing is absolute. I"d be lying if I said I didn't re-identify teeth.

 

I hope the helps

This more than helps - this was definitely an incredible help! I mean, I think it'll be a while before I go sort through my Carcharhinus drawer in an attempt to distinguish (Still need to do the same with my tigers...) but this will absolutely be a great help when I do, so thank you very much!

[aurora5us]

I appreciate all of your answers!

 I’m learning a LOT. 

[hemipristis]

4 hours ago, Meganeura said:

This more than helps - this was definitely an incredible help! I mean, I think it'll be a while before I go sort through my Carcharhinus drawer in an attempt to distinguish (Still need to do the same with my tigers...) but this will absolutely be a great help when I do, so thank you very much!

You are welcome!

 

Note:  I noticed an error in my post, which I have corrected.   The bullet should read:

• Serrations generally are not complex