Tiny Meg or wishful thinking?

[Desert_survivor]

Hi everyone, I was going through some tiny teeth from a recent trip to Ernst quarries (Bakersfield; round mountain silt; ~ 15 mya) and came across this intriguing little tooth. 

 

It is ~11 mm and serrated on both sides. Is this a tiny meg or just wishful thinking?

[Thecosmilia Trichitoma]

It doesn't seem to be a Megalodon tooth. However, I do not know what it is.

[Praefectus]

I don't think that's a Meg. Megalodon teeth tend to be wider and more triangular in shape.

[DeepTimeIsotopes]

I don't think it's a meg. The serrations seem to be too pronounced. Maybe @Woopaul5or @isurus90064 could chime in. From his photos of his megs from there they seem to have smaller serrations and nearly symmetrical.

See the photos here 

 

[Desert_survivor]

Thanks, everyone, for the thoughts. I am not sure what else from sharktooth hill has serrations other than hemis, Megs, and snaggle tooth shark teeth. I’d welcome any other thoughts on the ID. Thanks!

[Brett Breakin' Rocks]

34 minutes ago, Desert_survivor said:

Thanks, everyone, for the thoughts. I am not sure what else from sharktooth hill has serrations other than hemis, Megs, and snaggle tooth shark teeth. I’d welcome any other thoughts on the ID. Thanks!

Hi there, just wanted to jump in and say this is most likely a Carcharhinus sp. a lower tooth. Maybe someone can nail down a species but that is usually tough since they are all so similar.

 

Cheers,

Brett

[Brett Breakin' Rocks]

37 minutes ago, Desert_survivor said:

Thanks, everyone, for the thoughts. I am not sure what else from sharktooth hill has serrations other than hemis, Megs, and snaggle tooth shark teeth. I’d welcome any other thoughts on the ID. Thanks!

A page from Elasmo that might help you to narrow the hunt.  That deep nutrient groove is gonna help.

 

http://www.elasmo.com/frameMe.html?file=paleo/alter/requiem.html&menu=bin/menu_fauna-alt.html

 

[Desert_survivor]

Thanks @Brett Breakin' Rocks I think that is spot on! I really appreciate the help!

[Brett Breakin' Rocks]

Sure .. I'm not 100% but @caldigger will be able to help to possibly identify to a species level or suggest a third option.

 

Cheers,

Brett

[ziggycardon]

The tooth looks similar to my paleocarcharodon I have, but I am not sure if that's a species that can be found in the area where you hunt.

[Desert_survivor]

5 hours ago, ziggycardon said:

The tooth looks similar to my paleocarcharodon I have, but I am not sure if that's a species that can be found in the area where you hunt.

Thanks. Those do look similar, but I think the paleocarcharodon are more ancient than the Sharktooth Hill bone bed. 

[caldigger]

Your specimen seems a perfect match foe the C. limbatus.  Matching root structure, deep nutrient groove, shape of crown, etc.  I would say, Blacktip it is. 

Nice piece!

[Desert_survivor]

Thanks, Caldigger!

[FossilsAnonymous]

I'm going to have to agree with Brett and Caldigger. I find a lot of those teeth nearby but they are slightly different. The tooth you showed seems similar. Cool anyways!

[isurus90064]

Definitely Carcharhinus

[siteseer]

8 hours ago, caldigger said:

Your specimen seems a perfect match foe the C. limbatus.  Matching root structure, deep nutrient groove, shape of crown, etc.  I would say, Blacktip it is. 

Nice piece!

 

Hi Caldigger,

 

I tend to be cautious about trying to identify Carcharhinus teeth to species when the age is older than Late Miocene-Early Pliocene.  Researchers seem more comfortable with teeth from the Yorktown Formation and Upper Bone Valley Formation because they more closely resemble (or are identical to) modern forms.  The Sharktooth Hill Bonebed is ten million years older than that - teeth of an age closer to what you see from the Calvert Formation of Maryland or Pungo River Formation.  The teeth in many cases are less of a close resemblance and they're smaller on average.  When I look at STH Carcharhinus teeth, I try to sort them into uppers and lowers and subdivide those into teeth with coarsely-serrated cusps vs. finely-serrated main cusps.  Of course, you'll see teeth that are more coarsely-serrated at the base of the cusp grading into finer serrations toward the tip.  You end up with a bunch of teeth many of which don't seem to be very distinct from others.

 

When I look at modern Carcharhinus limbatus, I see tall and slender teeth with fine serrations..  The teeth are also rather straight or angled rather than curved.  Of course, we can't expect blacktip shark teeth to be identical to an apparent ancestor from 15-16 million years ago and I don't know the full range of variation in the teeth of the modern form but I think the tooth shown in this thread should look more like a smaller version of a modern blacktip before calling it one.  Yes, it is rather straight but it looks broader than what I'd expect of an early blacktip.  It also has coarser serrations than I would expect.

 

There's also circumstantial evidence against a blacktip shark being from the Middle Miocene of that part of California.  First, C. limbatus is not known as a fossil from the Miocene-Pleistocene of California.  Today, it's known as a warm-temperate to subtropical shark.  As far as I know, there aren't any confirmed sightings nor catches of blacktips off California though the species has been documented off Ensenada, Mexico so it is realistic that it could range as far north as Santa Barbara or Point Conception during an unusually warm summer/El Nino year.

 

The STH environment has been characterized as warm-temperate but not subtropical.  The Middle Miocene was a warmer time worldwide than we known today but climates were starting to cool after the Early Miocene (the warmest interval since the Early-Mid Eocene).  Hammerheads and Hemipristis are rare teeth in the STH Bonebed so we get the idea that the shark fauna was roughly more like what you'd find off Monterey, CA than anywhere off Baja California.  A blacktip would have frequented the bay/inlet represented by the STH Bonebed but it could have visited on occasion.

 

Anyway, I'm not saying that you're wrong.  I'm just leaning against it without an argument for what species it is.  I've sorted through Bone Valley and Yorktown Formation teeth and ended up with some hard-to-say teeth in those samples too.

 

Jess

 

An example of blacktip teeth I've seen - see also Bigelow and Schroeder (1948):

 

https://www.google.com/search?q=blacktip+shark+teeth&rlz=1C1CHBF_enUS706US706&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiF8eO358_eAhULEHwKHXKGCdsQ_AUIEygB&biw=1069&bih=495#imgrc=spTJ_IzZ22At0M:

 

 

[caldigger]

Then I digress. Just going off the example given.

 

[siteseer]

23 hours ago, caldigger said:

Then I digress. Just going off the example given.

 

I don't think I have personally found a serrated tooth from STH other than Hemi and Meg.  Curious, I'll have to look through my smaller teeth and check.

 

Hi Caldigger,

 

I'm a little confused by what elasmo.com (the source of the guide you're using) because it provides a photo of some teeth also labelled as C. limbatus that don't closely resemble the tooth you attached.  They are long relative to their width but also seem narrower in overall width (root lobe tip to root lobe tip) than  I've seen in modern teeth.  The teeth attached in this post are from the Pungo River Formation (Lee Creek site) which ranges a little older (Early-Middle Miocene) than STH (Middle Miocene).  The serrations are fine on the cutting edges and said to be somewhat coarser on the heels.  The original tooth in question has coarser serrations on the cutting edges and the cusp seems too broad-based and short (relative to the width) to be C. limbatus but it does seem to fit with elasmo's Lee Creek grouping. (2016

 

As for the other elasmo.com tooth you attached as a guide, that is an unusually large Carcharhinus tooth for the STH Bonebed.  I should add that it does fit with how Boyd (2016) interprets C. limbatus.  It leaves me wondering if I'm clinging to an unrealistically-narrow view of the blacktip shark.  I just have a hard time allowing the chronologic range of a modern species so far into the Miocene even though the bull shark does seem to do that.  The thing with the bull shark, though, is that its Early-Middle Miocene teeth do look more the same as modern teeth than the C. limbatus tooth figures I was looking at last night and today.

 

Jess

 

P.S.  Let's reel in a few more shark people and get their opinions: @Al Dente @sixgill pete @sagacious .  I also want more analysis from @isurus90064

 

 

Boyd, B.  2016.

Fossil sharks and rays of Gainesville creeks Alachua County, Florida: Hawthorn Group (middle Miocene to lower Pliocene).  Florida Paleontological Society Special Papers.  40 pages.

 

 

[caldigger]

From Joe Cocke's " Fossil Shark Teeth of the World".

Stating the Blacktip Shark is common and if found in Kern County, I would assume STH sediments.

[verydeadthings]

I agree with everyone that it's Carcharhinus. I'm more familiar with the modern species, and my memory is rusty (I have since moved on to other research interests), but the shape and serration pattern is somewhat similar to C. albimarginatus (silvertip).Take that with a grain of salt. Shameless plug, you can find my thesis on Carcharhinus shark teeth here (https://www.researchgate.net/publication/316735477_Species_discrimination_in_Carcharhinus_shark_teeth_using_elliptic_Fourier_analysis), it has some modern dentitions, unfortunately low quality versions. I'm attaching a higher quality plate with three silvertip dentitions. Depending on how old it is, you might not want to try to identify it to a modern species. I view most identifications of fossil Carcharhinus teeth as tentative/speculative, it's difficult even with complete modern jaws to differentiate some species (for example bull/java sharks) if you don't have the whole animal.

 

[verydeadthings]

and some blacktip teeth (C. limbatus) for comparison. To me the blacktip teeth are a bit more slender, but of course I have a sample size of three specimens for each species here. A bit more of a notch in the silvertip teeth, the silvertip teeth are a bit more coarsely serrated.

 

[sixgill pete]

On 11/13/2018 at 7:31 PM, siteseer said:

 

Hi Caldigger,

 

I'm a little confused by what elasmo.com (the source of the guide you're using) because it provides a photo of some teeth also labelled as C. limbatus that don't closely resemble the tooth you attached.  They are long relative to their width but also seem narrower in overall width (root lobe tip to root lobe tip) than  I've seen in modern teeth.  The teeth attached in this post are from the Pungo River Formation (Lee Creek site) which ranges a little older (Early-Middle Miocene) than STH (Middle Miocene).  The serrations are fine on the cutting edges and said to be somewhat coarser on the heels.  The original tooth in question has coarser serrations on the cutting edges and the cusp seems too broad-based and short (relative to the width) to be C. limbatus but it does seem to fit with elasmo's Lee Creek grouping. (2016

 

As for the other elasmo.com tooth you attached as a guide, that is an unusually large Carcharhinus tooth for the STH Bonebed.  I should add that it does fit with how Boyd (2016) interprets C. limbatus.  It leaves me wondering if I'm clinging to an unrealistically-narrow view of the blacktip shark.  I just have a hard time allowing the chronologic range of a modern species so far into the Miocene even though the bull shark does seem to do that.  The thing with the bull shark, though, is that its Early-Middle Miocene teeth do look more the same as modern teeth than the C. limbatus tooth figures I was looking at last night and today.

 

Jess

 

P.S.  Let's reel in a few more shark people and get their opinions: @Al Dente @sixgill pete @sagacious .  I also want more analysis from @isurus90064

 

 

Boyd, B.  2016.

Fossil sharks and rays of Gainesville creeks Alachua County, Florida: Hawthorn Group (middle Miocene to lower Pliocene).  Florida Paleontological Society Special Papers.  40 pages.

 

 

 

The teeth pictured from Elasmo, in my opinion are not C. limbatus. First, Purdy et al  (2001) does not include C. limbatus in their fauna list for Lee Creek. Second, at least in my opinion they are very poor matches when compared to an extant dentition. We all know how hard it is to assign most single teeth of Carcharhinus to a species accurately, yet we all try to do it; myself included.

If we start with the Oligocene Belgrade Formation here in eastern N.C. there are a variety of Carcharhinus species found there. Some are not serrate, many are very finely serrated. There is one tooth found there with moderate serrations, that could be an early Dusky like shark, yet the teeth are not as profoundly serrated as the Pungo River (early Miocene) Dusky teeth from lee Creek. Also, many of the similar looking Pungo River Carcharhinus teeth are more serrate than the ones found in the Belgrade. This tells me that in the Carcharhinus lineage the teeth become more serrate as the species evolved. This is just my observation, a hypothesis, not a proven fact. But with that said when you take the tooth in question, from the middle Miocene and compare it to an extant dentition, it is way to serrate to be C. limbatus. The tooth also does not have the same angle distally on the mesial edge that I would expect to see for C. limbatus. 

So with all that said, I think if this tooth were mine, I would label it Carcharhinus undet. This may be a good tooth to get in the hands of a good shark person on the west coast. It may turn up being limbatus, but I have my doubts.

[siteseer]

On 11/13/2018 at 4:42 PM, caldigger said:

From Joe Cocke's " Fossil Shark Teeth of the World".

Stating the Blacktip Shark is common and if found in Kern County, I would assume STH sediments.

 

Yes, in this case I agree that the teeth are most likely from Sharktooth Hill.  You can find older teeth in Kern County (Olcese Sand, Pyramid Hill Sand, etc.) but those teeth look like the lighter-colored, less-mineralized ones from the STH Bonebed.

 

Joe Cocke is one of the most-experienced STH collectors alive and a shark tooth expert but I would have to lean against those first two upper teeth being C. limbatus.  They look more like the copper shark, C. brachyurus following unpublished research by Joseph Arndt. 

 

Jess

 

 

[sixgill pete]

13 minutes ago, siteseer said:

 

Yes, in this case I agree that the teeth are most likely from Sharktooth Hill.  You can find older teeth in Kern County (Olcese Sand, Pyramid Hill Sand, etc.) but those teeth look like the lighter-colored, less-mineralized ones from the STH Bonebed.

 

Joe Cocke is one of the most-experienced STH collectors alive and a shark tooth expert but I would have to lean against those first two upper teeth being C. limbatus.  They look more like the copper shark, C. brachyurus following unpublished research by Joseph Arndt. 

 

Jess

 

 

Jess, I agree that the top two left teeth are probably not C. limbatus and they do look like C. brachyurus. The bottom row, quite honestly could be from a number of Carcharhinus species and one of them could be Negaprion in my opinion. I have not seen them listed as part of the STH fauna, but the extant species is known from the Pacific coast of northern South America, Central America and Mexico including the Baja California area. I have the book that Doren is using as a reference, a signed copy actually. I use it as a reference, but rarely for identification.

[siteseer]

8 hours ago, sixgill pete said:

 

The teeth pictured from Elasmo, in my opinion are not C. limbatus. First, Purdy et al  (2001) does not include C. limbatus in their fauna list for Lee Creek. Second, at least in my opinion they are very poor matches when compared to an extant dentition. We all know how hard it is to assign most single teeth of Carcharhinus to a species accurately, yet we all try to do it; myself included.

If we start with the Oligocene Belgrade Formation here in eastern N.C. there are a variety of Carcharhinus species found there. Some are not serrate, many are very finely serrated. There is one tooth found there with moderate serrations, that could be an early Dusky like shark, yet the teeth are not as profoundly serrated as the Pungo River (early Miocene) Dusky teeth from lee Creek. Also, many of the similar looking Pungo River Carcharhinus teeth are more serrate than the ones found in the Belgrade. This tells me that in the Carcharhinus lineage the teeth become more serrate as the species evolved. This is just my observation, a hypothesis, not a proven fact. But with that said when you take the tooth in question, from the middle Miocene and compare it to an extant dentition, it is way to serrate to be C. limbatus. The tooth also does not have the same angle distally on the mesial edge that I would expect to see for C. limbatus. 

So with all that said, I think if this tooth were mine, I would label it Carcharhinus undet. This may be a good tooth to get in the hands of a good shark person on the west coast. It may turn up being limbatus, but I have my doubts.

 

Hi Don,

 

Thanks for getting in on the discussion.  The origin of Carcharhinus is murky but it appears to me that it descended from Abdounia or a close relative sometime in the Early-Mid Eocene.  Elasmo shows a partial tooth from the Late Paleocene that may be a Carcharhinus ancestor.  I think the oldest Carcharhinus teeth I've seen have come from the "Lisbon Sand" of Alabama but teeth from there tend to show some water wear so it's hard to start from there.  Teeth coming out of the Late Eocene of Morocco (Spanish Sahara) can be unsearrated to weakly-serrated so I know what you mean.  Though we start seeing a growing diversity within Carcharhinus in the Early Miocene at sites like Lee Creek, there's an interesting  paper (Adnet et al, 2007) that indicates the radiation may have been well underway in the Pakistan area (Tethys Sea).  By the Middle Miocene some species became much larger and better-adapted for preying on and scavenging larger vertebrates and developing serrated teeth helped with that.

 

Yeah, it's tough with isolated teeth.

 

Jess

 

 

Adnet, S.,  P.O. Antoine,. S.R.H. Baqri, J.Y. Crochet, L. Marivaux, J.L. Welcomme, and G. Metais.  2007.
New tropical carcharhinids (Chondrichthyes, Carcharhiniformes) from the late Eocene-early Oligocene of Balochistan, Pakistan: Paleoenvironmental and paleogeographic implications.  Journal of Asian Earth Sciences, 30: 303–323