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Another Bakersfield Shark Tooth Id Needed


Vball

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post-1286-125437914019_thumb.jpgpost-1286-12543791566338_thumb.jpg

Maybe small Sphyrna cf zygaena(hammerhead)??? I'm leaning more towards Rhizoprionodon sp? — Sharpnose shark which have been found at Shark tooth hill

It is right at .30 inches

Thanks in advance for any help on this.

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It does look like Rhizoprionodon, but I'm not aware that they are found at STH. Elasmo doesn't mention them on their site, and neither does anywhere else I can find. That being said, I can't find anything else that looks like your teeth. Do you know for a fact that Rhizoprionodons are at STH?

There's no limit to what you can accomplish when you're supposed to be doing something else

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It does look like Rhizoprionodon, but I'm not aware that they are found at STH. Elasmo doesn't mention them on their site, and neither does anywhere else I can find. That being said, I can't find anything else that looks like your teeth. Do you know for a fact that Rhizoprionodons are at STH?

I found this Fauna Doc. while trying to ID a previous tooth. Then I couldn't find the site again so I'm Glad I copied it. EDIT I found the site again it comes from the Buena Vista Museum Of Natural History. If not for this doc I would have been clueless as well. I was hoping someone had seen this tooth from there or heard about it at least. I can't believe I got a rare tooth like this in an ebay auction of teeth still in matrix.

Sharktooth Hill Fauna, circa 2003

List of taxa from the Sharktooth Hill Local Fauna The taxa with + are previously unreported in the literature. Those with * are taxa whose holotypes were collected in the Sharktooth Hill bonebed. Taxa with a question mark are considered as undetermined or unknown until further research is completed on that certain taxa or species.

(Note: Fauna List is still being looked into and new species maybe added to the list or some species maybe taken off the list for scientific accuracy.)

Phylum: Chordata (vertebrates)

Class Chondrichthyes

Superorder Selachoidii (Sharks)

Order Hexanchiformes

Family Hexanchidae (six-gilled & seven-gilled sharks)

*Hexanchus andersoni (Jordon, 1907) (six-gilled shark)

Notorhynchus sp. (seven-gilled shark)

Order Heterodontiformes

Family Heterodontidae (bullhead "horn" shark)

Heterodontus sp

Order Squaliformes

Family Squalidae (dogfish sharks)

*Squalus occidentalis (Agassiz, 1843)

Squalus serriculus (Jordon & Hannibal, 1923)

Family Echinorhinidae (bramble shark)

*Enchinorhinus blakei (Agassiz, 1856)

Order Squatinformes

Family Squatinidae (angel shark)

*Squatina lerichei (Jordon & Beal, 1913)

Order Lamniformes

Family Megachasmidae (mega-mouth shark)

+Megachasma sp.

Family Odontaspidae (sand tiger sharks)

+Odontaspis sp.

? Carcharias (Odontaspis) cuspidata (Agassiz, 1843)

Family Cetorhinidae (basking shark)

Cetorhinus cf. maximus (Gunner, 1765) (basking shark)

Family Alopidae (thresher shark)

Alopius ? latidens (Leriche, 1909) (thresher shark)

Family Lamnidae (Mako sharks)

Isurus planus or plana (Agassiz, 1856) (hooked-tooth Mako shark)

Isurus hastalis (Agassiz, 1843) (giant Mako shark)

Isurus retroflexus (Agassiz, 1843) (Longfin Mako shark)

Isurus desori (shortfin Mako shark)

Isurus sp

Family Otodontidae (Mega-teeths and Great White Sharks)

Carcharocles megalodon (Agassiz, 1837) (Mega-tooth)

+Parotodus benedeni (LeHon, 1871) (false-tooth Mako shark)

Order Carcharhiniformes

Family Carcharhinidae (tiger sharks, requiem sharks)

*Galeocerdo aduncus (Agassiz, 1843) (tiger shark)

*Galeocerdo contortus (Gibbes, 1849) (tiger shark)

Rhizoprinodon sp. (sharpnose shark)

+Negaprion antiquus (lemon shark)

*Carcharhinus antiquus (Agassiz, 1856) (gray shark)

Carcharhinus cf. egertoni (Agassiz, 1843) (requiem shark)

Carcharhinus cf. limbatus (Valenciennes, 1839) (blacktip shark)

Family Hemigaleidae (weasel "snaggletooth" sharks)

+Genus/species undetermined

Hemipristis serra (Agassiz, 1843) (snaggletooth "Indian Ocean" shark)

Family Triakidae (hound sharks)

Galeorhinus sp? (tope shark)

+Mustelus sp. (smooth-hound shark)

*Triakis beali (Jordon, 1919) (hound shark)

Family Scyliorhinidae (catsharks)

Scyliorhinus sp. (catshark)

+Cephaloscyllium sp. (swellshark)

Family Sphyrnidae (hammerhead shark)

Sphyrna cf zygaena (Linnaeus, 1758)

Family Prisitiophoridae

Pristiophorus sp (sawfish)

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Thanks for your help guys. I was hoping someone knew for sure that this is a tooth found in the STH fauna. Since it is on the list above I'm going to label it as Rhizoprionodon sp. Even though like you guys said there seems to be no other mention of it.

Thanks, Vball

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post-1286-125437914019_thumb.jpgpost-1286-12543791566338_thumb.jpg

Maybe small Sphyrna cf zygaena(hammerhead)??? I'm leaning more towards Rhizoprionodon sp? — Sharpnose shark which have been found at Shark tooth hill

It is right at .30 inches

Thanks in advance for any help on this.

Are those serrations I see on the cutting edges? Rhizoprionodon does not have serrated edges. The mesial cutting edge should also have a more clearly concave contour to be Rhizoprionodon. If they are serrations (weak though they may be), it could be either a Carcharhinus or a Sphyrna tooth.

I have seen teeth from the STH bonebed that resemble Rhizoprionodon (uncommon finds even after doing a lot of screening) but they also look like those from a small, more slender-tipped hammerhead.

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Are those serrations I see on the cutting edges? Rhizoprionodon does not have serrated edges. The mesial cutting edge should also have a more clearly concave contour to be Rhizoprionodon. If they are serrations (weak though they may be), it could be either a Carcharhinus or a Sphyrna tooth.

I have seen teeth from the STH bonebed that resemble Rhizoprionodon (uncommon finds even after doing a lot of screening) but they also look like those from a small, more slender-tipped hammerhead.

It does have some sort of serrations but they look more jagged like this pic from the Elasmo site of a Rhizoprionodon cf acutus — Upper lateral From Lee Creek

post-1286-12546175905768_thumb.jpg

Here is alittle better shot of the edges

post-1286-12546183138558_thumb.jpg

I'm with you though it isn't quite the same even though the root is an almost perfect match to Rhizoprionodon.

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post-1286-125437914019_thumb.jpgpost-1286-12543791566338_thumb.jpg

Maybe small Sphyrna cf zygaena(hammerhead)??? I'm leaning more towards Rhizoprionodon sp? — Sharpnose shark which have been found at Shark tooth hill

It is right at .30 inches

Thanks in advance for any help on this.

Rhizoprionodon sp I have a few in my collection but its not a hammerhead I have a ton of them lol Summerville S.C. is full of them!!!!!

"Not everything that counts can be counted, and not everything that can be counted counts." Albert Einstein

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It does have some sort of serrations but they look more jagged like this pic from the Elasmo site of a Rhizoprionodon cf acutus — Upper lateral From Lee Creek

post-1286-12546175905768_thumb.jpg

Here is alittle better shot of the edges

post-1286-12546183138558_thumb.jpg

I'm with you though it isn't quite the same even though the root is an almost perfect match to Rhizoprionodon.

I was going by Cappetta's 1987 Handbook. I should have gone to Purdy et al. (2001), the Lee Creek volume that covers fishes, reptiles, and birds although it's tough to account for every unusual tooth. They do not figure a tooth like the elasmo.com drawing except for perhaps Carcharhinus macloti, though I should add that Jim Bourdon appears to have found quite a few tooth-forms not figured in the volume. In their review Rhizoprionodon is listed as questionable because its diagnosis is almost the same as two other carcharhinid genera. For me in the STH tooth, the lack of a clearly concave mesial edge takes Rhizoprionodon out of contention.

Purdy et al do note: "Relative to their width, the crowns in sphyrnid teeth are higher than those of Rhizoprionodon, and the primary cusp is relatively wider." However, their ID of Figure 57, specimen "e" would seem to be better grouped with Sphyrna according to their remarks. The STH tooth is also rather wide towards its cusp base. The cusp is more slender and more sharply-tipped in Rhizoprionodon.

It's hard to say but if pressed for my opinion I would say it's a Carcharhinus tooth.

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I was going by Cappetta's 1987 Handbook. I should have gone to Purdy et al. (2001), the Lee Creek volume that covers fishes, reptiles, and birds although it's tough to account for every unusual tooth. They do not figure a tooth a tooth like the elasmo.com drawing except for perhaps Carcharhinus macloti, though I should add that Jim Bourdon appears to have found quite a few tooth-forms not figured in the volume. In their review Rhizoprionodon is listed as questionable because its diagnosis is almost the same as two other carcharhinid genera. For me in the STH tooth, the lack of a clearly concave mesial edge takes Rhizoprionodon out of contention.

Purdy et al do note: "Relative to their width, the crowns in sphyrnid teeth are higher than those of Rhizoprionodon, and the primary cusp is relatively wider." However, their ID of Figure 57, specimen "e" would seem to be better grouped with Sphyrna according to their remarks. The STH tooth is also rather wide towards its cusp base. The cusp is more slender and more sharply-tipped in Rhizoprionodon.

It's hard to say but if pressed for my opinion I would say it's a Carcharhinus tooth.

Ok I think I see what your saying. Since it really doesn't match the definition of Rhizoprionodon I should label it Carcharhinus sp. or Carcharhinus (?)

I guess My only other Question would be do you think that the Buena Vista Fauna list above is refering to this tooth as Rhizoprionodon Sp.?

Thanks so much for your help I can tell you know your shark teeth.

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Ok I think I see what your saying. Since it really doesn't match the definition of Rhizoprionodon I should label it Carcharhinus sp. or Carcharhinus (?)

I guess My only other Question would be do you think that the Buena Vista Fauna list above is refering to this tooth as Rhizoprionodon Sp.?

Thanks so much for your help I can tell you know your shark teeth.

Yeah, I would call it Carcharhinus sp. because it could just be an oddball variation of a common species there. It's tough naming Carcharhinus teeth to species. You can group the teeth into uppers and lowers and then separate uppers with coarse serrations on the heels but fine serrations on the cutting edges and other uppers with fine serrations on the edges and the heels but then you will look at a couple of teeth with a couple of coarse serrations among the fine serrations or some other tooth that seems to be of an intermediate morphology between apparent species. How do you identify those? The Middle Miocene is just long enough ago that some of those teeth could belong to early representatives of modern species or perhaps their immediate ancestors or extinct relatives of immediate ancestors. That's the world of shark tooth collecting.

The Buena Vista Museum's fauna list is a compilation that started with the list in Mitchell's 1965 book, "History of Research at Sharktooth Hill, Kern County, California." It was then periodically updated by a museum volunteer who is not a paleontologist but who did a lot of work trying to stay on top of both past and present journal articles on STH organisms. Various other individuals were involved in identifying specimens and putting them out for display.

I would have to check to see if the museum has a tooth on display identified as a sharpnose shark. I will look through my teeth and try to photograph something that might be one.

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Yeah, I would call it Carcharhinus sp. because it could just be an oddball variation of a common species there. It's tough naming Carcharhinus teeth to species. You can group the teeth into uppers and lowers and then separate uppers with coarse serrations on the heels but fine serrations on the cutting edges and other uppers with fine serrations on the edges and the heels but then you will look at a couple of teeth with a couple of coarse serrations among the fine serrations or some other tooth that seems to be of an intermediate morphology between apparent species. How do you identify those? The Middle Miocene is just long enough ago that some of those teeth could belong to early representatives of modern species or perhaps their immediate ancestors or extinct relatives of immediate ancestors. That's the world of shark tooth collecting.

The Buena Vista Museum's fauna list is a compilation that started with the list in Mitchell's 1965 book, "History of Research at Sharktooth Hill, Kern County, California." It was then periodically updated by a museum volunteer who is not a paleontologist but who did a lot of work trying to stay on top of both past and present journal articles on STH organisms. Various other individuals were involved in identifying specimens and putting them out for display.

I would have to check to see if the museum has a tooth on display identified as a sharpnose shark. I will look through my teeth and try to photograph something that might be one.

Ok after careful study and your help I've come to this conclusion. I believe it is an upper position 14 Carcharhinus limbatus for a few reasons. #1 The nutrient groove position (it is offset) #2 The fact that there was another tooth in the batch I have from this shark #3 The angle of the tooth is a perfect match. The position made the root look different, that and the size. also see below

I found this on elasmo it was the only good pic I could find but the copper shark is close enough to the blacktip to get an good idea what it might look like. post-1286-12548956068663_thumb.jpg

Let me know what you guys think??

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Ok after careful study and your help I've come to this conclusion. I believe it is an upper position 14 Carcharhinus limbatus for a few reasons. #1 The nutrient groove position (it is offset) #2 The fact that there was another tooth in the batch I have from this shark #3 The angle of the tooth is a perfect match. The position made the root look different, that and the size. also see below

I found this on elasmo it was the only good pic I could find but the copper shark is close enough to the blacktip to get an good idea what it might look like. post-1286-12548956068663_thumb.jpg

Let me know what you guys think??

I think you are closer with the copper shark, Carcharhinus brachyurus. C. limbatus has straighter upper teeth than I have ever seen from the bonebed or any other fossil site in California, though some lower teeth bear fine serrations on the cutting edges and heels as shown in Bigelow and Schroeder (1948: p. 348), so that must be considered. However, limbatus lives today in tropical and subtropical waters and the STH environment was warm-temperate with tropical forms rare or absent (Hemipristis rare, large Negaprion absent but rather common in same-age rocks of Baja California), so I don't think limbatus was there.

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