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HoppeHunting

Smooth Tiger

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HoppeHunting

Hey all,

 

This isn't so much a Fossil ID as it is a question. Can Tiger Shark teeth have smooth cutting edges if they're worn down enough? If so, then this tooth would certainly attest to that. I'm fairly certain that it came from the jaws of Physogaleus contortus (technically not a Tiger, but I call it one anyway). The strange thing is that it almost entirely lacks a defining feature of Tiger Shark teeth: serrations! The only evidence of a serrated edge are on the distal shoulder, but even there they are incredibly worn down. On the blade of the crown itself, the cutting edge is perfectly smooth, like a Hammerhead tooth. My question here is not if teeth can be worn down, because I know this. Some are so worn that they become unidentifiable! My question, rather, is why is the rest of this tooth hardly worn down at all while the serrations are doing a disappearing act? Do serrations on fossilized sharks teeth erode faster than the rest of the tooth? Thanks in advance for any help.

 

 

IMG_5950.jpg

IMG_5947.jpg

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Anomotodon

Eocene Physogaleus, for instance, had much weaker mesial serrations or even none. Though they could be water-worn too.

Edit: Serrations could be easier worn since they are very delicate structures - much like thin lateral cusplets but located on the carina. Also it is much harder to notice that the crown is worn since enamel is fairly thick there and shiny anyway.

 

Female Physogaleus

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Kimi64

I am new to hunting, not even at a year yet, but I have a tooth very similar to yours. I will take a photo & post it tomorrow. Ready to turn the lights out here & if I start photographing teeth again, I won't stop, LOL. 

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Kimi64

Or, I can just leave it to the experts,:headscratch:

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HoppeHunting
2 minutes ago, Anomotodon said:

Eocene Physogaleus, for instance, had much weaker mesial serrations or even none.

Interesting. However, I forget to mention that this tooth was found at Brownie's Beach, Calvert Formation. I believe you can only find Miocene fossils at this site.

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ynot
49 minutes ago, HoppeFossilHunting said:

 Physogaleus contortus 

Not all Physogaleus contortus teeth have serrations.

Your tooth look very worn, so no way to say if it was serrated or not.

 

 

 

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caldigger

 Here's a few of mine from STH mid. Miocene with extremely fine to no serrations detected.

Throw a bit of sand and tossing about in the waves into the mix and any sign of them could easily disappear.

20180227_211817.jpg

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HoppeHunting
12 minutes ago, caldigger said:

Miocene with extremely fine to no serrations detected. Throw a bit of sand and tossing about in the waves into the mix and any sign of them could easily disappear.

Wow! I guess this isn't so uncommon after all. I'd expect the smooth edges to be more common in Physogaleus than in Galeocerdo because the latter has more coarse serrations, which would not erode as easily. I'm sure it still happens with traditional Tigers, but the abundance of smooth edges seen in your examples leads me to believe it's much more common with Physogaleus because of its fine serrations. Fair conclusion?

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ynot
7 hours ago, HoppeFossilHunting said:

the abundance of smooth edges seen in your examples leads me to believe it's much more common with Physogaleus because of its fine serrations. Fair conclusion?

No, the teeth that caldigger showed are pristine and have little to no wear.

The ones without serrations never had any.

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HoppeHunting
5 minutes ago, ynot said:

The ones without serrations never had any.

Okay, so some P. contortus teeth have no serrations to begin with? I read that this was true for other species of the genus from earlier time periods, but I thought that the Miocene Tigers always have the serrations if they're pristine. All of the P. contortus teeth from Miocene sites I've collected so far have shown obvious signs of serrations, even if worn. Is it possible that the smooth-edged teeth come from another species of the same genus? Otherwise, why would we see such a major difference in teeth from the same species? Serrations can be a defining feature of a species. It's definitely possible for there to be oddball teeth, like how some Makos can be occasionally found with cusplets. Is that similar to the case here?

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Fossildude19
7 hours ago, HoppeFossilHunting said:

Hey all,

 

This isn't so much a Fossil ID as it is a question.

 

I've moved the topic to Questions and Answers.  ;) 

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Troodon
7 hours ago, HoppeFossilHunting said:

Okay, so some P. contortus teeth have no serrations to begin with? I read that this was true for other species of the genus from earlier time periods, but I thought that the Miocene Tigers always have the serrations if they're pristine. All of the P. contortus teeth from Miocene sites I've collected so far have shown obvious signs of serrations, even if worn. Is it possible that the smooth-edged teeth come from another species of the same genus? Otherwise, why would we see such a major difference in teeth from the same species? Serrations can be a defining feature of a species. It's definitely possible for there to be oddball teeth, like how some Makos can be occasionally found with cusplets. Is that similar to the case here?

P. contortus is an extinct genus of requiem shark not tiger and MAY have weak serrations on the mesial edge that can easily wear off.   

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HoppeHunting
8 hours ago, Troodon said:

P. contortus is an extinct genus of requiem shark not tiger.  

Right. I've seen it listed as "Tiger-like shark" and since the teeth are very similar I tend to just call them Tigers. If calling Carcharodon hastalis a "Mako" is acceptable, then I'm surely I can get away with this. ;) But yes, technically it is not a Tiger. While we're on the topic, why does Physogaleus not have a common name? I believe @WhodamanHD has brought this up before. Is it because it's such a small genus and there are no living species today? I still think we should be able to refer to such a common find with a more simple name, but "Physo" does sound pretty cool for short. Is it even possible for it to acquire a true common name, or did that chance die along with the genus?

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WhodamanHD
9 minutes ago, HoppeFossilHunting said:

Right. I've seen it listed as "Tiger-like shark" and since the teeth are very similar I tend to just call them Tigers. If calling Carcharodon hastalis a "Mako" is acceptable, then I'm surely I can get away with this. ;) But yes, technically it is not a Tiger. While we're on the topic, why does Physogaleus not have a common name? I believe @WhodamanHD has brought this up before. Is it because it's such a small genus and there are no living species today? I still think we should be able to refer to such a common find with a more simple name, but "Physo" does sound pretty cool for short. Is it even possible for it to acquire a true common name, or did that chance die along with the genus?

Bretton Kent calls them Galeocerdo contortus, meaning it’s a tiger, albeit the book is old (not sure how old. And it is great, thanks for suggesting it @Troodon!)

and others still say it’s within the genus. However, most others (including myself) say that it belongs in its own genus, Physogaleus. Some extant creatures have seperate common names for species, some for one genus, and some for multiple genera or even larger (think water bears or old world monkeys). It may be appropriate to call them requiem sharks, though if they were alive today I think they would be called pygmy tiger sharks or false tiger sharks. But I am okay with physos or maybe something new (if that name would ever catch on). I’m in support of grizzly shark:D

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WhodamanHD

Would like to add (as I forgot) that Kent does have Physogaleus but another species ( secundus and maybe tertius)contortus  being placed in Galeocerdo

he also calls them sharpnose sharks.

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