Paleocarcharodon tooth with no data

[britishcanuk]

2 hours ago, Ash said:

Well the old internet adage is once you put it online, its out there for the world. You basically surrender it (unless you put a big ol watermark on it)

I learned that lesson many years ago. Now, if it's a photo I'm worried about, I always slap a copyright watermark on it and only upload low resolution versions. You simply can't control it once it's out there. I get annoyed when my watermark is cropped off, but sadly expect such things when I put it online.

 

its probably people like me who encourage it, since I don't have the motivation or energy to bother chasing people around about it anymore.

 

anways, here are my palaeocarcharodon teeth showing varying degrees of serrations. I'd like to add more of this interesting species to my collection. Anyone of any photos of North American specimens?

[Plax]

On 1/25/2017 at 5:03 PM, siteseer said:

It is a Palaeocarcharodon and I think it is an early/transitional form.  While there appear to be nicks in the cutting edges, it doesn't look like it was carved.  The edges would look like that (irregular with weakly-formed serrations to sort of a wavy appearance to a fine edge in spots - fine enough to be translucent).

 

Teeth like that are found in the Early Paleocene layer.  In the Moroccan phosphates there is Late-Latest Cretaceous, Early Paleocene, Late Paleocene, Early Eocene, and some Middle Eocene (but that stuff tends to be beat-up).  By the time a fossil dealer gets the fossils, it's all mixed together so the site data is lost.  Occasionally, you can find a collector who has personally collected a site or received material from a friend who has collected the site.  It's great when you get some teeth with a detailed label.

 

That tooth could have come out of any site in any of the basins where the Early Paleocene beds are exposed.  It's likely it's from Khouribga in the Ouled Abdoun Basin but fossils from other sites in other basins have also been commercially-available.

 

We've talked about Moroccan stuff before and specifically the sharks.  You should check out this thread:

 

http://www.thefossilforum.com/index.php?/topic/472-finally/

 

 

 

  

 

 

 

what are these early Paleocene (Danian?) Paleocarcharodon transitional from?

[britishcanuk]

17 minutes ago, Plax said:

what are these early Paleocene (Danian?) Paleocarcharodon transitional from?

Perhaps an as yet to be described ancestor somewhere between Cretalamna and Otodus I would think.

[Plax]

reason I ask is that your above pics look like Otodus obliqua to C. auriculatis transition but I know almost nothing about the subject. Am not disagreeing with your identification. The Thanetian Paleocarcharodon I've seen from Maryland and North Carolina are much less robust in the root and more triangular. No pics to back up my assertions though.

[non-remanié]

but but but...guys....elasmo says there's cretaceous paleocarcharodon from the frankstown Mississippi site, so how could the serration event have happened in the early Paleocene???

[Harry Pristis]

As alternatives to a "transition model," is there a possibility that we should consider a "positional model" or even an "ontogenetic model"?

 

I think I notice that the teeth that best show the reduced serrations are the anterior ones.  I'd like to say they are "the large anterior teeth," but some images here don't show a scale. 

 

Here are some small teeth (each a little over an inch), three anterior, two lateral.  All three anterior teeth show prominent, sharp serrations, though in my estimation not as prominent as on the lateral teeth.  Is it possible that anterior teeth normally have reduced serrations? Does a collecting bias for large anterior teeth leads to the idea of two forms of this shark?

 

Or, is it likely that the reduction of serrations is a function of size (age) of the shark?  The small teeth in my image are quite prickly with serrations.  I don't have a growth series for this shark, so I can only speculate that the reduction of serrations on larger anterior teeth is a normal ontogenetic phenomenon.  Further complicating this speculation, larger body size suggests more feeding . . . that is, a larger shark might use its teeth more often and on larger prey.  That might wear down serrations selectively on anterior teeth.

 

Anyway, this is just some brainstorming.  Further images of Paleocarcharodon teeth may be enlightening.

[Troodon]

2 hours ago, non-remanié said:

but but but...guys....elasmo says there's cretaceous paleocarcharodon from the frankstown Mississippi site, so how could the serration event have happened in the early Paleocene???

The statement that follows on elasmo states:

"The time jump between these sediments and the normal occurrence suggests they were transported to this earlier horizon"

 

The Kazakhstan specimens are late Selandian to mid Thanetian in age.

 

Another transitional specimen from Morocco from an Anterior tooth

 

[non-remanié]

That's not what the person who reported them ( Earl Manning)  believes, however.      I'm glad Jim does state that clearly  though.   Still it seems like nothing but a total red herring for them to be posted there at all, both specimens found by one collector who just happens to have been from Florida btw  (pers. con. Earl Manning).   As far as I know many people collected that ridiculously prolific site and these are the only 2 specimens that have come to light and there's no reasonable explanation for the alleged transport or other examples of it.   Connect the dots...

 

3 minutes ago, Troodon said:

The statement that follows on elasmo states:

"The time jump between these sediments and the normal occurrence suggests they were transported to this earlier horizon"

 

 

[non-remanié]

 If the serrations were worn off, the inner osteodentine of the tooth would be exposed at the very least in some of the specimens, but that doesn't seem to be the case.     It's likely a true transitional form, but could also be an atavistic expression of the transitional form.

[Harry Pristis]

3 hours ago, non-remanié said:

 If the serrations were worn off, the inner osteodentine of the tooth would be exposed at the very least in some of the specimens, but that doesn't seem to be the case.     It's likely a true transitional form, but could also be an atavistic expression of the transitional form.

 

I don't think this is true, non-remanie.  There are endless examples of damaged tooth serrations which don't expose osteodentine.  But, possible tooth wear is only incidental to my speculation about positional differences and ontogenetic morphological changes.

[non-remanié]

It is definitely true. Eons of reworking of different species' serrated teeth and the serrations are ALMOST always still evident on these sharks teeth.  The only examples not are from the most heavily tumbled, reworked teeth, which is the exact opposite condition of these pretty much pristine Moroccan examples.

 

The hardest naturally occurring substance in the world, shark tooth enameloid, does not simply get "polished away" uniformly during feeding as would be necessary if your suggestion was feasible.    Serrations are lost when they get sheared off from singular high pressure impacts with bone, almost always revealing the underlying osteodentine or other clear signs of the trauma.

 

I didn't comment on the other aspects of your more reasonable

speculation, so there was no need to repeat yourself. But my guess is that few, if anyone, has come close to seeing enough of these extremely rare transitional form teeth to begin to discuss possible positional discrepancies. But I'd love to be wrong. So  if someone has a bunch of specimens and positions, I'm sure many of us would love to see them.

 

 

 

 

 

 

 

 

 

 

 

 

 

[Harry Pristis]

Opinions are commonplace, non-remanie.  I would prefer to see your evidence that serrations wear or don't wear, in vivo.

[Troodon]

Here are a few examples with closeups of one complete edge with three pictures

Transition Tooth 1

\\

 

Edge closeups - no wear evident on any of the edges typical all teeth.

Nearest to root

 

Midline

 

Tip

 

 

Transition Tooth 2

 

Transition Tooth 3

 

Transition tooth 4 No serrations visible different tooth than one previously posted

 

 

Closeup of edge - No wear evident - crisp edge 

 

[Harry Pristis]

5 hours ago, Harry Pristis said:

But, possible tooth wear is only incidental to my speculation about positional differences and ontogenetic morphological changes.

 

Good work, Troodon!  How confident are you that that last tooth is Paleocarcharodon?  It looks Otodus-like in the image.   Do you have any thoughts that you can share about the other speculation about positional significance and ontogenetic change?

[Troodon]

I'm not sure I can add anything based on scientific evidence other than personal observations.  I have never seen any study about transitional Paleocarcharodon teeth possibly because the sampling size would be quite small and the stratigraphic information is unknown.   At the Tucson show I typically go through dozens of teeth trying to find transitional forms in a fruitless endeavor so they are not common.  I know that the dealers have not sorted their inventory so there is no bias. Morocco also appears to be the only locality that this form has been observed but that may be just because of sampling size or it may be geographic . 

 

  The morphology of the transitional teeth in my collection even those that have no serrations are identical to those that have standard serrations whether they are anterior or lateral.    The teeth appear to be fully formed so they are not from unerupted files.  They are definitely not otodus.   The serrations are typical what you read in the paper that described Carcharodon hubbelli :  Basal serrations are larger than the other serrations on the edges.   So it appears to be valid form of tooth.

 

So  the question is are theses teeth an intermediate form of Palaeocarcharodon orientalis or just an occurance that is present in some jaws and not a different species?   

[Harry Pristis]

Thank you, Troodon. 

 

There is collecting bias for large or unusual teeth . . . I saw it in a village in Morocco and I've seen it in Tucson.  The first source of collecting bias is the field collectors, some as young as eight or nine.  This is commercial collecting for them, and they know which teeth are more valuable.  The second source is the broker who buys from the collectors and sorts the teeth by size.  The third source is the dealer who buys teeth from the broker.  The dealer may travel to shows himself, or he may have someone who travels for him.  The final bias is introduced by the buyers at the shows who have gone through the accumulation of teeth before you got there.

 

So, what do you think of the ontogenetic morphological conjecture?  Do you have teeth from smaller Paleocarcharodon in your collection?

[Troodon]

I don't see a sorting bias at tucson because I'm "always" the first one in the key places.  It's an advantage I've used for years living in the area.  How I find the better material.   When I hit the moroccan tents most dealers are clueless about this form.  Cannot comment what happens in Morocco but this appears to be an obscure feature to most.

I cannot really comment on ontogenetic changes simply because of small sampling sizes and all my teeth are large and nothing that I see says it plays a part.  I have a few smaller teeth in my collections and they look a normal tooth.  I see David Ward at the show in Tucson and keep forgetting to get his opinion on these teeth.  

[doushantuo]

for those who like their classics: SIMBIRSK

plates 20-22 feature the vertebrate teeth

The plates in this one are awesome,BTW

NB:13 Mb PLUS:mollusca,echinodermata,etc

The shark in question is in here,of course

[Harry Pristis]

50 minutes ago, Troodon said:

all my teeth are large and nothing that I see says it plays a part.  I have a few smaller teeth in my collections and they look a normal tooth.

 

Thanks, Troodon.  Nice to live in Tucson, particularly in the winter!  How about showing us your smaller Paleocarcharodon teeth?

[Troodon]

Just took a quick phone picture of my smallest 3, heights around 1 inch.

 

[Harry Pristis]

Thanks, Troodon. 

 

Sooo . . . the smaller teeth we've seen here all have coarse serrations, while large teeth we've seen have fine or no serrations.  It's not dispositive one way or another, but the evidence certainly doesn't preclude ontogenetic change in the teeth of individual sharks. Anyone have smaller teeth with fine serrations?

[britishcanuk]

1 hour ago, Harry Pristis said:

Thanks, Troodon. 

 

Sooo . . . the smaller teeth we've seen here all have coarse serrations, while large teeth we've seen have fine or no serrations.  It's not dispositive one way or another, but the evidence certainly doesn't preclude ontogenetic change in the teeth of individual sharks. Anyone have smaller teeth with fine serrations?

Here's one I found online, it is 1 11/16" 

 

At this link

http://www.fossilsonline.com/index.php?main_page=product_info&products_id=939

[Harry Pristis]

1 hour ago, britishcanuk said:

Here's one I found online, it is 1 11/16" 

At this link

http://www.fossilsonline.com/index.php?main_page=product_info&products_id=939

 

Thanks, britishcanuk.  I'd say this fits the pattern for larger teeth.  I'm glad to see a lateral tooth.

[Sélacien34]

Hello everyone, what do you think about this one ?

 

3,9 cm - Oued Zem Kourigba Maroc

[Troodon]

Paleocarcharodon crowns are fairly compressed and do not see it in your specimen.  So I would lean against it being one.