Finally ... a discussion of fossil sharks from Morocco and transitional teeth.

[non-remanié]

Coco,

Sorry, the text is from "Les localités à mammifères des carrières de Grand Daoui,

bassin des Ouled Abdoun, Maroc, Yprésien : premier état des lieux" --- Gheerbrant et al 2003. But I think we already have it figured out. The mining industry usage makes direct translation a little confusing, but it seems that de facto with relation to geology it is just a different name for bed, layer or horizon. Does that sound right to you?

In the states our vinyl has grooves

-steve

Hi,

I don't know what is "sillon" in geology...

Here is the traditional definition of a "sillon" (here it is the field which was ploughed by a farmer)

We also listened to the music on the old vinyls records thanks to their "sillons".

In wich paper is this text from please ? Perhaps I have it and I could see to better understand and try to tell you what is it ?

Best regards

Coco

[siteseer]

I agree completely. I have Darteville & Casier 1943 from which it looks like Lamna schoutedeni was established, but I wish I could read the french text with the description From the plates, the left specimen sure looks like a good match with the wide enamel shoulders and reduced cusplets, but the right seems questionable.

I also noticed that something seems awry with your label, unless it is meant to be Sillon A2 rather than Couche IIa? Couche II is supposed to be within the Maastrichtian, possibly the last or second to last phosphate bed completely within it. I can't remember where, but I am sure I read that Sillon X is supposedly a very useful traceable marker bed for the end Maastrichtian phosphorite sequence. Either way, if Sillon X is the last Maastrichtian bed or spans the K/P transition, Couche II should still be completely within the Maastrichtian. All the stratigraphic charts, including Cappetta's do seem to have Sillon X as the end Maastrichtian bed as well.

-steve

Steve,

I think you are looking at Figure 4 of Noubhani and Cappetta (1997) which is a reconstructed stratigraphic column of a site at Youssoufia. At Khouribga, the column is more like the one for "Recette IV" in Figure 5 of the same article where Couche 2a is a Thanetian bed.

Yes, Sillon X has been described as containing the K/P boundary or being the youngest Maastrichtian layer.

I don't have Dartevelle and Casier (1943) but if you type out the text or send me the page(s), I can translate it.

[non-remanié]

Jess,

Yep I figured that out from reading in Gheerbrant "Couche III : Maastrichtien ; Couche II : Paléocène ; Cou -Ches I et 0, Sillons A et B : Yprésien" and then I found some other charts which confirm. I was originally using the one Noubhani & Cappetta chart that you scanned in, but I have been doing research as we go along and I had to find the answer to that “problem”. Its really a fairly confusing situation which I suspect could be partly to blame for the problematic ages of Moroccan fossils from the time that they came onto the market. There’s no formation names, just "sillon" and "couche" which are interchangeable depending on the local mining usage. I'm sure you know the general locality where your schoutedeni teeth came from, and thus which stratigraphic column to refer to, but perhaps you should add something like "local phosphate bed couche IIa" to your label just to avoid any possible future confusion, even though you surely have a good handle of the situation. It would have saved me a little confusion at least

-steve

Steve,

I think you are looking at Figure 4 of Noubhani and Cappetta (1997) which is a reconstructed stratigraphic column of a site at Youssoufia. At Khouribga, the column is more like the one for "Recette IV" in Figure 5 of the same article where Couche 2a is a Thanetian bed.

Yes, Sillon X has been described as containing the K/P boundary or being the youngest Maastrichtian layer.

I don't have Dartevelle and Casier (1943) but if you type out the text or send me the page(s), I can translate it.

Edited June 25, 2010 by toothpuller

[siteseer]

Jess,

Yep I figured that out from reading in Gheerbrant "Couche III : Maastrichtien ; Couche II : Paléocène ; Cou -Ches I et 0, Sillons A et B : Yprésien" and then I found some other charts which confirm. I was originally using the one Noubhani & Cappetta chart that you scanned in, but I have been doing research as we go along and I had to find the answer to that “problem”. Its really a fairly confusing situation which I suspect could be partly to blame for the problematic ages of Moroccan fossils from the time that they came onto the market. There’s no formation names, just "sillon" and "couche" which are interchangeable depending on the local mining usage. I'm sure you know the general locality where your schoutedeni teeth came from, and thus which stratigraphic column to refer to, but perhaps you should add something like "local phosphate bed couche IIa" to your label just to avoid any possible future confusion, even though you surely have a good handle of the situation. It would have saved me a little confusion at least

-steve

Steve,

Actually, I was confused yesterday myself when I realized that Couche II at one site was not the Couche II of another site. I didn't notice that before because I don't have a whole lot of teeth with the more exact locality info. It appears geologists have a handle on the stratigraphy but they still use the terminology of the mining companies? I know that the phosphate deposits of the area are just isolated pockets resulting from a few tens of millions years of erosion that have weathered away a once-immense phosphatic expanse that stretched from Morocco across North Africa and into the Middle East.

Yeah, couches don't seem to be thinner or thicker than sillons - no distinction I see yet - but I don't think that has anything to do with the lack of labeling of fossils at shows. I've seen how they're packed. Small teeth appear to be poured into boxes with the larger or recognized collector teeth better wrapped. It's just easier to dump it all into one box especially if it's all already mixed together in a spoil pile. I'm sure some of the Otodus are from the Thanetian beds but most are probably Ypresian, especially the larger ones, although some of the larger ones could be Late Paleocene as evidenced by the large specimens shown in another thread (Aquia Fm finds).

On a smaller scale you can find Middle Miocene, Early Pliocene, and Pleistocene fossils at the Lee Creek Mine in North Carolina. Like Morocco, you can sort out some fossils as being one of those ages, but some could be one of two of them.

[siteseer]

Here are some teeth to look at - Cretalamna appendiculata across time with over thirty million years in between:

First tooth:

Cretalamna appendiculata

Late Paleocene

Aquia Formation

Piscataway Member

Liverpool Point, Maryland

Second tooth:

Cretalamna appendiculata

Late Cretaceous

Britton Formation

Dallas, Texas

Third and fourth teeth:

Cretalamna appendiculata (lower teeth)

Late Cretaceous

Del Rio Clay

Lake Waco, Texas

(slightly older than the second tooth)

Edited June 25, 2010 by siteseer

[siteseer]

Here is one of those oddball teeth from Morocco without cusplets and a rather well-developed lingual protuberance. I cannot legitimately assign an age or name to it because it had no info with it though it is possibly an early Parotodus relative from the Early Eocene. It could be from the Paleocene but it bears no resemblance to Cretalamna but appears to be a weird Otodus.

[siteseer]

Here is a tooth that has been identified as an early species of Parotodus:

Parotodus mangyshlakensis

Middle Eocene

Bartonian - Upper Shorym

Bajurbas, Mangyshlak, west Kazakhstan

[siteseer]

Otodus obliquus - upper tooth:

Late Paleocene

Aquia Fm.

Piscataway Member

Wades Bay, Charles County, Maryland

[non-remanié]

I always have wondered about the fossil collecting in Morocco. In my mind (wild dreams) there were large spoil piles and pits similar to Aurora where surface collecting partially mixed the fossils of different ages, but I also have heard stories about wide-scale digging into specific bone-bed horizons. I guess it is likely a mixture of these processes. I was just envisioning a scenario where a local fossil dealer in a small town/city is asked by a foreign buyer where his supply of fossils comes from, and many of the local dealers potentially being associated with one geographical area they may answer the question as something like "couche 2", and either person may not fully realize the importance of knowing more than just "couche 2" in their dealings. I was just throwing the idea out there.

Steve,

Actually, I was confused yesterday myself when I realized that Couche II at one site was not the Couche II of another site. I didn't notice that before because I don't have a whole lot of teeth with the more exact locality info. It appears geologists have a handle on the stratigraphy but they still use the terminology of the mining companies? I know that the phosphate deposits of the area are just isolated pockets resulting from a few tens of millions years of erosion that have weathered away a once-immense phosphatic expanse that stretched from Morocco across North Africa and into the Middle East.

Yeah, couches don't seem to be thinner or thicker than sillons - no distinction I see yet - but I don't think that has anything to do with the lack of labeling of fossils at shows. I've seen how they're packed. Small teeth appear to be poured into boxes with the larger or recognized collector teeth better wrapped. It's just easier to dump it all into one box especially if it's all already mixed together in a spoil pile. I'm sure some of the Otodus are from the Thanetian beds but most are probably Ypresian, especially the larger ones, although some of the larger ones could be Late Paleocene as evidenced by the large specimens shown in another thread (Aquia Fm finds).

On a smaller scale you can find Middle Miocene, Early Pliocene, and Pleistocene fossils at the Lee Creek Mine in North Carolina. Like Morocco, you can sort out some fossils as being one of those ages, but some could be one of two of them.

[non-remanié]

Jess,

Could you scan in Arambourg's Cretalamna appendiculata plates? Darteville & Casier's C. appendiculata look exactly like most of the "small Otodus" from Md. The easier to differentiate Cretalamana variations in D&C look to match the Moroccan teeth well, but he doesn't have anything that looks like a more typical C. appendiculata (of any age) from the US. I'm just wondering if its the same in Arambourg.

-steve

[siteseer]

Jess,

Could you scan in Arambourg's Cretalamna appendiculata plates? Darteville & Casier's C. appendiculata look exactly like most of the "small Otodus" from Md. The easier to differentiate Cretalamana variations in D&C look to match the Moroccan teeth well, but he doesn't have anything that looks like a more typical C. appendiculata (of any age) from the US. I'm just wondering if its the same in Arambourg.

-steve

Steve,

I have some work tomorrow but should be able to do the scan.

That reminds me of an article you might already know about:

Shimada, K. 2007.

Skeletal and dental anatomy of lamniform shark, Cretalamna appendiculata, from Upper Cretaceous Niobrara Chalk of Kansas.

Journal of Vertebrate Paleontology 27 (3): 584-602.

I have a photocopy of it if you don't have it (don't think I have the PDF but will look).

Jess

[siteseer]

Jess,

Could you scan in Arambourg's Cretalamna appendiculata plates? Darteville & Casier's C. appendiculata look exactly like most of the "small Otodus" from Md. The easier to differentiate Cretalamana variations in D&C look to match the Moroccan teeth well, but he doesn't have anything that looks like a more typical C. appendiculata (of any age) from the US. I'm just wondering if its the same in Arambourg.

-steve

Steve,

Here's the scan of Plate XIV with translations of the captions (translators comments within brackets []):

Figures 1 - 11 - Montien [old name for the Early Paleocene] of the Louis Gentil site - Upper left jaw series in order: 1, 2, 1st and 2nd files; 3, intermediate (3rd anterior according to some authors); 4 - 11, laterals - labial and lingual views, profile views.

Figures 12 - 18 - Montian of the Louis Gentil site - Lower right jaw series in order: 12 - 14, 1st and 3rd files; 15 - 18, laterals - labial and lingual views, profiles.

Figures 19-24 - Maastrichtian of the Ouled Abdoun - 19, 2nd upper left file; 20, 21, upper right laterals; 22, 1st lower right anterior file; 23, 24, lower laterals - labial and lingual views, profiles.

All the figures of this plate are actual size [however the photocopy I have might be of a slightly different size so the scan is definitely not of the same original print size - maybe 25-30% smaller]

Jess

Edited June 30, 2010 by siteseer

[non-remanié]

Thanks Jess. These look like much more familiar appendiculata as compared to many of Darteville & Casier's. Its a shame those old texts didn't have scales, I have encountered that problem a few times already, but its not a big deal. I do have the Shimada PDF.

-steve

Steve,

Here's the scan of Plate XIV with translations of the captions (translators comments within brackets []):

Figures 1 - 11 - Montien [old name for the Early Paleocene] of the Louis Gentil site - Upper left jaw series in order: 1, 2, 1st and 2nd files; 3, intermediate (3rd anterior according to some authors); 4 - 11, laterals - labial and lingual views, profile views.

Figures 12 - 18 - Montian of the Louis Gentil site - Lower right jaw series in order: 12 - 14, 1st and 3rd files; 15 - 18, laterals - labial and lingual views, profiles.

Figures 19-24 - Maastrichtian of the Ouled Abdoun - 19, 2nd upper left file; 20, 21, upper right laterals; 22, 1st lower right anterior file; 23, 24, lower laterals - labial and lingual views, profiles.

All the figures of this plate are actual size [however the photocopy I have might be of a slightly different size so the scan is definitely not of the same original print size - maybe 25-30% smaller]

Jess

[siteseer]

Steve,

There is a publication I've been meaning to mention. I had forgotten about it and then looked for it in my stuff and couldn't find it. Then, I found it while flipping through files for something else. Do you have this:

Case, G.R. 1974.

Fossil collecting in Morocco, North Africa. Earth Science. January/February 1974.

The volume and issue numbers don't show on the photocopies I have but you should be able to find it with that info if you don't have it. It does provide more background. I think the French word "recette" is what Case calls a "trace-pit," a trench or a cut. I've heard "cut" used as a term in the Florida phosphate mines but thought that was what they called the spot they were working - not like a test pit or trench to confirm the stratigraphy at a certain site.

My print is faded in spots so I will see if I can copy myself an upgrade at the USGS.

[xenacanthus]

wow thats a great tooth i wish i had at least one of those but i live where there are no shark teeth

[Harry Pristis]

Here is one of those oddball teeth from Morocco without cusplets and a rather well-developed lingual protuberance. I cannot legitimately assign an age or name to it because it had no info with it though it is possibly an early Parotodus relative from the Early Eocene. It could be from the Paleocene but it bears no resemblance to Cretalamna but appears to be a weird Otodus.

[Originally posted to a different thread, but this seems to be the best place for this information.]

I spent some time reading the Elasmo.com account of Parotodus (I don't know how I've missed this entry from June 2008, but I did!)

I now believe that these Moroccan "Parotodus-like" teeth are:

Family OTODONTIDAE

Paratodus pavlovi (Menner) 1928

I BELIEVE this is the best way to get a handle on this murky taxonomy which may never become any clearer.

For those who are interested, here are some excerpts from Jim Bourdon's article on Elasmo:

Menner (1928: 337) described the new species Otodus pavlovi for teeth from the Ypresian (Early Eocene) of western Kazakhstan. The teeth were briefly described as small, bearing lateral cusplets and a well-developed root. Zhelezko & Kozlov (1999:157) moved pavlovi to Parotodus. Collectors have attributed similar teeth from the London Clay to this taxon, however this has never been published.

Zhelezko & Kozlov (1999b:156-57) erected the species Parotodus mangyshlakensis for cuspleted Parotodus-like teeth from the Middle/Late Eocene Schorym Formation in Mangyshlak, Kazakhstan. They described them as larger and with a broader, more massive, crown than P. pavlovi and less so than P. benedeni; they considered it a transitional form between the two.

Thoughts on those Eocene teeth

One's take on the genus of the Eocene teeth is largely influenced by an underlying boolean decision of the P. benedeni tooth-design -- otodontid or not. If thinking of benedeni to be the former, the Eocene examples make an excellent transitional form -- combining robust otodontid-like roots (sensu Cretalamna & Otodus) and cusplets, but with a thick (D-shaped) cusp.

However, if one rejects the notion of P. benedeni being an otodontid, then the lack of cusplets, thick cusp and more importantly root and dentition designs serve as excellent evidence to separate the P. benedeni from that Eocene design. Personally, I tend to side with Siverson & Lindgren (2005) and consider the Eocene teeth otodontid and unrelated to P. benedeni. Unlike Siverson and based on dentition design, I don't consider P. benedeni a cardabiodontid, but more likely an alopiid as suggested by Herman (1979)13.

Zhelezko, V., and Kozlov, V., 1999b. Elasmobranchii and Palaeogene biostratigraphy of Transurals and Central Asia. Materials on stratigraphy and Palaeontology of the Urals Vol. 3. Russian Academy of Sciences Urals Branch Uralian Regional Interdepartment Stratigraphical Comissian, Ekkaterinburg. 324 pp, 61pls.

[surfergirlatx]

Great find! Thanks for sharing!

[siteseer]

Harry,

I wanted to get to your original question especially after finding one of these teeth at the Tucson show (one of them). Here is an apparent upper lateral Palaeocarcharodon from the time when it was unserrate to weakly-serrated. Unfortunately, the tooth had no locality data but this form has come out of Danian (Early Paleocene) beds and the color matches some Danian teeth I've seen (circumstantial evidence, I know).

Anyway, I have wondered what the ancestor was as well. No tooth form is a slam dunk match. It has been assumed to be Cretalamna and it could be but no known species of that genus looks like a Palaeocarcharodon without serrations. I have considered some variation of C. maroccana.

Palaeocarcharodon often has a flatter (labiolingually compressed) crown and the crown can have prominent folds at the base of the labial face. It is also rather large even in the Danian. It makes me think there is a Cretaceous shark also of the Tethys region (North Africa, Middle East) we haven't seen yet. Another possibility is that right after the K/T extinction there was an unchecked burst of speciation spurred by lack of competition (nearly all large marine vertebrates other than crocodiles and some deepwater sharks died out) among sharks. Some Danian species seem to have appeared out of nowhere but it's just that their immediate ancestors lived in a small unaffected/relatively-unaffected area where there was little/no sedimentation (currents transported and abraded them to bits) or perhaps the deposit remains yet-to-be-discovered or the teeth are just very rare where people are already digging. Stingrays are rare in the Cretaceous but they pop up in many areas and are more abundant in the Paleocene.

Jess

Cool tooth, Kevin!

You say it's a transitional form, and it may well be. What is the transition? That is, what species is it that is transitioning to P. orientalis?

I glanced at Elasmo.com and Kent's book, but didn't find the answer to this question.

------Harry Pristis

Edited June 24, 2012 by siteseer

[Harry Pristis]

Harry,

I wanted to get to your original question especially after finding one of these teeth at the Tucson show (one of them). Here is an apparent upper lateral Palaeocarcharodon from the time when it was unserrate to weakly-serrated. Unfortunately, the tooth had no locality data but this form has come out of Danian (Early Paleocene) beds and the color matches some Danian teeth I've seen (circumstantial evidence, I know).

Anyway, I have wondered what the ancestor was as well. No tooth form is a slam dunk match. It has been assumed to be Cretalamna and it could be but no known species of that genus looks like a Palaeocarcharodon without serrations. I have considered some variation of C. maroccana.

Palaeocarcharodon often has a flatter (labiolingually compressed) crown and the crown can have prominent folds at the base of the labial face. It is also rather large even in the Danian. It makes me think there is a Cretaceous shark also of the Tethys region (North Africa, Middle East) we haven't seen yet. Another possibility is that right after the K/T extinction there was an unchecked burst of speciation spurred by lack of competition (nearly all large marine vertebrates other than crocodiles and some deepwater sharks died out) among sharks. Some Danian species seem to have appeared out of nowhere but it's just that their immediate ancestors lived in a small unaffected/relatively-unaffected area where there was little/no sedimentation (currents transported and abraded them to bits) or perhaps the deposit remains yet-to-be-discovered or the teeth are just very rare where people are already digging. Stingrays are rare in the Cretaceous but they pop up in many areas and are more abundant in the Paleocene.

Jess

What an interesting tooth, Jess! I'm not at all certain that I would have recognized it as Palaeocarcharodon, had someone put the tooth into my hand. None of the P. orientalis (Morocco) in my drawer has the prominent enamel folding, and all have coarse serrations.

Sooo . . . The mystery persists. I like the speculation about the bloom of new species after the K/T extinction.

[siteseer]

Harry,

I have a small upper lateral tooth also bearing prominent and high enameloid folds. I don't know if that is a character of early representatives of the genus or if it means the folds are present but less exaggerated in the ancestral form. Cretodus had folds but they were very short and it appears to have become extinct well before the end of the Cretaceous (depending on where you place the species, borodini). I have other teeth without the folds too. I have an odd lower anterior too - serrations irregular even for a Palaeocarcharodon.

I looked at my other teeth and they all bear crowns that are perceptibly flatter than those of other genera in the same size range (though perhaps the same level of flatness seen in Isurus retroflexus).

I thought about cleaning the tooth and saving the matrix to see if the bed could be determined but there's never a Moroccan phosphate bed matrix expert around when you need one.

I found the tooth on the table of a Moroccan dealer during the last hour of the last day of the show. The tooth isn't perfect, but with all the shark collectors going through, you would think someone would have picked it out from the crowd on the first weekend (priced at only $4). That's the kind of tooth collectors are looking for when they go through flats.

Jess

What an interesting tooth, Jess! I'm not at all certain that I would have recognized it as Palaeocarcharodon, had someone put the tooth into my hand. None of the P. orientalis (Morocco) in my drawer has the prominent enamel folding, and all have coarse serrations.

Sooo . . . The mystery persists. I like the speculation about the bloom of new species after the K/T extinction.

[primativesloth]

Some very nice tooths here.

[Sélacien34]

Harry,

Here are the two teeth I received with the label Cretalamna schoutedeni:

Late Paleocene (Thanetian)

Couche 2a

Khouribga, Morocco

Jess,

Yep I figured that out from reading in Gheerbrant "Couche III : Maastrichtien ; Couche II : Paléocène ; Cou -Ches I et 0, Sillons A et B : Yprésien" and then I found some other charts which confirm. I was originally using the one Noubhani & Cappetta chart that you scanned in, but I have been doing research as we go along and I had to find the answer to that “problem”. Its really a fairly confusing situation which I suspect could be partly to blame for the problematic ages of Moroccan fossils from the time that they came onto the market. There’s no formation names, just "sillon" and "couche" which are interchangeable depending on the local mining usage. I'm sure you know the general locality where your schoutedeni teeth came from, and thus which stratigraphic column to refer to, but perhaps you should add something like "local phosphate bed couche IIa" to your label just to avoid any possible future confusion, even though you surely have a good handle of the situation. It would have saved me a little confusion at least

-steve

schoutedeni1.jpg

schoutedeni2.jpg

schoutedeni3.jpg

Hi, i dig this topic to thank Siteseer and Non-remanié because I bought some Cretalamna a few years ago, among whom were these four teeth, which did not correspond to the specie C. appendiculata. Your conversation allowed me to identify these teeth as C. schoutedeni. But i'm a little lost in the middle of your layers and your sillons because I do not have this document from Darteville and Casier, what would be the exact period in which this species lived?

On the document below C. (isurus?) schoutedeni is presented as the ancestor of Mr. praecursor, this assumption is it relevant?

Edited May 13, 2014 by Sélacien34

[siteseer]

Selacien34,

Every time I check a post here, I feel like I have to read the whole thread to get back into the flow of the conversation. I did read through it again for your post.

Those are nice teeth - nice show finds. There is not a lot of information on C. schoutedeni but it appears to be restricted to the Late Paleocene. I am not certain but I do not think schoutedeni was the direct ancestor of I. praecursor as neither seems to have been present in the Ypresian. The earliest praecursor teeth I've seen have been Lutetian-age (Bracklesham Bay, UK and Harleyville, South Carolina). I have wondered if some form of (or close to) Isurolamna was an intermediate between Cretalamna and Isurus especially since Isurolamna is common in many such deposits and could have engendered some rare transitional form.

Jess

Hi, i dig this topic to thank Siteseer and Non-remanié because I bought some Cretalamna a few years ago, among whom were these four teeth, which did not correspond to the specie C. appendiculata. Your conversation allowed me to identify these teeth as C. schoutedeni. But i'm a little lost in the middle of your layers and your sillons because I do not have this document from Darteville and Casier, what would be the exact period in which this species lived?
On the document below C. (isurus?) schoutedeni is presented as the ancestor of Mr. praecursor, this assumption is it relevant?

C. schoutedeni.JPGLIGNEE LAMNIFORMES - (2).jpg

[Sélacien34]

Hi Jess,

i have found the work from Dartevelle and Casier since my last post and an other publication from J. herman who describes teeth from the Thanetian and from the Ypresian, beginning of Eocene of Sidi Daoui, Maroc. So just before the Lutetian age.

Under these conditions, this species might be the link with Mr. praecursor, don't you think?

The latest teeth described by J. Herman present different characters from those described by Dartevelle, from the Cretaceous of Congo.

Discussion : Teeth with massive root , narrow crown, tapered at the top and rapidly widening when approach the root ending in blades enameled, never recovering to form draft denticles ( as they do in Lamna schoutedeni Dartevelle and Records, here understood as the premutation ) .
Instead, the enamel side blades form an obtuse angle with the crown and will diminishing towards the ends of the root .
The inner surface of the root sometimes has a groove more or less clear at the top which opens a foramen , most often it has only the single foramen .
We still have too few specimens of this species to a reconstruction of the teeth .
I see Lamna schoutedeni from Dartevelle and Casier as the ancestral form of oxyrhina schoutedeni , the reason why this specific name is assigned.
Recall that L. schoutedeni is known from " Montien " (Danian) of Lândana's cliffs .
The age of L. Schoutedeni is consistent with its most advanced stage of development .

Here the specimens figured by the author (four teeth from thanetan) considered as the holotype, if I'm not mistaken, and those from Dartevelle and Casier.

Strangly, Because I think my teeth are from Morocco, they correspond to the teeth from the Cretaceous of Congo but they are probably older and from an other site. Apparently, these 2 forms result one from the other

Here you can get the publication :

http://www.google.fr/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CDAQFjAB&url=http%3A%2F%2Fwww.vliz.be%2Fimisdocs%2Fpublications%2F135414.pdf&ei=NfWNU5adE8md0wXI5oBQ&usg=AFQjCNG88X3NS7q_92Zcn-_sTqIXgV09Xw&bvm=bv.68191837,d.d2k

Other more recent illustrations of the first and the second form :

Edited June 4, 2014 by Sélacien34

[siteseer]

Selacien34,

Thanks for the information and figures. FF member non-remanie and I spent Sunday afternoon trading emails. He informed me of the presence of Macrorhizodus nolfi in the Ypresian of Kazakhstan and it is also figured in the book, "London Clay Fossil of Kent and Essex. It is a very rare species. I should have remembered M. nolfi. I can't believe I forgot about it.

Jess

Hi Jess,

i have found the work from Dartevelle and Casier since my last post and an other publication from J. herman who describes teeth from the Thanetian and from the Ypresian, beginning of Eocene of Sidi Daoui, Maroc. So just before the Lutetian age.

Under these conditions, this species might be the link with Mr. praecursor, don't you think?

The latest teeth described by J. Herman present different characters from those described by Dartevelle, from the Cretaceous of Congo.

Discussion : Teeth with massive root , narrow crown, tapered at the top and rapidly widening when approach the root ending in blades enameled, never recovering to form draft denticles ( as they do in Lamna schoutedeni Dartevelle and Records, here understood as the premutation ) .
Instead, the enamel side blades form an obtuse angle with the crown and will diminishing towards the ends of the root .
The inner surface of the root sometimes has a groove more or less clear at the top which opens a foramen , most often it has only the single foramen .
We still have too few specimens of this species to a reconstruction of the teeth .
I see Lamna schoutedeni from Dartevelle and Casier as the ancestral form of oxyrhina schoutedeni , the reason why this specific name is assigned.
Recall that L. schoutedeni is known from " Montien " (Danian) of Lândana's cliffs .
The age of L. Schoutedeni is consistent with its most advanced stage of development .

Here the specimens figured by the author (four teeth from thanetan) considered as the holotype, if I'm not mistaken, and those from Dartevelle and Casier.

schout.PNG 1- C. schoutedeni (Dartevelle)--.PNG

Strangly, Because I think my teeth are from Morocco, they correspond to the teeth from the Cretaceous of Congo but they are probably older and from an other site. Apparently, these 2 forms result one from the other

Here you can get the publication :

http://www.google.fr/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CDAQFjAB&url=http%3A%2F%2Fwww.vliz.be%2Fimisdocs%2Fpublications%2F135414.pdf&ei=NfWNU5adE8md0wXI5oBQ&usg=AFQjCNG88X3NS7q_92Zcn-_sTqIXgV09Xw&bvm=bv.68191837,d.d2k

Other more recent illustrations of the first and the second form :

Cretolamna_schoutedeni.jpgisurus_shoutedeni.jpg