Jump to content

Recommended Posts

Northern Sharks

Santa came early here in the north country. I've been after one of these for a while and I finally got one in the mail today. It's an early, transitional form, Palaeocarcharodon orientalis. Very coarse serrations near the root fading to almost smooth at the tip. One root tip was glued back on as these teeth are very prone to damage, but I can ignore that because it's almost 2 inches long, and they don't get much bigger than that.

post-77-1198109557_thumb.jpg

Share this post


Link to post
Share on other sites
Gatorman

Very nice tooth. :Thumbs-up:

Share this post


Link to post
Share on other sites
Harry Pristis
Santa came early here in the north country. I've been after one of these for a while and I finally got one in the mail today. It's an early, transitional form, Palaeocarcharodon orientalis. Very coarse serrations near the root fading to almost smooth at the tip. One root tip was glued back on as these teeth are very prone to damage, but I can ignore that because it's almost 2 inches long, and they don't get much bigger than that.

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

Share this post


Link to post
Share on other sites
Northern Sharks

Harry:Here's a link to a site with lots of useful info. http://megmawl.com/relatives.html. The chart at the end of this proposes that P. orientalis is a descendant of C. Appendiculata. There is a similar family tree on pg.132 of Joe Cocke's book, Fossil Shark Teeth of the World. Mark Renz also agrees with this theory in his Megalodon: Hunting the Hunter.

Share this post


Link to post
Share on other sites
Harry Pristis
Harry:Here's a link to a site with lots of useful info.http://megmawl.com/relatives.html. The chart at the end of this proposes that P. orientalis is a descendant of C. Appendiculata. There is a similar family tree on pg.132 of Joe Cocke's book, Fossil Shark Teeth of the World. Mark Renz also agrees with this theory in his Megalodon: Hunting the Hunter.

Thanks for the direction. I didn't think to look at Mark Renz's book, but he does provide some useful photos. I don't have Joe Cocke's book, and I don't know his name -- is he a shark researcher or a compiler of information?

I helped edit Mark's book, but not this chapter. I note his unorthodox spelling of "Cretalamna" instead of the expected "Cretolamna." Mark seems also to have a variance in the dating of the Danian Age which the GSA timescale has at 65 to 61 Ma.

There is an explanation of the "Cretalamna: vs "Cretolamna" spelling discrepancy at ELASMO.COM . You'll have to navigate the tool-bars -->GENERA -->PALEOGENE -->LAMNIFORMES -->CRETALAMNA (scroll to the bottom "notes.")

I believe it is overstating the matter to say that Mark agrees with one theory or the other. What he does is summarize two competing theories. One theory specifically identifies P. orientalis as a descendent of Cretolamna appendiculata (the Cretolamna-->Carcharodon megalodon lineage).

The other theory holds that P. orientalis is a failed experiment within the Otodus-->Carcharocles lineage; that is, not closely related to Cretolamna. This is another, earlier manifestation of the megatooth shark hypothoses.

Sooo, Kevin, you buy into which one of these theories??? If you believe that P. orientalis descended from Cretolamna, then aren't you buying into the Carcharodon megalodon hypothesis? I thought you were a Carcharocles kinda' guy.

Personally, I don't have any qualms about accepting the idea of a "failed experiment" in the Carcharocles ancestry. What do you think?

--------Harry Pristis

Share this post


Link to post
Share on other sites
Northern Sharks

The way I've been understanding has early Cretolamna evolving into 3 branches: the Otodus lineage, the makos with I. praecursor and the dead end Palaeocarcharodon. Joe Cocke is a collector and worked in the Natural History Museum of L.A. County for 33 yrs as taken from the back of his book.

Share this post


Link to post
Share on other sites
ashcraft
The other theory holds that P. orientalis is a failed experiment within the Otodus-->Carcharocles lineage; that is, not closely related to Cretolamna. This is another, earlier manifestation of the megatooth shark hypothoses.

Sooo, Kevin, you buy into which one of these theories??? If you believe that P. orientalis descended from Cretolamna, then aren't you buying into the Carcharodon megalodon hypothesis? I thought you were a Carcharocles kinda' guy.

Personally, I don't have any qualms about accepting the idea of a "failed experiment" in the Carcharocles ancestry. What do you think?

--------Harry Pristis[/size][/font]

I never much like the term "failed experiment", with sharks or anything else, dealing with evolution (not that I am being critical of Harry, it has become a term in the vernacular). Experiment implies purpose, when of course there wasn't any. Failed is in the eyes of the beholder. All species will go extinct, the length of time they exist is dependent on environmental factors and chance. A genus is no different. A genus arises from a single species, and then tries to speciate by adapting to new environments or through other forms of selection.

Just wanted to post a reply and see how it worked.........

Brent Ashcraft

Share this post


Link to post
Share on other sites
Harry Pristis
The way I've been understanding has early Cretolamna evolving into 3 branches: the Otodus lineage, the makos with I. praecursor and the dead end Palaeocarcharodon. Joe Cocke is a collector and worked in the Natural History Museum of L.A. County for 33 yrs as taken from the back of his book.

Sooo, you believe that Cretolamna appendiculata is the stem megatooth shark. Could be. That is a solution to the dilemma I posed in my earlier post.

All megatooth sharks arose from the Cretaceous Cretolamna appendiculata. Sounds easy enough. We know that Cretolamna survived the K-T extinction. We know that Cretolamna was a flexible group, world-wide in distribution, having a number of species and even subspecies. Welton & Farish note that C. appendiculata teeth increase in size from older to younger sediments in the Cretaceous. Can we rely on this evolutionary solution? Maybe.

Has anyone gone on record as supporting this evolutionary scheme?

C. appendiculata

\__Otodontidae

\__Issuridae

\__Paleocarcharodon

I have been out of touch for a few years, and what I read is that the taxonomy of these Cretaceous sharks is still murky. The relationships to Paleocene (and later) sharks is still being sorted out, as I read it. I haven't had a chance to look at megmawl.com, but I will. I don't have the answer to this interesting problem.

-------Harry Pristis

Share this post


Link to post
Share on other sites
Northern Sharks
Sooo, you believe that Cretolamna appendiculata is the stem megatooth shark. Could be. That is a solution to the dilemma I posed in my earlier post.

All megatooth sharks arose from the Cretaceous Cretolamna appendiculata. Sounds easy enough. We know that Cretolamna survived the K-T extinction. We know that Cretolamna was a flexible group, world-wide in distribution, having a number of species and even subspecies. Welton & Farish note that C. appendiculata teeth increase in size from older to younger sediments in the Cretaceous. Can we rely on this evolutionary solution? Maybe.

Has anyone gone on record as supporting this evolutionary scheme?

C. appendiculata

\__Otodontidae

\__Issuridae

\__Paleocarcharodon

I have been out of touch for a few years, and what I read is that the taxonomy of these Cretaceous sharks is still murky. The relationships to Paleocene (and later) sharks is still being sorted out, as I read it. I haven't had a chance to look at megmawl.com, but I will. I don't have the answer to this interesting problem.

-------Harry Pristis

http://www.elasmo.com/frameMe.html?file=he...topics-alt.html

I don't know if the link will work this time or not, but Bill Heim at Elasmo.com seems to be in favor of this family tree. Also, while Cretolamna looks like the forerunner of the giant white sharks, it may or may not be C. appediculata. One person states on eurolasmo.com that it could be C.gunsoni (Siverson, 1996) which I had never heard of. As you say Harry, it is murky. I'd love to have more time to search for things like this, but I have 3 young kids and my spare time is limited.

Share this post


Link to post
Share on other sites
Gatorman

I find this topic extremely interesting, and it seems the subject matter is up for debate I do hope that this conversation can continue on with more opinions added and more information also. I am pinning this topic for now.

Share this post


Link to post
Share on other sites
Harry Pristis
http://www.elasmo.com/frameMe.html?file=he...topics-alt.html

I don't know if the link will work this time or not, but Bill Heim at Elasmo.com seems to be in favor of this family tree. Also, while Cretolamna looks like the forerunner of the giant white sharks, it may or may not be C. appediculata. One person states on eurolasmo.com that it could be C.gunsoni (Siverson, 1996) which I had never heard of. As you say Harry, it is murky. I'd love to have more time to search for things like this, but I have 3 young kids and my spare time is limited.

That's great! I see now that Kent doesn't seem to doubt that Cretolamna appendiculata is the stem megatooth shark.

This thread has helped me focus on a bit of shark ancestry that has always seemed confusing and remote from my collecting experience here in Florida. If I were collecting shark teeth in Texas, I probably would know more about the systematics of Cretaceous teeth. Maybe Ontario is the place to be to get a balanced overview. Thanks for contributing.

-----Harry Pristis

Share this post


Link to post
Share on other sites
Harry Pristis
That's great! I see now that Kent doesn't seem to doubt that Cretolamna appendiculata is the stem megatooth shark.

<snip>

I think this is the "stem megatooth shark." Is this right, NS?

post-42-1198303439_thumb.jpg

Share this post


Link to post
Share on other sites
Guest Cris

I've got a couple of those from a trade I did with someone... I may just have to set up a display of all the different branches of Cretolamna appendiculata one day if I ever aquire enough of the specimens.

Share this post


Link to post
Share on other sites
Northern Sharks

Harry: That looks correct in my eyes. That tooth and the Cretolamna appendiculata maroccana teeth you posted are still unusual. Most Moroccan teeth are that typical tan/beige/orange type color. I sure don't see too many that dark. Nice finds.

Share this post


Link to post
Share on other sites
Harry Pristis
Harry: That looks correct in my eyes. That tooth and the Cretolamna appendiculata maroccana teeth you posted are still unusual. Most Moroccan teeth are that typical tan/beige/orange type color. I sure don't see too many that dark. Nice finds.

NS . . . All these teeth come out of a poorly-consolidated sandstone similar to the matrix from which the Moroccans extract dinosaur teeth (commonly the fish-eating Spinosaurus) and bone fragments. There is some matrix (sand grains) adhering to a few of these teeth. Perhaps a dino collector here knows the name of the formation.

Here is another group of teeth from that sandstone. See if I have the ID correct.

-------Harry Pristis

post-42-1198337355_thumb.jpg

Share this post


Link to post
Share on other sites
Northern Sharks

Harry: The one in the upper left is iffy. The base of the root looks more like Cretolamna than Serratolamna. The others all look correct but.....Serratolamna is late paleocene/early eocene, not cretaceous. If your age is correct, your ID needs to change.

Share this post


Link to post
Share on other sites
Harry Pristis
Harry: The one in the upper left is iffy. The base of the root looks more like Cretolamna than Serratolamna. The others all look correct but.....Serratolamna is late paleocene/early eocene, not cretaceous. If your age is correct, your ID needs to change.

Hmmmm! Here's what Kent says:

"During the late Cretaceous three genera of very similar mackerel sharks were prevalent in the Chesapeake Bay area; Cretodus, Cretolamna and Serratolamna. Although most successful during this period, a few species of the latter two genera survived well into the Early Paleogene."

Kent does say that Serratolamna aschersoni is known from the Early Eocene of Morocco, so K to Eocene is a huge disparity for the age of this group of teeth. I missed that. I'll have to rethink that group.

Here's another group of these teeth. I think these are Cretodus, a strictly cretaceous genus, according to Kent. What do you think?

-----Harry Pristis

post-42-1198340252_thumb.jpg

Share this post


Link to post
Share on other sites
Northern Sharks
Hmmmm! Here's what Kent says:

"During the late Cretaceous three genera of very similar mackerel sharks were prevalent in the Chesapeake Bay area; Cretodus, Cretolamna and Serratolamna. Although most successful during this period, a few species of the latter two genera survived well into the Early Paleogene."

Kent does say that Serratolamna aschersoni is known from the Early Eocene of Morocco, so K to Eocene is a huge disparity for the age of this group of teeth. I missed that. I'll have to rethink that group.

Here's another group of these teeth. I think these are Cretodus, a strictly cretaceous genus, according to Kent. What do you think?

-----Harry Pristis

Harry: Now I'm jealous :D That's a species I don't have yet. Assuming yours have rounded/damaged cusps, that looks right to me, but it seems the identification may have changed. Here's yet another link to elasmo.com

http://www.elasmo.com/frameMe.html?file=ge...genera-alt.html

Getting back to Serratolamna, the cretaceous species is S. serrata. S.aschersoni is strictly eocene. This is also in Kent's book (Fossil Sharks of the Chesapeake Bay Region- a great reference) on pg. 118/119.

Share this post


Link to post
Share on other sites
Harry Pristis
Harry: Now I'm jealous :D That's a species I don't have yet. Assuming yours have rounded/damaged cusps, that looks right to me, but it seems the identification may have changed. Here's yet another link to elasmo.com

http://www.elasmo.com/frameMe.html?file=ge...genera-alt.html

Getting back to Serratolamna, the cretaceous species is S. serrata. S.aschersoni is strictly eocene. This is also in Kent's book (Fossil Sharks of the Chesapeake Bay Region- a great reference) on pg. 118/119.

Thanks for the link. I don't have Siverson's paper, and I do have Kent's book, so I'll still think of these as "Cretodus." The cusplets seem natural on these two teeth -- not much of any stream-polish on any of these teeth. What are the odds that all four cusplets would be worn down in the same manner?

I believe that these teeth are all from channel-lag (probably) deposits in the Baharija Beds (Cenomanian, 93-99 Ma) of Morocco. These, I believe, are the deposits that produce the Onchopristis (sawfish) and Ceratodus (lungfish) teeth along with disarticulated dino material.

Now, here're the teeth from this group that I think are Serratolamna serrata using Kent's scheme. What do you think?

------Harry Pristis

post-42-1198349063_thumb.jpg

Share this post


Link to post
Share on other sites
Harry Pristis
I've got a couple of those from a trade I did with someone... I may just have to set up a display of all the different branches of Cretolamna appendiculata one day if I ever aquire enough of the specimens.

Show us your shark teeth, Cris. Did you get any collecting data?

I will put some images into my album after NS tells me what they are. They will be there for future reference. Help us out with this challenge with your pix.

--------Harry Pristis

Share this post


Link to post
Share on other sites
Northern Sharks
Thanks for the link. I don't have Siverson's paper, and I do have Kent's book, so I'll still think of these as "Cretodus." The cusplets seem natural on these two teeth -- not much of any stream-polish on any of these teeth. What are the odds that all four cusplets would be worn down in the same manner?

I believe that these teeth are all from channel-lag (probably) deposits in the Baharija Beds (Cenomanian, 93-99 Ma) of Morocco. These, I believe, are the deposits that produce the Onchopristis (sawfish) and Ceratodus (lungfish) teeth along with disarticulated dino material.

Now, here're the teeth from this group that I think are Serratolamna serrata using Kent's scheme. What do you think?

------Harry Pristis

My resources are getting a workout, but I'm having a ball with this. Tough to tell if the teeth are S. serrata or S. aschersoni. As I know, lateral S.serrata teeth have an uneven number of cusps on each side and the main crown is noticeably off-center. I have 3 S.aschersoni teeth, with 1,2 and 3 sets of side cusps respectively (still looking for my first S.serrata though). There is another species, S.gafsana I just found out about on elasmo.com. You may want to look into that as a possibility for some of your teeth. The biggest problem still is the age. The oldest S.serrata is Maastrichtian (65-71Ma) and that's a 30 million yr difference to what you're saying. Onchopristis and Ceratodus fit this time frame, but not Serratolamna. I guess it's time for me to ask you if you have any sources for your age.

Share this post


Link to post
Share on other sites
Northern Sharks
Show us your shark teeth, Cris. Did you get any collecting data?

I will put some images into my album after NS tells me what they are. They will be there for future reference. Help us out with this challenge with your pix.

--------Harry Pristis

I just read this post Harry. No pressure or anything :blush:

Share this post


Link to post
Share on other sites
Harry Pristis
My resources are getting a workout, but I'm having a ball with this. Tough to tell if the teeth are S. serrata or S. aschersoni. As I know, lateral S.serrata teeth have an uneven number of cusps on each side and the main crown is noticeably off-center. I have 3 S.aschersoni teeth, with 1,2 and 3 sets of side cusps respectively (still looking for my first S.serrata though). There is another species, S.gafsana I just found out about on elasmo.com. You may want to look into that as a possibility for some of your teeth. The biggest problem still is the age. The oldest S.serrata is Maastrichtian (65-71Ma) and that's a 30 million yr difference to what you're saying. Onchopristis and Ceratodus fit this time frame, but not Serratolamna. I guess it's time for me to ask you if you have any sources for your age.

Well, Cenomanian-age is just a guess. I do not have any collecting data on these teeth, so I'm hoping that the age can be deduced by the species present. These could be Maastrichtian as easily as Cenomanian, though I don't know of any significant Maastrichtian non-phosphate fossils from Morocco. But, that lack of knowledge is not definitive, just speculative.

This is a big problem with Moroccan fossils. The older paleontology papers are in French, for the most part. The diggers don't know any paleontology, and the brokers are just interested in accumulating and selling curios. (This is changing slowly, I think, but it is market-driven.) I've been to Erfoud and elsewhere, and I've seen it for myself.

Mostly, the average collector has to reconstruct as best he can some sort of paleontological framework for a Moroccan fossil. This is the reason that these teeth of mine have been sitting here in a zip-lock bag for years, and not in my drawer.

The teeth will have to tell the story. If Cenomanian is too early, so be it. I will have to read some more.

No pressure! LOL

------Harry Pristis

Share this post


Link to post
Share on other sites
Harry Pristis

Okay, these Moroccan teeth are not Cenomanian. I think I have them sorted out now, and I believe that they are Early Eocene (Ypresian). I will be changing the tags on my photos where necessary.

I still have two teeth that I am (more) uncertain about -- the two that appeared to be Cretodus arcuata in my original assessment. If Cretodus is a strictly Cretaceous genus, then they are probably something else. I realized that I have two Cretodus (Plicatolamna) arcuata teeth from New Jersey in my collection. The NJ teeth seem to be somewhat stream-polished, still I don't see a lot of resemblance.

I have considered the possibility that these Moroccan teeth represent Jaekelotodus sp which have a nutrient groove and reduced (though doubled) cusplets in the line-drawings in Kent.

What do you think?

----Harry Pristis

post-42-1198451007_thumb.jpg

post-42-1198451056_thumb.jpg

Share this post


Link to post
Share on other sites
Northern Sharks
Okay, these Moroccan teeth are not Cenomanian. I think I have them sorted out now, and I believe that they are Early Eocene (Ypresian). I will be changing the tags on my photos where necessary.

I still have two teeth that I am (more) uncertain about -- the two that appeared to be Cretodus arcuata in my original assessment. If Cretodus is a strictly Cretaceous genus, then they are probably something else. I realized that I have two Cretodus (Plicatolamna) arcuata teeth from New Jersey in my collection. The NJ teeth seem to be somewhat stream-polished, still I don't see a lot of resemblance.

I have considered the possibility that these Moroccan teeth represent Jaekelotodus sp which have a nutrient groove and reduced (though doubled) cusplets in the line-drawings in Kent.

What do you think?

----Harry Pristis

Looking at them again, I agree. They don't look like those other Cretodus (arcuatus anyway). They also don't look like any Jaekelotodus teeth I've ever seen either. On top of that, I've never heard of Jaekelotodus teeth from Morocco and I can't find anything to disprove that. It looks as though they both have a nutrient groove and that is what's throwing off all my possibilities. I was looking earlier today for an ID on your teeth and realized I had one of mine wrong. What I had bought as Anomotodon now seems to be a small Striatolamna macrota. I'm running out of ideas for yours Harry, but I am still on the job :D

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Recently Browsing   0 members

    No registered users viewing this page.

×