G. Cuvier / Mayumbensis

[Hieronymus]

Hi everybody,

Over here in Europe, atleast in Belgium or the Netherlands, we don't find Galeocerdo cuvier in our miocene/pliocene sediments. The only tigershark we find in these periods is G. aduncus. (although recently some specimens that were found seem to look quite Physogaleus contortus-like).

So, since the internet makes the world so much smaller, I've seen a lot of tigershark teeth from different era's from around the globe. This is also the case with Galeocerdo mayumbensis. Now, my question is the next one: how can you tell the difference between a cuvier and a mayumbensis? Is there a good article about it? Also, please share your thoughts, since it is being found in the USA I would like your (local) views on this topic. I bring this up because there's not a lot of information about this on elasmo.

So in short: what information can you give me about this species(mayumbensis)?

Thank's in advance!

Jeroen

[siteseer]

I have wondered about this species too. To me they look like G. cuvier parasymphyseals with a less-inclined cusp and some enlarged serrations. If teeth of this shape are a separate species, then what do fossil cuvier parasyphyseals look like? I have never seen anyone build an artificial dentition or even a jaw quadrant of mayumbensis.

I'm on the road so I don't have my references or collection to consult but I do have a modern cuvier parasyphyseal and it resembles a mayumbensis though I believe the cusp is somewhat smaller compared to fossil teeth of the same size. It's hard to say. I hope others will chime in on this with evidence more substantial for one side or the other.

[Hieronymus]

I have wondered about this species too. To me they look like G. cuvier parasymphyseals with a less-inclined cusp and some enlarged serrations. If teeth of this shape are a separate species, then what do fossil cuvier parasyphyseals look like? I have never seen anyone build an artificial dentition or even a jaw quadrant of mayumbensis.

I'm on the road so I don't have my references or collection to consult but I do have a modern cuvier parasyphyseal and it resembles a mayumbensis though I believe the cusp is somewhat smaller compared to fossil teeth of the same size. It's hard to say. I hope others will chime in on this with evidence more substantial for one side or the other.

Thank you, that's just the kind of remark I wanted! Pointing out that it' isn't necessarily a new species. Interesting discussion point and like you I hope that others will pick this up and have something more to say about this?

Really, thank you for the reply.

Jeroen

[Hieronymus]

Hmm, so many shark tooth collectors on this forum, more than 70 views and only 1 person is able to give his view on my question. Strange, but thank's anyway siteseer!

[Guest bierk]

Hmm, so many shark tooth collectors on this forum, more than 70 views and only 1 person is able to give his view on my question. Strange, but thank's anyway siteseer!

Well, here's my take on it.

I hunt in Florida and we find a decent number of teeth that would categorized as 'mayumbensis' based on their shape and appearance. I do find a fair number of cuvier teeth as well in my hunting. While I've never compared the 'mayumbensis' teeth I find with a modern jaw of a cuvier to see how they measure up, I must say that a fair number of the 'mayumbensis' do show marked differences from the cuvier teeth I find. I've not seen where some of the mayumbensis styled teeth show any match to cuvier teeth, and I find many that are uniquely different so I don't believe at this time that it is just an uncommon position of a cuvier. I find many different positions of 'mayumbensis' that are far different than the cuvier teeth.

It adds further mystery...

[Hieronymus]

Well, here's my take on it.

I hunt in Florida and we find a decent number of teeth that would categorized as 'mayumbensis' based on their shape and appearance. I do find a fair number of cuvier teeth as well in my hunting. While I've never compared the 'mayumbensis' teeth I find with a modern jaw of a cuvier to see how they measure up, I must say that a fair number of the 'mayumbensis' do show marked differences from the cuvier teeth I find. I've not seen where some of the mayumbensis styled teeth show any match to cuvier teeth, and I find many that are uniquely different so I don't believe at this time that it is just an uncommon position of a cuvier. I find many different positions of 'mayumbensis' that are far different than the cuvier teeth.

It adds further mystery...

Thank you for the reply. I've got an additional question for you. Are your teeth found in-situ? I mean in the fossil layer itself, or ex-situ (sand suppletion, riverfind, beachfind,...). If you find them in-situ: are they found in the same layers, the same formation? Or is mayumbensis found in older formations.

Thank's!

[Guest bierk]

Thank you for the reply. I've got an additional question for you. Are your teeth found in-situ? I mean in the fossil layer itself, or ex-situ (sand suppletion, riverfind, beachfind,...). If you find them in-situ: are they found in the same layers, the same formation? Or is mayumbensis found in older formations.

Thank's!

My mayumbensis are all river and creek finds and hence are mixed in with many other fossils. I believe the mayumbensis I find are out of the Bone Valley Formation, which is known to have cuvier also as I understand it.

I also have some spots that do produce cuvier teeth but not a single mayumbensis tooth at all, and the two sites are both in Florida but approximately 100 miles apart. The site without a single mayumbensis is pliocene but unknown formation name as of yet.

[Hieronymus]

Ok thank's, that's a good argument why they should be distinct species. If mayumbensis would be a tooth position of cuvier, they should also be found in the pliocene sediments.

Any ideas on where to put in in the Galeocerdo lineage? Direct ancestor of cuvier, or a dead end, or...?

[Guest bierk]

Ok thank's, that's a good argument why they should be distinct species. If mayumbensis would be a tooth position of cuvier, they should also be found in the pliocene sediments.

Any ideas on where to put in in the Galeocerdo lineage? Direct ancestor of cuvier, or a dead end, or...?

I do believe mayumbensis is a separate species, and it all boils down to the fact that I don't find just one 'type' of mayumbensis looking tooth. Instead I find a large variety in tooth positions and they are very distinctly different from the cuvier teeth.

I wouldn't know where to put it in the galeocerdo lineage and any attempt by me to do so would be pure speculation so I'm hesitant to say much. But in my mind I somewhat liken it to the shark tooth hill mako situation. While the Isurus planus is found other places besides STH, it does not seem to have a large range despite being apparently a contemporary to the Isurus hastalis in the same deposits. But we do consider them a different species even though they aren't wide-spread. I view the mayumbensis similarly where perhaps it had limited distribution but was indeed a contemporary to other more well known species which include the G. cuvier. But again, I reserve the right to be wrong, as this is just speculation and thinking out loud...

[Hieronymus]

Hi bierk,

thank's again for your explanation, it really helps me to create a vision on this species.

[siteseer]

I do believe mayumbensis is a separate species, and it all boils down to the fact that I don't find just one 'type' of mayumbensis looking tooth. Instead I find a large variety in tooth positions and they are very distinctly different from the cuvier teeth.

I wouldn't know where to put it in the galeocerdo lineage and any attempt by me to do so would be pure speculation so I'm hesitant to say much. But in my mind I somewhat liken it to the shark tooth hill mako situation. While the Isurus planus is found other places besides STH, it does not seem to have a large range despite being apparently a contemporary to the Isurus hastalis in the same deposits. But we do consider them a different species even though they aren't wide-spread. I view the mayumbensis similarly where perhaps it had limited distribution but was indeed a contemporary to other more well known species which include the G. cuvier. But again, I reserve the right to be wrong, as this is just speculation and thinking out loud...

Bierk and Hieronymus,

Yes, Bierk, thanks for your comments. I have seen mayumbensis from the Bone Valley (phosphate mine finds, though not common) but thought that they came out of the Pliocene as well. It may have been restricted to the Late Miocene (or survived elsewhere in the Pliocene) - perhaps the ancestor of cuvier (both being rather large, broad crowned tigers - clearly larger with a broader cusp than the Oligocene-Miocene aduncus). Instead, they may have been close relatives (sister taxa, two species with a common ancestor, mayumbensis being a dead-end). Like cuvier, it appears mayumbensis was a warm-water shark.

Hieronymus, I am also surprised that more collectors have not responded to your question though many may not have enough teeth from which to draw a conclusion. I might have only 2-3 teeth myself but could not resist answering your call.

Yes, Bierk, the planus and hastalis is a similar parallel. It appears that planus may have diverged from hastalis just before "Sharktooth Hill-time" (approx. 15.5 million years ago) but outside the Bakersfield, CA region.

Siteseer

[Hieronymus]

Thank's siteseer for your comment. The picture keeps getting more and more clear, although the real question (ancestor of cuvier or dead end) still remains. Would be interesting if more people would jump on to this discussion and share (even if it's a just a little bit) of their own findings.

Thank's guys!

[makoken]

I do believe mayumbensis is a separate species, and it all boils down to the fact that I don't find just one 'type' of mayumbensis looking tooth. Instead I find a large variety in tooth positions and they are very distinctly different from the cuvier teeth.

I wouldn't know where to put it in the galeocerdo lineage and any attempt by me to do so would be pure speculation so I'm hesitant to say much. But in my mind I somewhat liken it to the shark tooth hill mako situation. While the Isurus planus is found other places besides STH, it does not seem to have a large range despite being apparently a contemporary to the Isurus hastalis in the same deposits. But we do consider them a different species even though they aren't wide-spread. I view the mayumbensis similarly where perhaps it had limited distribution but was indeed a contemporary to other more well known species which include the G. cuvier. But again, I reserve the right to be wrong, as this is just speculation and thinking out loud...

I like that analogy, If you could post a pic. of the two side by side. I would like to see the difference. I hunted the Peace river a couple years ago, and would like to see if there is a Mayumbensis in my finds!!

[Northern Sharks]

All I can add is this, taken from Elasmo.com.

I have teeth of each species, but from different positions, so comparing them doesn't make much sense

The scenario G. latidens -> G. mayumbensis -> G. cuvier works from at least several perspectives.

* First, the time frames are OK: G. latidens (AGASSIZ, 1843) is an Eocene species, G. mayumbensis (DARTEVELLE & CASIER, 1943) is Oligocene - Miocene, and G. cuvier (PERON & LESUEUR, 1822) is Miocene - present.

* Secondly, there is a gradual increase in tooth size, with a typical G. latidens anterior tooth being perhaps 2/3 the size of G. cuvier and G. mayumbensis somewhere between the others.

* Thirdly, there is a gradual change in the inclination of the distal cutting edge of the tooth (see photo). In G. latidens, this is sharply inclined toward the point of the main cusp. In G. mayumbensis it is less inclined and in G. cuvier less yet, in fact, it it now almost horizontal.

* Finally, there seems to be a gradual increase in the complexity of serrations. In G. latidens the serrations are simple, while in G. mayumbensis and cuvier the serrations are complex, with serrations having serrations, but G. mayumbensis seems to have simpler serrations than cuvier.

I don't know where G. aduncas (AGASSIZ, 1843) fits into this. There is a small Eocene tiger shark that has not been classified (possibly G. alabamensis?) that could be a possible precursor for G. aduncas. It has simple serrations while G. aduncas's are complex, and I know of no Oligocene transition species between the two. Possibly G. mayumbensis had two off-spring, G. aduncas and G. cuvier (a "small-toothed" species and a "large-toothed" species).

[Martijn]

Hi Jeroen,

Well I guess I told you my view on the G. mayumbensis ones before.

Here it is again:

Looking at the recent G. cuvier there seems to been quite some 'teeth' differences, ofcoarse within a certain range, when you compare one individual tiger sharkjaw with another tiger sharkjaw.

So yes I think that G. mayumbensis is G. cuvier.

Regards,

Martijn

[Hieronymus]

@ Northern sharks:

Could be possible but I find it hard to believe that aduncas is not in the same line as cuvier for one simple reason: Put an aduncas tooth next to a juvenile tooth from a cuvier and you won't be able to distinguish them, they're completely equal to each other (even in size).

@ Martijn:

Maybe yes, maybe no;-) that's exactly what Im trying to find out now.

It's just the fact that I'm not familiar with mayumbensis-like teeth from the pliocene, or atleast not in the same amount as miocene or oligocene outcrops seem to provide them...

Thank you for thinking with me guys...

[Paleoc]

G. latidens ->G. aduncus ->G. cuvier

G. eaglesomei ->G. mayumbensis ->extinct

I have an acquaintance who deals in modern tiger shark jaws. I have asked him to look for a mayumbensis type tooth in a modern jaw in case it was just a variant of cuvier. He has handled probably thousands of tiger shark jaws and never seen one with mayumbensis type teeth.

Another argument that provides evidence that it is separate species, is that while it is fairly common in Florida, after the Oligocene (where an older version turns up in the Belgrade formation), it doesn't show up in North Carolina or points further north. I have seen and collected thousands of tiger shark teeth (aduncus and cuvier) in the Pungo, Calvert, Choptank and Yorktown formations and have yet to see a mayumbensis tooth, though I have several from Florida from different jaw positions.