Extinct Mako Teeth, which is correct?

[lesofprimus]

I have 2 fossil Mako teeth labeled as Carcharodon hastalis in my collection, and I'm now questioning the correct designation for them.

 

The other two classifications I am referring to are:

Cosmopolitodus hastalis

Isurus hastalis

 

How should I label them correctly?

[Ludwigia]

I think that Cosmopolotidus is the currently recognized name. The others are socalled synonyms.

[Kikokuryu]

6 minutes ago, Ludwigia said:

I think that Cosmopolotidus is the currently recognized name. The others are socalled synonyms.

Was it? I thought Carcharodon hastalis is the current favorite, at least, last I recall.

 

In regards to calling it a mako, the "giant mako" or "extinct mako" is not a true mako as it is more closely related to white sharks than to makos, but common names are arbitrary anyway like how Paleocarcharodon is often called a pygmy great white despite it being an Otodontidae.

Edited October 27, 2021 by Kikokuryu

[Thomas.Dodson]

20 minutes ago, Kikokuryu said:

Was it? I thought Carcharodon hastalis is the current favorite, at least, last I recall.

 

In regards to calling it a mako, the "giant mako" or "extinct mako" is not a true mako as it is more closely related to white sharks than to makos, but common names are arbitrary anyway like how Paleocarcharodon is often called a pygmy great white despite it being an Otodontidae.

I was under the impression that Cosmopolitodus was the currently recognized name although I can't recall any papers/opinions for this off the top of my head.

[lesofprimus]

Thanks for the replies guys...

[sixgill pete]

The current thinking as I understand it is that this "mako" is the predecessor to the great white. If that is correct then Carcharodon hastalis would be correct. However, this all depends on who you talk to. I have some of mine currently labeled as Carcharodon and some Cosmopolitodus. As @Thomas.Dodson stated, this shark was not a mako. So Isurus is not correct.

 

I guess if you labeled them C. hastalis you would be correct no matter what.

[IsaacTheFossilMan]

Some species under Carcharodon can be put under Cosmopolitodus, Isurus or even Macrorhizodus.

 

hastalis I have never seen put under Isurus nor Macrorhizodus, so it is usually just called C. hastalis for simplicity.

If you want more detail, here is my understanding of the whole situation:

 

hastalis was first officially described in 1843 by Louis Agassiz. ^{(L. Agassiz, 1843: Recherches sur les poissons fossiles)}

However, when also described, he put it in the genus Oxyrhina. Two different morphological traits were described, a narrow form, and a broad form. Agassiz put these under two different species, "O. hastalis" for the narrow, and "O. xiphodon" for the broad form

 

Once Oxyrhina became a dustbin-taxon in the 20th Century, it was discarded. Holec et al. (1995) reviewed these teeth and put them under Isurus. 

A widely accepted (though not entirely due to a study by Whitenack and Gottfried in 2010) event happened in 2001, when Ward & Bonavi decided that they are in fact the same species, and discarded I. xiphodon. Byebye!

 

Either in the same study by Ward & Bonavi, or a later one in the same year, they re-examined this species, and determined that it was more related to the great-white, not a mako, and put it under Cosmopolitodus. (fun fact: poor Glikman suggested this in 1964, but it was regected. Oh how we learn! )

 

Ehret et al. then, in 2012, studied it further, cementing the theory that it was an ancestor to the great-white, and also proposing it to be moved into Carcharodon, stating that one of two differences was a lack of serrations in hastalis. They went on to show examples of late-Miocene hastalis specimens showing some serrations.

They also proposed the possibility of Carcharadon absorbing all of the species in Cosmopolitodus. This hasn't been generally accepted yet, and is under debate. 

 

This is the current consensus:

Cosmopolitodus hastalis is believed to be the ancestor of two lineages - Carcharodon from the broad-form, and from the narrow-form, two extinct sharks.

 

Have a nice family tree I typed out showing the relation between hastalis and its close relatives.

   ┏━ Isurus schoutedeni
━━━┫
   ┃  ┏━ Isurus praecursor
   ┗━━┫                                      ┏━ Cosmopolitodus planus
      ┃  ┏━ Isurus desori           narrow ━━┫
      ┗━━┫                            ┃      ┗━ Carcharomodus escheri
         ┗━━ COSMOPOLITODUS HASTALIS ━┫
				      ┃     ┏━ Carcharodon hubbelli
                                    broad ━━┫
					    ┗━ Carcharodon carcharias

 

Here is a broad-form tooth: https://en.wikipedia.org/wiki/File:Isurus_hastalis_labiale_cm.JPG

 

And here is a narrow-form: https://en.wikipedia.org/wiki/File:Lamnidae_-_Cosmopolitodus_hastalis.JPG

 

 

Yours appear to be both broad-form. You have the teeth of a direct ancestor to our great white!

 

[IsaacTheFossilMan]

Things aren't all bad for Leonid Glikman, though - he had the genus Glikmanius named after him. I think that's a pretty badass name for a shark, too! "Glikmanius" sounds pretty neat...

 

To cap things off, yours are Cosmopolitodus hastalis, the broad-form variety. In the future, this could be Carcharodon, but I think that it's settled down for now.

[IsaacTheFossilMan]

20 hours ago, Ludwigia said:

I think that Cosmopolotidus is the currently recognized name. The others are socalled synonyms.

 

Synonyms, not quite. Isurus is no longer accepted (yay synonyms!), and Carcharadon is in debate.

[IsaacTheFossilMan]

20 hours ago, Kikokuryu said:

Was it? I thought Carcharodon hastalis is the current favorite, at least, last I recall.

 

In regards to calling it a mako, the "giant mako" or "extinct mako" is not a true mako as it is more closely related to white sharks than to makos, but common names are arbitrary anyway like how Paleocarcharodon is often called a pygmy great white despite it being an Otodontidae.

 

Cosmopolotidus is the current, however you are right about the mako comments

Edited October 28, 2021 by IsaacTheFossilMan

[siteseer]

18 hours ago, sixgill pete said:

The current thinking as I understand it is that this "mako" is the predecessor to the great white. If that is correct then Carcharodon hastalis would be correct. However, this all depends on who you talk to. I have some of mine currently labeled as Carcharodon and some Cosmopolitodus. As @Thomas.Dodson stated, this shark was not a mako. So Isurus is not correct.

 

I guess if you labeled them C. hastalis you would be correct no matter what.

 

Hi Don,

 

As i understand it, all teeth that would be referred to Cosmopolitodus could also be referred to Carcharodon.  If that's the case, Carcharodon has priority over Cosmopolitodus and would be the valid genus.  Cosmopolitodus became the hip name to use for a while but there was always the nagging realization that if hastalis could not be assigned to Isurus and was the direct ancestor to Carcharodon carcharias, why was Cosmopolitodus being re-erected instead of just going to Carcharodon?  The only difference between hastalis and carcharias is the presence of serrations.  Why would they belong to separate genera? 

 

Many ideas in science become accepted only over years.  In the case of Isurus hastalis, it took a while for most people to accept that it was the ancestor of the great white even though many were getting on board back in the 80's.  There was a time earlier in the century when the species was assigned to Oxyrhina.  The trend is increasing acceptance of Carcharodon.

 

The thing to remember with all the names in biology is that each described taxon is an official proposal based on what is known at the time.  It's not a birth certificate (and even a name on that might be changed later).  An author is proposing a name.  It will be shown to be well-supported or not under the scrutiny of researchers of the time and in the future as more specimens of it and its relatives are found and as ways to examine them are devised and developed. 

 

Jess

[R0b]

On 10/28/2021 at 8:42 PM, siteseer said:

Why would they belong to separate genera?

Lumpers vs Splitters

[FB003]

On 10/27/2021 at 5:12 PM, Kikokuryu said:

Was it? I thought Carcharodon hastalis is the current favorite, at least, last I recall.

 

In regards to calling it a mako, the "giant mako" or "extinct mako" is not a true mako as it is more closely related to white sharks than to makos, but common names are arbitrary anyway like how Paleocarcharodon is often called a pygmy great white despite it being an Otodontidae.

This is what I read as well.