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Boesse

Re-dating the extinction of Otodus/Carcharocles megalodon

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ynot

Nice job and a big help with dating megs.

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rebu

What an amazing work. I am sure it wasn't easy to do all the research and must have been frustrating at times. Thanks to persistence and knowledge of people like you we will eventually get to find out the true story about our past. 

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Tidgy's Dad

Excellent work. 

Several forum members have already excitedly posted about this, it's glad to hear it from the horse's mouth, so to speak.:)

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FossilsAnonymous

Amazing work!

 

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DPS Ammonite

Thanks Robert. We were waiting for you to announce your own paper. 

 

You are doing what others have done to figure out what happened during extinction events such as the Late Cretaceous event: reducing the range of errors of dates to figure out the sequence of events.

 

Maybe Megalodon which has been around for about 19 million years was replaced by new and improved models such as the Great White Shark that you mentioned. @Boesse Did Megalodon last longer than the average shark species? Somewhere I read that the average species (which species?) last about 3 million years. I suspect without good proof that sharks might last longer since their basic body plan has been around for a long time.

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WhodamanHD
1 hour ago, DPS Ammonite said:

Somewhere I read that the average species (which species?) last about 3 million years.

Methinks any attempt to quantify the time an average species lived for would be futile. The variables are so numerous, complex, and sometimes random that I don’t think there would be any meaningful pattern. We struggle to define where one species ends and another begins, which makes it hard to come up with a solid duration for even one.  Additionally, such variance exists for duration that even if one managed an average it would likely be useless, pushed and pulled by various outliers. 

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UtahFossilHunter

Wow, nice job! Thanks for sharing it with us. :dinothumb:

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verydeadthings

Congrats on the paper! I love to see the scientific community interact with non-professionals (who in many cases are experts in the field, regardless of affiliation). So does this rule out the extinction being related to the closing of the isthmus of panama? Could the extinction be related to changes in ocean circulation which reduced the availability of large prey?

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Boesse

@verydeadthings In my opinion - and what we wrote in the paper - the isthmus of Panama closure was likely too localized, though that temporally does make some sense. I'm not convinced oceanographic changes from that closure would have affected C/O megalodon in places like the Indian Ocean and the Mediterranean.

 

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sharkdoctor

great paper and interesting approach!

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UtahFossilHunter

Saw this report on Scishow on Youtube

 

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Ludwigia

What an enormous project! Can you estimate how many man-hours you guys put into it?

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The Amateur Paleontologist

Good job! That's quite incredible :D

-Christian

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Monica

I brought in a megalodon tooth to school yesterday to show my students (I bring a different fossil every Friday - we call it "Fossil Friday" and I'm pretty sure it's their favourite day of the week :)), and I was able to give them this new information regarding the extinction date of the beast.  They were very impressed with both the tooth and the information given, so thanks for the science lesson! :dinothumb::meg:

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siteseer

Bobby,

 

I just read the paper.  As noted above, it was very thorough.  You and your colleagues addressed every question I had.  In fact I took out a piece of note paper to list my comments but I didn't end up writing much.  You took away all my "yeah, but..." responses.  For example, I always understood that the San Diego Formation was wholly late Pliocene in age so it seemed a megalodon tooth from it was all the evidence needed to establish a late Pliocene occurrence.  You addressed the occurrence listed by Kemp (1991).  I guess I never looked close enough at the specimen he noted.

 

You just touched on Parotodus benedeni though it's the same story.  It co-existed with megalodon (though followed a more pelagic and perhaps more specialist lifestyle) across the Miocene and also appears to have died out sometime in the Pliocene.  Parotodus is always rare to extremely rare except perhaps from the Tirabuzon Formation, but even in that, you couldn't call it common.  I think that's important - two large marine predators who happened to be closely-related dying out in about the same geologic instant.  And yes, it seems significant that the great white shark survived past whatever killed them off and even prospered.  The new model might have been somehow more energy-efficient than the old ones. 

 

The appearance of the killer whale might have had more significance.  The rare occurrences you noted (Japan, Italy) also indicate a distribution not reflected in the fossil record so far.  However, I do understand that a killer whale of the Pliocene might not have yet been the efficient pack predator it often is today.

 

It was also interesting to read about the current status of the Fernando Formation.  I started collecting fossils in the late 80's and it seemed a number of southern California collectors had shells and shark teeth from it (sites now gone due to land development).  I gathered from them that the Fernando was a name still used but it was from a previous generation of geologists none of whom formally defined it - something ripe for reinterpretation.  It was just understood.  It appears at least some of the old finds are now said to be from the Repetto.

 

Great paper.

 

Jess

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ashcraft

Isn't it just as likely that great whites/orcas became more common because of the dwindling number of megs allowed a foothold into the niche, rather then causing the extinction?

 

Brent Ashcraft

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Scylla

Thanks for the explanation and the paper. :notworthy:

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