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Post by Life on Feb 20, 2019 12:58:17 GMT 5
Hey Life, hope you are doing well and Happy New Year to you. can you comment on where you found the pictures of the whale with Megalodon bite marks in the last two pictures below, the one of unknown taxa? Thank you, friend. The images (in question) are taken from the History Channel's Jurassic Fight Club documentary. Also, if I'm remembering correctly, back on the old carnivora many years ago you posted a picture of a relatively large rorqual skull/rostrum on which reseearchers had discovered Megalodon bite marks. Do you still have that pic and if so could you post on this thread? Thanks! The rorqual's skull was disclosed in the National Geography's Prehistoric Predators (Monster Shark) documentary.
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Post by elosha11 on May 19, 2019 2:14:32 GMT 5
Although this is a prehistoric crocodile bite on a fossil whale bone, I thought this should be the place to put. It's very interesting, I've never seen such a fossil. Quite likely scavenging but you never know, given the size of prehistoric crocs. But the fact that they bites marks are on the top and bottom of the centra (which would likely mean it was already separated from other centra) makes it much more likely to be a scavenging type of feeding. Website paleodirect.com/prehistoric-crocodile-bitten-fossil-whale-vertebra-from-lee-creek-phosphate-deposits-wh037/
LARGE PREHISTORIC CROCODILE-BITTEN FOSSIL WHALE VERTEBRA FROM THE FAMOUS LEE CREEK PHOSPHATE DEPOSITS *WH037 1,357.98- AUD SKU:WH037ID:OdontoceteFOUND:Pungo River Formation, Lee Creek - Aurora, North Carolina, U.S.A.AGE:MIOCENE / PLIOCENE: 22 - 4.5 million yearsSIZE:10.75" across x 7" high x 7.25" deepCONDITION:NO REPAIR OR RESTORATION. LAB CLEANED.NOTE:DESPITE OUR PAST HISTORY OF FIELD-COLLECTING IN PHOSPHATE DEPOSITS, THIS IS THE FIRST TIME WE HAVE EVER SEEN SUCH A VERTEBRA WITH OBVIOUS CROCODILE PREDATION BITES.
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Post by elosha11 on May 19, 2019 2:26:15 GMT 5
Another Megalodon (likely) bite mark on a pretty large whale vertebral centra. There's quite a bit of evidence that Megalodon fed on quite large whales, including many large vertebrae and rib bones, caudal bones, flippers, etc shown on this thread. All the more baffling for some recent researchers to presuppose that because they found some bones of smaller prey items, with Meg bites, that Meg must have been primarily a predator of small prey (3-5 meter) whales, pinnipeds, or dolphins. It would be like a researcher a million years from now researching the extinct African lion and concluding because they found some fossil impala bones with lion bite marks, that lions preyed primarily on animals 50 kgs or less. Megalodon and the other large mega-toothed sharks were likely very opportunistic. I think they would readily take prey of any size as long as it wasn't too energetically costly to pursue. And of course, they'd likely scavenge any small, medium, or large carcasses, as that's simply a free meal. Website: paleodirect.com/fossil-sperm-whale-vertebra-with-megalodon-shark-bite-wh035/?setCurrencyId=4RARE GIANT INTACT FOSSIL SPERM WHALE VERTEBRA WITH MEGALODON SHARK BITE FROM THE MIOCENE / PLIOCENE *WH035 1,664.40- AUD SKU:WH035ID:OdontoceteFOUND:St. Mary's River Basin, Georgia, U.S.A.AGE:MIOCENE / PLIOCENE: 22 - 4.5 million yearsSIZE:9" across x 7.5" high x 8.5" deepCONDITION:NO REPAIR OR RESTORATION. LAB CLEANED, SEALED AND STABILIZEDNOTE:SUPER RARE IN THIS SIZE AND PRESERVATION WITH A VISIBLE MEGALODON SHARK BITE!
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Post by theropod on May 20, 2019 2:00:50 GMT 5
elosha11: Does that mean you disagree with the hypothesis that C. megalodon primarily preyed on relatively small prey items? Btw quite funny that the seller’s site claims the megalodon "fed on this vertebra". If that even is a bite mark, it’s heavily remodeled.
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Post by elosha11 on May 23, 2019 9:38:49 GMT 5
elosha11: Does that mean you disagree with the hypothesis that C. megalodon primarily preyed on relatively small prey items? Btw quite funny that the seller’s site claims the megalodon "fed on this vertebra". If that even is a bite mark, it’s heavily remodeled. Yes, that is a funny, and I'm sure unintended, word choice. As if Megalodon intentionally engaged in osteophagy. Do I disagree with that hypothesis? It's really hard to say, and depends on your definition of "relatively small prey." I don't think adult Megalodons regularly sought out relatively small dolphins, pinnipeds, or similar sized whales. Not enough bang for the buck. They'd be relatively hard to catch and not have a very good energy return for a huge predator. That said, there would be times even adults would seek to feed on such animals, and certain evidence (such as Godfrey's fossil centra) suggests subadult Megs may have targeted smaller prey items. STill we have no idea just how often the small prey were targeted by any Megs, adults, or subadults. Now we know during Meg's existence whales were, on the whole, smaller than today's whales. Still, 8-10 meter whales were common and I'm sure frequently preyed upon by Megalodon and other mega-toothed sharks. And we know some other large whales co-existed with Megalodon, such as Livyatan and another rorqual (name escapes me), which was huge, probably not much smaller than a blue whale. Prehistoric sperm whales were also quite large, although not as big as modern ones. We also know that there are Meg bite marks on some quite large centra, ribs, flipper bones etc, which presumably came from a large whale. If I had to guess, I'd think medium-size whales were the most frequent target, whales 8-10 meters. Yet, Meg also sometimes preyed on much smaller items, and likely also at times preyed on much larger whales. For instance, I see little reason why an 18 meter Megalodon wouldn't seek to prey on a 16 meter whale. And perhaps it at times also attacked whales larger than itself, we simply don't know for sure. Where I take issue with the research is to suggest that because a few small prey items from Peru have been found with Meg bites (2-3 instances out of billions of predatory events during Meg's existence), one can leap to the conclusion that these small-size animals were its primary prey source, especially when there's lots of evidence of feeding on much larger animals. It's a conclusion unwarranted by the relatively minuscule fossil record we do possess.
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Post by Grey on Jul 9, 2019 7:59:42 GMT 5
Can someone reminds me how deep are the deepest bite marks produced by megatooth sharks ?
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Post by Life on Jul 9, 2019 14:47:32 GMT 5
elosha11Some images not showing. Can you restore these? Can someone reminds me how deep are the deepest bite marks produced by megatooth sharks ? There are bones with inch+ deep cuts, and there are bones literally sliced in half. Severity of structural damage depend upon numerous factors. The impacted bone was on the receiving end of the main attack or follow-on bites? Which part of the body was struck - covered in thick layers of muscle or blubber? Size of shark involved?
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Post by elosha11 on Jul 10, 2019 1:32:43 GMT 5
elosha11Some images not showing. Can you restore these? Can someone reminds me how deep are the deepest bite marks produced by megatooth sharks ? There are bones with inch+ deep cuts, and there are bones literally sliced in half. Severity of structural damage depend upon numerous factors. The impacted bone was on the receiving end of the main attack or follow-on bites? Which part of the body was struck - covered in thick layers of muscle or blubber? Size of shark involved? Some I might be able to restore, some I can't. I've gone through and reposted some in the past, and I've even downloaded some of the images onto a Word doc, which I've saved at various points on this thread for safekeeping. The problem is that when a website takes off an image, it's gone forever unless I've separately saved it or can find it on a web archive.
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Post by Life on Sept 5, 2019 1:40:10 GMT 5
GreyTake a look at following cases of trophic interactions involving a large Megalodon:- 1. Evidence of Megalodon predation on a dolphin: chesapeakebaymagazine.com/megalodon-bite-marks-found-on-calvert-cliffs-fossil/?ampTL of dolphin = 4m TL of Megalodon = >11m 2. Evidence of Megalodon predation on a pinniped and a dwarf mysticete (separate events): www.sciencedirect.com/science/article/pii/S0031018216305417TL of pinniped = 5m? (probably smaller) TL of Megalodon = >11m TL of dwarf mysticete = 5m TL of Megalodon = >11m Although I strongly disagree with the conclusion drawn in study no. 2. Megalodon would kill and eat anything it could catch. And I really doubt that an adult human would be beneath its notice. I believe that a large Megalodon intimidated/spooked/scared numerous animals away with its mere presence in a particular setting. So why bite marks on the remains of whales are common? Perhaps, large animals such as whales were unable to escape very often? Megalodon had a 'very high calorie intake requirement' during the course of its adulthood, and it was well-equipped for big game hunting on top; connect the dots. Megalodon also attained adulthood at a fast pace. I would not rule out the possibility of 'preservation bias' in fossils as well. It is also possible that numerous examples of trophic interactions involving a Megalodon fell in private hands and/or remain undocumented.
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Post by theropod on Sept 5, 2019 2:22:48 GMT 5
^I highly doubt that pinniped in question was anywhere near 5m. Unless the scale bar is spectacularly off in both figures showing the fossil, that scapula isn’t much longer than 20cm. The owner was likely around 2m rather than 5. Certainly not an elephant-seal sized animal. We also cannot tell how big the shark was from those bite marks with any degree of precision, the only thing that seems clear is that it must have been large (almost any megalodon would potentially qualify here). As Grey correctly points out, we cannot be certain they were even necessarily left by an adult shark. Collareta et al. suggest they likely were , based on the size of the bite marks and the denticulation ("the size and spatial frequency of denticulation of the best-preserved serrated tooth marks observed on the fossil bones here described are much more compatible with large teeth belonging to adult individuals of C. megalodon"--Collareta et al. 2017), but we should not overlook the inherent uncertainty in this (as they basically primarily contrast this with the alternative, less likely hypothesis that they were made by a Cosmopolitodus), or any size estimate based on a mere tooth mark.
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Post by theropod on Sept 5, 2019 3:08:05 GMT 5
Yup, my eyballing-skills are improving, the pinniped is around 2.2 m long snout to tail based on the figured size of the scapula and skeletal of Acrophoca from Berta (2018). Comparing that to megalodon, (the smaller 10m, the larger 17m), I don’t see that as an unrealistic snack for a the 10m meg. The size ratio doesn’t look any higher than that between great white sharks and their preferred prey: media.sciencephoto.com/image/c0428646/800wmwww.apexpredators.com/system/blog_articles/main_images/000/000/326/large/FALSE_BAY.jpg?1499961573i.pinimg.com/originals/9a/21/2a/9a212ae00026fb73e3aad348d0aeed8f.jpgi.redd.it/jxplzz5qq7j21.jpgsecure.i.telegraph.co.uk/multimedia/archive/01890/shark-seal-lure_1890783i.jpgi.dailymail.co.uk/i/pix/2017/11/30/11/46D574D700000578-5132281-image-a-3_1512042691624.jpgBerta, A. 2018. Pinniped Evolution. In: Würsig, B., Thewissen, J.G.M. and Kovacs, K.M. (eds.), Encyclopedia of Marine Mammals (Third Edition), 712–722. Academic Press.Attachments:
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Post by theropod on Sept 5, 2019 3:15:29 GMT 5
Moved this here as our last few posts had little do do with pliosaurs.
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Post by Life on Sept 5, 2019 3:29:04 GMT 5
Moved this here as our last few posts had little do do with pliosaurs. Err, the ongoing discussion wasn't exclusively about Pliosaurs...
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Post by Life on Sept 5, 2019 3:44:57 GMT 5
^I highly doubt that pinniped in question was anywhere near 5m. Unless the scale bar is spectacularly off in both figures showing the fossil, that scapula isn’t much longer than 20cm. The owner was likely around 2m rather than 5. Certainly not an elephant-seal sized animal. We also cannot tell how big the shark was from those bite marks with any degree of precision, the only thing that seems clear is that it must have been large (almost any megalodon would potentially qualify here). As Grey correctly points out, we cannot be certain they were even necessarily left by an adult shark. Collareta et al. suggest they likely were , based on the size of the bite marks and the denticulation ("the size and spatial frequency of denticulation of the best-preserved serrated tooth marks observed on the fossil bones here described are much more compatible with large teeth belonging to adult individuals of C. megalodon"--Collareta et al. 2017), but we should not overlook the inherent uncertainty in this (as they basically primarily contrast this with the alternative, less likely hypothesis that they were made by a Cosmopolitodus), or any size estimate based on a mere tooth mark. Thanks for the pointer. Well, your observation lend further support to my POV. I am not sure about the 'adult' part either but the Megalodon is believed to be very large in the cases of trophic interactions highlighted by me (much larger than even the largest known members of the great white shark and the extinct Isurus Hastalis). Otherwise, authors would have pinpointed that the Megalodon was in the size range of great white sharks so any shark was responsible, I recall a publication in which a juvenile Megalodon is suspected to take its chances with a large rorqual on the basis of dental imprint on one of its rib bones.
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Post by theropod on Sept 5, 2019 14:31:25 GMT 5
Moved this here as our last few posts had little do do with pliosaurs. Err, the ongoing discussion wasn't exclusively about Pliosaurs... But comparing them to other animals, at least.
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