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Post by theropod on Feb 22, 2017 18:34:25 GMT 5
What’s weird though is that Collareta et al. actually cite Kallal et al. for an example of bone reactions providing evidence of predation, so that can’t really be it. On the other hand they state that the great white "only attacks cetacean individuals that are considerably smaller than him, and never actively preys upon animals from its own size class" based on the cetacean predation record from Long & Jones 1996 where the biggest prey were 3m beaked whales killed by 5m great whites, so what they seem to be ignoring is Taylor & Mandelman’s 2012 record of attacks on newborn and juvenile right whales.
There’s not much doubt that the bulk of C. megalodon’s prey was made up by the high-energy small cetaceans referred to in the paper. Although I must say there’s not really much new, groundbreaking information in there to support that particular conclusion. Having more material, especially properly documented material, is great, but it doesn’t really add that much to the point in question, after all it’s not that big a sample and it’s not really discernable what’s predation and what’s feeding either.
But both the fossil record and the exact actualistic observations used to suggest that it focused on small prey would also suggest that, just like pretty much every apex predator in earth history, C. megalodon had the ability to occasionally attack prey much larger than what the bulk of its diet consisted of.
I don’t think that’s at odds with the conclusion that the extinction of many small-sized mysticetes negatively impacted megalodon’s ability to sustain itself though. If you take away the preferred, most easily acquired and most abundant prey from giant predators with massive caloric requirements it’s bound to cause some problems for them even if there is other prey around that they have occasionally hunted.
Long, D. J. and Jones, R. E. 1996. White shark predation and scavenging on cetaceans in the eastern North Pacific Ocean. Great white sharks: the biology of Carcharodon carcharias: 293–307.
Taylor, J. K., Mandelman, J. W., McLellan, W. A., Moore, M. J., Skomal, G. B., Rotstein, D. S. and Kraus, S. D. 2013. Shark predation on North Atlantic right whales (Eubalaena glacialis) in the southeastern United States calving ground. Marine Mammal Science 29 (1): 204–212.
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Post by elosha11 on Feb 22, 2017 20:35:26 GMT 5
What’s weird though is that Collareta et al. actually cite Kallal et al. for an example of bone reactions providing evidence of predation, so that can’t really be it. On the other hand they state that the great white "only attacks cetacean individuals that are considerably smaller than him, and never actively preys upon animals from its own size class" based on the cetacean predation record from Long & Jones 1996 where the biggest prey were 3m beaked whales killed by 5m great whites, so what they seem to be ignoring is Taylor & Mandelman’s 2012 record of attacks on newborn and juvenile right whales. There’s not much doubt that the bulk of C. megalodon’s prey was made up by the high-energy small cetaceans referred to in the paper. Although I must say there’s not really much new, groundbreaking information in there to support that particular conclusion. Having more material, especially properly documented material, is great, but it doesn’t really add that much to the point in question, after all it’s not that big a sample and it’s not really discernable what’s predation and what’s feeding either. But both the fossil record and the exact actualistic observations used to suggest that it focused on small prey would also suggest that, just like pretty much every apex predator in earth history, C. megalodon had the ability to occasionally attack prey much larger than what the bulk of its diet consisted of. I don’t think that’s at odds with the conclusion that the extinction of many small-sized mysticetes negatively impacted megalodon’s ability to sustain itself though. If you take away the preferred, most easily acquired and most abundant prey from giant predators with massive caloric requirements it’s bound to cause some problems for them even if there is other prey around that they have occasionally hunted. Long, D. J. and Jones, R. E. 1996. White shark predation and scavenging on cetaceans in the eastern North Pacific Ocean. Great white sharks: the biology of Carcharodon carcharias: 293–307. Taylor, J. K., Mandelman, J. W., McLellan, W. A., Moore, M. J., Skomal, G. B., Rotstein, D. S. and Kraus, S. D. 2013. Shark predation on North Atlantic right whales (Eubalaena glacialis) in the southeastern United States calving ground. Marine Mammal Science 29 (1): 204–212. Of course, we'll never know what exactly happened in the Kallal study of 2010. We know it was likely a mega-toothed shark between 4 to 8 meters. If it was a Megalodon, it was significantly smaller than the cetacean, which the researchers stated would be similar in size to a humpback whale. I'm not sure a flesh grazing would be the only scenario the evidence could suggest. Assuming the whale was not carrying an open would that the shark just bit into (which certainly is a possibility), the shark bite had to pierce around 6 inches of blubber, muscle and leave a serious bite imprint upon the fossil rib. This would suggest an aggressive, hard charging bite, rather than the rather leisurely bites we see from the video of the tiger shark feeding on the sick and/or injured blue whale. Whatever killed the ancient whale, we know it wasn't immediately after this bite, as the whale lived an estimated 2 to 6 weeks after this bite. So we know it wasn't at the point of imminent death when the shark bit it. What I will say is that this is most likely a very serious bite, whatever motivated it and whatever circumstances. If the whale was relatively healthy before the bite, the bite would have done more than just annoy it. It could have removed a section of the whale's flank down to the bone. If this shark were, say 6 meters, this would be a bite radius of two feet or more. This would be a serious wound, even to a large rorqual. It could possibly have died from infection from the wound or such infection could have at least contributed to its death. Theropod, it sounds like you're read the full Collareta paper. It appears that they are not counting great white attacks on newborn/juvenile right whales. I also suspect great whites target and sometimes prey on sizeable young minke whales. Great whites also do occasionally attack and kill (or sometimes fail to kill) large bull elephant seals of similar size to them. In any event, it's hard to know just how much we can analogize great white behavior to Megalodon, but I can't quibble to much about that since we use the great white as a proxy to Megalodon in all kinds of circumstances. I agree that Megalodon focused its efforts usually on the most readily available and easy targets, but I think that includes a quite larger range than the relatively small 5 meter whales and pinnipeds referenced in the article. There's ample evidence of Meg attacking medium size prey such as 20-30 foot cetheroiids, such as the 30 foot whale described in New Scientists "Hell's Teeth," the 9 meter cetotheriid found at Sharktooth Hill that bitten in half in the "Sharkzilla" documentary. There have also been reportedly larger whales with significant Megalodon bite mark damage, (I believe Life has posted a few skeletons and skulls of larger whales with Meg bite damage) but these apparently have not been studied or reported on by the scientific community. |
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Post by theropod on Feb 22, 2017 23:07:20 GMT 5
I didn’t say it was definitely "flesh-grazing" (having expressed that I consider distinguishing it from predation in such cases problematic anyway).
But it is a possible scenario, and a likely one at that. And as I wrote, we cannot look into the mind of a shark to determine whether it intended to kill the whale with its attack, and neither do I think that is important. A shark that size stands no real chance of directly killing a whale that size with a bite to the chest area, so the only point that’s up for debate is whether the shark made a mistake in that regard or whether it attacked deliberately.
Where does the paper reference 5m-figure you cite?
It mentions that the seal was approximately the size of a modern-day steller sea lion and it gives a very approximate size range of 3-4m for the diverse mysticete fauna (which doesn’t have to mean much in regard to the particular specimens in question), but that’s about the most explicit it gets in that regard.
The authors propose that "the target prey of adult individuals of C. megalodon may still have been the highly energetic small- to medium-sized mysticetes (e.g., cetotheriids, typically 2.5 m to 7 m long)". I think the examples you gave of 6-9m cetotheres (is there anywhere with some reliably recorded, detailed information on those specimens including scientific size estimates or are we still relying on TV shows for all our information on those?) fit into that category beautifully.
That’s interesting, do you have data on great white attacks on young minke whales? And what size are we talking about in this case?
I’m aware of great white shark predation on northern elephant seals, but as far as attacks on adult bulls are concerned there seems to be no scientifically documented case that I can find, correct me if I’m wrong. In fact elephant seals are common prey, but the only instances where gender or state of maturity was specified were juveniles (e.g. Klimley et al. 2001).
Klimley, A. P., Le Boeuf, B. J., Cantara, K. M., Richert, J. E., Davis, S. F., Van Sommeran, S. and Kelly, J. T. 2001. The hunting strategy of white sharks (Carcharodon carcharias) near a seal colony. Marine Biology 138 (3): 617–636.
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Post by Grey on Feb 23, 2017 1:49:46 GMT 5
Kallal et al. is a contradiction to the claim that large predatory sharks can't prey on larger preys.
Could a 15-18 m megalodon attack and harm a fin whale-sized prey ? Most likely yes based on Kallal et al., the case of right whales calves attacked by white sharks and the fact that megalodon was pound for pound probably more powerfully armed than any regular white shark, still able to engage sizeable sea elephants. (http://www.sanluisobispo.com/news/local/community/cambrian/article124319429.html)
Would it do it on a regular basis ? No, except for a few exceptions, even powerful predators usually avoid to tackle larger prey items.
Anyway, megalodon was a predator reaching 18 m (and quite possibly more). To my knowledge there are no baleen whales reaching that size recorded from the Miocene or Pliocene. Looking at Lambert 2010 and other more recent papers, there are a few undetermined cetotherid reaching the 10-13 m range, but that's still well below the upper range of adult megalodon size. Coincidentally the only cetacean in the Miocene known to approach this size is the predatory Livyatan.
Although, I'm aware of an apparently gigantic cetotherid from Peru but nothing more precise...
Even in the Pliocene. The large bitten vertebra you linked are impressive elosha but they dont say anything about the size of the whales.
That's the same problem with Purdy 1996, what does he mean by "large balaenopterids" ? Large can mean 10 m as well as 20 m.
Even though it is not yet published but I think the largest most likely case of predation is Alton Dooley cetotherid, reportedly about 10 m long.
Looking at the graphs, I'm currently inclined to follow Pimiento suggestion, really gigantic balaenopterids lineage only evolved after meg was gone.
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Post by spartan on Feb 23, 2017 4:36:45 GMT 5
Couldn't B. sibbaldina be a possible candidate? At least it's from the Zanclean and seems to be gigantic.
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Post by elosha11 on Feb 23, 2017 21:02:12 GMT 5
Couldn't B. sibbaldina be a possible candidate? At least it's from the Zanclean and seems to be gigantic. , thanks for this reference. It does appear that balaenoptera sibbaldina's earliest records are in the Pliocene and that it approached the size range of large blue whales. It arguably has a case for the second largest animal known to exist. See, e.g., greaterancestors.com/balaenoptera-sibbaldina/Theropod, in addition to the article Grey provided of a great white attack on a large (but still not fully grown) elephant seal, here's other examples of great white attacks on bulls. I can't tell for sure if they are full grown in the first two pics, but they do appear quite sizeable. [Note: I found a fourth picture of an attacked bull, but lost the link before I could post]     As to the above pic, this is the description from www.pelagic.org/montereybay/pelagic/greatwhiteshark.html"In the foreground a sub adult bull carries the scars of an encounter with T-Rex. While bull elephant seals are extremely tough and do not go quietly when attacked, even alpha bulls are a potential target for the worlds largest known predatory shark, the white shark, C. carcharias." B ull elephant seal killed by great white Also see copyrighted image at frankbalthis.photoshelter.com/image/I0000MD1DgRUkKjs "Shark wound near tail of bull elephant seal at Ano Nuevo SR"As to potential great white attacks on juvenile minke whales, see below youtube video which I posted before on WoA. The shark is sizeable, estimated at 18 feet and the juvenile minke whale is around 12-14 feet. I think this is likely a predation based on several facts. First, the carcass appears to be very fresh, and most importantly, it carries a deep bite in near the tail, which appears to have broken the vertebrae and almost cut the tail in half. That is a tell-tale sign of a great white shark bite on a large and fast prey item such as this.  www.witn.com/home/headlines/Coast-Guard-spots-great-white-shark-eating-off-Beaufort-Inlet-373255521.htmlI think large great sharks opportunistically attack prey items approaching their own size on occasion. I wouldn't call it frequent, but it's not rare either. That may, or may not, have any impact on what size prey a Megalodon may have targeted. As for the size of the seal and whale referenced in Collareta study, you have obviously read the paper. The public new articles on the paper that I read stated that fossils suggested animals of around 5 meters. If they were estimated as smaller than that in the actual paper, than the researcher's estimates obviously must be credited over the news articles. I think 2.5 to 7 meters is quite a bit different than the 6-9 meter samples I proposed. In addition, there was the recent skull of a cetacean in Virginia bearing Megalodon teeth marks was estimated at around 25 feet. (posted in Shark bitten whale bones thread) I don't think there should be any doubt that Megalodon could and likely did kill prey items in the 7-10 meter range on a regular basis. The real question is whether there were larger whales around during Megalodon's existence, and if so, whether Megalodon actively targeted them for predation. Also, I don't think merely because such examples were seen on tv should discredit them. For instance, Dr. Chuck Ciampaglio, a well known and respected authority, personally examined the whale remains in Shark Tooth Hill and believes the whale was at least 25 feet long and appeared to be bitten in half by a Megalodon. Grey, as mentioned I believe Life has posted both here and on Carnivora evidence of Megalodon bite marks on some other sizeable ceteacean skeletons and also I believe he cited an example of a fairly large rorqual skull with a Meg tooth fragment found embedded in it. But he would need to clarify where he posted that and the extent of the information known. Good points as to the vertebraes I posted. We can't know exactly which whales species they are, or how large they were. Nor can we know where these fossil vertebraes were positioned in the whale's skeleton; they could be cervical, thoracic, lumbar, or even caudal. So we cannot be sure we have the largest ones. However, I do note for the huge brown vertebrae I posted, the seller of the fossil stated it was found among associated sperm whale teeth and Megalodon teeth, which is why they believed it to be a sperm whale. This is a very rough estimate, but the size of that vertebrae seems to correspond to the sizes of the vertebrae in the sperm whale below, which was 41 feet long.  www.theboneman.com/spermwhaleskeletons.htmlI will also note that some of the other fossil vertebrae I posted compare favorably to the size of adult grey whale vertebrae such as this one.  EDIT: 4/14/17 - I found the other picture of a male elephant seal attacked by a great white shark that I mentioned before. It's now the fourth picture.Edit 1/24/18 - Added fifth and sixth pictures of elephant seals. |
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Post by spartan on Feb 23, 2017 21:50:50 GMT 5
Poster Session IV ( Saturday, November 8, 2014, 4:15 - 6:15 PM) A LARGE BALAENOPTERI D SKELETON FROM THE EARLY PLIOCENE OF THE NORTH SEA SHEDS LIGHT ON THE AFFINIT IES OF 'BALAENOPTERA' SIBBALDINA (MAMMALIA, CETACEA, MYSTICETI) BISCONTI, Michelangelo, San Diego Natural History Museum, San Diego, CA, United States of America, 92101; BOSSELAERS, Mark, Royal Belgian Institute of Natural Sciences, Brussels, Belgium A large balaenopterid skeleton was found in the early Pliocene Kattendijk Sands Formation at Kallo, a few kilometers fr om Antwerp (Belgium). The skeleton includes most of the skull, earbones, the dentary, some vertebrae, hyoid, some carpals, scapula, humerus, radius, ulna, some chevrons, and a number of ribs. The supraoccipital is around 570 mm in length and 1070 mm in wid th (at the level of the posterior end of the lambdoid crest). The transverse diameter across the occipital condyles and the foramen magnum is 240 mm. The specimen is gigantic in size. The rostrum shows long ascending processes of the maxillae with have bal aenopterid - like shapes. The periotic has balaenopterid - like characters in the shape of the anterior process and of the pars cochlearis. However, differing from Balaenopteridae, the supraorbital processes of the frontal are narrow. Compared to other balaeno pterids, this specimen shows clear affinities with 'Balaenoptera' borealina , a taxon based on fragmentary materials. This specimen adds new morphological information to the study of balaenopterid systematics and phylogeny. A phylogenetic analysis revealed that it was close to 'Balaenoptera' siberi and that both were well nested within Balaenopteridae. www.researchgate.net/profile/Ferhat_Kaya/publication/269694925_Diachronous_Evolution_of_Molar_Crown_Height_in_Old_World_Hipparion_Lineages_Under_Climate_Change/links/54928d280cf2991ff5561621.pdf?origin=publication_listDoes anyone know how these measurements compare to those of other baleen whales? |
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Post by Life on Jun 7, 2017 0:45:09 GMT 5
What about Eltanin impact?
A large comet slammed into Pacific ocean about 2.5 million years ago. It might have destroyed a large number of coastal habitats around the Pacific in a short span and may have instigated a chain of events with far-reaching consequences in the long-term.
Surprisingly, research on this subject is scarce.
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Post by Infinity Blade on Jun 7, 2017 1:49:45 GMT 5
Wow, I didn't know there was an extraterrestrial impact that long ago. Scientific elucidations on how that affected Otodus megalodon would be interesting.
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Post by Life on Jun 7, 2017 18:09:03 GMT 5
Wow, I didn't know there was an extraterrestrial impact that long ago. Scientific elucidations on how that affected Otodus megalodon would be interesting. Indeed. My reaction was similar when I learned about this event. A species as powerful and versatile as Megalodon won't phase out easily. I suspect a complex sequence of events over the course of time. It did not cross my mind even once that there might be an extraterrestrial dimension to this. As we delve deeper into the Pliocene epoch, more surprises lay in store for us. |
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Post by neogeneseamonster on Jun 7, 2017 19:41:37 GMT 5
The Eltanin impact is quite an interesting candidate for sure. But are there any other major species that went extinct around 2.5 mya?
It is hard to think that only a few number of apex predators were affected by such global impact.
However, I do think the event might have severely destroyed shallow nursery area (which is more vulnerable to natural disasters like mega-tsunami induced by the meteorite impact).
BTW, are there any published data about sirenian diversity around this period? The fate of this group might influence the ecology of C. megalodon (especially the juveniles).
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Post by spartan on Jun 27, 2017 1:33:27 GMT 5
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Post by theropod on Oct 16, 2017 1:54:34 GMT 5
Has this been posted yet?
From this year’s SVPCA (https://svpca2017.com/abstracts/)
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Post by Infinity Blade on Oct 17, 2017 4:17:39 GMT 5
Hmm, so it definitely doesn't seem to have been a Megalodon only thing. Not sure if that was actually how scientists thought of it before, but it was how I thought of it.
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