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Post by Life on Oct 24, 2019 19:36:30 GMT 5
1 You're asking me why a species will have trouble evolving next to a supposedly supreme and dominant species that already occupies the same place in the ecosystem? What happened to the enormous pressure it has to face to evolve as such in the first place? 2) I addressed that in the above post. there's NO WAY a relatively blunt tooth will leave a clearly identifiable trace on a tooth several times smaller than it. 3) I really have doubts that a giant hypercanivorous whale can evolve locally. Especially if it was a social creature(which was likely imo). The large prey demands would be unparalleled. Also, teeth found in Australia are almost certainly of the livyatan type, is that cosmopolitan enough for you? 4) erm... Here's a story..stem physeteroids actually SURVIVED. Unlike megalodon. They adapted. They are still thriving, in their modern form! Time to address your queries and misconceptions. Massive radiation of baleen whales in Miocene due to environmental factors (20 - 5 Ma range):  [1]- is believed to have facilitated emergence of Livyatan-types in Miocene (13.8 - 11.6 Ma range):  [2]NOTE: Gigantic Livyatan-types (e.g. Livyatan melvillei) seem to replace Orca-types (e.g. Brygmophyseter shigensis) in the Southern hemisphere around 13.8 Ma mark. However, baleen whales were becoming larger over time:  [3]Bigger Baleen whales were harder to kill accordingly?ORCompetitive pressures from 'gigantic sharks' proved too much eventually.OR BOTH--- TAKE YOUR PICK --- To give you additional perspective, take a look at lifespans of stem physeteriods in the Northern hemisphere (Lee Creek sector):  [2]"Life history can provide substantial insight into the ecology of a taxon. Given that all that remains of physeteroids from Lee Creek Mine is largely teeth, any information to be gleaned from teeth about their place in the mid-Atlantic Pliocene ecosystem will be valuable. The similarity of life history inferred for our extinct physeteroid to that of D. leucas, the beluga whale, discussed above might prove helpful in this regard. The rapid growth, early maturation, and relatively short life span of both taxa could arise from a similar selective pressure. Although fairly large animals themselves, belugas are ecologically quite distinct from other large odontocetes in that they experience significant predation from polar bears and more commonly killer whales (Brodie, 1971; Shelden et al., 2003). Roff (2002) and Brown and Sibly (2006) recognize extrinsic mortality as a key influence on life history strategy. When resources are not limiting but extrinsic mortality is high, a fast life history strategy offers a distinct advantage—individuals genetically predisposed to growing fast and reproducing early have a higher fitness than others, and the population shifts over time toward individuals with those traits (Stearns, 1992). High predation pressure driving fast growth and early maturation is linked to shorter life spans (Huang et al., 2008), because senescence begins after the initiation of reproduction. Early maturation has been linked to high extrinsic mortality in a number of taxa (e.g., Charnov, 1990; Stearns, 1992; Migliano et al., 2007; de Magalhaes and Costa, 2009; Ricklefs, 2010). Phocoenids such as the harbor porpoise, for example, include some of the fastest-maturing and shortest-lived odontocetes (Van Utrecht, 1978), and they experience high extrinsic mortality attributed to predation by sharks and killer whales (Jefferson et al., 1991; Long and Jones, 1996) and to direct competition from delphinids (Ross and Wilson, 1996). Interestingly, extant kogiids, although much smaller than these Pliocene relatives, also exhibit unusually early maturation and short life spans for their size. Like the phocoenids, these traits are attributed to high predation pressure (Plon, 2004), suggesting an ecological if not an evolutionary link with the Lee Creek physeteroids." [2]---Your argument about Livyatan melvillei being the ULTIMATE PREDATOR of Neogene is contingent upon "colorful assumptions in large part." Heck, I provided fossil evidence of a Megalodon taking good care of a Livyatan-type cetacean in the Northern hemisphere: theworldofanimals.proboards.com/post/47824Something to consider. REFERENCES[1] Marx, F. G., & Fordyce, R. E. (2015). Baleen boom and bust: a synthesis of mysticete phylogeny, diversity and disparity. Royal Society Open Science, 2(4), 140434. [2] Gilbert, K. N., Ivany, L. C., & Uhen, M. D. (2018). Living fast and dying young: life history and ecology of a Neogene sperm whale. Journal of Vertebrate Paleontology, 38(2), e1439038. [3] Pyenson, N. D. (2017). The ecological rise of whales chronicled by the fossil record. Current Biology, 27(11), R558-R564. Grey elosha11 theropod Livyatan holotype died young? See above. Probably a Megalodon was responsible. |
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Post by dinosauria101 on Oct 24, 2019 19:40:30 GMT 5
LifeI think you made a good point on the last page. Megalodon seems like the MUCH better macropredator of the 2 animals
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Post by prehistorican on Oct 24, 2019 19:44:47 GMT 5
I have seen some people claim 24m, 130 tonnes Livyatans scaling up from theropod1’s Livyatan estimates to the McLain size estimation of a sperm whale (24m) and claiming it was a giant orca essentially, with abilities of tool use due to its large brain (lol).
Essentially what Grey was saying I definitely see more awesomebro minsinformed calculations of Livyatan in the future, I wouldn’t be surprised if they scales it to 30m claiming it was “how big sperm whales in the past used to be” (referring to dubious whaling records). Then I also notice them “””mistaking”” 10m as a hard maximum for the shark.
Livyatan is overhyped in order to make it more “awesome” than the shark such as what happened with JP3 Spinosaurus killing the T Rex to show how powerful it was. Unfortunately a very large amount of people thinking a Megalodon vs Livyatan is the same as a Great White vs Orca. Yes there are definitely Megalodon fanboys citing the 20m 103 tonnes size figure, but in general the public and online Livyatan definitely is more overhyped.
I’m not a hundred percent sure about real paleontologists thoughts on this...
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Post by Life on Oct 24, 2019 19:48:31 GMT 5
Life : Yes, but it seems you ignored my point. In fact I tend to think, based on available evidence (Govender et al. 2019, Piazza et al. 2019, Loch et al. SVP 2019), that Livyatan was most likely restricted to the southern hemisphere, although it is too early and we have too few fossils to say anything conclusive yet. Fossil record of ancient sperm whales = very rich Fossil record of ancient sharks = very rich The fact that Livyatan-types do not appear to be widespread (limited to Southern hemisphere) even in the Miocene (a relatively stable epoch), does not bode well for 'assumptions' in this thread that these cetaceans were peers of Megalodon in big-game hunting and/or otherwise. The reason for this likely has nothing to do with megalodon at all. Again, how do you know? This is exceedingly bold statement. Competitive pressures wasn't an issue for Megalodon [only] (like some authors seem to suggest), this was an issue for all macropredators of the time. In fact, Megalodon had necessary adaptations to not only cope with these pressures but to anchor itself to the top of the food chain(s) in any environment it inhabited (gigantism; regional endothermy; superb killing apparatus; robust physiology - you name it). Continue to read below. Megalodon existed in the southern hemisphere as well, alongside Livyatan, seemingly for several millions of years. In fact Livyatan (and raptorial physeteroids in general) seem to have evolved to fill their niches despite the presence of large members of the Carcharocles lineage since the late Oligocene. With the recent suggestion (SVP 2019) that Livyatan may have foraged at high latitudes, and previous suggestions that megalodon may not have been suitable for these habitats, it seems increasingly likely that Livyatan was adapted to colder climates, and that the tropical circle might simply have acted as a dispersal barrier due to that. Yes, Megalodon had a cosmopolitan distribution throughout the course of its existence, and fossil records and/or biomechanical considerations suggest Megalodon being at top of the food chain throughout as well. As for co-existence of Livyatan melvillei and Megalodon lasting several millions of years: [1]- Unsubstantiated from fossil records, or a belief grounded in the presence of other stem physeteriods which relatively lasted much longer. With the recent suggestion (SVP 2019) that Livyatan may have foraged at high latitudes, and previous suggestions that megalodon may not have been suitable for these habitats, it seems increasingly likely that Livyatan was adapted to colder climates, and that the tropical circle might simply have acted as a dispersal barrier due to that. being restricted to colder climatic conditions? Give me a break. Fossilized remains of this species have been found in locations such as Peru, Chile and Argentina, and none of these regions were POLAR and/or really cold during the course of Miocene. Marine mammals are warm-blooded (endothermic homeotherms), and therefore, in a decent position to cope with shifts in water temperatures. Gigantism is actually an advantage in this respect. WH023 suggest that Livyatan-types 'attempted' to have a presence in the Northern hemisphere, but did not succeed? But your suggestion that that tooth, which was from the US, belonged to Livyatan (speculation, of course). Do you think it was restricted to the southern hemisphere, or not? I use the term ' Livyatan-types' for a reason. WH023 have a pronounced crown with wear-and-tear from macrophagous biting. This tooth perfectly resemble a tooth-type in Livyatan holotype as well. I have provided sufficient evidence in my previous posts. So why is this even an argument now? I certainly agree with some material on this thread giving a "deeply unrealistic projection" of Livyatan’s capabilities or "strength"? For example, comparison of large restored megalodon jaws to the holotype of Livyatan, with major amounts of forced perspective in them. Hmm. This might disappoint you but ancient stem physeteriods fall into the TL range of (9 - 10 m) on average - assuming largest known individuals.  [1]Livyatan holotype is an outlier in size for stem physeteriods. Or statements like this, which implies evidence that megalodon preyed on Livyatan, when such evidence does not exist. Excuse me? It is utterly unusual to see a tooth of a massive stem physeteriod bearing imprints of Megalodon's teeth (WH023) - one cut is deep and the remainder look like follow-on(s). Deep cut indicate a 'disabling bite' which most likely led to dislodging of WH023 from the jaw structure of its owner. Here is my explanation: theworldofanimals.proboards.com/post/47824WE aren't looking at a mere scavenging mark from a small shark in this case. People have found remains of cetaceans literally cut in half (upperhalf and/or lowerhalf sections entirely missing), and they rightfully suspect involvement of Megalodon in these cases. Case study # 1: www.businessinsider.in/How-The-60-Foot-Long-Ancient-Shark-Megalodon-Ripped-Apart-Giant-Whales/It-would-make-sense-if-it-could-eat-large-prey-since-its-sheer-size-would-have-required-lots-of-calories-just-to-keep-moving-/slideshow/25699747.cmsCase study # 2: www.besttravelwriting.com/btw-blog/great-stories/adventure%e2%80%94bronze-category-winnerjurassic-shark/Megalodon tearing through the jaw structure of a stem physeteriod, is possible in view of its sheer size and/or biomechanical considerations. Please refer back to my explanations on bite marks from before. Bite marks that are not healed are not unambiguous evidence for an attack on a living animal like you seem to imply. At best, a large number of such bite marks, or placement particularly indicative of an attack, might provide a decent indication in that direction. A single unhealed bite mark can just as easily be scavenging as it can be predation. Extant sharks scavenge too, so it is not a big stretch to expect that a megalodon that found a Livyatan carcass (if that really is a Livyatan tooth, as you claim, and if that thing even really is a bite mark) would have fed on it. Your skepticism is duly noted. WE do not understand modern sharks properly, let alone extinct sharks. Megalodon gives the impression of being a very aggressive shark, particularly in view of a trophic interaction involving a juvenile Megalodon which attacked a large whale and breached its chest cavity in the process. Modern era sharks are clearly lacking in this capacity and do not exhibit this kind of behavior. You will probably have us all believe that Megalodon was a helpless pampered bunny and/or too scared to take its chances with other macropredators.  Also, as sam1 correctly points out, the comparison is very lop-sided as it is. For all we know, even if Livyatan had fed or preyed on megalodon regularly, we would have slim chances of ever finding fossil evidence of this. Moreover, Livyatan bite marks would probably be a lot more difficult to identify as such than megalodon bite marks, since crushing and blunt fracturing are easily mistaken for preservational artifacts rather than biological traces. Paleontologists have uncovered concrete evidence of trophic interactions involving Mosasaurs, Pliosaurs and even ancient cetaceans including Basilosaurus isis [2]. So many fossilized bones of ancient whales have been found by now but where is the evidence of imprints of Livyatan-types in them besides mere assumptions? What can you show me in this regard? Cuts not so much, though I do have to say that that supposed "bite mark" on the "Livyatan" tooth from Georgia could just as easily be from a pickaxe. Salute to your 'colorful' thinking, my friend (a REWARD might be appropriate?). The wielder was a master of 'pickaxe crafting'... Oh wait. A blow from a pickaxe would literally destroy a fossilized tooth. As for abundance of Livyatan fossils, this is again not indicative of anything relating to dominance or ecological success, as you seem to be implying. Shark teeth are simply astronomically more common as fossils because due to their tooth replacement, while a Livyatan can only lose its teeth/die once. Members here are going as far as to claim that Livyatan melvillei could dominate an adult Megalodon in a one-on-one encounter, and being a peer of Megalodon in big-game hunting. Isn't this overreaching? Where is the evidence? This is why I turned to fossil records for potential answers. The impression WE have from fossil records is that Livyatan-types are visible in the Southern hemisphere but not successful in the Northern hemisphere (competitive pressures?). And Livyatan melvillei, in particular, wasn't a long-lasting species. See my response to member sam1 above! Very telling. REFERENCES[1] Gilbert, K. N., Ivany, L. C., & Uhen, M. D. (2018). Living fast and dying young: life history and ecology of a Neogene sperm whale. Journal of Vertebrate Paleontology, 38(2), e1439038. [2] Voss, M., Antar, M. S. M., Zalmout, I. S., & Gingerich, P. D. (2019). Stomach contents of the archaeocete Basilosaurus isis: Apex predator in oceans of the late Eocene. PloS one, 14(1), e0209021. |
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Post by Life on Oct 24, 2019 20:18:38 GMT 5
I have seen some people claim 24m, 130 tonnes Livyatans scaling up from theropod1’s Livyatan estimates to the McLain size estimation of a sperm whale (24m) and claiming it was a giant orca essentially, with abilities of tool use due to its large brain (lol). Essentially what Grey was saying I definitely see more awesomebro minsinformed calculations of Livyatan in the future, I wouldn’t be surprised if they scales it to 30m claiming it was “how big sperm whales in the past used to be” (referring to dubious whaling records). Then I also notice them “””mistaking”” 10m as a hard maximum for the shark. Livyatan is overhyped in order to make it more “awesome” than the shark such as what happened with JP3 Spinosaurus killing the T Rex to show how powerful it was. Unfortunately a very large amount of people thinking a Megalodon vs Livyatan is the same as a Great White vs Orca. Yes there are definitely Megalodon fanboys citing the 20m 103 tonnes size figure, but in general the public and online Livyatan definitely is more overhyped. I’m not a hundred percent sure about real paleontologists thoughts on this...Many are fangirls of cetaceans actually.
Take this publication for instance: Raptorial sperm whales of the genus Livyatan were described from the Miocene of Peru and Chile. Revision of paleontological collections resulted in the finding of isolated teeth belonging to aff. Livyatan sp. coming from Early-Middle Miocene strata from Bajo del Gualicho area, Río Negro Province, Argentina. These specimens represent the first finding of this genus in the Southwestern Atlantic Ocean and indicate that Livyatan-like forms were more widespread than previously thought. The reasons of the extinction of such predatory whales are still uncertain, but it is not improbable that it may be correlated with competition for food resources with globicephaline delphinids. This hypothesis still rests on weak evidence and should be evaluated through findings of new specimens, as well as detailed analysis of the fossil record. [1][1] PIAZZA, D. S., AGNOLIN, F. L., & Lucero, S. (2019). FIRST RECORD OF A MACRORAPTORIAL SPERM WHALE (CETACEA, PHYSETEROIDEA) FROM THE MIOCENE OF ARGENTINA. Revista Brasileira de Paleontologia, 21(3), 276-280. You see that? DELPHINIDSAs if these authors didn't knew about Megalodon.... |
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Post by sam1 on Oct 24, 2019 20:24:55 GMT 5
1 You're asking me why a species will have trouble evolving next to a supposedly supreme and dominant species that already occupies the same place in the ecosystem? What happened to the enormous pressure it has to face to evolve as such in the first place? 2) I addressed that in the above post. there's NO WAY a relatively blunt tooth will leave a clearly identifiable trace on a tooth several times smaller than it. 3) I really have doubts that a giant hypercanivorous whale can evolve locally. Especially if it was a social creature(which was likely imo). The large prey demands would be unparalleled. Also, teeth found in Australia are almost certainly of the livyatan type, is that cosmopolitan enough for you? 4) erm... Here's a story..stem physeteroids actually SURVIVED. Unlike megalodon. They adapted. They are still thriving, in their modern form! Time to address your queries and misconceptions. Massive radiation of baleen whales in Miocene due to environmental factors (20 - 5 Ma range): [1]- is believed to have facilitated emergence of Livyatan-types in Miocene (13.8 - 11.6 Ma range): [2]NOTE: Gigantic Livyatan-types (e.g. Livyatan melvillei) seem to replace Orca-types (e.g. Brygmophyseter shigensis) in the Southern hemisphere around 13.8 Ma mark. However, baleen whales were becoming larger over time: [3]Bigger Baleen whales were harder to kill accordingly?ORCompetitive pressures from 'gigantic sharks' proved too much. TAKE YOUR PICK To give you some perspective, take a look at lifespans of stem physeteriods in the Northern hemisphere (Lee Creek sector): [2]"Life history can provide substantial insight into the ecology of a taxon. Given that all that remains of physeteroids from Lee Creek Mine is largely teeth, any information to be gleaned from teeth about their place in the mid-Atlantic Pliocene ecosystem will be valuable. The similarity of life history inferred for our extinct physeteroid to that of D. leucas, the beluga whale, discussed above might prove helpful in this regard. The rapid growth, early maturation, and relatively short life span of both taxa could arise from a similar selective pressure. Although fairly large animals themselves, belugas are ecologically quite distinct from other large odontocetes in that they experience significant predation from polar bears and more commonly killer whales (Brodie, 1971; Shelden et al., 2003). Roff (2002) and Brown and Sibly (2006) recognize extrinsic mortality as a key influence on life history strategy. When resources are not limiting but extrinsic mortality is high, a fast life history strategy offers a distinct advantage—individuals genetically predisposed to growing fast and reproducing early have a higher fitness than others, and the population shifts over time toward individuals with those traits (Stearns, 1992). High predation pressure driving fast growth and early maturation is linked to shorter life spans (Huang et al., 2008), because senescence begins after the initiation of reproduction. Early maturation has been linked to high extrinsic mortality in a number of taxa (e.g., Charnov, 1990; Stearns, 1992; Migliano et al., 2007; de Magalhaes and Costa, 2009; Ricklefs, 2010). Phocoenids such as the harbor porpoise, for example, include some of the fastest-maturing and shortest-lived odontocetes (Van Utrecht, 1978), and they experience high extrinsic mortality attributed to predation by sharks and killer whales (Jefferson et al., 1991; Long and Jones, 1996) and to direct competition from delphinids (Ross and Wilson, 1996). Interestingly, extant kogiids, although much smaller than these Pliocene relatives, also exhibit unusually early maturation and short life spans for their size. Like the phocoenids, these traits are attributed to high predation pressure (Plon, 2004), suggesting an ecological if not an evolutionary link with the Lee Creek physeteroids." [2]---Your argument about Livyatan melvillei being the ULTIMATE PREDATOR of Neogene is contingent upon "colorful assumptions in large part." Heck, I provided evidence of a Megalodon taking good care of a Livyatan-type whale in the Northern hemisphere: REFERENCES[1] Marx, F. G., & Fordyce, R. E. (2015). Baleen boom and bust: a synthesis of mysticete phylogeny, diversity and disparity. Royal Society Open Science, 2(4), 140434. [2] Gilbert, K. N., Ivany, L. C., & Uhen, M. D. (2018). Living fast and dying young: life history and ecology of a Neogene sperm whale. Journal of Vertebrate Paleontology, 38(2), e1439038. [3] Pyenson, N. D. (2017). The ecological rise of whales chronicled by the fossil record. Current Biology, 27(11), R558-R564. Grey elosha11 theropod Alright.. Like I noted on occasions(and you had jo problem agreeing with it), megalodon was a better, much more efficient whale killer. I also noted that livyatan probably had to rely on overpowering the prey, which is a problematic strategy if the prey becomes too big or too fast. There's no way for livyatan to easily kill a sei or a right whale type(the one being too fast, the other too strong and durable) of prey..both will be way too energy costly. Otoh, a pod of whale killing livyatans will have even bigger issues. To survive, they'd need an enormous amount of meat per day. So yeah, if whales indeed got bigger and faster, I see stem physeters having to change their game and go for an easier prey..I e. like noted already - adapting and evolving into specialized deep sea hunters where prey is abundant, and easy to kill. All perfectly logical, and fits into place. But of course, why would I follow logic when I can just see it was all due to the mighty megalodon? |
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Post by Grey on Oct 24, 2019 21:11:42 GMT 5
Theropod, here is the original drawing of the 11.37 m (290 cm UJP) model.  This means the original jaws of 433.5 cm UJP scaled at 17 m TL corresponds to a 19.5 m TL using our dataset. |
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Post by Life on Oct 24, 2019 21:17:47 GMT 5
Alright.. Like I noted on occasions(and you had jo problem agreeing with it), megalodon was a better, much more efficient whale killer. I also noted that livyatan probably had to rely on overpowering the prey, which is a problematic strategy if the prey becomes too big or too fast. There's no way for livyatan to easily kill a sei or a right whale type(the one being too fast, the other too strong and durable) of prey..both will be way too energy costly. Otoh, a pod of whale killing livyatans will have even bigger issues. To survive, they'd need an enormous amount of meat per day. So yeah, if whales indeed got bigger and faster, I see stem physeters having to change their game and go for an easier prey..I e. like noted already - adapting and evolving into specialized deep sea hunters where prey is abundant, and easy to kill. All perfectly logical, and fits into place. But of course, why would I follow logic when I can just see it was all due to the mighty megalodon? WE are making progress! Good. Now, whatever happened to ram-disabling power of Livyatan melvillei? Or biting off fins and/or flippers? This is why I have cautioned against over-reliance on COLORFUL IMAGINATIONS to evaluate Livyatan's chances against an adult Megalodon in a one-on-one encounter. WE DO NOT KNOW. If Livyatan had trouble taking on a large baleen whale (which might be the case), it had even less of a chance against an adult Megalodon in a potential one-on-one encounter (logical inference). WE do have WH023 to consider - an observation. Given the trophic levels for which Livyatan was seemingly contesting, only gigantic sharks were large, powerful and aggressive enough to give it a run for its money. One party had to give up, and it wasn't Megalodon. Of-course, additional factors could be at play as well because causes of extinction are never so cut and dry. However, WE can continue to admire Livyatan for the BEAST it was - beautiful; majestic; and intimidating. One of the most powerful.If somebody ask me a question that which epoch I would consider to be most dangerous in terms of stepping into waters - I would say MIOCENE. Too many macropredators and opportunities lurking beneath the waves. |
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Post by dinosauria101 on Oct 24, 2019 21:22:47 GMT 5
If somebody ask me a question that which epoch I would consider to be most dangerous in terms of stepping into waters - I would say MIOCENE. Too many macropredators and opportunities lurking beneath the waves. Wouldn't it be the Jurassic or Cretaceous? The Miocene predators may have been more formidable, but the Jurassic and Cretaceous seas were loaded with many, many more types of predator - plesiosaurs, pliosaurs, sharks, Xiphactinus, mosasaurs, marine crocodiles, ichthyosaurs, and teleosaurids - in the seas all at once during the Jurassic and Cretaceous, as opposed to just Livyatan and Megalodon in the Miocene. |
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Post by sam1 on Oct 24, 2019 22:06:40 GMT 5
Alright.. Like I noted on occasions(and you had jo problem agreeing with it), megalodon was a better, much more efficient whale killer. I also noted that livyatan probably had to rely on overpowering the prey, which is a problematic strategy if the prey becomes too big or too fast. There's no way for livyatan to easily kill a sei or a right whale type(the one being too fast, the other too strong and durable) of prey..both will be way too energy costly. Otoh, a pod of whale killing livyatans will have even bigger issues. To survive, they'd need an enormous amount of meat per day. So yeah, if whales indeed got bigger and faster, I see stem physeters having to change their game and go for an easier prey..I e. like noted already - adapting and evolving into specialized deep sea hunters where prey is abundant, and easy to kill. All perfectly logical, and fits into place. But of course, why would I follow logic when I can just see it was all due to the mighty megalodon? WE are making progress! Good. Now, whatever happened to ram-disabling power of Livyatan melvillei? Or biting off fins and/or flippers? This is why I have cautioned against over-reliance on COLORFUL IMAGINATIONS to evaluate Livyatan's chances against an adult Megalodon in a one-on-one encounter. WE DO NOT KNOW. If Livyatan had trouble taking on a large baleen whale (which might be the case), it had even less of a chance against an adult Megalodon in a potential one-on-one encounter (logical inference). WE do have WH023 to consider - an observation. Given the trophic levels for which Livyatan was seemingly contesting, only gigantic sharks were large, powerful and aggressive enough to give it a run for its money. One party had to give up, and it wasn't Megalodon. Of-course, additional factors could be at play as well because causes of extinction are never so cut and dry. However, WE can continue to admire Livyatan for the BEAST it was - beautiful; majestic; and intimidating. One of the most powerful.If somebody ask me a question that which epoch I would consider to be most dangerous in terms of stepping into waters - I would say MIOCENE. Too many macropredators and opportunities lurking beneath the waves. No, we've already established the difference between killing and fighting. Need I remind you that you yourself stated that Livyatan might've been a better fighter? It's all about the whole picture, and you again and again revert this to the basic biting contest. Megalodon could simply bite a bigger chunk out of the whale faster than s livyatan can. That's all, and all(well, except for the stalking capability assuming that Livyatan lived in pods which would make it terrible at being an ambush killer) that makes him a better whale killer than livyatan is..it doesn't make livyatan incapable of killing a whale. And it doesn't make megalodon a favorite in an all out fight between the two. |
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Post by Life on Oct 24, 2019 22:15:29 GMT 5
If somebody ask me a question that which epoch I would consider to be most dangerous in terms of stepping into waters - I would say MIOCENE. Too many macropredators and opportunities lurking beneath the waves. Wouldn't it be the Jurassic or Cretaceous? The Miocene predators may have been more formidable, but the Jurassic and Cretaceous seas were loaded with many, many more types of predator - plesiosaurs, pliosaurs, sharks, Xiphactinus, mosasaurs, marine crocodiles, ichthyosaurs, and teleosaurids - in the seas all at once during the Jurassic and Cretaceous, as opposed to just Livyatan and Megalodon in the Miocene. BBC rankings are based on incomplete information and/or understanding. MIOCENE macropredators at a glance:- Megalodon Carcharocles chubutensis Isurus hastalis Hemipristis serra Livyatan melvillei Acrophyseter deinodon Eudelphis mortezelensis Squalodon / similar Purussaurus Megapiranha paranensis / similar To name a few. There were variations throughout Miocene of-course. |
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Post by dinosauria101 on Oct 24, 2019 22:22:23 GMT 5
Wouldn't it be the Jurassic or Cretaceous? The Miocene predators may have been more formidable, but the Jurassic and Cretaceous seas were loaded with many, many more types of predator - plesiosaurs, pliosaurs, sharks, Xiphactinus, mosasaurs, marine crocodiles, ichthyosaurs, and teleosaurids - in the seas all at once during the Jurassic and Cretaceous, as opposed to just Livyatan and Megalodon in the Miocene. BBC rankings are based on incomplete information and/or understanding. MIOCENE macropredators at a glance:- Megalodon Carcharocles chubutensis Isurus hastalis Hemipristis serra Livyatan melvillei Acrophyseter deinodon Eudelphis mortezelensis Squalodon / similar Purussaurus Megapiranha paranensis / similar To name a few. There were variations throughout Miocene of-course. How do you know where I got that from? You must be psychic. Well, should be similar to the Late Jurassic predators as follows: -Hybodus -Dakosaurus -Liopleurodon -Pliosaurus (12 species!) -Metriorhynchus -Machimosaurus -Simolestes -Torvonuestes -Geosaurus -Purranisaurus -Bathysuchus -Tyrannonuestes -Teleosaurus -Opthalmosaurus Or these Late Cretaceous ones: -Tylosaurus -Deinosuchus -Mosasaurus -Prognathodon -Cretoxyrhina -Hybodus, again -Megacephalosaurus -Elasmosaurus (yes, really) -Xiphactinus -Globidens -Dallasaurus -Dolichorhynchops Overall, the Jurassic and Cretaceous seems a bit more dangerous. One thing's for sure though; I would NOT like to go swimming at any of them |
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Post by Life on Oct 24, 2019 22:44:18 GMT 5
No, we've already established the difference between killing and fighting. Need I remind you that you yourself stated that Livyatan might've been a better fighter? It's all about the whole picture, and you again and again revert this to the basic biting contest. Megalodon could simply bite a bigger chunk out of the whale faster than s livyatan can. That's all, and all(well, except for the stalking capability assuming that Livyatan lived in pods which would make it terrible at being an ambush killer) that makes him a better whale killer than livyatan is..it doesn't make livyatan incapable of killing a whale. And it doesn't make megalodon a favorite in an all out fight between the two. So WE are back to square one again? No wonder this discussion have exceeded 100 pages. I have provided the BIGGER PICTURE to you, today. What I stated earlier, was based on limited information. I can see better now after piecing together numerous bits and pieces of information to achieve a better understanding of Livyatan and its implied competitiveness. And the bigger picture doesn't bode well for assumptions about macrophagous capabilities of Livaytan melvillei from any perspective. If Livyatan was struggling to subjugate large baleen whales (9m and above in TL) with brute force on a regular basis then its macrophagous capabilities are suspect as well as it being a better fighter in comparison to Megalodon. Great white sharks can find it easier to ambush other animals because they are puny in comparison to Megalodon; small size make it possible for the great whites to escape attention even in shallow water environments. However, Megalodon is likely to turn some heads with its movements even from a distance, and cetaceans had echolocation back then. Ambushing whales would not be possible each time, and in every manner of setting. Brute force would come into play at some point and there is fossil evidence of Megalodon aiming for the chest cavity or even the skull of a cetacean in order to kill it swiftly. Livyatan cannot be superior to Megalodon in fighting and still struggle to subjugate large baleen whales and/or cetaceans in general - OXYMORON. I do not rule out the possibility of Livyatan being able to kill a large baleen whale and/or animal [in general] in person but WE need to consider the BIGGER PICTURE here. Refer back to observations in this post: theworldofanimals.proboards.com/post/48590--- A heavyweight champion would subdue a lesser opponent in a fight - no ifs and buts. This is why WWE is FAKE, and cruiserweight boxers are not allowed to get in the ring with heavyweight boxers. |
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Post by theropod on Oct 24, 2019 23:26:38 GMT 5
Fossil record of ancient sperm whales = very rich Fossil record of ancient sharks = very rich "very rich" is a bit of an overstatement. Consider that almost all the macroraptorial physeteroids ( Brygmophyseter, Zygophyseter, Acrophyseter, Livyatan, were only first described in the last 3 decades, this gives an idea of the incompleteness of the fossil record. One needs to be very careful about drawing palaeogeographical conslusions from that. But as I already wrote, based on current evidence I agree that Livyatan may have been antitropical and restricted to the southern hemisphere. The fact that Livyatan-types do not appear to be widespread (limited to Southern hemisphere) even in the Miocene (a relatively stable epoch), does not bode well for 'assumptions' in this thread that these cetaceans were peers of Megalodon in big-game hunting and/or otherwise. It likely has nothing to do with it at all. Do you think the absence of Polar bears in the Amazon rainforest is due to jaguars being the more formidable apex predator? Really, this reduction of of all ecological and biogeographical matters to "this taxon beats this taxon in a fight" is puzzling to me, as this is just absurd from a biological point of view. The reason for this likely has nothing to do with megalodon at all. Again, how do you know? This is exceedingly bold statement. On the contrary, that is an exceedingly parsimonious statement. Environmental and climatic conditions are by far the better explanation, especially considering it seems to have successfully coexisted with megatooth sharks in the southern half of the latter’s range. Nobody is making the claim that C. megalodon was the only animal that had to face competition, on the contrary, I can assure you that all biologists are well aware competition is a widespread phenomenon. In fact, Megalodon had necessary adaptations to not only cope with these pressures but to anchor itself to the top of the food chain(s) in any environment it inhabited (gigantism; regional endothermy; superb killing apparatus; robust physiology - you name it). One can make those points for Livyatan as well, but I don’t see their relevance to the issue, that competition with megalodon was supposed to be the reason why Livyatan was (based on current fossil record) not found in the northern hemisphere.
No, not a belief. Referred Livyatan sp. teeth from the early Pliocene of South Africa (Govender et al. 2019) and Pliocene giant physeteroid teeth from the Pliocene of Melbourne suggest that Livyatan existed at least for several millions of years, since the holotype is Tortonian in age.
There are no miocene fossil localities from Antarctica as to my knowledge, so once more, are you asking for impossible evidence here? But isotopic ratios in the one specimen studied suggest it lived at palaeolatitudes greater than 40°, certainly not polar (let alone really cold, it is the Miocene we are talking about), but by no means tropical. It is of course a little early to draw any conclusions. It is also to early to conclusively rule out Livyatan may have existed in the northern hemisphere as well.
There are many cetacean species with antitropical distributions, as I am sure you are aware.
WH023 suggests that an indeterminate large physeteroid (carcass?) was at some point (possibly) bitten by a shark, nothing more, nothing less.
Because isolated Physeteroid teeth are not necessarily diagnostic at the genus level, and because. If we consider every large Physeteroid tooth to be from Livyatan, then there’s also a record of the taxon from the Netherlands (Reumer et al. 2017)… Err no, they don’t. Most stem-physeteroids are probably more in the 5-7 m range. But how is that relevant? Also, what do the stem-physeteroids studied by Gilbert et al. have to do with that?
The genus Livyatan is an outlier in size for stem physeteroids. Just like megalodon is an outlier in size for lamniforms. Your point being…?
It is utterly unusual…and still not evidence of predation.
Yes, so?
Megalodon "tearing through the jaw structure of a stem-physeteroid" is certainly possible. It tore through 6 m cetotheres, so presumably it could have torn through 6 m physeteroids. Tearing through the jaw structure of a Livyatan-sized physeteroid is a lot less plausible. That being said, this is clearly not necessary to have left a bite mark like that on the tooth.
There is no evidence of a juvenile megalodon "breaching the chest cavity" of a large whale whatsoever. In case you are referring to the cetacean rib described by Kallal et al., it bears callouses interpreted as healed bite marks on the outside of the rib.
A bite that very clearly came nowhere near "breaching the chest cavity".
Nevertheless, a very impressive case of predation indeed, I agree.
I thought I had made it clear in discussions with member Grey that I am not overly amused by such strawmen and baseless insinuations of bias? I think such behaviour poisons the debate culture here.
Yes. All of them with other osteognathostomes with bony skeletons that actually show up in the fossil record, not chondrichthyans that do not. As for stomach contents, how are you expecting to find stomach contents of an animal with no known postcranial remains?
May I respectfully suggest that, presumably having participated in quite a few more fossil excavations, and handled quite a few thousand more fossils than you, I have some degree of experience of what kind of marks can be left by excavation tools?
As I said it is possible (that is not an assumption, merely an expectation) that during the two previous centuries, pathologies or trace fossils on other cetaceans caused by raptorial physeteroids (that as I pointed out were not yet known to be a candidate) could have been commonly attributed to megalodon, or not necessarily recognized as bite marks (that is an assumption, but not on my part). Apart from that, nothing.
But had you asked me to show you evidence of a 15 m raptorial physeteroid 10 years ago, there would have been no such evidence either, that wouldn’t have made concluding that it did not exist any more correct.
Well, other members here appear to be going so far as to claim that megalodon could dominate an adult Livyatan in a one-on-one encounter. Both seem about equally outrageous or "hyped" to me.
I’m not sure if I or anyone else has actually suggested that, but I think I made it clear that we are data-deficient when it comes to the ecology of Livyatan, which hopefully future studies will help us with.
I think I have posted quite a wealth of evidence for Livyatan’s size, killing apparatus and implied physical attributes on this thread and elsewhere on this board, in fact I have almost entirely focused on doing so, rather than spending my time entertaining pointless speculations about who wins in a fight. In some regards, more than we have for megalodon. But as I already wrote, absence of evidence is not evidence of absence. Again, we didn’t even know Livyatan even existed 10 years ago, it is quite unjustified to conclude from not knowing any cases of bite marks left by it that it didn’t ever produce any, especially since I have already named additional reasons why Livyatan bite marks might not be recognized as such.
I fail to follow you here. Brygmophyseter (why "orca-types"?) isn’t just contemporaneous with Livyatan, it is also not from the southern hemisphere, and there is no sign whatsoever that Livyatan "replaced" it or other smaller stem-physeteroids in the southern hemisphere, in fact it coexisted with at least two species in the Pisco formation alone (Lambert et al. 2016).
How about "Neither"?
Livyatan and Megalodon may well have gone extinct at about the same time (at some point during the Pliocene). Boessenecker et al. 2019 suggest a lower Pliocene extinction for Megalodon, which coincides with the youngest currently described Livyatan teeth. Pimiento et al. 2016 suggested an upper pliocene extinction, but the sample for Livyatan is insufficient to be sure whether it survived into the upper pliocene (we don’t even have precise provenance data for all specimens, the teeth from the Bahia Inglesa Formation could be anything between Upper Miocene and Upper Pliocene. Underlying causes are still not entirely clear, but in my experience, climate change is usually involved in some way when animals go extinct, as are biological factors, or often some combination of the two.
Life spans and their implications for predation pressure in smaller, <10 m physeteroids (the Lee Creek Mine teeth are comparable in size or smaller than those of Brygmophyseter and Zygophyseter, so most likely their owners were more like 5-7 m than 8-10) is about as relevant to the ecology of Livyatan as a great white shark’s are to megalodon’s.
I don’t get your meaning here either. As if it weren’t bad enough that you are calling scientific researchers "fangirls" (?? besides none of the authors of that study appears to be a woman…), there is nothing fanboyish or even mildly sensationalistic about that study.
An important quote from the same paper, pertaining to our earlier point of contention
References: Boessenecker, R.W., Ehret, D.J., Long, D.J., Churchill, M., Martin, E. and Boessenecker, S.J. 2019. The Early Pliocene extinction of the mega-toothed shark Otodus megalodon: a view from the eastern North Pacific. PeerJ 7: e6088.
Gilbert, K.N., Ivany, L.C. and Uhen, M.D. 2018. Living fast and dying young: life history and ecology of a Neogene sperm whale. Journal of Vertebrate Paleontology 38 (2): e1439038. Govender, R. 2019. Early Pliocene fossil cetaceans from Hondeklip Bay, Namaqualand, South Africa. Historical Biology: 1–20.
Kallal, R.J., Godfrey, S.J. and Ortner, D.J. 2012. Bone reactions on a pliocene cetacean rib indicate short-term survival of predation event. International Journal of Osteoarchaeology 22 (3): 253–260.
Lambert, O., Bianucci, G. and De Muizon, C. 2016. Macroraptorial sperm whales (Cetacea, Odontoceti, Physeteroidea) from the Miocene of Peru. Zoological Journal of the Linnean Society 179 (2): 404–474.
Piazza, D.S., Agnolin, F.L. and Lucero, S. 2019. First record of a macroraptorial Sperm Whale (Cetacea, Physeteroidea) from the Miocene of Argentina. Revista Brasileira de Paleontologia 21 (3): 276–280. Reumer, J.W.F., Mens, T.H. and Post, K. . New finds of giant raptorial sperm whale teeth (Cetacea, Physeteroidea) from the Westerschelde Estuary (province of Zeeland, the Netherlands). : 7. Pimiento, C. and Clements, C.F. 2014. When Did Carcharocles megalodon Become Extinct? A New Analysis of the Fossil Record. PLOS ONE 9 (10): e111086.
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Post by Grey on Oct 24, 2019 23:45:29 GMT 5
Boessennecker's paper about megalodon's extinction mentions killer sperm whales go extinct earlier than meg.
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