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Megalodon not as big as we once thought!
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Interesting discussion in response to Perez's 2021 publication that dealt with Lamniform body size estimates.
https://twitter.com/Dinoh555/status/1370043407041724420  (01-23-2022, 06:47 AM)Ediacaran Wrote: Interesting discussion in response to Perez's 2021 publication that dealt with Lamniform body size estimates. And this is what happened with Megalodon during all these years! One people put a paper with an estimation, latter other people shows that is incorrect, other put other paper and latter is debunked. The size of this shark is very problematic as there are only teeth and a very few vertebrae that managed to be fosillize. The conversation is very interesting and try to refute those estimations. Using Cretolamna, they propose a maximum size of 13.2 m and 20 tones for the largest known tooth by scientists and of 14.6 m and 27 tones for the largest tooth in private record. Of course this are just the estimations of a few posters there, but they suggest that the work of Dr Shimada is more reliable. Who knows what will say the next document about this giant shark.......
Hi, I'm one of the co-author of the 2021 lamniform body size study.
The people discussing Perez et al. 2021 article in these tweets argue about the variant phylogeny between otodontids and lamnids but curiously use methods that are based on Gottfried 1996 (vertebra diameter) and Shimada 2019 (crown height), both methods using as a proxy... Carcharodon carcharias. So their critics were quite premature and they probably did not have scrutinized the article anyway. They also ignore that the authors did consider using Cretalamna Summed Crown Width to get a TL estimate for Otodus megalodon but it was simply far too much for a single paper as they had already a sample of modern associated sets of teeth from Carcharodon and Isurus, a sample larger than the one used by Shimada for his own method anyway. They should simply use Cretalamna associated teeth and use our method on it and publish, that would be interesting. I also advise to check Jack Cooper's on going research, https://youtu.be/X4FA45QwlIA Otodus megalodon was probably not as small as some seem to wish on this thread. 
Megalodon size limit has been established to be around 20 meters long for a freaklish outlier female
(02-07-2022, 11:08 PM)GuateGojira Wrote:(01-23-2022, 06:47 AM)Ediacaran Wrote: Interesting discussion in response to Perez's 2021 publication that dealt with Lamniform body size estimates. (06-26-2022, 02:12 AM)AndresVida Wrote: Megalodon size limit has been established to be around 20 meters long for a freaklish outlier femaleGHC-6 is absolutely not an outlier, comparable teeth exist in other museums, privates or not, including the London one. Using the same method MNHN CP62 belongs to a 19.9-21.7 m individual from Chile in the data from Shimada 2022 Supp Material about body size trends (see attached) ~20 m is a good benchmark for max sized cold water inhabiting female O. megalodon but teeth comparable or even slightly larger than GHC-6 do exist in private collections and in some museums through the world. (06-26-2022, 03:02 PM)Semyon Wrote: 20 m is a good benchmark for max sized cold water inhabiting female O. megalodonThat's all about it, consider the fact that some megalodons could have just had a proportionally slightly larger teeth that just belongs to a megalodon that is the same size about GHC-6 and has no significant size difference rather than a few cm as no animal of any species has the same proprortions of others I also doubt the cold water / warm water size difference among these sharks since you quoted that "cold water" topic which is probably referred to that recent study claiming that Megalodons inhabiting cold waters grow larger than their warm water counterparts. I mean, sharks are Migratory animals and the cold water Megalodons are just subadult Megalodons that may have migrated upwards while maturing from the south, like they'd go to South to reproduce and then go back towards the north. I've made a size comparison related to that study showing the max sizes of warm and cold water megalodon females with a max sized livyatan just for scale  *This image is copyright of its original author And yes, GHC-6 is an outlier. Any individual of any animal species reaching or surpassing what is considered to be the general max size barrier of that animal species is automatically an outlier. Leopards that reach or surpass 90 kgs are outliers, just like megalodons that reach or surpass 20 meters in length (02-07-2022, 11:08 PM)GuateGojira Wrote:(01-23-2022, 06:47 AM)Ediacaran Wrote: Interesting discussion in response to Perez's 2021 publication that dealt with Lamniform body size estimates. (06-26-2022, 06:13 PM)AndresVida Wrote:(06-26-2022, 03:02 PM)Semyon Wrote: 20 m is a good benchmark for max sized cold water inhabiting female O. megalodonThat's all about it, consider the fact that some megalodons could have just had a proportionally slightly larger teeth that just belongs to a megalodon that is the same size about GHC-6 and has no significant size difference rather than a few cm as no animal of any species has the same proprortions of others Of course some individuals could have obviously proportional larger teeth, this is constant once we extrapolate to very large size, the point is GHC-6 is not an outlier because there are other teeth comparably sized from various parts of the world even available to museums, so 20 m is a natural max size for cold water megs. There are more than one shark approaching 20 m using Perez method in the file I sent you. So nothing such as an outlier. Yes the 2022 cold water article by Shimada would need a larger sample but it is nothing new in that it has been remarked since a long that meg teeth from temperate waters appeared on average larger. An outlier is an individu (06-26-2022, 11:43 PM)Semyon Wrote: the point is GHC-6 is not an outlier because there are other teeth comparably sized from various parts of the world even available to museums, so 20 m is a natural max size for cold water megs.You seem remarkably confused about the definition of "outlier" in this context despite the fact that I have highlighted in black the sentence that removes all doubts about it. "Outlier" refers to something "anomalous", out of the ordinary and out of the ordinary and consequently in the world of animals any individual who is significantly larger than the average of the species is considered as "exceptionally large". Obviously you think that outlier refers only and exclusively to an envied person who is the greatest of all but no, it doesn't work like that. Since "outlier" means "anomalous, exceptionally large" any megalodon that reaches or allegedly exceeds what is considered the maximum size of the species is considered "outlier". Therefore, there can be more than one outlier. GHC-6 is, therefore, an outlier since it is estimated to have reached the maximum length for a megalodon. Obviously there can be more than one outlier, I always give the example of leopards because it is convenient for me: 90-100 kg is considered the maximum barrier for these cats and we have some that have overcome it. -90.72 kg male from Kruger -91 kg male from Iran -92.5 male from Aberdares -95 kg male from Khomas Regions in Namibia -96.5 male from Valencia, Namibia - 96 kg male shot on the aberdare mountaina in the 1960s - c. 98 kg Male from North Iran + an unconfirmed 90+ kg Vin diesel and an alleged 108 kg baited Namibian leopard that probs weighed between 90 - 100 kg empty All of these leopards are outliers since they reached what is considered to be the benchmark for the size limit of this species. The same applies to Megalodon, ghc-6 is an outlier, but this doesn't mean that there can't be other outliers of the same or maybe even slightly bigger size. Any megalodon of 20 m long is an outlier, aka "exceptionally large". And of course, more than 1 megalodon surely reached this size. Outlier =/= largest individual ever Outlier = any individual that reaches what is considered to be the max size
Check again the data from Shimada 2022 I linked above, note the TL estimates using the SCW method and tell us if the various ~20 m estimates appear to be outliers to you, especially inside a single population. Today a 5.9 m white shark is not an outlier, a 7 m one is. An outlier is the 24 m male Physeter in a sample of 500 000 (McClain 2015). GHC-6 is certainly not as exceptional as this, especially when taking into account the regional size differences (Pimiento 2015, Shimada 2022).
The 20 m data in Perez et al. is itself somewhat conservative being the mean of the range (17.4-24 m) and using the lowest regression available here. (06-27-2022, 07:31 PM)Semyon Wrote: An outlier is the 24 m male Physeter in a sample of 500 000 (McClain 2015). GHC-6 is certainly not as exceptional as this, especially when taking into account the regional size differences (Pimiento 2015, Shimada 2022).20,3 was actually the alleged mean of such range, but the same study mentioned that the 24 m long estimate is an exagerration derivied from error (very common when you have one of the most fragmentary animals on the planet of which you don't know it's true proportions and the rest is just nice speculation)  *This image is copyright of its original author Source : https://www.researchgate.net/publication...dentitions I don't buy 24 meters either, 19 - 20 m seems more reasonable. And yes, even if the 24 meters long estimate is real, ghc-6 would still be an outlier since it is crossing the max reported size range of megalodon just quoted at 19 - 20+ meters. It doesn't matter if there might be an even larger individual out there, always using the leopard example a 91 kg leopard is an outlier just like the 98 kg male from north Iran since both have reached the max reported size of this species. So no matter if there's an even 24 meters long megalodon out there, any megalodon reaching the max reported size is therefore an outlier specimen. For a female cold water Otodus Megalodon offhand 13-14 m would be below average probably immature or exceptionally small females 15 - 16 m would be average 17 - 19 m would be large 20+ meters would be exceptionally large where the largest specimens (aka outliers) can be found (02-07-2022, 11:08 PM)GuateGojira Wrote:(01-23-2022, 06:47 AM)Ediacaran Wrote: Interesting discussion in response to Perez's 2021 publication that dealt with Lamniform body size estimates. (06-28-2022, 10:34 AM)AndresVida Wrote:(06-27-2022, 07:31 PM)Semyon Wrote: An outlier is the 24 m male Physeter in a sample of 500 000 (McClain 2015). GHC-6 is certainly not as exceptional as this, especially when taking into account the regional size differences (Pimiento 2015, Shimada 2022).20,3 was actually the alleged mean of such range, but the same study mentioned that the 24 m long estimate is an exagerration derivied from error (very common when you have one of the most fragmentary animals on the planet of which you don't know it's true proportions and the rest is just nice speculation) I'm actually quite agreed, but you certainly jump to premature conclusions as no new global review of size distribution in Otodus using the newer SCW method has been done yet. It is not impossible that we underestimate a bit the size of the Otodus genus, the backbone from Belgium was estimaged using centra diameter (155 mm) compared to white shark centra that it came from a 9.21 m megalodon (Gottfried 1996, Shimada 2019) however work by Catalina Pimiento and on going work by Jack Cooper indicates the Belgian backbone is actually 11.1 m on its own, almost 2 m longer than the previous estimate for the whole shark. Cooper article should come out soon, but there is this talk last year https://youtu.be/X4FA45QwlIA Spoiler : they estimate the whole shark (adding chondocranium and caudal) at 15.93 m. As you see in the talk, this seems to confirm to solidity of the SCW method over Shimada's equation. Using this, the largest reported megatooth centra in the literature is from some Danish material, today unfortunately discarded, described in Bendix-Almgreen (1983) as 23 cm in diameter. Simple scaling from the Belgian 11.1 m backbone gives in a 16.5 m long backbone so the correspondingly whole animal.. But before arguing about anything I'd prefer to wait to see the feedback on Cooper's article, as well as we'd need an updated size distribution review for the genus. Again by outlier I meant a freak, a 20 m bull sperm whale is not a freak to me, the purpoted 24 m male from McClain's review would be. As the SCW method proposes several 18-20 m individuals in Shimada 2022, 20 m does not make it the Robert Wadlow of the genus. I don't buy firmly the 24 m bull Physeter from McClain but the report seems relatively reliable and being the longest individual among 500 000 would make it an normal outlier, marge jawbones from comparably sized individuals are reported in the literature. Even so, we know that Physeter can physically reach 20.7 m so I would not consider it a freak, just like there is nothing to say Sue and Scotty are freaks on their kin.
The extinct shark Otodus megalodon was a transoceanic superpredator: Inferences from 3D modeling
https://www.science.org/doi/10.1126/sciadv.abm9424 https://theconversation.com/ancient-mega...als-188749 https://youtu.be/SBpIcsrof7M |
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