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Post by theropod on Sept 17, 2019 23:52:53 GMT 5
I cannot find any 6 m, 1.1 t caiman in there the only caiman with any weight figure reported is the 3.5-4m, roughly 300kg one I already quoted, and a couple of smaller ones that weighed a total of 100 kg. The number 6 literally only appears twice in the entire document, neither one referring to a caiman.
I’m not even doubting caimans are heavier at a given length than crocodiles, they definitely have proportionately shorter tails, but we need data to quantify this, and also its potential impact on the total length estimate.
That would give us 11 m assuming it’s DCL, but is it, and was the total length really measured, or was it estimated?
Well no, not really. Obviously I’m not really interested in either, for that very reason, but when you are arguing on the basis of actual characteristics of these animals, these should be based in reality.
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Post by dinosauria101 on Sept 18, 2019 1:21:59 GMT 5
I cannot find any 6 m, 1.1 t caiman in there the only caiman with any weight figure reported is the 3.5-4m, roughly 300kg one I already quoted, and a couple of smaller ones that weighed a total of 100 kg. The number 6 literally only appears twice in the entire document, neither one referring to a caiman. Oh, Wikipedia stated that. That was their citation. Nonetheless, it had to have came from somewhere. I will see what I can find I’m not even doubting caimans are heavier at a given length than crocodiles, they definitely have proportionately shorter tails, but we need data to quantify this, and also its potential impact on the total length estimate. That would give us 11 m assuming it’s DCL, but is it, and was the total length really measured, or was it estimated? Not sure. Will have to check Well no, not really. Obviously I’m not really interested in either, for that very reason, but when you are arguing on the basis of actual characteristics of these animals, these should be based in reality. True |
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Post by theropod on Sept 18, 2019 2:36:24 GMT 5
Do you think you could maybe write your comments outside of the quotebox? Or at least maybe colour them differently or somehow mark them, so it’s clear what’s quoted from me and what’s your comment? There’s no need to rush, take all the time you need for your replies, we’ve got no deadline to meet with this discussion!
And no, just because they are cited, figures don’t necessarily come from somewhere. There are lots of examples of wikipedia articles and even peer-reviewed papers citing stuff that isn’t actually in the source.
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Post by theropod on Sept 20, 2019 2:25:43 GMT 5
Current record holders in terms of length, based on the largest reported specimens: Deinosuchus riograndensis, TMM 43632-1 estimated at 147.5 cm DCL, TL 10.5-11.2 m ¹ { Rhamphosuchus crassidens (largest specimen 11 m according to Head 2001, which is only an SVP abstract, details of estimate unclear, only skull fragments)} Gryposuchus croizati AMU-CURS-58, 140 cm DCL, 10.3 m ³ Purussaurus brasiliensis, DGM 527-R, estimated 134 cm DCL, TL 9.6-10.1 m ¹ Deinosuchus rugosus, ?largest specimen, 131 cm DCL, 9.4-9.9 m ² Sarcosuchus imperator, Largest known skull according to Sereno et al. 2001, 160 cm DCL, 9.8 m ² Purussaurus mirandai, Holotype and largest specimen, ~112 cm DCL, TL 8.1-8.5 m ¹ yet to add: ? Stomatosuchus, Mourasuchus, Crocodylus anthropophagus, Crocodylus thorbjanarsoni? ¹This is using the regression equations for TL from HL (head length) for american alligators from Woodward et al. (±gives 95%CI): exp(2.132494+0.95811*(log(HL))±1.96*(0.0016496-0.000299*(log(HL))+0.0000447*(log(HL)^2))^0.5) exp(2.079667+0.98016*(log(HL))±1.96*(0.0021933-0.000652*(log(HL))+0.0001019*(log(HL)^2))^0.5) HL is estimated as 4.4% larger than DCL (as per Webb & Messel’s measurements of skull and head length in C. porosus), giving us 139.78 cm for Purussaurus, 154.03 cm for DeinosuchusThe Deinosuchus riograndensis specimen is the estimated DCL for a large mandible specimen from Farlow et al. 2005. Farlow et al. also performed a regression of TL vs DCL in Alligators, and their estimate for the Deinosuchus specimen is 10.6 m, within the range estimated here. The Purussaurus brasiliensis specimen is the estimated DCL and HL based on the largest known individual, the 175 cm mandible, based on the ratio between mandible length and DCL in the associated mandible of UFAC 1403 (~122 cm DCL, blaze’s comment on Aureliano et al.), which measures 1595 mm (Aguilera et al.). I haven’t checked up further on the D. rugosus yet, for now I just went with the widely cited 131 cm skull. The P. mirandai is the holotype, with a condylobasal length of 117 cm, as figured by Aguilera et al. it’s DCL would be about 112 cm. ²Based on Terminonaris robusta proportions (6 m TL, DCL 98 cm) from Wu et al. 2001. The Sereno et al. (2001) skeletal reconstruction might suggest Sarcosuchus could have been considerably larger, at a TL of 11.65 m, which would give it the top spot. But let’s stay conservative for now, I will look into this further in the future. ³Estimate from Riff & Aguilera 2008, using the Gharial regression from Sereno et al. 2001.
Aguilera, O.A., Riff, D. and Bocquentin-Villanueva, J. 2006. A new giant Purussaurus (crocodyliformes, alligatoridae) from the upper Miocene Urumaco formation, Venezuela. Journal of Systematic Palaeontology 4 (3): 221–232.
Aureliano, T., Ghilardi, A.M., Guilherme, E., Souza-Filho, J.P., Cavalcanti, M. and Riff, D. 2015. Morphometry, Bite-Force, and Paleobiology of the Late Miocene Caiman Purussaurus brasiliensis. PLOS ONE 10 (2): e0117944.
Riff, D. and Aguilera, O.A. 2008. The world’s largest gharialsGryposuchus: description ofG. croizati n. sp. (Crocodylia, Gavialidae) from the Upper Miocene Urumaco Formation, Venezuela. Paläontologische Zeitschrift 82 (2): 178.
Webb, G.J.W. and Messel, H. 1978. Morphometric analysis of Crocodylus porosus from the north coast of Arnhem Land, Northern Australia. Australian Journal of Zoology 26 (1): 1–27.
Woodward, A.R., White, J.H. and Linda, S.B. 1995. Maximum Size of the Alligator (Alligator mississippiensis). Journal of Herpetology 29 (4): 507–513.
Wu, X.-C., Russell, A.P. and Cumbaa, S.L. 2001. Terminonaris (Archosauria: Crocodyliformes): new material from Saskatchewan, Canada, and comments on its phylogenetic relationships. Journal of Vertebrate Paleontology 21 (3): 492–514.
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Post by dinosauria101 on Sept 20, 2019 2:53:49 GMT 5
theropodSorry, yes I have been a bit busy over the last little bit and these posts do take a bit. I'll respond when I get the chance
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Post by Amaltheus on Sept 22, 2019 12:57:37 GMT 5
Like you already discussed for Sarcosuchus, scaling extinct crocodylomorphs can be a bit tricky. Colleagues of mine (Young et al. 2018) showed for teleosauroids that previous estimates based on recent species were distinctly overestimating their body size. Resulting in the large teleosauroid Machimosaurus rex being downsized from 12 m to 7 m (but still the largest teleosauroid and one the largest thalattosuchians). palaeo-electronica.org/content/pdfs/648.pdfIn terms of paleoecology, we should be also cautious in focussing to much on a hypothetical maximum body size. In a Deinosuchus population most of the adults would be clearly below 10 m in length. In this context a nice take of Mark Witton on the paleobiology of that genus.
markwitton-com.blogspot.com/2016/01/deinosuchus-dalek-backed-alligatoroid.html |
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Post by Infinity Blade on Dec 7, 2019 9:03:11 GMT 5
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Post by Ceratodromeus on Apr 10, 2020 0:43:30 GMT 5
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Post by Infinity Blade on Apr 10, 2020 0:59:11 GMT 5
Hmm, I don't think so. The durophagous lifestyle and bite marks on turtles are consistent from what I remember about this dyrosaurid. The size, not so much, looking at the skull in the paper and the scalebar associated with it (assuming the purported size wasn't way off, which who knows, it could have been).
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Post by Ceratodromeus on Apr 10, 2020 1:10:33 GMT 5
well to be fair, it wouldn't be the first time a prehistoric animals size was overblown in common media websites. I will look to see if i can find anything else that might line up.
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Post by Infinity Blade on Apr 10, 2020 1:17:25 GMT 5
You're definitely right. I'm currently watching a more recent (2016) documentary right now that seems to mention this "Turtle Chomper". I'll see what they say about exact body size for whatever that might be worth.
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Post by Ceratodromeus on Apr 10, 2020 1:22:37 GMT 5
More on Anthracosuchus
A specimen of Anthracosuchus balrogus is prepared next to an alligator skull. (Image credit: Alex Hastings)The comparison is mildly misleading, as i'm pretty sure that's a chinese alligator skull. But still, very neat. www.livescience.com/46046-ancient-croc-lord-of-the-rings-balrog.htmlI'm personally quite confident that this is the animal your article is speaking about, based on the digging i did. |
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Post by Infinity Blade on Apr 10, 2020 1:43:02 GMT 5
Here's the full doc for anyone who wants to have a look. It came out in 2016, so it's more recent than the article I posted and the Monster Snake documentary. www.pbs.org/wnet/secrets/graveyard-giant-beasts-full-episode/3197/EDIT: www.dailymotion.com/video/x5ue8wfBetween the 47:10 to 48:09 marks, they mention that this crocodilian, an owner of a large vertebra, was getting close to adult size and would have measured 8.63 meters long. That's definitely far less than the 40 feet claimed in the 2012 Titanoboa doc, and by no means unbelievable. I think it's possible this could be another still-undescribed taxon that truly did reach the 28 foot mark (though, I feel a lot safer dismissing 40 feet now). Edit: as a side note, I dislike the documentary's model for this dyrosaurid. If it bit into large turtles, then presumably it should have had a very robust skull with a blunt snout, like Anthracosuchus. Its snout looks too much like that of Acherontisuchus in the documentary. |
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Post by Infinity Blade on Aug 17, 2022 14:40:17 GMT 5
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Post by Verdugo on Aug 20, 2022 20:07:14 GMT 5
The estimates for Purussaurus are a bit lower than I though. I recall Brochu & Storrs (2012) pointing out that extrapolation for larger extinct Crocodilian based on a sample size of much smaller modern relatives tends to underestimate the size of larger extinct Crocodilian and that we should add an extra 20% on top of the estimates from the regression. I am wondering if this might have been the case and that the body size estimated here for Purussaurus might have been underestimated. |
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