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Post by theropod on Jun 21, 2013 18:16:35 GMT 5
Yes, Aegisuchus is a good contender. Sadly, only a braincase, so less visual stuff...
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blaze
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Post by blaze on Jul 5, 2013 1:59:26 GMT 5
Edit: Go to this post for updated size chart including Aegisuchus witmeri. I'm reposting the skulls comparison, I removed from where I had it stored because it had some little mistakes that I have corrected but when I re-uploaded it I did so with a different name, breaking the existing links. Sources for their dimensions: Deinosuchus Farlow et al. 2005. Femoral Dimensions and Body Size of Alligator mississippiensis: Estimating the Size of Extinct Mesoeucrocodylians. Journal of Vertebrate Paleontology, Vol. 25, No. 2 (Jun. 27, 2005), pp. 354-369 Purussaurus Moreno-Bernal. 2007. Size and Palaecology of Giant Miocene South American Crocodiles. Journal of Vertebrate Paleontology, Vol. 27, No. 3, Supplement, pp. 120A. Abstracts of Papers. They were downsized by the use of regression equations based on the American alligator which arguably is closer to Deinosuchus and Purussaurus in both morphology and phylogenetic position than the nile and saltwater crocodiles which were the base of the equations used to get the earlier, bigger estimates. For that same reason I think Sarchosuchus was also in the same size range as them (5 tonnes), rather than the 8 tonnes estimated by Sereno which frankly, implies a scaled up saltie with an svl of 5.7m. (total length of 11.7-12.2m). And Aegisuchus WOW... though I remain exceptical, the next largest crocodiliforms seem to top at 10-11m and ~5 tonnes and this one is supposedly 15-22m and 13-40 tonnes? that's crazy.
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Post by theropod on Jul 5, 2013 19:09:06 GMT 5
It would be interesting to know which scale-base is best for Sarcosuchus, since it isn't close to any of these animals. I'd have no problem with extinct crocodilyforms outsizing true crocodilians. Aegisuchus sounds like a promising contender, but it seems too astronomic to be anything but initial hype.
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blaze
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Post by blaze on Jul 5, 2013 20:49:33 GMT 5
I've been thinking that maybe the gharial is the best we have (so Sereno's lower estimate of 11.1m), do you remember that size chart I made with Sarcosuchus dorsal view from Sereno et al and a scaled up saltie with a 5.7m SVL in side view? while it didn't look that bad in the dorsal view, in the lateral one the skull looked comically small, the whole skull with articulated jaw was no taller than just the skull of the saltie.
Something else that might be of interest, I got the mean rostral proportion (mid rostral width/snout length) of the reconstruction of Sarcosuchus from Sereno et al. (2001), is 0.24, which is higher than the values of the gahrial and false gahrial (0.10 and 0.18 respectively) and comparable to the slender-snouted crocodile (0.25) and the fresh water crocodile (0.24) according to Erickson et al. (2012). I also got that value for the reconstruction of Deinosuchus (which is for an skull around 1m long) and Purussaurus (a 1.2m skull IIRC), they are 0.64 and 0.75 respectively, for comparison, the American alligator has a value of 0.69.
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Deleted
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Post by Deleted on Jul 5, 2013 21:25:17 GMT 5
Aegisuchus sounds like a promising contender, but it seems too astronomit to be anything but initial hype. It may seem like it at the higher estimates, but if you use the maximum skull length estimate along with the minimum total length estimate, it actually looks more believable. |
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Post by theropod on Jul 5, 2013 22:05:32 GMT 5
I've been thinking that maybe the gharial is the best we have (so Sereno's lower estimate of 11.1m), do you remember that size chart I made with Sarcosuchus dorsal view from Sereno et al and a scaled up saltie with a 5.7m SVL in side view? while it didn't look that bad in the dorsal view, in the lateral one the skull looked comically small, the whole skull with articulated jaw was no taller than just the skull of the saltie. Something else that might be of interest, I got the mean rostral proportion (mid rostral width/snout length) of the reconstruction of Sarcosuchus from Sereno et al. (2001), is 0.24, which is higher than the values of the gahrial and false gahrial (0.10 and 0.18 respectively) and comparable to the slender-snouted crocodile (0.25) and the fresh water crocodile (0.24) according to Erickson et al. (2012). I also got that value for the reconstruction of Deinosuchus (which is for an skull around 1m long) and Purussaurus (a 1.2m skull IIRC), they are 0.64 and 0.75 respectively, for comparison, the American alligator has a value of 0.69. Yeah, I had tought the slender-snouted crocodile or fresh water croc were probably closest. sarcosuchus definitely has an odd skull shape. |
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Post by Grey on Jul 7, 2013 6:41:33 GMT 5
blazeDoes your estimate for 5 tonnes for 11 mtres had somewhat a peer reviewed behind it or any other clue ? Aegisuchus sounds absolutely spectacular...
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blaze
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Post by blaze on Jul 7, 2013 7:25:19 GMT 5
11.15m is the estimate of the regression equations of skull-length/total length for the gharial, from Sereno et al. (2001), he used this one and the estimate based on saltwater crocodile (12.15m) to get his mean total length of 11.7m. The 5 tonnes is a guesstimate by comparing the size of its skull to that of the largest specimen of Purussarus which Moreno-Bernal (2007) estimates at 10.3m in length with a mass of 5 tonnes.
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Post by Grey on Jul 7, 2013 10:39:10 GMT 5
If Aegisuchus turns out to be valid in its size estimate, this would make it the largest carnivorous animal that ever stalked at one given time the land.
Imagining a possible 22 metres crocodile-like animal is quite incredible.
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Post by Deleted on Jul 7, 2013 10:58:39 GMT 5
If Aegisuchus turns out to be valid in its size estimate, this would make it the largest carnivorous animal that ever stalked at one given time the land. Imagining a possible 22 metres crocodile-like animal is quite incredible. If it does, that would be amazing, shattering all previous records of crocodylomorph size by a massive margin. But I seriously doubt that that would be the case. Given that it's probably a sprawling animal, I say that the ~15-meter figure is the most likely imo. |
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Post by Grey on Jul 7, 2013 11:01:59 GMT 5
If Aegisuchus turns out to be valid in its size estimate, this would make it the largest carnivorous animal that ever stalked at one given time the land. Imagining a possible 22 metres crocodile-like animal is quite incredible. If it does, that would be amazing, shattering all previous records of crocodylomorph size by a massive margin. But I seriously doubt that that would be the case. Given that it's probably a sprawling animal, I say that the ~15-meter figure is the most likely imo. I agree and in the paper they suggest favoring this figure. Though 15 m+ still represents the same record. |
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blaze
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Post by blaze on Feb 3, 2014 4:11:27 GMT 5
I think even 15m is massively overestimated, the width of the roof of the skull (width between postorbitals?) is only 14.5cm, compare this with 43, 48 and 50cm estimated for the largest skulls of Purussaurus, Deinosuchus and Sarcosuchus respectively, barring a piece of the frontals the whole skull fragment of Aegisuchus described as "partial braincase with skull roof, temporal, and occipital regions" fits in the supratemporal fenestra of the Sarcosuchus skull from my size chart above.
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Post by Infinity Blade on Feb 3, 2014 5:18:29 GMT 5
So are you saying Aegisuchus too might have been in the ballpark of 5 tonnes? I wouldn't be too surprised if that were the case, it seems most of the largest crocodylomorphs were no bigger than your average elephant.
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blaze
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Post by blaze on Feb 3, 2014 12:30:10 GMT 5
No, much smaller, I don't see how that fragment belongs to a 2m+ long skull.  They are to scale, unless of course I failed at scaling them correctly, which is always a possibility, still, Holliday and Gardner (2012) estimate the exoccipital-exoccipital width of the skull in ~23cm, that same measurement in MNN 604 is 51cm and if that measurement is comparable to maximum cranial width when measuring live crocodiles then that measurement in lolong is 22.8cm. I've updated the size chart, it now includes Aegisuchus witmeri, the reconstruction is based on Stomatosuchus which frankly, is more deserving to be there as its skull is about twice as big as that of Aegisuchus if my scaling is correct.  If Aegisuchus has the same snout length ratio as Stomatosuchus (85% of the skull) then a skull length comparable with Gavialis (snout 75% of the skull) will be 60cm, entering that number into Young et al. (2011) equation for total length from dcl in Gavialis gives a result of 3.8m, then we add the rest of Aegisuchus snout and we get a total length of 4.2m. |
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Post by Runic on Feb 3, 2014 15:27:20 GMT 5
I wonder if Purrusaurus was built similar like a Black Caiman, if so it should be the biggest.
"Black caiman are relatively more robust than other crocodilians of comparable length. For example, a 3.9 m (13 ft) adult was found to have a considerably heavier and longer skull than a 4.8 m (16 ft) Nile crocodile (Crocodylus niloticus)"
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