Size comparisons

[LonePredator]

(05-09-2022, 09:45 PM)GuateGojira Wrote:

(05-08-2022, 11:44 PM)LonePredator Wrote: About the Wildlife Institute of India data. Lots of things are wrong and unreliable about it. Let me explain...

It’s possible that they put this data by mistake because it says “an adult may reach 4.5m (18ft) in length” but the conversion is wrong. 4.5 metres is 14.75 feet but it says 18 feet which is wrong. 18 feet is 550cm but it’s possible that 18 feet is referring to the 563cm length by Whitaker which is 18ft 5.5inches but they may have rounded it off to just 18feet. I strongly believe this is the case because they even cite a source belonging to Whitaker just in the next paragraph.

*This image is copyright of its original author

*This image is copyright of its original author

And again that 450kg weight is unreliable because no such confirmed weight of 450kg exists for a Mugger and as expected, they did not provide any source for the 450kg weight either.

Now, as the 5.63m length by Whitaker is reliable and is based on 2 specimens, then the maximum possible weight for a Mugger crocodile of 5.63m would definitely be A LOT more than 450kg.

A 5.63m Mugger should be about 1,000kg or more based on the 195kg weight and the 111kg esimate by Brander but even if we assume same weight/length relation as other crocodile species, it would still be around 2 times more than 450kg so the maximum weight for a Mugger should be around 1000kg or more. I would personally say somewhere between 1050-1150kg for that 5.63m Mugger but I can’t say it with enough conviction as we have very less data for Muggers.

In fact, every normally available information about crocodilians seems VERY wrong to me. The standard of size of crocodilians is normally considered by their length rather than weight except for the obvious Gharial and this is so wrong and this is likely also due to the fact that there is lot of data about length of crocodilian species but barely any weight data so people just compare them based on length.

People say Nile Crocodiles are the largest after Saltwater Crocs but there is nothing concrete to support this claim because with the data I have seen of 50 years ago, the average weight of Nile Crocodiles is only around 200kg @ 3.66m in Lake Turana (Graham, 1968), 3.65m from Kruger so the weight should be same in Kruger too (Guggisberg, 1972) I only have access to the first one so I’ll attach the link below. (See page no. 76)

http://ufdcimages.uflib.ufl.edu/aa/00/00/75/90/00001/lakerudolfcrocodilesalistairgraham.pdf

As Whitaker mentions that the average Muggers are 300-350cm then let’s assume 325cm (3.25m), then 325cm Muggers can definitely be as heavy or even heavier than average Nile Crocodiles based on the 195kg weight @ 300cm (which was not even as bulky as normal full sized Muggers) and 111kg estimate @ 273cm by Brander but again this is so few data to make a concrete statement.

In terms of weight, that 5.63 metre Mugger could even be heavier than the Lolong Saltwater Crocodile of 1075kg but as long as the 5.63m croc was not in a starving and emaciated state, there’s NO way it was any less than 850kg.

I have seen data which STRONGLY suggests (but not enough to prove) that Muggers could likely be the third heaviest or probably even second heaviest living crocodilians in terms of average weight and that 5.63m specimen could have even been heavier than Lolong but at least 800-900kg minimum.

As you said the largest reliable weight for the American Crocodile was just less than 600kg, then the 5.63 metre Mugger was definitely much more heavier than that American Crocodile specimen as well. The minimum possible weight for that 5.63m Mugger is 850kg unless it was in a starving state but a ton seems more likely so the maximum weight for Muggers should be stated as at least 850kg.

Been honest, very few crocodilians had been weighed, I mean "actually" weighed, and most of the figures, even in official books, are estimations.

For saltwater crocs, I think that we have only a couple of real weights, most from captivity, the same for other species. Resently I checked a document about a black caiman (one of the biggest crocodilian species) and mentioned a large specimen of 4.2 m that weighed only about 350 kg and looks normal. However, again, we see the type of error that you mentioned, as the animal is described as 13 ft long (3.96 m) but latter it says that is 4.2 m, so, which is the correct one? This is the paper: https://www.wemjournal.org/article/S1080...1/fulltext

So this confusion difficult to take a good appreciation of size and weight, specially in animals that has been studied very poorly regarding its body mass.


With such a few information, we can't be sure which is the heaviest specimen on average, or the heaviest in relation with its length. We need real data and for the moment we don't have it.

We must remember that while Romulus Whitaker is one of the most reliable sources on crocs, he did not measured those two specimens of 5.63 m, but he quotes Deraniyagala (1939), so it will be interesting to see the original source and see if Deraniyagala actually measured or saw the measurements of the animals, or if he was just quoting a hunting record, like the unreliable figure of 6.8 m for an Orinoco croc, that is often quoted by experts, but when we check the original source, it don't even say how they measured the animal.

Whitaker says that the average male is between 3 - 3.5 m and at 1890 the biggest specimen in the Brithish Museum was of 366 cm, althouth the author accepted that bigger do exist (Boulenger, 1890). Certainly we need more information about this croc species.

Actually, we have much more weights of saltwater crocodiles but you’re right that most weights are of captive specimens but it’s the same case for most other crocodilian weights as well.

Nile and Saltwater crocodiles weights are much more available than any other species. But normally weights don’t seem to have much variation among captive or wild specimens.

For now, I found this one with weights and lengths of 44 Saltwater specimens but there there is more data too :

*This image is copyright of its original author

Link

Now, if you calculate the weight for a 5.63m Mugger based on these saltwater weights, it would still be 800-900kg (assuming that Muggers are the same weight as Saltwater Crocs at same length).

But techically it should be even heavier because Muggers are the most ‘alligator-like’ and hefty in terms of morphology, they have the broadest snouts among all living crocodiles and likely the third broadest among all crocodilians only behind Chinese Alligator and Broad-Snouted Caiman which suggests that they are the heaviest crocodiles at equal lengths and the little data we have about their weights also reflects this characteristic of Muggers.

As for the lengths, if I quote Whitaker word by word, this is what he said “The maximum RELIABLY recorded length for the Mugger is 5.63m based on 2 specimens”. So he does makes it clear that the 5.63m length for the Mugger is reliable and there doesn’t seem to be doubt about it’s reliability. Also Deraniyagala (1939) stated this length in the Ceylon Journal of Science, the Tetrapod Reptiles of Ceylon Vol 1 so I don’t think a journal as such would mention a hunting record.


Now, for the Black Caiman, from what I roughly saw, Black Caimans are generally around the same weight as most Crocodiles at equal lengths so if you ask me to pick one of those lengths then I would say 4.2 metre seems more reliable to me and a 4.2 metre Black Caiman weighing 350kg seems normal and makes more sense.

And interestingly, as far as I remember, the longest Black Caiman actually recorded is only about 14 feet but they still accept that Black Caimans could exceed 16feet 5inch and on basis of that, they make the claim that Black Caimans are very large even though there is no concrete proof of a 16feet 5inch Black Caiman specimen.

Same is the case for American Crocodiles and Orinoco Crocodiles, no known reliable lengths over 5.5 metres but there are still claims about Orinoco, Black Caiman and American Alligator being the 3rd, 4th and 5th largest crocodilians. But these claims have been made on the basis of unreliable information without any proof to back these claims.

So in case of Muggers, 5.63m is much more reliable than 5 metre Black Caimans or 6.8 metre Orinoco Crocodiles (which is literally from 222 years ago). The highest known reliable lengths of Muggers is higher than that of Orinoco Crocodiles, Black Caimans or American Crocodiles and with that length, the weight of that Mugger would be much higher as well.

With the reliable data that we do have available, it shows that Muggers have attained larger sizes than all other crocodilians except Nile and Saltwater Crocodiles and this is despite the fact that data about Muggers is so scarce. Reply