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Livyatan
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  *This image is copyright of its original author  *This image is copyright of its original author  *This image is copyright of its original author Its total length has been estimated to be about 13,5-17,5 m similar to moderns sperm whale (Physeter macrocephalus), making it one of the largest predators to have ever existed. The tallest tooth measured 36,2 cm it is the largest tooth of any known animal, excluding tusks. It is distinguished from the other raptorial sperm whales by the basin on the skull, and how it spans the entire length of the snout. The holotype skull of Livyatan was about 3 m long, like other raptorial sperm whales, Livyatan has a wide gap in between the temporal fossae on the sides of the skull and zygomatic processes on the front of the skull, indicating a large spece for holdind strong temporal muscles, which are the most powerful muscles between the skull and the jaw. Unlike the modern sperm whale, Livyatan had functional teeth in both jaws. The wearing on the teeth indicated that the teeth sheared past each other while biting down, meaning it could bite off large portions of flesh from its prey. also the lower jaw contained 22 teeth and upper jaw contained 18 teeth. credtit for information to Wikipedia, pictures and images credit to @a_fools_experiment
Comparing Lyviatan and Megalodon
By Harry the fox  *This image is copyright of its original author
Credit to @cofcnaturalhistory
 *This image is copyright of its original author  *This image is copyright of its original author  *This image is copyright of its original author  *This image is copyright of its original author  *This image is copyright of its original author  *This image is copyright of its original author
On the size of Livyatan:
It is not surprise at this moment that a new "unofficial" estimation of size for Livyatan melvillei has been released by the artist Tosha Hollman, known as "FishBoy". He used the proportions of Brygmophyseter to estimate the size of Livyatan and his conclution is that the last one probably measured about 12.5 meters long, here is the link of his post: https://twitter.com/fishboy86164577/stat...3694159872 Here is the image:  *This image is copyright of its original author From some time ago I was playing with the idea to check the size of this big cetacean and I made several draws, but to be honest all the estimation of 16 meters look weird unless that I used a modern orca as a model (and looks cool!), and the estimation of 17.5 meters looks to skinny/long or with a head to small for a "sperm whale", altough we need to take in count that our modern "sperm whales" (the big one and the two small ones) are very derived from the "original" form, so our mindset allready have this bias toward the modern morphology. Now, I found this image some time ago and I thought it was correct:  *This image is copyright of its original author However in my last post (https://wildfact.com/forum/topic-size-co...s?page=110 - post 1647) I found that while the picture in Kimura et al. (2006) shows the complete known skeleton, the skull itself is not correctly presented, this is based in this new picture from 2018 where we can see a much better view of the original skull, check it:  *This image is copyright of its original author This new picture shows that the skull and mandible is longer than previously represented and appart from the fact that I could not found an especific measurement for the skull, which is described "about 140 cm" or "at least 150 cm" (conflictive descriptions!), the estimation of size for Livyatan will change significantly with the new proportions. So, I made my own comparative image just "for fun", as remember that any comparative image that use pictures and estimations instead of the measurements directly taken from the bones is not reliable, just suggestive at best. This is my result:  *This image is copyright of its original author Description: In the center we can see the original comparative image, no change was done to it. In the upper part we can see the new skeletal reconstruction from the picture of 2018 and hopping that the picture is not distorting anything in a significant manner, we can make a good estimation of the proportion of the skull in relation with the body. Then I scalated the skull (with its reconstruction line) of Livyatan to the same proportion as Brygmophyseter and we can see how it will looks. By the way, I know that the skull is placed too high in relation with the neck, but I made it in that form because I wanted to estimate its total length, just for that. Now, using this new "reconstructed" body and with the new proportions we need to move to the lower part, there I escalate it to match the image with the skull in upper view and addapted the silouete to the new body length (I made it more stockier int he tail area) and the result was an skeleton length of 11.8 meters, and using the previous tail, I got an estimated 70 cm of tail and the result was 12.5 m of total length, the same as Tosha. Now, let's take in count that the tail is totally arbitrary and may be an underestimation, but for its form, I think it looks ok, but with a little more of fat or muscles, the estimated length the skeleton (skull + body) could be about 12 meters, and with tail of 13 meters, which will be totally fine with the fact that with an extinct animal that is known only from ONE specimen and is only a SINGLE skull, there are NO ABSOLUTE OR "OFFICIAL" SIZES, this means that an estimation between 12.5 - 13 meters including tail is perfectly fine, using the proportions of Brygmophyseter. I mention this last because many people in Twitter just quote the "new" size as a "dogma of faith", when actually is just an estimation that can be very wrong and only when we could found more specimens we can actually sure of the real proportions of this animal. At the end, I added the reconstruction of the artist Carl Buell, but I modified it a little: a lshorter tail (just a bit), eye more at the bottom, stockier body and bigger mandible. Here is the original image:  *This image is copyright of its original author I also added the reconstruction of the skull and possible body of Livyatan made by Tosha Hollman and finally, I added the beautifill image of the male orca from Uko Gorter for reference. So, it seesm that Tosha and I coincided that the reconstruction Livyatan based in Brygmophyseter proportions we got a total length between 12.5 - 13 meters, BUT I am still not convinced about his reconstruction of Zygophyseter, specially when all the data that I saw at this moment suggest a length of no less than 6 meters, like I said before I will like to see his reference for the calculation. Now, there is a problem with all this and we can't ignore it. Reconstruction Livyatan es very problematic, because the phylogenetic three do not place it together with Brygmophyseter and Zygophyseter in the papers from 2015 to 2018 and a new paper place it in the group of Kogia! Trying to reconstruct this animal using "close" relatives is like if we have only ONE skull of a tiger, a random one, and we are trying to reconstruct its body and proportions using the closest known relatives, which in this comparison case will the puma (Brygmo and Zygo) and Smilodon (modern sperm whale). Why I say this? Because the puma and Smilodon are in the same family as the tiger but are grouped in different genus, so its proportions are different and the modern sperm whale (Physeter macrocephalus) will be like an Smilodon becuase is very derived and specialized and its morphology do not match completelly with the older forms, just like the skull of a Smilodon is way different than that of a tiger or a puma. So, this is our problem, we have an unknown animal and the best we can do is to use what we have to reconstruct it, even incorrectly. Other thing, we don't know the sex of the animal (male or female), or its estimated age, or if this was an average specimen, or a big/small one, what age it had, and a long etc..... So, the correct form to quote the size for this animal it to be clear that we only have one specimen and than that specimen had an estimated size of X meters and a calculate mass of X tonnes, but just that, we can't assure that the calculated size is the correct or "official" one, that will be irresponsible, just like many people is writing in Twitter now. We don't know if bigger/smaller specimens existed so absolutes are not the correct form to make science. For the moment this is what I have, and I hope that the last paragraph can make you reflect about the present issue. We can only hope that maybe, in the future, we can found more specimens to complete the gaps. Greetings to all.
Now, continuing with the problem of the skull of Brygmophyseter and its proportion with the body, check these pictures of 2015 from "Kumiko", and from 2017 by "Hetaka":
 *This image is copyright of its original author  *This image is copyright of its original author  *This image is copyright of its original author Is the skull shrinking or enlarging? Is this the efect of the camera and/or distortions of the pictures? Because here the skull is not that short in comparison with the mandible, in fact is closer to the image of Kimura et al. (2006) and not as close as the picture of "Felice" of 2018. This is the problem of using pictures for reference.  At the end, which is the correct proportion and size of the skull?
Comparative image:
Just to show the approximate size of Livyatan, I found this comparative image were the author tried to show the three diferent estimations of size reported by Lambert et al. (2010), he kept the same skull and head size and just increased the body lenght and massiveness, here is the image:  *This image is copyright of its original author There we can see how the body proportions change based in the estimation. From my point of view the lower estimation looks ok taking in count that this is an "sperm whale" (bias based in the current species?). The lenght of 16.2 m works only if Livyatan present a morphology close to the moder orcas, where they have skulls or less than 130 cm but bodies of up to 9 meters. The largest one of 17.5 cm, personally looks odd, but until we found a more or less full specimen, it is just a posibility that is based in another posibility (the size of Zygophyseter is still not clearly defined). Now, following this line, I made a comparative image now, using the "conservative" body size estimated (the lower one) from Zygophyseter (the one in the paper of Bianucci & Landini, 2006) and the one based in the new proportions estimated from the skeleton of Brygmophyseter (no measurements from the holotype are involved, just a side-to-side estimation). Finally I included the biggest sperm whale actually measured and reported by scientists and also the biggest orca actually confirmed. Here is the image:  *This image is copyright of its original author I kept the size of the head in the same form as the first image, but I had to increase the bulkiness of the animal for obvious reasons. On the body mass, the heaviest sperm whale is a male of 57.1 tonnes (total length of 18.1 m) weighed in pieces, but the heaviest male weighed complete was a male that weighed 53 tonnes (18 m), so for the largest males of over 20 m reported in litterature a maximum of 60 tonnes is not out of question. For the orca the heaviest male actually weighed was of 6.6 tonnes (7.65 m) as far I remember, but the biggest specimens of up to 9 m had been estimated up to 10 tonnes, and based in the massiveness of this animal that weight is completelly plausible. Now, on the body mass of Livyatan, there is no document where they actually worked on it. Villafaña & Rivadeneira (2014) did not calculated any body mass or made any formula, they just estimated a weight of 57 tonnes based in a length of 1750 cm, so is just a pure guess. As we don't know the proportions of this animal, is simply impossible to estimate its body mass at this moment, BUT if we use the sperm whales as a modern surrogate, we can make a partial estimation, although with a good margin of error because of differences in the morphology of both species. I got a sample of 47 males with total length and body mass and I found that there is a regional difference, with males from south been heavier on average than those from north: Overall: 35 tonnes - n=47 - range: 16.1 - 57.1. North: 32.5 tonnes - n=28 - range: 16.1 - 57.1. South: 38.1 tonnnes - n=18 - range: 26.3 - 51.7. One male of 49.3 tonnes (15.4 m) was discarded in the regional differences as the location was not provided, but including it in any of the samples creates no significant difference. Now, I created three ecuations usefull to estimate the body mass of male sperm whales: Overall r2=0.7168, North r2=0.8118, South r2=0.8173) and if we applied them to this specimen of Livyatan, here are the results: For a length of 16.2 m Overall: 40.7 tonnes North: 38.0 tonnes South: 45.4 tonnes For a length of 12.5 m Overall: 21.3 tonnes North: 19.2 tonnes South: 21.6 tonnes So, based on this, the body mass of Livyatan melvillei, using the modern male sperm whale (Physeter macrocephalus), could be between 19 - 22 tonnes (total length of 12.5 m) or 38 - 45 tonnes (total length of 16.2 m). However based in the bulkiness of the specimen compared with the sperm whales, is possible that the body mass could be higher than this calculations. |
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