Livyatan

[GuateGojira]

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. Reply