Size comparisons

[GuateGojira]

(11-14-2022, 10:54 PM)AndresVida Wrote: of course, I got it from here

https://twitter.com/fishboy86164577/stat...3694159872

So, the estimation was done by an artist, not by the Paleontologists. Honestly that concerns me, as I have the original paper of Bianucci & Landini (2006) and they do not provide exact measurements from the bones, just about the skull and a few random measurements of some vertebrae. Unless that this artist has a document that we don't have, I will take that representation like his interpretation, and like a grain of salt. 

This is the only picture that I found of the real fossil (entire body) of Zygophyseter, housed in the Museo dell’Ambiente dell’Università del Salento (MAUS):

*This image is copyright of its original author

Here is a draw of how it was found:

*This image is copyright of its original author

And here a reconstruction based in that fossil in the same museum:

*This image is copyright of its original author

*This image is copyright of its original author

If you check its size, definitelly is over 6 meters long and it doesn't look like the "funko" image created by the artist. I know that many people is happy and accepted this "new" reconstruction without hesitate, but honestly I will like more details before fully accept it. PLEASE don't missunderstand me, is not that I am saying that the image of "Fishboy" is false or incorrect, is just that with no backup data, it is really hard to me to accept that reconstruction, but if he provide the source of his measurements that will be great.

Now, I really hope that the measurements that he used are those taken in the real fossils and not estimations based in pictures using the scale bars in the paper, because that is not a correct form to estimate the size, after all the pictures can (and often do) provide incorrect dimentions. That is why all reconstruction must use the measurements taken by the scientists and published. Using only pictures is not correct, and believe me, I know it from first hand.

Let me use the example of another raptor sperm whale Brygmophyseter. Most of documents and even Wikipedia quote its size as between 6-7 meters and compare it with Zygophyseter, however there are some contradictions that honestly confuse me, let me start.....

In this image it says that the skull is of "about 140 cm":

*This image is copyright of its original author

This of course do not provide any detail as if this is the "real" length of the fossil (incomplete) or if is the estimated size when complete. Also, is not an official document. Now let's check a published and per-review document:

*This image is copyright of its original author

This is from Bianucci & Landini (2006) and Naganocetus is just a synonimus of Brygmophyseter. Here it says that its skull was "at least 1.5 m", so this suggest that this is the estimated length of the skull "reconstructed".

Kimura et al. (2006) provided a series of measurements from the bones, but sadly did not do the same with the skull, so here is the table where all the known vertebrae are reported:

*This image is copyright of its original author

Please check that no cervical vertebrae (neck) is known:

*This image is copyright of its original author

So, IF I am reading the measurements correctly, the blue square has the vertebrae in line that we can use to reconstruct the body length of the animal. About the neck, as we don't know its size we can check this image from a modern female orca of 6.7 m long, please take in count that the neck is small and the space presented here is just because the neck is still not joined to the column:

*This image is copyright of its original author

I know that this is a completelly different Genus, but we can estimate a "neck" of 15 cm for Brygmophyseter.

So, with a vertebral length of 3209 mm and a neck of 150 mm, there is an estimated body length of 3359 mm, and adding a 10% for intervertebral discs, the body length between neck to tail could be about 3694.9 mm, or about 370 cm in round numbers (remember that many bones are estimated and less than the true value and also that the intervertebral disc percentage is just a conservative estimation.

Now, if we use the c.140 cm from the webpage, the total length for Brygmophyseter in the skeleton will be about 5094.9, or about 510 cm, but if we use the figure from the published paper of "at least 150 cm", the total length will be of 5194.9, or 520 cm. This is far from the 6-7 meters ofter quoted and is just a raw estimation based in the available data. Now if we take in count muscles, fat, other conective tissues and the cartilaginous part of the tail (the flipper), we can estimate a total length in life of about 5.6-5.7 m depending of how large we estimate the flipper (50 cm in this case). So, in few words, the best raw estimation of size "reconstructed" will be between 5.5 - 6 meters. My problem here is which is the correct estimated size for the skull, 140 cm or 150 cm? Personally, I go for the paper on this, but if some can present more information, or correct the measurements used, be my guess.

Now, why I have done all this process? Well, to show that take measurements from images is not the correct one, now we going to check the images in the internet:

1 - Jaime Bran:
This is a reconstruction from Jaime Bran, a reliable artist and a good source:

*This image is copyright of its original author

In the DevianArt page, he says that the size is of 5.5 m, which match with the information that I provided previously. HOWEVER, when I started to measured the draw I found something interesting. I measure it three times using pixels and the result is 6 meters from tip of reconstructed skull to the last caudal vertebrae along the centra, and a skull lenght of 140 cm, milimeters more - milimeters less, not an exact size as it depends of who measure it, after all is just a draw and not the real skeleton. So, this bring the problem again about the size of the skull, as based in this, and using the scale bar, the size that he used was 140 cm, but it gived the same size that I gut using the skull of 150 cm. Definitelly I will love to talk with him just to clarify some points. Here we can see an example of the issues to use a draw to estimate a size. Now another example.

2 - Kimura et al. 2006:
We all know the picture at the end of the document of Kimura and team, here it is:

*This image is copyright of its original author

This is the image used for many reconstructions but sadly the authors do not provided any scale for reference. 

If I use the raw skull (broken) the total length of the animal range between 632.9 cm (skull of 140 cm) and 678.1 cm (skull of 150 cm)! Certainly an unlkely size based in the real measurements and the fact that the skull is broken, but this is just to give you an idea.

Now, if we estimate that the skull is a bit longer, just slightly longer than the lower mandible, the total length of the animal range between 603.4 cm (skull of 140 cm) and 646.5 cm (skull of 150 cm). The lower figure is more realistic, but again, we are just guessing from the air, if you know what I mean. Also, the skull is shorter than we think and this image is misleading in this part, check the third image....

3 - Picture of Shiga Fossil Museum:
And here is a recent picture of 2018 that I found and check the skull:

*This image is copyright of its original author

Now compare it with the picture from Kimura et al. (2006) and we can see that the skull is shorter than we think and that the mandible is bigger. This demostrate that using pictures is NOT a good form to estimate sizes as the pictures are misleading in many cases. But just for FUN, let's see what we can get with this image:

*This image is copyright of its original author

I completed the last part with the image of Kimura and this is what I got. Now we can see that a piece of metal completed the estimate length for the skull and here is my result:

With the skull of 140 cm, a total length of 560 along the centra.
With the skull of 150 cm, a total length of 600 along the centra.

Again, all depend of the skull size and also the angle of the picture. This confirm that using pictures to estimate a size is not a good indicator and we must use only the published measurements. Check that while the calculated sizes range between 5.5 to 6 meters, it change depending of the angle of the picture, the measurements and the source quoted.

That is why I will like to know which sources they used for they calculations, just the make sure of the results. And take this in count, if all this confusion can happen with specimens where we know more or less the body size and proportions, imagin how problematic is to build an animal that we only know the skull!!! So, the "new" size of the Livyatan, for me, is not the final stone in the grave, not at all. Reply