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Post by Grey on Jun 9, 2015 19:04:01 GMT 5
Basically using the available data about meg body mass from Gottfried, I still tend to consider meg to be plausibly a tad heavier at the same length than the modern sperm whale, and Livyatan as well (except if we assume an animal more heavily built than Physeter).
That's why, despite regular investigations, I usually tend to still consider meg as the largest apex predator/macropredator.
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Post by creature386 on Jun 9, 2015 19:50:30 GMT 5
Basically, you're suspecting Livyatan to have reached a larger size than Physeter and Carcharocles as well ? I'm not one of them, but smaller average size do not always imply smaller maximum sizes (the komodo dragon is a good example for that), particularly if both animals aren't closely related.
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Post by theropod on Jun 9, 2015 21:08:58 GMT 5
^Indeed no, and we don’t know the size distribution in Livyatan. But in Physeter, maximum size is far larger than average size, just like in meg. ^^I’m curious to see blaze’s chart for exactly that reason, but note that the Physeter-based Livyatan is presumably at least a bit more robust than Physeter, since it’s rostrum and mandible are (which are both much more slender and contribute a larger part of body length in Physeter). Average masses are likely comparable based on Carcharodon length-mass-regressions.
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Post by Grey on Jun 9, 2015 21:21:18 GMT 5
Yes based on Physeter it would be more massive indeed I forgotten that part.
I plan to ask Bianucci if he has some unofficial body mass estimate for Zygophyseter.
I still tend to rely on Gottfried data for meg even though I admit we can discuss it. I'm still okay with the reconstruction of meg being at least partially bulkier than white sharks.
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Post by theropod on Jun 9, 2015 21:25:18 GMT 5
There is nothing inherently better or worse about the regression in Gottfried et al. 1996 as opposed to the numerous other similar ones in the literature.
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Post by theropod on Jun 12, 2015 6:08:54 GMT 5
So, none of these appear to me to outsize the two conservative figures for Livyatan. Meg seems slightly deeper along the middle in this model (only at length parity tough), though that's visually enhanced by the large vertical fin areas. Also, physeteroid's bodies don’t thin down as rapidly from there, so I guess their bulk is also about the same. Conservatively speaking, this seems to be roughly size parity, perhaps with a slight edge to the larger Livyatan model. What the data don’t support is C. megalodon, as a species, being larger.
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blaze
Paleo-artist
Posts: 766
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Post by blaze on Jun 12, 2015 7:48:34 GMT 5
About the body depth of C. megalodon, the sketch in which I based my sillouette has some notes on it about proportions of certain parts in relation to the fork length, I had not checked before but I did now and the drawing does not have the appropiate proportions, body depth is 12% too great and the distance from the dorsal fin to the caudal fin is about 8% too short.
I'll need to tweak it, which reminds me that I have to reconstruct a jaw, to get more accurate head to body proportions.
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Post by Grey on Jun 12, 2015 9:52:51 GMT 5
I still have doubts regarding the relative thickness at the back of the Zygophyseter model.
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Post by theropod on Jun 12, 2015 14:00:02 GMT 5
It might have to be a little more robust when looking at our friend Brygmophseter, but based on the only information available for Z. varolai this seems fine to me for now. Obviously it would be great to have the latter's description paper though.
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Post by Grey on Jun 12, 2015 16:23:57 GMT 5
I'm not convinced either that Brygmophyseter is particularly robust at the back. Also while the caudal peduncle is thick in lateral view in cetaceans it is finner in dorsal view, while the other situation prevails in sharks. I'll discuss this with fossil odoncetes researchers but I don't think Brygmo is especially robust either.
I dont think the smaller Livy beats the larger meg here.
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Post by theropod on Jun 12, 2015 16:58:13 GMT 5
Me neither, but it doesn’t have to (it’s the largest meg vs the smallest Livyatan), the sperm-whale based Livyatan is almost a metre shorter than the largest meg. I think the larger whale (and that’s the conservative one of the two figures based on Zygophyseter) equals or beats it tough.
The average for female megs seems to be larger than the lower estimate for Livyatan, but does that mean anything? The smaller Livy is definitely on par with, or more formidable than, the other two, which are the ones that actually include both sexes. I consider 14m to be the best figure for reasons explained when I made the estimate (it follows common practice of determining adult/immature status when sex is not known in shark research).
The skeleton you posted of Brygmophyseter is very bulky, with a deep chest compared to its skull, and a very robust skeletal structure. If that specimen was the real thing, then there’s really no question about its robusticity. Anyway, I wasn’t proposing to make the silhouette bulkier, I said I was fine with it.
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Post by Grey on Jun 12, 2015 17:05:27 GMT 5
I can roll with it but I still think the actual body shape of the whale could be tweaked with time. I don't think using one view of the skeleton of Brygmo makes a definitive statement about its robustness. If that thing was really even more robust than an orca, this would be noticed and reported in this particular taxon.
I have the description of Zygo btw.
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Post by theropod on Jun 12, 2015 17:07:38 GMT 5
Could you send it to me?
Yes, the body shapes of both will obviously receive updates with time, but I don’t think this will massively change how their robusticity will compare.
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blaze
Paleo-artist
Posts: 766
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Post by blaze on Jun 12, 2015 18:46:18 GMT 5
Was the skeleton of Brygmophyseter found in articulation? I have the impression that the tail is missing vertebrae.
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Post by Grey on Jun 12, 2015 18:50:14 GMT 5
Once I m back at home I ll send you the paper theropod.
Yes blaze I think the skeleton is missing some vertebra.
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