blaze
Paleo-artist
Posts: 766
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Post by blaze on Jun 6, 2016 8:19:54 GMT 5
theropodYou can use the CT scans from here, you can actually select either the upper or lower jaws and manipulate them.
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Post by theropod on Jun 6, 2016 14:01:10 GMT 5
Thanks, that’s helpful! Is there some way to move the perpendicularly though, without turning it at the same time? I can’t manage to get a closeup of the ventral side of the sharks’s head in the main viewport because it always zooms in on the center of the entire shark.
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blaze
Paleo-artist
Posts: 766
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Post by blaze on Jun 6, 2016 14:17:03 GMT 5
theropodUse focus and lock, it's tricky but it can be done.
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Post by theropod on Jun 6, 2016 14:39:17 GMT 5
Already tried that. Focus seems to be how I got the jaw in the secondary viewport, where I did indeed manage to zoom in on it (but the whole viewport is a bit small). Lock does literally nothing, except that now I somehow have two sharks instead of one. In any case, here it is without the lower jaw of Livyatan, so that both are really comparable: Attachments:
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Post by neogeneseamonster on Jun 6, 2016 16:34:00 GMT 5
Great work again theropod, it looks even better than the previous one. However, I feel that we need to calculate more 'practical' bite size as well. That is, rather than the size of entire inner area of lower jaw(I think it represents the size of oral cavity rather than 'bite size'), the actual size mouth better represents the 'bite size' IMO. Though we do not know exactly how big their mouth were(since there are no soft tissue remains for either animal), we can make rough guesses. For example, when fully opened, great white sharks' mouth end right at(or slightly behind)the point in which their tooth row end(as seen in the picture below). (I've also found that two species of makos and salmon sharks show the same features as well). similarly, I realized that almost every whale's mouth does not extend beyond their eyes(in fact, most whales' mouth end in front of their eyes). I've checked sperm whales, killer whales, false killer whales, all species of oceanic dolphins, beaked whales,river dolphins, and belugas so far and the only exception was ganges river dolphins(which does not have lenses). Examples(killer whale): www.google.co.kr/search?q=salmon+shark+mouth+open&hl=ko&biw=1366&bih=651&site=webhp&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwj6rr76nJPNAhXlN6YKHXo4BfIQsAQIHw#hl=ko&tbm=isch&q=killer+whale+mouth(sperm whale): www.gettyimages.com/detail/photo/large-adult-male-sperm-whale-with-open-high-res-stock-photography/114997000
Thus, maybe we can predict megalodon and Livyatan's mouth range by using this as a reference.
PS. So far, I wasn't able to find any scientific documents to support my observations so I'm curious about how others consider this.
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Post by Infinity Blade on Jun 7, 2016 2:39:07 GMT 5
To my understanding, the green-shaded areas represent the size of the bite relevant to this fight (no rhyme intended). But I can see that the green area extends to well beyond Livyatan's toothrow. Wouldn't the whale's "bite size" actually terminate once the toothrow ends?
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Post by theropod on Jun 7, 2016 14:13:36 GMT 5
Actually that’s not what they are meant to represent. The green-shaded areas are the areas within the animals’ jaw perimeters, everything within the line drawn through the toothrow and to the jaw joints. This is a measure of the size of their oral cavities, and hence to some extend of how much they could engulf in one bite, but more so it is a measure of the overall size and power of their jaws (because both include the in-levers and insertions of the jaw musculature and the entire apparatus that is agape when the jaws are opened). However, the way they functioned was obviously very different. Livyatan is a sort of T.rex-analogue, with a solid bony palate, massive peglike dentition and lower teeth positioned just medial to the upper ones to generate high shear stresses when clamping down. It’s also arguably a lot more adapted to gripping and manipulating whatever it bit as opposed to a quick bite and release. On the subject of gape angle, I’ve found a source for Physeter macrocephalus ( link→) and one giving a minimum value ( >60° link→) for Kogia, but it would be very important to compare these values to Orcinus and Pseudorca, so if anyone has proper information on either of those two, it would be helpful.
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Post by Grey on Jun 12, 2016 7:55:56 GMT 5
Good work indeed.
I have some doubts about the exact jaw perimeter in Livyatan if it would extend that behind the tooth row.
Is it legit to use the alternative data from the megalodon CMM mount ?
If so, the measurements would be :
trl : 3.45 m
jp : 4.56 m
jaw area : 2.20 m2
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Post by Grey on Jun 17, 2016 19:24:38 GMT 5
theropod blazeAre you sure the Livyatan oral cavity would extend like this ? Using in Lambert et al. the part were the lower jaw joints with the upper jaw, I rather got something in that region (here compared with the chondocranium of the Gottfried et al. megatooth shark model scaled at 17 m long).
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blaze
Paleo-artist
Posts: 766
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Post by blaze on Jun 17, 2016 21:48:36 GMT 5
GreyIf "tf" in the diagram means what I think it means (temporal fenestra) then no, the oral cavity will only be as wide as the distance between posteriormost teeth.
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Post by Grey on Jun 17, 2016 22:13:14 GMT 5
I wasn't talking about the width itself but rather the length of the cavity. It necessarily extends up to the temporal fenestra?
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blaze
Paleo-artist
Posts: 766
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Post by blaze on Jun 18, 2016 7:45:50 GMT 5
Oh, maybe, I'm not really sure, sorry.
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Post by Grey on Jun 19, 2016 5:03:24 GMT 5
There is a short discussion about Meg vs Livyatan in a recent Nat Geo doc, Sea Monsters : the definitive guide. They conclude Livyatan, because of its social skills, would win, as an orca analogy. However they seem to imply meg would have the edge one on one. yourvideohost.com/xix0kti9w5wr starts at 15.40
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Post by theropod on Jun 19, 2016 16:09:42 GMT 5
The jaw perimeter is the measurement around the jaws, up to the joint. That’s what I (and by the seem of it, blaze too) measured. The mandibular condyle is even marked in the paper (Mc), so there isn’t a lot of ambiguity there. As I already wrote, that’s related to the size of the oral cavity, which is not a direct proxy for how much of it is exposed by the oral margin (which as already mentioned indeed shouldn’t extend much behind the orbit, which is roughly consistent with what you showed). That part you marked would go inside the temporal foramen when the jaw was fully articulated (it obviously is not in the picture, because doing so would obscure the lower jaw).
Regarding how legit it is to increase the size of C. megalodon’s jaws further, the largest teeth in the version I posted are already pushing 16cm in root width and several are around 15cm wide, which is still the current record among reasonably reliable specimens, if I’m not totally mistaken. So a larger jaw perimeter than this only works with proportionately reduced dentition size.
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Post by Grey on Jun 19, 2016 17:36:42 GMT 5
Yes, but I have the impression that jp doesn't have the same implication in both, in the case of the shark it seems to directly reflect the area of organic substances taken by the bite. In the whale this extends, to my eyes, well beyond that, the green shaded part of the mandible extends in the posterior part of the joint, which doesn't seem to be practical and reflecting the area of bite size. Unless I miss something?
Yes, the CMM meg jaws scaled up at 18m would imply proportionally smaller, more spaced teeth. Or maybe some negative allometry of the head? Note though the teeth in the jaws are GWS, using the same anterior tooth width for meg and GWS implies a quite longer dentition in the first.
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