blaze
Paleo-artist 
Posts: 766
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Post by blaze on Nov 13, 2013 21:21:56 GMT 5
Mahajangasuchus is the name bearer of the family and judging by the only skeletal there is it has "normal" crocodilian proportions, even if the relationship is not close, if they had a similar niche they probably have similarities, Phytosaurs had convergent body proportions with modern alligators and they aren't even archosaurs.
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Post by Godzillasaurus on Nov 13, 2013 21:33:48 GMT 5
Is there a mahajangasuchid complete enough for scaling? I believe that, as of now, there are only two mahajangasuchids to work with: mahajangasuchus and kaprosuchus. I am not sure if we have any other fossil evidence of the former aside from its skull, however. |
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Post by Godzillasaurus on Nov 13, 2013 21:43:06 GMT 5
Mahajangasuchus is the name bearer of the family and judging by the only skeletal there is it has "normal" crocodilian proportions, even if the relationship is not close, if they had a similar niche they probably have similarities, Phytosaurs had convergent body proportions with modern alligators and they aren't even archosaurs. That is because it, unlike kaprosuchus, was probably more of an aquatic-based animal that probably had a diet more exclusive to fish and other small animals. Mahajangasuchus probably filled a similar niche to the American alligator, having a diet mainly comprised of fish, shellfish, and testudines (the order that turtles, tortoises, and terrapins belong to), but taking small to medium-sized animals on occasion. This is evident with its (somewhat) similar skull and tooth morphology. Also, the idea of phytosaurs being placed outside of archosauria is all a matter of perception. Different paleontologists have different views on the subject, but IMO, they have so much in common with modern crocodilians that I feel more evidence needs to be presented to properly classify then outside of archosauria. |
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Post by theropod on Nov 13, 2013 21:50:34 GMT 5
Crocodilian skulls can look surprisingly different in terms of robustness depending on the angle. Laterally, they often look quite thin, when viewed dorsally they are immensely thick. Larger and older specimens also seem to have get increasingly robust skulls. Kaprosuchus skull is a little deeper and narrower, this might be consistent with a more terrestrial lifestyle (Seriously, there's very little difference in the arrangement of the eyes, and the overall robusticity is comparable). But speculating on what influences this likely had on its proportions is quite pointless without at least a reference, it is quite unlikely it would exceed the 3-4m range either way. Deeper, perhaps. But narrower? Only in comparison to really large crocodiles (I am talking HUGE crocodiles, as in 17+ feet), as its snout does not taper into a point and remains its overall width throughout, indicating that it preyed on larger terrestrial animals and had a diet less exclusive to fish. Of course, as you already stated, old male crocs can have insanely thick and wide skulls, but this specimen was still probably not fully grown. Again, we only have a skull, so its body to head proportions are unknown i][/i] quote][/quote]Wait, you yourself showed the pictures in your opening post, noting Kaprosuchus' skull was narrower. What do you mean by "was still probably not fully grown"? Not fully grown as in "a small, subadult specimen" or as in "normal adult that has not totally ceased to grow yet"? I can't see any reason to assume the former, and in the latter case there's no reason to assume its anything but a normal representative of its species.  its relatives only bring us this^ far, but I think its quite apparent they are not RADICALLY different from extant crocs in their propportions (the kaprosuchus in that scale actually seems to be scaled to big, since it's scaled to mandible lenght which includes a fairly elongate postarticular process), at least not enough for Kaprosuchus to reach the 5-6m mark (of course, not specking about how large larger specimens may or may not have been, but talking about the known specimen). |
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Post by theropod on Nov 13, 2013 21:55:11 GMT 5
Just a second, have I missed some major overhauling study on archosaurian phylogeny? I tought phytosaurs were archosaurs, relatively basal crurotarsans to be precise. Also, don't they have pretty oversized skulls? like this:  |
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Post by creature386 on Nov 13, 2013 22:24:07 GMT 5
I can't see any reason to assume the former, and in the latter case there's no reason to assume its anything but a normal representative of its species. Actually, there is. Given that crocodiles are R strategists, it's hard to find an adult (that's why saltwater crocodiles above 3 m are very rare). |
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blaze
Paleo-artist
Posts: 766
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Post by blaze on Nov 13, 2013 22:32:37 GMT 5
I didn't say head body ratio, but excluding the skulls (which had greately elongated snouts in phytosaurs as we all know), femur based regression equations derived from alligators predicted SVL of phytosaurs fairly accurately (Hulburt et al. 2003), and yes, Nesbitt (2011)
A summary from Stocker & Butler 2013 "Phytosauria"
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Post by theropod on Nov 14, 2013 0:23:07 GMT 5
Creature386: aren't those already counted as adults?
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Post by creature386 on Nov 14, 2013 0:47:55 GMT 5
They are counted as adults, but some say they don't represent the species quite well, because they are still able to grow a lot (3 and 4 or 5 m is quite a difference).
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Post by Godzillasaurus on Nov 14, 2013 5:49:45 GMT 5
I was talking about subadult crocodiles, not alligators. Crocodiles have much narrower skulls generally that taper off into a point.
I was talking about it not quite being the full size potential for its species. A simple analogy would be to use the saltwater crocodile; big, old males can grow upwards to 23 feet long and at least 2,200 pounds in weight. But the average for male saltwater crocodiles is closer to 15 feet or so.
Of course, but there were still big differences present.
But I must acknowledge that that reconstruction does look inaccurate as it assumes that kaprosuchus had a nearly identical morphology to that of modern crocodiles (I'm talking about it being a terrestrial animal, which there IS evidence for).
Meh, I like to think of them as basal pseudosuchians (crocodile-line archosaurs). But remember, other paleontologists have different viewpoints.
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blaze
Paleo-artist
Posts: 766
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Post by blaze on Nov 14, 2013 14:57:10 GMT 5
No one has refuted Nesbitt (2011) and finding out that none of the characters used to support that hyphotesis were actually usefull for that purpose is a pretty big deal, other paleontologist would have to find new ones, we are beyond classificating taxa by "feels".
Edited
Remember the photo of that alligator I posted earlier? who paid attention to its narial region, any similarity with Kaprosuchus you can see?
I doesn't matter, if the thread was about its proportions, they're pretty much settled, what more is left to be said?
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Post by theropod on Nov 14, 2013 16:56:03 GMT 5
Nowhere did I suggest this single individual represented "the full size potential of its species".
I still don´t get your point regarding its proportions.
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Post by Godzillasaurus on Nov 15, 2013 1:59:16 GMT 5
Nowhere did I suggest this single individual represented "the full size potential of its species". I still don´t get your point regarding its proportions. Are you talking to me or blaze? |
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Post by creature386 on Nov 15, 2013 2:02:27 GMT 5
Judging from the content, he is talking to you.
BTW, a saltwater crocodile's average is far lower than 15 ft, I have shown the relevant link in the saltwater crocodile vs walrus thread.
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Post by theropod on Nov 15, 2013 22:23:13 GMT 5
I was talking to godzillasaurus
What I mean; You consider it very likely it was differently proportioned, but you give nothing regarding the implications (will it make the animal smaller or larger or change the size at all?).
Without any such data, it is the best bet we have to consider it 3-4m in lenght, not astronomic 5-6m, thus it is roughly comparable to large extant crocodilian species.
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