blaze
Paleo-artist 
Posts: 766
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Post by blaze on Sept 11, 2014 21:20:52 GMT 5
I'm still not sold in the fully quadrupedal posture but I saw on twitter a photo from a talk by Nizar Ibrahim, there was more artwork, the color scheme was similar to the milan reconstruction but the proportions were different, it depicted it as a knuckle walker.
Also from twitter, the embargo will be lifted at 2pm EDT (1pm central time, 6pm GMT)
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Post by theropod on Sept 11, 2014 22:23:05 GMT 5
A knuckle walker (kinda like a giant sloth) would actually make sense.
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Post by Grey on Sept 11, 2014 22:42:25 GMT 5
A comment from Holtz on FB :
"Oh, the early press is emphasizing the wrong stuff. The new information is going to blow people away. Many tears forthcoming on Carnviora Forum..."
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blaze
Paleo-artist
Posts: 766
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Post by blaze on Sept 11, 2014 23:01:37 GMT 5
>implying the dinosaurian section of carnivora isn't mostly dead.
The implication of it being the first known true semiaquatic none-avian dinosaur is already pretty big stuff.
Its out
edit:
From the supplementary material, neotype designated
Sigilmassasaurus as a junior synonym.
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Post by theropod on Sept 11, 2014 23:50:33 GMT 5
Seems others always get to everything on this matter before I read of it. Anyway, nothing that would make anyone I know cry. However, many really spectacular revelations, especially that the undersized pelvic girdle and anterior COM (which implies it could not walk bipedally) are real. But it also emphasizes the femur to be robust, so I guess something still doesn’t match up with the picture we saw. Maybe it was really photoshopped as some have speculated? EDIT: The supplement seems to contain quite a lot of information (as it was with K. zabaikalicus, likely more than the actual paper…), I’m gonna have a closer look at it. By the seem of it there’s a small (inferred to be subadult due to size, long bone histology and sutural anatomy) specimen of Spinosaurus with a condylobasal skull lenght of 112cm and a body lenght almost as great as Sue but a femur only 61cm long. But what’s really strange is that the tibia is 110% the femur lenght. One would expect distal shortening, but instead we get elongation? More expectedly, hippo-like lack of medullary cavities in the leg bones and a massive pair of forelimbs!  But it is still possible they are actually lumping individuals of several different-sized specimens into this. Especially the high T/F ratio and the tail seem strange. AND IT SEEMS THEY MADE A 3D MODEL FOR ESTIMATING THE COM, AND YET WE GET NO WEIGHT ESTIMATE?!?!?! |
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Post by creature386 on Sept 12, 2014 0:25:16 GMT 5
AND IT SEEMS THEY MADE A 3D MODEL FOR ESTIMATING THE COM, AND YET WE GET NO WEIGHT ESTIMATE?!?!?! I first hoped you overlooked something… A little note on the paper, I just saw that a Spinosaurus with an 112 cm long skull is (according to their table) almost as long as Sue. One with an 175 cm skull would maybe be close to 50% longer. I believe this is an overestimate, but still, just something I noticed in the table. Oh and many, many thanks for posting! |
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Post by Infinity Blade on Sept 12, 2014 1:00:10 GMT 5
Is Holtz's comment intended to have a bit of a negative connotation?
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blaze
Paleo-artist
Posts: 766
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Post by blaze on Sept 12, 2014 1:02:22 GMT 5
They don't estimate the skull of the milan snout at 175cm, they say that the subadult is 32% smaller so they estimate the skull at roughly 150cm in premaxilla to quadrate.
The neotype preserves partial cervical, dorsal and caudal vertebrae as well as the limb bones and the pelvis, as well as parts of the skull, the proportions are definitely real, I've seen higher resolution images of the mount, the femur is actually robust in there too.
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Post by theropod on Sept 12, 2014 1:22:55 GMT 5
I wasn’t talking about those parts being made up, but maybe two specimens being mixed together–I really can’t make sense of a highly cursorial F/T ratio in combination with an extremely short-legged animal likely not even able to walk bipedally at all.
Anyway, I sort of like the knuckle-walking image of Spinosaurus, it does give the impression of a lumbering swamp giant very different from typical theropods.
Oh, and it appears the nostril position in life actually corresponded to the raised position of the naris, unlike in Diplodocus. The skull-lenght figure referred to Pmx-OcC (but apparently the same is given for PMX-Q) I just noticed, they aren’t interchangeable with the 175cm restored by Dal Sasso et al 2005 for Pmx-Sq in MNSM v4047.
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blaze
Paleo-artist
Posts: 766
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Post by blaze on Sept 12, 2014 1:37:30 GMT 5
They recognize the long tibia and that in other theropods is a sign of cursoriality but that due to Spinosaurus reduced hindlimb that was clearly not was going on with it, however they mention several features of the femur and tibia that resemble what is seen in early cetaceans and modern semiaquatic mammals that use their back legs for paddling, reduced length of the femur is one of them too.
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Post by Grey on Sept 12, 2014 8:42:44 GMT 5
Is Holtz's comment intended to have a bit of a negative connotation? That was a pun, paleontologists seem to laugh at the wars on CF. In another comment Holtz said "yes Tyrannosaurus could take it, on land." Prior to this, he usually said instead that it was depending of which would stroke first, so he changed his mind about this not-so-important question. A bit disappointed that there's no mass estimate but I guess that some will appear in the future days, probably from Cau. In anycase Spino is unique. |
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Post by spinodontosaurus on Sept 12, 2014 16:40:51 GMT 5
Well I missed the initial release of this information, I come online to find Scott Hartman pointing out that the entire pelvic region and hindlimbs on that reconstruction are underiszed by around 27%. |
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Post by theropod on Sept 12, 2014 18:00:10 GMT 5
So it seems like obligate quadrupedalism remains a hypothesis. But I must say in some of the artwork and the reconstruction in question the hindlimbs and pelvis really do look tiny even for a quadruped.
I don’t think that calls into question the conclusion of the paper though, the bone histology and Amiot et al. (2010) on oxygen isotopic evidence are still quite good as evidence for that.
I’m really looking forward to Hartman’s updated skeletal, firstly in terms of limb proportions and secondly in terms of how he interprets the axial elements.
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Deleted
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Post by Deleted on Sept 12, 2014 23:12:27 GMT 5
In anycase Spino is unique. Well, I wouldn't really say that now, Oxalaia and Irritator are very likely similar in form and habits(due to being very close relatives) unless further information states otherwise. Many dinosaurs we once though of as "unique", eventually had others very similar to them discovered later on(for example; Tyrannosaurus and Tarbosaurus, etc. among many others) that didn't make them really "unique" anymore. IMO I don't see a reason why Spinosaurus wouldn't be subjected to the same fate eventually. Only time will tell, of course. |
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Post by theropod on Sept 12, 2014 23:24:20 GMT 5
Every animal is unique in some way, I think that’s what he meant to say.
Of course animals can be very similar, but there’s still a reason they are not all the same species. T. rex is bigger, more robust and has a different skull design compared to Tarbosaurus, and eventually we will likely be able to say the same things about Spinosaurus and other spinosaurines.
If they are completely known, such features will either turn up (most likely) or they will be classified into the same species. That doesn’t mean there were no other animals with a lifestyle and anatomy very similar to Spinosaurus of course, but here the point was rather how unexpectedly different spinosaurines as a whole were from other theropods (I think). Of course the last one should already have been widely recognized before the neotype got described, quadrupedality or not.
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