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Post by spinodontosaurus on Dec 22, 2013 8:32:04 GMT 5
Old habits and themes die hard - it's been implanted in peoples' minds for a long time that females were bigger. Whilst a small portion of enthusiasts will find that this isn't particularly likely, it would take another top-quality and popular documentary series to get it into public knowledge (something that is pretty badly needed - most people seem to run on information that was sort of accurate back in 1997).
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Post by Deleted on Dec 22, 2013 8:50:21 GMT 5
Old habits and themes die hard - it's been implanted in peoples' minds for a long time that females were bigger. Whilst a small portion of enthusiasts will find that this isn't particularly likely, it would take another top-quality and popular documentary series to get it into public knowledge (something that is pretty badly needed - most people seem to run on information that was sort of accurate back in 1997). Yeah, WWD seems to be among the most influential source for paleo enthusiasts. Even that ~150-tonne Liopleurodon nonsense is still widely-believed. |
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Post by creature386 on Dec 22, 2013 15:32:28 GMT 5
Even with an influential documentary, it will take a long time, because all the old and retarded books still exist.
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Post by theropod on Dec 22, 2013 18:43:11 GMT 5
I think Hartman was more likely talking about mass. His Spinosaurus holotype is over 1.5m longer than FMNH PR 2081 and MUCPv-ch1, and still almost a metre longer than MUCPv-95. He doesn't necessarily have to have performed a GDI for that, I'm sure he's fully aware of the estimated masses for other spinosaurs and of the bulk of this specific one.
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Post by creature386 on Dec 22, 2013 20:34:55 GMT 5
What we should keep in mind when reading this is that nobody is really doubting that the type specimen is among the largest theropods - even Cau (I think? He only seemed to be arguing it wasn't the biggest, and besides it's vertebrae are still as big as Acrocanthosaurus', which is definitely a very large theropod. At least that's the impression I got). Even 6 tonnes as Blaze mentioned puts it close in size to the Giganotosaurus type specimen and various Tyrannosaurus specimens - I would call that being in the same 'size class' myself, as I would if higher estimates of 8 tonnes+ are true. Even if it had a lower mass (or a length of only 12,5 m), it would dimensionally still be among the largest theropods. So, yeah, we can agree that it was definitely among the biggest. |
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Post by theropod on Dec 22, 2013 21:14:44 GMT 5
Cau seemingly assumes it's 4t ("half the weight of Sue"), which is very far from the largest theropods-despite it being in the same lenght class which he really didn't doubt (he merely claims no Spinosaurus above 13m existed...).
Of course there are many problems with the approach that even makes him think it must be half T. rex' weight, most are familiar with the vast differences in morphology and ecology and the whole femur-diameter-problematic as a brilliant example of this.
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Post by creature386 on Dec 22, 2013 21:18:40 GMT 5
I was talking about how it would look dimensionally.
Cau assumed a similar mass for Acrocanthosaurus, and we don't know about the exact figures he favors (we don't even know if he claims Sue to weigh 8 t).
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Post by Grey on Dec 22, 2013 21:25:16 GMT 5
Cau does not like to give precise weight estimates, he favors range. He describes Spinosaurus and Tyrannosaurus to have been 5-10 tonnes theropods. Only, he strongly suggests that Spinosaurus was much lighter especially at length parity. We can then assume in his view Spinosaurus to be nearer to the lower bound, Tyrannosaurus nearer to the higher bound.
He never said that Spinosaurus is not one of the largest theropod, this is obviously not disputable.
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Post by theropod on Dec 22, 2013 21:34:19 GMT 5
He did claim Spinosaurus was half the weight of Tyrannosaurus.
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Post by Grey on Dec 22, 2013 21:37:56 GMT 5
Can you link this ?
He does not suggest at length parity ? It is true that its vertebras and its snout are very gracile compared to those in Tyrannosaurus...
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Post by theropod on Dec 22, 2013 21:45:08 GMT 5
Well, he does believe they were at lenght parity, doesn't he? theropoda.blogspot.it/2013/11/vertebre-dorsali-di-theropodi-confronto.htmlIt may be 3t, or 4t, or 5t, but in any case half remains half. The example of Acrocanthosaurus he showed himself should suffice to shed doubt on those figures tough. Anyway, even assuming the holotype was 46% of T. rex size, MNHM should be at least 79%, but more likely 155%. His own comparisons don't seem consistent with that tough, as broly demonstrated earlier. |
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Post by Grey on Dec 22, 2013 21:54:06 GMT 5
Interesting to see he mentions the vertebra of a large carcharodontosaurid under study...
Well, this remains only based on the vertebra size, there are other factors to keep into account. Half the weight of T. rex might be a bit extreme, but viewing these vertebra it makes sense Spinosaurus was lighter at parity. My gut feeling is at 6 tonnes, more if it was way longer (longer tail, sail/hump). This does not change that Spinosaurus was an extremely big theropod.
On another post, he said what he thinks of Hartman depiction :
"Scott's skeletal reconstructions are very good. Nevertheless, and I think Scott himself is aware of this, the accuracy of a Tyrannosaurus or Allosaurus skeletal reconstruction is higher than that of a Spinosaurus. The former taxa are based on multiple and well preserved specimens, Spinosaurus is based on just a bunch of specimens, with the most complete of them now lost. You cannot trust a Spinosaurus skeletal the same way you trust a Tyrannosaurus or Allosaurus skeletal, regardless to the accuracy and skillness of the author of the artwork.
Personally, I think his Spinosaurus is too bulky and heavy in the ribcage: as I showed in a recent post, based on the available data, Spinosaurus ribcage results more shallower and narrower than Tyrannosaurus."
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Post by Grey on Dec 22, 2013 21:56:11 GMT 5
And confront him you guys instead of express your disagrements and "frustration" here only.
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Post by coherentsheaf on Dec 22, 2013 22:21:33 GMT 5
Cau does not like to give precise weight estimates, he favors range. I am always at a loss when someone like Cau, who presumably has basic training in statistics makes statements like these. Giving a range is exactly as imprecise as giving a point estimate, often times it is harder. What is the 95% confidence estimate for Sue and based on what method? Givig ranges without methodology seems like going from bad to worse. What someone can say from resaonably complete specimen like Sue is imprecise, I agree, but telling yourself a point estimate is therefore inferior to a range is ludicrous. What I can agree on is giving multiple estimates based on different methods. But even then giving a range is hard. And some of these methods will be inferior, like taking a single bone dimension as basis for comparison. |
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Post by Grey on Dec 22, 2013 22:40:45 GMT 5
At first, I don't like Cau that much (and would there be a problem with it ?).
Then, it is of course, much more cautious to claim that this A Tyrannosaurus weighed 5-8 tonnes than an exact 6 873 kg. Just based on what you say, on different methods. Cau does not rely on one estimate or one range, but on all the published reasonnable figures. You just have to read his posts for understand this.
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