Largest sauropods

[Fragillimus335]

Jun 30, 2013 22:03:36 GMT 5 Grey said:

Fine with this. But I spit on the establishment of any fact from this, including fragillimus post in deviantart "255 tons and the largest animal ever to live".

Don't spit on anything just yet. Just from flat out isometric scaling a diplodocus-like animal with a 2.7 meter vert makes it 2.7m/1m=2.7

2.7x26.25=71 meters long and 2.7^3=19.7 19.7x11.5=226 tons. So yes I overestimated the old weights by a bit, I think it was because I counted allometric neck growth and cartilage as a cubed factor, and not a linear one. So no, I don't treat sauropods in excess of 250 tons likely at this point.

[Grey]

This post being one year old, I was thinking you may had improved your reasonning here.

[Life]

I admit, this thread contains lot of interesting information but the discussion have heated (beyond comfort zone) on several points as well. The key to avoid such confrontations is to use words such as speculation, loose estimation, reliability in question, outlier, high error range and vice versa.

Such words can be put in tag forms as well like following:

Example: [Speculation starts] information [Speculation ends]

Example: [Loose estimation starts] information [Loose estimation ends]

Example: [Reliability in question starts] information [Reliability in question ends]

Example: [Outlier starts] information [Outlier ends]

Example: [High error range starts] information [High error range ends]

In this manner, potential critics would also know that the stated information (whose reliability is in doubt or is bad science) is being identified as such.

So I advice all fellow members to follow this kind of argument pattern in case of posting sensitive or questionable data.

Also, refrain from posting insulting remarks. Thank you.

[theropod]

^Such terms and definitions have been used, but sadly misinterpreted, and often there were mainly exageratedly harsh words and rebuttals here.

[blaze]

I’ll rehash some posts I made some time ago on cf; I think they are very important points to have in mind if A. fragillimus is mentioned again. Vertebral height is a very unreliable measure, case in point, the D10 of “seismosaurus” is actually around 1.3m tall (Herne & Lucas, 2006), 21% more than the D10 of Diplodocus CM84 however, fasten your seatbelts, is estimated that its centrum length is only 280mm, less than the 290mm of CM84. If you don’t trust this because the measurements are estimates (because “seismosaurus” D10 was still in preparation) then let’s use a prepared vertebrae of seismosaurus and its corresponding counterpart in CM84.

Dorsal 8
Centrum greatest length
P3690 300mm
CM84 275mm
difference: 9%

Centrum greatest width at caudal end
P3690 400mm
CM84 309mm
difference: 29.4%

Vertebral total height
P3690 1260mm
CM84 847mm
difference: 48.8%

The D8 of "seismosaurus" is almost 50% taller than the D8 of CM84 but the centrum is 30% wider and only 9% longer. What if we use the D3 instead? "seismosaurus"'s is ~40% taller than CM84's, but that of the later has centrum that's actually 4% wider and 9% longer, that's right, the D3 of Diplodocus CM84 is 9% longer than the D3 of “seismosaurus". The point is that even if the vertebrae is a perfect match in the anterior/posterior view it doesn't mean that the whole vertebrae is a perfectly scaled replica, if we only had a drawing of the anterior/posterior view of the D8 of “seismosaurus” in similar conditions to that of A. fragilimus, we would be saying it was 40m long and yet the whole animal was actually 29-30m (from Lovelace et al., 2007 and Hartman’s estimate) so only 11% bigger in linear dimensions than CM84. By this example A. fragillimus might have a vertebra that was indeed 2.7m tall but in the end its centrum length would only be 420mm (or 44% bigger) instead of the 710mm (250% bigger) suggested by a perfect isometric scaling from CM84, meaning the animal's only ~40m long. Now this is not an estimate I’m providing, is just to show you how massive the error bars are in using a single measure of a single vertebra. When the error bars can produce mass estimates spanning two orders of magnitude… what reason is there to use that estimate at all?

Now before someone comes and tells me that “seismosaurus” has taller neural spines, no, that’s only a feature of the sacral and caudal vertebrae. It is true that "seismosaurus" has proportionally taller dorsals compared to centrum length by about 15% (mean ratio of 3.3 vs 3.8) but as you can see below this is not caused by taller neural spines, the vertebrae is just not as long as it is tall and who is to say that the A. fragillimus vertebrae didn’t continue that trend? I really don't care, I'll also choose to ignore this sauropod but I'll like if people had this in mind, I read the whole thread and throughout all the discussion on its size no one touched this very important point.



Edit: I think I used the wrong view for the Diplodocus vertebrae... it doesn't affect that much the comparison though.

Edit2: Updated size chart, there are some little inconsistencies with the illustrations and measurements but is doubtful that this will impact the main objective of the size chart, that "seismosaurus" doesn't have proportionally taller neural spines than CM84.

[Fragillimus335]

Wow, some measurements must be off! Because your image contradicts all those statements. When the seismo and dippy verts are scaled to the same height they have nearly the same centrum length!!! MYDD!!!

Amphicoelias will rise AGAIN!!! Hehe, just kidding.


(Measure you damn dinosaur!!!)

[theropod]

blaze: Where are the illustrations from?

[blaze]

Herne & Lucas 2006. Seismosaurus halloroum: Osteological reconstruction from the holotype

and

Hatcher 1901. Diplodocus (Marsh): Its osteology, taxonomy and probable habits, with a reconstruction of the skeleton.

[theropod]

Thanks!
Any idea where to find a pdf for the second one?

PS: The vertebral height of D. hallorum seems consistent with the figures you get from using dippy (60-70m for 2.3-2,7m and the according weights based on Diplodocus), so this is indeed a simple scaling error that should be corrected.

[creature386]

Finding a more than 100 year old paper is very hard, I don't know if there even is a free access pdf.

[theropod]

Finding a pdf at all is maybe asking for too much...

[creature386]

The best would be to ask if he can send it to you.

[blaze]

You're welcome, gentlemen.

Diplodocus (Marsh) : its osteology, taxonomy, and probable habits, with a restoration of the skeleton. By J. B. Hatcher.

It's on the Biodiversity Heritage Library.

theropod
Maybe, though the estimates of 29-30m for Seismosaurus were first proposed a year after Carpenter's paper was published, the paper from where I got the height of siesmosaurus vertebrae is on the same volumen as Carpenter's paper, Herne & Lucas (2006) they said that the length of the mount is 32.8m but they acknowledge a possible 10% error in either direction in the sculpting of the bones, giving a range of 30-35m, Carpenter could have known of this and used "seismosaurus" dimensions instead. I'm fine with that, is not like he said he was scaling up from CM84 and "seismosaurus" is just a big diplodocus.

[theropod]

Thank you soooo much!

A 10% error bar in either direction is not unusual, we can of course derive a range based on this, but it will center around the same figure (lower figure 54-63m, upper figure 64-75m). Would the different lenghts greatly affect weights or would it mainly just be a change in tail/neck lenght?

[blaze]

I think it would be only tail/neck length that would be affected.