Ornithischian size

[dinosauria101]

Jan 3, 2020 19:59:12 GMT 5 creature386 said:

Jan 3, 2020 19:55:06 GMT 5 dinosauria101 said:

1: You know what, you do have a point. Closer to 11 tonnes was just a guesstimate; maybe I should say closer to 11-12 to include a wider range of mass

1: You still don't use rounded or guessed numbers if you need the numbers for further calculation.

As for 'both indivoduals', what is the second individual supposed to be?

2: Kelsey

1: So I should only mention the conservative soft tissue and exclusion of parts of the frill AFTER all the scaling is done and add it as a disclaimer that scaling as-is probably underestimates the IRL mass of the animal somewhat?
2: As far as I know, there is no skeletal for Kelsey that has been digitally published. However, this excerpt from the BHI's skeleton cast order catalogue I linked earlier gives 185 cm for the top view width, and I'd think that an order catalogue for a cast of a skeletal would have to be fairly reliable as the people who are ordering the casts need to know the exact dimensions of them, no more and no less, so that they can make just the right amount of space for them.
Here's also that skeletal with the skull separated and given a 2.5 meter scalebar:

[dinosauria101]

Alright, so here's an updated post on Trike's size, with creature's nagging taken into consideration.

As was previously stated, the earlier GDI (link)* gives a Triceratops with a 2.5 meter skull and total length of 8.26 meters a mass of about 10.5 tonnes. And that's not the biggest Trike - the largest specimens would likely have skulls of 2.75 meters (AMNH 5040). Scaling to this increases mass by about 1/3, and thus scaling that Triceratops to specimens such as AMNH 5040 and UCMP 128561 gives a mass of 14 and 13.26 tonnes. In regards to more average sized specimens, scaling down from a 10.5 tonne specimen with a 2.5 meter skull gives ~7.88 tonnes for a Triceratops with a 227 cm skull if we choose to trust theropod on that being average. These mass estimates are a good bit larger than what you would get from using Hartman's or Paul's skeletals. HOWEVER, I have reason to believe that these mass estimates are still probably undersized at least a little bit. The width of the top view of the hyperlinked GDI is about 112 pixels, in contrast with about 162 pixels for the skull length, which would give us about ~173 cm width for the top view. The thing is, a smaller specimen of Triceratops called Kelsey, at 6-7 meters, is actually wider than this at 185 cm wide in top view (here is an excerpt from the BHI's skeleton cast order catalogue which supports that figure, and it's probably a fairly reliable source seeing as the people who are ordering these things need to know the exact dimensions of them, no more and no less, so they can make just the right amount of space). Thus, this 8.26 meter Triceratops has a smaller width than a 6-7 meter one and is therefore almost certainly underestimated in terms of mass. If we choose to go by direct scaling from Kelsey, this specimen would have a width of about 235 cm top view, and as such even 10.5 tonnes would appear to be an underestimate for a Triceratops with a 2.5 meter skull. As for the largest Triceratops specimens, the same would apply; they are just under 187 cm (186.84) wide directly scaling from the GDI as-is, but this also appears to be an underestimate as scaling from Kelsey would give us about 253 cm for the top view-width of these specimens. This would of course also apply to the ~7.88 tonne average that I was able to glean from the skeletal; seeing as the top view is very narrow that is likely an underestimate as well. That's not all - in the original GDI, there is very little soft tissue around the legs, tail, and chest, and the parts of the head in red are excluded from the GDI. This could possibly bump the mass of the specimen with the 2.5 meter skull to 11-12 tonnes. Scaling up that to the biggest specimens gives ~13.85-15.11 tonnes, and scaling down to the supposed average skull length of 227 cm gives ~8.23-9 tonnes - and these are just with the thin top view. These animals would be even larger assuming a top view width (for their dimensions) closer to the ones discussed above.
Note that this is by no means to be taken as factual, guaranteed, or set in stone whatsoever as it is merely a possibility, just like every other mass estimate for every other extinct animal. However, it is entirely possible and on the table that average sized Triceratops specimens were over 9 tonnes, and that the largest got to 14 plus tonnes.

[dinosauria101]

Jan 7, 2020 4:25:30 GMT 5 theropod said:

Link to the post you guys are talking about? Sorry, didn’t follow everything during the last two weeks.

The thing is, I don’t recall broly even giving a proper citation for the ribcage thing. No details e.g. as to how it was articulated, how complete the specimen/reliable the length estimate was, what it’s other proportions were like etc. That should make us consider that there might be good reasons why GSP portrayed the ribcage the width he did.

Here: theworldofanimals.proboards.com/post/53629. This post and everything after it.

I do have the source for the width included, HOWEVER the specimen (USNM 4276) is a bit of postcrania, and the skeletal was by GetAwayTrike - if you ask HIM on DeviantArt, I'm sure he'd be happy to tell you what he based it on.
Regarding the width, Kelsey (13 cm wider than that 10.5 tonne Trike and what lead me to believe that the top view was undersized) seems to have fairly similar proportions to GetAwayTrike's Trikes (198 cm skull and 6-7 meters TL vs 2.7 meter skulls and 9 meters TL). As for reliability, my post should cover that. 
To quote Broly, this is why I find GAT's skeletals better than GSP's. Basically it's because there is absolutely no telling whatsoever what GSP based his skeletal on while there very much is for GAT.

Different head:body proportions in the base reconstructions are the big difference-maker regarding the mass estimate disparity. Greg Paul's version has a proportionally larger skull than GetAwayTrike's versions. He used Greg Paul's T. horridus as-is while I used GAT's version. The advantage in GAT's version is that with GAT, the specimens he uses are quite explicitly stated, but we don't know what specimens Greg Paul used in his version. He was known to make composites of different animals without informing the reader of which assumptions, cross-scaling (if any), and base specimens were used, at all. There is no predicting what his Triceratops is based on or whether it's a multispecimen composite construct or not. Not to mention that GSP did botch things like FMNH PR 2081 and other animals known from good, well-documented remains quite a bit, so between GSP and GAT skeletals, I would take my chances better with GAT skeletals. 

[dinosauria101]

Jan 7, 2020 4:25:30 GMT 5 theropod said:

Link to the post you guys are talking about? Sorry, didn’t follow everything during the last two weeks.
1: dinosauria, you are still posting your Triceratops figures everywhere??? wow.
2: Have you produced any methodology to back up your speculations in excess of what isometric scaling would suggest (13 t), or are you still just making vague "but larger animals get bulkier" claims?
3: And no offense, but he’s an experienced professional, some weirdness in some of his skeletals notwithstanding, and without something more solid than dinosauria’s speculation that he may have composited several specimens AND not done accurate cross-scaling, I’m not going to dismiss them. 
4: On the other hand, I have yet to see any particular reason to prefer "GAT"’s skeletal, which dinosauria is persistently claiming we should do.

1: My UPDATED Triceratops mass figures, quite a bit different than what I got before.
2: I cut the bulk increase entirely. The only things now that give masses in excess of 13.26 tonnes are excluded parts, low soft tissue levels, and a possibly too narrow ribcage. As for skull lengths/proportions again, yes, they could have larger skulls and shorter postcrania. It's also possible they could have proportionately SMALLER skulls and bigger postcrania, thus getting even bigger animals than what my above posts suggest.
TL;DR: If there is a wide range of possibilities, we ought to account for it. My estimations for the very big Trikes could be fairly close to the real thing, they may be oversized somewhat, or they may even be undersized somewhat.
3: That's not my speculation. It's broly's (I agree GSP is often fairly trustworthy on stuff, but his Trike may be one of the chinks in the armor and I think I feel inclined to agree with Broly due to the very low mass this skeletal gives compared to others, as well as the top view which is 154 cm for an 8 meter specimen)
4: Not necessarily; the 2 Trike skeletals I feel are the most reliable are Hartman's and GAT's. You could probably use whichever one of those floats your boat more, and for me it's GAT's. As for reason to use it, the basis is or can be fairly explicitly stated as Broly says, perhaps similar to how the basis of Hartman's skeletal may be fairly explicitly stated and it can work due to that.
Nor do I necessarily claim it should be 100% always used or preferred no matter what. I'm merely showing how it is possible to get reasonable masses for Triceratops that are significantly higher than what many of us on this forum are used to.

[Infinity Blade]

A giant fossil chasmosaurine (Ceratopsidae, Dinosauria) postcranium from Wyoming

The Late Cretaceous (LK) Lance Formation (Maastrichtian) is a well-sampled division from which a variety of vertebrates are known, especially avian and non-avian dinosaur species. A recent expedition by the Missouri Institute of Natural Science (MINS) recovered an incomplete postcranial skeleton (MINS V1036) of an especially large chasmosaurine ceratopsian from Weston County Locality in the Lance Formation of Wyoming. The specimen is represented by cervical, dorsal and caudal vertebrae, a scapulocoracoid, and elements of the pelvic girdle and hind limb. Lack of a skull precludes species alloccation. The remains show morphology consistent with Triceratops, but no postcranial characters distinguish Eotriceratops, Torosaurus, and Triceratops spp. Moreover, the specimen’s extremely large size offers the possibility that it represents a new taxon. Recent studies have reported femur lengths of 1020 mm, 1033.5 mm, and 1104 mm respectively for the LK chasmosaurines Pentaceratops aquilonius (OMNH 10165), Triceratops horridus (AMNH FR 5033), and Triceratops prorsus (USNM PAL 4842). Recent mass estimates suggest that the most robust of these animals, Triceratops horridus, reached 14 tonnes. The preserved part of the femur (lacking its proximal end) in MINS V1036 is approximately 1070 mm long and may be conservatively restored to a length of 1140 mm, which conforms to the expected length based on the complete 1143 mm scapula. The femur is similar in robustness to that of AMNH FR 5033. Based on these proportions, we estimate the mass of MINS V1036 to have been more than 18 tonnes. This would make MINS V1036 the largest known ornithischian, exceeding Shantungosaurus (with a published estimate of 17 tonnes). Although the Lance Formation is a well-studied paleoenvironment, this discovery demonstrates that further exploration offers the opportunity to expand our understanding of the system.

sicb.org/abstracts/a-giant-fossil-chasmosaurine-ceratopsidae-dinosauria-postcranium-from-wyoming/

[dinosauria101]

theropod

As you may or may not have already seen, there was a discussion on your October 2019 estimate for Triceratops size(->) on the Discord (starts July 10->). I figure it might be useful to put some of it here.

Spinoinwonderland said the following:

I think theropod's estimate of 6.4 t for a 227 cm skull might be a bit on the low side as it supposes a 2.7 m skull for a 1.3 cm femur. Scaling Dempsey's skeletal to that skull length gives a ~147 cm femur XD

Same with the estimate of 3.9-4.4 t for a 200 cm skull.

According to razor45dino , the skeletal in question was 12 tons for a specimen with a 140 cm femur (and therefore 257 cm skull). If we were to go off of that, your estimates would go from 3.9-6.4 tons to 5.7-8.3 tons (or in other words, more or less around the 6-8 ton ballpark).

There was also an estimate from that model for a specimen called 'Triceratops albertensis' that came out at or near 14 tons. I will have to ask more about that, however.
EDIT: Yes it was. The skull length estimate Spinoinwonderland mentions is 270 cm, which would indeed give us around 14 tons going off the above - or in other words, right at the size I was so advocative of back in December 2019 lol.