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Amphicoelias skeletal reconstructions by SpinoInWonderland Amphicoelias skeletal reconstructions by SpinoInWonderland
Skeletal reconstructions of the two known specimens and species of Amphicoelias. Yes, Amphicoelias fragillimus is probably just the adult form of A. altus. And no, it probably wasn't a scaled-up Diplodocus clone. And no, I don't think it was a big rebbachisaur either. Tschopp and Mateus' 2015 specimen-level analysis of diplodocoids places A. altus as a basal flagellicaudatan.

(As of February 2017, after rereading Carpenter's 2006 paper and looking at pictures of their dorsals and comparing them and other diplodocids, and the unfused scapulacoracoid used to infer AMNH 5764's alleged immaturity probably not really belonging to Amphicoelias at all, I finally decided to split A. fragillimus as it's own species once more.)

The dorsals are based on Supersaurus lourinhanensis and Diplodocus, while the tail and neck are based on Supersaurus vivianae.

The skull and feet are based on Diplodocus, while the limb proportions and girdles are based on Tornieria. The sacrals are based on Apatosaurus.

AMNH 5764's left and right limbs have been swapped, since the complete right femur would have been obscured in favor of the incomplete left femur otherwise. AMNH 5777's size is based on my estimate for the total size of it's vertebra, assuming that Cope's neural arch represented the whole height of the neural arch above the neural canal and without the spine's "head".

Gastralia was inferred from Jobaria, Diamantinasaurus, and diplodocoid gastralia from the Howe Quarry (morphotype D, Tschopp & Mateus, 2012).
____________

Measurements for AMNH 5764:

Hip height: ~3.7 meters

Shoulder height: ~3.96 meters

Back height: ~4.35 meters

Total height: ~8.38 meters

Tip-to-top total length: ~18.26 meters

Axial length: ~20.5 meters
__

Measurements for AMNH 5777:

Hip height: ~8.67 meters

Shoulder height: ~9.28 meters

Back height: ~10.2 meters

Total height: ~19.64 meters

Standing length: ~42.8 meters

Axial length: ~48 meters
____________

References/sources:

Osborn & Mook, 1921, "Camarasaurus, Amphicoelias, and other sauropods of Cope"
Woodruff & Foster, 2015, "The fragile legacy of Amphicoelias fragillimus"
Carpenter, 2006, "Biggest of the big: a critical re-evaluation of the mega-sauropod Amphicoelias fragillimus"
Janensch, 1961, "
Die Gliedmaszen und Gliedmaszengürtel der Sauropoden der Tendaguru-Schichten"
Hatcher, 1901, "Diplodocus (Marsh): it's osteology, taxonomy, and probable habits, with a restoration of the skeleton"
Lovelace & Hartman, 2007, "Morphology of a specimen of Supersaurus (Dinosauria: Sauropoda) from the Morrison Formation of Wyoming, and a re-evaluation of diplodocoid phylogeny"
Bonaparte & Mateus, 1999, "
A new diplodocid, Dinheirosaurus lourinhanensis gen. et sp. nov, from the late Jurassic beds of Portugal"
Osborn & Granger, 1901, "Fore and hind limbs of sauropods from the Bone Cabin Quarry"
Tschopp & Mateus, 2015, "A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda)"
Tschopp & Mateus, 2012, "Clavicles, interclavicles, gastralia, and sternal ribs in sauropod dinosaurs: new reports from Diplodocidae and their morphological, functional, and evolutionary implications"
Remes, 2006, "Revision of the Tendaguru sauropod Tornieria africana (Fraas) and it's relevance for sauropod paleobiography"
Apatosaurus sacrum

__________

UPDATE(11/7/2016): Came up with a new vertebral reconstruction for the A. "fragillimus" specimen. The previous
vertebral reconstruction is my "best fit" estimate which assumes that the adult and juvenile had the exact same neural arch proportions.

This looked fine for a while, but when I actually tried estimating mass based on GDI, it ended up at approximately ~220 tonnes with a density of ~0.8 and without limbs. I realized that this could be a bit problematic, so I made one extra assumption, which is that Cope's neural arch represented the whole height of the neural arch minus the spine "head" and the neural canal, which, while not really impacting the overall appearance, downsized the adult a fair bit. See the previous version for comparison.

Previous measurements: ~10.7 meters hip height, ~11.4 meters shoulder height, ~12.3 meters back height, ~22.7 meters total height, ~47.5 meters standing length, ~53.3 meters axial length

UPDATE(2/12/2017): Apparently, according to Tschopp and Mateus (2015), the scapulacoracoid originally assigned to the Amphicoelias altus holotype probably did not belong to Amphicoelias at all, but rather a camarasaurid. Thus, it needed a revision and the scapulacoracoids were replaced by Brontosaurus-based ones scaled based on the scapulacoracoid:femur length ratio present in Brontosaurus louisae specimen CM 3018.
Previous version

Previous measurements: ~4.4 meters shoulder height (A. altus AMNH 5764), ~10.3 meters shoulder height (A. fragillimus AMNH 5777)

UPDATE(2/17/2017): Fixed a layering order issue in the cervical-dorsal transition, and added detail to the isolated D10 lateral and posterior views.

UPDATE(5/11/2017): Revised the limbs and girdles based on extra data I received about Tornieria, fixed the pubis articulation, revised the dorsal neural arches based on Diplodocus carnegii (which fits in better with the A. altus dorsal neural arch), and removed the assigned ulna. The changes and fixes to the limbs and girdles tilted up the dorsal column as an effect, but height still decreased overall due to the shorter limbs. Also added the distal femur mentioned in Cope's field notes to the A. fragillimus skeletal (in light gray). See the previous version for comparison.

Previous measurements:
AMNH 5764: ~4.15 meters hip height, ~4.17 meters shoulder height, ~4.75 meters back height, ~8.78 meters total height, ~18.37 meters standing length
AMNH 5777: ~9.7 meters hip height, ~9.78 meters shoulder height, ~11.1 meters back height, ~20.6 meters total height, ~43.1 meters standing length

Add a Comment:
 
:iconpaleo-king:
Paleo-King Featured By Owner Jan 11, 2018  Professional Traditional Artist
One fine jurassic day there was a time warp. Somehow an Apatosaurus ajax met a Galeamopus hayi, they had a very primitive love child with all sorts of throwbacks, and it was named Amphicoelias.
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:iconspinoinwonderland:
SpinoInWonderland Featured By Owner Jan 11, 2018
LOL. Given it's basal position in Tschopp et al. (2015), I wouldn't be surprised if that's (Apatosaurus+Galeamopus love child) what it actually turns out to look like :D (Big Grin) 
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:iconrizkiusmaulanae:
RizkiusMaulanae Featured By Owner Aug 6, 2017  Student Traditional Artist
Any chance you'll revising this ?
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:iconspinoinwonderland:
SpinoInWonderland Featured By Owner Aug 7, 2017
In time.

I may need to wait for Tschopp's assessment of Amphicoelias' position.
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:iconlapwing30kph:
lapwing30kph Featured By Owner Jul 8, 2017
I read somewhere that the estimate of the 1500mm portion of one of Amphicoelias fragillimus's back vertebrae was a typo--the correct measurement was 1050mm.  This means that A. fragillimus's complete vertebrae would have been about 5.5 feet in height, and based on this, here is what I estimated for the dinosaur's size (based on Diplodocus):

OVERALL LENGTH: 136.125 feet

LENGTH OF NECK: 34.5 feet

HIP HEIGHT: 18.5 feet

WEIGHT: 70 tons

Based on its 19-foot skull, a blue whale must typically be about 76 feet long and 90 tons in weight.  Still, Amphicoelias was the biggest land animal that ever lived.
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:iconspinoinwonderland:
SpinoInWonderland Featured By Owner Jul 8, 2017
The typo hypothesis is historically unsupported and speculative, as admitted in the paper that proposes it itself.
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:icondinosaurlover83:
Dinosaurlover83 Featured By Owner May 10, 2017  Student Artist
Niice. Been looking forward to a skeletal of these for a while :)
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:iconbraindroppings1:
Braindroppings1 Featured By Owner May 10, 2017  Hobbyist Traditional Artist
Nice job!
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:icondinopithecus:
Dinopithecus Featured By Owner May 2, 2017
So...a new publication places A. altus in Apatosaurinae...

peerj.com/articles/3179/

This placement is dubious (as they note), but just wanted you to hear about this.
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:iconspinoinwonderland:
SpinoInWonderland Featured By Owner May 2, 2017
There's another upcoming analysis to better get a placement for Amphicoelias.

For now, I think this would be updated with new data I got about Tornieria but that's about it.
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:icondinopithecus:
Dinopithecus Featured By Owner Feb 13, 2017
With all your updates, how massive is the beast now?
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:iconspinoinwonderland:
SpinoInWonderland Featured By Owner Feb 18, 2017
The new GDI is up now (it just replaces the older one in the GDI sharing journal).

It didn't drop as much as I thought it would, the width needed no change because it's already scaled via the width of the diapophyses compared to the ribcage. A. altus ends up at ~14.7 tonnes (the new result is a bit lower than the old one, but rounding to the first decimal place obliterates the difference there) while A. fragillimus ends up at ~189 tonnes.
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:iconspinoinwonderland:
The last GDI yielded about ~14.7 tonnes for A. altus and ~189.7 tonnes for A. fragillimus using an SG of ~0.85, but since the latest update shrank the torso, then their masses will go down at least a bit. I'll have to redo the graphic double integration sometime.
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:iconpaleosir:
paleosir Featured By Owner Sep 5, 2016  Hobbyist Traditional Artist
interesting revision!
turned out pretty weird huh?
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:iconspinoinwonderland:
SpinoInWonderland Featured By Owner Sep 5, 2016
Well, not as weird as some of those crazy sauropod forms out there, but it did turn out deeper-bodied, taller, and bigger-hipped(?) than usually though.
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:iconpaleosir:
paleosir Featured By Owner Sep 5, 2016  Hobbyist Traditional Artist
yes, I meant weird compared to the traditional approach

indeed, some sauropodomorphs are weirder
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:icondinopithecus:
Dinopithecus Featured By Owner Edited Aug 3, 2016
Okay, since this has good ol' Amphicoelias, the famed giant sauropod, I wanted to ask you something about adaptations for size.

On Carnivora, someone brought up the vertebrae of a mammal called the hero shrew.

Looking at the adaptations it has (like a very strong spine, thick ribs, reduced abdominal muscles, enlarged spinal muscles, as mentioned in the Wikipedia article), he thought that if a mammal that the vertebrae of a hero shrew it could possibly grow ten times heavier than an elephant. Does this seem like a sound notion?

Here's the Carnivora topic if you're interested.
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:iconspinoinwonderland:
SpinoInWonderland Featured By Owner Aug 3, 2016
Well, I don't think so.

First of all, sure you can overengineer the vertebrae as much as you want, but if the legs can't take it, then it's not a functional form.

Secondly, it's not structural strength that limits the size of terrestrial mammals - it seems that a combination of chewing and the way mammals reproduce prevent land mammals from reaching the whale-level sizes that sauropods did.

Seems like people still put too much stock into that idea that biomechanical factors are actually relevant in limiting animal size :rolleyes: revamp 
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:icondinopithecus:
Dinopithecus Featured By Owner Edited Feb 13, 2017
Heh, you know, I actually realized something. The hero shrew's vertebrae are meant to be very flexible sagitally, but if you're a giant animal, don't you want your vertebrae to be less flexible in that plane in order to bear your weight better? Also, skeletal muscles experience fatigue with time; having them support your weight, as opposed to some sort of passive support, wouldn't exactly be great if you want to be a hypothetical terrestrial megamammal as big as a whale, no?

Seems like the spine of a hero shrew would actually be a horrible adaptation for being giant XD.
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:iconspinoinwonderland:
SpinoInWonderland Featured By Owner Feb 13, 2017
Yeah, it's just not built to be huge.
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:iconrandomdinos:
randomdinos Featured By Owner Aug 3, 2016  Hobbyist Traditional Artist
Well, they certainly are relevant, otherwise sauropods wouldn't have evolved many remarkable biomechnical adaptations for more efficient circulatory systems, feeding etc. They just aren't a reeally major reason, much less the only one as some believe.
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:iconspinoinwonderland:
SpinoInWonderland Featured By Owner Aug 3, 2016
That's more of biomechanical factors limiting animal form (many animal forms just don't scale well that far).

The biomechanical limits I'm talking about limit animal size as a whole, and that limit is too high to be relevant.
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:iconfragillimus335:
Fragillimus335 Featured By Owner Aug 2, 2016  Hobbyist General Artist
Cool skeletal, the height and limb proportions are very interesting! I must ask, why do the cadual verts decrease in size so drastically? Even supersaurus with its shorter than average tail has a cadual series half of its total length.  A quick measure puts your skeletal at ~29 meters from head to ilium, and the tail at only 22.5 meters.  The tail also seems to have a very dramatic reduction post sacrum, which doesn't seem to be the case in other diplodocids.
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:iconspinoinwonderland:
SpinoInWonderland Featured By Owner Aug 2, 2016
The tail and neck are based on the Supersaurus from Lovelace & Hartman's 2007 paper, scaled to match the centrum height of the last dorsal.

The dramatic tapering of the tail is due to those big hips and deep torso, the tail is a normal diplodocoid one otherwise.
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:iconfragillimus335:
Fragillimus335 Featured By Owner Aug 3, 2016  Hobbyist General Artist
Strange, when I scale Supersaurus to have a ~2.8 meter last dorsal its tail is 31 meters long, almost ten meters longer than your reconstruction.  The depth of the tail is also 3.2 meters vs your 2.1 meter depth post pubis. (not counting flesh envelope)
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:iconspinoinwonderland:
SpinoInWonderland Featured By Owner Aug 3, 2016
I scaled using centrum depth, not total height.
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:iconfragillimus335:
Fragillimus335 Featured By Owner Aug 17, 2016  Hobbyist General Artist
But why centrum depth vs total height? Its the only part of the vertebra that is complete guesswork for A. fragillimus.
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:iconspinoinwonderland:
SpinoInWonderland Featured By Owner Aug 18, 2016
"But why centrum depth vs total height?"

Amphicoelias has proportionally larger neural arches than many other diplodocoids.



"Its the only part of the vertebra that is complete guesswork for A. fragillimus."

The centrum depth is just as much guesswork as the total height is.
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:iconfragillimus335:
Fragillimus335 Featured By Owner Aug 4, 2016  Hobbyist General Artist
oh, I see.
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:iconafrovenator:
Afrovenator Featured By Owner Aug 1, 2016
The femur is reversed. Aside from that, great work! 
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:iconspinoinwonderland:
I kinda overlooked this...

I'll fix it as soon as possible.

EDIT: It's fixed now :) (Smile) 
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:icondinopithecus:
Dinopithecus Featured By Owner Aug 1, 2016
The tail starts to taper more proximally than I thought. Hence, it looks more unusual than I imagined.

Great work.
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:iconspinoinwonderland:
SpinoInWonderland Featured By Owner Aug 1, 2016
That's just due to the big hips. The tail's a normal diplodocoid one :) (Smile) 
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:icontheropod1:
theropod1 Featured By Owner Aug 1, 2016  Student Traditional Artist
Great work! Also an impressive demonstration on the size difference between the two.
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:iconkirkseven:
kirkseven Featured By Owner Jul 31, 2016
Any weight Estimates?
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:iconspinoinwonderland:
SpinoInWonderland Featured By Owner Jul 31, 2016
None right now, but I guess between around roughly ~125-175 or so tonnes for the adult based on scaling a 30ish-meter blue whale next to it.
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:iconkirkseven:
kirkseven Featured By Owner Edited Aug 1, 2016
Cool! My guess is about 170 tonnes based on your skeletal.

I think blue whales average 90-130 tonnes (depending on the region)

But the very largest blue whales exceeded 200 tonnes.
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:iconspinoinwonderland:
Average southern blue whales are ~24.7 meters long and ~92.7 tonnes in mass according to this paper. IIRC, southern blue whales are a little bit larger than northern ones on average, so the northern average may be a bit smaller. The record-sized obese fatty blue whales massed at ~190 tonnes, there's nothing about 200+ tonne blue whales AFAIK.
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:iconkirkseven:
kirkseven Featured By Owner Aug 1, 2016
well most listed sizes for blue whales are estimates anyway so we don`t know for sure.

scaling from your 24.7 meter 92.7 tonne size figure the longest blue whale

(which is 33.6 meters long for the record) yeilds a weight of 233.35 tonnes
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:iconspinoinwonderland:
SpinoInWonderland Featured By Owner Aug 1, 2016
IIRC, large rorquals don't scale isometrically, the blue whale is actually less massive than what isometrically scaling from smaller whales suggests.
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:iconkirkseven:
kirkseven Featured By Owner Aug 1, 2016
But how much Smaller?
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:iconspinoinwonderland:
SpinoInWonderland Featured By Owner Aug 2, 2016
I don't know the exact way rorquals scale.

For what it's worth, a minke whale (~7-8 meters and ~4-5 tonnes on average) scaled up to the length of the average blue whale would mass around roughly ~150-175 tonnes.
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(1 Reply)
:icondinopithecus:
Dinopithecus Featured By Owner Aug 1, 2016
Not necessarily doubting you but do you know what source says that 33.6 meters is the record length?
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:iconkirkseven:
kirkseven Featured By Owner Edited Aug 1, 2016
www.extremescience.com/blue-wh…
www.registrelep-sararegistry.g…

there are other sources (that i cant seem to find) that say this.

ill keep looking, sorry if they aren't reliable.
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:icondinopithecus:
Dinopithecus Featured By Owner Aug 2, 2016
I'm not sure if the first link is something I'd trust. Second one, maybe, but I'd still be cautious.
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:icondinotasia123:
DINOTASIA123 Featured By Owner Jul 31, 2016
People tend to forget about this guy, but I think this guy needs more attention
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:iconspinoinwonderland:
SpinoInWonderland Featured By Owner Jul 31, 2016
Definitely. We also need more fossils of it to finally resolve the issue.
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:icondinotasia123:
DINOTASIA123 Featured By Owner Aug 1, 2016
Indeed
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:iconpaleojoe:
PaleoJoe Featured By Owner Jul 31, 2016  Student Digital Artist
This reconstruction is indeed very informative and I need not say massive, also though it's very basal it looks most like Brontosaurus excelsus. I am excited to read your size estimations for both specimens.
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