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Abydosaurus mcintoshi skeletal

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Abydosaurus mcintoshi

Etymology: "Jack McIntosh's Abydos lizard" (after the Egyptian site of Abydos, in reference to burial of the head and neck and its significance to one of the Osiris myths - and John "Jack" McIntosh, prolific researcher at Dinosaur National Monument and a giant of sauropod paleontology for several decades)

Time horizon: Early Cretaceous, Albian epoch (~104 mya)

Length: ~29m (~96 ft.)

Probable mass: 55+ tons

*NOW UPDATED with corrections to the tail base and pubes*

The recently discovered (but never before completely restored) cretaceous brachiosaur Abydosaurus. This was, at least judging by the juvenile holotype skull, a rather sharp-toothed animal by brachiosaur standards. The teeth were narrower than in earlier brachiosaurs, and converged on somphospondylian tooth design (probably in adaptation to newly evolved conifer types in the Cretaceous). The dig site is, believe it or not, a vertical cliff face at the famed Dinosaur National Monument near Jensen, Utah. However it's in higher and younger rock layers than the old visitor center (which was built around Morrison formation/Late Jurassic fossils), being from the Cedar Mountain formation of the Early Cretaceous (Mussentuchit Member/Albian epoch, making it one of the last known EK brachiosaurs in North America). There are partial remains from at least five and possibly as many as seven individuals buried at the site, including three skulls and a fragment of a fourth, and perhaps even individuals may be hidden deeper in the cliffside. The stone surrounding the bones of this supposed "family group" was extremely hard, and combined with the steep incline of the matrix, this made Abydosaurus one of the most difficult sauropod digs in recent years. We're talking dynamite and jackhammers here, not scrapers and brushes.

Much of the material still awaits preparation, and the best gauge of the sizes of the various individuals is still the field map supplement included with the description paper. The adorable little holotype skull is one of the best-preserved and most complete sauropod skulls in existence, with all the teeth in place and including even the rare hyoid bones in the throat, and some of the sclerotic ring material in the eye sockets.

Although Abydosaurus is usually thought of as a small or midsized brachiosaur with an unusually small nose for its lineage, this is because the only specimen that seems to get any attention in the media is the holotype, a young animal with a typically small juvenile nasal arch. In fact the referred specimens are all larger, and the really big ones haven't even been assigned a catalog number as of the description's publication date.

The largest individual is known from a few downright colossal rib fragments, which are scaled rather conservatively here to correct for possible crushing which may have artificially widened them. And keep in mind that scaling a sauropod off of rib material, when it's larger than the more complete specimens, is fraught with allometric proportion problems due to ontogeny (the scapula and coracoid also change proportions at different stages in the growth series). Even so, this "adult" specimen seems to have been extremely large, easily pushing 100 feet and rivaling Sauroposeidon in dimensions.


References:

Chure, Daniel; Britt, Brooks; Whitlock, John A.; and Wilson, Jeffrey A. (2010). "First complete sauropod dinosaur skull from the Cretaceous of the Americas and the evolution of sauropod dentition". Naturwissenschaften 97 (4): 379–391.

(despite being published in Springer, the paper and its supplementary material is open-access and free - though who knows for how long).
Image size
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Comments42
anonymous's avatar
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Majestic-Colossus's avatar
Fantastic creature and a lot of information! :) (Smile) 
SameerPrehistorica's avatar
SameerPrehistoricaProfessional Digital Artist
Seems like so far this dinosaur has the tallest shoulder height, taller than Argentinosaurus/Puertasaurus.
Paleo-King's avatar
Paleo-KingProfessional Traditional Artist
The Potter Creek brachiosaur may be in the same range as these guys for shoulder height. And yes, having a 90-foot brachiosaur will do insane things for shoulder height. Things that even the really big titanosaurs can't top - they usually have much flatter backs anyway. Just imagine, the type specimens (and the mounts derived from them) for Brachiosaurus and Giraffatitan are already far bigger in volume than ANY mounted diplodocid skeleton - and yet NEITHER of them tops 85 feet in length, and neither one is fully grown. The biggest mounted dinosaur exhibits with ACTUAL BONES aren't even adults, and don't even hit 90 feet in length. Imagine how tall the Potter Creek brachiosaur must be, or for that matter HMN XV2/Fund no. when it was alive. Both with a total body length roughly equal to a diplodocus. But with many times the height and volume.

Even Abydosaurus may have a run for its money.
SameerPrehistorica's avatar
SameerPrehistoricaProfessional Digital Artist
What is your opinion on the short leg theory for argentinosaurus based on dreadnoughtus ? I saw few pictures of argentinosaurus having short legs which gives a shoulder height of 20 ft. I guess you might have seen any one of those pictures.
Paleo-King's avatar
Paleo-KingProfessional Traditional Artist
I do not think Argentinosaurus had short legs along the lines of Dreadnoughtus and some lognkosaurs, mainly because the fibula is so long and slender, and the femur is long too. There's no way to jam such a long fibula into a leg proportioned like Dreadnoughtus. Forget making the ankle joint history, the fibula would probably bust through the skin, down past the animal's heel! I can't such an animal walking...

So even though we don't have arm material for Argentinosaurus, and the leg material lacks a tibia and ankle and foot bones, the fact that we have a long femur and a long slender fibula already makes it pretty clear that this animal was more basal (and thus long-legged) than the longkosaurs. The tibia and hence the entire leg would have had to be pretty long. A lot longer proportionally than in a saltasaur, and even than in a lognkosaur. It's a fair bet that the arms were also more elongated than in lognkosaurs.
SameerPrehistorica's avatar
SameerPrehistoricaProfessional Digital Artist
Good job...Nice to see giant Brachiosaurs.I am sure they are your favorite Sauropod group.
Paleo-King's avatar
Paleo-KingProfessional Traditional Artist
Well I'd say both brachiosaurs and titanosaurs are my favorites... and most of the transitional forms in between, like the euhelopodids. :D
SameerPrehistorica's avatar
SameerPrehistoricaProfessional Digital Artist
For me also, some Brachiosaurids and Titanosaurids. Apatosaurus looks different from the Diplodocids and after the discovery of the Oklahoma Apatosaurus, i have added Apatosaurus to my favourites. This animal is like the right whale of the land animals. Short stockier neck, massive bulky body...
Paleo-King's avatar
Paleo-KingProfessional Traditional Artist
Yeah, Apatosaurus is an interesting critter. Much stranger than we often grew up learning. A. ajax is actually very different from A. louisae, and "A. excelsus" may once again be "Brontosaurus" based on re-analysis of its differences with the others. Technically though, Apatosaurus is a diplodocid. Just not a diplodocine.

The Oklahoma specimen is probably A. ajax, in which case the mounted skeleton in Sam Noble museum (which is largely speculative sculpture; the specimen is not complete) is probably wrong in a few spots, the neck should be longer and the shoulders higher. Apatosaurus ajax, despite being the type species, is actually rather different from most images we see of Apatosaurus, even modern ones, which all seem to be based on the stocky A. louisae with its shorter arms and shorter neck. A. ajax is actually rather unusual in being so long-armed and long-necked for an apatosaur (unless you compare it to Supersaurus!) and it's a good bit more slender than A. louisae.

Of course the fact that I've never seen an accurate mount of the Apatosaurus ajax type material in any museum really speaks to the fact that not much is known about the "original" Apatosaurus and a lot more work remains to be done. A. louisae, for reasons that are not really clear, has gotten a lot more attention and research. And as different as the two species are, I wouldn't be surprised if A. louisae turns out to be its own genus and gets kicked out of Apatosaurus altogether, as is now the case with Brontosaurus excelsus. Then we would seriously be looking at a whole different and long-ignored Apatosaurus that most people barely know.
CrashBandicoot2015's avatar
CrashBandicoot2015 Filmographer
he looks bigger than argentinasurus
Paleo-King's avatar
Paleo-KingProfessional Traditional Artist
Maybe taller, but Argentinosaurus was wide, had a longer torso, and was much more massive overall. Brachiosaurus were deep-bodied, but titanosaurs were FAT.
CrashBandicoot2015's avatar
CrashBandicoot2015 Filmographer
and everyone still thinking argentinasurus is the big one
Paleo-King's avatar
Paleo-KingProfessional Traditional Artist
Argentinosaurus is still much larger than Abydosaurus mass-wise. And it's longer overall. Abydosaurus MAY have been a bit taller. But that's just because of its proportions. Even the biggest brachiosaurs known do not match the biggest titanosaurs in weight and volume.
CrashBandicoot2015's avatar
CrashBandicoot2015 Filmographer
true
Kazuma27's avatar
Kazuma27Hobbyist General Artist
Didin't know the "famous" skull is a young one, interesting.
DiNoDrAwEr's avatar
DiNoDrAwErHobbyist Photographer
As I may have noticed your preference on macronarians, are you planning to do skeletals of the Haplocanthosaurus species? ;)
Paleo-King's avatar
Paleo-KingProfessional Traditional Artist
That's eventually planned. And also mamenchisaurs and even a few of the larger diplodocids.

Haplocanthosaurus is an interesting animal, since it's basically a late-surviving cetiosaur-like creature, which shows some traits of basal macronarians, with other ones resembling very primitive diplodocoids. It's been restored before, but probably with the shoulders too low.
Fragillimus335's avatar
Fragillimus335Hobbyist General Artist
I'd love to see your take on Supersaurus! :D
DiNoDrAwEr's avatar
DiNoDrAwErHobbyist Photographer
Would be really nice! :w00t:
Quite a bit of work on that I suggest... ;)
darklord86's avatar
Very nice!
Dontknowwhattodraw94's avatar
Dontknowwhattodraw94Hobbyist Traditional Artist
I always get astonished by those animals. You see that juvenile "little" dinosaur and you think 'd'awww that's small' and then you notice it's more than 6 metres tall... And then you notice a human just being more than dwarfed by the adult. Djeezus, why did those guys had to go extinct?
vasix's avatar
vasixHobbyist Digital Artist
Abydosaurus is much bigger than anybody expected it seems
Paleo-King's avatar
Paleo-KingProfessional Traditional Artist
Yes indeed. I hardly would have believed it myself if the second-largest specimen wasn't so obviously a subadult with NO fusion on the scapulacoracoid suture. That one still had some growing to do even at 75 ft. long, so you know the adults had to be even bigger - so the giant ribs of the adult aren't just a fluke of illustrator error in the quarry map, they are indeed that big (in fact they look even bigger on the map than shown here, but that may be due to crushing and flattening during fossilization).
anonymous's avatar
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