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
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.
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
: 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).