“Apatosaurus” minimus sacrum/ilia, right lateral view
June 27, 2012
From the collections of the American Museum of Natural History, I give you the sacrum and fused ilia of “Apatosaurus” minimus AMNH 675, as correctly identified by Steve P in a comment to the previous post:
As Steve P rightly pointed out, AMNH 675 was designated as Brontosaurus sp. by Osborn (1904), and made the type of Apatosaurus minimus by Mook (1917).
It’s been known for some time that whatever this is, it’s not Apatosaurus — see for example McIntosh (1990a:398), McIntosh (1990b:59) and Upchurch et al. (2004:298). But what actually is it? Well, at the moment, no-one knows. Matt and I now have a manuscript in prep that we hope will somewhat elucidate this question. More to come on this specimen, most likely.
References
McIntosh, John S. 1990a. Sauropoda. In The Dinosauria, pp. 345–401. Berkeley and Los Angeles: University of California Press.
McIntosh, John S. 1990b. Species Determination in Sauropod Dinosaurs with Tentative Suggestions for the Their Classification. In Dinosaur Systematics: Approaches and Perspectives, pp. 53–69. Cambridge: Cambridge University Press.
Mook, Charles C. 1917. Criteria for the determination of species in the Sauropoda, with description of a new species of Apatosaurus. Bulletin of the American Museum of Natural History 38:355-360.
Osborn, Henry F. 1904. Manus, sacrum, and caudals of Sauropoda. Bulletin of the American Museum of Natural History 20:181-190.
Sauropod Vertebra Picture of the Week 
June 27, 2012 at 9:01 pm
How big is this sacral, say, compared to your standard Apatosaurus?
June 27, 2012 at 9:34 pm
I’m actually not sure at the moment — obviously we’ll need to check measurements in the literature for the paper. My gut feeling is that it’s about the same size — maybe a bit shorter and a bit broader. It’s certainly not a lot smaller, so the choice of species name is puzzling.
June 28, 2012 at 6:55 am
Given the shape of the ilium and the config. of the sacral spines, I smell a Haplocanthosaurus connection here… not sure how strong the relationship is though.
June 28, 2012 at 7:10 am
Yes, the ilium shape in lateral view is less unlike Haplocanthosaurus than most other sauropods. But in dorsal/ventral and anterior/posterior views it’s very different; and the neural spines are about as different as they can be.
June 28, 2012 at 8:56 am
Eobrontosaurus?
June 28, 2012 at 9:20 am
It’s an intriguing possibility, Randy, but one that I don’t think we have any way to evaluate. The “Apatosaurus” yahnahpin material described by Filla and Redman (1994) has no sacrum, ilia or ischia, and overlaps with the “Apatosaurus” minimus material only in having a “partial pubis” which is not illustrated, nor even mentioned in the text beyond noting its existence — and which would scarcely be grounds for synonymy in isolation anyway.
I know that there are referred specimens of Eobrontosaurus but I’ve not seen descriptions of any of them (or any mention in the literature, come to that). Do you know of any?
June 29, 2012 at 6:28 am
Sigh….
June 30, 2012 at 9:30 am
[…] you’ll know from all the recent AMNH basement (and YPM gallery) photos, Matt and I spent last week in New York (with a day-trip to New Haven). […]
July 1, 2012 at 11:39 pm
[…] mentioned a few posts ago that Matt and I are working on a redescription of AMNH 675, a sauropod specimen referred by Mook […]