Just chillin’ with my homie FMNH PR 25107
September 5, 2023
That’s FMNH PR 25107, better known as a the holotype of Brachiosaurus altithorax — the biggest known dinosaur at the time of its description (Riggs 1903) and still for my money one of the most elegant, along with its buddy and one-time genus-mate Giraffatitan brancai.
I had a spare morning in Chicago two Tuesday ago, and Bill Simpson (collection manager of fossil vertebrates at the Field Museum) managed to fit it a collections visit for me at very short notice. I harvested some good science that morning — there’s a short Taylor and Wedel manuscript in review from that visit — but it would gave been churlish not to also take the opportunity to bathe in the sheer brachiosaurosity of it all.
Brachiosaurus altithorax holotype FMNH PR 25107 in collections at the Field Museum of Natural HIstory, Chicago. In the foreground, the femur. Behind it, at ground level, five of the seven presacral vertebrae and the sacrum; and on the shelf to the left, “Rib B”. On the top shelf, “Rib A”, the first two caudals and fragments of several more dorsal ribs. The remainder of the holotype (two more presacral vertebrae and the humerus) is on display in the public gallery.
I’m not too vain to take a selfie or two:
Me, with the 4th presacral vertebra of the Brachiosaurus altithorax holotype FMNH PR 25107 (i.e., the last-but-three dorsal vertebra), here seen in left posterolateral view.
Oh look, there I am again!
Me with all five of the most posterior presacral vertebrae, here seen in right posterolateral view.
“But tell me, Mike”, you ask: “Do they have a model skull based on that of Giraffatitan hidden away in collections?”
Why, yes! Yes, they do!
My ugly mug, again — this time with the even uglier mug of the model skull.
Yes, I have to admit it. Brachiosaurus taken as a whole may be as elegant as they come, but its skull taken alone is a minger. Forgive me. But it’s true.
Sauropod Vertebra Picture of the Week 
September 5, 2023 at 9:53 pm
ever since the sloth post I’ve been thinking the weirdly flattened femurs of giant ground sloths are weirdly similar to the weirdly flattened femurs of sauropods.
September 6, 2023 at 2:07 am
I visited the Field Museum last year and was disappointed not to be able to see the Brachiosaurus mount I remembered from my childhood. I hope they’ll restore it to its proper place some day; the titanosaur is fine and all, but it’s no Brachiosaurus.
It’s nice to see a little of the behind-the-scenes stuff that’s invisible to regular museum goers. I guess I always envisaged big fossils being wrapped in burlap and shoved into crates; pallets are a much more sensible solution. I assume they have a reach truck or a little forklift to move them around.
llewelly – Elephants have flat femurs too, it seems to be mandatory for animals in the preposterous size category. I’m sure there’s some engineering reason for it, probably something about “moment arm” or “modulus of bending”. Those are the sorts of things engineers like to say.
January 12, 2024 at 10:53 am
[…] I visited way back in 2005. He arranged to let me into the collection at 8:30am and then leave me free to look through the material, armed with a spreadsheet of what’s where. I really can’t emphasize enough how […]