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Friday, April 27, 2012
Yup, the OK Apatosaurus is freakin' huge!
The genesis of this post comes courtesy of a Matt Wedel post over at the excellent SV-POW! blog, where he was taking a look at the size of the partial Apatosaurus specimen preserved in Oklahoma, specimen OMNH 1670. Matt took a measuring tape to the OMNH specimen himself, and it measures up at a whopping 135 cm (for those of you who don't know the metric system, 135 centimeters is equal to one really big vertebra...).
But Matt really caught my attention when he stated:
...so the big Oklahoma Apatosaurus was probably in Supersaurus territory, mass-wise, and may have rivaled some of the big titanosaurs.
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| A younger me carving a pedal ungal. Look at that hair - what a hippy! |
Supersaurus is an animal near and dear to my heart - it's an animal I've literally shed blood over. Yes really. In addition to working with my coauthors on a description of the second specimen of Supersaurus and a reassessment of diplodocid phylogeny, we also had to produce a full mount of the animal under exceedingly tight time constraints. As with many small museums this meant we all had to pitch in, and that included learning how to sculpt missing bones. Near the very end of the project, while getting by on little more than 2 hours of sleep and coffee doses that would kill a small horse, I had a very small boo-boo with a carving knife (see photographic evidence at right). No stitches were necessary, and thankfully no sauropods where injured in the process.
The end result of our work was a mount that received top billing in a temporary exhibit in Japan in summer 2006. While the estimated length of 34 meters and mass estimate of 36-40 tonnes is smaller than some of the more sensational numbers that have been floated in popular books (and of course the internet), we suggested in our paper that many of those estimates were, shall we say... extravagant. Supersaurus appears to be close to the longest animal whose length can be reliably estimated (read: not counting Amphiceolias fragilimus), though it was lighter than the giant titanosaurs.
Given my personal stake here I wasn't about to take Matt's vicious maligning of Supersaurus on faith. But - and this is the darnedest thing about science - the facts are on his side. After scaling the fourth dorsal of Apatosaurus louisae up to the appropriate size, it turns out that the thing definitely is bulkier than Supersaurus. And if you try it with the other species of Apatosaurus (to whit: A. ajax and A. excelsus), it turns out just as bad - or worse in the case of A. ajax, who seems to have a proportionately shorter D4, which in turn leads to a larger animal when it's scaled to 135 cm.
Of course Supersaurus still looks to be longer by a fair amount, in large part due to the highly elongate neck. But when it comes to moving the dial on a scale, it's clear that Apatosaurus is just more sauropod than Supersaurus. Oh well Jimbo, we'll always have Japan...
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Ha! Nice post. Sorry to, um, malign your baby. No offense intended! :-)
ReplyDeleteI have a second post on OMNH 1670 coming up, and probably a few more on the giant OK Apatosaurus down the line. Do you mind if I borrow a small version of your Apatosaurus/Supersaurus comparison for my next post--with attribution of course--and point people to this post for the full discussion?
No, please go ahead and use my work to continue to wallop somewhat-less-Supersaurus. ;)
ReplyDeleteThis kind of post helps while I'm working on describing KU's brachiosaurs out of Wyoming. Though when seeing your photo on here, I'm wondering where Silent Bob is hiding...
ReplyDeleteHow's it look in profile? Is one much thicker than the other?
ReplyDeleteBeautiful reconstruction! How tall at the shoulder is Jumbo in the Japanese museum?
ReplyDeleteI seem to recall Jim Kirkland showing a picture of a giant Apatosaurus vert years ago at SVP: I wonder if it is this one.
ReplyDeleteThanks everyone!
ReplyDelete@David - while several giganntic ribs are preserved for Supersaurus, they were squished flat, so I can't say for certain, but it looks like they would be similarly thick across the abdomen in top view (both being thinner than titanosaurs).
@Tom - It certainly could be, but there's also a large apatosaur pelvis (and presumably other remains) in Grand Junction. For interested observers there's also a small museum in Utah that digs on private land that we were invited to visit (thinking it might be Supersaurus) but it also appears to be apatosaur (but in a similar size range). Alas, only the OK specimen resides in the annals of a journal to this point.
ReplyDeleteThank you for this fascinating post Mr. Hartmen,
ReplyDeleteThe Apatosaur specimen OMNH 1670, along with the apatosaur pelvis and remains in Grand Junction should make for an interesting research project. I envy the paleontologist or student that gets to study this.
After viewing the mounted Apatosaurus louisae at the Carnegie, and reading your post, I'm wondering if Apatosaurus could possibly be considered among the most massive of sauropods? Reconstructions of the animal e.g. (Wedels post SVP-POW on the sideshow apatosaurus model), show it as being very bulky when compared to other sauropods. Either way, Apatosaurus looks like it may well turn out a big contender as sauropods go. Too bad "Brontosaurus" is no loner the valid name for a sauropod as massive as this.
IIRC, the OMNH apatosaur was identified as A. ajax, while you used A. excelsus in the scale drawing. Has it changes species since the exhibit was put together?
ReplyDeleteOh, wait, that's A. louisae in the drawing. Question still applies though.
ReplyDelete@Matt - I think the large titanosaurs will still outclass the biggest apatosaurs for mass, but it may be closer than once thought.
ReplyDelete@Jaimie - My A. ajax skeletal is a subadult, and as such I'm not fully confident of the proportions of the species at full size. Also, there's still a lot of fussing left to do with diplodocid species-level taxonomy, so I'm not sweating it yet. When I can improve the comparison with better data I will though, promise!
Can anyone tell me why so many restorations of dinosaurs assume that the legs and forelimbs are practically fleshless? Scott Hartman's beautiful work strikes me as a prime example of this trend. Both the Supersaurus and Apatosaurus legs in the outlined skeletals shown here are so lacking in musculature as to be almost impossible. It also seems to me that taking this point of view of fleshing out the animals skews the data badly on their mass AND their proportions. Frankly, I do not give a rodent's tokus how much they weighed, the lighter, the better for the beasts in question, actually.
ReplyDeleteI have seen too many dinosaur documentaries in which dinosaurs are often fleshed out in ways that would have crushed the bones. HOW can a Tyrannosaurus leg when alive be thinner than the bones? Is an assumption being made that the bones swelled in diameter after death? Where is the cartilage? Is it also thought that because we do not see the flesh, fat, skin, blood vessels and skin on the fossil bones that they must not have existed?
If these factors are so often ignored, how can we trust ANY of the estimates given on any position pertaining to the matter of linear size and the mass of any of the animals being talked about?
Any replies can be sent to dynokiller@yahoo.com.