September 22, 2015
The process of reassembling my cat skull continues. I now have the sphenoid and both nasals now back in place, and the time has come for the now-traditional multiview. (Previous examples: pig skull, wallaby skull, sheep skull.
Click through for seriously high resolution (9602 × 7642).
And here it is on a black background:
As though you need to be told: the top row shows the dorsal view, the middle row (from left to right) shows posterior, right lateral and anterior views, and the bottom row shows the ventral view.
September 17, 2015
Regular readers will remember that I recently fished my cat skull out of the tub where invertebrates had been hard at work defleshing it, and put it to soak — first in soapy water, then in clean water, and finally in dilute hydrogen peroxide. It was in a pretty terrible state, having either been smashed by a car, or damaged by my rather unsophisticated process of removing the head from the torso. Here’s a reminder:
After bleaching in H2O2, the skull parts looked much better, but were still very delicate. Here is the main portion of the cranium, missing the braincase and the right upper jaw, upside down, in right posteroventral view.
Putting it back together was difficult. I am using regular water-soluble wood glue, largely so that if I make a mistake I can just soak the wrongly-joined bits apart and try again.
I started by gluing the braincase (at the top of the plate in the first picture) onto the back of the main cranium piece. Unfortunately, as you’ll see below, I wasn’t able to get a very clean join — I can only assume that one or other part was slightly distorted by whatever force broke the skull apart. Still, having done that, I had a better platform to reattach the right upper jaw (lower left of the plate). I was then able to reattach the broken-off part of the right zygomatic arch (at about 4 o’clock on the plate, just to the right of the lower of the two dentaries, and below a vertebra). It didn’t fit quite right, but what can you do? FInally, I was able to reattach another small piece — at 6:30 pm on the plate — which I think is part of the left auditory bulla.
That gave me a workable cranium (though I have some bits left over — see below.) It was time to repair the right dentary. Its articular cylinder (not really a condyle, despite its name) had somehow got blasted off, as had its retroarticular process: it was quite satisfying to figure out how those Shards Of Mediocrity fitted onto the main part of the dentary.
With that done, I had to glue together the two dentaries. That’s hard to do: it’s awkward to brace them in position for the glue to set, and difficult to get the angle between the two bones correct so that the two articular cylinders both sit neatle in their receptacles in the cranium. Here’s the solution I came up with:
I rested the cranium upside down, covered the jaw with some thin, pliant plastic (actually a sandwich bag) and used the cranium itself as a perfectly proportioned brace to hold the dentaries in place. Then I was able to glue them more or less correctly, and to reinforce the joint with more glue once the first lot had set.
I’ve still not got it quite right — the mandibular symphysis is wonky — but I think it will do. And if I change my mind, I can always soak the mandible apart and try again.
(As a matter of fact, I’d already done that once, having initially glued the dentaries together at the wrong angle, so that the assembled mandible was too narrow, and wouldn’t articulate properly with the cranium.)
So now I have a pretty good mandible and cranium, as well as the first five cervical vertebrae (all but one of the postzygs of C5, which was lost in the head-removal process.) Here is the whole thing, put together, in dorsal view:
(You can see where the left zygomatic arch is damaged: the bones are not articulating correctly, as they do on the right.)
And here is the same assembly in left dorsolateral view:
And finally, the skull in anterodorsal view:
Note that the left canine is truncated. I am completely certain that this, at least, is not my doing, and must be damage that was done in life. Note, too, how the mandible is visibly wonky from this angle. Hmm. Maybe I will reset it again.
At the end of this process, I have a pretty nice cat skull. Unfortunately, I have seven shards left over, none of them more than about fifteen millimeters long. Here they are:
I’d welcome any help in figuring out what these bits are, and where on the skull they should be reattached. I don’t want to just throw them away. Click through for much higher resolution to get a better idea of what’s what. The top right piece is such a weird shape that someone must know what it is. The two peices at bottom right seem to be pairs, but I don’t know what they are a pair of. The rest? No idea.
I leave you with the dorsal view again, but this time in glorious 3D for those of you who have been wise enough to get some red-cyan 3D glasses. (Seriously folks, they’re like fifty cents a pair. Just get some. You won’t regret it.)
Some time soon: those first five cervicals in more detail.
September 11, 2015
Just under a year ago, the children across the road, who know I’m interested in comparative anatomy, told me that they’d found a dead cat by the side of the road, and asked whether I wanted it. Silly question, of course I did!
I’ve learned from bitter experience that prepping the whole skeleton out of an animal is a very time-consuming process — so time-consuming that I usually just don’t get around to it. This time, I thought I’d just do the skull. So I removed the head (not a pleasant process) and discarded the body.
I did the usual sequence of simmerings with the head, peeling off the skin and fur, then removing muscle, till I was down to just bone, gristle, and the hard-to-remove bits of soft tissue that always adhere in one place or another. At that point, I left the bones in a plastic tub in the woodshed, with a couple of holes in the lid so that invertebrates could get in and deal with the remaining gloop.
Yesterday I had a look (and a smell), and it seems all the soft-tissue is gone, thanks to the hard work of the tiny collaborators who never make it into the acknowledgements. So I soaked the skull pieces in soapy water for a day. Then today, I rinsed them off and left them to soak in pure water for a few hours. Finally, I changed the water, and added some H2O2 to degrease the bones. They are now foaming away merrily. Tomorrow I’ll take them out, rinse them off one more time, dry them, and see what state they’re in.
Here’s how they look today, after rinsing:
And here is a closeup of a mandible (slightly foreshortened):
“But Mike”, you ask, “Why is it in so many pieces?”
I actually don’t know. As I was taking the head apart, it seemed to be whole, but as it got down to the raw bone, it was apparent that the skull was very badly damaged. In the picture above, the main part of the cranium is upside down, half way down the left hand side. Below it is the rest of the cranium, the left side of the upper jaw. Above that is the back of the cranium, most of the braincase. The whole thing just came apart into three pieces — and not along sutures. This is breakage.
I’m not sure how it happened. At first, I thought it must be how the cat died — maybe struck a glancing blow by a car. But I increasingly wonder whether I stupidly did this myself in the process of removing the head from the torso. (I did not use a scalpel.)
Anyway, we’ll see how well the pieces can be reassembled once they have dried out. I’m optimised that I can still wind up with a pretty good cat skull.
August 19, 2015
As stinkin’ ornithischians go, Tenontosaurus is near and dear to my heart. For some reason beyond the ken of mortals, the Antlers Formation of southeast Oklahoma has yielded only a small handful of Acrocanthosaurus (Stovall and Langston 1950; Currie and Carpenter 2000), one partial Deinonychus skeleton and a few dozen shed teeth (Brinkman et al. 1998), the single, lonely, woefully incomplete holotype specimen of Sauroposeidon (Wedel et al. 2000a, b) – and roughly five flarkjillion skeletons of Tenontosaurus. I know a lot of those skeletons intimately: between 1994 and 2001, I went on about two dozen OMNH digs to pull them out of the ground, and I worked on a couple as a volunteer preparator.
I was off to Berkeley in 2001, so I missed the fun when another crew got the best-ever Tonto specimen, OMNH 58340. Except for the back half of the tail, which had eroded away, almost every bit of the skeleton was preserved in perfect articulation, even the hyoid apparatus, terminal phalanges, proatlas, and atlas cervical ribs. The skull was a bit disarticulated – half of the rostrum had floated out of position, and the stapes and palpebrals were missing – but it’s still the nicest Tonto skull ever found, and one of the best-preserved fossils to ever come out of the Antlers Formation.
Now that skull has been very thoroughly described by Andrew Thomas. Andrew wrote it up for his MS thesis under my first mentor, Rich Cifelli, and it was published last month in Palaeontologica Electronica (Thomas 2015). I had dinner with Andrew and his family when I visited the OMNH in the spring of 2014, and he showed me a down-scaled translucent 3D print of the left half of OMNH 58340. I learned more about ornithischian skulls playing with that thing over dinner than I had in the previous two decades of (admittedly quarter-assed) study.
So there’s me, playing with a down-scaled 3D print of a Tonto skull. Why am I telling you about this? Because if you want to print your own, you can – digital models of the complete cranium, and all of the individual elements, are available as STL files published along with the paper. Getting to the models takes some doing – they’re in a ZIP file linked from the paper’s Appendix 4, which you can access directly here.
Thomas (2015) has a lot more than just cool 3D models – there’s a lot of descriptive goodness, including the cranial endocast, cranial nerves, inner ear labyrinth, and hyoids; a whopping 62 figures, most in full color; and a phylogenetic analysis that incorporates the new morphological data on Tenontosaurus. No revelations there – despite all the nice specimens, Tonto remains an enigma from the murky realm between basal ornithopods and Iguanodontia. But if Oklahoma’s most abundant dinosaur is a bit of a phylogenetic mystery, it’s also becoming a paleobiologic gold mine, thanks in large part to the bone histology studies of Sarah Werning and colleagues (Lee and Werning 2008; Werning 2012 – also see Horner et al. 2009 on histology of Tenontosaurus from the Cloverly Formation of Montana). With the publication of this paper, Andrew Thomas is now part of the “Tenontaissance”. Congratulations, Andrew, and well done!
Now if we could just get some more Sauroposeidon…
- Brinkman, D. L.; Cifelli, R. L.; & Czaplewski , N. J. (1998). First occurrence of Deinonychus antirrhopus (Dinosauria: Theropoda) from the Antlers Formation (Lower Cretaceous: Aptian–Albian) of Oklahoma. Oklahoma Geological Survey Bulletin 146: 1–27.
- Currie, P. J., & Carpenter, K. (2000). A new specimen of Acrocanthosaurus atokensis (Theropoda, Dinosauria) from the Lower Cretaceous Antlers Formation (Lower Cretaceous, Aptian) of Oklahoma, USA. Geodiversitas, 22(2), 207-246.
- Horner JR, de Ricqlès A, Padian K, Scheetz RD (2009) Comparative long bone histology and growth of the “hypsilophodontid” dinosaurs Orodromeus makelai, Dryosaurus altus, and Tenontosaurus tilletti (Ornithischia: Euornithopoda). Journal of Vertebrate Paleontology 29: 734–747.
- Lee, A. H., & Werning, S. (2008). Sexual maturity in growing dinosaurs does not fit reptilian growth models. Proceedings of the National Academy of Sciences, 105(2), 582-587.
- Stovall, J. W., & Langston, W. (1950). Acrocanthosaurus atokensis, a new genus and species of Lower Cretaceous Theropoda from Oklahoma. American Midland Naturalist, 43(3), 696-728.
- Thomas, D. Andrew. 2015. The cranial anatomy of Tenontosaurus tilletti Ostrom, 1970 (Dinosauria, Ornithopoda). Palaeontologia Electronica 18.2.37A: 1-99.
- Wedel, M.J., Cifelli, R.L., and Sanders, R.K. 2000a. Sauroposeidon proteles, a new sauropod from the Early Cretaceous of Oklahoma. Journal of Vertebrate Paleontology 20: 109-114.
- Wedel, M.J., Cifelli, R.L., and Sanders, R.K. 2000b. Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. Acta Palaeontologica Polonica 45:343-388.
- Werning, S. (2012). The ontogenetic osteohistology of Tenontosaurus tilletti. PLoS ONE 7(3): e33539. doi:10.1371/journal.pone.0033539
July 8, 2015
Now that, faithful readers, is a monument to evolution and its endless forms most beautiful. I’m talking about the wall of ceratopsian skulls at NHMU, of course, not the back of Brian Engh’s head (bottom center).
If you don’t know them all on sight (yet!), here’s a cheat sheet. I goofed on a couple myself: before I looked at the sheet I figured Coahuilaceratops as Pentaceratops and mistook Kosmoceratops for Vagaceratops. Still, 12 out of 14 isn’t bad for a minor-league ceratopsian scholar such as yours truly.
Here’s the chasmosaurine-centric view from lower right.
And the centrosaurine-centric view from distant left.
The world needs more things like this. Good on ya, NHMU.
For other NHMU posts, see:
June 16, 2015
We stopped off at the Peggy’s Cove lighthouse on the way, and spotted a vertebrate, which I am pleased to present:
It’s a whale skull, but I have no idea what kind. Can anyone help out?
So much for vertebrates — it was really all about the inverts. Here are six of them:
I have a 2lb lobster here; my colleague Jakub went for two 1lb lobsters, as did Jason and Wolfram (not pictured). That’s Wolfram’s lobster closest to the camera, giving a better impression of just what awesome beasts these were.
Peggy’s Cove: recommended. For vertebrates and inverts.
(Thanks to Wolfram Schneider for these photos.)
May 23, 2015
A couple of months ago, Darren (the silent partner in the SV-POW! organisation) tweeted this photo …
… describing it as “Skull of the Morrison Formation Brachiosaurus at Denver Museum of Nature & Science”.
As Darren knows well (but didn’t have have space to explain in the tweet), it’s not quite as simple as that. What follows is adapted from Taylor 2009:789.
In 1883, a large sauropod skull (81 cm in length) was found in Felch Quarry 1, Garden Park, Colorado. It was shipped to O. C. Marsh in Yale that year and an illustration of the skull was used in his second attempt at reconstructing the skeleton of Brontosaurus (Marsh, 1891: plate 16).
And here’s that skull in close-up:
This is often described as a “Camarasaurus-type” skull, but it’s not, really. It’s too long and low, and not stupid and ugly enough, to be Camarasaurus.
As we described in a previous post, this skull was also apparently the inspiration for the horrible, horrible sculpted skull that was originally used on the mounted Brontosaurus. (And let me reiterate my praise of the Yale museum for displaying this important historic object in their gallery instead of hiding it away.)
Anyway, the Felch Quarry skull was subsequently transferred to the National Museum of Natural History, where it was accessioned as USNM 5730. McIntosh and Berman (1975:195-198) recognized that whatever the skull was, it wasn’t Brontosaurus, but chickened out a bit by describing it as being “of the general Camarasaurus type” (p. 196). But McIntosh subsequently identified the skull tentatively as Brachiosaurus (Carpenter and Tidwell, 1998:70) and it was later described by Carpenter and Tidwell (1998), who considered it intermediate between the skulls of Camarasaurus and Giraffatitan, and referred it to Brachiosaurus sp.
The skull may be that of Brachiosaurus altithorax, but this is currently impossible to test due to the lack of comparable parts. Near this skull was a 99 cm cervical vertebra, probably of Brachiosaurus, but this was destroyed during attempts to collect it (McIntosh and Berman, 1975:196). Shame there are no photos.
- Carpenter, Kenneth, and Virginia Tidwell. 1998. Preliminary description of a Brachiosaurus skull from Felch Quarry 1, Garden Park, Colorado. Modern Geology 23:69-84.
- Marsh, Othniel Charles. 1891. Restoration of Triceratops. American Journal of Science, Series 3, 41:339-342.
- McIntosh, John S., and David S. Berman. 1975. Description of the palate and lower jaw of the sauropod dinosaur Diplodocus (Reptilia: Saurischia) with remarks on the nature of the skull of Apatosaurus. Journal of Paleontology 49:187-199.
- Taylor, Michael P. 2009. A re-evaluation of Brachiosaurus altithorax Riggs 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai (Janensch 1914). Journal of Vertebrate Paleontology 29(3):787-806.