August 28, 2014
I’m scrambling to get everything done before I leave for England and SVPCA this weekend, so no time for a substantive post. Instead, some goodies from old papers I’ve been reading. Explanations will have to come in the comments, if at all.
For more noodling about nerves, please see:
- The world’s longest cells? Speculations on the nervous systems of sauropods
- Oblivious sauropods being eaten
- Butler, A.B., and Hodos, W. 1996. Comparative Vertebrate Neuroanatomy: Evolution and Adaptation. 514 pp. Wiley–Liss, New York.
- Nieuwenhuys, R. (1964). Comparative anatomy of the spinal cord. Progress in Brain Research, 11, 1-57.
- Streeter, G. L. (1904). The structure of the spinal cord of the ostrich. American Journal of Anatomy, 3(1), 1-27.
- Janensch, Werner. 1950. Die Wirbelsaule von Brachiosaurus brancai. Palaeontographica (Suppl. 7) 3: 27-93.
- Wedel, M.J., and Sanders, R.K. 2002. Osteological correlates of cervical musculature in Aves and Sauropoda (Dinosauria: Saurischia), with comments on the cervical ribs of Apatosaurus. PaleoBios 22(3):1-6.
- Wedel, M.J., Cifelli, R.L., and Sanders, R.K. 2000b. Osteology, paleobiology, and relationships of the sauropod dinosaurSauroposeidon. Acta Palaeontologica Polonica 45(4): 343-388.
That last one really hurts. Here’s the original image, which should have gone in the paper with the interpretive trace next to it rather than on top of it:
Papers referenced in these slides:
- Taylor, M.P., and Wedel, M.J. 2013b. The effect of intervertebral cartilage on neutral posture and range of motion in the necks of sauropod dinosaurs. PLOS ONE 8(10): e78214. 17 pages. doi:10.1371/journal.pone.0078214
- Wedel, M.J. 2007a. What pneumaticity tells us about ‘prosauropods’, and vice versa. Special Papers in Palaeontology 77:207-222.
- Wedel, Mathew J., Richard L. Cifelli and R. Kent Sanders. 2000b. Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. Acta Palaeontologica Polonica 45(4): 343-388.
January 10, 2014
I made these back in the day. The idea was that you could print them out and have them along while dissecting bird necks, so you could draw on the muscles.
It’s basically one drawing of an ostrich vertebra, morphed in GIMP and stacked to simulate articulation. All of the ones in this post show the vertebrae in left lateral view. If you need right views, flip ’em in GIMP or heck, I think even Windows Explorer will do that for you. The one above has dorsal views in the top row, lateral view in the middle row, and ventral views in the bottom row.
Here’s a sheet with two rows in lateral view, the idea being that you draw on the more superficial multi-segment muscles on one row, and the deeper single- or two-segment muscles on the other row.
A version with 12 vertebrae, so you can map out the often complicated patterns of origins and insertions in the really long muscles. How complicated? Well, check out this rhea neck with the M. longus colli dorsalis and M. longus colli ventralis fanned out.
That’s all. Have fun!
April 10, 2013
This is a caudal vertebra from the middle of the tail of an ostrich, LACM Bj342:
The middle row shows it in anterior, left lateral and posterior views; above and below the anterior view are the dorsal and ventral views. It’s about 5 cm across the transverse processes. (This figure is from a manuscript that Matt and I will submit to a journal probably within 24 hours.)
In compositing the different views, I had a heck of a time recognising what was what. The dorsal view looks so much more like what we’d expect a ventral view to look like — indeed, the two are more similar for this vertebra than for any other I’ve seen.
How about those big pnuematic foramina right at the top of the bone? At first, Matt and I thought we’d never seen anything like that before. But then we realised that we sort of had — in a cervical vertebra of Apatosaurus which appears as part one of Taylor and Wedel (2013: figure 9).
This is Apatosaurus sp. OMNH 01341 in right posterodorsolateral view. “las” marks a ligament attachment site — a big, baseball-sized rugose lump — and right next to it is a pneumatic foramen, marked “pfo”.
Just like this, the ostrich caudal is a saurischian vertebra with a bifid neural spine, and with pneumatic foramina within the intermetapophyseal cleft.
June 12, 2012
More from my flying visit to the Harvard Museum of Natural History. I found this exhibition of bird eggs very striking. In particular, it was shocking how much bigger the elephant-bird egg is than that of the ostrich.
From smallest to largest, the eggs are those of:
- Ruby-throated Hummingbird Archilochus colubris
- Common Redpoll Carduelis flammea
- House Finch Carpodacus mexicanus
- Eastern Screech Own Megascops asio
- Thick-billed Parrot Rhynchopsitta pachyrhyncho
- Red-necked Grebe Podiceps grisegeno
- Magnificent Frigatebird Fregata magnificens
- Red-tailed Hawk Buteo jamaicensis
- Cackling Goose Branta hutchinsii
- Bald Eagle Haliaeetus leucocephalus
- Tundra Swan Cygnus columbianus
- Wandering Albatross Diomedeo exulans
- Ostrich Struthio camelus
- Elephant bird Aepyornis sp.
As always, click through for full resolution.
March 14, 2012
Another picture from the recent ostrich dissection (click for full-size, unlabeled version). Last time we were in the middle of the neck, looking from anterior to posterior. This shot is from closer to the base of the neck, looking from posterior to anterior. A lot of the stuff is the same: the ragged cut from the saw at the meat processing plant where the ostrich was cut up; the spinal cord with the supramedullary airways above it in the neural canal; and the large interspinous ligament with diverticula on either side. We’ll have reason to refer back to some of those things in the not-too-distant future, but right now I want to draw your attention to something else: the tendons of the paired longus colli dorsalis muscles toward the top of the photo.
Here’s a modified version of Wedel and Sander (2002: fig. 2) with the course of the longus colli dorsalis highlighted in red (anterior is to the left). It is a curious aspect of bird necks that the large dorsal muscles do not insert on the neural spines but on the epipophyses (or dorsal tori or dorsal tubercles) above the postzygs. A naive approach based on beam theory would suggest that inserting on the neural spines would give those muscles more leverage, but necks are tricky and often defy such a priori predictions.
Instead of inserting on the neural spines, the longus colli dorsalis muscles originate from them, especially in the posterior part of the neck, and that’s what the photo at the top shows. From the reader’s point of view, the big interspinous ligament runs forward to attach to the posterior side of the neural spine (not visible because it’s buried in gloop, but it’s about a third of the way down from the top). The longus colli dorsalis tendons are running forward from the anterior side of the neural spine.
Here’s the same thing again, also in an ostrich, but in an MRI this time (and with anterior to the right; Wedel et al. 2000: fig. 20). The dark streaks running forward from the neural spines are those longus colli dorsalis tendons. The interspinous ligament also shows up nicely as a series of white bands connecting adjacent neural spines.
- Wedel, M.J. 2005. Postcranial skeletal pneumaticity in sauropods and its implications for mass estimates; pp. 201-228 in Wilson, J.A., and Curry-Rogers, K. (eds.), The Sauropods: Evolution and Paleobiology. University of California Press, Berkeley.
- Wedel, M.J., R.L. Cifelli and R.K. Sanders. 2000. Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. Acta Palaeontologica Polonica 45(4): 343-388.