Shoebills lie tell the truth (and it’s disgusting)
January 27, 2020
Heinrich Mallison sent me this amazing photo, which he found unattributed on Facebook:
Infuriatingly, I’ve not been able to track down an original source for this: searching for the text just finds a bunch of reposts on meme sites, and Google’s reverse image search just reports a bunch of hits on Reddit:
The line-drawing shows some scientific understanding of bird skeletons, so I imagine someone put real thought into this and is unhappy that the image is propagating uncredited. If that person reads this, please leave a comment: I’d love to credit it properly.
Anyway … what’s going on here?
Birds (like all vertebrates) have two tubes running down the ventral aspect of the neck (i.e. below the vertebrae): the trachea, for breathing, and the oesophagus, for swallowing. But these both open into the back of the mouth and are not piped up past it. I’ve not dissected enough bird heads to show this clearly, but when I was taking Veronica apart the trachea was pretty visibly ending in the mouth cavity, not plumbed up past the mouth into the nasal space:
So yes, I think it’s true: shoebills can bulge their spines out of their mouths.
Why? My best guess that there’s just nowhere else for the spine to go when the neck is retracted. There’s a big empty space in the mouth, why let it go to waste?
Proof that penguins evolved from bears
March 11, 2019
The Atterholt and Wedel (2018) SVPCA abstract and talk are now available on PeerJ Preprints
September 14, 2018
Here’s the story of my fascination with supramedullary airways over the last 20 years, and how Jessie Atterholt and I ended up working on them together, culminating with her talk at SVPCA last week. (Just here for the preprint link? Here you go.)
Müller (1908: fig. 12). Upper respiratory tract, trachea, and lungs in pink, air sacs and diverticula in blue. DSPM = diverticulum supramedullare.
Way back when I was working on my Master’s thesis at the University of Oklahoma and getting into pneumaticity for the first time, Kent Sanders found Müller (1908) and gave me a photocopy. This would have been the spring or summer of 1998, because we used some of Müller’s illustrations in our poster for SVP that year (Wedel and Sanders 1998). Müller’s description of pneumatic diverticula in the pigeon formed part of my intellectual bedrock, and I’ve referenced it a lot in my pneumaticity papers (complete list here).
One of the systems that Müller described is the diverticulum supramedullare, a.k.a. supramedullary diverticula, or, informally, supramedullary airways (SMAs). Traditionally these are defined as pneumatic diverticula that enter the neural canal and lie dorsal (supra) to the spinal cord (medulla), although O’Connor (2006) noted that in some cases the diverticula could completely envelop the spinal cord in a tube of air. I yapped about SMAs a bit in this post, and they’re flagged in almost every ostrich CT or dissection photo I’ve ever published, here on the blog or in a paper.
CT sections of a Giraffatitan cervical, with connections between the neural canal and pneumatic chambers in the spine highlighted in blue. Modified from Schwarz & Fritsch (2004: fig. 4).
Fast forward to 2006, when Daniela Schwarz and Guido Fritsch documented pneumatic foramina in the roof of the neural canal in cervical vertebrae of Giraffatitan. As far as I know, this was the first published demonstration of SMAs in a non-bird, or in any extinct animal. Lemme repeat that: Daniela Schwarz found these first!
OMNH 60718: too ugly for radio. This is an unfused neural arch in ventral view. Anterior is to the left. Neurocentral joint surfaces are drawn over with ladders; pneumatic foramina lie between them.
Shortly thereafter I independently found evidence of SMAs in a sauropod, in the form of multiple pneumatic foramina in the roof of the neural canal in an unfused neural arch of a basal titanosauriform (probably a brachiosaurid) from the Cloverly Formation of Montana. It’s a pretty roadkilled specimen and I was busy with other things so I didn’t get around to writing it up, but I didn’t forget about it, either (I rarely forget about stuff like this).
Then in 2013 I went to the Perot Museum in Dallas to see the giant Alamosaurus cervical series, and I also visited the off-site research facility where juvenile Alamosaurus from Big Bend is housed. When Ron Tykoski let me into the collections room, I was literally walking through the door for the first time when I exclaimed, “Holy crap!” I had spotted an unfused neural arch of a juvenile Alamosaurus on a shelf across the room, with complex pneumatic sculpting all over the roof of the neural canal.
Title slide for the 2014 SVPCA presentation.
The Big Bend and Cloverly specimens were the basis for my talk on SMAs at SVPCA in 2014, coauthored with Anthony Fiorillo, Des Maxwell, and Ron Tykoski. As prep for that talk, I visited the ornithology collections at the Natural History Museum of Los Angeles County, photographed a lot of bird vertebrae with foramina inside their neural canals, and shot this pelican video. That was four years ago – why no paper yet? It’s because I wanted one more piece of smoking-gun evidence: a CT scan of a bird that would show a direct communication between the SMAs and the air spaces inside a vertebra, through one or more foramina in the roof, wall, or floor of the neural canal.
A spectrum of pneumatic traces in the neural canals of birds, including complexes of large or small foramina, isolated foramina, and sculpting without foramina.
In 2017, Jessie Atterholt taught in our summer anatomy course at WesternU as an adjunct (her full-time employment was at the Webb Schools in Claremont, home of the Alf Museum). Jessie and I had been acquainted for a few years, but we’d never had the opportunity to really talk science. As we chatted between dissections, I learned that she had a huge warchest of CT scans of whole birds from her dissertation work at Berkeley (we’d missed each other by a few years). My antennae twitched: one nice thing about SMAs is that, being bounded by bone, they can’t collapse after death, unlike more peripheral diverticula. And air is jet black on CT scans, so SMAs are easy to spot even on comparatively low-res scans. All you need is one or two black pixels. I proposed a collaboration: we could use her CT scans to survey the presence and distribution of SMAs in as many birds as possible.
Vertebral diverticula in two sagittally-exploded cervical vertebrae of a turkey. Anterior is to the left, #5 is the SMA. Cover (1953: fig. 2). Yes, I know this is gross – if anyone has a cleaner scan, I’m interested.
You might think that such a survey would have been done ages ago, but it’s not the case. A few authors have mentioned supramedullary airways, and O’Connor (2006) gave a good description of some of the variation in SMAs in extant birds as a whole. But the only detailed accounts to illustrate the morphology and extent of the SMAs in a single species are Müller (1908) on the common pigeon and Cover (1953) on the domestic turkey. I’d seen what I suspected were traces of SMAs in the vertebrae of many, mostly large-bodied birds, and I’d seen them in CTs of ostriches and hummingbirds, and in ostriches and turkeys in dissection. But Jessie was offering the chance to see both the SMAs and their osteological traces in dozens of species from across the avian tree.
SMAs in a micro-CT of a female Anna’s hummingbird, Calypte anna. Scale bars are in mm.
Real life intervened: we were both so busy teaching last fall that we didn’t get rolling until just before the holidays. But the project gradually built up steam over the course of 2018. One story that will require more unpacking later: everything I’ve written on this blog about neural canals, Haplocanthosaurus, or CT scanning in 2018 is something serendipitously spun out of the SMA survey with Jessie. Expect a lot more Atterholt and Wedel joints in the near future – and one Atterholt et al. (minus Wedel) even sooner, that is going to be big news. Watch this space.
It didn’t hurt that in the meantime Jessie got a tenure-track job teaching human anatomy at WesternU, to run the same course she’d taught in as an adjunct last year, and started here at the beginning of June. By that time we had an abstract on our findings ready to go for this year’s SVP meeting. Alas, it was not to be: we were out in the field this summer when we learned that our abstract had been rejected. (I have no idea why; we’ve increased the taxonomic sampling of SMAs in extant birds by a factor of six or so, most of our important findings are in the abstract, and we mentioned the relevance to fossils. But whatever.)
We were bummed for a day, and then Jessie decided that she’d submit the abstract to SVPCA, only slightly chopped for length, and go to Manchester to present if it was accepted – which it was. Unfortunately I’d already made other plans for the fall, so I missed the fun. Fortunately the SVPCA talks were livestreamed, so last Friday at 1:30 in the morning I got to watch Jessie give the talk. I wish the talks had been recorded, because she knocked it out of the park.
Title slide for the 2018 SVPCA presentation.
And now everything we’re in a position to share is freely available at PeerJ. The SVPCA abstract is up as a PeerJ preprint (Atterholt and Wedel 2018), the longer, rejected SVP abstract is up as a supplementary file (because it has a crucial paragraph of results we had to cut to make the length requirement for SVPCA, and because why not), and our slideshow is up now, too. I say ‘our’ slideshow but it’s really Jessie’s – she built it and delivered it with minimal input from me, while I held down the sauropod side of our expanding empire of neural canal projects. She has the paper mostly written, too.
Oh, and we did get the smoking-gun images I wanted, of SMAs communicating with pneumatic spaces in the vertebrae via foramina in the neural canal. Often these foramina go up into the neural arch and spine, but in some cases – notably in pelicans and the occasional ratite – they go down into the centrum. So I now have no excuse for not getting back to the sauropod SMA paper (among many other things).
We’re making this all available because not only are we not afraid of getting scooped, we’re trying to get the word out. SMAs are phylogenetically widespread in birds and we know they were present in sauropods as well, so we should see some evidence of them in theropods and pterosaurs (because reasons). I made such a nuisance of myself at the recent Flugsaurier meeting, talking to everyone who would listen about SMAs, that Dave Hone went and found some pneumatic foramina in the neural canals of Pteranodon vertebrae during the conference – I suspect just to shut me up. That’ll be some kind of Hone-Atterholt-Wedel-and-some-others joint before long, too.
Anyway, point is, SMAs are cool, and you now have everything you need to go find them in more critters. Jessie and I are happy to collaborate if you’re interested – if nothing else, we have the background, lit review, and phylogenetic sampling down tight – but we don’t own SMAs, and we’ll be nothing but thrilled when your own reports start rolling in. Unexplored anatomical territory beckons, people. Let’s do this.
References
- Atterholt, J., and Wedel, M. 2018. A CT-based survey of supramedullary diverticula in extant birds. 66th Symposium on Vertebrate Palaeontology and Comparative Anatomy, Programme and Abstracts, p. 30 / PeerJ Preprints 6:e27201v1
- Cover, M.S. 1953. Gross and microscopic anatomy of the respiratory system of the turkey. III. The air sacs. American Journal of Veterinary Research 14:239-245.
- Müller, B. 1908. The air-sacs of the pigeon. Smithsonian Miscellaneous Collections 50:365-420.
- O’Connor, P.M. 2006. Postcranial pneumaticity: an evaluation of soft-tissue influences on the postcranial skeleton and the reconstruction of pulmonary anatomy in archosaurs. Journal of Morphology 267:1199-1226.
- Schwarz D, and Fritsch G. 2006. Pneumatic structures in the cervical vertebrae of the Late Jurassic Tendaguru sauropods Brachiosaurus brancai and Dicraeosaurus. Eclogae Geologicae Helvetiae 99:65–78.
- Wedel, M.J., and Sanders, R.K. 1998. Using computerized tomography to investigate sauropod cervical morphology. Journal of Vertebrate Paleontology 18, Supplement to Issue 3: 87A.
Aepyornis femora of the Oxford Museum of Natural History
March 18, 2018
By contrast to the very delicate pelican humerus and ulna in the previous post, here is the left femur of Aepyornis OUMNH 4950 — an “elephant bird” from Antolanbiby, Madagascar. It’s just a couple of meters away from the pelican, in the same Oxford gallery:
This is of course a ludicrously robust bone, as befits a gigantic ground-dwelling bird. But the fun thing is that it, too, is very pneumatic. You can see this in lots of ways: the foramina up at the top, the little patch of stretched texture at mid-length, and most of all in the honeycomb structure of the inside of the bone, which we can see where the cortex has broken off at both proximal and distal ends.
Birds: they’re made of air.
Yes, folks, birds and crocs can pee
January 28, 2016
Stand by . . . grumpy old man routine compiling . . .
So, someone at Sony decided that an Angry Birds movie would be a good idea, about three years after the Angry Birds “having a moment” moment was over. There’s a trailer for it now, and at the end of the trailer, a bird pees for like 17 seconds (which is about 1/7 of my personal record, but whatever).
And now I see these Poindexters all over the internet pushing their glasses up their noses and typing, “But everyone knows that birds don’t pee! They make uric acid instead! That’s the white stuff in ‘bird poop’. Dur-hur-hur-hurrr!” I am reasonably sure these are the same people who harped on the “inaccuracy” of the peeing Postosuchus in Walking With Dinosaurs two decades ago. (Honestly, how I didn’t get this written and posted in our first year of blogging is quite beyond my capacity.)
Congratulations, IFLScientists, on knowing One Fact about nature. Tragically for you, nature knows countless facts, and among them are that birds and crocodilians can pee. And since extant dinosaurs can and do pee, extinct ones probably could as well.
So, you know . . . try to show a little respect.
Now, it is true that crocs (mostly) and birds (always?) release more of their nitrogenous waste as uric acid than as urea. But their bodies produce both compounds. So does yours. We mammals are just shifted waaaay more heavily toward urea than uric acid, and extant archosaurs – and many (but not all) other reptiles to boot – are shifted waaaay more heavily toward uric acid than urea. Alligators also make a crapload of ammonia, but that’s a story for another time.
BUT, crucially, birds and crocs almost always release some clear, watery, urea-containing fluid when they dump the whitish uric acid, as shown in this helpful diagram that I stole from International Cockatiel Resource:
If you’ve never seen this, you’re just not getting to the bird poop fast enough – the urine is drying up before you notice it. Pick up the pace!
Sometimes birds and crocs save up a large quantity of fluid, and then flush everything out of their cloacas and lower intestines in one shot, as shown in the photos dribbled through this post. Which has led to some erroneous reports that ostriches have urinary bladders. They don’t, they just back up lots of urine into their colons. Many birds recapture some water and minerals that way, and thereby concentrate their wastes and save water – basically using the colon as a sort of second-stage kidney (Skadhauge 1976).
Many thanks to Markus Bühler for permission to post his well-timed u-rhea photo.
[UPDATE the next day: To be perfectly clear, all that’s going on here is that the birds and crocs keep their cloacal sphincters closed. The kidneys keep on producing urine and uric acid, and with no way out (closed sphincter) and nowhere else to go (no bladder – although urinary bladders have evolved repeatedly in lizards), the pee backs up into the colon. So if you’re wondering if extinct dinosaurs needed some kind of special adaptation to be able to pee, the answer is no. Peeing is an inherent possibility, and in fact the default setting, for any reptile that can keep its cloaca shut.]
Aaaanyway, all those white urate solids tend to make bird pee more whitish than yellow, as shown in the photos. I have seen a photo of an ostrich making a good solid stream from cloaca to ground that was yellow, but that was years ago and frustratingly I haven’t been able to relocate it. Crocodilians seem to have no problem making a clear, yellowish pee-stream, as you can see in many hilarious YouTube videos of gators peeing on herpetologists and reporters, which I am putting at the bottom of this post so as not to break up the flow of the rant.
You can explore this “secret history” of archosaur pee by entering the appropriate search terms into Google Scholar, where you’ll find papers with titles like:
- “Technique for the collection of clear urine from the Nile crocodile (Crocodylus niloticus)” (Myburgh et al. 2012)
- “Movement of urine in the lower colon and cloaca of ostriches” (Duke et al. 1995)
- “Plasma homeostasis and cloacal urine composition in Crocodylus porosus caught along a salinity gradient” (Grigg 1981)
- “Cloacal absorption of urine in birds” (Skadhauge 1976)
- “The cloacal storage of urine in the rooster” (Skadhauge 1968)
I’ve helpfully highlighted the operative term, to reinforce the main point of the post. Many of these papers are freely available – get the links from the References section below. A few are paywalled – really, Elsevier? $31.50 for a half-century-old paper on chicken pee? – but I’m saving them up, and I’ll be happy to lend a hand to other scholars who want to follow this stream of inquiry. If you’re really into the physiology of birds pooling pee in their poopers, the work of Erik Skadhauge will be a gold mine.
Now, to be fair, I seriously doubt that any bird has ever peed for 17 seconds. But the misinformation abroad on the net seems to be more about whether birds and other archosaurs can pee at all, rather than whether a normal amount of bird pee was exaggerated for comedic effect in the Angry Birds trailer.
In conclusion, birds and crocs can pee. Go tell the world.
And now, those gator peeing videos I promised:
UPDATE
Jan. 30, 2016: I just became aware that I had missed one of the best previous discussions of this topic, with one of the best videos, and the most relevant citations! The post is this one, by Brian Switek, which went up almost two years ago, the video is this excellent shot of an ostrich urinating and then defecating immediately after:
…and the citations are McCarville and Bishop (2002) – an SVP poster about a possible sauropod pee-scour, which is knew about but didn’t mention yet because I was saving it for a post of its own – and Fernandes et al. (2004) on some very convincing trace fossils of dinosaurs peeing on sand, from the Lower Cretaceous of Brazil. In addition to being cogent and well-illustrated, the Fernandes et al. paper has the lovely attribute of being freely available, here.
So, sorry, Brian, that I’d missed your post!
And for everyone else, stand by for another dinosaur pee post soon. And here’s one more video of an ostrich urinating (not pooping as the video title implies). The main event starts about 45 seconds in.
References
- Duke, G.E., Degen, A.A. and Reynhout, J.K., 1995. Movement of urine in the lower colon and cloaca of ostriches. Condor, 97, pp.165-173.
- Fernandes, M., Fernandes, L., Souto, P. 2004. Occurrence of urolites related to dinosaurs in the Lower Cretaceous of the Botucatu Formation, Paraná basin, São Paulo State, Brazil. Revista Brasileira de Paleontologia. 7(2), pp.263-268.
- Grigg, G.C., 1981. Plasma homeostasis and cloacal urine composition in Crocodylus porosus caught along a salinity gradient. Journal of Comparative Physiology, 144(2), pp.261-270.
- McCarville, K., Bishop, G. 2002. To pee or not to pee: evidence for liquid urination in sauropod dinosaurs. In: 62nd Annual Meeting of the Society of Vertebrate Paleontology, Abstract Book. Journal of Vertebrate Paleontology 22(3, Supplement), p. 85A.
- Myburgh, J.G., Huchzermeyer, F.W., Soley, J.T., Booyse, D.G., Groenewald, H.B., Bekker, C., Iguchi, T. and Guillette, L.J., 2012. Technique for the collection of clear urine from the Nile crocodile (Crocodylus niloticus). Journal of the South African Veterinary Association, 83(1), pp.1-7.
- Skadhauge, E., 1968. The cloacal storage of urine in the rooster. Comparative Biochemistry and Physiology, 24(1), pp.7-18.
- Skadhauge, E., 1976. Cloacal absorption of urine in birds. Comparative Biochemistry and Physiology Part A: Physiology, 55(2), pp.93-98.
What is my mystery baby bird?
September 23, 2015
Here’s my newest specimen: a tiny baby bird, maybe 5 or 6 cm from wingtip to foot. This one came from my next-door neighbours: apparently it had been sitting on their car for several weeks before they thought to lift it off and give it to me.
As you can see, the specimen is extraordinarily well preserved — more or less mummified, I suppose by wind-drying. Like a Chinese duck, though less appetising.
Here is the slightly flattened left side:
So I have two questions:
- What is this? Beyond the level of “a bird of some kind”.
- How can I prep it down to just a tiny skeleton? The only idea I have, really, is to slightly moisten it, and leave it in a tub with a hole in the top for inverts to get in. Can I do better?
Help me!
Sauropod Vertebra Picture of the Week 