In my recent visit to the LACM herpetology collection, I was interested to note that almost every croc, lizard, and snake vertebra I saw had a pair of neurovascular foramina on either side of the centrum, in “pleurocoel” position. You can see these in the baby Tomistoma tail, above. Some vertebrae have a big foramen, some have a small foramen, and some have no visible foramen at all. Somehow I’d never noticed this before.

This is particularly interesting in light of the observation from birds that pneumatic diverticula tend to follow nerves and vessels as they spread through the body. Maybe we find pneumatic features where we do in dinosaurs and pterosaurs because that’s where the blood vessels were going in the babies. Also, these neurovascular foramina in extant reptiles are highly variable in size and often asymmetric – sound familiar?

It should. Caudal pneumaticity in the tail of Giraffatitan MB.R.5000. Dark blue vertebrae are pneumatic on both sides, light blue vertebrae only have fossae on the right side. Wedel and Taylor (2013b: Figure 4).

I am starting to wonder if some of the variability we associate with pneumaticity is just the variability of soft tissue, full stop. Or if pneumaticity is variable because it developmentally follows in the footsteps of the blood vessels, which are themselves inherently variable. That seems like a promising line of inquiry. And also something I should have though of a lot sooner.


Juvenile Tomistoma schlegelii, LACM Herpetology 166483, with me for scale. It wasn’t until I picked up the skull that I realized it was the same specimen I had looked at back when. I was looking at its neck in 2011, and its tail today, for reasons that will be revealed at the dramatically appropriate moment. I was only playing with the skull because it’s cute, an intricate little marvel of natural selection. Photos by Vanessa Graff (2011) and Jessie Atterholt (2018). Many thanks to collections manager Neftali Camacho for his hospitality and assistance both times!

Ripple rock. Not from the Morrison, but from the overlying Dakota – Lower Cretaceous.

Now this is from the Morrison. My son, London, spotted this tiny tooth of a Jurassic croc while working in the quarry. That’s my thumb and London’s index finger for scale.

London’s index finger again, pointing at a different Morrison tooth. This one’s from a theropod, still exposed in a sandstone block in one of Stovall’s old quarries from the 1930s.

On a completely different hillside, I spotted this skull, of a modern rodent. Vole, maybe? Not my bailiwick, but if you know who this belongs to, let me know in the comments.

Moonrise – and the end of this post. Catch you in the future.

If you are within striking distance of Claremont, come watch me cross the streams of my amateur and professional careers as I talk about the intersection of astronomy and paleontology. And if you can’t make it in person, check out the livestream on the Raymond M. Alf Museum page on Facebook. Show starts Saturday, April 14, at 2:30 PM PDT.

Just got the APP new issue alert and there are three papers that I think readers of this blog will find particularly interesting:

That’s all for now, just popping in to let people know about these things.

ostrich peeing

cormorant peeing

alligator peeing

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.

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:

International Cockatiel Resource bird pee guide

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).

Rhea peeing by Markus Buhler

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.

ostrich excreting

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.

ostrich excreting 3

In conclusion, birds and crocs can pee. Go tell the world.

And now, those gator peeing videos I promised:


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.


Crocodiles vs. elephants

November 18, 2014

I’ve been reading The Guinness Book of Animal Facts and Feats (Wood 1982) again. Here’s what he says on pages 98-99 about the strength of crocodiles, and what happens when they bite off more than they can chew.

The strength of the crocodile is quite appalling. Deraniyalga (1939) mentions a crocodile in N. Australia which seized and dragged into the river a magnificent 1 tonne Suffolk stallion which had recently been imported from England, despite the fact that this breed of horse can exert a pull of more than 2 tonnes, and there is at least one record of a full-grown black rhinoceros losing a tug-of-war with a big crocodile. Sometimes, however, even crocodiles over-estimate their strength. One day in the 1860s a hunter named Lesley was a witness when a saurian seized the hind-leg of a large bull African elephant while it was bathing in a river in Natal. The crocodile was promptly dragged up the bank by the enraged tusker and then squashed flat by one of its companions who had hurried to the rescue. The victorious elephant then picked up the bloody carcase with its trunk and lodged it in the fork of a nearby tree (Stokes, 1953). Oswell (1894) says he twice found the skeletons of crocodiles 15 ft 4.6 m up in trees by the river’s bank where they had been thrown by angry elephants. On another occasion a surprised crocodile suddenly found itself dangling 15 ft 4.6 m in mid-air when it foolishly seized a drinking giraffe by the head.

The idea of elephants lodging crocodile corpses up in trees seems too bizarre to be true, but seeing it independently attested by two witnesses makes me more ready to accept it. There’s plenty of Internet chatter about this happening, but I’ve not been able to find photos — or better yet, video — proving that it happens.


  • Deraniyalga, P. 1939. The tetrapod reptiles of Ceylon, vol. 1: Testudinates and crocodilians. Colombo Nat. Mus., Ceylon.
  • Oswell, W. Cotton. 1894. South Africa fifty years ago. Badminton Library of Sports and Pastimes (Big Game Shooting), London.
  • Stokes, C. W. 1953. Sanctuary. Cape Town.
  • Wood, Gerald L. 1982. The Guinness Book of Animals Facts & Feats (3rd edition). Guinness Superlatives Ltd., Enfield, Middlesex. 252 pp.