Last spring I was an invited speaker at PaleoFest at the Burpee Museum of Natural History in Rockford, Illinois. I meant to get these photos posted right after I got back. But I flew back from Illinois on Monday, March 9, 2020, and by the following weekend I was throwing together virtual anatomy labs for the med students. You know the rest. 

The wall of ceratopsians at the Burpee Museum. Every museum should have one of these.

I had a fantastic time at PaleoFest. The hosts were awesome, the talks were great, the Burpee is a cool museum to explore, and the swag was phenomenal.

An ontogenetic series of Triceratops skulls. Check out how the bony horn cores switch from back-curving to forward-curving. The keratin sheaths over the horn cores elongated, but they didn’t remodel, so adult trikes probably had S-curving horns.

I know I poke a lot of fun at non-sauropods around here, but the truth is that I’m a pan-dino-geek at heart. When I’m looking at theropods and ceratopsians I am mostly uncontaminated by specialist knowledge or a desire to work on them, so I can relax, and squee the good squee.

I’m a sucker for dinosaur skin. It’s just mind-blowing that we can tell more or less what it would feel like to pet a dinosaur.

Among the memorable talks last year: Win McLaughlin educated me about rhinos, which are a heck of a lot weirder than I thought; Larisa DeSantis gave a mind-expanding talk about mammalian diets, evolution, and environmental change; and Holly Woodward explained in convincing detail why “Nanotyrannus” is a juvenile T. rex.

The pride of the Burpee Museum: Jane, the juvenile T. rex.

But my favorite presentation of the conference was Susie Maidment’s talk on stegosaurs. It was one of the those great talks in which the questions I had after seeing one slide were answered on the next slide, and where by end of the presentation I had absorbed a ton of new information almost effortlessly, by  just listening to an enthusiastic person talk almost conversationally about their topic. And when I say “effortlessly”, I mean for the audience–I know from long experience that presentations like that are born from deep, thorough knowledge of one’s topic, deliberate planning, and rehearsal.

The big T. rex mount is pretty great, too.

That’s not to slight the other speakers, of course. All the talks were good, and that’s not an easy thing to pull off. Full credit to Josh Matthews and the organizing committee for putting on such an engaging and inspiring conference.

Did I say the swag was phenomenal? The swag was phenomenal. Above are just a few of my favorite things: a Burpee-plated Rite-in-the-Rain field notebook, a fridge magnet, a cool sticker, and at the center, My Precious: a personalized Estwing rock hammer. Estwing makes nice stuff, and a lot of paleontologists and field geologists carry Estwing rock hammers. Estwing is also based in Rockford, and they’ve partnered with the Burpee Museum to make these personalized rock hammers for PaleoFest, which is pretty darned awesome.

I already had an Estwing hammer–one of blue-grip models–which is good, because the engraved one is going in my office, not to the field. (If you’re wondering why my field hammer looks so suspiciously unworn, it’s because my original was stolen a few years ago, and I’m still breaking this one in. By doing stuff like this.)

There’s a little Burpee logo with a silhouette of Jane down at the end of the handle, so I had to take Jane to meet Jane.

Parting shot: I grew up in a house out in the country, about 2 miles outside of the tiny town of Hillsdale, Oklahoma, which is about 20 miles north of Enid, which is about 100 miles north-northwest of Oklahoma City. Hillsdale is less than an hour from Salt Plains National Wildlife Refuge, where you can go dig for selenite crystals like the ones shown above. The digging is only allowed in designated areas, to avoid unexploded ordnance from when the salt plains were used as a bombing range in World War II, and at certain times of year, to avoid bothering the endangered whooping cranes that nest there.

I don’t know how many times I went to Salt Plains to dig crystals as a kid, either on family outings or school field trips, but it was a lot. I still have a tub of them out in the garage (little ones, nothing like museum-quality). And there are nice samples, like the one shown above, in the mineral hall of just about every big natural history museum on the planet. One of my favorite things to do when I visit a new museum is go cruise the mineral display and find the selenite crystals from Salt Plains. I’ve seen Salt Plains selenite in London, Berlin, and Vienna, and in most of the US natural history museums that I’ve visited for research or for fun. The farm boy in me still gets a little thrill at seeing a little piece of northwest Oklahoma, from a place that I’ve been and dug, on display in far-flung cities.

I already credited Josh Matthews for organizing a fabulous conference, but I need to thank him for being such a gracious host. He helped me arrange transportation, saw that all my needs were met, kept me plied with food and drink, and drove me to Chicago, along with a bunch of other folks, for a Field Museum visit before my flight home, which is how I got this awesome photo, and also these awesome photos. Thanks also to my fellow speakers, for many fascinating conversations, and to the PaleoFest audience, for bringing their A game and asking good questions. I didn’t know that PaleoFest 2020 would be my last conference for a while, but it was certainly a good one to go out on.

Someone on Facebook asked whether sauropods had subcutaneous fat, and by the time my answer hit five paragraphs I thought, “The merciful thing to do here is blog this and link to it.” So here are some things to keep in mind regarding the integumentary systems of sauropods.

Emu dissection at UC Santa Cruz back in 2004. Note the fat pad on the chest and how it abruptly comes to an end.

Sauropods may have had some subcutaneous fat – we can’t rule it out – but it probably wasn’t broadly distributed as it is in mammals. In the interaction of their air sac systems with connective tissue, sauropods were probably a lot like birds. Most birds don’t have subcutaneous fat all over their bodies. Instead, they have subcutaneous air sacs (or pneumatic diverticula) over parts or all of their bodies – in pelicans these are like bubble wrap under the skin, presumably for impact padding and insulation (Richardson 1939, 1943). The diverticula go everywhere and most places they go, they replace adipose tissue, even the harmless bits of fat between muscles that are basically the body’s packing peanuts (broiler chickens don’t count here, they’ve been artificially selected to be radically unhealthy). We suspect that sauropods had subcutaneous diverticula because so many other aspects of their pneumatic systems correspond to those of living birds (see the discussion in Wedel and Taylor 2013b for more on that).

Contrast the narrow line of adipose tissue down the ventral midline with the almost-completely-lean hindlimb.

That’s not to say that birds don’t have subcutaneous fat, just that it tends to be highly localized. Back in grad school I got to help dissect an emu (link) and a rhea (one, two), and in both cases the fat was concentrated in two places: huge paired fat pads over the pelvis, like big lozenges, and a concentration over the sternum with extensions along the ventral midline from the base of the neck to the cloaca. It was weird, the fat would be present and then it would just stop, like somebody flipped a switch. We pulled 18 lbs of fat off a 102-lb emu, so it wasn’t a trivial part of the body composition. IME, even relatively fatty birds like ducks tend to have the fat start and stop abruptly, and again, the fat deposits tend to be concentrated on the breast and tummy and over the hips.

Fat-tailed gecko, borrowed from here.

A lot of lizards and crocs and even some turtles carry fat deposits in their tails, and that is one aspect of sauropod anatomy that is definitely un-bird-like. So some sauropods might have had fat tails.

We can be pretty sure that at least some sauropods had thick skin. Osteoderms (armor plates) from Madagascar show that the bits that were embedded in the skin could be up to 7cm thick, so the surrounding skin was at least that thick and possibly even thicker (Dodson et al. 1998). And that was most likely on Rapetosaurus, which was not a huge sauropod. So giant sauropods might have had even thicker skin. Maybe. Remember that big-ass-ness (here arbitrarily defined as 40+ metric tons) evolved independently in:

They probably didn’t all get there looking the same way, beyond sharing the basic sauropod bauplan.

I’m too lazy to write about the fossil evidence for scaly skin and keratinous spines in sauropods – see this post and the references therein.

One final thing to think about is scar tissue. The scar tissue on the chest of a male elephant seal can be up to 5cm thick. Some sauropods might have had calluses or patches of scar tissue in predictable places, from combat, or habitually pushing down trees with their chests or tails, or doing whatever weird things real animals do when we’re not looking.

So in the toolbox of things to play with in reconstructing the integument of sauropods, we have thick skin, keratinous spines, osteoderms, fat pads (possibly concentrated over the hips and shoulders or on the tail), subcutaneous diverticula, calluses, and scar tissue. And that’s just the stuff we have found or reasonably inferred so far, barely 150 years into our exploration of animals we know mostly from bits and bobs, whose size means they mostly got buried in big sediment-dumping events that would not preserve delicate integumentary structures. Give us a millennium of Yixian Formations and Mahajanga Basins and Howe Quarries and the picture will probably change, and the arrow of history dictates that it will change for the weirder.

Likely? Probably not. But roll the evolutionary dice for 160 million years and you’ll get stranger things than this. Recycled from this post.

Finally, and related to my observation about big-ass-ness: sauropods were a globally-distributed radiation of animals from horse-sized to whale-sized that existed from the Late Triassic to the end of the Cretaceous. The chances that all of them had the same integumentary specializations, for display or combat or insulation or camouflage or whatever, are pretty darned low. Support weird sauropods – and vanilla ones, too.

Almost immediate update: I’ve just been reminded about Mark Witton’s excellent post on dinosaur fat from a couple of years ago. Go read that, and the rest of his blog. I’m sure I missed other relevant posts at other excellent blogs – feel free to remind me in the comments.