February 18, 2016
The idea that dinosaurs had unusual life histories is not new. The short, short version is that it is usually pretty straightforward to tell which mammals and birds are adults, because the major developmental milestones that mark adulthood – reproductive maturity, cessation of growth, macro-level skeletal fusions, histological markers of maturity – typically occur fairly close together in time. This is radically untrue for most dinosaurs, which started reproducing early, often well before they were fully grown, and for which the other signals of adulthood can be wildly inconsistent.
We don’t talk about this much in the paper, but one aspect of dinosaur life history should be of particular interest to sauropodophiles: most of the mounted sauropod skeletons in the world’s great museums belong to animals that are demonstrably not mature. They’re not the biggest individuals – witness the XV2 specimen of Giraffatitan, the giant Oklahoma Apatosaurus, and Diplodocus hallorum (formerly “Seismosaurus”).* They’re not skeletally mature – see the unfused scapulocoracoids of FMNH P25107, the holotype of Brachiosaurus mounted in Chicago, and MB.R.2181, the lectotype of Giraffatitan mounted in Berlin. And histological sampling suggests that most recovered sauropods were still growing (Klein and Sander 2008).
* The Oklahoma Museum of Natural History does have a mounted (reconstructed) skeleton of the giant Apatosaurus, and the New Mexico Museum of Natural History has a mounted reconstructed skeleton of Diplodocus hallorum. But as nice as those museums are, in historical terms those mounts are brand new, and they have not shaped the public – and professional – conception of Apatosaurus and Diplodocus to anywhere near the same degree as the much smaller specimens mounted at Yale, AMNH, the Field Museum, and so on.
Basically, very little of what we think we know about sauropods is based on animals that were fully grown – and the same problem extends to many other groups of dinosaurs.
This is kind of a methodological nightmare – a colleague on Facebook commented that he had pulled his hair out over this problem – and in the paper we suggest some ways to hopefully alleviate it. I mean, the biology is what it is, but we can minimize confusion by being really explicit about which criteria we’re using when we assign a specimen to a bin like “juvenile”, “subadult”, and so on.
Supposed Former Evolution Junkie
Personally, I’m more excited about the possibilities that dinosaur life history weirdness open up for dinosaur population dynamics and ecology.
Confession time: I am a recovering and relatively high-functioning evolutionary theory junkie. In grad school I was on the heavy stuff – I read tons of Gould and Dawkins and admired them both without being smitten by either. I took seminars on Darwin and evolutionary morphology, and lots of courses in ecology – ever mindful of Leigh Van Valen’s definition of evolution as “the control of development by ecology”. I read a fair amount of Van Valen, too, until “Energy and evolution” (Van Valen 1976) burned out most of my higher cognitive centers.
I say “recovering” evolutionary theory junkie because after grad school I mostly went clean. The problem is that dinosaurs are good for a lot of things, but exploring the inner workings of evolution is usually not one of those things. As products of evolution, and demonstrations of what is biomechanically possible, dinosaurs are awesome, and we can look at macroevolutionary patterns in, say, body size evolution or morphospace occupation, but we almost never find dinos in sufficient numbers to be able to test hypotheses about the tempo and mode of their evolution on the fine scale. I suppose I could have switched systems and worked on critters in which the machinations of selection are more visible, but for me even the charms of evolutionary theory pale next to the virulent allure of sauropods and pneumaticity.
Anyway, keeping in mind that Van Valenian dictum that evolution stands with one foot in the organism-internal realm of genes, cells, tissue interactions, and other developmental phenomena, and the other in the organism-external world of competition, predation, resource partitioning, demographics, and other ecological interactions, then it stands to reason that if dinosaurs had weird ontogenies – and they did – then they might have had weird ecologies, and weird evolution full stop. (Where by ‘weird’ I mean ‘not what we’d expect based on modern ecosystems and our own profoundly mammal-centric point of view’.)
Actually, we can be pretty sure that the weird ontogenies and weird ecologies of dinosaurs were intimately linked (see, for example, Varricchio 2010). Like the tyrannosaurs shown here – they didn’t all fill the same ecological niche. This casts some old arguments in a new light. Was T. rex adapted for fast running? Prrrrobably – just not as a full-size adult. The skeleton of an adult tyrannosaur is that of a 500 kg cursor pressed into service hauling around 10 tons of murder. And all of this has some pretty exciting implications for thinking about dinosaurian ecosystems. Whereas mammals tend to fill up ecospace with species, dinosaurs filled up their world with ecologically distinct growth stages.
Does all of this add up to weird evolutionary dynamics for dinosaurs? Possibly. As we say in the paper,
Correct identification of life stage also is relevant to fundamentals of evolution—if the onset of sexual reproduction substantially preceded cessation of growth in dinosaurs then the ‘adult’ phenotype may not have been the primary target of selection. In fact, once juveniles or subadults are capable of reproducing, it is conceivable a population could exist with potentially no individuals making it through the survivorship gauntlet into ‘adulthood’ and close to maximum body size. The occasional hints from the fossil record of anomalously large sauropods like Bruhathkayosaurus , and the Broome trackmaker  might be explained if many sauropods were primarily ‘subadult’ reproducers, and thus extremely large adults were actually vanishingly rare.
Did that actually happen? Beats me. But it’s consistent with what we know about sauropod life history, and with the observed scarcity of skeletally mature sauropods. And it might explain some other oddities as well, such as the high diversity of sauropods in seasonally arid environments like the Morrison Formation (see Engelmann et al. 2004), and the fact that sauropods – and large dinosaurs generally – are much larger than predicted based on the land areas available to them (see Burness et al. 2001). Because the age structure of sauropod populations was so skewed toward juveniles, the average body size of most sauropod populations was probably fairly modest, even though the maximum size was immense. So maybe a continuously reproducing population didn’t require as much food or space as we’ve previously assumed.
If we can falsify that, cool, we’ll have learned something. And if we can falsify the alternatives, that will be even cooler.
I’ll stop waving my arms now, lest I achieve powered flight and really inspire controversy. Many thanks to Dave and Andy for bringing me on board for this. It was a fun project, and we hope the paper is useful. You can read Dave’s thoughts on all of this here.
- Burness, G.P., Diamond, J. and Flannery, T., 2001. Dinosaurs, dragons, and dwarfs: the evolution of maximal body size. Proceedings of the National Academy of Sciences, 98(25), pp.14518-14523.
- Engelmann, G.F., Chure, D.J. and Fiorillo, A.R., 2004. The implications of a dry climate for the paleoecology of the fauna of the Upper Jurassic Morrison Formation. Sedimentary Geology, 167(3), pp.297-308.
- Klein, N. and Sander, M., 2008. Ontogenetic stages in the long bone histology of sauropod dinosaurs. Paleobiology, 34(2), pp.247-263.
- Van Valen, L., 1976. Energy and evolution. Evolutionary Theory, 1(7), pp.179-229.
- Varricchio, D.J., 2011. A distinct dinosaur life history? Historical Biology,23(1), pp.91-107.
August 21, 2014
I have often argued that given their long hindlimbs, massive tail-bases, and posteriorly-located centers of mass, diplodocids were basically bipeds whose forelimbs happened to reach the ground. I decided to see what that might look like.
Okay, now obviously I know that there are no trackways showing sauropods actually getting around like this. It’s just a thought experiment. But given how close the center of mass of Diplodocus is to the acetabulum, I’ll bet that this pose was achievable in life. If diplodocids had just pushed the CM a few cm farther back, they might have dispensed with forelimbs entirely, or done something different with them, like re-evolved grasping hands.
Image modified from Gilmore (1932: plate 6). Here’s a horizontal-necked bipedal Diplodocus and the original pose:
UPDATE the next day: I had forgotten that Niroot had already done a bipedal Apatosaurus, and a much more convincing one than mine. Go see it.
UPDATE the next week: Well, heck. Looks like the primary value of this post was so that people would remind me of all the other places the same idea has already been covered better. As you can see from the comment thread, Mike blogged about this at the WWD site, Scott Hartman drew it, and Heinrich Mallison showed that it was plausible. Sheesh, I suck.
- Gilmore, C. W. 1932. On a newly mounted skeleton of Diplodocus in the United States National Museum. Proceedings of the United States National Museum 81, 1-21.
April 22, 2014
5. Brian Kraatz, 2004
In the spring of 2004, I was killing time over in Tony Barnosky’s lab at Berekeley, talking to Brian Kraatz about something–mammals, probably. Brian told me that I should consider going to the International Congress of Zoology that was happening in Beijing that fall. He’d actually told me about it several times, but I kept forgetting about it. It seemed remote from my concerns. Finally, though, the day before the abstracts were due, I thought, “Why not?” I could get travel money from the department and it would get me over there to see a lot of Asian dinosaurs in person.
I was also intrigued because presenters could submit either abstracts or short papers, and I had an idea for a short paper. I had been thinking a lot about how pneumaticity got started in dinosaurs and how much we could infer about that, so that evening I stayed up until about 3 AM banging out what would become Wedel (2006), pretty much as it was published, except for the figure, which was added later.
That got me to Beijing, where I spent a lot of time talking with Paul Barrett, who saw my talk and later invited me to contribute a talk to an SVP symposium on prosauropods, which grew into Wedel (2007) and became a chapter of my dissertation. And that got me an invite from Adam Yates and Matt Bonnan to join them in writing up the first really solid evidence of pneumaticity in prosauropods (Yates et al. 2012).
When I wandered over to the Barnosky lab to kill time that day, Brian wasn’t in. Instead I got to talking with Alan Shabel about food webs in East African riparian ecosystems. The habitats and faunas he was talking about put me in mind of the Morrison Formation of the American West. I wondered if the quantitative ecological analysis that Alan was working on would yield any insights into how Late Jurassic ecosystems worked. And that fired a few neutrons at the Van Valen papers I’d been reading for Kevin Padian’s paleobiology seminar, and precipitated a chain reaction. The paper that came out of that, “Sauropod dinosaurs as Van Valen’s energy maximizers”, was published in Paleobiology in 2007. That’s how I got into quantifying energy flow through dinosaur-dominated ecosystems.
I was presenting some of that work at an ecology conference in 2008 when I got invited to join a team of biologists going to the Galapagos. I was particularly interested in the role of extant dinosaurs (i.e., birds) in ecosystems dominated by bradymetabolic reptiles. Some of the data from that trip and one subsequent expedition went into my 2013 paper on the rise of dinosaurs during the Triassic. But most importantly, it got me working in the Galapagos, which I had wanted to do ever since I was a kid.
4. Mike Taylor, 2000
My first paper came out in the first issue of the Journal of Vertebrate Paleontology in 2000. It was the one in which Rich Cifelli and Kent Sanders and I designated OMNH 53062, a string of four sauropod vertebrae from southeast Oklahoma, as the type specimen of a new dinosaur, Sauroposeidon proteles. I had been collecting business cards and mailing addresses from people at SVP since 1997, and I had a list of about 100 people that I thought would appreciate a reprint of the paper. So when the reprints arrived from the publisher, I printed out a bunch of form letters, made an assembly line of reprints, letters, and envelopes on the big table in the OMNH vert paleo library, and killed an afternoon getting everything assembled and ready to ship out.
Also about this time I received a polite email from some English guy named Mike Taylor, asking for a reprint. I wrote back and said that I’d be happy to send him one. I don’t know what he wrote back next, but it was sufficiently interesting that it kicked off a conversation that has now been going on for 14 years. When Vicki and I went to England on spring break in 2004, we stayed with Mike and Fiona in London. I went back over for SVPCA in London in 2005, and after 2009, I started going to SVPCA every year instead of SVP. That’s how I got to know Dave Hone. I got acquainted with Darren separately–we were sending each other reprints in 2001, I think, and talking sporadically about brachiosaurs. I think that Mike and Darren also met separately, and possibly if I hadn’t been around, they still would have ended up working together. But my papers with Mike–which account for seven of the nine I’ve published since my dissertation–wouldn’t have happened, or would have come out very differently. And you wouldn’t be reading this blog.
I first met Mike Taylor at the SVP meeting in Bristol in 2009. He had done that paper on that weird vertebra with Darren a couple of years before. We got together over a few pints and discovered that we had a lot of interests in common–Star Wars, Tolkien, C.S. Lewis–but c’mon, who can’t you say that about in this geek-infested business? He’s a nice guy, and we’re friends, but we’re not what you’d call close.
I spent most of my time at that meeting catching up with Matt Bonnan. We’d been friends since the late 90s, and we’d written the paper on the probable brachiosaurid metacarpal in 2004, but we hadn’t collaborated much. Well, we were both out of grad school and into stable jobs, and we really put our heads together that meeting. Two streams of papers came out of that: first, the sauropod biomechanics papers, which merged his limb development stuff with my pneumaticity stuff, and secondly, all of our work on quantifying serial variation using geometric morphometrics.
Although the first set of papers has attracted more attention–certainly more media attention–it’s the second set that give me more satisfaction. I’ve always been interested in serial homology, I just didn’t have a novel approach. But with Matt’s help I was able to combine morphometrics and phylogenetics to produce developmental phylogenies of serially repeated structures. That by itself is pretty cool, but when you bring it into the extant realm you can put the gene expression patterns right into the analysis. The stuff we’re doing with axial development in chickens right now–man, I don’t know if I’ll ever find the time to write another paper about extinct dinosaurs, when there’s so much fun to be had with the living ones.
3. Brooks Britt, 1997
In the summer of 1997, I was on a multi-thousand-mile quest to determine whether OMNH 53062 was a new dinosaur, or just a big example of something already known. Vicki and I had been to D.C. that spring, partly as our first vacation as a married couple, and partly so that I could see the Astrodon/Pleurocoelus material at the Smithsonian. That summer, I mapped out an epic tour of museums in the West. With our friend Tyson Davis, Vicki and I went to Dinosaur National Monument, the Utah Museum of Natural History in Salt Lake, the BYU Earth Sciences Museum in Provo, and the Museum of Western Colorado in Grand Junction.
The main reason we went to Grand Junction was because at the time, the MWC had some of the BYU Brachiosaurus material from Dry Mesa Quarry on exhibit. Rich Cifelli and I weren’t sure what OMNH 53062 was yet, but we thought it looked an awful lot like Brachiosaurus. Brooks Britt was the curator there at the time, and he took us down to the basement and showed us some of the sauropod material from the Lower Cretaceous Dalton Wells Quarry. Brooks was particularly excited to show us the pneumatic features in the vertebrae. I told him about the big vertebrae from Oklahoma that I was working on, and he said, “You should get those vertebrae CT scanned, to get a look at the pneumatic spaces inside.” I smiled and nodded and thought to myself, “Dude, you are completely crazy. I am an undergrad on an independent study. No way do I have the juice to get giant dinosaur bones CT scanned.” But I didn’t forget about what he’d said. When we got back to Oklahoma, I mentioned it to Rich–and then I forgot about it.
Happily for me, Rich did not forget about it. A few months later, he was at a university function with the director of OU’s University Hospital, and he mentioned the idea of CT scanning the dinosaur bones. The hospital director was all for it–the CT machines frequently had down time on Saturdays, and the hospital would trade time on the machines for publicity when we published our results. That December, I was in Rich’s office for one of our weekly meetings when he said, “Hey, are you still interested in CT scanning the vertebrae? Because if you want to, we can make it happen.” I don’t remember what I said, but I assume it was some variant of “Hell yeah!”
We took the first jacket up to the hospital in January, 1998. We got decent results. The vertebrae were so big and dense that the scans were plagued by beam-hardening artifacts, but we could see that internal structure was honeycombed by dozens or hundreds of thin-walled cavities. The problem was, we had no idea what that meant–a few physical cross-sections of sauropod vertebrae had been published over the years, most notably by Heber Longman in 1933 and Werner Janensch in 1947–but to my knowledge no CT scans of sauropod vertebrae had ever been published, and you could probably count on your fingers the number of published CT scans of fossils of any kind. Brooks had a bunch in his 1993 dissertation, but that was unpublished, and I wouldn’t get a copy for several more months. So we had no baseline.
But we did have Kent Sanders, a radiologist at the hospital who was hot on this stuff and helped us read the films. And we had a museum full of dinosaur bones and access to a CT scanner on the weekends. So that’s how I spent most of the Saturdays in 1998–drive to the museum, fill the trunk of the car with dinosaur bones, drive up to Oklahoma City and spend the day scanning with Kent. I wasn’t supposed to do my MS thesis on pneumaticity, but when the primary project I had been working on didn’t look like it was going to pan out, I realized that I had enough CT scans of sauropod vertebrae that with a little selective hole-filling I could describe the evolution of vertebral pneumaticity in sauropods. So that became my Master’s thesis.
That conversation with Brooks Britt in the summer of 1997 was a turning point for me. Until then I’d been interested in OMNH 53062 for what it could tell us about the animal that it had once been part of. But when Brooks started telling me about the taphonomy of the Dalton Wells Quarry, I realized that the Oklahoma vertebrae were telling another story, too: the story of what had happened to that animal. So that’s the angle we played up in the paper–how did these vertebrae get separated from the rest of the critter? Mesozoic murder mystery!
Then the next summer I was out with Rich’s crew in Montana, working in the Cloverly Formation. I actually spent most of my time with Des Maxwell and his group at the Wolf Creek quarry, which was a sauropod bonebed. I did a poster on that quarry for SVP in 2000, and I wrote my MS thesis on the taphonomy of the quarry.
While all of this was going on, I was spending more and more time talking with Brooks Britt. He had done his dissertation on pneumaticity in fossil archosaurs, but he had all kinds of interesting things going on related to taphonomy, including modification of dinosaur bones by termities, and evidence of fungal hyphae in dinosaur bones. Brooks had done his Bachelor’s and Master’s work at BYU before going to Calgary for his dissertation. He encouraged me to think about going to BYU for my PhD work. The more I thought about it, the more sense it made–I freaking love Utah, and the chance to go live and work there was too good to pass up. I started out as one of Ken Stadtman’s grad students, but when Brooks got the job at BYU in 2002, he agreed to come on as my co-advisor. I’m mainly interested in what you can infer about terrestrial ecosystems from tracks left on bones, so that’s what I did my dissertation on. Most of the chapters were on sauropods, naturally, but I did have that one project looking at invertebrates, fungi, and microbes–or their traces–in faunal bone I collected from Capitol Reef National Forest in the summer of 2005. Now that was a fun project.
While I was working at BYU, Vicki got her PhD in anthropology from the University of Utah. Both of us had field sites in southern Utah, and we really fell in love with that part of the state. After we finished our degrees we moved to St. George, which is just gorgeous. Vicki coordinates the excavation and repatriation of Native American remains and artifacts from Utah federal lands, and I teach geology at Dixie State University. When I’m not digging, teaching, or hiking, I blog about sauropod taphonomy. My friends tease me because it’s such a geeky niche thing, but it makes me happy.
2. Rich Cifelli, 1996
You know how sometimes you end up working on something just because it’s there? That’s how I started working on sauropods.
Immediately after I left Trish Schwagmeyer’s office, I marched down to the museum, barged into Rich’s office, threw myself in a chair, and asked him if he’d sponsor me on an independent study. He said that he’d be delighted to–what did I want to work on? Dinosaurs, I said, dinosaurs! “Well, we have these big sauropod vertebrae from southeastern Oklahoma that need to be identified.” We went and had a look. It wasn’t my dream project–I was more interested in big theropods and ceratopsians–but I said I’d take the job. There was a little paperwork to fill out. We conceived a one-semester project, to be completed in the fall of 1996, to identify the specimen, OMNH 53062, to the family level. Rich loaned me some of his sauropod papers to photocopy so that I could get up to speed on the anatomy. I spent the fall of 1996 grokking sauropod vertebral morphology and trying to figure out what this thing was.
Immediately after I left Trish Schwagmeyer’s office, I marched down to the museum, barged into Rich’s office, threw myself in a chair, and asked him if he’d sponsor me on an independent study. He said that he’d be delighted to–what did I want to work on? Dinosaurs, I said, dinosaurs–especially big theropods or ceratopsians! “Well, we have these ceratopsian odds and ends that Stovall collected back in the 30s and 40s. They’ve been catalogued all this time as Pentaceratops and Triceratops, but someone should probably check on those IDs.” Wow, my dream project–of course I pounced on it! There was a little paperwork to fill out. We conceived a one-semester project, to be completed in the fall of 1996, to identify the specimens to the genus level. Rich loaned me some of his ceratopsian papers to photocopy so that I could get up to speed on the anatomy. I spent the fall of 1996 grokking ceratopsian cranial morphology and trying to figure out what those things were.
Well, it turns out that they were Pentaceratops and Triceratops after all. So no big news, but I did learn a lot on that project: how to photograph and measure fossils, how to read scientific papers. Mostly it just got me back in the museum.
You know how sometimes you end up working on something just because it’s there? That’s how I started working on Tenontosaurus. I’ll confess, at first I didn’t have any deep, abiding love for “Tonto”. I scorned it as the world’s most boring dinosaur–no horns, spikes, frills, claws, or sails, basically just a scaly cow with a longer tail. But, man, these things were pouring out of the Antlers Formation like water out of a tap. We had adults, subadults, big juveniles, little juveniles, even a few bones from individuals so small they must have been yearlings. I started working on them in my spare time, and got a little project going on the post-hatching ontogeny of Tenontosaurus. When I graduated with my BS in the fall of 1997, it just made sense to stick around and keep working on Tenontosaurus for my MS.
Naturally I was presenting this stuff at SVP every fall, and that’s where I met Jack Horner. He thought my ontogenetic work on Tenontosaurus would be good preparation for tackling hadrosaur ontogeny and diversity. So I went to MSU for my PhD work. After I finished I got the job I have now, teaching geology in Missouri. Even when I was living in Montana, I’d still get into the OMNH collections for a day or two of research whenever I was back in Oklahoma. Now that I’m just five hours away, I’m back at OMNH all the time. There’s just so much to work on–Eolambia, the small ornithopod material from the Cloverly Formation, and especially the teeth. The OMNH has hundreds of these little ornithopod teeth from the microsites in the Cedar Mountain Formation, the Cloverly Formation, and the Antlers Formation. Nobody wants to work on them, except me. While I was working on Tenontosaurus I had to come up with some size-independent characters that I could use to determine the ontogenetic age of ornithopods based on their teeth. Once I had those, all of those teeth catalogued as “Ornithopoda indet.” became a goldmine.
I certainly never saw myself becoming “the ornithopod tooth guy”–what an oddly specific thing to be an expert on! But to me they are beautiful, intricate, and endlessly fascinating. Who knows, maybe one of these days I’ll take all of my best photographs and start a Tumblr.
1. Trish Schwagmeyer, 1996
Trish: “You’re blowing it. You want to do research, but no-one is going to trust you with a project if you can’t take care of the basic stuff like keeping your grades up.”
Me: [face-burning, fully convicted silence]
Trish: “You are capable of much more than this. I know that these grades are not reflective of your best work. This is your chance to prepare yourself for the career you want. You owe it to yourself to do better than this.”
Me: [sucking it up] “I understand. And I’ll do better. Other than getting my grades up, what else can I do to make myself attractive to graduate programs?”
Trish: “Find a professor that you like and do an independent study. Get some research experience.”
Yow. I will remember that for as long as I live. “You’re blowing it.” Thank God that alone out of everyone in my life, Trish Schwagmeyer had the guts to look me in the eye and call me out.
Trish: “Your grades last semester were a little rough.”
Me: “Yeah. O-chem II was murder.”
Trish: “And biochem.”
Me: “Yeah. Biochem.”
Trish: “Have you noticed that you get As and Bs in your language and history classes, and Cs in your math and science classes?”
Me: “Yeah, of course. Math and science are hard. Language and history are…”
Trish: “Are what?”
Me: “I dunno. Fun. More like play.”
Trish: “Maybe you’re in the wrong major.”
Yow. I will remember that for as long as I live. “Maybe you’re in the wrong major.” Thank God that alone out of everyone in my life, Trish Schwagmeyer had the guts to look me in the eye and diagnose the problem.
Immediately after I left her office, I marched over to the registrar and changed my major from Zoology to Letters. And breathed a huge sigh of relief. After that, I just cruised. I got my degree, stayed at OU for a Master’s in classical languages, and now I teach Latin at a private high school in Oklahoma City. I should have known that a career in science wasn’t in the cards. The evidence was written all over my transcript. Paleontology is still interesting to me–I doubt if I will ever stop being fascinated by dinosaurs–but it just wasn’t a realistic career option. I’m so glad I found my true calling.
September 11, 2013
We’ve blogged a lot of Bob Nicholls‘ art (here, here, and here) and we’ll probably continue to do so for the foreseeable future. We don’t have much choice: he keeps drawing awesome things and giving us permission to post them. Like this defiantly shaggy Apatosaurus, which was probably the star of the Morrison version of Duck Dynasty. Writes Bob:
On my way home at the airport I did a sketch of your giant Apatosaurus* — see attachment. My thought was that massive thick necks were probably pretty sexy things to apatosaurs, so maybe sexually mature individuals used simple feathers (stage 1, 2 or 3?) to accentuate the neck profile. The biggest males would of course have the most impressive growths so in the attached sketch your giant has one of the biggest beards in Earth’s history! What do you think of this idea?
Well, I think it’s awesome. And entirely plausible, for reasons already explained in this post.
“Now, wait,” you may be thinking, “I thought you guys said that sauropod necks weren’t sexually selected.” Actually we made a slightly different point: that the available evidence does not suggest that sexual selection was the primary driver of sauropod neck elongation. But we also acknowledged that biological structures are almost never single-purpose, and although the long necks of sauropods probably evolved to help them gather more food, there is no reason that long necks couldn’t have been co-opted as social billboards. This seems especially likely in Apatosaurus, where the neck length is unremarkable** but the neck fatness is frankly bizarre (and even inspired a Star Wars starfighter!).
I also love the “mobile ecosystem” of birds, other small dinosaurs, and insects riding on this Apatosaurus or following in its train. It’s a useful reminder that we have no real idea what effect millions of sauropods would have on the landscape. But it’s not hard to imagine that most Mesozoic terrestrial ecosystems were sauropod-driven in a thousand cascading and ramifying chains of cause and effect. I’d love to know how that worked. At heart, I’m still a wannabe chrononaut, and all my noodlings on pneumaticity and sauropod nerves and neural spines and so on are just baby steps toward trying to understand sauropod lives. Safari by way of pedantry: tally-ho!
For other speculative apatosaurs, see:
** Assuming we can be blasé about a neck that is more than twice as long (5 m) as a world-record giraffe neck (2.4 m), for garden variety Apatosaurus, or three times that length for the giant Oklahoma Apatosaurus (maybe 7 m).
July 26, 2013
Now, for me to try to draw dinosaurs next to Brian is more than a little intimidating. I really felt the need to bring my A-game. So this is what I came up with. I’m posting it not because I think it is particularly likely* but because the blog has been a little sauropod-lite this summer, and heck, it’s Friday.
* Although frigatebirds and anoles and such might have some things to say about that.
This post is just an excuse for me to show off Brian Engh’s entry for the All Yesterdays contest (book here, contest–now closed–here). The title is a reference to this post, by virtue of which I fancy myself at least a spear-carrier in what I will grandly refer to as the All Yesterdays Movement.
Oddly enough, I don’t have a ton to say about this; I think Brian has already explained the thinking behind the piece sufficiently on his own blog. In the brave new world of integumentarily enhanced ornithodirans, these diamantinasaurs are certainly interesting but not particularly outlandish (Brian’s already done outlandish). And it’s pretty darned hard to argue that sauropods never went into caves, although I can’t off the top of my head think of any previous spelunking sauropods (I’m not counting Baylene in Disney’s Dinosaur; feel free to refresh my memory of others in the comments). The glowworms are not proven, but biogeographically and stratigraphically plausible, which is probably as good as we’re going to get given the fossilization potential of bioluminescence.
I’m much more excited about this as a piece of art. I got to see a lot of the in-progress sketches and they were wonderful, with some very tight, detailed pencil-work. The danger in investing that kind of effort is that then you’re tempted to show it off, and if I had any worry about the finished piece, it was that it would be over-lit to show off all the details. But it isn’t. I can tell you from seeing the pencil sketches that the detail went all the way down, but Brian was brave enough to let some of that go, especially on the animals’ legs, to get the lighting effect right. My favorite touches are the reflections in the water, and the fallen pillar in the foreground–toppled by a previous visitor, perhaps–with new mineral deposits already forming on it.
All in all, it takes me back to the best paleoart from my childhood, which made me think, “Wow, these were not monsters or aliens, they were real animals, as real, and as mundane in their own worlds, as deer and coyotes and jackrabbits.” * **
And that’s pretty cool. What do you think?
* Okay, maybe not in those exact words. I am translating a feeling I had when I was nine through 28 years of subsequent experience and vocabulary expansion.
** My major discovery in the last two decades is that deer and coyotes and jackrabbits are just as exotic as dinosaurs, if only you learn to really see them. And before Mike jumps me for saying that, I said ‘just as exotic’, not ‘just as awesome‘.
UPDATE the next day
That’s game, set, and match on the glowworm issue.
February 27, 2013
Well, this is rad. And adorable. Brian Switek, whom we adore, commissioned a fuzzy juvenile sauropod from Niroot, whom we adore, for his (Brian’s) upcoming book, My Beloved Brontosaurus, which I am gearing up to adore. And here is the result, which I adore, borrowed with permission from Love in the Time of Chasmosaurs.
There is much to like here. Here’s my rundown:
- Small forefeet that are the correct shape: good. Maybe too small, given that young animals often have big feet. But better too small than too big, given how often people screw this up.
- Pronounced forelimb-hindlimb disparity: win.
- Fat neck: pretty good.
In fact, let me interrupt the flow of praise here to put in Brant Bassam’s dorsal view of his mounted Phil Platt model Apatosaurus skeleton. I’ve been meaning to post about this for a while now and haven’t gotten to it, so now’s a good time: just look at how friggin’ FAT that neck is, and how it blends in with the body, and how the tail gets a lot skinnier a lot quicker (and, yeah, caudofemoralis, but not that much). Now, go look at a bunch of life restorations of Apatosaurus–drawings, paintings, sculptures, toys, whatever–and see how many people get this wrong, by giving Apatosaurus a too-skinny neck. The answer is, damn near everyone.
Okay, back to Niroot’s baby:
- Proportionally shorter neck and tail because it’s a juvenile: win.
- Neck wrinkles possibly corresponding to vertebrae: okay, just this once.
- Greenish fuzz possibly functioning as camouflage: We-ell…
Yes, it’s true that all of the known sauropod skin impressions show scales, not fuzz. But. We don’t have anything like full-body coverage. And I suspect that there is a collection bias against fuzzy skin impressions. Scaly skin impressions are probably easier to recognize than 3D feathery skin impressions (as opposed to feathers preserved flat as at Liaoning and Solnhofen) because the latter probably just look like wavy patterns on rock, and who is looking for feather impressions when swinging a pickaxe at a sauropod’s back end? And how many sauropods get buried in circumstances delicate enough to preserve dinofuzz anyway? Also, some kind of fuzz is probably primitive for Ornithodira, and scales do not necessarily indicate that feathers were absent because owl legs. So is this speculative? Yes. Is it out of the question? I think not. In the spirit of Mythbusters, I’m calling it ‘plausible’.
Oh, one more thing: Niroot posted this in honor of Brian Switek’s birthday. Happy birthday, Brian! (You owe me a book!)