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The Second International Workshop on the Biology of Sauropod Dinosaurs (part II)

The views expressed are those of the author and are not necessarily those of Scientific American.


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An average day in the Mesozoic. This >definitely< happened! Illustration by Luis Rey.

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And the ornithodiran biology fest hasn’t stopped yet… I still need to finish up on the events of the sauropod biology workshop, the three-day meeting held in December 2011 at the University of Bonn, Germany. For part I of my thoughts, please go here.

Having finished with feeding and digestion, an entire session was then devoted to sauropod reproduction and life history. This is one of those areas that we long to know more about – there isn’t much direct data, so what we can infer based on the extensive information we have on other animals? Jan Werner used data from extant animals to argue that body mass is correlated with reproductive investment, but predicted sauropod clutch sizes differ if we assume avian rates or ‘reptilian’ rates. Counter-intuitively, perhaps, an avian model predicts a much higher annual egg number.

One of the most characteristic bits of a sauropod. Diagram compiled by Mike Taylor.

Physiology and growth rates formed the subject of a few talks. Thomas Tütken explained clumped isotope thermometry (CIT) and what it might mean for sauropod body temperatures. This work is reasonably well known thanks to Eagle et al.’s (2011) paper in Science. The isotopic data seem to show that sauropods had a body temperature similar to that of endothermic mammals, and 4-7 degrees C lower than would be expected if they were mass homeotherms. Romain Amiot’s talk focused on Cretaceous thermal regimes and how they might correlate with sauropod distribution. He spoke in particular about the recent work showing that Early Cretaceous Liaoning was apparently cool-temperate (mean air temperature something like 10 deg C) (Amiot et al. 2011). And, yes, there was some discussion afterwards about the absence vs presence of crocodilians at Liaoning. Note that, even if they are there, they’re evidently very rare.

Data from osteocyte lacunae, discussed by Koen Stein, seem to provide further support for the concept of elevated metabolisms in Mesozoic dinosaurs. Steven Perry spoke about sauropod lung structure (as inferred from crocodilians and birds). Thanks to recent work on crocodilian lungs, we now know that unidirectional airflow is not unique to birds (Farmer & Sanders 2010), but probably evolved early on in archosaur evolution. The crazy-long tracheae and oesophagi that sauropods must have had raise all kinds of questions about breathing, vocalising, swallowing and exchanging heat, but we just don’t have enough information to answer those questions in meaningful fashion. Yet. Could cooling of inspired air in the upper part of the respiratory tract contribute to temperature control?

Vertebral pneumaticity in the non-sauropod Plateosaurus; photo by Matt Wedel.

Matt Wedel reviewed current thoughts and recent developments on sauropod pneumaticity. The absence of skeletal pneumaticity in sauropodomorphs other than sauropods and Pantydraco turns out to mostly be an artefact of not looking hard enough, since recent work has discovered pneumatic vertebral features in Plateosaurus [adjacent photo from here on SV-POW!], Aardonyx and elsewhere among ‘prosauropods’ (Yates et al. in press). And additional recent work has discovered previously overlooked pneumaticity in the tails of several well known sauropods: the cases concerned are particularly interesting since they involve numerous pneumatic hiatuses (where pneumatic diverticula must have been present, yet ‘skipped’ vertebrae without leaving any bony traces). Within the context of what we know about archosaur pneumaticity, ornithischians remain an enigma – did they really lack skeletal pneumatisation entirely, or have people overlooked it, as they long did with prosauropods? Or is it that ornithischians had diverticula, but failed to pneumatise their bones? Regular readers will know about the claimed pneumaticity of the iguanodontian Delapparentia, but this isn’t at all convincing.

Matt Wedel's opening slide. Photo by Vanessa Graff.

We now have so much data on skeletal pneumatisation in sauropods (and other fossil dinosaurs) that it’s difficult to see where research progress might occur – we aren’t going to disprove the hypothesis of sauropod pneumaticity. So – what next? Inspired by the digital modelling work of Heinrich Mallison, Don Henderson and others, Matt suggests that sauropod palaeobiologists work together to construct a digital sauropod that might be used to examine many of our questions about physiology, airflow, temperature gradients across the extremities and so on.

Neck Wars! (continued)

And so, by inevitable progress, we were on to necks. Some of you will know of the Neck Wars, the very much tongue-in-cheek term we use for the academic disagreement that continues between those who think that sauropods could and did raise their necks up high, and those who think that sauropods were more or less constrained to perpetual sub-horizontal neck poses.

Mike Taylor discussed his work on articular cartilage in necks and what it might mean for sauropods (a subject I covered in my discussion of the Lyme Regis SVPCA meeting). Kent Stevens gave a talk essentially similar to the one he presented at SVPCA in Cambridge in 2010 (see discussion here at Tet Zoo ver 2). Kent claimed that there are a number of ‘myths’ circulating about neck postures and the nature of zygapophyseal articulations and that various of the statements made by Taylor et al. (2009) can be challenged. It would be futile for me or my co-authors to respond to Kent’s many points in front of an audience, so our strategy has been (and still is) to hold back and wait until there’s something published to respond to. I want to make one point here though. When you see the neck of a mounted skeleton in a museum, you are not seeing that neck in ONP (osteological neutral pose), nor are you seeing the normal, alert neck pose of the species in question. Rather, people have deliberately posed the skeletal neck you’re looking at to match the angle and posture of the flesh-and-blood neck of the animal when it was alive. But we know from x-rays and dissections that (with exceptions, like flamingos) the angle of the neck skeleton is not the same as the angle of the neck with all of its soft tissues in place. If you’re interested, there a whole article on this specific issue over at SV-POW!

X-rays of diverse living animals show that extension is the norm at the cervico-dorsal junction, and flexion the norm at the cranio-cervical joint. Furthermore, note that the angle and pose of the neck SKELETON is often more vertical than what you'd expect based on the neck's soft tissue outline.

Nicole Klein presented histological data that essentially confirmed what some of us have suspected for a while: that the (often ultra-long) ‘cervical ribs’ of sauropods are actually ossified tendons. Vanessa Graff followed up with an excellent discussion of the ‘ventral bracing’ hypothesis: the idea – published by Martin et al. (1998) and supported by various members of the German Konstruktion Morphologie school – that the cervical ribs somehow prop up against one another and form continuous, permanently loaded, uncompressible struts that run along the bottom of the neck. This model was inspired by the ventral bracing system supposedly present in crocs. But… it isn’t actually present in crocs at all, and there are loads of reasons why it just can’t work. For the record, we know that sauropods also had a dorsal interspinous ligament, and we reasonably infer that they had bird-like neck muscles as well, so it’s not as if they were devoid of other structures that contributed to neck support.

Finally on necks, Don Henderson used mathematical modelling to examine the dynamics of heat loss on the sauropod neck.

Naish, speaking about the 'necks for sex' hypothesis. Many points if you know what's on the screen.

Armitt Schmitt spoke about his work on sauropod inner ear morphology and what it might mean for palaeobiology. I gave the very last talk – a summary of the paper that I and colleagues published in response to Senter’s idea that the sauropod neck might have evolved as a sexual display structure (Senter 2007, Taylor et al. 2011). It was the very last talk of the meeting, so I kept it light and included as many jokes and hilarious images as possible. For time reasons I had to cut out a brief section on mutual sexual selection – kind of frustrating since I wanted to present this phenomenon to the audience. Indeed, the Taylor et al. (2011) paper evaluating Senter’s ‘necks for sex’ hypothesis and the Hone et al. (2011) paper on mutual sexual selection in dinosaurs and pterosaurs can be regarded as linked projects.

And that was it. Three whole days of discussion and debate on just about all aspects of sauropod biology. I believe that most of the talks were filmed, and at some stage they’ll be viewable online. I’ll include a link when I can. How did the gigantism hypothesis hold up relative to the new data, and new ideas, presented and discussed at the meeting? In general it stood up well, and most new research fits into the idea that (as discussed in the part I article) the long sauropod neck, avian-style respiration system and absence of mastication combined with a high metabolic rate and rapid production of babies to allow the evolution of superlative size.

I’ve never been to Bonn before. I got to see some nice fossils, including the holotype of the pterosaur Scaphognathus crassirostris, mounted Oxford Clay Ophthalmosaurus and Cryptoclidus specimens and numerous Triassic marine reptiles (soooo many nothosaurs, drool). As usual, it was a great social event. There was a lot of beer.

Participants of the 2nd International Workshop on Sauropod Biology and Gigantism. Photo by Philipp Sander, and with thanks to Carole Gee and Martin Sander.

On that note, I think I should stop. Hopefully I’ve given you a good idea of where we’re at with respect to the biology of these most remarkable animals. Substantial areas of confusion and disagreement remain, and I’m sure the next meeting will be equally interesting. If you haven’t been keeping an eye on the many comments (now over 60) that were appended to the part I article, do go and have a look. We ended up talking quite a lot about the whole dinosaur endothermy thing. Again.

For previous Tet Zoo articles on the biology of sauropods and other Mesozoic dinosaurs, please see…

UPDATE: while we’re here… some of you will be aware of the Research Works Act, a vile, nefarious attempt by some academic publishers to RESTRICT ACCESS TO ACADEMIC PUBLICATIONS AS MUCH AS POSSIBLE. We need to act (and act before January 12th) – please read the article here.

Refs – -

Amiot, R., Wang, X., Zhou, Z., Xiaolin Wang, X., Buffetaut, E., Lécuyer, C., Ding, Z., Fluteau, F., Hibino, T., Kusuhashi, N., Mo, J., Suteethorn, V., Yuanqing Wang, Y., Xu, X. & Zhang, F. 2011. Oxygen isotopes of East Asian dinosaurs reveal exceptionally cold Early Cretaceous climates. Proceedings of the National Academy of Sciences 108, 5179-5183.

Eagle, R. A., Tütken, T., Martin, T. S., Tripati, A. K., Fricke, H. C., Connely, M., Cifelli, R. L. & Eiler, J. M. 2011. Dinosaur body temperatures determined from isotopic (C₁₃-O₁₈) ordering in fossil biominerals. Science 333, 443-445.

Farmer, C. G. & Sanders, K. 2010. Unidirectional airflow in the lungs of alligators. Science 327, 338-340.

Hone, D., Naish, D. & Cuthill, I. 2011. Does mutual sexual selection explain the evolution of head crests in pterosaurs and dinosaurs? Lethaia doi:10.1111/j.1502-3931.2011.00300.x

Martin, J., Martin-Rolland, V. & Frey, E. 1998. Not cranes or masts, but beams: the biomechanics of sauropod necks. Oryctos 1, 113-120.

Senter, P. 2007. Necks for sex: sexual selection as an explanation for sauropod dinosaur neck elongation. Journal of Zoology 271, 45-53.

Taylor, M., Hone, D., Wedel, M., & Naish, D. (2011). The long necks of sauropods did not evolve primarily through sexual selection Journal of Zoology, 285 (2), 150-161 DOI: 10.1111/j.1469-7998.2011.00824.x [free pdf]

- ., Wedel, M. J. & Naish, D. 2009. Head and neck posture in sauropod dinosaurs inferred from extant animals. Acta Palaeontologica Polonica 54, 213-220.

Yates, A. M., Wedel, M. J. & Bonnan, M. F. In press. The early evolution of postcranial skeletal pneumaticity in sauropodomorph dinosaurs. Acta Palaeontologica Polonica.

Darren Naish About the Author: Darren Naish is a science writer, technical editor and palaeozoologist (affiliated with the University of Southampton, UK). He mostly works on Cretaceous dinosaurs and pterosaurs but has an avid interest in all things tetrapod. His publications can be downloaded at darrennaish.wordpress.com. He has been blogging at Tetrapod Zoology since 2006. Check out the Tet Zoo podcast at tetzoo.com!

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The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. Jerzy New 4:33 am 01/9/2012

    Something I never imagined before – flying Velociraptor fairy.

    Link to this
  2. 2. naishd 4:38 am 01/9/2012

    If you’re referring to Luis Rey’s illustration, it’s actually a Utahraptor.

    Darren

    Link to this
  3. 3. Jerzy New 4:53 am 01/9/2012

    (it was to the right of the first picture).

    …BTW, again a thought. The idea that sauropods didn’t practice parental care means resources to produce insane numbers of eggs – thousands if not tens of thousands every year. Very, very strange ecology.

    Link to this
  4. 4. MikeTaylor 11:30 am 01/9/2012

    “The idea that sauropods didn’t practice parental care means resources to produce insane numbers of eggs – thousands if not tens of thousands every year. Very, very strange ecology.”

    Stranger than that of turtles?

    Link to this
  5. 5. llewelly 5:11 pm 01/9/2012

    “Stranger than that of turtles?”

    Wait ’till you see a picture of a sauropod basking under a red heat lamp.

    Link to this
  6. 6. Jerzy New 5:51 am 01/10/2012

    “Stranger than that of turtles?”

    Yes, considering that sauropods were like 2-3 orders of magnitude bigger and dominant animals in their habitat. So there is a risk of Mesosoic landscape be knee-deep in sauropod eggshells. ;)

    Seriously, big ecological mystery in front of paleontologists’ eyes is how any dinosaur eggs survived to hatching. Consider how vulnerable eggs and nesting parents are to predators. And sauropods, hardosaurs and ceratopsians were unable to use tactics of modern birds (short nesting season, nest in inaccessible place, camouflage nest).

    Link to this
  7. 7. David Marjanović 7:49 am 01/10/2012

    Konstruktion Morphologie

    Konstruktionsmorphologie. :-) The -s- is there specifically to bind the two parts of this word together; it’s really treated as a single word by the language, not just by the orthography.

    Naish, speaking about the ‘necks for sex’ hypothesis. Many points if you know what’s on the screen.

    Bottom: textbook illustration of the “Darwinism” part of a “Lamarckism vs. Darwinism” comparison – giraffes with too short necks simply die.
    Top right: no idea.

    And sauropods, hardosaurs and ceratopsians were unable to use tactics of modern birds (short nesting season, nest in inaccessible place, camouflage nest).

    Not quite true when it comes to inaccessible places. Remember “Egg Mountain” and “Egg Island”, the nesting sites of Maiasaura.

    The real mystery to me is how any baby sauropods survived to reach appreciable sizes. Were they capable of running after all???

    Link to this
  8. 8. DPerea 7:50 am 01/10/2012

    Jerzy, I am detecting some really strange and sloppy thinking on your part. If dinosaurs practised r-strategy style, where many many eggs are produced and small number of babies survive to adult age. where is “big ecological mystery?” This is r-strategy.

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  9. 9. Dartian 8:01 am 01/10/2012

    David:
    Top right: no idea.

    That’s probably related to Darren’s interest in the differences (or rather, the lack thereof) in bone density between giraffes and buffaloes. Dunno why Darren has the giraffe kicking the buffalo though.

    Link to this
  10. 10. Jerzy New 10:24 am 01/10/2012

    I had a weird idea, that some sauropods and hardosaurs might breed spontaneously in mass events occuring only once, for example, three or five years.

    Colonial birds rely on overwhelming predators with short excess of food. However, this strategy becomes really difficult if eggs are larger than ostriches’, sit around probably two or three months incubating, and hatchings are small and vulnerable for many further months.

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  11. 11. Jerzy New 10:36 am 01/10/2012

    Re: necks for sex:

    It would be interesting to calculate something. If large sauropod swung its neck at full speed, what speed and force would be generated at the head? And what increase of force would come from increasing neck length by 10%?

    Other than explaining headless titanosaur skeletons ;) I think neck of sauropod can be really powerful weapon.

    I saw videos of fighting male giraffes, and when one hits with the neck, another is really thrown backwards. So giraffes can generate really big force with their necks.

    Link to this
  12. 12. vdinets 11:07 am 01/10/2012

    Jerzy: large crocs can fast for up to 18 months. A specifically adapted predator could evolve to fast even longer, perhaps much longer. So to do the cicada thing, sauropods would need at least decade-long gaps between breeding seasons.

    Link to this
  13. 13. David Marjanović 11:42 am 01/10/2012

    Jerzy: large crocs can fast for up to 18 months. A specifically adapted predator could evolve to fast even longer, perhaps much longer.

    …if it had a sufficiently low resting metabolic rate.

    Besides, the most likely predators on baby sauropods were small theropods.

    Link to this
  14. 14. Heteromeles 2:02 am 01/11/2012

    Well, sauropod eggs were small relative to sauropod size, so what would be a K-strategy for an ostrich might be an r-strategy for a sauropod. There’s no reason they can’t do a masting (mass mating) strategy, especially if they only do it when climatic conditions favor the survival of young.

    Makes me wonder whether the females simply stood over their nests until the kids hatched. If they could fast long enough, it wouldn’t have been a problem. In seasonal climates,nest guarding might have even occurred during the dry season, when there was less food around for adults and babies alike.

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  15. 15. Dartian 3:52 am 01/11/2012

    A question for the sauropod experts out there: AFAWK, how many eggs did sauropods lay? Some fossil titanosaurid nests have contained 35 eggs (e.g., Chiappe et al., 2004), but are there any larger clutches known?

    Reference:
    Chiappe, L.M., Schmitt, J.G., Jackson, F.D., Garrido, A., Dingus, L. & Grellet-Tinner, G. 2004. Nest structure for sauropods: sedimentary criteria for recognition of dinosaur nesting traces. Palaios 19, 89-95.

    Link to this
  16. 16. Jerzy New 4:23 am 01/11/2012

    @Heteromeles
    “Makes me wonder whether the females simply stood over their nests until the kids hatched.”

    Basing on how sauropod nests were built – earthen mounds with eggs sticking out to the air – it seems possible they were indeed likely protected by adults, at least from elements and small egg predators. But this doesn’t solve the large predator problem.

    Lets do predator-prey population ecology it piece by piece. Suppose sauropods or hardosaurs guarding nests are common sight in Mesosoic environment. An ecological niche opens for theropods which hunt adults so conveniently tied to one spot – or eat eggs abandoned by fleeing adults. Theropod poulation grows, herbivores don’t breed at all, herbivores couldn’t exist this way.

    Colonnial birds avoid this scenario by nesting en masse within few weeks every year, and by bird colonies being relatively rare. So there is no year round food supply to support specialized predators, and a population of generalist predators, like ravens, foxes, skuas or snakes is kept low by low supply of food outside nesting season.

    But bird strategy was not possible for dinosaurs, because their breeding cycle was too long.

    @Dartian
    Sauropod nests had several tens of eggs – but it is possible that one female made many nests. Sea turtle females make several nests within space of few weeks.

    Link to this
  17. 17. David Marjanović 5:14 am 01/11/2012

    An ecological niche opens for theropods which hunt adults so conveniently tied to one spot – or eat eggs abandoned by fleeing adults.

    Both not possible. A herd of adult sauropods simply has no reason to flee and cannot be attacked if it’s not moving.

    But bird strategy was not possible for dinosaurs, because their breeding cycle was too long.

    What do you mean?

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  18. 18. Dartian 5:53 am 01/11/2012

    Jerzy:
    Sauropod nests had several tens of eggs

    I was asking for actual numbers. If you have a relevant reference, please provide it.

    (Also, I’d appreciate information on egg numbers in other sauropod clades than the titanosaurids.)

    it is possible that one female made many nests

    Yes, it is possible. But I can’t see how one could possibly show that to be the case in fossil taxa. (If we’re really pedantic about this, we must also admit that we can’t be sure that all the eggs so far discovered in fossilised dinosaur nests were really laid by just one single female.)

    Link to this
  19. 19. Heteromeles 4:42 pm 01/11/2012

    Hmmm. If you have, say, 50 large female sauropods clustered in an area (probably spread out enough that they won’t hit each other), and, say, two allosaurus wander in, what happens next? The predators are smaller than their prey, so this isn’t a good situation for the predator. Heck, even if 20 allosaurus attack, the numbers still favor the guarding females if they stand firm.

    By the way, is there a reason the experts assume that female sauropods were the smaller sex?

    The real problem females would have standing around would be pests and pathogens, and those would also be a problem once the young hatched.

    Link to this
  20. 20. Jerzy New 5:55 pm 01/11/2012

    @Heteromeles
    You imagined yourself a replay of CURRENT ecological balance – where nesting colony is a rare event.

    If a colony is around all year, what happens next? Predators gather, and breed, and gather, and breed, and grow bigger, until they overwhelm the colony.

    …maybe reading about predator-prey ecology would help.

    Link to this
  21. 21. Halbred 6:11 pm 01/11/2012

    I always imagined the sauropod situation as being basically similar to that of sea turtles: the adults dig a hole in the dirt, deposit their eggs (however THAT’S handled), then bury them and wander off. Months later, the young hatch, dig their way out, and comingle into a huge group. Most are eaten, some survive.

    I can’t IMAGINE that sauropods built nest mounds, laid eggs that were exposed, and just took off. Every predator in the area would have an immediate field day. However, once those babies start hatching, the predators STILL have a field day, but at least you get a good number of survivors.

    Link to this
  22. 22. Dartian 5:50 am 01/12/2012

    At the risk of stating what should be bloody obvious, a general comment on group living/nesting in animals (not just dinosaurs):

    Being part of a group typically decreases rather than increases predation risk for any given individual animal. There is safety in numbers in general (in many cases, even low-ranking individuals that are forced to stay at the group’s periphery are probably still better off there than they would be on their own). In addition, many species also engage in active group defence, which tends to further decrease individual predation risk; such taxa include some of the colonially breeding birds that Jerzy keeps mentioning (gulls and terns, for example).

    Thus, group living/breeding would probably have made sauropods and/or their offspring less, rather than more, vulnerable to predators.

    Halbred:
    I always imagined the sauropod situation as being basically similar to that of sea turtles: the adults dig a hole in the dirt, deposit their eggs

    But, based on what the fossil record actually shows, the numbers of eggs that individual sauropods laid may well have been substantially lower than those of sea turtles (or indeed most crocodilians). Sure, we can hypotheticise about sauropods laying hundreds or even thousands of eggs at one time, but AFAIK we don’t yet have actual evidence of them laying more than three dozen or so eggs per clutch. (Emphasis on the “AFAIK” part; I’m still hoping for an answer to the question I asked in comment #15. Mike Taylor and a couple of other exceptions aside, where are all the sauropod people who post comments over at SV-POW and the DML? Don’t they read Tet Zoo?)

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  23. 23. David Marjanović 7:00 am 01/12/2012

    (Also, I’d appreciate information on egg numbers in other sauropod clades than the titanosaurids.)

    Not known. Off the top of my head, I can’t think of any sauropod eggs that are not Late Cretaceous in age.

    By the way, is there a reason the experts assume that female sauropods were the smaller sex?

    What? That’s the first time I read any claim about sexual size dimorphism in sauropods.

    If a colony is around all year

    What makes you think it’s around all year? How long can an egg the size of a football* take till hatching?

    * Soccer ball. Not handegg.

    Link to this
  24. 24. MikeTaylor 8:20 am 01/13/2012

    Heteromeles asked: “By the way, is there a reason the experts assume that female sauropods were the smaller sex?”

    Do we?

    Well, I learn something new every day!

    Dartian asked: “I’m still hoping for an answer to the question I asked in comment #15.”

    Sorry, I don’t know much about eggs and nests. (Not even sauropod eggs and nests.)

    Dartian further asked: “Mike Taylor and a couple of other exceptions aside, where are all the sauropod people who post comments over at SV-POW and the DML? Don’t they read Tet Zoo?)”

    Although I do (usually, not always) read Tet Zoo, I have trouble following developing comment threads, because of the appalling stone-age excuse for a blogging system that SciAm insists on using instead of just installing WordPress or something else that, you know, works. In particular, Proper Blogs have a facility to notify you when there are followup comments, and I use that extensively when I am reading on Blogger or WordPress. Here? Nope.

    Link to this
  25. 25. David Marjanović 12:07 pm 01/14/2012

    the appalling stone-age excuse for a blogging system that SciAm insists on using instead of just installing WordPress or something else that, you know, works.

    What browser are you using? I had lots of trouble in IE8, but Firefox 9 works fine.

    What’s appalling is that the <blockquote> tag doesn’t work. As I keep saying, SciAm evidently didn’t anticipate that there’d be discussions on science topics.

    A “recent comments” widget like on, say, ScienceBlogs would of course help, too.

    Link to this
  26. 26. Jenny Islander 1:10 pm 01/14/2012

    Oh good, that thing where trying to see a post on this blog hangs my browser up for ten minutes is gone again.

    The Walking With Dinosaurs hypothesis of sauropod reproduction sounds plausible. For those who haven’t seen it, it’s basically “sauropods = sea turtles.” The sauropod “beach” is a place with permanent dense ground cover nearby where they all come to lay their eggs at once, burying them in the duff and abandoning them. The hatchlings all come out at once, hurrying toward the ground cover. Small predators pick off most of them. Like sea turtles, they eventually get too big for their first group of predators. At this size they are attracted to different stands of vegetation, where a whole new class of predators picks them off. The survivors find herds of adult sauropods, continue to grow to reproductive size, mate, and return to the “beaches” to bury eggs.

    But is there any evidence of what grew near, for example, that titanosaur nest site?

    Link to this
  27. 27. Jerzy New 5:10 pm 01/14/2012

    BTW, it is possible to identify eggs of individual ostriches by pattern of pores (apparently ostriches do it themselves, too).

    Link to this
  28. 28. Heteromeles 1:56 pm 01/15/2012

    Okay, I’ll go through the notes:

    @JerzyNew: Aside from that little PhD I got a few years ago in ecology, I was privileged enough to walk under a large stand of masting oaks this fall. Which, by the way, is better than reading about it in an old paper, at least in my book. Anyway, I think I suggested around #14 that sauropods didn’t nest every year, and I was assuming we were continuing that conversation.

    @MikeTaylor: As for suggesting that male sauropods are bigger, it’s good to know that every time I’ve seen that scenario on the tube has been manufactured by TV writers pulling the idea out of a random orifice, and that all suggestions of male sauropods having larger necks as a result of sexual selection aren’t taken seriously by any sauropod expert. I stand corrected. Thanks.

    Link to this
  29. 29. David Marjanović 1:03 pm 01/16/2012

    all suggestions of male sauropods having larger necks as a result of sexual selection

    It has been suggested, as mentioned above, that the long necks of sauropods are a result of sexual selection. However, there is no known sexual dimorphism in the neck length of any sauropod.

    Link to this
  30. 30. Yodelling Cyclist 7:32 am 01/24/2012

    I offer this as food for thought:

    http://www.bbc.co.uk/news/science-environment-16697954

    Link to this

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