Neck multifunctionality

Following on from my post on sauropod neck lengths (and indeed that of the SV-POW! boys and Tet Zoo too), at the end I made the inevitable comment that necks (and indeed other structures) can be multifunctional. A long neck can be an indicator of sexual selection at the same time as providing increased reach for food. As noted before, analogy plays an important role in working out (or at least hypothesising) palaeo behaviour, so are there any animals out there that seem to do this. Indeed there are, so step forward, the Galapagos giant tortoise.

Tortoise neck use - above, reaching for food, below, challenging rivals. By Darren Naish, from Taylor et al., 2011.

Research shows that those animals with longer necks do gain a distinct advantage in reaching higher placed food. The neck provides a genuine basis for natural selection based on neck length. However, it has also been shown that when tortoises stand off in dominance battles, the individual with the longer neck tends to win. So, necks would also appear to be under some measure of sexual selection / dominance as well.

So what about the giraffes? They have long necks and the males fight with their heads, so what’s going on there. Well males do have longer necks than females, but there’s not really anything to say that longer necked males do better. Bigger males do better (no surprise) but not through a longer neck per se. Plus of course the males are actively fighting with their heads. (And tortoises can be quite vicious if you’ve ever seen them fight, then bite and butt with their shells).

Posturing only gets you so far in nature. Sure, there are cheats out there (false cleaner fish, milk snakes, female mimic salmon etc.), but they can only prosper as long as they are in the minority. This is because sooner or later someone is going to square up to you in one way or another and find out if you really can back the bark with bite. If you can’t, you’re going to lose. And if say most of the population were lying, once a dominant animal (or predator etc.) finds out, then that is going to take over damned fast. So lying only works when there are few liars, and most things are honest. In other words, if they are advertising that they can win a fight, it’s because they can and will.

What does this mean for sauropods? Well is has been suggested in the past that sauropods might fight one another, with their necks. Now if this was going to happen you’d expect to see some evidence of this in sauropods. Like the especially tough and thick skulls of male giraffe, or the prow-shaped rams of some tortoises, or robust necks and heads in male sauropods and you’d see injuries from some serious sauropod neck-on-neck action. Only of course there aren’t any.

Instead sauropod skulls are incredibly weak and fall apart if you look at them funny, let alone ram them into something else at speed. And while the neck as a single unit might be quite tough, it has those lovely wafer-like lamina and those oh-so-thin cervical ribs. If they were fighting we’d see breaks, pathologies, healed bones and the rest. And you can’t cheat by just having a big neck and expecting the others to back down, you have to back that up or someone will realise it’s all talk.

I’m sure sauropods did fight on occasion, sooner or later animals of pretty much any species will come into competition and of course it is members of the same species that tend towards the fiercest competition. There will come times when accessing that water hole, or harem, or territory is critical and combat becomes inevitable. But was it with the neck? No. The neck might have been a *symbol* of the power of the individual even if it wasn’t used (pheasants and cockerels show off their colours to demonstrate their fitness, but they fight with their spurs).

3 Responses to “Neck multifunctionality”

  1. 1 Josephine 19/05/2011 at 10:52 am

    “…sauropod skulls are incredibly weak and fall apart if you look at them funny…”

    First of all, that is a very illustrative sentence!
    Second, is this the reason for why sauropod skulls have a habit to be missing from fossils? Or is another reason to blame?

    • 2 David Hone 19/05/2011 at 10:59 am

      Well its’ probably a very large part of it. They are made of very thin bits of bone and so are going to be very vulnerable to being broken, eroded, or just not preserved.

  2. 3 Mark Robinson 21/05/2011 at 3:53 am

    Ah, so that’s why so many sauropod fossils are missing the skull. They’re the combat losers who have had their head smashed off their necks by a rival! And Shunosaurus’ tail club was a false head used to deceive rivals into attacking the wrong end.

    Sauropods – inventors of the game of conkers.

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