Why the long necks? Probably not sexual selection
May 16, 2011
Thanks to everyone who joined in the discussion last time on why sauropods had such long necks. I’ve discussed this a little with Matt, and we are both amazed that so many different hypotheses have been advanced (even if some of them are tongue-in-cheek). We’ll probably come back to all these ideas later.
But today, we want to draw your attention to a new contribution to this discussion — a paper in the Journal of Zoology, with the tell-it-like-it-is title “The long necks of sauropods did not evolve primarily through sexual selection”, written by the three of us SV-POW!er rangers together with our buddy Dave “Archosaur Musings” Hone (Taylor et al. 2011).
This is one of those papers that has been literally years in the making, which is why it’s a rather belated response to the paper that we were responding to — Phil Senter’s (2006) argument that sexual selection was the primary driver of neck elongation in sauropods.
Senter supported his hypothesis by laying out six predictions which he argued should be true for sexually selected necks; then showing that, while the first two could not be assessed, the last four all supported sexual selection. In our paper, we do three things. First, we make the point that sexual selection and feeding advantage are not mutually exclusive. Second, we revisit all six predictions and show that they do not in fact support sexual selection — in fact, most of them provide support for feeding advantage. Finally, we show that no tetrapod clade comparable with Sauropoda has consistently selected for a single sexual signal.
My email records show that Darren, Matt and I were discussing this as early as 22 September 2006, just six weeks after Senter’s paper was published, and that we started working on a response only a couple of days later. But as so often happens, it got crowded out by a hundred other things. Then in November 2007 Dave Hone mentioned that he was independently thinking of writing a response, and we decided to join forces. And then … we all went back to working on other things again, touching on the necks-for-sex issue every now and then. It’s mostly due to Dave’s repeated prods that this project wasn’t allowed to wither away, and has now, finally, made it across the finish line.
Like the neck-posture paper (Taylor et al. 2009), this was a true collaboration — one of those where, for many parts of the text, none of us is sure which of us originally wrote it. It went through the wringer many times before reaching its final form, and most of the text must have been rewritten two or three times along the way. We hope all the shuffling and polishing has resulted in a paper that reads straightforwardly and even seems obvious. “When something can be read without effort, great effort has gone into its writing” — Enrique Jardiel Poncela. That’s the goal, anyway.
The paper itself is available at the link below, so take a look and see whether you find our argument convincing. As always, comments are open!
Update (the next morning)
Co-author Dave Hone discusses this paper on his own blog.
- Senter, Phil. 2006. Necks for sex: sexual selection as an explanation for sauropod dinosaur neck elongation. Journal of Zoology 271(1):45-53. doi:10.1111/j.1469-7998.2006.00197.x
- Taylor, Michael P., Mathew J. Wedel and Darren Naish. 2009. Head and neck posture in sauropod dinosaurs inferred from extant animals. Acta Palaeontologica Polonica 54(2): 213-220.
- Taylor, Michael P., David W. E. Hone, Mathew J. Wedel and Darren Naish. 2011. The long necks of sauropods did not evolve primarily through sexual selection. Journal of Zoology, Early View (Online Version of Record published before inclusion in an issue). doi: 10.1111/j.1469-7998.2011.00824.x