My longtime friend and colleague Gareth Dyke has a new paper out this week on the feathers of early birds and the implications for flight. In short ths shaft (rachis) of soem of the flight feathers are a bit weak. He’s kindly (or foolishly) agreed to provide this little post on the origins of the paper:
When I was living in BC, Canada, I got talking to my friend Gary Kaiser, a retired marine ornithologist from the Canadian Wildlife Service. Gary had noticed – and published in his Inner Bird book (2007) – that compared to the overall wing length, the primary feathers of Confuciusornis are extremely long. Much longer in fact than any living bird. So, we started to work on this problem: how could a bird with such long primary feathers flap it’s wings.
This led Rob Nudds (University of Manchester) and I to the issue of the rachis diameter of bird primary feathers. One day in Dublin in 2009 we were sitting in the pub (as we often do: Rob loves to drink Beamish – a stout from Cork that is hard to buy in Dublin … this involves lots of walking around and checking taps in pubs as most, of course, sell Guinness) thinking about flapping in fossil birds. Based on this conversation, I went to Munich and Frankfurt later that year and made some measurements – the rest is in the paper.
Archaeopteryx has shorter feathers relative to the rest of it’s wing – still quite long (but within the range of living birds) – but has an extremely thin rachis. The simple modelling we have done, assuming similar keratin properties in fossil bird feathers and living feathers, shows quite clearly I think that the feathers of Archaeopteryx and Confuciusornis must have been structurally weaker than those of living birds. People will argue with the approach, and of course lots of palaeobiologists and biomechanists have lots invested in the flapping flight of Archaeopteryx in particular – it’s funny though that no-one has really examined the strength of the feathers of these bird before.
Finally, although we didn’t say this in the paper, I think that this analysis combined with our 2009 Evolution paper shows that the wing-assisted-incline-running (WAIR) hypothesis for the origin of bird flight cannot be correct … (but that’s the subject of another blog).
Nudds, R.L. and Dyke, G.J. 2009. Forelimb posture in dinosaurs and the evolution of the avian flapping flight-stroke. Evolution 63(4): 994-1002.