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BBC Horizon on Ostrom's "New" idea.



Horizon:  "Dinosaurs in Your Garden"  BBC2    8th Oct 98.

Opened with some impressive slo-mo garden birds footage. Small animals often look much more impressive this way. An added roar completed the starling’s astonishing transformation (and a blue-tit defending a pea-nut dispenser from a green finch reminded me of the Dino. Soc. UK’s treatment of me when I went to take up their invitation to help with the newsletter!) Maybe the animation artists should have looked at these and other bird films, since in this prog the "dinos. that gave rise to birds" bounced their bodies up and down far too much.

John Ostrom was the hero of the show of course. Footage of Ostrom’s team prospecting in the Rockies in the sixties made your hair stand on end – if they did it all like that I’m surprised they found anything! Norell and Chiappe were featured; their staging of conversations for the cameras . . . made me smile:

Norell: "It’ll be interesting to see if the feathers are as good as we’ve heard that they are."

Chiappe: "Yes. Especially bone-wise they’re clearly not birds." [Maybe not that clear, though it’s nice you agree with Alan on something.]

Norell: "If it’s true, it’s really going to change the way everybody thinks about these problems." [Yes, but not in the way you expect!]

Chiappe: "Well, we hope that." [So do I.]

Norell: "And it’s always nice to be back in Beijing."

Chiappe: [without much emotion] "That’s right."

Feduccia came across as highly plausible, and said such a lot I could agree with. Unfortunately his choice of dolphins and ichthyosaurs for illustrating convergence is self-defeating: "They’re superficially almost identical but when one looks at the structure in detail the similarities fall down". The similarities between birds and dinos are of a different order.

"Everything we see about feathers relates to aerodynamic function – they’re very expensive both from the standpoint of development, and structure – maintenance." He compared coating a dino with feathers to covering an ice truck with space shuttle tiles. "Gross evolutionary overkill – it really makes no sense." That is true. "In every group of living vertebrates there are examples of parachuting/gliding. In every case where a group of living vertebrates has taken to the air they have one thing in common – they evolved flight from the trees down." Also very true. Unfortunately he presumably thinks _Caudipteryx_ was not a bird, implying that feathers evolved twice. At the end he acknowledged that those with his viewpoint were outnumbered, but said that fortunately science doesn’t operate by vote. In fact, unfortunately I have repeatedly found that to a large extent it does, though through a weighted voting system – some people aren’t allowed to vote.

Ostrom claimed: "Gliders depend on a stable/immobile airfoil to support the lifting surface. Flapping flight depends on flexibility in that airfoil surface, and that’s what birds possess." This view unavoidably implies that John astonishingly does not appreciate that moving airfoils also give vertical lift to flapping birds in horizontal flight.

Another argument for "Ground up" was illustrated by the difficulty hummingbirds have when flying in low-density helium-rich air. Since there was thought to have been more oxygen in the Jurassic atmosphere, and oxygen is heavier than nitrogen, this is supposed to show flying was easier. But in any fact, the atmosphere could have been pure uranium vapour, "ground up" still wouldn’t have worked since it doesn’t explain how long arm bones, huge muscles (connected to long thin hand bones unsuitable for delivering heavy blows) and long eminently snaggable feathers could have evolved before the first benefit of flight was conferred. (The humming bird was shown through an infra-red camera in one shot, presumably to add scientific plausibility; the part of its body giving out most heat was its beak.)

The chick digit thing was covered, though as far as I’m concerned, digits behave so oddly I wouldn’t want to conclude anything from them. Besides, even if _Allosaurus_ had I, II, III, _Archae_ and the other maniraptorans could still have II, III, IV, since we have no favourite for an ancestor in the 70 million years prior to _Archae_.

Mercifully Norell’s commentary on a cladogram was fast-forwarded through, and the word was never mentioned.

As usual, Greg’s pictures were used again (_Archae._ on Ostrom's computer), while the 100% media blackout of his opinions was continued.

The Chinese site surprised me – I had expected fossils to have been found just lying around on the ground, but the site is now, at any rate, a vertical wall of strata, where small samples could simply be removed like books from a library. I find it hard to believe this is difficult to date. I thought volcanic ash was easy.

Good films, inc x-ray, of flying birds (magpies do 12 flaps per sec). It was clearly shown that the tendons or perhaps just the main tendon pulling the "hand" down also has the effect of pulling it forward. This forward movement cannot be entirely or even largely passive, caused by forward thrust from the primaries as I had thought since it starts long before the wing starts to move down. I wonder if this might have been a useful function in gliding forms even before long bristly/furry structures were replaced by proper feathers, since the characteristic carpal structure started to be developed before the appearance of feathers. Curiously, the feet seem to move backwards relative to the body during the downstroke and forwards during the upstroke – when viewed from the side; but when viewed from above the opposite appears to be the case! This is probably because one looks at different bones in the trunk in each case, and the trunk is probably rotating slightly.

We followed Our Angela round the NHM to the Archaeopteryx cupboard (so now we know exactly where to go for it!). Archaeopteryx was modelled with short and broad yet pointed wings. I wonder how pointed the wings really were. The primaries fall into that configuration in the fossil we were shown, but maybe they were characteristically more splayed in flight. I took Jeremy Rayner’s word for it that the wings are short and broad. This of course, combined with a long tail, might mean in a modern bird: tree dwelling, and dense trees at that. Or it might also mean ground dwelling, as with pheasants and road runners.  I'm tempted to say I don't know of any birds with short and broad yet pointed wings - but what about starlings?  Time to stop. 

The filmers did a good job; the palaeontologists didn't. The result was ungood, though it interested me.

JJ