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This is the post I promised, where I address all my critics at once (like at the end of "Godfather I" ?!) It’s to do with the idea of using a statistical test to decide whether "maniraptorans" existed pre-_Archaeopteryx_, who Archae’s relatives were before and especially after, and whether _A_ gave rise to the "mani’s". First, the question of why were maniraptorans so hugely successful. Is it a coincidence that their ascent started at the time of Archae? It’s often thought (and quoted) that negative evidence in the sense of the absence of something is wholly useless, but in fact it can be and is used. If we look for something and don’t find it, though we cannot say for sure it’s not there, we have to get on with life and not hang on a philosophical nicety. This happens everyday, eg where decisions are made based on the apparent absence of errors in inspected manufactured goods. (Not that there’s much at stake in saying ‘these prehistoric animals probably. . .’, and such opinions have been based on worse evidence in the past!) With this in mind, it is tempting to try to apply a probabilistic test to the conventional claim that Archae sprang from a maniraptoran of the likes of _Velociraptor_, say, particularly in view of the enormous imbalance of maniraptoran specimens pre and post Archae. Before that though we must consider the line that in my opinion *did* give rise to Archae. Clearly it will have been convergently similar to Archae itself; in fact, why should we call it anything other than a maniraptoran? Luckily, it will be distinguishable from Archae’s descendants in two significant ways: First, according to my theory it will not have feathers (since I believe feathers arose once only, at or very shortly before the appearance of Archae). Feathers alone may or may not be apparent in fossils, but they may well be inferred by considerations of skeletal remains alone. Feathered creatures will have a qualitatively different aerial capability from the furry but non-feathered (and here I depart somewhat from George’s position). Even gliding will have been well nigh impossible –orienting the body in mid air (which a furless cat could do anyway, though dragful integument would help) and the parachute effect would be the only benefits. Thrashing the air with very bristly arms (even very long quill-like bristles) would be of limited use. By contrast, the arrival of feathers (I’m skipping over the detailed explanation here – I’ve given it in full often enough in the past) would make the development of, in short, wings, possible, indeed likely. The full skeletal implications of wings, combined with feathers, distinguishes recent descendants of Archae from its immediate predecessors. There will then be some important differences between specimens pre and post _A_ (assuming its non-feathered near relatives were rapidly squeezed out) and I suspect flight very strongly enhanced its descendants’ evolutionary success, whether through through metabolic, neurological, cursorial or simply distributive enhancements (amongst many other possibilities). It is through these differences that I believe a useful probabilistic test of some kind might be made. Something ‘very maniraptoran’ did exist - it had to, to give rise to Archae. However I predict that none of the types found in the K will be found pre Archae. Archae’s close ancestors will have been spinning off larger, non-arboreal forms presumably, in the way George has described, and some of these will be found. Perhaps the specimen Tom describes as maniraptoran was one of these (though notice, it has not been possible to say for certain exactly which type it belonged to – ‘probably troodont hips/legs’ I believe). These creatures that follow Georges description I describe as ‘Olshevskyan’: arboreal, spinning off the odd cursorial form, yet ‘not quite there’ due to their reliance on whatever came before proper feathers in the full aerodynamic sense. It is these that will be found pre-Archae, *not the specific maniraptorans of the K*, and maybe this could be the basis of a statistical test. But as I hinted when I first suggested it, it might take years to formulate the test, and compare it with similar examples. I don’t envision taking the idea any further myself, and I don’t think my discussing it further on the list would do much good. Some confusion arose concerning exactly which forms I meant by maniraptoran, and exactly which I considered to be descended from _A_. I chose "Maniraptoran" because I thought it might include all those I saw as _A_-descendants, but they didn’t quite fit. The definition of various groups I took from TM Keesey’s website ###### ("Coelurosauria" page) but as it’s not my tree I’m not going to defend its merits (though the site is excellent!). Eventually I had to state all those creatures I thought were descended from _A_. No other person’s tree includes this group exactly, so I also had to name the group since there was already a lot of confusion. (I ‘wanted’ particular types in the group because, for whatever reason, I believed they were descended from _A_, and not because I sell magic pyramids, or believe the world will end on Thursday (though I suspect it will for some theory or other, if it’s as big a revelation as people suggest!)) This clade will consist of creatures with feathers or feathered ancestors. I’m going to call its members "Pinnants", though for absurd and iniquitous reasons I would be prevented from publishing it "formally". I’m fully aware of the disgraceful situation, I can assure you, and I’m not going to be gagged by it. Don’t bother to complain – I’m going to carry on using Pinnants, and if I get thrown off the list because of it, then you’re all PATHETIC! What you should be doing is pressing for the odd small but significant change to the peer review system. ("Birds" would be a better name, but it’s too confusing.) Of course, all this rather depends on whether my theory of feathers is right, so if it’s of any comfort, you can regard it as a hypothetical clade. Inside Pinnants, I see at least three new clades, probably all sisters, though I don’t as yet have any idea of exactly what went on just after the "Big Bang": The first clade is Uncinants. I consider uncinate processes to be rather a stable feature within theropods. They do and probably always did have their own centre of ossification. This is why they often fall off fossils. For theropods, they are IMO sure signs of flying ancestry. Currently droms, ovi’s, and moderns are within the Uncinants. I would be interested to know if anyone is certain of this char. w.r.t _Protarch/Caudipteryx_. Enants are another clade of course, and I’m fairly happy to have tyrannos/troodonts/ornithomimids (aka arctometatarsalians) as a third. _Pelecannimimus_ looking so birdlike helps a lot. Feathers would be lost from multiton carnivores as they would be rubbed off against the ground or large prey. I took great care not to follow the discussions of alvarezsaurids a few months ago, but I believe some wanted them in the arctos, though others saw them as too birdy. Would making arctos "birds" help ? My discussion with Matt seems to revolve around whether loads of skull features only present in flightless forms can be simultaneously reversible with loss of flight. I say it may well be such a suite, (along with chest and arm stuff) and that presence of uncinate processes and to a lesser extent direction of pubis are more stable characters. Tom said: >A ) Hooking and pulling is EXACTLY the type of "killing blow"
proposed for < Why did eg _Deinonychus_ need relatively much longer and more powerful arms for catching its prey than say _Allosaurus_? And why did it need its shoulder joints so much nearer the backbone? (And why the backward pointing pubis and the stiff tail?) The arms are very powerful – too powerful for just holding the prey back. Not just powerful enough to climb up onto the prey, in fact, if you compare the muscle attachment flanges on the humerus for _D_ with a human, who may be able to pull himself up by his arms alone, there is an enormous extra capacity. Useful for climbing on prey, but why did it evolve this enormous overcapacity in the first place? They use the phrase *killing blow* but you say *other parts* would dispatch the prey. Either you disagree with them, or there would seem to some uncertainty in their minds. What I think the animal really did was climb on much bigger prey, press down with the big foot claws, and pull up on the prey with the hand claws. The arms/hands were used in both climbing and in opposition to the feet. The impression I got from the Sci Am Feb 98 article was that the hand was supposed to be used for killing, at least in the early stages of its evolution, and this explained the extra capacity. I don’t think you agree with that, and I don’t either. I still believe _D_’s whole suite of specialisations are best explained by climbing trees, flying, and exaption for predation. >B) Sorry, the material that Jensen and Padian describe is quite
clearly < As I mentioned above, it may appear to be in Archae’s line somewhere, but the important distinction is "pre or post", because this would have bearing on whther the K mani’s were ex-_A_. However, *this* is really the paper I want to see.
JJ When it comes to "madness campaigns" – do you think I’m safe? |