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Stegosauria morphogenesis of groups
When Willis O'Brien struggled for days, in 1932, with his stegosaur puppet (he had originally, as he would do with the tyrannosaur, posed it with tail erect, legs more columnar, but found it "aesthetically" not acceptable, viz. he had the correct idea of posture but opted for H.F. Osborn's mind sets), he wanted to have more than one animal on the animation. RKO budgetary restraints meant one animal, with 8 spikes on its tail. Would several stegosaurs have attacked the S.S. Venture's sailors, or would they have ignored the hominids? We shall never know...the scene ends with the echo of gunfire in the unconscious animal's face.
But the question has interest for me. It is possible that there was some kind of division of labour among stegosaurs. I can't imagine them spending hours just walking, eating, without social lives. Division of labour entails several explanations in recent research: group, "self gene", individual adaptations, self-organization principles (favoured theoretically by Stuart Kauffman et al.), hormonal regulatory paradigms so that, with increased age, the "labour" changes within a group. Perhaps, paleontology should breath life, as it were, into the bones. We could have, in studying stegosaurs, vertical insights (gene > cell > organism > stegosaur herd), or horizontal phylogenetic systematics (evolutionary origins + form-function consequences + ontogenesis + mechanisms of locomotion/eating/mating). Reductionism in studying stegosaurs is, as yet, not useful (did they travel in pairs, or in larger groups, because of "selfish genes"?), but, then, neither is compositional!
y (different questions, different answers). For example, I have seen all of the mounted stegosaurs in North American museums: majestic, lone skeletons reflected on well-polished floors, overhead lights not quite being substitutes for a Jurassic sun (or moon)...with little or no indication of their ecologies. Has anyone gone back to field records to determine what fossil plants were found with the skeletons? Location of nutrient foliage, at different times and locations, presupposes some kind of memory among the animals for the appearance of such food supplies. This is, in essence, a recombination frequency of behaviour, adaptive traits (the animals divided labour, including remembering; were resistant to parasites and pathogens; and the traits probably played a role in sex determinations). And, if these were not adaptive traits among stegosaurs, were they artifacts? If such behaviour is/was adaptive, then proximate mechanisms were involved in stegosaur evolution: recom!
nations translated into "higher" fitness levels. Turning to living dinosaurs, or to any other living vertebrate, one quickly learns there is an illusion among some "phylocodes", the idea that numerous genes, somehow, with small effects are the foundations for quantitative social traits, that gene + gene interactivity is cumulative, that epistasis can be ignored. Quantitative genetics can never provide one with the methodological tools for watching how genomes change and evolve.
Thus, I have yet another question re: our stegosaurs. Did their hypervariation appear in response to selective pressures (larger, faster predators) on their communication systems, or did the various armour patterns of stegosaurs appear for other reasons but were, so to speak, coopted as recognition signals? It could be that selective processes of evolution of the stegosaurs acted on their ability of see variation rather than on variation of the signals.