What a mess.
To understand the evolution of a group of animals you need a good family tree, and good trees can be made from analysing DNA in fossils that preserve it. But because evolutionary convergence and reversal appear more in bone shapes than in DNA, Brussatte’s reliance on bone shapes gives wrong family trees. We KNOW this happens: we saw it in the different mammal trees that DNA and bone shapes gave. Brussatte ignores this, having no qualifications or background of any work in the computer science of generating these trees, and being a superb follower of whatever he thinks will go down well with “the group”. What he does fail to follow is any sound hypothetico-deductivism in his work: he never shows any appreciation that backtracking is necessary in theorisation and seems to think that science hops from one fact to another. Even if perfect facts were real they’d be created out of hypotheses; treating every idea as a fact from the start is pseudo science, and could never survive if errors in palaeontology were lethal.
He understands that palaeontology is run as a social game where any CHANGE in an old view is wrong (as it would be if it we had facts instead of having to rely on theories), and because it would annoy those who fear change.
So when he says bird evolution appears to depart from the normal idea of evolution (which he has got right): “a species develops a feature that allows it to do something better; its offspring also express that feature…” and so on till an early minor ability fully develops, and he claims bird flight didn’t do this, he is working from the wrong family trees, and he cannot change his mind.
However a much better real family tree would be distorted by parallelisms and reversals so it would actually resemble the computer-generated trees Brussatte trusts! But he hasn’t the brains to see thus subtlety nor the integrity to respond to it if he did.
In fact the sensible family tree DOES progress nicely from early gliding forms to later flapping ones, many of which lost the power of flight just like ostriches did – so his comment on one site that the ostrich mimic dinosaurs couldn’t have evolved wings for flight as they couldn’t have flown with them is ridiculous. His claim that “anatomical analysis suggests such a development likely had nothing to do with flying” comes from analyses of creatures living long after the first fliers and so had nothing to do with the earliest fight, and the study he emphasises most (Dececchi et al. 2016) refused even to CONSIDER the possibility that flight evolved from gliding! (as well as using wrong trees).
And yet, despite hating the idea of gliding as a precursor to powered flight, gliding is the only possibility the studies consider in the case of Microraptor! They never consider the obvious likelihood that it could even flap its front wings never mind its rear ones!! Yet they both have all they need to flap! The flight-perfect primaries on the rear feet even get in the way of walking! Why does Brussatte think those feathers survived there?!
They’re actually asking us to believe flight evolved by running along the ground flapping, and then decayed into just gliding in several forms perfectly adapted to flapping. He uses the evidence for colour in fossil feathers as evidence against their evolution for flight. Do modern birds with coloured feathers not use them for flight? Lunacy.
Brussatte’s work is the kind of scientific fraud that comes from a field – palaeontology – which recruits only those who have no expertise in any skills useful in it, and science administrators who know nothing about the philosophy of science. The inventor of a fake bomb detector got jailed, you may recall. Brussatte and so many others would be jailed if bad palaeontology cost lives.