Look at Dem Webby Li'l Arms

Added: 2026-05-26

[00:00:00]Dinosaurs using feathers to fly is unique. Other vertebrates that fly or parachute or glide use membranes of skin, pitia. Birds have patia, too, but it's hard to see them under the feathers, which is why I was excited when Superreal sent us this toy, which is a plucked version of their donicus and actually shows the propetium running from shoulder to wrist. This and other patriia that birds have aren't directly part of the air foil. They are a plant intermediary between the bone and the muscle inside and the feather surface.

[00:00:36]It's an extra step that wouldn't evolve unless feathers were aerodynamic or close to it before the webbing started spreading out. But one ornithologist, Penny Cookook, imagined what it would look like if things were the other way around. In a chapter with the excellent title past the squirrel barrier, Pennyuk hypothesized an archaeopteric precursor with patia forming the entire wing stretched across its fingers like a bat with simple scale-like feathers along the trailing edge. In his scenario, the webbing would have been given way and reduced as the feathers with quills and veins took over aerodynamic duties. Even though he was writing in 2008, Penny Cook doesn't seem to have meaningfully revised his bat archaeopric idea since the 80s. He's ignoring mountains of evidence that have come out in the '9s and 2000s about the evolution and relationships of the therapods closest to birds, including the development of feathers, which he had basically backwards, and the fact that none of these animals had their handbones fanned out in bat fashion. But then a funny thing happened. Also in 2008 we have the description of Epidexipterix a scansopter theropod. This is an odd group of little tree climbing therapods.

[00:01:50]Hence the name slightly older than archopterics. Their arms are remarkably winglike but they completely lack penacious flight feathers. All they have are simple filaments, these little tufts and these long ribbon-like tail ornaments. One therapod worker cow speculated that this combination of features would make sense if scansopterids like epidexterics had a memberous wing stretched across those long fingers and they did. We have since discovered two scansopterids with wings ambopter longabrachium and ichi.

[00:02:28]Finally, one of these has a short name.

[00:02:30]We don't have to make up hypothetical bird ancestors out of whole cloth. We only have to recognize that penoraptor evolution produced many experiments and birds are only one of them.