How much U-236 was in this extracted item? Was it in ratio to U-238, or free? Did they do any trace analysis to see it it matched the signatures of European nuclear reactors? What level of investigation proceeded from “we detect U-236”?
Because your source for the abundance of U-236 describes using those tracers to measure sources of the U-236 for potentially tracking contamination from specific reactors.
A more logical conclusion is that there was some testing error, or that it was made up to enhance his argument about extraterrestrial source, or he misintrepreted some information, or…
“Right, because convergent/ parallel evolution shows that similar environments create similar functional needs, and thus similar appearances.”
Why 4 limbs? Why not 6, or 8? Why upright walking and not scampering on 4 with another 4 of a different shape for grasping, the way spiders or lobsters have differing appendages?
Why a soft, smooth skin, rather than fur or scales or a completely new form of dermal armor?
Why teeth, layed out in a semicurcular curve at the bottom of the face? Why not a beak set in the middle of the torso?
Yes, a only have a dataset of one planet, and one chain of evolution, but even that one dataset has a great deal of diversity, branches with hundreds of different directions and shapes.
But like you said, why one one set of knees that bend one direction instead of the other? Just because the being would need some sort of appendages to manipulate tools hardly justifies they need to look like hands, with specific thumbs.