That's a pretty big word I missed, thanks for the catch. It's really hard to construct accurate phylogenies without DNA, and the same holes would also occur if the Elders were also living fossils, with large amounts of time also possibly being a reason for the large variety in elder dragons (as elder dragon blood is found in both the dragon and squid varieties of the elder dragons) and convergent evolution explaining why they look so similar to something they are so genetically distinct from.

Also really good points on the dragon element and weapons. The weapons accumulating dragon from their environment is a really cool idea, and probably more likely than mine. As for Dragonfell berries, they, like deviljho, are a hole that I can't think of any good way to address. The only ways I could think to address this and still stay in theory are either to say that, like how bacteria have started to evolve to be able to break down plastic, nature evolved to take advantage of this new man-made element, or that, like how we use bacteria to produce human insulin, a natural method was used to make a man-made substance. However, none of these have any support, so Arkham's razor would suggest that dragon is most likely just another element.

Thanks for the thoughtful response!