Did they determine this by comparing what DNA fragments they’ve managed to recover, or by physical skeletal structure similarities, or what?
I’m no expert in the field, but I just don’t see it.
i think a better way to look at it is; the chicken and the t-rex share a common ancestor
an animal existed that branched into 2 different paths, one towards birds and the other big ol lizard things (conjecture, am stupid)
This is exactly right. T-Rex is a Therapod. Another line of Therapods turned into birds. That line of Therapods is called Dromeasaurs.
https://en.m.wikipedia.org/wiki/Dromaeosauridae
Also (maybe more accurately) https://en.m.wikipedia.org/wiki/Paraves
Over the last 15 years, scientists have updated the theorized appearance of thousands of species of dinosaurs to have feathers. Most of these species are in the theropod family. You’ll be seeing updates in natural history museums as time goes on.
https://www.amnh.org/exhibitions/dinosaurs-among-us/feathers
There’s also the chicken’s talons to consider. Birds with similar claws are called raptors due to their similarity in appearance to the dinosaur. This does not mean they are direct descendants, however, but that they have a genealogically shared ancestor.