Why was the discovery of organisms, such as archaeopteryx, that have a mix of traits usually associated with two different groups considered validation of darwin's theory of evolution?

The answer would be transitional forms like Archaeopteryx make available DNA confirmation that demonstrates how organisms are related. Transitional fossils establish the middle forms that happened over the evolutionary trail taken by a single genus. A case in point of a transitional fossil is archaeopteryx, which relates the evolution of dinosaurs (from jaws and claws) to birds (feathers).

i believe the answer is snake.

some scientists like gregory adcock agree with thorne's theory of regional continuity.

others, like chris stringer and ian tattersall, believe thorne's results may be contaminated or misinterpreted.