In 1869 Thomas Huxley proposed the theory that birds descended from dinosaurs. For a long time, however, the idea was widely unaccepted and it wasn't until the discovery of many specimens of feathered theropod dinosaurs such as Archaeopteryx and other like it which lived in the late Jurassic and thereafter that pushed the idea into the spotlight and allowed it to gain traction and support. The idea is now widely accepted and new fossil finds are providing insight into how small flightless feathered raptors became the incredibly diverse array of birds that share the Earth with us today.
Comments
Perfect paragraph comment
A revsion that I would suggest would be to make the second sentence not so long. One way to do this would be to end it after the word "Jurassic" and start a new sentence there. Also the word other should be changes to others. The detail and wording in the paragraph is very good, I just feel as though it could be broken up better.
PP comment
You are missing a couple of commas here and there, but I think you have used good scientific notation to get your point across to the readers. I would have possibly given maybe one more piece of evidence as to how scientists were able to establish the link between birds and dinosaurs, or provide a little bit more detail regarding their findings.
Theory
Theory has a particular meaning as a scientific term, refering to long-accepted scientific understanding, rather than conjecture or hypothesis. If you're "proposing" something, you're not proposing a theory.