Passage Summary: Some scientists think birds evolved from dromeosaurs because they look similar, but an expert says this is impossible because birds appear in the fossil record much earlier than those dinosaurs do.

Conclusion: The theory that birds are descendants of dromeosaurs is incorrect.

Reasoning: The fossil record shows that the earliest known birds existed tens of millions of years before the earliest known dromeosaurs.

Analysis: The expert's logic hinges entirely on the timeline provided by the fossil record. For the conclusion to hold, the expert must assume that the oldest fossils we have found actually represent the true chronological beginning of these species. If dromeosaurs actually existed much earlier than our current fossils suggest, the expert's 'fatal flaw' disappears. Look for an answer that bridges this gap by assuming the fossil record isn't missing millions of years of dromeosaur history.