Question: who are believed to be the direct ancestors to birds
[{'answer': 'theropod dinosaurs', 'provenance': [{'wikipedia_id': '6763404', 'title': 'Origin of birds', 'start_paragraph_id': 1, 'start_character': 192, 'end_paragraph_id': 1, 'end_character': 210, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '6763404', 'title': 'Origin of birds', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 250, 'bleu_score': 0.9076141716697391, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 279056505594536218}, 'section': 'Section::::Abstract.'}]}]