Question: when did the first birds appear in the fossil record
[{'answer': 'late 19th century', 'provenance': [{'wikipedia_id': '4577602', 'title': 'Evolution of birds', 'start_paragraph_id': 10, 'start_character': 144, 'end_paragraph_id': 10, 'end_character': 161, 'bleu_score': 1.0, 'section': 'Section::::Mesozoic birds.\n'}]}, {'provenance': [{'wikipedia_id': '4577602', 'title': 'Evolution of birds', 'start_paragraph_id': 10, 'start_character': 0, 'end_paragraph_id': 10, 'end_character': 904, 'bleu_score': 0.986797956037998, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7758705364605878545}, 'section': 'Section::::Mesozoic birds.\n'}]}]