Fossil pelvises suggest brooding might have evolved late in modern birds. Fossil pelvises suggest brooding might have evolved late in modern birds.

中文翻译：

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早起的鸟儿可能太重了，不能坐在鸡蛋上

化石骨盆表明育雏可能在现代鸟类中进化较晚。化石骨盆表明育雏可能在现代鸟类中进化较晚。