As far as it is known from the history of embryology, little was known about the staging and classification of human embryos until the twentieth century.

就胚胎学的历史而言，在20世纪之前，人们对人类胚胎的发育阶段和分类都知知甚少。

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"They give us an unprecedented look into the very early embryology of these developing dinosaurs, " said paleontologist Mark Norell at the American Museum of Natural History in New York, who wasn't involved in the find.

WSJ: Dinosaur Embryos Point to Rapid Growth