“placental mammals”造句，怎麼用placental mammals造句

"Chorion:The outer membrane enclosing the embryo in reptiles, birds, and mammals. In placental mammals it contributes to the development of the placenta."

But the syncytin genes we use today may have actually replaced an ancestral one that a virus bequeathed to the very first placental mammals.

A plausible reason is that all the dinosaurs had been killed off, except the line that evolved into birds, and the placental mammals speciated into the ecological niches that had been left vacant.

all mammals except monotremes and marsupials are placental mammals.

Of or belonging to the infraclass Eutheria, a division of mammals to which all the placental mammals belong.

(embryology) the organic process whereby a fertilized egg becomes implanted in the lining of the uterus of placental mammals.

monotremes and marsupials are aplacental mammals.

young of various large placental mammals e.g. whale or giraffe or elephant or buffalo.

The modified blastula that is characteristic of placental mammals.

“The fossil record continues to show that the origin of modern placental mammals postdates or is at the Cretaceous-Paleogene boundary, ” he said.