The zero point of the density scale is defined by having no specimen in the densitometer.

定义密度计内没有样品时的密度为密度尺标的零点。

youdao

Dr Currie said it was hard to say how long the biggest specimen was because no complete skeleton had been found.

BBC: NEWS | Science/Nature | Dino may have been pack hunter

Dr. Bour quickly concluded that the specimen came from Brazil, not Aldabra, and that gigantea was therefore no longer a valid name.

WSJ