Boundary clay layers are used by scientists to determine the rate at which an extinct species declined.

边界粘土层被科学家用来确定一个灭绝物种衰落的速度。

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An extinct species or race of human beings, Homo neanderthalensis, associated with Middle Paleolithic tools.

作为已灭绝物种或人类种族，尼安德特人与旧石器时代中期的工具有关。

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This is an extinct species of fish.

这是一种已经灭绝的鱼。

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But for these vigorous conservation measures, the unlimited-liability names might well be an extinct species already.

ECONOMIST: The Lloyd's insurance market

How many philanthropists get an extinct species of their very own?

WSJ: How Dallas Does Philanthropy: Perot Museum of Nature and Science

Palaeogeneticists at the University of Copenhagen and Michael Bunce at Murdoch University in Perth, Australia determined the half-life after studying a set of 158 DNA-containing bones from an extinct species of bird called "moa" (a feat in and of itself).

ENGADGET: Alt-week 10.13.12: is the Universe a simulation, cloning dinosaurs and singing mice