They are believed to be descended from Amaurornis-like ancestral stock.

His status as a member of the ancestral stock, he found, served him as well as a sword in most encounters with strangers.

What about their wild ancestral stock?

This innate knowledge was something Chilaili had long suspected the Tersae shared with their ancestral stock.

When I asked Senator to test the neurotoxin on tissue from live, uninfected ancestral stock, the stuff invaded within seconds.

"That's the one they used as ancestral stock then."

His craggy features were as alien in their way to the ancestral Terran stock of the others as that blue-tinted skin.

In short, the circumscription s.s. includes all and only plants that have descended from that particular ancestral stock.

Further analysis suggested that this particular species diverged from its ancestral stock some 5.7 million years past.

Posthumans, spending so much of their time in microgravity environments, were significantly less robust than their ancestral stock.