Herbert L Cooper's "A Nice Little Niche" (short story, ecology, free): When vitamin K craving alien bacteria infected human guts

Someone thinks the author might be a pseudonym of Edmond Cooper, based on the story style. And as far as I can find, this is the only published story of "Herbert L Cooper", a story that has never been reprinted.

Story summary.

This is a classic Campbell puzzle story. Human explorers have arrived on a very desirable world. Only there is evidence that there once were mammalian animals here that died out a few hundred thousand years ago.

A doctor on board will puzzle things out, & barely save the humans on board...

Fact sheet.

First published: Astounding, March 1956.
Download full text as part of the scans of Astounding (British edition), August 1956.
Rating: B.
Among the stories from Astounding/Analog issues edited by John Campbell.