What is an "endling?"

An endling is a new name for an individual that is the last of its species.  I suppose we needed a name, depressing though that is.  Coined by a medical doctor who campaigned for it in scientific literature, the word is catching on.  I have written about way too many endlings, like Martha the passenger pigeon, whom I saw at the Smithsonian, and Benjamin the thylacine, who was famous as an endling but probably was NOT the endling of his species, which adds a layer of controversy to the the whole business,