The smallest unit of DNA was the clue. I ended up backing into the word. The dictionary definition includes a little more information, though.
muton: n. The smallest unit of DNA at which a mutation can occur; a nucleotide.
An ostrich-like bird? It ended up as “maa”. The definitions I found were not quite consistent with the clue, though. An abbreviation for Master-At-Arms; an ethnolinguistic group in Vietnam; macroaggregated albumin (???); and a common European gull. Unless European gulls are significantly larger than their American cousins, the “ostrich” clue seems a bit off.
Pali’s clue was a Sanskrit dialect. More specifically,
a dialect descended from Sanskrit, and like that, a dead language, except when used as the sacred language of the Buddhist religion in Farther India, etc.
Who knew that an echidna was an egg-laying mammal? Not I. Here’s a more precise definition:
Either of two nocturnal, burrowing, egg-laying mammals of the genera Tachyglossus and Zaglossus of Australia, Tasmania, and New Guinea, having a spiny coat, slender snout, and an extensible sticky tongue used for catching insects. Also called spiny anteater.
Shuffling through a book-less desert 
Coming to Australasia would help you with your crosswords! The Echidna and the Duck-Billed Platypus are both from Australia and we all know about them! There’s also Long-beaked Echidna recently “re-discovered” in PNG.As for your “Maa” – you should try “Moa” instead – it was a large flightless bird bigger (like an Ostrich but slow moving) resident to New Zealand. Unfortunately hunted to extinction. Although a pub in Arthurs Pass swears there is one still wandering around – like Nessy!
Moa makes better sense…but that means my other answers were wrong. Uh oh.Australia is on my list of places to visit, along with NZ and Pacific Islands. Sadly, I must intersperse travel with work, since I haven’t figured out how to be paid for my travels 😉