1) Middle Jurassic extinction
Found on
https://www.crosswordclues.com/clue/microconchida
The Order Microconchida is a group of small, spirally-coiled, encrusting fossil `worm` tubes found from the Upper Ordovician to the Middle Jurassic (Bathonian) around the world. They have lamellar calcitic shells, usually with pseudopunctae or punctae and a bulb-like origin. Many were long misidentified as the polychaete annelid Spirorbis until .....
Found on
http://en.wikipedia.org/wiki/Microconchida
No exact match found.
