 While it is unknown when "Synemporion" first arrived in the Hawaiian islands, the oldest known fossils are from 320,000–400,000-year-old deposits on Oahu.One bone from another site on Oahu has been dated at 2718–2479 years ago, but some undated remains indicate that "S. keana" survived until more recently; relatively well-preserved skeletons in a wet, dynamically active cave on Molokai suggest that the bat may have survived until as recently as a few thousand years ago.Like many Hawaiian birds, the extinction of "Synemporion keana" may have been caused by humans, either directly or indirectly.