So it turns out that a mysterious bat skeleton found in a Maui cave way back in 1981 is actually a rare mammal species endemic to Hawaii that appears to have gone extinct shortly after human beings arrived in the islands. In biological terms, this is huge news.
“This finding is not only significant in that it shows we had a higher diversity of land mammals than was previously known, but also shows the significance of researching Hawaii’s lava tube fauna in giving us a glimpse into what was living in Hawaii thousands of years ago,” Bishop Museum researcher Neal Evanhuis said in a Mar. 22 news release from the museum.
“The Hawaiian Islands have long been thought to support just one endemic land mammal in its brief geologic history, the Hawaiian hoary bat,” states the news release. “New fossil evidence indicates that a second, very different species of bat lived alongside the hoary bat for thousands of years before going extinct shortly after humans arrived on the islands.”
This bat, called Synemporiom keana, was a vesper or evening bat. According to the Bishop Museum’s news release, it “first appeared in the fossil record on the islands around 320,000 years ago and survived until at least 1,100 years ago.” It appears to have coexisted with the hoary bat (Hawaii’s only other endemic land species) for a few thousand years.
But researchers think that ended when humans arrived. “It seems possible that the reduction of native forests and associated insects after human colonization of the islands contributed not just to the extinction of plants, birds, and invertebrates, but also to the extinction of this endemic bat,” said Bishop Museum entomologist Francis Howarth in the news release.
According to the news release, Howarth first discovered the mysterious bat skeleton while exploring a cave on Maui 35 years ago.
He took the fossils to his colleague [Alan] Ziegler, and later they and colleagues found remains on four other islands: Hawaii, Kauai, Molokai, and Oahu. “The initial specimens included skeletons imbedded in crystals on the lava tube wall and thus were likely very old,” Howarth said. “Ziegler eagerly guided me through the bat collection at the Bishop Museum to identify the bat and show me features to look for in order to find additional material for study.” Ziegler immediately recognized that the small bat was very different from anything else he had seen and started the long process of investigating where it sits in the tree of life. He died in 2003 and the project was put on hold until [American Museum of Natural History’s Department of Mammalogy curator-in-charge Nancy] Simmons was brought in to continue the work.
Photo of the skeleton of Synemporion keana embedded in secondary mineral crust on the wall near the downslope end of Mahiehie Cave on Maui: American Museum Novitates