Dated to 16 million years, while the oldest known bat in New Zealand dates back to 17,500 years, this fossil has surprised paleontologists. The discovery increases knowledge about one of the only native mammals land of the archipelago which its semi-terrestrial feeding method and diet close to current bats document the development of the forest ecosystem.
The ancestor of a bat species from New Zealand would be 16 million years back, according to a study published in the journal Plos One. New Zealand’s only native terrestrial mammals are three bat species: the insectivorousChalinolobus tuberculatus (Forster, 1844) and the omnivorous Mystacina tuberculata Gray, 1843 and M. robusta Dwyer, 1962. Chalinolobus tuberculatus belongs to the cosmopolitan bat family Vespertilionidae.
The fossil that enabled this time stamping was discovered in sediments of Lake Manuherikia on the South Island. Paleontologists have also unearthed fossil specimens of frog, lizard, bird, crocodile and turtle and were able to establish that the surrounding forest, at that time was subtropical type and little different of the current ecosystem region.
Named Mystacina miocenalis, based on its geological era, the Miocene, fossil bat provides more information from the structure of its skeleton, the species was crawling on the forest floor using its four limbs, much like current burrowing for meat in the litter.
Mystacina miocenalis also had strikingly similar teeth to its modern relatives, suggesting close diets and compounds of nectar, pollen, fruit, insects and spiders.
The history of bats illuminates the forest
Weighing 40 grams, the ancestor was however three times heavier than the current Mystacina tuberculata. For researchers, this is unusually large for this flying mammal and suggests that he hunted more on ground than in the air and ate prey heavier and larger fruits than his living relative.
While the previous oldest fossil of Mystacina showed furthermore 17,500 years old, “our discovery shows for the first time that bats Mystacina were present in New Zealand for over 16 million years, residing in very similar habitats to current forms of plant life and food sources, “says Suzanne Hand, a paleontologist at the University of New South Wales, Australia, and lead author of the study.
The evolutionary history of bats Mystacina is much longer than assumed and questions the period to which the first individuals migrated from Australia. “Bats are important pollinators and seed dispersers that maintain forest health,” says Suzanne Hand. According to her, understand the connectivity between faunas of bats from different regions is important to assess biosecurity threats and the conservation priorities of the fragile island ecosystems.