The fossilised remains of a giant burrowing bat that lived in our fine land of New Zealand millions of years ago have been found by a UNSW Sydney-led international team of scientists. Near the town of St Bathans in Central Otago on the South Island was found teeth and bones of the extinct bat. The remains were recovered from 9 to 16-million-year-old sediments and reveal that the bat was about three times the size of the average bat today.
Burrowing bats are notable for foraging more on the forest floor than any other bat species. They are found only in New Zealand now, but they once lived in Australia too. Burrowing bats forage for animals and plants, and scurry about on all fours. This new find represents the first new bat genus to be added to New Zealand’s fauna in more than 150 years.
At an estimated weight of about 40 grams, the bat was the biggest burrowing bat yet known. It has been named Vulcanops jennyworthyae, after team member Jenny Worthy who found the bat fossils, and after Vulcan, the mythological Roman god of fire and volcanoes. The name is a sly reference to New Zealand’s furiously tectonic nature, as well as the historic Vulcan Hotel in the mining town St Bathans.
According to the first author and UNSW Professor Sue Hand:
“Burrowing bats are more closely related to bats living in South America than to others in the southwest Pacific. They are related to vampire bats, ghost-faced bats, fishing and frog-eating bats, and nectar-feeding bats, and belong to a bat superfamily that once spanned the southern landmasses of Australia, New Zealand, South America and possibly Antarctica.”
Around 50 million years ago, these landmasses were connected as the last vestiges of the southern supercontinent Gondwana, the largest continental landmass on Earth, covering an area of 100,000,000 km2(39,000,000 sq mi) or 64% of today’s continents. Antarctica was forested and free of frost, while global temperatures were up to 12 degrees Celsius higher than today. With subsequent fragmentation of Gondwana, cooling climates and the growth of ice-sheets in Antarctica, Australasia’s burrowing bats became isolated from their South American relatives.
“New Zealand’s burrowing bats are also renowned for their extremely broad diet. They eat insects and other invertebrates such as weta and spiders, which they catch on the wing or chase by foot. And they also regularly consume fruit, flowers and nectar,” says Professor Hand, who is Director of the PANGEA Research Centre at UNSW.
“However, Vulcanops’s specialized teeth and large size suggest it had a different diet, capable of eating even more plant food as well as small vertebrates – a diet more like some of its South American cousins. We don’t see this in Australasian bats today,” she says.
Study co-author, Associate Professor Trevor Worthy of Flinders University says: “The fossils of this spectacular bat and several others in the St Bathans Fauna show that the prehistoric aviary that was New Zealand also included a surprising diversity of furry critters alongside the birds.”
Study co-author Professor Paul Scofield of Canterbury Museum says: “These bats, along with land turtles and crocodiles, show that major groups of animals have been lost from New Zealand. They show that the iconic survivors of this lost fauna – the tuataras, moas, kiwi, acanthisittid wrens, and leiopelmatid frogs – evolved in a far more complex community that hitherto thought.”
This diverse fauna lived in or around a 5600-square-km prehistoric Lake Manuherikia that once covered much of the Maniototo region of the South Island. When they lived, in the early Miocene, temperatures in New Zealand were warmer than today and semitropical to warm temperate forests and ferns edged the vast palaeolake.
Vulcanops enables a greater understanding of Australasia’s original bat diversity. As was the case with many lineages present in the St Bathans assemblage, such as crocodiles, terrestrial turtles, flamingo-like palaelodids, swiftlets, several pigeon, and parrots, Vulcanops’ lineage became extinct after the early Miocene. After the middle Miocene, global climate change brought colder and drier conditions to New Zealand, with significant changes to vegetation and environments.
It is thought that this general cooling and drying trend contributed significantly to a loss in bat diversity across New Zealand. Only two bat species comprise the entire native land mammal fauna; all other modern land mammals (such as cats, dogs and possums) have been introduced by people over the last 800 years.
The study, published yesterday in the journal Scientific Reports, was conducted by researchers from Australia, New Zealand, the UK and USA. Research team members include scientists from UNSW Sydney, University of Salford, Flinders University, Queensland University, Canterbury Museum, Museum of New Zealand Te Papa Tongarewa, the American Museum of Natural History, and Duke University.