Remains of giant horned turtles found at an even older human cemetery in Vanuatu have revealed that the first settlers shared a Pacific island with the turtles for at least two centuries.
Researchers have also discovered that subsequent settlers killed, butchered and ate the turtles and dumped their bones on top of their predecessors' graves, according to a new study published in the journal Proceedings of the National Academy of Sciences.
The study by palaeontologists Dr Arthur White and Dr Trevor Worthy, of the UNSW School of Biological, Earth and Environmental Sciences, and a team of archaeologists from the Australian National University has unearthed fascinating details of the unusual turtle graveyard and bone bed.
Fossils of the huge land-dwelling reptiles, known as meiolaniid turtles, are known from Australia and Argentina by rare remains often millions of years old, but are best known from Lord Howe Island where bones are many tens of thousands of years old.
They were land-dwelling turtles with heads that featured multiple horns - and so could not be retracted beneath their massive armoured shells - and large knobby tails. The species found at Vanuatu is new to science. Its bones are also the most recent remains of this enigmatic family known.
The graves are those of the Lapita people, the first colonisers of eastern Melanesia and Polynesia. They are best known for their decorated earthenware pottery.
It is at Teouma, on the south coast of Efate Island, Central Vanuatu. The site was once adjacent to the sea but following subsequent geological events it is now about 800 metres from the coast.
"It is the first time this family of turtles has been shown to have met with humans and there are many turtle bones in the middens," says Dr White. "Initial excavations in 2004 by the ANU team revealed that the first use of the site was as a cemetery and provided the first real opportunity in more than 50 years of research to describe a group of Lapita people and glean insights into their ritual and mortuary practices."
The middens are immediately post-Lapita waste dumps dating to about 2500-2800 years ago and are deposited – perhaps unknowingly - where earlier burials had taken place, about 2900-3000 years ago. Some human bodies in the graves had their heads removed after death and placed in pots.
The turtle bones are mainly of the animals' haunches, with very few shells, and are headless. "This biased skeletal representation suggests butchering at more remote locations, perhaps inland, and transport back to the village," says Dr Worthy. "We are hoping the ongoing excavations will find middens from the first settlers and with them there should be more complete turtle remains."
It has been shown that just before human arrival at Teouma, a thick layer of volcanic debris known as tephra was deposited across the site, creating a level surface across a once-jagged uplifted reef. Excavations have revealed 66 burials of over 85 individuals, who were placed in shallow graves dug into places where tephra had filled gaps in the former reef.
The site apparently later lost its cultural significance and was used as a village waste dump, covering the graves. Increasing problems with access to the sea apparently led to the abandonment of the settlement, with no signs of use or occupation until the development of a coconut plantation about 100 years ago.
UNSW: Dr Trevor Worthy – 02 9385 2125 firstname.lastname@example.org