EARTH’S NEWEST CONTINENT:
ZEALANDIAFor decades geologists have suspected that a substantial, unified
expanse of continental crust, covered by the Pacific Ocean and
masquerading as a string of rises and islands east of Australia, met
the criteria to be considered a geological continent. Now, Nick
Mortimer and colleagues have used satellite and marine geology
data to advance the case for recognising ‘Zealandia’ – a moniker
first coined by Bruce Luyendyk in 1995 for the area comprising
New Zealand, the Lord Howe Rise, Chatham Rise and Campbell
Plateau. Zealandia’s 4.9 million km^2 area is roughly the same area as
greater India. Although 94% of the new continent is submerged, it
represents the youngest and thinnest continent. Its crust thickness
of 10–40km (the latter beneath New Zealand’s South Island) is
thicker than that of ocean crust, which is typically only 7 km thick.
Today, only New Zealand and New Caledonia rise above sea level,
but Zealandia is believed to have once made up some 5% of the
larger Gondwana supercontinent before breaking away in the Late
Cretaceous, 60–80 million years ago. Coming remarkably close to
the Australian plate in places – separated by just 25 km across the
3600-km-deep Cato Trough off the Queensland coast – Zealandia
exists in a volatile zone between the rigid Pacific and Australian
plates, so has undergone considerable continental rift and
deformation over time.
Mortimer N. et al. 2017. GSA Today. DOI: 10.1130/GSATG321A.1WHAT’S AMISS ABOUT AUSTRALIA’S ABYSS?
In one word – knowledge! The Australian abyss is the largest and deepest habitat on the
planet. It covers half the world’s oceans and one third of Australia’s territory, but it remains
the most unexplored environment on Earth. The recent ‘Sampling the Abyss’ voyage on
the RV Investigator aimed to change that. For 31 days, a group of scientists and specialists
from 14 institutions and 7 countries sampled sites along the eastern Australian abyss, from
off north-eastern Tasmania to the Coral Sea, mapping the seafloor and discovering a deep,
dark underwater world of canyons, mountains and amazing animals, many previously
unknown to science. The team discovered media-sensations the ‘faceless fish’ (a rare species
of cusk eel first recorded over a century ago) and the ‘peanut worm’, as well as a spiny king
crab, monkey brittle-stars (left) and zombie worms, and has only just started the research
that will help us understand and protect this important marine environment. Sampling the
Abyss was led by Museums Victoria under Chief Scientist Dr Tim O’Hara and supported by
CSIRO Marine National Facility and NESP Marine Biodiversity Hub.
Blogging the Abyss (www.nespmarine.edu.au/abyss-landing-page)HALF A CENTURY IN HIDING
First described by Charles Walter De Vis in 1897 and classified
as a distinct wild dog species (Canis hallstromi) in 1958, the
New Guinea highland wild dog seemed to have vanished in the
wild for more than half a century, leading some to believe it
had gone extinct.
However, in late 2016, when James ‘Mac’ McIntyre and the
University of Papua (UNIPA) rapid survey team discovered a
distinct dog spoor following their footprints up a muddy track
in the remote, high-altitude Puncak Jaya region of New Guinea,
this elusive canine species was dramatically ‘rediscovered’. Baits
and trail cameras were immediately set up, within days capturing
more than 140 photographs. Over time, the team was able
to locate and observe living dogs and take biological samples,
using DNA testing to confirm that these were indeed wild
representatives of the species. Controversy continues over
the phylogenetic relationship between C. hallstromi and the
Australian dingo (C. lupus dingo) and whether the highland wild
dog is ancestral. Captive populations of about 200 dogs, bred
from individuals captured in New Guinea from 1956 to 1976,
are usually referred to as New Guinea singing dogs (pictured).
DNA tests will now be undertaken to determine whether they are
the same species. Some believe the discovery could help answer
questions about canid evolution and domesticity, representing
a proto-domestic ‘missing link’ in Asian wild dog species. Initial
DNA analysis carried out at UC Davis has determined that the
highland wild dog possesses the A29 haplotype, as do the dingo
and the New Guinea singing dog. A second expedition to the site
is planned, and further DNA analysis is underway.
Worthington, K. 30 April 2017. ‘Dingo relative rediscovered in remote highlands of
New Guinea’. ABC online
Photo: Rob Zugaro, Museums VictoriaPhoto: Patti McNeal [CC]Photo: Janette AscheWildlife Australia | 49