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North Island Giant Moa - Dinornis novaezealandiae
Topic Started: Jan 12 2012, 09:23 PM (6,654 Views)
Taipan
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North Island Giant Moa - Dinornis novaezealandiae

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Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Superorder: Paleognathae
Order: Struthioniformes
Family: Dinornithidae
Genus: Dinornis
Species: Dinornis novaezealandiae:

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The North Island Giant Moa (Dinornis novaezelandiae) is one of three extinct moa in the genus Dinornis.

Taxonomy
It is a ratite and a member of the Struthioniformes Order. The Struthioniformes are flightless birds with a sternum without a keel. They also have a distinctive palate. The origin of these birds is becoming clearer as it is now believed that early ancestors of these birds were able to fly and flew to the southern areas where they have been found.

Habitat
This particular moa lived on both the North Island and the South Island of New Zealand, and lived in the lowlands (shrublands, grasslands, dunelands, and forests).

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Extinction
The giant moa, along with other moa genera, were wiped out by human colonists who hunted it for food. All taxa in this genus were extinct by 1500 in New Zealand. It is reliably known that the Māori still hunted them at the beginning of the fifteenth century, driving them into pits and robbing their nests. The most important factor was farming, however, for which the forests were cut and burned down and the ground was turned into arable land.

The moa seems to have died out at the end of the fifteenth century.

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Edited by Taipan, Mar 25 2014, 05:08 PM.
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Giant Moa Had Climate Change Figured out

ScienceDaily (Aug. 3, 2012) — An international team of scientists involving researchers from the University of Adelaide has used ancient DNA from bones of giant extinct New Zealand birds to show that significant climate and environmental changes did not have a large impact on their populations.

The population size of the giant moa remained stable over the past 40,000 years until the arrival of humans in New Zealand around 1280 AD.

The study was undertaken by researchers from the University of Adelaide's Australian Centre for Ancient DNA, the University of Colorado, and the University of Waikato and Landcare Research in New Zealand. The results are published online in the journal Quaternary Science Reviews.

The giant birds -- measuring up to 2.5 metres high and weighing 250 kilograms -- were the largest herbivores in New Zealand's pre-human environment but were quickly exterminated after the arrival of Polynesian settlers.

"Until now it has been difficult to determine how megafauna responded to environmental change over the past 50,000 years, because human arrival and climate change occurred simultaneously in many parts of the world," says Dr Nic Rawlence, lead author of the study and a postdoctoral research fellow from the Australian Centre for Ancient DNA and the University of Waikato.

"Using ancient DNA, radiocarbon dating and stable dietary isotope analysis, we have been able to show that before humans arrived, moa mitigated the effects of climate change by tracking their preferred habitat as it expanded, contracted and shifted during warming and cooling events," Dr Rawlence says.

"Moa were not in serious decline before humans arrived, as has been previously suggested, but had relatively stable population sizes. The overwhelming evidence suggests that the extinction of moa occurred due to overhunting and habitat destruction, at a time of relative climatic stability."

Co-author of the study, Dr Jamie Wood from Landcare Research, says the results "show that range shifts and minor population fluctuations observable in the fossil and genetic record are a natural response to environmental change and do not necessarily lead to extinction."

"Climate change has been blamed for megafaunal extinctions in other parts of the world, but this is not the case for moa," says co-author Dr Jessica Metcalf from the University of Colorado.

ACAD Director and project leader Professor Alan Cooper says: "The very recent extinctions in New Zealand provide a unique opportunity to examine the extinction of Ice Age megafauna and the relative roles of human hunting and climate change."

The study was funded by an Australian Research Council (ARC) Discovery Grant.

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Journal Reference:

Nicolas J. Rawlence, Jessica L. Metcalf, Jamie R. Wood, Trevor H. Worthy, Jeremy J. Austin, Alan Cooper. The effect of climate and environmental change on the megafaunal moa of New Zealand in the absence of humans. Quaternary Science Reviews, 2012; DOI: 10.1016/j.quascirev.2012.07.004

http://www.sciencedaily.com/releases/2012/08/120803114412.htm
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Why the Female Giant Moa Was About Twice the Size of the Male

Apr. 9, 2013 — Some of the largest female birds in the world were almost twice as big as their male mates. Research carried out by the Zoological Society of London (ZSL) shows that this amazing size difference in giant moa was not due to any specific environmental factors, but evolved simply as a result of scaling-up of smaller differences in male and female body size shown by their smaller-bodied ancestors.
In an environment lacking large mammals, New Zealand's giant moa (Dinornis) evolved to be one of the biggest species of bird ever, with females weighing more than two hundred kilograms -- the same as about 3 average sized men.
Male and female birds often show differences in body size, with males typically being larger. However some birds, like many ratites -- large, flightless species such as emus and cassowaries -- are the opposite, with the females towering over the males.
Moa were huge flightless ratites. Several different species inhabited New Zealand's forests, grasslands and mountains until about 700 years ago. However, the first Polynesian settlers became a moa-hunting culture, and rapidly drove all of these species to extinction.
Dr Samuel Turvey, ZSL Senior Research Fellow and lead author on the paper, says: "We compared patterns of body mass within an evolutionary framework for both extinct and living ratites. Females becoming much larger was an odd side-effect of the scaling up of overall body size in moa.
"A lack of large land mammals -- such as elephants, bison and antelope -- allowed New Zealand's birds to grow in size and fill these empty large herbivore niches. Moa evolved to become truly huge, and this accentuated the existing size differences between males and females as the whole animal scaled up in size over time," Dr Turvey added.
Future research should investigate whether similar scaling relationships can also help to explain the evolution of bizarre structures shown by other now-extinct species, such as the elongated canines of sabretoothed cats.

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Sir Richard Owen with skeleton of Dinornis.

http://www.sciencedaily.com/releases/2013/04/130409211939.htm
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Humans to Blame for Giant Bird's Extinction

By Megan Gannon, News Editor | March 24, 2014 09:31am ET

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An artist's rendition of an eagle attacking two extinct New Zealand moa.

Fossils are all that's left of the giant wingless birds called moa that once roamed New Zealand. These big-bodied megaherbivores, some of them weighing up to 550 pounds (250 kilograms), disappeared soon after Polynesians colonized the islands in the late 13th century.

Some researchers had argued the nine species of moa were already in decline by the time humans entered the scene. Others had proposed the birds' population collapsed in the wake of volcanic eruptions or the spread of diseases, before they ever met Homo sapiens. A new study, however, suggests humans are responsible for the birds' demise.

"Elsewhere the situation may be more complex, but in the case of New Zealand the evidence provided by ancient DNA is now clear: The megafaunal extinctions were the result of human factors," Mike Bunce, a professor at Curtin University in Australia, said in a statement.

By looking at the genetic profiles of 281 individual fossil specimens, Bunce and colleagues pieced together the demographic trends across four different species of moa during the 5,000 years leading up to their extinction. They say they found no genetic signatures of decline.

On the contrary, genetic diversity remained consistent and the moa gene pools were "extremely stable throughout their last 5,000 years," said Morten Allentoft, who was a doctoral student in Bunce's lab.

One species, the South Island giant moa (Dinornis robustus), even seemed to be experiencing a population boom with as many as 9,200 individuals roaming about by the time Polynesians landed on New Zealand's shores.

"If anything it looks like their populations were increasing and viable when humans arrived," Allentoft said in a statement. "Then they just disappeared."

Archaeological evidence shows that moa were hunted voraciously and vanished just one or two centuries after humans showed up in New Zealand. In addition to overhunting, other indirect human impacts could have contributed to the moa's quick decline, including fires and the introduction of invasive species.

Bunce believes there are lessons to be learned from the moa's extinction.

"As a community we need to be more aware of the impacts we are having on the environment today and what we, as a species, are responsible for in the past," Bunce said.

The research was detailed this month in the Proceedings of the National Academy of Sciences.

http://www.livescience.com/44291-humans-to-blame-for-giant-birds-extinction.html




Extinct New Zealand megafauna were not in decline before human colonization
Morten Erik Allentofta, Rasmus Hellerd, Charlotte L. Oskamb, Eline D. Lorenzena, Marie L. Halec, M. Thomas P. Gilberta, Christopher Jacombg, Richard N. Holdawayc, and Michael Bunceb,

10.1073/pnas.1314972111
PNAS March 17, 2014

Abstract
The extinction of New Zealand's moa (Aves: Dinornithiformes) followed the arrival of humans in the late 13th century and was the final event of the prehistoric Late Quaternary megafauna extinctions. Determining the state of the moa populations in the pre-extinction period is fundamental to understanding the causes of the event. We sampled 281 moa individuals and combined radiocarbon dating with ancient DNA analyses to help resolve the extinction debate and gain insights into moa biology. The samples, which were predominantly from the last 4,000 years preceding the extinction, represent four sympatric moa species excavated from five adjacent fossil deposits. We characterized the moa assemblage using mitochondrial DNA and nuclear microsatellite markers developed specifically for moa. Although genetic diversity differed significantly among the four species, we found that the millennia preceding the extinction were characterized by a remarkable degree of genetic stability in all species, with no loss of heterozygosity and no shifts in allele frequencies over time. The extinction event itself was too rapid to be manifested in the moa gene pools. Contradicting previous claims of a decline in moa before Polynesian settlement in New Zealand, our findings indicate that the populations were large and stable before suddenly disappearing. This interpretation is supported by approximate Bayesian computation analyses. Our analyses consolidate the disappearance of moa as the most rapid, human-facilitated megafauna extinction documented to date.

http://www.pnas.org/content/early/2014/03/14/1314972111.abstract?sid=254b1b61-3836-4822-a2c5-2e211ec614b2
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