March 5, 2014

Researchers Work To Clarify Number Of Extinct New Zealand Moa Species

Brett Smith for - Your Universe Online

A report published in the journal PLOS ONE from a pair of researchers at Griffith University in Australia has refined the species status for the New Zealand moa – a large, extinct flightless bird.

"Despite more than 100 years of research being devoted to the issue, determining species status is challenging, especially where there is an absence of substantial morphological, physiological, and behavioral data," explained study author Leon Huynen, a molecular biologist at Griffith.

“Moa were comprised of a relatively large number of species that can be grouped into six genera,” Huynen said. “One of these genera, Euryapteryx, has been difficult to characterize into its constituent species, so this is the genus we have focused upon.”

"Using a DNA barcoding technique we were able to show that two species were likely to have existed in the genus Euryapteryx, with the possibility of some subspecies," Huynen added.

However, study co-author David Lambert said the DNA barcoding technique did not yield evidence that could be used to discriminate between these species.

“Using this DNA barcoding technique we have been able to show that species status in Euryapteryx is very complex with there is no clear separation between various individuals and that this is possibly the result of repeated hybridization events within the genus,” Lambert said.

“Our results do provide a clearer picture of the species status of Euryapteryx, however, and support the suggestion that two species of Euryapteryx may have existed during the Holocene as well as a subspecies (possibly attributable to E. curtus curtus) that is found solely on New Zealand’s North Island,” he added.

A study published in December, which was based on computer tomography (CT) scans of full giant moa skeletons, had found that the giant moas living on New Zealand weren’t as large as originally thought.

Previous similar efforts to gauge the size of an extinct animal have involved basing estimates on leg bones and scaling up according to the size of similar living organisms. However, problems can arise when the bones have abnormal dimensions – as they do in the case of the giant moa.

“If we’d wanted to estimate the weight of a saber-toothed cat, no-one would have suggested measuring canine tooth length and then scaling up the tooth size of your standard tabby,” said study author Charlotte Brassey, a biomechanics researcher at the University of Canterbury in New Zealand. “That’s because we know that the saber-toothed cat had unusually oversized canines compared to house cats. It wouldn’t be a fair comparison, and you’d end up with a ludicrously high estimate of the body weight of the saber-toothed cat.”

“The same was true for moa,” she added. “We already knew that moa had disproportionately wide leg bones, yet previous estimates of their body mass had been based on those same bones which probably resulted in overestimates.”

Using a technique employed by civil engineers, the researchers analyzed the full-skeleton scans to determine that different groups of moa supported their body weight in different ways and each species had a long history of independent evolution.