Dinornis
Including D. novaezealandiae, a.k.a. the North Island Giant
Moa,
and D. robustus, a.k.a. the South Island Giant Moa.
Name: Dinornis
(Terrible bird).
Phonetic: Die-nor-nis.
Named By: Richard Owen - 1843.
Synonyms: Dinornis struthioides,
Dinoris, Moa, Movia, Owenia, Palapteryx, Tylopteryx.
Classification: Chordata, Aves, Paleognathae,
Dinornithiformes, Dinornithidae.
Species: D. novaezealandiae, D.
robustus.
Diet: Herbivore.
Size: At maximum elevation, 3.6 meters high
(for females, see main text for details).
Known locations: New Zealand.
Time period: Late Pleistocene to Holocene.
Fossil representation: Multiple specimens of males
and females.
When
you are presented with an image of a moa
bird, chances are you are
looking at Dinornis, which internationally is the
most famous of the
moa. This fame is mostly down to the immense size of Dinornis,
individuals of which at full elevation of the neck could reach up to
just over three and a half meters high. Feathers of Dinornis
have
even been recovered, study of which reveals that in life Dinornis
would have been a reddish brown in colour. However, being
secondarily flightless, the feathers had ‘de-evolved’ into more
primitive hair-like structures. These would have provided not only
insulation, but a weatherproof coat that kept the skin dry when it
rained. Only the legs as well as parts of the head and throat were
devoid of feathers. Like its relatives, Dinornis
had small heads
with a beak that curved slightly downwards. This beak allowed
Dinornis to selectively snip off small portions of
the most edible
plants of the forests that once covered all of New Zealand.
In
the past Dinornis has been treated as something
of a wastebasket
taxon with almost any moa remains being attributed to Dinornis
upon
their discovery. This has led to the Dinornis
genus previously
attaining one of the longest species name lists of any moa, but
fortunately, later palaeontologists that inherited moa study from
their forebears realised for themselves that something was up. Later
study of Dinornis remains has now seen most of the
fossils of former
species re-assigned to different moa genera, while a few species such
as D. struthioides were found to be synonyms to
existing Dinornis
species. At the time of writing there is now just two universally
recognised species of Dinornis. These are D.
novaezealandiae from
the North Island, and D. robustus of South
Island.
The
Dinornis genus of moa is perhaps the best example of
the extreme sexual
dimorphism that can be seen in these birds. The females of Dinornis
can be as much as one and a half times taller than the males, and at
the same time be almost three times as heavy. So extreme were these
size differences that males and females were once thought to be
separate species, with males being classed under D.
struthioides,
and females under D. robustus. It was not
until the advent of DNA
analysis that the truth was discovered and that D.
struthioides
became a synonym to D. robustus.
DNA
analysis of Dinornis specimens has also revealed
the presence of two
previously unknown lineages within known Dinornis
fossils. This means
that in the near future two new species of Dinornis
may become listed,
but at the time of writing further details on these are unavailable.
The use of DNA analysis in Dinornis however also
illustrates how
palaeontologists are continually trying out and using techniques
originally designed for other scientific areas to help them to
understand and reveal more of the truth about long extinct animals.
Unfortunately however, the vast majority of fossils of extinct
animals in general do not contain any testable DNA, they have just
been fossilised for too long.
Care
should be taken not to confuse Dinornis with the
similarly named
Dromornis
from Australia.
Further reading
- On the remains of Dinornis, an extinct
gigantic struthious bird
- Richard Owen - 1843.
- Extreme reversed sexual size dimorphism in the extinct New Zealand
moa Dinornis - Michael Bruce, Trevor H.
Worthy, Tom Ford,
Will Hoppitt, Eske Willerslev, Alexei Drummond & Alan
Cooper - 2003.
- Nuclear DNA sequences detect species limits in ancient moa -
L. Huynen, C. D. Millar, R. P. Scofield & D.
M. Lambert - 2003.
- Reconstructing the tempo and mode of evolution in an extinct clade
of birds with ancient DNA: The giant moas of New Zealand - Allan
J. Baker, Leon J. Huynen, Oliver Haddrath, Craig D. Millar
& David M. Lambert - 2005.
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