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is about 80% of the external tarsal length of females of Megapodius
laperouse laperouse (50-55 mm), the smallest living
species of megapode. The proximal and distal widths of the tarsometatarsus
of Ngawupodius are proportionally great compared
to its total length: about 21% for both measurements, at
the top of the range among megapodes (15%-21%). Likewise,
Ngawupodius has a proportionally wide middle shaft (10.6% of
total length, range of megapodes 6%-ll%; 45% of distal
width, 38%-45% in other species). In these proportions
Ngawupodius resembles only Leipoa (Figure ID). Comparisons
with Progura are not possible from existing material. The
structure and length of the tarsometatarsus in Leipoa may be
related to its more open habitat, and the resemblances to
Ngawupodius could be coincidental.
Given what is known of living species, a general range of
size can be proposed for Ngawupodius. If it had disproportionally
short legs, as in Leipoa, then it may have been similar in
body length and weight to the smallest species of Megapodius.
If the leg proportions were more typical of the other megapodes,
then estimates of about 225-235 mm overall length and
230-330 g are reasonable. The small, undescribed species of
Megapodius from 'Eua, Tonga, appears to have been of comparable
size to Ngawupodius minya (D. Steadman, pers.
comm., 1996).
On the basis of pollen of grasses and subtropical rainforest
flora from the lower member of the Namba Formation, Tedford
et al. (1977:56) suggested a paleohabitat of "riparian forests
with savannas on better drained fluviatiles." Some related but
specifically distinct mammals in the faunas of the two members
were inferred by Tedford et al. (1977) to indicate that the
division between them recorded both a change in the depositional
environment and a significant time gap. If the general
vegetation in the upper member remained much the same as
that suggested by the pollen from the lower member, then it is
tempting to envisage a situation much like that in northern
Australia today. The Orange-footed Scrubfowl, Megapodius
reinwardt, frequents riparian forests bordered by tropical savanna
woodland. Ngawupodius may have occupied a similar
habitat in the Oligocene environment of Lake Pinpa.
Balouet, Jean Christophe, and Storrs L. Olson
1989. Fossil Birds from Late Quaternary Deposits in New Caledonia.
Smithsonian Contributions to Zoology, 469:38 pages, 16 figures.
Baumel, Julian J., and Lawrence M. Witmer
1993. Osteologia. In J.J. Baumel, A.S. King, J.E. Breazile, H.E. Evans,
and C. Vanden Berge, editors, Handbook of Avian Anatomy: Nomina
Anatomica Avium. Publications of the Nuttall Ornithological
Club, 23:45-132, figures 4.1—4.18.
Boles, Walter E., and Brian Mackness
1994. Birds from the Bluff Downs Local Fauna, Allingham Formation.
Literature Cited
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
The extinction of Ngawupodius was neither through competition
with pheasants nor predation by felids. The only phasianids
known from the Australian fossil record or occurring in a
natural state in Australia today are small quail of the genus
Coturnix (up to 120 g). These are too small to compete actively
with megapodes, even Ngawupodius. Coturnix is known from
other late-Oligocene-aged central Australian sites, although not
Lake Pinpa. Pheasants, partridges, or other galliforms of a size
comparable to any of the megapodes are not known from Australia.
Likewise, the Felidae and Viverridae do not occur in
Australia, and there is no evidence that marsupial carnivores
have a particularly deleterious effect on megapode populations.
Marsupial carnivores were well represented in Australia during
the Oligocene and also have been found in the Ericmas Fauna
(Dasyuridae).
If it left no descendants, the eventual extinction of Ngawupodius
may be related to a changing environment. With the late
Miocene drying of Australia, the wet forest vegetation that apparently
was its habitat was lost from the center of the continent.
Similar habitats are now restricted to parts of eastern and
northern Australia. Other central Australian birds that were lost
after these climatic alterations were aquatic forms (e.g., flamingos,
Phoenicopteridae). It is not yet possible to verify the loss
of other terrestrial birds because these are not well represented,
and existing material has yet to be studied in any depth.
The morphology of Ngawupodius holds no clues to its relationships
within the family; it shares osteological characters
with most genera of megapodes. Until a complete phylogenetic
analysis of the Megapodiidae is performed, the polarities of
these characters will not be known. Likewise, whether
Ngawupodius was ancestral to any of the living forms, and if
so, how directly, cannot be determined. Similarities in proportions
and its occurrence in central Australia raise the possibility
that Ngawupodius may have been a direct ancestor of Leipoa.
Conversely, Ngawupodius may have represented a distinct lineage
within the family. There is general agreement that, regardless
of their center of origin, megapodes were isolated in Australo-Papua
for an extended period, which we know now to
extend at least to the late Oligocene, Ngawupodius being the
oldest known member of the Megapodiidae.
Records of the South Australian Museum, 27(2): 139-149,2 figures.
Brom, T.G., and R.W.R.J. Dekker
1992. Current Studies on Megapode Phylogeny. In R.W.R.J. Dekker and
D.N. Jones, editors, Proceedings of the First International Megapode
Symposium, Christchurch, New Zealand, December 1990. Zoologische
Verhandelingen, 278:7-17, figures 1-5.
Callen, Roger A., and Richard H. Tedford
1976. New Late Cainozoic Rock Units and Depositional Environments,
Lake Frome Area, South Australia. Transactions of the Royal Society
of South Australia, 100(3): 125-168, 24 figures.