TURTLE GEESE

[darren.naish@port.ac.uk]

We are, by now, used to hearing how volant/semi-volant dinosaurs may 
have evolved into large-bodied grounded descendants. Reversals and 
adaptations for large size may have made some groups, such as certain 
theropods, exhibit features more 'primitive' than those seen in their 
ancestors. The hands of phorusrhacoids are a superb example. 

Other possible instances of reversal are seen in large flightless 
geese which, in ways, resemble supposedly primitive palaeognathous 
birds like ratites. Regardless, the birds are interesting anyway. 
This recently came out..

JAMES, H.F. and BURNEY, D.A. 1997. The diet and ecology of Hawaii's 
extinct flightless waterfowl: evidence from coprolites. _Biological 
Journal of the Linnean Society_ 62: 279-297.

Coprolites preserved with unfortunate Moa-nalo (aka Turtle-jawed 
geese) of taxon _Thambetochen chauliodous_ (unfortunate because the 
birds that produced the coprolites fell into, and became trapped in, 
Puu Naio Caves) show that they were eating ferns before their death. 
I was thinking that this fact may show that the birds were eating 
what was available, i.e. they could not select plants they really 
wanted to eat, but 'If birds that took their last meal outside the 
cave had eaten something different from birds that fed within the 
cave, we might expect the microfossil spectra to be more 
heterogeneous' (p. 290). So - - fern eating geese! Wow. 

Some moa-nalo (genera _Thambetochen_ and _Ptaiochen_) have 
pseudoteeth, and _Chelychelynechen_ had broad, flat occlusal surfaces 
forming crushing platforms. 

It's funny that the James and Burney paper should appear now, as at 
about the same time, this one came out..

WORTHY, T.H., HOLDAWAY, R.N., SORENSON, M.D.
 and COOPER, A.C. 1997. Description of the first complete skeleton of 
the extinct New Zealand goose _Cnemiornis calcitrans_ (Aves: 
Anatidae), and a reassessment of the relationships of _Cnemiornis_.

_Cnemiornis_ was also a flightless big herbivore, and its robust 
square-tipped bill indicates that it was a grazer. The specimen 
described in this paper is the first pretty much complete skeleton 
found. 

The cladistic analysis of Worthy et al. shows that _Cnemiornis_ is 
most closely related to _Cereopsis_: the Cape Barren goose, something 
long suspected and reasonably logical if you compare the two with 
each other and other anatids. A proverbial spanner in the works is 
Livezey's 1989 study: he even doubted that _Cnemiornis_ was an anatid 
and gave its own family, deemed more basal in Anseriformes than 
Anatidae. However, both _Cereopsis_ and _Cnemiornis_ share unique 
derived characters, and DNA analysis supports a relationship between 
them, exclusive of other birds.

"I was very sceptical.. I thought, Hong Kong !NA!.. having lived out 
there..."

DARREN NAISH
darren.naish@part.ac.uk