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Way cool kagu



Until it was mentioned recently on the list I did not even know about the 
kagu (so did not discuss in DA). Since it is the only living nearly 
flightless bird with big wings it is very important, and I wanted to see the 
skeleton. Was afraid would have to go all the way down to the Smithsonian and 
arrange to get into birds and so on and so forth. But right there on Google is 
an 
old figure of the skeleton via Parker 1868 bless em, the paper is on the web 
(it starts with rather a bit of a tiff with Professor Huxley over the 
proper identity of the great maxilla before it gets down to describing the kagu 
- 
ah those were the days:-). Also on Google is an excellent photo of a kagu 
with its wings held up in display, showing the entire left ventral surface 
flat on to the camera. So did a skeletal restoration with the wing profile 
(was able to get the correct wing size on the skeleton by using the lengthes of 
the arm, head and metatarsus which all produced similar results). 

The kagu is a set of really long legs anchored on a very big pelvis 
attached to a remarkably short,  deep body, and a very large head with big 
eyes.  

The area of the wing is typical for a flying bird at its mass and similar 
to Archaeopteryx and Microraptor. Yet there are remarkably few primary (they 
are asymmetrical) and inner feathers, just 16 along the whole span of the 
wing. The sternum lacks a keel and is very narrow. Sternal ribs look normal, 
uncinates rather small. Really notable is that the furcula is very thin, and 
the coracoid is quite narrow. Scapula blade rather reduced. The humerus 
shaft is slender, especially at mid shaft, being much weaker than the femur. 
The 
pectoral crest is hardly there. The very thin furcula and teeny pectoral 
crest suggest extreme reduction of flight muscles. The leg muscles onthe 
oversized pelvis and long long limbs must be a far larger percent of total 
mass. 
Toe claws are flat of course, short, tips seem to be worn a bit. Kagus are 
adapted for running and not flying. They show what a full winged but nearly 
flightless ground dwelling theropod looks like. 

Archaeopteryx does not have an ossified sternum. But the furcula is much 
more robust, the pectoral crest is many, many times larger, and the coracoid 
is broader. The humerus is more robust than the femur. The pelvis is dinky 
and the legs are not all that long, toes claws are large, shapr and more 
curved. The arm muscles should have been stronger than those of the legs, 
indicating that the arms were the main locomotary organs via some level of 
powered 
flight (probably better than kagu) and quad climbing. This is what a 
scansorial winged theropod looks like. 

Microraptor also has very large pectoral crest, stout furcula and coracoid, 
plus a sternal plate that is broader than that of a kagu, and a flattened 
central finger to support the outer primaries not present in Archaeopteryx. 
The legs are very long, but that is because they too are supporting big 
wings. Pelvis is rather small. Toe claws big, strongly arced and very sharp. 
Must 
have been a better powered flier and climber than Archaeopteryx. This is 
what a highly arboreal winger theropod looks like.  

What we really need is a lot more data on the kagu. So one of you get a 
grant to go to New Caledonia (very nice place, McCale and his PT 73 crew went 
on leave there, is big tourist beach destination for the French). Find out 
exactly what their flight abilities are and are not. Really badly needed is 
the weight of the combined flight muscles as a percent of body mass (also of 
leg muscles). So kill a kagu or two - never mind that they are endangered and 
it is very illegal - and get that data. How's that for a project? 

Of course we will probably never know the exact size and nature of kagu 
flight muscles. Sigh. 

GSPaul</HTML>