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FURCULA WARS



The newest _Nature_ has this in the letters pages...

FEDUCCIA, A. and MARTIN, L.D. 1998. Theropod-bird link reconsidered. 
_Nature_ 391: 754

Feduccia and Martin assert that the furcula recently described by 
Norell et al (_Nature_ 389: 447) is not homologous to bird furculae 
because it is rounded in cross-section (therefore unlike the 
caudodorsally grooved design in birds), articulates along the 
entire margin of the coracoid, and cannot be a furcula because 
_Velociraptor_ and kin did  not fly. They also say that the furculae 
of _Longisquama_ indicate how furculae-like structures have evolved 
several times in archosauromorphs.

They also bring up that old chesnut: 'The earliest-known bird, 
_Archaeopteryx_, occurred 75-80 million years ealier than the 
_Velociraptor_ and other Cretaceous theropods that had 'wishbones''. 
They go on to say how all supposed Jurassic furculae are from 
carnosaurs.. 'a group generally thought to be distant from birds - 
although the cladistic analysis of Thulborn (1984) places 
_Tyrannosaurus_ closer to modern birds than to _Archaeopteryx_'.

Oooh, a controversial phylogenetic statement: _Tyrannosaurus_ is back 
in the Carnosauria! Theropod cladists: your hard work has been 
unambiguously overturned!

Of course, Feduccia and Martin cannot get away with all of this, and 
the letter is followed by...

NORRELL, M.A., MAKOVIKCKY, P. and CLARK, J.A.
1998. Theropod-bird link reconsidered: Norell et al reply. _Nature_ 
391: 754.

All of the weak arguments put up by Feduccia and Martin are refuted. 
Exact similarity is not a requirement for homology, the 
_Velociraptor_ furcula does not articulate along its entire length 
with the coracoid, and _Longisquama_ is too controversial to overturn 
the maniraptoran evidence.

And, of course, 'We did not say.. that _Velociraptor_ was a direct 
ancestor, only that dromaeosaurs are related to birds. How do 
Feduccia and Martin explain the presence of primitive living mammals 
such as monotremes and marsupials 100 million years after they split 
from the line leading to ourselves?'.

"Off the record? We were abducted by aliens"

DARREN NAISH
darren.naish@port.ac.uk