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Subject: Archaeopteryx article



From: Ben Creisler bh480@scn.org
Subject: Archaeopteryx article

Can't recall if the following paper has been mentioned 
here, so I'll cite it anyway:
Elzanowski, A. & Pasko, L. 1999. A skeletal reconstruction 
of  Archaeopteryx. Acta Ornithologica 34(2):123-129.

Abstract: A novel, skeletal reconstruction of 
Archaeopteryx skeleton follows Heilmann's (1926) tradition 
in being based primarily on osteological and free 
phylogenetic and functional reconceptions. Although the 
connection between the sternum and ribs remains unknown, a 
combination of positional and comparative evidence speaks 
for the presence of cartilaginous sternal ribs. The 
reconstructed rib cage is compatible with some levels of 
the airsac ventilation mechanics. The reconstructed 
segmental position (relative to the vertebral column) of 
the shoulder girdle at the level of the 11th or 12th 
vertebra agrees with evidence from both modern birds and 
theropods. The wing must have been largely folded in the 
resting position, but the geometry and mechanism of wing 
folding remain conjectural. In its gait and stand, 
Archaeopteryx was more similar to the modern birds than to 
the theropods.

The paper argues that recent reconstructions by Ostrom and 
Paul are based on too many assumptions about the dinosaur-
nature of Archaeopteryx, and read features into the 
material that can't be justified. In particular, the idea 
that Archaeopteryx had a hyperextended "slashing" second 
toe a la Deinonychus is rejected.  Martin's "winged 
monkey" approach (with upright posture and raised tail) 
gets even rougher treatment ("Martin's 'model' cannot be 
treated seriously..."). They authors opt for a what they 
hope is a reconstruction "free of phylogenetic and 
functional bias." They also cite a paper scheduled for 
publication in the still forthcoming book Mesozoic Birds: 
Above the Heads of Dinosaurs that argues for a different 
reconstruction of the skull. They also cite unpublished 
data that "the known archaeoptergyid specimens most 
probably represent several different species...and thus 
most of the restorations are composites."
Since the topic came up, does anyone have any word on when 
Mesozoic Birds: Above the Heads of Dinosaurs will appear? 
It's not mentioned on the University of California Press 
website among fall books so I assume it's scheduled for 
the winter (if it's to be a 2000 book as indicated in 
citations). Speaking of new books, what happened to 
Unwin's volume about pterosaurs? The massive volume about 
Mongolian dinosaurs is still scheduled for October 
publication as far as I know.