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Dromaeosaurid tails like rhamphorhynchid tails from flight use



From: Ben Creisler
bcreisler@gmail.com

This paper applies to both pterosaurs and theropods so I'm posting it
separately:

W. Scott Persons IV & Philip J. Currie (2012)
Dragon Tails: Convergent Caudal Morphology in Winged Archosaurs
Acta Geologica Sinica - English Edition 86 (6): 1402–1412
DOI: 10.1111/1755-6724.12009
http://onlinelibrary.wiley.com/doi/10.1111/1755-6724.12009/abstract



In the tails of dromaeosaurid dinosaurs and rhamphorhynchid
pterosaurs, elongate osteological rods extend anteriorly from the
chevrons and the prezygapophyses. These caudal rods are positioned in
parallel and are stacked dorsoventrally. The fully articulated and
three-dimensionally preserved caudal series of some dromaeosaurid
specimens show that individually these caudal rods were flexible, not
rigid as previously thought. However, examination of the arrangement
of the caudal rods in cross-section indicates that the combined effect
of multiple caudal rods did provide substantial rigidity in the
dorsoventral, but not in the lateral, plane. The results of digital
muscle reconstructions confirm that dromaeosaurids and
rhamphorhynchids also shared greatly reduced caudofemoral muscles in
the anterior tail region. The striking similarities between the tails
of dromaeosaurids and rhamphorhynchids suggest that both evolved under
similar behavioral and biomechanical pressures. Combined with recent
discoveries of primitive deinonychosaurs that phylogenetically bracket
the evolution of dromaeosaurid caudal rods between two arboreal
gliding/flying forms, these results are evidence that the unique
caudal morphologies of dromaeosaurids and rhamphorhynchids were both
adaptations for an aerial lifestyle.