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Flexibility of Ostrich Necks: Implications for Sauropod Neck Posture



J Morphol. 2007 May 18; [Epub ahead of print]  

Flexibility along the neck of the ostrich (Struthio
camelus) and consequences for the reconstruction of
dinosaurs with extreme neck length.Dzemski G,
Christian A. 
Institut fur Biologie, Department IV, Universitat
Flensburg, 24943 Flensburg, Germany.

The gross morphology and the flexibility along the
neck of the ostrich (Struthio camelus) were examined
using fresh tissue as well as neck skeletons. The
results of the morphologic studies were compared with
results from observations of living ostriches. The
investigation was focused on differences in the
morphology and the function between different sections
of the neck. Additionally, the function of major
dorsal neck ligaments was examined, including
measurements of force-strain-relations. Comparative
studies of giraffes (Giraffa camelopardalis) and
camels (Camelus bactrianus) were conducted to find
relations between the flexibility along the neck and
the general feeding strategy. The examinations
revealed that the neck of the ostrich can be divided
into four sections with different functions. The first
is the atlas-axis-complex which is responsible for
torsion. The adjacent cranial section of the neck is
flexible in dorsoventral and lateral directions but
this part of the neck is usually kept straight at rest
and during feeding. Dorsoventral flexibility is
highest in the middle section of the neck, whereas the
base of the neck is primarily used for lateral
excursions of the neck. For giraffes and camels, the
posture and utilization of the neck are also reflected
in the flexibility of the neck. For all three species,
it is possible to reconstruct the pattern of
flexibility of the neck by using the neck skeletons
alone. Therefore, it appears reasonable to reconstruct
the neck utilization and the feeding strategies of
dinosaurs with long necks by deriving the flexibility
of the neck from preserved vertebrae. For Diplodocus
carnegii the neck posture and the feeding strategy
were reconstructed. Two neck regions, one around the
9th neck vertebra and the second at the base of the
neck, indicate that Diplodocus, like the ostrich,
adopted different neck postures. The neck was probably
kept very low during feeding. During interruptions of
the feeding, e.g., in an alert, the head could have
been lifted in an economic way by raising the cranial
section of the neck. During standing and locomotion
the head was probably located well above the
shoulders.