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Readers here might enjoy this paper from the new Nature:

Vertebral architecture in the earliest stem tetrapods

Stephanie E. Pierce, et al.
The construction of the vertebral column has been used as a key anatomical
character in defining and diagnosing early tetrapod groups1  . Here we
describe the three-dimensional vertebral architecture of the Late Devonian
stem tetrapod Ichthyostega using propagation phase-contrast X-ray
synchrotron microtomography. Our scans reveal a diverse array of new
morphological, and associated developmental and functional, characteristics,
including a possible posterior-to-anterior vertebral ossification sequence
and the first evolutionary appearance of ossified sternal elements. One of
the most intriguing features relates to the positional relationships between
the vertebral elements, with the pleurocentra being unexpectedly sutured or
fused to the intercentra that directly succeed them, indicating a ?reverse¹
rhachitomous design