The above picture shows a Rachitomous vetebrae and its three elements
in lateral and longitudinal views. It also shows a modern amniotic
vertebra (stereospondylous) for comparison.
- Hatched area - Hypocentrum
- Red area - Pleurocentrum
- White area - Neural Arch
Rachitomi ar no longer regarded as a sub group of the temnospondyls.
Some individual temnospondyls have rachitomous, semi-rachitomous and
stereospondylous vertebrae at different point of their spine. Some also
have intermediate vetebrae that dont appear to fit in anywhere. As such
the Rachitomi are no longer classed as a true sub-order of
stereospondylous vetebrae are classic vertebrae found in the later more
aquatic forms of the temnospondyls. These vetebrae are not equipped for
load bearing means of transport. These vertebrae are completely fused.
There is only one piece of bone as the neural arch has fused with the
pleuro centrum without leaving a suture or any evidence of being two
different elements. This is the condition seen in all modern
amniotes (see picture above). Some experts believe that the
Stereospondyli can still be considered a sub order of the Temnspondyli
though not only because of this shared character.
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