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Australia: The Land Where Time Began |
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Cambrian Explosion - Palaeoscolecidae The Palaeoscolecidae is a group extinct forms of
uncertain affinity that had thick bodies that were worm-like and were
covered with calcium phosphate cuticular sclerites. The group has been
interpreted as being peseudocoelomic and it is believed they likely had
ecdysozoan affinities: they have been considered to be likely stem
priapulids (T.H.P. Harvey, Dong & Donoghue, 2010), whereas it has also
been proposed that they are stem Cycloneuralia (Conway Morris & Peel,
2010). In the Cambrian Stage 3 there is a diversity of mineralised
sclerites of palaeoscolecids, and in the Sirius Passet and
Chengjiang
biotas body fossils have been recovered. Among extant pseudocoelomates
most of the worm-like forms are about the correct size to be responsible
for the small burrows and trails that have been recorded from the
Neoproterozoic. The authors1 suggest a better idea of which,
if any, of the ecdysozoans crown groups were likely to have been present
in the fauna of the Neoproterozoic when the phylogenies of these groups
have been sorted out definitively.
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Author: M.H.Monroe Email: admin@austhrutime.com Sources & Further reading |