Cyclomedusa
davidi & Hiemalora stellaris
Geological
Time: Precambrian, Vendian (600 - 550 Million Years Old)
Size: Cyclomedusa
40 mm X 37 mm; Hiemalora 40 mm X 30 mm
Fossil
Site: White Sea Summer Coast, Archangelsk, Russia
Description:
This spectacular death assemblage predates the Cambrian Explosion
by tens of millions of years. Many early attempts at diversity were
present during this time, both here and in the Ediacara Fauna of
the Flinders Ranges
of Australia. Many strange forms were present, some of which still
do not have any parallels in modern times. These jellyfish-like
examples are one that is relatively easy to attribute to descendants
alive today. The incredible soft-bodied preservation is believed
to be the result of impressions made
in a microbial mat contained within the sand. There is debate about
the true nature of both these examples. Cyclomedusa was initially
thought to be a pelagic jellyfish, but is now more likely a benthic
organism much like a sea anemone.
The
one below it was thought to possibly be a member of the Cnidaria
by virtue of its tentacle-like structures. Given that Cyclomedsa
is not found with preserved tentacles, Hiemalora is now thought
to be the anchor of some larger, as yet unknown creature. |
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