Oesia
disjuncta
Walcott
(1911), who originally described
it from the Burgess Shale as an Annelid worm
Kingdom
Animalia, Phylum Hemichordata (?) recently supported by newer data,
otherwise, incertae sedis
There are
a number of enigmatic metazoans from the great cambrian radiation -
this is one of the more mysterious; Walcott (1911) wrote first description
Geological
Time: Upper Early Cambrian, (~525 million years ago)
Size (25.4
mm = 1 inch): Fossil is 32 mm (curve measure) on a 70 mm by 60 mm and
80 mm by 60 mm matrix pair
Fossil Site:
Marjum Formation, Millard County, Utah
Fossil Code:
STF15
Price: $995.00
|  Description:
The time popularly known as the “Cambrian Explosion” was
one in which many body plans were explored, subsequently being
winnowed down to the phyla we know at present Sometimes enigmatic
animals were shoehorned by early researchers into known phyla
while others were placed in new ones. Work continues even now,
and all researchers are not in universal agreement. This unusual
specimen was named Oesia disjuncta by C. D Walcott when he found
it in the famous Burgess Shale deposits of Canada, and was thought
by him to be a polychaete worm (he had many, many “worms”).
Later, it was thought to be a tunicate, then a chaetognath, and
most recently a hemichordate. Whatever its affinities, it is
most unusual. To my knowledge this is the first example found
outside the Burgess, and displays all the features of the taxon.
The downward-pointing feature in the main photograph is interpreted
as the anterior; the structure at the end may be jawlike in nature.
I have included one photo taken with high-angle polarized light
to help with the interpretation. For a collector of early life
this would be a centerpiece specimen.
Reference:
Acta Palaeontologica Polonica, 54 (1), 2009, pp 175=179.
|
|
