Chancelloria
pentacta
Phylum
incertae sedis, Extinct Class†Coeloscleritophora, Order Chancelloriida,
Family Chancelloriidae
Geological
Time: Middle Cambrian
Size: The
fossils range from 2 3/8 to 2 1/2” in length on a 3 3/8 x 3 1/8” plate
Fossil Site:
Wheeler Shale Formation, House Range, Utah
 Description:
Presented is an association of four Chancelloria pentacta, enigmatic
fossils of the Cambrian Explosion. They are all parallel to one
another. The two center ones appear to be a bit over-lapping.
The Chancelloria
are a
bit ethereal, almost floating on the plate. One of the characteristics
of this most aesthetic fossil is the star-shaped scierites.
Chancelloria is a genus of early animal known from the Middle
Cambrian Burgess Shale and Wheeler Shale and elsewhere. It was
first described in 1920 by Charles Doolittle Walcott, who regarded
them as one of the most primitive groups of sponges. This appears
unlikely, and it is currently placed in the enigmatic group Coeloscleritophora.
Classifying the chancelloriids is difficult. Some paleontologists
classify them as sponges, an idea which chancelloriids' sessile
lifestyle and simple structure make plausible. Other proposals
suggest that they were more advanced, or at least originated from
more advanced ancestors; for example chancelloriids' skins appear
to be much more complex than those of any sponge. It has been suggested
that chancelloriids were related to the "chain mail" armored
slug-like halkieriids, which are important in analyses of the Cambrian
explosion. The chancelloriids had bag-like bodies with an orifice
at the top, and show no evidence of internal organs.
Related: Soft-bodied
Cambrian Explosion Biota from Utah
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