Chancelloria Fossils Assemblage

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

Chancelloria pentacta FossilsDescription: 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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