Chengjiang Biota “Soft- Bodied Trilobite” DEATH ASSEMBLAGE

Description: The exact taxonomic status of this arthropod is in dispute. It has been termed a “trilobitomorph” by some researchers, showing their beliefs in its close affinity with the trilobites. While the Trilobitomorpha was listed in the Treatise, most now consider that this subphylum is invalid, a catchall much like some of the dustbin terms used by Walcott for a number of the Burgess Shale fauna. Whittington termed it a “soft-bodied trilobite”’ but that belief is not supported at present.

Their similarity in appearance to the Agnoistida is purely a result of convergence. Two large groupings of the Paleozoic arthropods are currently in favor: the Crustaceomorpha (which includes Waptia) and the Arachnomorpha, dominated by the trilobites. The Naraoiidae are arachnomorphs and include Misszhouia and Naraoia. Misszhouia longicaudata was initially placed within Naraoia, but was given its own genus based upon differences between it and Naraoia compacta of the Burgess Shale. The species is one found in several locations within Yunnan Province.

This one is a most unusual specimen as it preserves the remains of at least FOUR examples, the first such death assemblage I have been able to secure. Note that not only is the cuticle outline preserved, but the central gut and some diverticulae in the head region of some examples can be seen.

Also see: Chengjiang Biota