Parapaleomerus, An Extremely Rare Arthropod from Chengjiang

Description: This exceptionally rare arthropod is known as Parapaleomerus sinesis. The species was known from only THREE examples as of the publication of Hou’s book in 2004. The diversity of soft-tissue fossils is astonishing: algae, medusiforms, sponges, priapulids, annelid like worms, echinoderms, arthropods (including trilobites), hemichordates, chordates, and the first agnathan fish make up just a small fraction of the total. Numerous problematic forms are known as well, some of which may have represented failed attempts at diversity that did not persist to the present day.

The taxon is similar to Paleomerus (hence the name), and may indeed be the same genus. Paleomerus is regarded by some researchers as a basal chelicerate. P sinensis bera some likeness to the Burgess Shale arachnomorphs Ermeraldella and Molaria, but does not possess the long telson of those taxa. Since only the shell is known, the appendages in the artist’s rendering are conjecture