Isoxys auritus Chengjiang Arthropod

with Preserved Eyes

Isoxys auritus

Phylum Arthropoda

Geologic Time: Early Cambrian (~525 million years ago)

Size (25.4 mm = 1 inch): 45 mm long by 15 mm tall on a 57 mm by 80 mm matrix

Fossil Site: Chengjiang Maotianshan Shales - Quiongzhusi Section, Yu’anshan Member, Heilinpu Formation, Mafang Village, Yunnan Province, China

Fossil Code: SRC09

Price: Sold


Isoxys auritus Chengjiang FossilDescription: This unusual arthropod is known as Isoxys auritus. The species is known mostly from the distinctively–pointed bivalved carapace, but specimen has both eyes preserved in great detail, the FIRST such example I have been able to obtain where both eyes can be clearly seen. The diversity of soft-tissue fossils is astonishing: algae, medusiforms, sponges, priapulids, annelid-like worms, echinoderms, arthropods (including trilobites), hemichordates, chordates, and the first Isoxysagnathan 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 only rarely preserved with any soft parts evident. Based upon the few known examples, it had a long segmented body, forwardly-projecting stalked eyes, and short antennae. The swimming appendages and most other soft parts only protruded slightly from their protective shell. This taxon is known only from the Chengjiang Biota, but other members of the genus are found in deposits in Europe, Australia, and North America. New specimens of Isoxys from both Chengjiang and the younger Burgess Shale have allowed researchers to ally them with the ‘great appendage arthropods”. Their large eyes would have served them well in tracking down prey.

Reference: Proceedings of the Royal Society B, 29 April 2009 (published online).

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