Grasping Appendage of Anomalocaris, Largest Member Chengjiang Biota
"Terror Of The Cambrian"

Anomalocaris saron

Phylum Uncertain, Anomalocarididae

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

Size (25.4mm=1 inch): 24 mm long on a 25 mm by 23 mm matrix

Fossil Site: Chengjiang Maotianshan Shales, Quiongzhusi Section, Yu’anshan Member, Heilinpu Formation, Ercaicun, Haikou County, Kunming, Yunnan Province, China

Anomalocaris saronDescription: The discovery of the Chengjiang Biota by Hou Xian-guang in 1984 opened a window onto a remarkable array of lifeforms from what is termed the Cambrian Explosion. 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. This is thetip of the grasping arm of the “Terror Of The Cambrian”, AnomalocarisAnomalocaris saron, seen here as a part/counterpart pair. The members of this group of enigmatic creatures are known from Asia, Australia, Europe, and North America, and are thought by many to be closely allied with the Arthropda, as position not held by all researchers. As of the publication of Hou’s book in 2004, some 20 examples were known, most being grasping arms like this one. The spiniferous grasping appendages are strongly suggestive of its carnivorous habits; some trilobites from Utah bear evidence of bite marks that have been attributed to Anaomalocaris. Known only from the Chengjiang biota, this species is closely related to A. canadensis, the type species, from the younger Burgess Shale. The genus derives its name from “anomalous shrimp” which was what the describer thought the appendage was.

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