Grasping Appendage of Anomalocaris from Nevada

Anomalocaris sp

Phylum Uncertain, Anomalocarididae

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

Size: Fossil is 70 mm long

Fossil Site: Comet Shale Member, Pioche Formation, Lincoln County, Nevada

Anomalocaris Grasping Appendage FossilDescription: This is the grasping arm of the “Terror Of The Cambrian”, Anomalocaris, and it comes from the Comet Shale Member of the Pioche Formation of Nevada. This deposit spans the transition of Early to Middle Cambrian which saw the extinction of the Olenellid trilobites. It is just younger than the comparable material from the Chengjiana Biota of Yunnan Province, China and just older than the Burgess Shale Fauna of Brithish Columbia, Canada. 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, a position not held by all researchers. The spiniferous grasping appendages are strongly suggestive of its carnivorous habits; some trilobites from Utah have evidence of bite marks that have been attributed to Anaomalocaris. The genus derives its name from “anomalous shrimp” which was what the describer thought the appendage was. The specimens from the Pioche Formation are often somewhat faint. The specimen has been water wet to heighten contrast, and I include a negative image of the main slab to make it easier to see. Regardless, this is a rare specimen, little seen outside of an academic collection.

click to enlarge

Fossil Museum Navigation:
Fossils Home
Geological Time Paleobiology Geological History Tree of Life
Fossil Sites Fossils Evolution Fossil Record Museum Fossils