A New View of the Cambrian Arthropod Fuxianhuia

Abstract

Fuxianhuia from the Chengjiang fauna is one of the least derived Cambrian arthropods. A supposed pair of hook-shaped post-antennal appendages (Chen et al. 1995) was later reinterpreted as a pair of gut diverticula situated in a carapace fold (Waloszek et al. 2005). The latter interpretation of the diverticular nature of this structure is verified, but we show that the diverticula are situated inside a head capsule. This capsule carries a pair of antennae. It is shown that the head has also a pair of ordinary locomotory limbs. It is also demonstrated that a number of body segments have more than one pair of legs. There is indication of a possible pair of small eyes in addition to the large pair. The gut may include sediment from the substrate, which indicates that sediment was ingested. Fuxianhuiids share with many lobopodians characters such as a lack of specialisation between and within the ventral appendages. The exopod rises as a lateral fold on a straight limb axis, indicating an origin as a secondary addition to a uniramous limb. The terms Arthropoda s.l. (or pan-Arthropoda) and Arthropoda s.s. are replaced by Aiolopoda Hou & Bergström, 2006, and Arthropoda (in the original sense). The origination of the arthropods is discussed.

Key Words:

• Aiolopoda
• Arthropoda
• biramous limb
• Cambrian arthropods
• Chengjiang fauna
• exopod origination
• great appendage
• gut diverticula
• head capsule
• eye doubling
• Fuxianhuia