Abstract

A new arthropod Jugatacaris agilis n. gen. n. sp. with excellent soft anatomy is reported from the Early Cambrian Chengjiang biota. Its “bivalved” carapace with a dorsal fin-like fusion is distinct from those of other Cambrian arthropods. A pair of stalked eyes and a prominent median eye protrudes the carapace anteriorly. The cephalon, attaching to the carapace through the lateral adductor muscles at maxillary segment, bears an antennule, antenna and mandible. The trunk is comprised of a large number of segments (varying from 55 to 65), two-thirds of which is covered by the carapace. Each segment, except for the posterior three to five, carries a pair of uniform biramous appendages. The endopodite is composed of 30 podomeres and a terminal claw. The oar-shaped exopododite is fringed with filaments and distally bears a broad setiferous lobe. Trunk terminates with a conical telson and a pair of broad furcal rami serving as steering devices. Internal features like gonad and gut have also been found. The presence of the food groove combined with other morphological features indicates that Jugatacaris was a filter feeder. The appendages design associated with the overall body-plan supports the view that Jugatacaris is a crustaceanomorph. The accurate phylogenic assessment will remain the subject of debate until more information becomes available.

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