A new Induan (Early Triassic, Dienerian) cyclidan crustacean from the Guiyang biota

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Abstract The order Cyclida is a distinct group of crustaceans. However, our knowledge of cyclidan crustaceans is very limited due to their rarity in the fossil record. Usually, only the hard carapaces are preserved, while their antennules and appendages are extremely rare. Here, we describe a new cyclidan species, Yunnanocyclus fortis sp. nov., on the basis of three well‐preserved specimens from the Early Triassic Guiyang biota, which is known as the oldest Mesozoic lagerstätte. The new species has an ovoid carapace, narrow and smooth marginal rim, a pair of antennules, antennae and seven pairs of thoracomeres. Using μ‐XRF analysis, we found that the new species has a pair of strongly ovoid mandibles. The discovery of a new species from South China expands the palaeogeographic distribution of Early Triassic cyclidans. Combining the new species and other reported Cyclida morphological data, we constructed the morphospace of Cyclida using NMDS analysis. The morphospace of Cyclida shows no significant morphological innovations from the Carboniferous to the Triassic, and the high degree of morphological divergence in the Carboniferous supports the early burst model.

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