Yicaris
Species of microscopic crustaceans
From Wikipedia, the free encyclopedia
Yicaris dianensis is a species of microscopic pancrustacean[1][2] found in the Yu’anshan Formation, Yunnan Province, China.[3] Yicaris' discovery is notable because its age suggests that true crustaceans already existed as far back in time as Early Cambrian, much earlier than other fossils known from the Middle and Late Cambrian. Its closest living relatives are believed to be cephalocaridans.[4]
| Yicaris Temporal range: | |
|---|---|
| |
| Holotype specimen | |
 | |
| Artist's reconstruction of Yicaris dianensis | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Clade: | Pancrustacea |
| Genus: | †Yicaris Zhang et al., 2007 |
| Type species | |
| †Yicaris dianensis Zhang et al., 2007 | |
Etymology
Description
Yicaris' body consists of a cephalothorax covered by a head shield and limb-bearing segments.[3]
Out of the thirty-four specimens examined, six consecutive growth stages are known, the smallest one being 460 μm while the largest fossil, though fragmentary, reaches 1.8 mm long.[3]
Yicaris is also notable for the leaf-like structures on its limbs called epipodites. The developmental origin of epipodites is thought to be enigmatic, but Yicaris' discovery shows that early crustaceans already possessed a set of three epipodites on their limbs. This structure is considered important due to its potential significance in the evolution of wings in insects, which evolved from within Pancrustacea.[3]
Notes
- Abbreviations: at, antenna(e); cs, cephalic shield; le, lateral eye(s); ma, mandible(s); mx, maxillula and maxilla; ta, trunk appendage(s).
