Figure 4. Examples of Cambrian eyes within metazoan phyla from the Chengjiang Fauna.

The eyes are indicated by an arrow. (a) Lobopod Hallucigenia fortis (RCCBYU 10248, YU) has a pair of sessile eyes composed of at least two visual units (ommatidia), interpreted as pigment cups¹². (b) Vertebrate Haikouichthys ercaicunensis (HZ-f-12-127, YGSK) has a pair of eyes identified by Shu et al.¹⁶. (c) Mollusc Petalilium latus (158642, NIGPAS) with two camera-type eyes, which are attached by short stalks to the latero-ventral surface of the head³². (d) Bivalved arthropod Isoxys auritus with a pair of large eyes, projecting from the body and showing a flexible eye-stalk, the ommatidial lens distinguished by Schoenemann and Clarkson¹⁴. (e) Cambrian apex predator Anomalocaridids Amplectobelus sumbrachiata (ELRC 21002, NIGPAS) supposedly has a pair of enormous compound eyes with acute vision³⁰. (f) Trilobite Eoredlichia intermedia (158643, NIGPAS) eyes typically sessile, crescentic, with inflated palpebral lobe ridges running toward front of glabella. Scale bars: (a) 5 mm; (b–f) 1 cm. [Panel (a) courtesy of X.-G. Hou, Yunnan University, Kunming, China (YU); panel (b) courtesy of H.-L. Luo, Yunnan Institute of Geological Sciences, Kunming, China (YGSK); panel (c), (d), (e), (f) are from Nanjing Institute of Geology and Palaeontology, China (NIGPAS).]