The sophisticated eye structure of a 160 million-year-old marine arthropod (Dollocaris ingens) is described in a study published in Nature Communications this week. The study gives insight into the ecology of the species and the evolutionary history of arthropod vision.
Direct evidence of how ancient animals could perceive their environment is rare because internal eye structures are almost never fossilized.
Jean Vannier and colleagues examine exceptionally-well preserved fossils of D. ingens from southeast France, using scanning electron microscopy and energy dispersive X-ray spectroscopy to visualise the structure of the eyes and other internal organs. They find that the large eyes, which make up nearly a quarter of the length of the animal’s entire body, each consist of roughly 18,000 lenses - more than are found in most current arthropods except dragonflies. The authors also find that the internal eye structures share features with those of current insects and crustaceans.
The species’ eyes, raptorial legs, and stomach contents all suggest that D. ingens was an ambush predator of small crustaceans living in relatively shallow waters.