Trilobite fossils in the study (Barrande, 1846). (Photo by Brigitte Schoenemann) Nature Research Courtesy of Photo
Beijing, August 14 (China News Network) (Reporter Sun Zifa) How did the principle of animal vision evolve? How have the eyes of ancient and living animals changed?
Trilobite right eye. (Photo by Brigitte Schoenemann) Nature Research Courtesy of Photo
According to a recent paleontological research paper published in Springer Nature's open access journal Science Reports, the internal structure of a fossil eye of a trilobite from 429 million years ago is almost identical to that of a modern bee.
This finding suggests that the visual principles of many modern insect and crustacean eyes are at least 500 million years old.
Trilobite left eye. (Photo by Brigitte Schoenemann) Nature Research Courtesy of Photo
Corresponding author Brigitte Schoenemann of the University of Cologne in Germany and Euan Clarkson of the University of Edinburgh in the United Kingdom collaborated to re-examine a fossil of Aulacopleura koninckii found in the Czech Republic in 1846 using digital microscopy. The fossil is 1-2 mm tall and has two raised semi-elliptical eyes on the back of the head, one of which has been ruptured. Some of the internal structures they reported are similar to those of many modern insects and crustaceans, including its visual unit called the small eye (35 microns in diameter), which contains photosensitive cells that gather around the transparent tube bundle of the sensory rod bundle.
Modern transparent crustacean shrimp. (Photo by Brigitte Schoenemann) Nature Research Courtesy of Photo
The authors argue that the dark rings that surround each visual unit are made up of pigment cells that act as a barrier between the visual units. Each visual unit has a thick lens on the surface, and the rest is a flat crystal cone through which the light passes before focusing on the rod beam.
The small size of the visual unit indicates that the trilobite fossil once lived in bright shallow waters and may be more active during the day, because the smaller diameter lens has a higher light capture efficiency in bright environments. There is a pigment cell barrier between the visual units, indicating that this trilobite once had mosaic vision, and each visual unit contributed a small part of the overall picture, similar to the compound eyes of many modern insects and crustaceans.
Trilobite fossils in the study (Barrande, 1846). (Photo by Brigitte Schoenemann) Nature Research Courtesy of Photo
The authors conclude that their findings suggest that the structure and function of many compound eyes have barely changed since the Paleozoic era (542 million to 252 million years ago), providing a new understanding of the ancient life of trilobites. (End)
Source: China News Network