An exceptionally well-preserved Eocene dolichopodid fly eye: function and evolutionary significance.

Area of Science:

• Paleontology
• Entomology
• Evolutionary Biology

Background:

• Exceptionally preserved Eocene dolichopodid fly eyes in Baltic amber offer a unique window into ancient insect anatomy.
• Understanding the evolution of compound eyes is crucial for comprehending insect visual systems.

Purpose of the Study:

• To investigate the detailed structure of fossilized insect eyes from the Eocene epoch.
• To determine the earliest evidence for the neural superposition compound eye.
• To analyze the optical capabilities of ancient insect eyes.

Main Methods:

• Microscopic examination of exceptionally preserved Eocene dolichopodid fly eyes in Baltic amber.
• Analysis of ommatidia structure, including rhabdomere arrangement.
• Optical analysis of the fossilized eye system.

Main Results:

• Detailed preservation of Eocene fly eyes at micrometre and submicrometre levels.
• Identification of an open rhabdom with a trapezoidal arrangement of seven rhabdomeres, characteristic of neural superposition eyes.
• Evidence suggests the neural superposition compound eye existed as early as 45 million years ago (Ma).
• Optical analysis indicates a sophisticated and efficient visual system in the fossilized eyes.

Conclusions:

• The neural superposition compound eye, a complex visual system, was present in flies at least 45 million years ago.
• The detailed structure of the fossilized ommatidia supports their function as neural superposition eyes.
• Fossil insect eyes demonstrate sophisticated optical designs early in evolutionary history.