Middle Jurassic insect mines on gymnosperms provide missing links to early mining evolution

Area of Science:

• Paleontology
• Insect Evolution
• Mesozoic Flora

Background:

• Insect herbivory, specifically leaf mining, is a significant ecological interaction.
• Fossil evidence for Jurassic leaf mining is scarce, creating a gap in understanding its evolutionary history.

Purpose of the Study:

• To investigate the earliest known fossil evidence of insect leaf mining from the Middle Jurassic.
• To document new damage types (DTs) and identify insect groups responsible for mining during this period.

Main Methods:

• Microscopic examination of 2014 plant specimens from the Daohugou locality.
• Categorization of herbivory using the functional feeding group-damage-type system.
• Photographic documentation and database creation of fossil mines.

Main Results:

• Identified 27 occurrences of mining on 14 specimens, representing eight new mine damage types (DTs).
• Mines were found on six genera of gymnosperms: bennettitalean, ginkgoalean, and pinalean.
• Likely insect miners include basal lineages of polyphagan beetles, monotrysian moths, and tenthredinoid sawflies.

Conclusions:

• Mid-Mesozoic mines are morphologically conservative, reflecting plant host anatomy more than phylogeny.
• The nutrition hypothesis, suggesting miners exploited nutrient-rich inner plant tissues, best explains mine evolution.
• This study provides crucial insights into insect feeding strategies and plant-insect interactions during the Jurassic.