Pollination of Cretaceous flowers

Area of Science:

• Paleontology
• Botany
• Entomology

Background:

• Insect pollination is crucial for angiosperm diversity and Cretaceous plant evolution.
• Direct fossil evidence of insect-pollinated angiosperms from the Cretaceous period is scarce.
• Existing Cretaceous pollination evidence primarily links insects with gymnosperms.

Purpose of the Study:

• To provide direct fossil evidence of insect pollination of angiosperms during the mid-Cretaceous.
• To investigate a specific fossil beetle and associated pollen from Burmese amber.
• To understand the co-evolution of insects and flowering plants.

Main Methods:

• Analysis of mid-Cretaceous Burmese amber containing a tumbling flower beetle, *Angimordella burmitina*.
• X-ray microcomputed tomography (micro-CT) to reveal beetle morphology and mouthparts.
• Confocal laser scanning microscopy to examine tricolpate pollen grains attached to the beetle.

Main Results:

• Discovery of *Angimordella burmitina* with numerous tricolpate pollen grains, indicative of eudicots.
• Identification of specialized beetle morphology for flower visitation and pollen feeding.
• Pollen grains exhibit characteristics of zoophilous (animal) pollination.

Conclusions:

• This finding provides the first direct evidence of beetle-angiosperm pollination in the mid-Cretaceous (99 Ma).
• Extends the known timeline of insect-angiosperm pollination associations by at least 50 million years.
• Supports the hypothesis of specialized insect pollination modes existing in eudicots during the Cretaceous.