Cretaceous gnetalean yields first preserved plant gum

Area of Science:

• Paleobotany
• Organic Geochemistry
• Biomolecular Paleontology

Background:

• Plant exudates like resin are found in the fossil record.
• Gums, being water-soluble polysaccharides, were presumed to degrade before fossilization.
• Visual similarity between gums and resins necessitates chemical analysis for differentiation.

Purpose of the Study:

• To chemically confirm the presence of preserved gum in fossil plant material.
• To investigate the potential for preservation of water-soluble biomolecules in the fossil record.
• To compare the chemical signature of fossil gum with extant relatives.

Main Methods:

• Chemical analysis of Welwitschiophyllum leaf fossils from the Early Cretaceous Crato Formation.
• Comparison of the chemical signature of fossil gum with extant Welwitschia gum and fossil resins.
• Analysis of geological context regarding water exposure during fossilization.

Main Results:

• First chemical confirmation of preserved gum in Early Cretaceous Welwitschiophyllum leaves.
• Fossil gum exhibits a chemical signature similar to extant Welwitschia gum.
• The preserved gum is chemically distinct from fossil resins.
• Preservation occurred despite the fossil leaves being exposed to water.

Conclusions:

• Water-soluble plant exudates (gums) can be preserved in the fossil record.
• This finding expands the range of biomolecules recognizable in fossils.
• The study provides a new avenue for understanding plant evolution and paleoecology through preserved exudates.