Feb. 25 (UPI) -- Scientists at the University of Portsmouth in Britain have found the first fossil plant gum on record. The gum was found inside 110 million year old fossilized leaves.
Fluids produced by plants take the form of resins and gums. Though they look similar, they're quite different.
"The main difference is their chemical composition, resin is composed of toxic terpenoids and is not water-soluble," Portsmouth doctoral student Emily Roberts, who discovered the fossilized gum, told UPI in an email. "Whereas, gum is composed of polysaccharides and is water-soluble. Visually they are indistinguishable -- which is why chemical confirmation is essential!"
When they set out to analyze the chemical composition of the ancient fossilized leaves, unearthed from the Crato Formation in Brazil, they expected to discover the spectral signatures of the resin's chemical components.
Instead, researchers discovered the spectral signature of plant gum -- the first evidence of fossilized plant gum.
The discovery, described this week in the journal Scientific Reports, overturns the assumption that plant gums can't survive fossilization.
The ancient gum was produced by an extinct member of the Welwitschiaceae plant family that lived during the Cretaceous period. Today, there is just one living Welwitschiaceae species. The modern Welwitschia plant lives in Africa's Namib Desert, one of the harshest environments on Earth.
While the ancient leaves aren't directly related to the modern Welwitschia plant, scientists suspect the two species are distant relatives.
"Today's Welwitschia produces gum," Leyla Seyfullah from the University of Vienna told UPI in an email. "So finding fossil leaves containing gum that may be a distant relative of today's Welwitschia is remarkable as if the fossil leaves are distant relatives. This would mean that gum production has been a feature of this group for at least 115 million years."
"Even if the leaves are not closely related to today's plants -- we do not know what the plant with the fossil leaves looked like as we, so far, only have the isolated leaves -- it means that we have the first proof that gum production in plants really extends back into the fossil record significantly," Seyfullah said.
Through followup research, scientists hope to better understand how exactly the gum became fossilized. Additionally, researchers plan to search for even older evidence of plant gums, as well as other types of fossilized plant fluids, or exudates.
"We want to know how far back in the fossil record different kinds of exudates date back," Roberts said. "This may tell us about the timing and environments of the evolution of different chemical pathways in plants, and perhaps give us insights as to why they originally evolved and how they have fared through time, and from that we can speculate about their potential future."
