When we think of fossils, we tend to imagine the strong, sturdy bones of dinosaurs and the hard, calcified shells of ammonites. Most of us do not picture the delicately preserved petals of an ancient flower.
Fossilized flowers are very rare, but in a study published in the journal Nature Scientific Reports, researchers in Berlin and Vienna identified a 40-million-year-old flower, preserved in amber resin, by extracting its pollen.
"In general, plant inclusions in amber are rarer than animal inclusions," Eva-Maria Sadowski, who led the study, told Newsweek. "For Baltic amber, only 1 to 3 percent of all inclusions are of botanical origin. This means finding a plant inclusion in amber that is exquisitely preserved and as large as the flower of this study is exceptional."
The flower's size is particularly unusual. It is the largest known amber-preserved flower fossil in the world, measuring over 1 inch in diameter. That might not sound like much, but most flower fossils rarely exceed 0.4 inches.
This particular flower grew in the Baltic forests of Northern Europe. "Although [this forest] is a famous amber deposit, we still know little about its vegetation and climate," Sadowski said. "Each new specimen is like a piece of a puzzle which adds new knowledge to the picture of this palaeo-ecosystem."
Fossilization of a plant or small animal in amber is called amberization. "It is not well understood how this process takes place," Sadowski said. "However, we know that several factors are crucial in this process, such as the resin chemistry—not every resin will turn into amber—the temperature, pressure and sedimentation."
Amber is formed from tree bark and acts as a sealant for any cracks in the tree's trunk and branches. Early on during the amberization process, the resin must block out any oxygen so that microbes cannot start to decay the flower locked inside. "During this process, the resin chemistry is crucial: Depending on the resin properties, it may act as a barrier for microbes," Sadowski said.
The amber specimen in question was first described in 1872 and was given to the Prussian Geological Survey, which is now the Federal Institute for Geosciences and Natural Resources (BGR) in Berlin-Spandau, Germany. Sadowski was unaware of the specimen until her colleague, Dieter Weyer, told her about an amazing, enormous amber flower in their collection.
"I was not even aware that they had an amber collection," she said. "So I asked the curator, Angela Ehling of the BGR collection, if I could come to see their collection, and there I found the specimen of this study.
"The preservation of the specimen and its pollen is extraordinary. It is also very striking to have a flower preserved in amber—which is already a rare case—which was right at anthesis and which provided enough pollen for extracting it," Sadowski said.
Anthesis is the point at which a flower opens for the first time, when the pollen is still fairly fresh on the flower's anthers. By extracting this pollen, Sadowski and her colleague Christa Hoffman were able to determine which modern-day species the specimen was most closely related to.
When the fossil was first described 150 years ago, it was named Stewartia kowalewskii, with the second part of the name referring to the man who owned it. However, the new pollen analysis revealed that the flower had more in common with the flower genus Symplocos, which includes modern-day horse sugar and Asiatic sweetleaf. This similarity prompted a renaming of the specimen to Symplocos kowalewskii.
"Flower fossils of Symplocos are generally rare," Sadowski said. "For now, there are only two confirmed fossil flowers of this genus, which are not from amber. So each fossil provides new information on how this genus looked like in its geological past."
Sadowski said she believes that the flower belonged to a conifer plant. It is likely to have grown in the forested habitats of the amber forest, although it may have also been found in swampy areas.
"The study provides us with new insights into forests of the late Eocene [epoch] in Europe and how they looked during that time," Sadowski said. "It also helps us to draw conclusions about the climate in the past and how it changed compared to today."
The Baltic forests are located in northern central Europe, stretching across Denmark, Germany, Poland and Sweden. The climate here can get fairly cold, but plant fossils from 30 million to 40 million years ago indicate that the forest used to be warm and humid.
"[The study] also gives us an idea about the distribution patterns of plant taxa/lineages in the past and how this distribution changed until today," Sadowski said. "For example, we found many plant taxa from Baltic amber which have affinities with plants from modern East and Southeast Asia, including the flower fossil of this study, and which do not occur in Europe today."
In future studies, Sadowski will continue to analyze ancient plant specimens from this era to find out more about what plant life might have looked like during this period. "I will continue to assemble these pieces of a puzzle," she said.
Do you have an animal or nature story to share with Newsweek? Do you have a question about fossils? Let us know via nature@newsweek.com.
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Pandora Dewan is a Senior Science Reporter at Newsweek based in London, UK. Her focus is reporting on science, health ... Read more
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