Scholars from the University of Warsaw and the Polish Academy of Sciences elucidated the enigmatic coexistence of animal and plant life forms within the coastal sea shallows around 427 million years ago.
Their discovery unveiled the hitherto unknown occurrence of algae thriving alongside graptolites, extinct marine microorganisms.
An article featured in the journal “Acta Geologica Polonica” marks the culmination of nearly a decade’s worth of research on Silurian rocks, a period within the Paleozoic era dating back 444-419 million years, conducted in the western region of Ukraine by a team affiliated with the Faculty of Geology at the University of Warsaw.
The scientists concentrated on locations abundant in stromatoporoid layers, constructed by an enigmatic group of extinct organisms that dwelled on the seafloor. During the Paleozoic era, particularly in the Silurian and Devonian periods, stromatoporoids served as primary architects of the organic structures of that era, analogous to modern-day reefs.
Much to the scientists’ astonishment, it was revealed that the majority of the scrutinized layers resulted from the erosion of reefs during violent storms. “Perhaps the most intriguing revelation we encountered was the resemblance of certain sediments to those deposited by tsunamis. While the Silurian tsunamites of Podolia weren’t the initial fossil deposits ascribed to such a genesis, they swiftly emerged as among the foremost global examples of recording this type of phenomenon within sediments,” emphasized Prof. Stanisław Skompski, one of the contributors to the research.
Furthermore, what piqued the scientists’ interest were the strata nestled between the stromatoporoid layers, originating from exceedingly shallow-water coastal environments.
In that location, researchers discovered enigmatic sessile algae preserved in remarkable condition, adorned with attached epiphytic organism twigs. Professor Anna Kozłowska from the Institute of Paleobiology of the Polish Academy of Sciences aided in identifying them as graptolites. Graptolites represent an extinct animal group characterized by a rather unconventional structure, resembling slender twigs with short outgrowths known as tecs. Conversely, an epiphyte denotes a plant that grows on another plant, typically not adopting a parasitic lifestyle but utilizing another species for support.
“We managed to confirm the graptolite nature of the mysterious branches growing on algae, and thus demonstrate the co-occurrence of plant (algae) and animal (graptolite) forms,” said Prof. Skompski in an interview with Nauka w Polsce.
Two previously unknown forms were observed: Voronocladus dryganti and Podoliagraptus algaeoides, both named by the researchers. Professor Skompski highlighted that the alga’s name pays homage to Professor Danila Drygant from the Natural History Museum in Lviv, acknowledging his substantial contributions to the longstanding Polish-Ukrainian cooperation in geological research over many years.
According to Professor Skompski, the discoveries made during the nearly decade-long research significantly enhance our understanding of Silurian sediments deposited several hundred million years ago along the shoreline of the vast Eastern European continent, whose boundary traversed, among other regions, present-day Poland.
“The Silurian was an extremely important period for the evolution of life on Earth, as it was a time of expansion towards land of marine vegetation typical of shallow waters. The discovery of the co-occurrence of plant and animal forms is an important contribution to identifying the characteristics of this process,” concluded Prof. Skompski.
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