Brazilian scientists re-analyzed 296-million-year-old plant fossil, revealing well-preserved spore inside

Some new developments have been noted in a fossil older than a dinosaur. For the study, researchers evaluated a fossil discovered in Brazil, which was explained in detail within the journal Review of Palaeobotany and Palynology. The remains belonged to a brand new genus called Franscinella and the species Franscinella riograndensis, a prehistoric plant from Paraná Basin. Past examinations showcased that the plant fossil was preserved for nearly 296 million years at the time of discovery. The new study resolves a 50-year-old pursuit for experts.

50-year-old challenge

For the last five decades, experts have been trying to detect in-situ plant spores on Upper Paleozoic clastic rocks of Brazil, dated between 298.9 million years and 252.17 million years, according to Science Daily. Through the investigation, researchers not only detected elusive spores but also redefined what was previously classified as Lycopodites riograndensis into F. riograndensis. They also recorded the first instance of lycopodites with in-situ spores in the Permian strata of the Paraná Basin. They achieved the objective due to the way the fossil was preserved, along with the cutting-edge methodologies they applied in their evaluations. 

Startling revelations

After the initial discovery of the fossil, it was identified as Lycopodites riograndensis, according to SciTech Daily. They made the categorization based on the external features visible on the fossil, which included its shape and stem arrangement. It did not consider detailed anatomical and spore-level insights, which raised doubts about its accuracy. The fossil material was preserved in the Univates Paleontological Collection, when it was revisited by a team from the University of Vale do Taquari – Univates. Their goal was to use refined techniques to find out previously unknown anatomical and palynological details. These advanced techniques included scanning electron microscopy (SEM), vinyl polysiloxane silicone molding (VPS), and transmitted light microscopy. 

These techniques gave a better-than-ever view of the fossil's surface features and internal structures. As a result, the team detected isotomic branching of stems, trilete spores with verrucate ornamentation, qualities primarily associated with particular fossil lycopsids, and preserved tracheids in the vascular cylinder, which typically plays a pivotal role in identifying extinct plant species. The spores uncovered in the fossil were noteworthy, as nothing like it had been detected in fossil plants as old as this one. These pores stood apart, as they were present in the reproductive organs of the plant and were possibly in situ. It means that they were located and preserved in their original position.

These features clearly showcased that a taxonomic reclassification was the need of the hour. They concluded that the fossil belonged to a brand new genus and named its species F. riograndensis. Researchers typically classify fossil plants like the one evaluated in the study under the Lycopodites genus, as it belongs to the fossil group lycopodids. As more advanced technologies arrive, this classification will become more specific, just in the case of the aforementioned fossil. 

Connection to Permian

The features of the spores uncovered from the fossil aligned in morphology with the palynological genus Converrucosisporites. This spore genus is mostly present in Permian deposits of the Paraná Basin. These insights are crucial, as they connect the microfossil record (spores and pollen grains) to the macrofossil record (visible parts of plants). The connection can furthermore shed light on the features of past vegetation and ecosystems. In this particular case, researchers are hopeful they will find more about Permian plant communities.

These first-of-its-kind spores will be used by experts to showcase what kind of flora persisted in the Permian, and how vascular plants evolved. These findings may also reveal how herbaceous lycopsids were distributed across the Permian in Gondwana, as this is only the fifth known lycopod fossil, dating back to that time. Researchers will also contrast the insights with other similar records in other regions of the world for more information on the species.