Scientists from the Federal University of Paraná (UFPR) recently revealed the discovery of a rare geological process, which led to the preservation of sea snake fossils, dating back around 400 million years.
Published in the Journal of South American Earth Sciences and published by the UFPR science portal, this finding deals with ancient echinoderms related to sea stars, known as ophiuroids.
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(Source: UFPR/Reproduction)
The fossils of these incredibly fragile creatures were located in rock samples from the Devonian Period collected in the Ponta Grossa region, in Paraná, in 2020.
The discovery is intriguing, as ophiuroids require exceptional conditions for fossilization to survive over millions of years. The samples studied were provided by four paleontological collections, including:
Paleontology Laboratory (Labpaleo) at UFPR;
Museum of Paleo and Geology at the University of Guarulhos (UNG) in São Paulo;
Paleontological Research Center at the Contestado University (UNC) in Santa Catarina;
Geological Museum of São Paulo.
The study revealed the presence of a dark, carbon-rich film on the fossils, the result of the carbonization of the viscera of these ancient marine beings.
This phenomenon allowed researchers to analyze in detail the anatomy of the species Encrinaster pontis It is Marginix notatus, both long extinct.
The process is rare and never observed in echinoderms, it occurs after burial, when the organic parts of an organism are compressed by the weight of the sediment.
It is most common in samples that contain substances such as chitin, keratin, lignin or cellulose, volatile elements of organic matter that are lost, leaving only carbon during fossilization.
Normally, only the hard parts of ophiuroid skeletons, such as spines and ossicles, are preserved, but the carbonization, in this case, preserved remains of the beings' soft parts.
This occurred shortly after the first weeks of burial, preventing the decomposition of the soft parts by bacteria in the sediment.
The exceptional discovery led the responsible researcher, Malton Carvalho Fraga, to propose the term “Ponta Grossa Konservat-Lagerstätte” to refer to these rocks from Paraná rich in ophiuroids and other fossil groups associates.
In addition to the high quality of preservation, some fossils reveal evidence of predation, offering a rare glimpse into the predators of these animals throughout Earth's history.
Ophiuroids lived in the polar sea that covered Paraná and other states in Brazil during the Devonian.
They fed on carcass remains and organic particles present in the sediment and water column, migrating to marine areas in search of food when necessary.
Most fossils from Paraná suggest that sea snakes were buried in the same place where they lived, mainly due to sediment expelled by large rivers in deltas.
This, according to the geologist, was facilitated by the presence of large volumes of fresh water in the sediments, which probably anesthetized the ophiuroids, preventing their escape from burial.
With the discovery, Paraná became recognized as the largest source of fossils of ophiuroids in South America, with hundreds of samples collected over the last century, mainly in the municipalities of Ponta Grossa and Jaguariaíva.
