The mystery of fossils

This organism is called a Euglenid, it combines features of many different creatures. Euglenids are a group of aquatic single-celled eukaryotes (cells contain a nucleus and a shell). Energy is obtained both through photosynthesis, such as in plants, and through consumption by other living things, such as animals.. They diverged from other eukaryotes about a billion years ago. Throughout their existence on Earth, their fossils are very limited.

An international team of scientists says they have found ancient euglenid fossils hidden in a “massive paper trail” of previously published scientific research. Simply put, we saw them more than once, we just didn’t know who they were. How was it?

For many years, shell-like fossils were mistaken for worm eggs, algal cysts (a cyst is a protective shell that forms when adverse conditions occur), or fern spores, in part because of the small circular “ribs” inside them. But all these versions are not confirmed. The fossils did not fit into any taxonomic category, so in 1962 scientists named them Pseudoschizaea Turtles.

Their similarities have been confusing experts for years because these fossils cover a huge period of time, from almost half a billion years ago to the present day.

Andreas Koutsodendris, who studies microscopic fossils at Heidelberg University in Germany, says that when he examines lake cores in Greece, he regularly comes across fossils of these thin-walled oval life forms.

Their biological relationships have never been clarified. In fact, cysts are frequently mentioned in colleagues’ publications, but no one has been able to definitively determine their nature.
– says Kutsodendris.

There was a development in 2012

Paleontologists Bas van de Schootbrugge and Paul Strother are trying to identify some puzzling microfossils from sediments dating back to the Triassic-Jurassic boundary about 200 million years ago. They noticed that round, ribbed cysts could be euglenid. Because there’s another weird thing about euglenids. When these organisms become stressed, they wrap themselves in a protective cyst that resembles a three-dimensional fingerprint and enter a state of rest.

Light microscopic images of euglenoid cysts on the Triassic-Jurassic boundary / Photo: Bas van de Schutbrugge

Some of the microfossils we encountered bore a slight resemblance to cysts of Euglena, a modern representative described by Slovak colleagues. The problem is that there was only one publication in the world that made this claim:
– recalls Paul Strother, who worked at Boston College.

To find out whether they were right, Strother and Bas van de Schootbrugge, now at Utrecht University, teamed up with paleontologist colleagues from the US and UK to examine nearly 500 literature sources on Pseudoschizaea-like fossils.

These fossils have had different names over the years, so the situation is more complicated than it seems.. Using advanced microscopic techniques, they determined the structure of these cysts. “The ultrastructure of the cysts surprised us a lot., – says paleontologist Wilson Taylor from the University of Wisconsin-Eau Claire. – The structure of the wall is unlike anything known. The ribs are part of the wall structure, not decoration, as in pollen and spores. The layered wall structure also differs markedly from many other freshwater green algae.“.

Researchers are trying to coat live euglena algae in the lab, but in reality they already have something to fall back on. A YouTube video created by microscope enthusiast Fabian Weston from Australia appears to demonstrate exactly this process.

Fabian unknowingly provided important evidence. He is probably the only person on the planet who has seen Euglena cysts under a microscope.
Strother says.

A rare process called insistance, that is, the formation of protective cysts: Video

Now that researchers have established a possible deep life chronology for euglenids, Strother hopes it will make it easier for scientists to recognize older specimens, perhaps even those that “reach the root of the eukaryotic tree of life.” Scientists say that it is perhaps possible for these organisms to survive and survive all the extinctions on the planet thanks to their ability to exist.