Alien goldfish turned out to be an extinct species of molluscs

(ORDO NEWS) — Researchers from the UK and Canada seem to have finally managed to classify the ancient animal Typhloesus wellsi, also known as the “alien goldfish”. It is most likely that this is an extinct species of gastropod mollusk that lived on Earth over 300 million years ago.

Many types of fossils with unique and sometimes highly bizarre body shapes, appendages, fins, or internal arrangements are difficult to classify scientifically.

Finding their correct location on the phylogenetic (evolutionary) tree is hampered by the absence of any close analogues from organisms now living on Earth.

However, in recent years, scientists have managed to reduce the number of “unidentified” fossils, most of which are found in lagerstettes – special burials of well-preserved fossils.

In burials of this type, organisms retain not only the hard parts of the skeletons, but also traces of soft tissues. All thanks to an oxygen-free environment with a minimum number of bacteria, which delays the decomposition process.

Typhloesus wellsi is just one of these mysterious animals that lived more than 300 million years ago, during the Carboniferous period. The first fossils were found in 1973 in Bear Gulch Limestone in Montana, USA.

Since then, scientists have discovered several dozen samples, but they have not been able to accurately classify the animal for almost 50 years.

Alien goldfish turned out to be an extinct species of molluscs 1
Typhloesus wellsi showing a radula-like organ. (b) Elemental map showing possible traces of muscle tissue phosphating (red for carbon, green for phosphorus). Close-up (c) and details (d) of a radula-like organ

Because of its unique body structure, T. wellsi has been nicknamed the “alien goldfish”. Outwardly, the animal really remotely resembles a fish no more than nine centimeters long, but without gills, eyes, anus, chord or shell.

The only prominent feature that allowed T. wellsi to move in the water column is the horizontal tail fin.

Alien goldfish turned out to be an extinct species of molluscs 2
Anatomical diagrams and artistic reconstruction of Typhloesus wellsi

A pair of scientists from the University of Cambridge (Great Britain) and the Royal Ontario Museum (Canada) decided to once again carefully study the samples of the “goldfish” stored in the Royal Museum.

Exploring the internal structure of T. wellsi , the authors of the work discovered a completely new feature – a serrated structure in the intestines of the animal. It is a ribbon with two rows of 20 teeth curved back in the creature’s foregut.

This structure and arrangement of the organ led the researchers to suggest that T. wellsi was an active predator and hunted by throwing this ribbon into the surrounding water and capturing prey with it, just like lizards do. A similar organ is found in modern mollusks and is called the radula.

Thus, the authors of the study believe that the “alien goldfish” is nothing more than a Middle Paleozoic pelagic (that is, living in the water column, far from the bottom) gastropod mollusk.

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