A team of researchers has discovered a new species of arthropod, a relative of today’s spiders or scorpions, which dates back to 450 million years and that it was perfectly preserved in three dimensions in a material that looked like gold in a site in the state of New York.
This kind of conservation is due to the material in which it was found, iron pyrite (also known as ‘fool’s gold’), was “filling” or occupying the different parts of the body of the dead animal trapped in a sediment. to the point of giving the sensation that it is embalmed in gold.
The fossil has been found in a site in the aforementioned state of North America known as the ‘Beecher Trilobite Bed’, in which there is a large representation of fossil organisms in perfect condition because the iron pyrite maintained the shape of their bodies. after being buried in the sediment, giving rise to spectacular three-dimensional golden fossils.
The discovery is described this Tuesday in the journal Current Biology, where the new species is named ‘Lomankus edgecombei’, in honor of Greg Edgecombe, a paleontologist at the Natural History Museum in London considered one of the world’s leading experts on arthropods.
“In addition to their beautiful and striking golden color, these fossils are spectacularly preserved, it seems as if when the rock in which they are washed they would come to life and run away,” says one of the authors, Luke Parry, a researcher at the British University of Oxford.
The new fossil belongs to a group of arthropods called ‘megacheirans’, which are characterized by having a large leg or appendage in the front part of the body to capture their prey.
The researchers emphasize that ‘megacheirans’ like Lomankus were very diverse during the Cambrian (between 538 and 485 million years ago), but became extinct in the Ordovician period (between 485 and 443 million years ago).
The fossil offers valuable clues to better understand how arthropods developed these front appendages in order to control their environment and capture prey, until they became what we know today as the antennae of insects and crustaceans, and the pincers and fangs of spiders and scorpions.
“Today, there are more species of arthropods than any other group of animals on Earth, and part of the key to that evolutionary success is their highly adaptable head and appendages,” adds Parry.
While other megacheirans used their large first appendage to capture prey, in Lomankus the typical claws are much smaller, with three long, flexible, whip-shaped flagella at the end.
This suggests that the animal used its frontal appendage to perceive its surroundings, rather than to capture prey, so its lifestyle would have been very different from that of its older relatives from the Cambrian period.
In fact, the fossil appears to lack eyes, so that frontal appendage would have been essential for searching for food in the dark, low-oxygen environment in which it lived.
Pyrite is a very dense mineral, so fossils preserved in this material can be scanned for hidden details of their anatomy.
The technique by which this data is obtained is known as computed tomography and consists of rotating the specimen while thousands of X-ray images are taken that allow the fossil to be reconstructed in three dimensions.