Strange creature 'sealed' in rock for 478 million years: The ancestor of many species

An ancient stone slab in Morocco has preserved intact creatures that could fill an important evolutionary gap .

In a study just published in the scientific journal Nature Communications, a team of authors led by Dr. Lorenzo Lustri from the University of Lausanne (Switzerland) searched for the ancestral creature of today's very popular group of arthropods. such as: spiders, scorpions, horseshoe crabs.

Portrait of a creature that is the ancestor of many modern arthropods - (Photo: NATURE COMMUNICATIONS).

Modern scorpions, spiders and horseshoe crabs belong to a vast lineage of arthropods that appeared on Earth nearly 540 million years ago, at the beginning of the Cambrian period.

'More precisely, they belong to a subphylum of creatures with claws used specifically for biting, grasping prey or injecting venom, called chelicerae. But what are the ancestors of this particular group?' - Dr. Lustri raised the question.

This question has puzzled paleontologists since the study of ancient fossils began.

Many anamorphic organisms of the Cambrian and subsequent Ordovician periods have been found, but none have previously shared enough similarities with the modern species mentioned above to be considered ancestors of the animals. this item.

Dr. Lustri's tip "struck gold" when he found the answer in an ancient stone tablet in Morocco.

Named Setapedites abundantis , the new species is an intermediate evolutionary step between the more primitive Cambrian and arthropods.

This creature is only 0.5-1cm long, swimming in the Ordovician seas 478 million years ago.

Its anatomical features provide details of the first evolutionary steps to form a distinct group of organisms called arthropods.

Therefore, it can be said that it is the missing ancestor of spiders, scorpions, horseshoes. in modern times.

Setapedites abundantis in the Ordovician sea - (Graphic image: NATURE COMMUNICATIONS).

The Cambrian period and then the Ordovician period were periods that witnessed the leaps in evolution of Earth's animals in the oceans.

Although most of this class of organisms was wiped out during mass extinctions, their descendants - with completely different evolutionary patterns - are the basis of today's animals.