Starfish-like fossil shows the evolution of a species in action

The starfish prototype found in the fossil shares similarities with both sea lilies and

modern starfish. It is the missing link for scientists trying to piece together its early evolutionary history.

Let's remind, sea lilies, or crinoids (lat.Crinoidea), is one of the classes of echinoderms. About 700 species are known in the world, in Russia - 5 species. These bottom animals have a body in the form of a cup, in the center of which there is a mouth, and a corolla of branching rays - tentacles - extends upward.

By Richard Ling (User: Rling) - Own work, CC BY-SA 3.0

An exceptionally well-preserved fossil,named Cantabrigiaster fezouataensis, was discovered in the Moroccan Anti-Atlas mountain range. Its feathery, lace-like limbs froze in time about 480 million years ago.

The discovery reported in Biology Letters, captures the early stages of animal evolution duringthe time of the leap in Ordovician biodiversity. Scientists can now use the find as a template to study evolutionary processes. Namely, the transition from a simpler form of animal existence to the complexity of their contemporaries.

Cantabrigiaster fezouataensis from the Lower Ordovician (Tremadoca) Fezouata Shale, Zagora, Morocco. Credit: Yale University Meeting

Modern starfish are part ofthe family of echinoderms, which, although they do not have a backbone, are one of the groups of animals closest to vertebrates. The origin of starfish has eluded scientists for decades. But the new species is so well preserved that its body can finally be mapped in detail and its evolution can be understood.

Reconstruction of Cantabrigiaster fezouataensis by Madmeg. Credit: Madmeg.

After studying the fossil, scientists came to the conclusion thatin Cantabrigiaster, only a key or axial part of the body was present, the alimentary groove, which guides food along each of the starfish's arms. All other off-axis parts of the hull appeared much later.

The study authors plan to expand their work in the search for early echinoderms.

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