Researchers from the University of Cambridge have discovered a fossil of the earliest echinoderm, similar to a starfish. The find sheds light on the origin of this marine species.
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 us recall that sea lilies, or crinoids (lat.Crinoidea), are 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.
An exceptionally well-preserved fossil, named Cantabrigiaster fezouataensis, has been discovered in the Moroccan Antiatlas mountain range. Its feathery, lace-like limbs froze in time about 480 million years ago.
The discovery, reported in Biology Letters, records the early stages of animal evolution during the Ordovician biodiversity leap. 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.
Modern starfish are part of the family of echinoderms, which, while lacking 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.
After examining the fossil, scientists concluded that Cantabrigiaster only had a key or axial body part, the alimentary groove that 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.