Scientists discover oldest starfish-like fossil

Fossil

Scientists from The University of Western Australia have uncovered the oldest starfish-like fossil, Cantabrigiaster Fezouataensis, which is the first ancestor of all starfish in the world.

The fossil was uncovered in Morocco and the discovery provides an insight into the evolution of starfish and other echinoderms such as sea lilies. The research has been published in the Royal Society.

Starfish and brittle stars, collectively known as Asterozoans, are a diverse and ecologically successful group of spiny-skinned echinoderms that first appeared in fossil records around 480 million years ago in the Ordovician period.

However, the evolution and origin of starfish and brittle stars and their relationship to the oldest echinoderms (from the Cambrian period) still remains somewhat of a mystery.

UWA scientists, in collaboration with researchers from the University of Cambridge and Harvard University, discovered the Cantabrigiaster fezouataensis.

Adjunct Research Fellow Aaron Hunter, from UWA’s School of Earth Sciences, said the researchers drew uponprevious research from WA Museum collections of living crinoids collected from deep water along the north-west WA coast.

“It was while looking at the arm structure of the living dried crinoid specimens that I realised the resemblance to the arm of Cantabrigiaster,” Dr Hunter said.

“This observation and discovery of a new fossil specimen allowed me to resurrect an idea from the 1960s that Asterozoans are descended from crinoids.

“Our analysis indicates that Cantabrigiaster is the earliest diverging stem-group for Asterozoans and therefore the earliest ancestor of all starfish-like animals discovered.”

Dr Hunter said the analysis also sheds light on potential origins of crown-group echinoderms living in today’s oceans relative to their Cambrian stem-group ancestors.

“The finding leads us one step closer to understanding how life on Earth evolved and how modern echinoderms came to exist,” he said.

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