New starfish-like fossil reveals evolution in action

Researchers from the University of Cambridge have discovered a fossil of the earliest starfish-like animal, which helps us understand the origins of the nimble-armed creature.

 Cantabrigiaster fezouataensis from the Lower Ordovician (Tremadocian) Fezouata Shale, Zagora Morocco  Credit: Collection of Yale University

The prototype starfish, which has features in common with both sea lilies and modern-day starfish, is a missing link for scientists trying to piece together its early evolutionary history. 

The exceptionally preserved fossil, named Cantabrigiaster fezouataensis, was discovered in Morroco’s Anti-Atlas mountain range. Its intricate design – with feathery arms akin to a lacework – has been frozen in time for roughly 480 million years.  

The new species is unusual because it doesn’t have many of the key features of its contemporary relatives, lacking roughly 60% of a modern starfish’s body plan.

The fossil’s features are instead a hybrid between those of a starfish and a sea lily or crinoid - not a plant but a wavy-armed filter feeder which fixes itself to the seabed via a cylindrical ‘stem’.

The discovery, reported in Biology Letters, captures the early evolutionary steps of the animal at a time in Earth’s history when life suddenly expanded, a period known as the Ordovician Biodiversification Event.

The find also means scientists can now use the new find as a template to work out how it evolved from this more basic form to the complexity of their contemporaries. 

“Finding this missing link to their ancestors is incredibly exciting. If you went back in time and put your head under the sea in the Ordovician then you wouldn’t recognize any of the marine organisms - except the starfish, they are one of the first modern animals,” said lead author Dr Aaron Hunter, a visiting postdoctoral researcher in the Department of Earth Sciences.

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Image: Cantabrigiaster fezouataensis from the Lower Ordovician (Tremadocian) Fezouata Shale, Zagora Morocco

Credit: Collection of Yale University

Reproduced courtesy of the University of Cambridge



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