Fossilised shrimp show earliest group behaviour

The conga was the world's first dance, it seems. A newly discovered caravan of crustaceans from half a billion years ago shows that group behaviour evolved not long after animals themselves.

Palaeontologists led by Hou Xian-Guang, of Yunnan University, China, discovered fossilised chains of up to 20 crustaceans linked head-to-toe, the earliest record of any collective animal behaviour and perhaps an adaptation to a migratory ocean lifestyle.

"It's showing that, 525 million years ago, we've got really quite sophisticated and potentially complex interaction between different animals," says Derek Siveter, of the University of Oxford, who analysed the fossil along with colleagues at the University of Leicester, UK.

They concluded that the undulating procession of ancient arthropods, each about 2 centimetres long, represents more than a quirk of fossilisation. Though none of their arms, legs or antennae survived a half billion years in stone, the animals probably interlocked appendages to stay together.

"We hypothesise that the chain was in the water column and it met its demise by whatever reason or forces, then it sunk to the bottom," he says. - ns