Fossil shows origin of stuffing your face

Flora Graham, editor, newscientist.com

(Image: Yie Jang, Yunnan University)

This multi-limbed creature is a Fuxianhuiid arthropod, and it's not waving, but eating. Some of those arms are actually mouthparts, the earliest ever seen.

Fuxianhuiids lived from 520 million years ago, roughly 50 million years before primordial land animals crawled from the sea. They had soft bodies, but their heads were covered in a hard shell, which has hidden the structures underneath in all fossils previously found. But now, thanks to an astonishingly rich new site in southern China, we have several specimens like the one pictured that were fossilised after losing their shells.

This has given researchers the first opportunity to examine the appendages on the creature's head, which turn out to be the earliest and simplest example of manipulative limbs used for feeding purposes.

The researchers reckon that fuxianhuiids adapted the limbs to push sediment into their mouths while grazing along the sea floor. They would then filter out the tasty morsels, such as traces of decomposed seaweed.

The revelation sheds light on the earliest moments of limb development in arthropods, which evolved into the insects, spiders and crustaceans we know today.

"Since biologists rely heavily on organisation of head appendages to classify arthropod groups, such as insects and spiders, our study provides a crucial reference point for reconstructing the evolutionary history and relationships of the most diverse and abundant animals on Earth," says Javier Ortega-Hern?ndez from the University of Cambridge, who was on the research team.

The fossils also revealed the oldest nervous system on record that extends beyond the head - a single nerve string.

"These fossils are our best window to see the most primitive state of animals as we know them - including us," says Ortega-Hern?ndez. "Before that there is no clear indication in the fossil record of whether something was an animal or a plant."

The fossils were found at a new site called the Xiaoshiba biota. It has proven stunningly rich in arthropod remains and even surpasses the bounty of the Chengjiang biota, says Ortega-Hern?ndez.

"More than 50 specimens of fuxianhuiids have been found in just over a year, whereas in previous areas considered fossil-rich, such as Chengjiang, it took years - even decades - to build up such a collection."

Journal reference: Nature, DOI: 10.1038/nature11874

Source: http://feeds.newscientist.com/c/749/f/10897/s/2910d0e9/l/0L0Snewscientist0N0Cblogs0Cshortsharpscience0C20A130C0A20Cfossil0Efuxianhuiid0Bhtml0Dcmpid0FRSS0QNSNS0Q20A120EGLOBAL0Qonline0Enews/story01.htm

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