124 mil­lion years

China Daily (Hong Kong) - - CHINA -

Age of the old­est fos­sil cray­fish found in China

“The an­cient cray­fish look like the mod­ern ones, but they also have body parts that dif­fer from each other, es­pe­cially the shape and num­ber of legs of the male.”

After an­a­lyz­ing the im­print of weeds, fish and shells in the fos­sils, Shen con­cludes that the an­cient cray­fish in China lived in fresh­wa­ter but not sea­wa­ter.

Pieces of fos­sil cray­fish were un­earthed in western Liaon­ing in the early 20th cen­tury, he said. Many of them were sent to Ja­pan be­cause at the time North­east China was oc­cu­pied by Ja­panese troops.

To study the fos­sils, Shen and two crus­tacean ex­perts from the United States, Rod Tay­lor and Frederick Schram, had to bor­row them from a mu­seum in Yoko­hama.

For years, Shen has searched for fos­sil cray­fish in Liaon­ing. He has gone to re­mote ar­eas, asked deal­ers for in­for­ma­tion and bought spec­i­mens from var­i­ous peo­ple.

He keeps a fos­sil of a cray­fish try­ing to catch a fish and an­other of a cray­fish ly­ing on its back. (Most fos­sil cray­fish are on their bel­lies.)

“Why all the cray­fish sud­denly dis­ap­peared from China around 100 mil­lion years ago is a mys­tery,” Shen said. “And the con­nec­tion of an­cient cray­fish in China and North Amer­ica is still to be found.”

In the 1920s, Ja­pan im­ported cray­fish to feed bull­frogs, and later in­tro­duced the species to China’s Yangtze River Delta.

The red crus­tacean has be­come a pop­u­lar food across China. Ac­cord­ing to a re­port from China’s Min­istry of Agri­cul­ture in June, the out­put of cray­fish last year reached 899,100 met­ric tons, mak­ing China the world’s largest pro­ducer. Nearly 5 mil­lion peo­ple are in­volved in the in­dus­try.

Some Chi­nese ex­perts dis­agree with Shen, in­sist­ing that cray­fish in fact orig­i­nated in North Amer­ica. Fang Xingx­ing, a re­searcher at Nan­jing Agri­cul­tural Univer­sity, said di­rect ev­i­dence of evo­lu­tion and more fos­sil cray­fish need to be pro­vided to prove that the species orig­i­nated in China.

Guo Jun con­trib­uted to this story.

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