BEIJING, Dec. 20 (Xinhua) -- An international team of paleontologists announced in Beijing on Thursday that they have found a very rare phoresy relationship in amber: a pseudoscorpion moving between nests by "hitchhiking" from a bird during the mid-Cretaceous period.

A phoresy relationship occurs when one organism lives on or near the body of another, but not as a parasite. The organism usually uses its host for transport.

A pseudoscorpion is an arachnid that resembles a true scorpion but does not have a stinger or a tail. The oldest known fossil pseudoscorpion dates back 380 million years ago. Today, more than 3,000 species of pseudoscorpions exist worldwide.

Some species of pseudoscorpions are known to be phoretic -- "riding along" by attaching to insects like beetles. However, this is the first time that a pseudoscorpion was found hitchhiking on a bird.

The amber in which the pseudoscorpion was trapped was found in a valley in northern Myanmar. The valley is known for harboring one of the most diverse arrays of animals from the Cretaceous period in the world.

The amber specimen measures about 25 mm in length, 13 mm in width and 3 mm in thickness. The pseudoscorpion trapped inside is attached to fragmentary feathers.

Compared with beetles, pseudoscorpions' usual hosts, birds can provide far more places to hide and cling to with their relatively larger bodies, said Xing Lida, a paleontologist from the China University of Geosciences in Beijing and lead author of the research.

The pseudoscorpion probably embarked on a bird-ride by holding on to a feather, he noted.

Ryan McKellar, a paleontologist with the Royal Saskatchewan Museum in Canada, is also on the team. He said that their findings show the phoresy relationship between pseudoscorpions and some ancient birds.

The feather found in the amber could be part of a bird's nest, McKellar added. It shows that pseudoscorpions could move between nests by hitchhiking on birds as early as the Middle Cretaceous period.

He said the findings would help scientists gain a better understanding of the behavior of pseudoscorpions in the past.

The findings were published in the latest English edition of the bi-monthly Chinese geological journal of Acta Geologica Sinica. Enditem