Scientists have discovered extremely rare fossil trails left

by a suckerfish feeding along a lake bottom.

You would never suspect a sagebrush desert in Wyoming to be

famous for its fish. But 50 million years ago Fossil Butte National Monument was

a balmy freshwater lake. The fossils there are abundant, varied and look

good enough to eat…with a heavy helping of tartar sauce.

Amidst all these beautiful fossils, Emory University

paleontologist Anthony Martin is most excited about a little cluster of lines and

squiggles in the rock, a trail made in sediment by an extinct fish. Though bones

are abundant at Fossil Butte, traces left by living fish are rare (only about a

dozen have been identified at Fossil Butte) and this particular trail, described in PLoS One, is the rarest

of the rare: suckerfish mouth traces.

The trace has two wavy lines where fins had touched the

bottom and oval squiggles.

“The oval impressions stayed roughly in the center

of the wavy lines and slightly overlapped one another,” says Martin. “I

realized that these marks were probably made by the mouth as the fish fed along

the bottom.”

Martin is unwilling to say it’s the first fossil sucker imprint, but he says he’s read a lot about fish

trace fossils and this is the only sucker marks he’s seen.

This fossil is special in another way.  Scientists usually can’t link a trace fossil

to the animal that made it.  But there’s

only one fish species in Fossil Butte that ate off the bottom; Notogoneus osculus.

Martin isn’t the only Emory scientist working on the sucker

marks. Disease ecologist Gonzalo Vazquez-Prokopec measured the fossil using special

analysis and determined that the N.

osculus who left the imprints was 18 inches long.

Geographer Michael Page created an interactive Web site

where visitors can get up close and personal with the rare trace fossil.

Image: Suckerfish traces and the fish that left them, Anthony

Martin