Oldest Seahorses Found; Help Solve Mystery

The oldest seahorse fossils discovered to date have been uncovered in Slovenia, including this two-inch-long (five-centimeter-long) adult female Hippocampus sarmaticus fossil (left, and in an artist's reconstruction, right).

The 13-million-year-old finds, which include the only known extinct seahorse species, are shedding light on how the naturally weak swimmers managed to disperse around the world.

Researcher Jure Žalohar of Slovenia's University of Ljubljana first spotted a fossil in the water as he was washing his hands in a stream after a jog.

Žalohar and colleagues were originally investigating fossil insects in this area, so finding the fossil seahorses was "completely unexpected," he said.

The findings appeared online April 17 in the French-language journal Annales de Paleontologie.



This 13-million-year-old baby seahorse, with a head measuring just 5 millimeters (0.2 inch) long, is among the oldest seahorse fossils ever discovered, scientists said in April 2009.

Earlier seahorses likely lived in the temperate shallow coastal waters of the passageway between Europe and Africa that linked the Atlantic with the Indian Ocean until about 15 million years ago, the researchers say. That passageway would have helped the fish slowly spread around the globe.

They probably dwelled in dense beds of seagrass, where food--such as small crustaceans--was abundant. The seahorses' black flecks would have camouflaged them in the vegetation, which the fish also likely anchored themselves to using their prehensile tails.



Researchers TomazÿHitij (left) and Jure Žalohar (right) investigate plates of gray siltstone in Slovenia in an undated photo.

Stone plates like these contain the oldest fossils of seahorses ever found, and this region is the only known site with fossils of extinct seahorse species.

More fossil seahorses will likely be found in similar sediments in neighboring central European countries, Žalohar said in April 2009


These faint fossils of two juvenile seahorses, called Hippocampus slovenicus, are among the oldest seahorse fossils ever found, scientists said in April 2009.

The new finds suggest that the fish could have held onto floating clumps of seagrass for weeks or months with their prehensile tails. If caught in a current, these rafts of seagrass may have carried the seahorses as far as 160 miles (260 kilometers) in a month--possibly explaining how the poor swimmers were able to spread around the globe.



This baby Hippocampus sarmaticus seahorse fossil is roughly 1.3 inches (3.5 centimeters) long.

In a recent expedition, scientists found seahorse fossils of different ages living near each other, probably in what were once dense beds of seagrass.