Seahorse


Anatomical evidence, supported by molecular, physical, and genetic evidence, demonstrates seahorses are highly modified pipefish. The fossil record of seahorses, however, is very sparse. The best known and best studied fossils are specimens of H. guttulatus (though literature more commonly refers to them under the synonym of H. ramulosus), from the Marecchia River Formation of Rimini Province, Italy, dating back to the Lower Pliocene, about 3 million years ago. The earliest known seahorse fossils are of two pipefish-like species, H. sarmaticus and H. slovenicus from the coprolitic horizon of Tunjice Hills, a middle Miocene lagerstŠtte in Slovenia dating back about 13 million years.

Molecular dating finds that pipefish and seahorses diverged during the Late Oligocene. This has led to speculation that seahorses evolved in response to large areas of shallow water, newly created as the result of tectonic events. The shallow water would have allowed the expansion of seagrass habitats that selected for the camouflage offered by the seahorsesŐ upright posture. These tectonic changes occurred in the western Pacific Ocean, pointing to an origin there, with molecular data suggesting two later, separate invasions of the Atlantic Ocean. Read more ...




In the News ...


Ancient Pygmy Pipehorse Species Found -   National Geographic - May 10, 2012
Fossils of a new species of pygmy pipehorse - a relative of the seahorse - have been discovered in Slovenia, a new study says. Scientists discovered the 1-inch-long (2.5-centimeter-long) species dubbed Hippotropiscis frenki in a fossil-rich region called the Tunjice Hills, where the team also found the oldest known seahorse fossils in 2009. Pygmy pipehorses are thought to be an evolutionary link between seahorses and their close relatives, including pipefish and seadragons. The animals share so many features that at first study leader Jure Zalohar and colleagues thought the newfound fossils belonged to another type of ancient seahorse. Modern pygmy pipehorses also look and behave a lot like seahorses pygmy pipehorse males, for instance, care for their fertilized eggs in a special pouch.




Oldest Seahorses Found; Help Solve Mystery -   National Geographic - May 4, 2009
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.





Seahorse




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