Jovian (Jupiter Five)

The Jovians, a.k.a. Culture X, were a sapient reptilian species originating from outside the Sol System (the name "Jovian" being therefore a misnomer). They became extinct over five million years ago, although the cause of their extinction remains unknown.

In the 21st century, it was discovered that the Jupiter moon known simply as "Jupiter Five" is actually an enormous spaceship (about 30 km long) built by the Jovians, which brought them from their original world to the Sol System.

Biology
Jovians were large creatures, about four times the height of a man, which evolved on a low-gravity planet. They were reptilianoids with narrow heads, four arms and a long powerful tail that helped to support them, similar to a kangaroo's tail. They had gill slits on their necks and no nostrils.

History
Millions of years ago, Jovians arrived in the Sol System and placed their spaceship in orbit around Jupiter, where it would later become known as that planet's innermost satellite, Jupiter Five (i.e. the fifth Jovian moon to be discovered, after the four Galilean moons). Having evolved on a low-gravity world, the Jovians settled on both Mars and Mercury, but had no interest in Earth and Venus, as the gravity of those two planets was too strong for them. On Mars, they made peaceful contact with the insect-like Martians and both species lived together amicably until both became extinct over five million years ago. The cause of their extinction is unknown.

Appearances

 * "Jupiter Five", by Arthur C. Clarke (1953) (statue only)