When new islands appear above the surface of the ocean their colonization usually follows a standard pattern. The initial living things to grow there are plants, germinating from seeds and spores borne on the wind. The first animals are always insects, again because they can be blown on the wind from distant continents. The first vertebrates to arrive are the birds and pterosaurs, winged vertebrate creatures that are able to fly over the intervening ocean areas. Very often these winged creatures give up their powers of flight and take up a ground-dwelling existence, eating the plants and the insects on an island that is free from any dangerous predators.
The shorerunner is just such a pterosaur, found on one Pacific Ocean island group near the Equator, Kiribati. It lives mainly on the beach, running here and there catching other shore creatures, or pecking about in the ferny undergrowth for smaller reptiles and insects. It is also adept at climbing trees, using its long fingers and toes, and can run nimbly along branches using its useless wings for balance. The Kiribati islands are no more than about five million years old (dating back to the Early Pliocene, or Zanclean), suggesting that the shorerunner's ancestors must have arrived since that time. From the flying ancestor several species have developed to populate the groups of islands, all with slightly different shapes and sizes and differing eating habits.