Bangkok, Thailand ? Scientists have identified two ancient reptiles that swam in icy waters off Australia 115 million years ago, researchers said Friday. They are among the first of their kind to be found from the period soon after the Jurassic era.

The discoveries – dubbed Umoonasaurus and Opallionectes – belonged to a group of animals called plesiosaurs, long-necked marine reptiles that lived during the time of the dinosaurs.

Researchers, led by paleontologist Benjamin Kear and a team from the University of Adelaide and South Australian Museum, identified the new species after piecing together fossils from 30 individuals collected from an opal mine in the past 30 years.

The team’s findings were recently published in both the international journal Paleontology and the online edition of Biology Letters, a periodical published by the prestigious Royal Society of London.