The flutterbirds are a diverse group of tubenoses that come in a number of different species, living in the Antarctic Tropical Rainforest (as well as other habitats of the continent), 100 million AD.
One group of Antarctic seabirds that fared particularly well in the new conditions were procellariiforms, such as shearwaters, fulmars, and albatrosses. Dating back to the Middle Paleogene (and possibly the Late Cretaceous), procellariiforms were almost exclusively pelagic (feeding in the open ocean) and bred mostly on islands in the Southern Hemisphere (especially around New Zealand), although some breeding grounds were as far north as the Caribbean and even on the northeastern tip of Greenland. They also wandered widely at sea during the nonbreeding season. Already capable of adapting to different climates, such forms as petrels remained and diversified as Antarctica gradually moved north, evolving to suit the changing conditions. They became the most varied and widespread group on the Antarctic continent, radiating to fill new evolutionary niches and becoming increasingly difficult to dislodge.
Now, in 100 million AD, the Antarctic continent boasts many species of bird. There are birds with long, narrow wings that soar over the land, smaller birds with short, broad wings that can maneuver easily in confined forests, and even flightless, ground-living birds. The majority of these are procellariiforms. The most widespread group of petrel descendants are flutterbirds.