Laurasia
Guides
Petaluridae
petaltails, graybacks
Petaluridae is a relict family of dragonflies (Anisoptera) representing one of the most ancient lineages of extant dragonflies, with fossil records dating to the Jurassic period over 150 million years ago. The family comprises 11 extant species in five genera, divided into two major clades: a Laurasian clade (Tachopteryx, Tanypteryx) distributed in eastern and western North America and Japan, and a Gondwanan clade (Petalura, Phenes, Uropetala) found in Australia, New Zealand, and Chile. Petaltails are notable for their specialized larval habitats and extended development times, with most species persisting as independent lineages for 70–75 million years.
Willemia
Willemia is a genus of springtails (Collembola) in the family Hypogastruridae comprising at least 40 described species. Species occupy diverse habitats including sandy substrates (psammophily) and loam soils, with some inhabiting harsh environments such as polar regions, high mountains, and deserts. Phylogenetic studies indicate that psammophily is ancestral in this genus and has been lost twice independently, demonstrating that habitat specialization can be evolutionarily reversible. Species utilizing harsh environments tend to have low clade ranks and are concentrated on former Laurasian continents.