The Petaltails of the family Petaluridae are apparently the most ancient of the extant dragonflies, having fossil members from as early as the Jurassic (over 150 million years ago). Modern petalurids include only 11 species, one of which, the Australian Petalura ingentissima, is the largest of living dragonflies, having a wingspan of up to 160 mm and a body length of over 100 mm. In the United States there are two species, one on either coast. The larvae live primarily in stream banks, mostly in burrows, but the larvae of the eastern U.S. species, Tachopteryx thoreyi, apparently live in depressions under wet leaves. The semi-aquatic habitat of the larvae makes the Petaltails unique in the modern dragonfly families.

Bibliography

Silsby, Jill. 2001. Dragonflies of the World. Smithsonian Institution Press, Washington D.C.