Fossil Friday: Abrupt Appearance of a Distinct Dragonfly Group

This Fossil Friday features a beautiful fossil dragonfly of the genus Wightonia from the Early Cretaceous (ca. 115 mya) Crato limestones of northeast Brazil. The length of the fore- and hind wings is 38 and 39 mm respectively. This genus belongs to the extinct family Aeschnidiidae that was very diverse in the Late Jurassic and Early Cretaceous periods. I photographed this specimen at a German trader collection in February 2007. It is almost complete, only the abdomen is missing and was likely bitten off by a predator. Typical for the family Aeschnidiidae is the very dense wing venation with extremely narrow triangles and reduced pterostigmata, as well as multiple anal loops and medial and radial supplements. This very distinct group of dragonflies appeared abruptly in the Upper Jurassic without any evidence of their characteristic wing venation coming into being by a gradual transformation from an ancestral generalized dragonfly wing venation.