Palaeodictyopteroida: Megasecoptera

Megasecoptera

There are 22 families of megasecopterans and only about 35 known genera, so -- right out of the box -- we should be suspicious that the diversity of the group is undersampled and poorly understood.  

Like many other paleopterans, the megasecopterans had sucking mouthparts, which doesn't fit the usual party line about detritivory.  Instead, it is quite clear that the Megasecoptera were "plant vampires."  The suctorial wouth parts were used to pierce plant casings and extract high-quality plant materials, such as spores and pollen.  

Megasecoptera bore two pairs of wings (some very basal paleopterans had three), which are nearly of the same size.  The wings were held horizontally, as in dragonflies (Odonata, Anisoptera).  The wing bases tend to be very slender, as in damselflies (Odonata, Zygoptera).  The body is long and thin.  The illustrated Protohymen is rather stouter and shorter than a typical megasecopteran.   

During their relatively brief existence, the Megasecoptera were extremely succesful.  It has been estimated that this order accounted for 50% of the insect biomass in some locations.  This may be an overestimate, because Megasecoptera tended to be rather large.  Some reached almost unbelievable dimensions, with wingspans close to 100 cm.  As a result they are over-represented in the fossil record.  It has been suggested that insects of this size would be capable of soaring flight, like an albatross or large pterosaur.  

Links: ELMO INSECTS IN BRIEF, Insect Flight- Evolution