Mazon Creek Fossil Fauna
Insects, Nymphs, and Wings
Our earliest record of winged insects appears in the Pennsylvanian at which time they already display advanced development and diversity. Views on insect origin and evolution remain speculative. Some insist that all insects can be traced to a myriapod-like ancestor (millipedes and centipedes), while others suggest a direct line to the crustaceans.
True cockroaches do not appear in the fossil record until the Late Mesozoic. The Carboniferous forms – which represent the majority of all known insects at the time, though less common in the Mazon Creek Fauna - lacked the ability to produce egg sacs as do their modern counterparts. Instead, they laid eggs directly in the soil. They are collectively known as Roachoids.
Fossil insect nymphs have been studied intensively by investigators seeking to determine the evolution of wings and flight muscles. The earliest true flying insects are from the Pennsylvanian and it is felt that modern nymphs may briefly repeat the development of these ancestors.
Wings comprise the majority of insect specimens and therefore the bulk of our knowledge of Paleozoic insects. In fact, the greater portion of the literature on all fossil insects is actually about fossil wings. The subject of the why and how of flight and wing development is still under debate.