Name: Meganeura
(large nerved).
Phonetic: Meg-ah-neur-ah.
Named By: Charles Brongniart - 1885.
Classification: Arthtropoda, Insecta,
Odonatoptera, Protudonata, Meganeuridae.
Species: M. brongniarti, M. monyi,
M.
vischerae.
Type: Carnivore/Insectivore.
Size: Over 75 centimeter wingspan.
Known locations: Western Europe. Specifically
Commentry in France and Bolsover in Derbyshire, England.
Time period: End of Carboniferous.
Fossil representation: Well preserved specimens.
First
discovered in France in 1880, Meganeura is one
of the largest known
flying insects to ever exist. Although superficially similar to a
dragonfly, Meganeura and others like it are
generally referred to as
griffinflies, due to morphological differences between them and the
dragonflies.
It
is generally considered
that the maximum potential size of an insect is dictated by how much
oxygen is available for respiration. The oxygen content of our
atmosphere today is typically 21% of the total gases, but back in
the Carboniferous it was much higher at up to 35%. Insects like
Meganeura breathe through a system of tracheal tubes
that carry oxygen
directly into their internal tissues. A higher amount of oxygen in
the atmosphere would supply a passive boost to these tissues with no
effort on the part of Meganeura allowing for the
larger growth.
Falling oxygen levels after this period would mean that the giant
insects simply did not have enough oxygen to maintain their size,
resulting in either the evolution of smaller forms, or outright
extinction of the larger.
Meganeura
is likely to have
hunted and fed in much the same way as dragonflies do today, although
its larger size may suggest that many more creatures could have been on
the menu for it. Aside from other invertebrates potential prey may have
also included small amphibians that were rapidly evolving to
terrestrial life.
Further reading
- Les insectes fossiles des terrains primaires. Coup d'oeil rapide sur
la fauna entomologique des terrains pal�ozo�ques. - Bulletin de la
Soci�t� des Amis des Sciences Naturelles de Rouen 21(3):50-68. - C.
Brongniart - 1885.
- The engineering of the giant dragonflies of the Permian: revised body
mass, power, air supply, thermoregulation and the role of air density.
- Journal of Experimental Biology. 221 (19). - Alan E. R. Cannell -
2018.
- Palaeozoic giant dragonflies were hawker predators. - Scientific
Reports. 8 (1): 12141. - Andr� Nel, Jakub Prokop, Martina Pecharov�,
Michael S. Engel & Romain Garrouste - 2018.