Meganisoptera

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Meganisoptera
Temporal range: Pennsylvanian-Lopingian
Meganeurites gracilipes restoration.webp
Reconstruction of Meganeurites gracilipes
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Superorder: Odonatoptera
Order: Meganisoptera
Martynov, 1932
Families
Synonyms

Meganisoptera is an extinct order of large dragonfly-like insects, informally known as griffenflies or (incorrectly) as giant dragonflies. The order was formerly named Protodonata, the "proto-Odonata", for their similar appearance and supposed relation to modern Odonata (damselflies and dragonflies). They range in Palaeozoic (Late Carboniferous to Late Permian) times. Though most were only slightly larger than modern dragonflies, the order includes the largest known insect species, such as the late Carboniferous Meganeura monyi and the even larger early Permian Meganeuropsis permiana , with wingspans of up to 71 centimetres (28 in). [1]

Contents

The giant Upper Carboniferous dragonfly relative, Meganeura monyi, attained a wingspan of about 680 millimetres (27 in). . Meganeura monyi au Museum de Toulouse.jpg
The giant Upper Carboniferous dragonfly relative, Meganeura monyi , attained a wingspan of about 680 millimetres (27 in). .

The forewings and hindwings are similar in venation (a primitive feature) except for the larger anal (rearwards) area in the hindwing. The forewing is usually slenderer and slightly longer than the hindwing. Unlike the true dragonflies, the Odonata, they had no pterostigmata, and had a somewhat simpler pattern of veins in the wings.

Most specimens are known from wing fragments only; with only a few as complete wings, and even fewer (of the family Meganeuridae) with body impressions. These show a globose head with large dentate mandibles, strong spiny legs, a large thorax, and long and slender dragonfly-like abdomen. Like true dragonflies, they were presumably predators.

A few nymphs are also known, and show mouthparts similar to those of modern dragonfly nymphs, suggesting that they were also active aquatic predators. [3]

Although sometimes included under the dragonflies, the Meganisoptera lack certain distinctive wing features that characterise the Odonata. Grimaldi & Engel 2005 point out that the colloquial term "giant dragonfly" is therefore misleading, and suggest "griffenfly" instead.

Size

Scale model of a meganisopteran. Meganeuramodell.jpg
Scale model of a meganisopteran.

Controversy has prevailed as to how insects of the Carboniferous period were able to grow so large. The way oxygen is diffused through the insect's body via its tracheal breathing system (see Respiratory system of insects) puts an upper limit on body size, which prehistoric insects seem to have well exceeded. It was originally proposed in Harlé (1911) that Meganeura was only able to fly because the atmosphere at that time contained more oxygen than the present 20%. This theory was dismissed by fellow scientists, but has found approval more recently through further study into the relationship between gigantism and oxygen availability. [4] If this theory is correct, these insects would have been susceptible to falling oxygen levels and certainly could not survive in modern atmosphere. Other research indicates that insects really do breathe, with "rapid cycles of tracheal compression and expansion". [5] Recent analysis of the flight energetics of modern insects and birds suggests that both the oxygen levels and air density provide a bound on size. [6]

A general problem with all oxygen related explanations of giant griffenflies is the circumstance that very large Meganeuridae with a wingspan of 45 cm also occurred in the Upper Permian of Lodève in France, when the oxygen content of the atmosphere was already much lower than in the Carboniferous and Lower Permian. [7]

Bechly 2004 suggested that the lack of aerial vertebrate predators allowed pterygote insects to evolve to maximum sizes during the Carboniferous and Permian periods, maybe accelerated by an "evolutionary arms race" for increase in body size between plant-feeding Palaeodictyoptera and meganeurids as their predators.

Families and genera

These families belong to the order Meganisoptera: [8]

These genera belong to the order Meganisoptera, but have not been placed in families: [8]

Notes

  1. The model in this photograph incorrectly depicts pterostigmata on the wings.

Related Research Articles

<span class="mw-page-title-main">Carboniferous</span> Fifth period of the Paleozoic Era, 359–299 million years ago

The Carboniferous is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period 358.9 Ma, to the beginning of the Permian Period, 298.9 Ma. In North America, the Carboniferous is often treated as two separate geological periods, the earlier Mississippian and the later Pennsylvanian.

The Pennsylvanian is, on the ICS geologic timescale, the younger of two subperiods of the Carboniferous Period. It lasted from roughly 323.2 million years ago to 298.9 million years ago. As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain by a few hundred thousand years. The Pennsylvanian is named after the U.S. state of Pennsylvania, where the coal-producing beds of this age are widespread.

<span class="mw-page-title-main">Odonata</span> Order of insects that includes the dragonflies and damselflies

Odonata is an order of predatory flying insects that includes the dragonflies and damselflies. The two groups are distinguished with dragonflies usually being bulkier with large compound eyes together and wings spreaded up or out at rest, while damselflies are usually more slender with eyes placed apart and wings folded together along body at rest. Adult odonates can land, but rarely walk.

<span class="mw-page-title-main">Dragonfly</span> Predatory winged insects

A dragonfly is a flying insect belonging to the infraorder Anisoptera below the order Odonata. About 3,000 extant species of dragonflies are known. Most are tropical, with fewer species in temperate regions. Loss of wetland habitat threatens dragonfly populations around the world. Adult dragonflies are characterized by a pair of large, multifaceted, compound eyes, two pairs of strong, transparent wings, sometimes with coloured patches, and an elongated body. Many dragonflies have brilliant iridescent or metallic colours produced by structural coloration, making them conspicuous in flight. An adult dragonfly's compound eyes have nearly 24,000 ommatidia each.

<span class="mw-page-title-main">Damselfly</span> Suborder of insects

Damselflies are flying insects of the suborder Zygoptera in the order Odonata. They are similar to dragonflies but are smaller and have slimmer bodies. Most species fold the wings along the body when at rest, unlike dragonflies which hold the wings flat and away from the body. Damselflies have existed since the Jurassic, and are found on every continent except Antarctica.

<span class="mw-page-title-main">Aquatic insect</span> Insect that lives in water

Aquatic insects or water insects live some portion of their life cycle in the water. They feed in the same ways as other insects. Some diving insects, such as predatory diving beetles, can hunt for food underwater where land-living insects cannot compete.

<i>Meganeura</i> Extinct genus of insects

Meganeura is a genus of extinct insects from the Late Carboniferous. They resembled and are related to the present-day dragonflies and damselflies, and were predatory, with their diet mainly consisting of other insects. The genus belongs to the Meganeuridae, a family including other similarly giant dragonfly-like insects ranging from the Late Carboniferous to Middle Permian. With a wingspan about 65–75 cm (2.13–2.46 ft), M. monyi is one of the largest-known flying insect species.

The most recent understanding of the evolution of insects is based on studies of the following branches of science: molecular biology, insect morphology, paleontology, insect taxonomy, evolution, embryology, bioinformatics and scientific computing. It is estimated that the class of insects originated on Earth about 480 million years ago, in the Ordovician, at about the same time terrestrial plants appeared. Insects are thought to have evolved from a group of crustaceans. The first insects were landbound, but about 400 million years ago in the Devonian period one lineage of insects evolved flight, the first animals to do so. The oldest insect fossil has been proposed to be Rhyniognatha hirsti, estimated to be 400 million years old, but the insect identity of the fossil has been contested. Global climate conditions changed several times during the history of Earth, and along with it the diversity of insects. The Pterygotes underwent a major radiation in the Carboniferous while the Endopterygota underwent another major radiation in the Permian.

<span class="mw-page-title-main">Insect wing</span> Body part used by insects to fly

Insect wings are adult outgrowths of the insect exoskeleton that enable insects to fly. They are found on the second and third thoracic segments, and the two pairs are often referred to as the forewings and hindwings, respectively, though a few insects lack hindwings, even rudiments. The wings are strengthened by a number of longitudinal veins, which often have cross-connections that form closed "cells" in the membrane. The patterns resulting from the fusion and cross-connection of the wing veins are often diagnostic for different evolutionary lineages and can be used for identification to the family or even genus level in many orders of insects.

<span class="mw-page-title-main">Coal forest</span> Land type during the late Carboniferous and Permian times

Coal forests were the vast swathes of swamps and riparian forests that covered much of the land on Earth's tropical regions during the late Carboniferous (Pennsylvanian) and Permian periods. As plant matter from these forests decayed, enormous deposits of peat accumulated, which later became buried and converted into coal over the subsequent eras.

<i>Namurotypus</i> Extinct genus of dragonfly-like insects

Namurotypus is an extinct genus of griffinfly with a single described species Namurotypus sippeli. It inhabited the large swamps of the Carboniferous period. Namaurotypus had a 15 cm long forewing and did not have secondary male sex organs as in modern dragonflies.

<span class="mw-page-title-main">Pseudostigmatidae</span> Family of damselflies

The Pseudostigmatidae are a family of tropical damselflies, known as helicopter damselflies, giant damselflies, or forest giants. The family includes the largest of all damselfly species. They specialize in preying on web-building spiders, and breed in phytotelmata, the small bodies of water held by plants such as bromeliads.

<span class="mw-page-title-main">Geological history of oxygen</span> Timeline of the development of free oxygen in the Earths seas and atmosphere

Before photosynthesis evolved, Earth's atmosphere had no free oxygen (O2). Small quantities of oxygen were released by geological and biological processes, but did not build up in the atmosphere due to reactions with reducing minerals.

<span class="mw-page-title-main">Carboniferous rainforest collapse</span> Extinction event at the end of the Moscovian in the Carboniferous

The Carboniferous rainforest collapse (CRC) was a minor extinction event that occurred around 305 million years ago in the Carboniferous period. It altered the vast coal forests that covered the equatorial region of Euramerica. This event may have fragmented the forests into isolated refugia or ecological "islands", which in turn encouraged dwarfism and, shortly after, extinction of many plant and animal species. Following the event, coal-forming tropical forests continued in large areas of the Earth, but their extent and composition were changed.

<span class="mw-page-title-main">Respiratory system of insects</span>

An insect's respiratory system is the system with which it introduces respiratory gases to its interior and performs gas exchange.

Sinomeganeura is an extinct genus of griffinfly in the family Meganeuridae and containing a single species Sinomeganeura huangheensis. The species is known only from Late Carboniferous, Namurian stage, Tupo Formation near the village of Xiaheyan in Ningxia Hui Autonomous Region, China.

<span class="mw-page-title-main">Tarsophlebiidae</span> Extinct family of flying insects

The Tarsophlebiidae is an extinct family of medium-sized fossil odonates from the Upper Jurassic and Lower Cretaceous period of Eurasia. They are either the most basal member of the damsel-dragonfly grade ("anisozygopteres") within the stem group of Anisoptera, or the sister group of all Recent odonates. They are characterized by the basally open discoidal cell in both pairs of wings, very long legs, paddle-shaped male cerci, and a hypertrophied ovipositor in females.

<i>Mazothairos</i> Extinct insect genus

Mazothairos is an extinct genus of very large insect from the Carboniferous period. It was a member of the order Palaeodictyoptera. Although it is only known from very fragmentary remains from a single fossil, it is estimated to have had a wingspan of about 56 centimeters (22 in), making it one of the largest-known insects, only being rivaled in size by the largest members of the order Meganisoptera, such as Meganeura and Meganeuropsis.

Bojophlebia is an extinct genus of winged insect from the Pennsylvanian period of the Czech Republic. It includes only a single species, Bojophlebia prokopi, and is the only member of the family Bojophlebiidae. Bojophlebia prokopi was first described in 1985 by Jarmila Kukalová-Peck, who originally described it as a large mayfly-like insect. This original interpretation has since been rejected. Most recently, B. prokopi has been treated as a member of the infraclass Hydropalaeoptera, which also includes the Odonatoptera and Panephemeroptera. Bojophlebia is considered a sister group of all other members of the Hydropalaeoptera. A fossil that was described as a nymph of Bojophlebia is now considered to be a separate taxon, Carbotriplura kukalovae. The original description interpreted structures such as eyes and antennae, however these structures cannot be confirmed after restudy, although this may be an example of over-interpretation by Kukalová-Peck, as has happened with other extinct insects such as Carbotriplura and Gerarus.

References

  1. Grimaldi & Engel 2005, p. 175.
  2. Tillyard 1917, p. 324: "No Dragonfly at present existing can compare with the immense Meganeura monyi of the Upper Carboniferous, whose expanse of wing was somewhere about twenty-seven inches."
  3. Hoell, Doyen & Purcell 1998, p. 321.
  4. Chapelle & Peck 1999, pp. 114–115: "Oxygen supply may also have led to insect gigantism in the Carboniferous period, because atmospheric oxygen was 30-35% (ref. 7). The demise of these insects when oxygen content fell indicates that large species may be susceptible to such change. Giant amphipods may therefore be among the first species to disappear if global temperatures are increased or global oxygen levels decline. Being close to the critical MPS limit may be seen as a specialization that makes giant species more prone to extinction over geological time."
  5. Westneat et al. 2003: "Insects are known to exchange respiratory gases in their system of tracheal tubes by using either diffusion or changes in internal pressure that are produced through body motion or hemolymph circulation. However, the inability to see inside living insects has limited our understanding of their respiration mechanisms. We used a synchrotron beam to obtain x-ray videos of living, breathing insects. Beetles, crickets, and ants exhibited rapid cycles of tracheal compression and expansion in the head and thorax. Body movements and hemolymph circulation cannot account for these cycles; therefore, our observations demonstrate a previously unknown mechanism of respiration in insects analogous to the inflation and deflation of vertebrate lungs."
  6. Dudley 1998: "Uniformitarian approaches to the evolution of terrestrial locomotor physiology and animal flight performance have generally presupposed the constancy of atmospheric composition. Recent geophysical data as well as theoretical models suggest that, to the contrary, both oxygen and carbon dioxide concentrations have changed dramatically during defining periods of metazoan evolution. Hyperoxia in the late Paleozoic atmosphere may have physiologically enhanced the initial evolution of tetrapod locomotor energetics; a concurrently hyperdense atmosphere would have augmented aerodynamic force production in early flying insects. Multiple historical origins of vertebrate flight also correlate temporally with geological periods of increased oxygen concentration and atmospheric density. Arthropod as well as amphibian gigantism appear to have been facilitated by a hyperoxic Carboniferous atmosphere and were subsequently eliminated by a late Permian transition to hypoxia. For extant organisms, the transient, chronic and ontogenetic effects of exposure to hyperoxic gas mixtures are poorly understood relative to contemporary understanding of the physiology of oxygen deprivation. Experimentally, the biomechanical and physiological effects of hyperoxia on animal flight performance can be decoupled through the use of gas mixtures that vary in density and oxygen concentration. Such manipulations permit both paleophysiological simulation of ancestral locomotor performance and an analysis of maximal flight capacity in extant forms."
  7. Nel et al. 2008.
  8. 1 2 "The Paleobiology Database, order Meganisoptera" . Retrieved 2019-10-17.

Bibliography