Palaeodictyoptera
| Palaeodictyoptera | ||||||||
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Illustration of Stenodictya lobata , Gerarus longicollis , Dieconeura arcuata, and Eubleptus danielsi |
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| Temporal occurrence | ||||||||
| Carbon to Permian | ||||||||
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| Systematics | ||||||||
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| Scientific name | ||||||||
| Palaeodictyoptera | ||||||||
| Goldenberg , 1877 |
The Palaeodictyoptera are an extinct order of insects .
features
They were medium to very large insects. The smallest known species was Eubleptus danielsi with a wingspan of 30 mm. The largest species belong to the paleozoic giant insects and are only exceeded in size by a few primeval dragonflies. Mazothairos enormis is said to have reached a wingspan of possibly up to 560 mm. However, only one isolated tergite of this species has actually come down to us, the size was only estimated on the basis of analogy in species with a similar physique. Actually preserved fossils, especially from species of the Homoiopteridae family , reached wing spans of 340 mm. The body of the animals was elongated. On the second and third thoracic segment there were two pairs of wings that were very similar to one another. In the resting position, the wings were carried spread apart from the body (as with the recent large dragonflies ), they could neither be folded up over the back nor folded backwards. Instead of cross veins, the wings had a dense network of (mostly pentagonal) small cells between the straight or slightly curved veins, this primitive type of wing veining is called "Archaedictyon". But some Permian representatives of the order had anatomically more modern wings with fewer veins. The wings were not flat, but like those of recent dragonflies and mayflies, stiffened like corrugated cardboard by kinks ("corrugation"). In contrast to these orders, however, intercalary veins never appeared in the Palaeodictyoptera. In the anatomically more primitive representatives, the fore and hind wings overlap strongly in living animals; this no longer occurs in modern insects. It is assumed that the animals therefore fly straight ahead quickly, but were very difficult to maneuver.
A rudimentary third pair of wings on the anterior thoracic section, the prothorax, is particularly noticeable and present in all species . When fully developed, these Protorax wings had the same veining and the same fine structure as the normal wings, so their homology with these can hardly be doubted. In many species they are reduced to narrow hem-like edge plates that can sometimes have thorns, but they are never completely absent. Even when fully trained, their size never reached more than 5% of the total wing area. Whether the prothorax wings could have been movable in some species is controversial in research. An aerodynamic meaning, similar to a tail unit on an aircraft, seems entirely plausible. The prothorax wings are also found in other primeval insects such as the geroptera belonging to the dragonfly stem line , so they are a plesiomorphic feature.
The mouthparts sat next to two long antennae on the head of the animals. These are transformed into a peculiar proboscis in all species, which consisted of five parts, the mandibles , maxillae and the needle-shaped hypopharynx . On the maxilla there were long palps (buttons), which in the anatomically original species were still articulated like legs (the animal therefore looked as if it had four pairs of legs). The labrum had pillow-shaped widened glosses and paraglons , with which the trunk was presumably supported during the suction process. Normally articulated legs with a different number (two to five) of tarsal limbs sat on the thorax , in some species the legs are reshaped in such a way that the animals primarily hold on to them, but could only walk poorly (similar to recent large dragonflies). The elongated, cylindrical abdomen consisted of ten segments (plus the rudimentary remainder of the eleventh). At the end there were two tail threads ( cerci ) that could reach enormous lengths. A third tail thread ( terminal filum ) is always missing. Female Archaeodictyoptera possessed a severely sclerotized, short and curved ovipositor with which they could presumably lay eggs in plant tissue. Instead, the male animals wore long appendages at the end of their abdomen, analogous to the genital feet of male mayflies.
development
Paleodictyoptera larvae have been found in fewer numbers than adults, but enough significant fossils are available to get an idea of the development. The larvae were then flattened animals with broad lateral appendages on the prothorax and abdomen. The wing sheaths protruded obliquely backwards in young larvae; in older larvae they gradually migrated to the side. They sat on the body with a narrow base and were probably mobile in life. The mouthparts of the larvae corresponded perfectly to those of the adults. Various suspicions that the animals were in the adult stage, i. H. as a winged animal, skinned or had a winged subimaginal stage, cannot be proven by fossil finds.
Occurrence and way of life
Almost all fossil Palaeodictyoptera were found in deposits that were close to the equator at that time when they were deposited; it was obviously a tropical, warmth-loving relationship. Most of the finds come from coal mining areas, and the carbonic hard coal forests were obviously a preferred habitat. About 140 species from 21 families have become known from the middle Upper Carboniferous ( Westfalium ) in Central Europe. Famous sites are in France (e.g. Commentry, Montceau-les-Mines) and the Czech Republic. Particularly well-preserved finds from the porch brickworks are known from Germany ; the first description of the order was made by the paleontologist Friedrich Goldenberg based on material from the Saarland coal field. The best finds from Permian representatives come from the USA (Elmo in Kansas). There are also finds from landscapes further away from the equator at that time, but they are considerably poorer. Species from three families were discovered in Siberia, and only one family each from Argentina, Tasmania and China.
From the habitat, from the physique and from very rare fossils with preserved intestinal filling, one concludes that the Palaeodictyoptera were plant suckers. This is entirely plausible for all representatives, but naturally not really demonstrable. In addition to plant juices, pollen and immature pollinaria in the carbonic flora seem to have been the main nutritional basis for the animals. Most of the time it is assumed that they were specialized phytophagi of the Cordaites and giant whiskers and other fern plants that made up the "trees" of the coal forests.
lifespan
A representative of the order, the Delitzschala bitterfeldensis found in East Germany , is the oldest flying insect found, this species lived in the younger Lower Carboniferous, on the border with the Upper Carboniferous. Among the carbonic insects, the order was one of the richest in species, although the individual densities were probably mostly low. Numerous species have only been found in a single specimen, of many of them only an isolated wing, even of well-documented species there are hardly more than ten to twenty finds. After a flowering in the Upper Carboniferous, most species became extinct during mass extinction at the base of the Permian. The early Permian fauna represented an impoverished section of the Carboniferous, hardly any new families were added, a total of only 13 species are known. Later, modified forms with peculiarly narrow wings were created, which presumably resembled recent small dragonflies in flight style. Some late representatives from Siberia showed modified fore wings with only a few veins and strongly regressed hind wings (family Eukulojidae). The order, which was already very poor in species at the time, probably fell victim to the serious mass extinction at the end of the Permian . Isolated reports of Triassic species (described from Kyrgyzstan and Thuringia) are very doubtful, the finds were assigned to different orders by other scientists.
The reason for the extinction of the Palaeodictyoptera is usually assumed to be a decline together with the tree-shaped ferns of the coal forests, which were probably their essential basis of life. In the increasingly arid Permian, these were pushed back to a few refuges near the equator and eventually died out due to competition from conifers (naked species). Some scientists also see the predation by dragonfly-like a reason for the decline of order.
Systematics
The Palaeodictyoptera form together with the also extinct orders Diaphanoptera , Megasecoptera and Permothemistida the superorder Palaeodictyopteroidea . It is the only completely extinct group of insects. The peculiar proboscis of the Palaeodictyoptera was common to all of these orders, so there is hardly any doubt about their common descent (monophyly). Many scientists consider the order Palaeodictyoptera to be paraphyletic itself. In their opinion, only the anatomically more original representatives are summarized here, which cannot be assigned to one of the other orders by a special characteristic. The entire hierarchy is summarized together with the trunk groups of dragonflies and mayflies as " Palaeoptera " or "Altflügler" because all of these groups lacked the wing joint with which the Neoptera or new winged can fold their wings on the abdomen. The Palaeoptera probably do not form a monophyletic community of descent.
swell
- Alexandr P. Rasnitsyn & Donald LJ Quicke: History of Insects. Kluwer Academic Publishers (Springer) 2001. 544 pp. ISBN 1-4020-0026-X
- Elke Gröning & Carsten Brauckmann (2005): New reconstruction drawings of selected paleozoic arthropods (flying insects, arachnids and arthropleura). - Virgo - Bulletin of the Entomological Association Mecklenburg, 8 (1): 21-25. ( PDF )
Individual evidence
- ^ Frank M. Carpenter (1983): Studies on North American carboniferous insects 7: The structure and relationships of Eubleptus danielsi (Palaeodictyoptera). Psyche 90: 81-95.
- ^ Robin J. Wootton & Jarmila Kukalova-Peck (2000): Flight adaptations in Palaeozoic Palaeoptera (Insecta). Biological Reviews of the Cambridge Philosophical Society 75: 129-167.
- ^ Robin J. Wootton (1972): Nymphs of Palaeodictyoptera (Insecta) from the Westphalian of England. Palaeoentomology 15 (4): 662-675.
- ↑ Jarmila Kukalova-Peck & Stewart B. Peck (1976): Adult and Immature Calvertiellidae (Insecta: Palaeodictyoptera) from the Upper Paleozoic of New Mexico and Czechoslovakia. Psyche 83 (1): 79-93. download
- ^ Roy J. Beckemeyer & Joseph D. Hall (2007): The entomofauna of the Lower Permian fossil insect beds of Kansas and Oklahoma, USA. African Invertebrates 48 (1): 23-39
- ^ Conrad Labandeira & TL Phillips (1996): Insect Fluid-Feeding on Upper Pennsylvanian Tree Ferns (Palaeodictyoptera, Marattiales) and the Early History of the Piercing-and-Sucking Functional Feeding Group. Annals of the Entomological Society of America, 89 (2): 157-183.
- ^ Carsten Brauckmann, Brigitte Brauckmann, Elke Gröning (1994): The stratigraphical position of the oldest known Pterygota (Insecta. Carboniferous, Namurian) Annales de la Société Géologique de Belgique 117 (Hommage à Maurice Streel) Fascicule 1: 47-56.
- ↑ Olivier Béthoux, Sebastian Voigt, Jörg W Schneider (2010) A Triassic palaeodictyopteran from Kyrgyzstan. Palaeodiversity 3: 9-13.
- ↑ Dimitry E. Shcherbakov (2011): The alleged Triassic palaeodictyopteran is a member of Titanoptera. Zootaxa 3044: 65-68.