Evolution of insects

In an important example of co-evolution, a number of highly successful insect groups — especially the Hymenoptera (wasps, bees and ants) and Lepidoptera (butterflies) as well as many types of Diptera (flies) and Coleoptera (beetles) — evolved in conjunction with flowering plants during the Cretaceous (145 to 66 million years ago).

Concretions are stones with a fossil at the core whose chemical composition differs from that of the surrounding matrix, usually formed as a result of mineral precipitation from decaying organisms.

[14] Molecular analysis by Gaunt & Miles 2002 suggests that the hexapods diverged from their sister group, the Anostraca (fairy shrimps), at around the start of the Silurian period 440 million years ago - coinciding with the appearance of vascular plants on land.

[24] The earliest winged insects are from this time period (Pterygota), including the aforementioned Blattoptera, Caloneurodea, primitive stem-group Ephemeropterans, Orthoptera, Palaeodictyopteroidea.

This allowed giant forms of pterygotes, millipedes and scorpions to exist, making the newly arrived tetrapods remain small until the Carboniferous Rainforest Collapse.

[28] The Permian (299 to 252 million years ago) was a relatively short time period, during which all the Earth's major land masses were collected into a single supercontinent known as Pangaea.

[21]: 400 During this time, many of the species from the Carboniferous diversified, and many new orders developed, including: Protelytroptera, primitive relatives of Plecoptera (Paraplecoptera), Psocoptera, Mecoptera, Coleoptera, Raphidioptera, and Neuroptera, the last four being the first definitive records of the Holometabola.

Pangaea's large size limited the moderating effect of the global ocean; its continental climate was highly seasonal, with very hot summers and cold winters.

[42] However, there are a few exemptions, like in Eastern Europe: At the Babiy Kamen site in the Kuznetsk Basin numerous beetle fossils were discovered, even entire specimen of the infraorders Archostemata (i.e., Ademosynidae, Schizocoleidae), Adephaga (i.e., Triaplidae, Trachypachidae) and Polyphaga (i.e., Hydrophilidae, Byrrhidae, Elateroidea) and in nearly a perfectly preserved condition.

In the stages of the Upper Triassic representatives of the algophagous, or algae feeding species (i.e., Triaplidae and Hydrophilidae) begin to appear, as well as predatory water beetles.

The first primitive weevils appear (i.e., Obrienidae), as well as the first representatives of the rove beetles (i.e., Staphylinidae), which show no marked difference in physique compared to recent species.

This family Tilliardipteridae, despite the numerous 'tipuloid' features, should be included in Psychodomorpha sensu Hennig on account of loss of the convex distal 1A reaching wing margin and formation of the anal loop.

Species of the superfamily Chrysomeloidea are believed to have developed around the same time, which include a wide array of plant host ranging from cycads and conifers, to angiosperms.

Broad shallow seas advanced across central North America (the Western Interior Seaway) and Europe, then receded late in the period, leaving thick marine deposits sandwiched between coal beds.

A few of the fossil sites mentioned in the chapter Jurassic also shed some light on the early cretaceous beetle fauna (e.g. the Yixian formation in Liaoning, North China).

[29] Even with the insect fossils record in general lacking, the most diverse deposit being from the Fur Formation, Denmark; including giant ants and primitive moths (Noctuidae).

Pauropoda Diplopoda (millipedes) Chilopoda (centipedes) Symphyla Arachnida (spiders, scorpions and allies) Eurypterida (sea scorpions: extinct) Xiphosura (horseshoe crabs) Pycnogonida (sea spiders) Trilobites (extinct) In 2008, researchers at Tufts University uncovered what they believe is the world's oldest known full-body impression of a primitive flying insect, a 300 million-year-old specimen from the Carboniferous Period.

The earliest vertebrates on land existed 350 million years ago and were large amphibious piscivores, through gradual evolutionary change, insectivory was the next diet type to evolve.

Thysanura (silverfish) Odonata (dragonflies) Orthoptera (grasshoppers and crickets) Phasmatodea (stick insects) Blattaria (cockroaches) Isoptera (termites) Hemiptera (true bugs) Coleoptera (beetles) Hymenoptera (ants, bees, and wasps) Lepidoptera (butterflies and moths) Diptera (flies) Traditional morphology-based or appearance-based systematics has usually given Hexapoda the rank of superclass,[70] and identified four groups within it: insects (Ectognatha), springtails (Collembola), Protura and Diplura, the latter three being grouped together as Entognatha on the basis of internalized mouth parts.

Matters that have had a lot of controversy include Strepsiptera and Diptera grouped together as Halteria based on a reduction of one of the wing pairs – a position not well-supported in the entomological community.

The abdominal and thoracic segments in the earliest terrestrial ancestor of the insects would have been more similar to each other than they are today, and the head had well-developed compound eyes and long antennae.

If the ancestors of the other flying insects evolved the same habit of clasping the female and dragging her over their spermatophore, but posterior instead of anterior like the Odonata does, their genitals would come very close to each other.

And finally when looking at the three most primitive insects with aquatic nymphs (called naiads: Ephemeroptera, Odonata and Plecoptera), each order has its own kind of tracheal gills that are so different from one another that they must have separate origins.

If insects got their wings on land and not in water, which clearly seems to be the case, the tree canopies would be the most obvious place where such gliding structures could have emerged, in a time when the air was a new territory.

Gliding requires universal body modifications, as seen in present-day vertebrates such as some rodents and marsupials, which have grown wide, flat expansions of skin for this purpose.

The need to navigate through vegetation and to land safely would mean good muscle control over the proto-wings, and further improvements would eventually lead to true (but primitive) wings.

From this point on, the arms race could continue: the same predator/prey co-evolution which has existed as long as there have been predators and prey on earth; both the hunters and the hunted were in need of improving and extending their flight skills even further to keep up with the other.

The distant ancestor of flying insects, a species with primitive proto-wings, had a more or less ametabolous life-cycle and instars of basically the same type as thysanurans with no defined nymphal, subimago or adult stages as the individual became older.

The final body-structure was no longer achieved while still inside the egg, but continued to develop for most of a lifetime, causing a bigger difference between the youngest and oldest individuals.

Assuming that mature individuals most likely mastered their new element better than did the nymphs who had the same lifestyle, it would appear to be an advantage if the immature members of the species reached adult shape and form as soon as possible.