Biology Reference
In-Depth Information
Although only a few fossil insects (such as Collembola) are known from
the lower Devonian, a massive radiation began sometime during the early
Carboniferous,
>
325 million years ago, and the pterygotes radiated into stem
groups of all major lineages, including ephemeroids, odonatoids, plecopteroids,
orthopteroids, blattoids, hemipteroids, and endopterygotes. Insects continued to
increase in diversity during the late Carboniferous and middle Permian (
Table 12.4
).
Insects are highly diverse and ancient arthropods (
Budd and Telford 2009
).
The Crustacea are considered the sister group of the Tracheata (
=
Myriapoda
+
Hexapoda or Insecta). Relatively advanced Crustacea are found in the Cambrian
(600mya), so it is assumed that tracheates were present by this time as well
(
Kukalova-Peck 1991
).
Labandeira et al. (1988)
showed that a bristletail
(Archaeognatha) from the Early Devonian resembles modern archaeogna-
thans. Arthropods apparently have been found on land since Devonian times
(
Table 12.4
). Two Collembola species found in the lower Devonian (400mya)
resemble recent Isotomidae and Neanuridae, suggesting that terrestrial arthro-
pods already had radiated in the Ordovician (
≈
500 mya).
Several extinct and extant orders of primitive insects have been found
in a diverse late-Paleozoic fauna (
Table 12.4
). During the Carboniferous,
which began 360mya, a diverse array of extinct and extant insects were pres-
ent, including the Diplura, Monura, Diaphanopterodea, Palaeodictyoptera,
Megasecoptera, Permothemistida, Ephemoptera (mayflies), Protodonata,
Paraplecoptera, Plecoptera (stoneflies), Orthoptera (grasshoppers and crickets),
Blattodea (cockroaches), Caloneurodea, Blattinopsodea, and Miomoptera.
During the Permian, which began
≈
285mya, additional extinct and extant
(underlined) insect groups are found in the fossil record, including Plecoptera
(stone flies), Embioptera (web spinners), Protelytroptera, Glosselytrodea,
Thysanoptera (thrips), Hemiptera (bugs and leafhoppers), Antliophora,
Mecoptera (scorpion flies), Diptera (true flies), Asmphiesmenoptera, Neuroptera
(lacewings, ant lions), Megaloptera (dobsonflies), and Coleoptera (beetles).
By the Triassic (245 mya), nearly all of the modern orders of insects are found
in the fossil record, including Lepidoptera (butterflies and moths), Trichoptera
(caddisflies), and Hymenoptera (bees and wasps). By the Jurassic (210 mya), many
recent families are present. Tertiary insects (65 mya) are essentially modern and
include genera nearly indistinguishable from living fauna.
There are
>
700,000 living species of living insects (estimates vary, with
some asserting that up to two million insects are currently present). The
orders Coleoptera (
>
300,000 named species), Lepidoptera (
>
120,000 species),
