13.1 Two of the major players in the story of Lake Annecy are green algae and crustacia, Daphnia and Copepods. Both are closely related to the origins of life on land. Land plants evolved from green algae, insects evolved from crustacean. Crustacea are part of a larger group the arthropods which include Trilobites, Myriapodes, Chelicerates, Crustaceans, and Insects.  Arthropods are defined by five characteristics, bilateral structure, segmented bodies, hard exoskeleton, jointed legs and multiples pairs of limbs. During the entire 300 million years of the Palezoic, Trilobites were one of the dominant life forms in the oceans, but were entirely wiped out during the Permian extinction. Nevertheless the Arthropods survived to this day, and now account for around 83 % of all known described species according to berkeley university’s excellent evolution website.

http://evolution.berkeley.edu/evolibrary/article/arthropods_intro_01

13.2 Based on genome sequencing data, it is estimated that the class of insects could have originated on Earth about 480 million years ago, in the Ordovician, at about the same time terrestrial plants appeared, indicating that a similar mutual relationship had evolved on land as between crustacean and algae in the oceans. However, the oldest definitive insect fossil, Rhyniognatha hirsti, is estimated to be much later at 407 to 396 Ma, during the early Devonian. This species already possessed dicondylic mandibles, a feature associated with winged insects, suggesting that wings may already have evolved at this time. Thus, the first insects probably appeared earlier, in the Silurian period. Like other insects of its time, Rhyniognatha presumably fed on plant sporophylls — which occur at the tips of branches and bear sporangia, the spore-producing organs. The earliest trees at this time, as mentioned above, were the lycophytes, which reproduced by spores at the tips of their branches. In 2012, researchers found the first complete insect in the Late Devonian period (382 to 359 Ma), in the Strud (Gesves, Belgium).

13.3 The Carboniferous (359 to 299 Ma) is famous for its wet, warm climates and extensive swamps of mosses, ferns, horsetails, and calamites. Remains of insects are scattered throughout the coal deposits, particularly of wings from cockroaches (Blattodea). In 1940 (in Noble County, Oklahoma), a fossil of Meganeuropsis americana represented the largest complete insect wing ever found.

13.4 The Pterygotes (winged insects) underwent a major radiation in the Carboniferous (356 to 299 Ma). When the first forests arose on Earth, new niches for terrestrial animals were created. Spore-feeders and others who depended on plants and/or the animals living around them would have to adapt too to make use of them. In a world with no flying animals, it must have been just a matter of time before some arthropods who were living in the trees evolved paired structures with muscle attachments from their exoskeleton and used them for gliding, one pair on each segment.

13.5 Insects that had evolved their proto-wings in a world without flying predators could afford to be exposed openly without risk, but this changed when carnivorous flying insects evolved. It is unknown when they first evolved, but once these predators had emerged they put a strong selection pressure on their victims and themselves. Those of the prey who came up with a good solution about how to fold their wings over their backs in a way that made it possible for them to live in narrow spaces would not only be able to hide from flying predators (and terrestrial predators if they were on the ground) but also to exploit a wide variety of niches that were closed to those who couldn't fold their wings in this way. And today the neopterous insects (those that can fold their wings back over the abdomen) are by far the most dominant group of insects.

13.6 The Endopterygota (insects that go through different life stages with metamorphosis) underwent another major radiation in the Permian (299 to 252 million years ago).

13.7 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).

13.8 During the 1940 British biologist JB Haldane wrote in his book What is Life? “The Creator would appear as endowed with a passion for stars, on the one hand, and for beetles on the other, for the simple reason that there are nearly 300,000 species of beetle known, and perhaps more, as compared with somewhat less than 9,000 species of birds and a little over 10,000 species of mammals. Beetles are actually more numerous than the species of any other insect order. That kind of thing is characteristic of nature.” Today we know there are more than 800,000 species of beetle and they represent around a quarter of all know species. Beetle fossils are abundant during the entire Early Cretaceous, and thus provide important clues to explore the co-evolutionary processes between beetles and angiosperms. These four beetle groups are important pollinators of angiosperms today, suggesting that their ecological association with angiosperms probably formed as early as in the Early Cretaceous.

13.9 However a 2007 study based on DNA of living beetles and maps of likely beetle evolution indicated that beetles may have originated during the Lower Permian, up to 299 million years ago. In 2009, a fossil beetle was described from the Pennsylvanian of Mazon Creek, Illinois, pushing the origin of the beetles to an earlier date, 318 to 299 million years ago into the end of the Carboniferous. At the same time the oldest known insect that resembles species of Coleoptera date back to the Lower Permian (270 million years ago).

13.10 Glaciations in Gondwana, triggered by Gondwana's southward movement, and the cooling and drying of the climate led to the Carboniferous Rainforest Collapse. Tropical rain forests fragmented and then were eventually devastated by climate change. As a consequence of the Mass Extinction at the border of Permian and Triassic, there is only little fossil record of insects including beetles from the Lower Triassic. Later, during the Late Triassic, mycetophagous, or fungus feeding species of beetle (i.e., Cupedidae) appear in the fossil record. 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 was also around the first time evidence of diverse freshwater insect fauna appeared.

13.11 There are many important sites from the Jurassic, with more than 150 important sites with beetle fossils, the majority being situated in Eastern Europe and North Asia. During the Jurassic there was a dramatic increase in the known diversity of family-level Coleoptera. This includes the development and growth of carnivorous and herbivorous species.

13.12 There are many fossils of beetles known from the Paleogene period, though the beetle fauna of the Paleocene epoch is comparatively poorly investigated. In contrast, the knowledge on the Eocene beetle fauna is very good. The reason is the occurrence of fossil insects in amber and clay slate sediments. Amber is fossilized tree resin, that means it consists of fossilized organic compounds, not minerals. Different amber is distinguished by location, age and species of the resin producing plant. For the research on the Oligocene beetle fauna, Baltic and Dominican amber is most important.

13.13Most extant orders of insects developed during the Permian period. Many of the early groups became extinct during the mass extinction at the Permo-Triassic boundary, the largest extinction event in the history of the Earth, around 252 million years ago. At that time around 30% of all insect species became extinct; this is one of three known mass insect extinctions in Earth's history. Given that the insects had flourished in a symbiotic relationship along with the rise of the great forests, it is not surprising that the Carboniferous Rainforest Collapse particularly impacted the insects. Nevertheless, the survivors of this event evolved in the Triassic (252 to 201 million years ago) to what are essentially the modern insect orders that persist to this day. Most modern insect families appeared in the Jurassic (201 to 145 million years ago).

13.14 Many modern insect genera developed during the Cenozoic that began about 65 million years ago; insects from this period onwards frequently became preserved in amber, often in perfect condition. Such specimens are easily compared with modern species, and most of them are members of extant genera.

13.15 The first butterflies are from the Upper Paleogene around 60 Ma, while most, like beetles, already had recent genera and species already existed during the Miocene, however, their distribution differed considerably from today's.

13.16 The most important sites for beetle fossils of the Miocene are situated in the warm temperate and to subtropical zones. Many recent genera and species already existed during the Miocene, however, their distribution differed considerably from today's. One of the most important fossil sites for insects of the Pliocene is Willershausen near Göttingen, Germany with excellently preserved beetle fossils of various families (longhorn beetles, weevils, ladybugs and others) as well as representatives of other orders of insects. In the Willershausen clay pit so far 35 genera from 18 beetle families have been recorded, of which six genera are extinct. The Pleistocene beetle fauna is relatively well known, who used the composition of the beetle fauna to reconstruct climate conditions in the Rocky Mountains and on Beringia, the former land bridge between Asia and North America.

13.17 So to return to the plants where terrestrial life started, the deal was simple. The plants supply the insects with all the food they need in the form of pollen and fallen leaves, and the insects carry off the plants spores to reproduce in ever wider locations. Perhaps this is why there are 800,000 species of beetle on the Earth: each new group of plants needs its own team of arthropods to get the job done.   So the land plants have solved all their evolutionary challenges by a) internal design of double vascular system, leaves and wood b) coopting the natural properties of water molecules and c) co-operating with other species, the insects. Thus they went forth and conquered. Within a couple of hundred million years of the first tentative, microbial steps on land with the humble liverwort, great continents had been conquered by mighty conifers and flowering trees. Good business model!

13.18 There is one footnote to the story of this hugely successful arthropod lineage, which emerged from the oceans to establish themselves as the dominant form of animal life in the early forest environment of the carboniferous period and who continue to be to this day the dominant form of life in terms of numbers of species on this planet. They had one problem with their body plan. They couldn't grow very big because their skeleton was outside their body and not in it. So the land awaited another form of life which could master the ability to grow big – the tetrapods.

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