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72-457: Ptinidae is a family of beetles in the superfamily Bostrichoidea . There are at least 220 genera and 2,200 described species in Ptinidae worldwide. The family includes spider beetles and deathwatch beetles . The Ptinidae family species are hard to identify because they are so small, and they have a compact body structure. They also have similar morphologies within the genera and species of

144-500: A protective exoskeleton . Exoskeletons contain rigid and resistant components that fulfil a set of functional roles in addition to structural support in many animals, including protection, respiration, excretion, sensation, feeding and courtship display , and as an osmotic barrier against desiccation in terrestrial organisms. Exoskeletons have roles in defence from parasites and predators and in providing attachment points for musculature . Arthropod exoskeletons contain chitin ;

216-421: A "surprisingly narrow range" spanning all four estimates from a minimum of 0.9 to a maximum of 2.1 million beetle species. The four estimates made use of host-specificity relationships (1.5 to 1.9 million), ratios with other taxa (0.9 to 1.2 million), plant:beetle ratios (1.2 to 1.3), and extrapolations based on body size by year of description (1.7 to 2.1 million). This immense diversity led

288-448: A beetle is quite uniform, although specific organs and appendages vary greatly in appearance and function between the many families in the order. Like all insects, beetles' bodies are divided into three sections: the head, the thorax, and the abdomen. Because there are so many species, identification is quite difficult, and relies on attributes including the shape of the antennae, the tarsal formulae and shapes of these small segments on

360-481: A beetle's environment. Beetle families may use antennae in different ways. For example, when moving quickly, tiger beetles may not be able to see very well and instead hold their antennae rigidly in front of them in order to avoid obstacles. Certain Cerambycidae use antennae to balance, and blister beetles may use them for grasping. Some aquatic beetle species may use antennae for gathering air and passing it under

432-486: A calcified exoskeleton, but mineralized skeletons did not become common until the beginning of the Cambrian period, with the rise of the " small shelly fauna ". Just after the base of the Cambrian, these miniature fossils become diverse and abundant – this abruptness may be an illusion since the chemical conditions which preserved the small shells appeared at the same time. Most other shell-forming organisms appeared during

504-432: A calcified exoskeleton. Some Cloudina shells even show evidence of predation, in the form of borings. The fossil record primarily contains mineralized exoskeletons, since these are by far the most durable. Since most lineages with exoskeletons are thought to have started with a non-mineralized exoskeleton which they later mineralized, it is difficult to comment on the very early evolution of each lineage's exoskeleton. It

576-406: A common misconception, echinoderms do not possess an exoskeleton and their test is always contained within a layer of living tissue. Exoskeletons have evolved independently many times; 18 lineages evolved calcified exoskeletons alone. Further, other lineages have produced tough outer coatings, such as some mammals, that are analogous to an exoskeleton. This coating is constructed from bone in

648-764: A few fossils from North America before the middle Permian , although both Asia and North America had been united to Euramerica . The first discoveries from North America made in the Wellington Formation of Oklahoma were published in 2005 and 2008. The earliest members of modern beetle lineages appeared during the Late Permian . In the Permian–Triassic extinction event at the end of the Permian, most "protocoleopteran" lineages became extinct. Beetle diversity did not recover to pre-extinction levels until

720-441: A light-emitting organ for mating and communication purposes. Beetles typically have a particularly hard exoskeleton including the elytra , though some such as the rove beetles have very short elytra while blister beetles have softer elytra. The general anatomy of a beetle is quite uniform and typical of insects, although there are several examples of novelty, such as adaptations in water beetles which trap air bubbles under

792-406: A mass of at least 115 g (4.1 oz) and a length of 11.5 cm (4.5 in). Adult male goliath beetles are the heaviest beetle in its adult stage, weighing 70–100 g (2.5–3.5 oz) and measuring up to 11 cm (4.3 in). Adult elephant beetles , Megasoma elephas and Megasoma actaeon often reach 50 g (1.8 oz) and 10 cm (3.9 in). The longest beetle

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864-461: A mobile tooth on their left mandible. The consistency of beetle morphology , in particular their possession of elytra , has long suggested that Coleoptera is monophyletic , though there have been doubts about the arrangement of the suborders , namely the Adephaga , Archostemata , Myxophaga and Polyphaga within that clade . The twisted-wing parasites, Strepsiptera , are thought to be

936-490: A particularly hard exoskeleton and hard forewings ( elytra ) not usable for flying. Almost all beetles have mandibles that move in a horizontal plane. The mouthparts are rarely suctorial, though they are sometimes reduced; the maxillae always bear palps. The antennae usually have 11 or fewer segments, except in some groups like the Cerambycidae (longhorn beetles) and the Rhipiceridae (cicada parasite beetles). The coxae of

1008-708: A sister group to the beetles, having split from them in the Early Permian . Molecular phylogenetic analysis confirms that the Coleoptera are monophyletic. Duane McKenna et al. (2015) used eight nuclear genes for 367 species from 172 of 183 Coleopteran families. They split the Adephaga into 2 clades, Hydradephaga and Geadephaga, broke up the Cucujoidea into 3 clades, and placed the Lymexyloidea within

1080-408: A string of beads , comb-like (either on one side or both, bipectinate), or toothed . The physical variation of antennae is important for the identification of many beetle groups. The Curculionidae have elbowed or geniculate antennae. Feather like flabellate antennae are a restricted form found in the Rhipiceridae and a few other families. The Silphidae have a capitate antennae with a spherical head at

1152-490: Is a species that is often found emerging from in-home wood furnishings. The "drugstore beetle", Stegobium paniceum , is known to infest a variety of stored materials, including bread, flour, cereal, prescription drugs, strychnine powder, packaged foods, and even Egyptian tombs. The "cigarette beetle," Lasioderma serricorne , is a widespread and destructive pest of harvested and manufactured tobacco. Damage and economic losses from L. serricorne infestations were estimated by

1224-489: Is as agricultural, forestry, and horticultural pests . Serious pest species include the boll weevil of cotton, the Colorado potato beetle , the coconut hispine beetle , the mountain pine beetle , and many others. Most beetles, however, do not cause economic damage and some, such as numerous species of lady beetles , are beneficial by helping to control insect pests. The name of the taxonomic order, Coleoptera, comes from

1296-488: Is eventually hardened. In contrast, moulting reptiles shed only the outer layer of skin and often exhibit indeterminate growth. These animals produce new skin and integuments throughout their life, replacing them according to growth. Arthropod growth, however, is limited by the space within its current exoskeleton. Failure to shed the exoskeleton once outgrown can result in the animal's death or prevent subadults from reaching maturity, thus preventing them from reproducing. This

1368-438: Is found, from trees and their bark to flowers, leaves, and underground near roots - even inside plants in galls, in every plant tissue, including dead or decaying ones. Tropical forest canopies have a large and diverse fauna of beetles, including Carabidae , Chrysomelidae , and Scarabaeidae . The heaviest beetle, indeed the heaviest insect stage, is the larva of the goliath beetle , Goliathus goliatus , which can attain

1440-544: Is in creating the proteins and polysaccharides required for the shell's composite structure , not in the precipitation of the mineral components. Skeletonization also appeared at almost the same time that animals started burrowing to avoid predation, and one of the earliest exoskeletons was made of glued-together mineral flakes, suggesting that skeletonization was likewise a response to increased pressure from predators. Ocean chemistry may also control which mineral shells are constructed of. Calcium carbonate has two forms,

1512-602: Is known, however, that in a very short course of time, just before the Cambrian period, exoskeletons made of various materials – silica, calcium phosphate , calcite , aragonite , and even glued-together mineral flakes – sprang up in a range of different environments. Most lineages adopted the form of calcium carbonate which was stable in the ocean at the time they first mineralized, and did not change from this mineral morph - even when it became less favourable. Some Precambrian (Ediacaran) organisms produced tough but non-mineralized outer shells, while others, such as Cloudina , had

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1584-548: Is the Hercules beetle Dynastes hercules , with a maximum overall length of at least 16.7 cm (6.6 in) including the very long pronotal horn. The smallest recorded beetle and the smallest free-living insect (as of 2015 ), is the featherwing beetle Scydosella musawasensis which may measure as little as 325  μm in length. The oldest known beetle is Coleopsis , from the earliest Permian ( Asselian ) of Germany, around 295 million years ago. Early beetles from

1656-404: Is the largest of all orders, constituting almost 40% of described insects and 25% of all known animal species; new species are discovered frequently, with estimates suggesting that there are between 0.9 and 2.1 million total species. However, the number of beetle species is challenged by the number of species in dipterans (flies) and hymenopterans (wasps). Found in almost every habitat except

1728-437: Is the largest suborder, containing more than 300,000 described species in more than 170 families, including rove beetles (Staphylinidae), scarab beetles ( Scarabaeidae ), blister beetles (Meloidae), stag beetles (Lucanidae) and true weevils ( Curculionidae ). These polyphagan beetle groups can be identified by the presence of cervical sclerites (hardened parts of the head used as points of attachment for muscles) absent in

1800-402: Is the mechanism behind some insect pesticides, such as Azadirachtin . Exoskeletons, as hard parts of organisms, are greatly useful in assisting the preservation of organisms, whose soft parts usually rot before they can be fossilized. Mineralized exoskeletons can be preserved as shell fragments. The possession of an exoskeleton permits a couple of other routes to fossilization . For instance,

1872-866: The Dytiscidae (diving beetles) , Haliplidae , and many species of Hydrophilidae , the legs, often the last pair, are modified for swimming, typically with rows of long hairs. Male diving beetles have suctorial cups on their forelegs that they use to grasp females. Other beetles have fossorial legs widened and often spined for digging. Species with such adaptations are found among the scarabs, ground beetles, and clown beetles ( Histeridae ). The hind legs of some beetles, such as flea beetles (within Chrysomelidae) and flea weevils (within Curculionidae), have enlarged femurs that help them leap. Exoskeleton Examples of exoskeletons in animals include

1944-531: The Greek koleopteros (κολεόπτερος), given to the group by Aristotle for their elytra , hardened shield-like forewings, from koleos , sheath, and pteron , wing. The English name beetle comes from the Old English word bitela , little biter, related to bītan (to bite), leading to Middle English betylle . Another Old English name for beetle is ċeafor , chafer, used in names such as cockchafer , from

2016-664: The Middle Triassic . During the Jurassic ( 210 to 145 mya ), there was a dramatic increase in the diversity of beetle families, including the development and growth of carnivorous and herbivorous species. The Chrysomeloidea diversified around the same time, feeding on a wide array of plant hosts from cycads and conifers to angiosperms . Close to the Upper Jurassic, the Cupedidae decreased, but

2088-515: The armadillo , and hair in the pangolin . The armour of reptiles like turtles and dinosaurs like Ankylosaurs is constructed of bone; crocodiles have bony scutes and horny scales. Since exoskeletons are rigid, they present some limits to growth. Organisms with open shells can grow by adding new material to the aperture of their shell, as is the case in gastropods , bivalves , and other molluscans . A true exoskeleton, like that found in panarthropods, must be shed via moulting ( ecdysis ) when

2160-439: The cuticle skeletons shared by arthropods ( insects , chelicerates , myriapods and crustaceans ) and tardigrades , as well as the skeletal cups formed by hardened secretion of stony corals , the test /tunic of sea squirts and sea urchins , and the prominent mollusc shell shared by snails , clams , tusk shells , chitons and nautilus . Some vertebrate animals, such as the turtle , have both an endoskeleton and

2232-431: The sacred scarabs of ancient Egypt to beetlewing art and use as pets or fighting insects for entertainment and gambling. Many beetle groups are brightly and attractively colored making them objects of collection and decorative displays. Over 300 species are used as food , mostly as larvae ; species widely consumed include mealworms and rhinoceros beetle larvae. However, the major impact of beetles on human life

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2304-415: The telephone-pole beetle . The Archostemata have an exposed plate called the metatrochantin in front of the basal segment or coxa of the hind leg. Myxophaga contains about 65 described species in four families, mostly very small, including Hydroscaphidae and the genus Sphaerius . The myxophagan beetles are small and mostly alga-feeders. Their mouthparts are characteristic in lacking galeae and having

2376-515: The Cambrian period, with the Bryozoans being the only calcifying phylum to appear later, in the Ordovician . The sudden appearance of shells has been linked to a change in ocean chemistry which made the calcium compounds of which the shells are constructed stable enough to be precipitated into a shell. However, this is unlikely to be a sufficient cause, as the main construction cost of shells

2448-707: The Cretaceous. The first scarab beetles were not coprophagous but presumably fed on rotting wood with the help of fungus; they are an early example of a mutualistic relationship. There are more than 150 important fossil sites from the Jurassic, the majority in Eastern Europe and North Asia. Outstanding sites include Solnhofen in Upper Bavaria , Germany, Karatau in South Kazakhstan ,

2520-572: The Permian, which are collectively grouped into the " Protocoleoptera " are thought to have been xylophagous (wood eating) and wood boring . Fossils from this time have been found in Siberia and Europe, for instance in the red slate fossil beds of Niedermoschel near Mainz, Germany. Further fossils have been found in Obora, Czech Republic and Tshekarda in the Ural mountains, Russia. However, there are only

2592-483: The Proto-Germanic * kebrô ("beetle"; compare German Käfer , Dutch kever , Afrikaans kewer ). Beetles are by far the largest order of insects: the roughly 400,000 species make up about 40% of all insect species so far described, and about 25% of all animal species. A 2015 study provided four independent estimates of the total number of beetle species, giving a mean estimate of some 1.5 million with

2664-662: The Quaternary caused beetles to change their geographic distributions so much that current location gives little clue to the biogeographical history of a species. It is evident that geographic isolation of populations must often have been broken as insects moved under the influence of changing climate, causing mixing of gene pools, rapid evolution, and extinctions, especially in middle latitudes. The very large number of beetle species poses special problems for classification . Some families contain tens of thousands of species, and need to be divided into subfamilies and tribes. Polyphaga

2736-2009: The Tenebrionoidea. The Polyphaga appear to date from the Triassic. Most extant beetle families appear to have arisen in the Cretaceous. The cladogram is based on McKenna (2015). The number of species in each group (mainly superfamilies) is shown in parentheses, and boldface if over 10,000. English common names are given where possible. Dates of origin of major groups are shown in italics in millions of years ago (mya). Archostemata 160 mya (40) [REDACTED] Myxophaga 220 mya (94) [REDACTED] Hydradephaga (5,560) e.g. Dytiscidae (diving beetles) [REDACTED] Geadephaga ( 35,000 ) e.g. Carabidae (ground beetles) [REDACTED] Scirtoidea (800) + Derodontoidea (29) 200 mya [REDACTED] Staphylinidae 195 mya ( 48,000 , rove beetles) [REDACTED] Scarabaeoidea 145 mya ( 35,000 , scarabs, stag beetles, etc.) [REDACTED] Hydrophiloidea (2,800, water scavenger beetles) [REDACTED] Histeroidea (3,800, clown beetles) [REDACTED] Nosodendridae (70) Dascilloidea (180) [REDACTED] Buprestoidea ( 14,000 , jewel beetles) [REDACTED] Byrrhoidea (400, pill and turtle beetles, etc.) [REDACTED] Elateroidea ( 23,000 , click and soldier beetles, fireflies) [REDACTED] Bostrichoidea (3150, deathwatch, powderpost and skin beetles) [REDACTED] Coccinelloidea (6,000, ladybirds or lady beetles) [REDACTED] Tenebrionoidea 180 mya ( 35,000 , leaf/flower beetles, etc.) and Lymexyloidea [REDACTED] Cleroidea (9,900, checkered beetles and allies) [REDACTED] Cucujoidea (8,000) [REDACTED] Chrysomelidae ( 35,000 , leaf beetles) [REDACTED] Cerambycidae ( 25,000 , longhorn beetles) [REDACTED] Curculionoidea ( 97,000 , weevils) [REDACTED] Beetles are generally characterized by

2808-487: The USDA to be 0.7% of the total warehoused tobacco commodity in 1971. Beetle See subgroups of the order Coleoptera Beetles are insects that form the order Coleoptera ( / k oʊ l iː ˈ ɒ p t ər ə / ), in the superorder Holometabola . Their front pair of wings are hardened into wing-cases, elytra , distinguishing them from most other insects. The Coleoptera, with about 400,000 described species,

2880-763: The Upper Cretaceous include Kzyl-Dzhar in South Kazakhstan and Arkagala in Russia. Beetle fossils are abundant in the Cenozoic; by the Quaternary (up to 1.6 mya), fossil species are identical to living ones, while from the Late Miocene (5.7 mya) the fossils are still so close to modern forms that they are most likely the ancestors of living species. The large oscillations in climate during

2952-797: The Yixian formation in Liaoning , North China, as well as the Jiulongshan formation and further fossil sites in Mongolia . In North America there are only a few sites with fossil records of insects from the Jurassic, namely the shell limestone deposits in the Hartford basin, the Deerfield basin and the Newark basin. The Cretaceous saw the fragmenting of the southern landmass, with the opening of

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3024-465: The addition of calcium carbonate makes them harder and stronger, at the price of increased weight. Ingrowths of the arthropod exoskeleton known as apodemes serve as attachment sites for muscles. These structures are composed of chitin and are approximately six times stronger and twice the stiffness of vertebrate tendons . Similar to tendons, apodemes can stretch to store elastic energy for jumping, notably in locusts . Calcium carbonates constitute

3096-449: The animal starts to outgrow it. A new exoskeleton is produced beneath the old one, and the new skeleton is soft and pliable before shedding the old one. The animal will typically stay in a den or burrow during moulting, as it is quite vulnerable to trauma during this period. Once at least partially set, the organism will plump itself up to try to expand the exoskeleton. The new exoskeleton is still capable of growing to some degree before it

3168-456: The aquatic whirligig beetles ( Gyrinidae ), where they are split to allow a view both above and below the waterline. A few Longhorn beetles ( Cerambycidae ) and weevils as well as some fireflies ( Rhagophthalmidae ) have divided eyes, while many have eyes that are notched, and a few have ocelli , small, simple eyes usually farther back on the head (on the vertex ); these are more common in larvae than in adults. The anatomical organization of

3240-447: The back part of the thorax is concealed by the beetle's wings . This further segmentation is usually best seen on the abdomen. The multisegmented legs end in two to five small segments called tarsi. Like many other insect orders, beetles have claws, usually one pair, on the end of the last tarsal segment of each leg. While most beetles use their legs for walking, legs have been variously adapted for other uses. Aquatic beetles including

3312-631: The bark of trees together with the jewel beetles (Buprestidae). The diversity of jewel beetles increased rapidly, as they were the primary consumers of wood, while longhorn beetles ( Cerambycidae ) were rather rare: their diversity increased only towards the end of the Upper Cretaceous. The first coprophagous beetles are from the Upper Cretaceous and may have lived on the excrement of herbivorous dinosaurs. The first species where both larvae and adults are adapted to an aquatic lifestyle are found. Whirligig beetles (Gyrinidae) were moderately diverse, although other early beetles (e.g. Dytiscidae) were less, with

3384-433: The body whilst submerged. Equally, some families use antennae during mating, and a few species use them for defense. In the cerambycid Onychocerus albitarsis , the antennae have venom injecting structures used in defense, which is unique among arthropods . Antennae vary greatly in form, sometimes between the sexes, but are often similar within any given family. Antennae may be clubbed , threadlike , angled , shaped like

3456-555: The compound eyes may be modified and depends on whether a species is primarily crepuscular, or diurnally or nocturnally active. Ocelli are found in the adult carpet beetle (as a single central ocellus in Dermestidae ), some rove beetles ( Omaliinae ), and the Derodontidae . Beetle antennae are primarily organs of sensory perception and can detect motion, odor and chemical substances, but may also be used to physically feel

3528-651: The diversity of the early plant-eating species increased. Most recent plant-eating beetles feed on flowering plants or angiosperms, whose success contributed to a doubling of plant-eating species during the Middle Jurassic . However, the increase of the number of beetle families during the Cretaceous does not correlate with the increase of the number of angiosperm species. Around the same time, numerous primitive weevils (e.g. Curculionoidea ) and click beetles (e.g. Elateroidea ) appeared. The first jewel beetles (e.g. Buprestidae ) are present, but they remained rare until

3600-715: The elytra for use while diving. Beetles are holometabolans , which means that they undergo complete metamorphosis , with a series of conspicuous and relatively abrupt changes in body structure between hatching and becoming adult after a relatively immobile pupal stage. Some, such as stag beetles , have a marked sexual dimorphism , the males possessing enormously enlarged mandibles which they use to fight other males. Many beetles are aposematic , with bright colors and patterns warning of their toxicity, while others are harmless Batesian mimics of such insects. Many beetles, including those that live in sandy places, have effective camouflage . Beetles are prominent in human culture , from

3672-590: The evolutionary biologist J. B. S. Haldane to quip, when some theologians asked him what could be inferred about the mind of the Christian God from the works of His Creation, "An inordinate fondness for beetles". However, the ranking of beetles as most diverse has been challenged. Multiple studies posit that Diptera (flies) and/or Hymenoptera (sawflies, wasps, ants and bees) may have more species. Beetles are found in nearly all habitats, including freshwater and coastal habitats, wherever vegetative foliage

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3744-410: The family. There are three main groups in the superfamily Bostrichoidea: Bostrichidae , Anobiidae, and Ptinidae. These have undergone frequent changes in hierarchical classification since their inception. They have been treated as a single family, three independent families, the two families Bostrichidae and Anobiidae, or the two families Bostrichidae and Ptinidae. More recent literature treats these as

3816-440: The first part is called the scape and the second part is the pedicel. The other segments are jointly called the flagellum. Beetles have mouthparts like those of grasshoppers . The mandibles appear as large pincers on the front of some beetles. The mandibles are a pair of hard, often tooth-like structures that move horizontally to grasp, crush, or cut food or enemies (see defence , below). Two pairs of finger-like appendages,

3888-468: The fossil record shortly before the base of the Cambrian period , 550  million years ago . The evolution of a mineralised exoskeleton is considered a possible driving force of the Cambrian explosion of animal life, resulting in a diversification of predatory and defensive tactics. However, some Precambrian ( Ediacaran ) organisms produced tough outer shells while others, such as Cloudina , had

3960-431: The legs are usually located recessed within a coxal cavity. The genitalic structures are telescoped into the last abdominal segment in all extant beetles. Beetle larvae can often be confused with those of other holometabolan groups. The beetle's exoskeleton is made up of numerous plates, called sclerites , separated by thin sutures. This design provides armored defenses while maintaining flexibility. The general anatomy of

4032-407: The legs, the mouthparts, and the ventral plates (sterna, pleura, coxae). In many species accurate identification can only be made by examination of the unique male genitalic structures. The head, having mouthparts projecting forward or sometimes downturned, is usually heavily sclerotized and is sometimes very large. The eyes are compound and may display remarkable adaptability, as in the case of

4104-421: The magnesium/calcium ratio of the oceans appears to have a negligible impact on organisms' success, which is instead controlled mainly by how well they recover from mass extinctions. A recently discovered modern gastropod Chrysomallon squamiferum that lives near deep-sea hydrothermal vents illustrates the influence of both ancient and modern local chemical environments: its shell is made of aragonite, which

4176-489: The maxillary and labial palpi, are found around the mouth in most beetles, serving to move food into the mouth. In many species, the mandibles are sexually dimorphic, with those of the males enlarged enormously compared with those of females of the same species. The thorax is segmented into the two discernible parts, the pro- and pterothorax. The pterothorax is the fused meso- and metathorax, which are commonly separated in other insect species, although flexibly articulate from

4248-426: The molluscs, whose shells often comprise both forms, most lineages use just one form of the mineral. The form used appears to reflect the seawater chemistry – thus which form was more easily precipitated – at the time that the lineage first evolved a calcified skeleton, and does not change thereafter. However, the relative abundance of calcite- and aragonite-using lineages does not reflect subsequent seawater chemistry –

4320-489: The most widespread being the species of Coptoclavidae , which preyed on aquatic fly larvae. A 2020 review of the palaeoecological interpretations of fossil beetles from Cretaceous ambers has suggested that saproxylicity was the most common feeding strategy, with fungivorous species in particular appearing to dominate. Many fossil sites worldwide contain beetles from the Cretaceous. Most are in Europe and Asia and belong to

4392-490: The other suborders. Adephaga contains about 10 families of largely predatory beetles, includes ground beetles (Carabidae), water beetles ( Dytiscidae ) and whirligig beetles (Gyrinidae). In these insects, the testes are tubular and the first abdominal sternum (a plate of the exoskeleton ) is divided by the hind coxae (the basal joints of the beetle's legs). Archostemata contains four families of mainly wood-eating beetles, including reticulated beetles (Cupedidae) and

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4464-614: The parts of organisms that were already mineralised are usually preserved, such as the shells of molluscs. It helps that exoskeletons often contain "muscle scars", marks where muscles have been attached to the exoskeleton, which may allow the reconstruction of much of an organism's internal parts from its exoskeleton alone. The most significant limitation is that, although there are 30-plus phyla of living animals, two-thirds of these phyla have never been found as fossils, because most animal species are soft-bodied and decay before they can become fossilised. Mineralized skeletons first appear in

4536-410: The prothorax. When viewed from below, the thorax is that part from which all three pairs of legs and both pairs of wings arise. The abdomen is everything posterior to the thorax. When viewed from above, most beetles appear to have three clear sections, but this is deceptive: on the beetle's upper surface, the middle section is a hard plate called the pronotum , which is only the front part of the thorax;

4608-510: The sea and the polar regions , they interact with their ecosystems in several ways: beetles often feed on plants and fungi , break down animal and plant debris, and eat other invertebrates . Some species are serious agricultural pests, such as the Colorado potato beetle , while others such as Coccinellidae (ladybirds or ladybugs) eat aphids , scale insects , thrips , and other plant-sucking insects that damage crops. Some others also have unusual characteristics, such as fireflies , which use

4680-404: The shells of molluscs, brachiopods , and some tube-building polychaete worms. Silica forms the exoskeleton in the microscopic diatoms and radiolaria . One mollusc species, the scaly-foot gastropod , even uses the iron sulfides greigite and pyrite . Some organisms, such as some foraminifera , agglutinate exoskeletons by sticking grains of sand and shell to their exterior. Contrary to

4752-664: The southern Atlantic Ocean and the isolation of New Zealand, while South America, Antarctica, and Australia grew more distant. The diversity of Cupedidae and Archostemata decreased considerably. Predatory ground beetles (Carabidae) and rove beetles (Staphylinidae) began to distribute into different patterns; the Carabidae predominantly occurred in the warm regions, while the Staphylinidae and click beetles (Elateridae) preferred temperate climates. Likewise, predatory species of Cleroidea and Cucujoidea hunted their prey under

4824-437: The stable calcite and the metastable aragonite, which is stable within a reasonable range of chemical environments but rapidly becomes unstable outside this range. When the oceans contain a relatively high proportion of magnesium compared to calcium, aragonite is more stable, but as the magnesium concentration drops, it becomes less stable, hence harder to incorporate into an exoskeleton, as it will tend to dissolve. Except for

4896-511: The strong layer can resist compaction, allowing a mould of the organism to be formed underneath the skeleton, which may later decay. Alternatively, exceptional preservation may result in chitin being mineralised, as in the Burgess Shale , or transformed to the resistant polymer keratin , which can resist decay and be recovered. However, our dependence on fossilised skeletons also significantly limits our understanding of evolution. Only

4968-702: The temperate climate zone during the Cretaceous. Lower Cretaceous sites include the Crato fossil beds in the Araripe basin in the Ceará , North Brazil, as well as overlying Santana formation; the latter was near the equator at that time. In Spain, important sites are near Montsec and Las Hoyas . In Australia, the Koonwarra fossil beds of the Korumburra group, South Gippsland , Victoria, are noteworthy. Major sites from

5040-485: The tip. The Scarabaeidae typically have lamellate antennae with the terminal segments extended into long flat structures stacked together. The Carabidae typically have thread-like antennae. The antennae arises between the eye and the mandibles and in the Tenebrionidae, the antennae rise in front of a notch that breaks the usually circular outline of the compound eye. They are segmented and usually consist of 11 parts,

5112-426: The two families Bostrichidae and Ptinidae, with Anobiidae a subfamily of Ptinidae ( Anobiinae ). Spider beetles are so named because they look like spiders. Some species have long legs, antennae that can seem like an additional pair of legs, and a body shape that may appear superficially like that of a spider. Deathwatch beetles are named because of a clicking noise that two (and possibly more) species tend to make in

5184-681: The walls of houses and other buildings. This clicking noise is designed to communicate with potential mates, but has historically caused fear of impending death during times of plague and sickness. The larvae of a number of Ptinidae species tend to bore into wood, earning them the name "woodworm" or "wood borer". Several species are pests, causing damage to wooden furniture, house structures, tobacco, and dried food products. The deathwatch beetles Xestobium rufovillosum , Hemicoelus carinatus , and Hemicoelus gibbicollis are economically significant pests, damaging flooring, joists, and other timber in housing. The "furniture beetle", Anobium punctatum ,

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