Coxoplectoptera
Encyclopedia
Coxoplectoptera or "chimera wings" is a primitive, extinct order
of winged insects
containing one family, Mickoleitiidae, described by Staniczek, Bechly & Godunko in 2011. Two adult and more than 20 larval fossils have been scientifically described from Mesozoic outcrops, mainly from the Lower Cretaceous Crato Formation
of Brazil
(totally at least 30-40 fossil larvae have been found). Coxoplectoptera belong to the stem group of mayflies
. Winged adults and the aquatic larvae were predators with raptorial forelegs, which are reminiscent to those of praying mantids. The larvae had a peculiar freshwater shrimp
-like habitus.
's "Phylogenetic Systematics
". The scientific name of the order Coxoplectoptera refers to the prolonged coxal segment of the larval and adult legs, and the old scientific name Plectoptera for mayflies (not to be confused with Plecoptera
for stoneflies). The common name "chimera wings" was coined in reference to the strange combination of characters in the morphology of the adult animal, which looks like a kind of chimera
built from unrelated insects, with their oblique thorax and broad hind wing shape like a dragonfly, their wing venation like a primitive mayfly ancestor, and their raptorial forelegs like a mantis.
). These larvae were scientifically discovered and first mentioned by Bechly (2001: fig. 36), who also pointed to their strange morphology. Staniczek (2002, 2003) discussed the larvae as well and claimed that they arguably had been a kind of living fossil
in the Lower Cretaceous. The German biologist Rainer Willmann described the larvae in a chapter in Martill, Bechly & Loveridge (2007) and erroneously attributed them to the extinct stem group mayfly family Cretereismatidae that he described based on adult specimens from the same locality. During the work for this monograph on the Crato Formation the German palaeoentomologist Günter Bechly and entomologist Arnold H. Staniczek discovered in the fossil collection of the Stuttgart State Museum of Natural History
the very adult specimen that later would become the holotype
of Mickoleitia longimanus. They figured this fossil in Martill, Bechly & Loveridge 2007 (Fig. 11.90i,j) as undescribed stem group mayfly and indicated in a brief figure legend the possible relationship to the erratic larvae. The detailed scientific description of Coxoplectoptera and the demonstration of the relationship of fossil adult and larvae was finally published by Staniczek, Bechly & Godunko (2011) in a special issue on Cretaceous insects of the journal "Insect Systematics & Evolution". The authors also determined that two fossil larvae (Mesogenesia petersae = Archaeobehnigia edmundsi) that had been erroneously described by Tshernova (1977) as modern mayfly larvae from the Middle
or Upper Jurassic of Transbaikal
s, can be attributed the order Coxoplectoptera. The discovery of Coxoplectoptera represented one of the more spectacular findings of paleontology in 2011
and was heavily covered by news media around the globe.
is not preserved in the single known fossil holotype specimen). A second unnamed species of the genus Mickoleitia was only of half this size, and is only known by a single adult specimen from a private fossil collection in Japan
. The head of Mickoleitia was provided with large compound eyes and functional mouthparts
(preserved are 3-segmented labial palps). The thoracic
segments are obliquely tilted backwards as in dragonflies, so that the raptorial forelegs are shifted forwards. All legs have a strongly prolonged and free coxal segment. The forelegs are developed as subchelate raptorial devices with a single-segmented tarsus with an unpaired claw. Most likely the abdomen was provided with three caudal filaments (two lateral cerci
and the median epiproct) as in modern mayflies and their Permian
stem group representatives (Permoplectoptera, e.g. Protereismatidae). Since males of modern mayflies and of Permoplectoptera have gonopods on the 9th abdominal segment that are developed as genital claspers to grip the female for copulation, such a character state and behavior is also likely for Coxoplectoptera, who have an intermediate position as phylogenetic
link between these two groups.
larvae, and rather resembles the body of gammarid
freshwater shrimps. Many of the fossil larvae are preserved in a characteristic posture with arched back, erect antennae and terminal filaments, and forelegs always in catching position similar to a praying mantis. The head was strongly armored and provided with horn- or shovel-like projections. Of the mouthparts only the crossed, sabre-like mandibles and the spoon-shaped labium are known. All legs have a strongly prolonged and free coxal segment as in the adult. Likewise, the forelegs are developed as slender subchelate raptorial legs with nearly identical segment proportions as in the adult stage, but with a shorter tibia that may have been fused with the single-segmented tarsus, which ended in an unpaired claw. Styliform and ventrally directed abdominal gills are developed on abdominal segments 1-7. These gills are composed of a broader, more strongly sclerotized basal part and a slender and rather membranous distal part. The gills articulate dorsally within the abdominal tergites
that are distinctly separated from the ventral sternites. The caudal filaments are formed by the two lateral cerci and the slightly longer medial terminal filament. All three appendages are lined with dense rows of long and thin setae.
s (7 pairs of abdominal gills, 3 caudal filaments with dense rows of swimming hairs) prove that the larvae have been living in freshwater of streams and rivers, just like those of modern mayflies. They were washed in as allochthonous
elements into the brackish Crato lagoon, were the limestones were deposited. The raptorial forelegs, sabre-like mandibles, large eyes and long antennae indicate that the larvae were predators like the adults. On the other hand, the strong, shortened and broadened mid- and hind legs, the strong body armature, and shovel-like projections on the head all suggest that the animals were burrowing. Staniczek, Bechly & Godunko (2011) therefore assumed that the larvae were ambush predator
s that were hiding, partly burrowed in the river bed
, and waiting for small prey passing by.
record, comparative morphology, developmental biology
and genetics
. The expression of leg gene
s in the ontogeny
of the insect wing has been universally considered as conclusive evidence in favour of the leg-exite-hypothesis, which proposes that insect wings are derived from mobile leg appendages (exites). However, the larvae of Coxoplectoptera show that the abdominal gills of mayflies and their ancestors, which are generally considered as corresponding structures to insect wings, articulated within the dorsal tergite plates. This cannot be seen in modern mayfly larvae, because their abdominal tergites and sternites are fused, without any traces of separation left even in embryonic development. If larval gills and wings are corresponding ("serial homologous") structures and thus share the same evolutionary origin, the new results from Coxoplectoptera demonstrate that also wings are of tergal origin, as proposed by the classical paranotal-hypothesis. Staniczek, Bechly & Godunko (2011) therefore suggested a new hypothesis that could reconcile the apparently conflicting evidence from paleontology
and developmental genetics: wings first originated as stiff outgrowths of tergal plates (paranota), and only later in evolution became mobile, articulated appendages through secondary recruiting of leg genes.
Within pterygote
insects the Coxoplectoptera represent the sister group of modern mayflies (Ephemeroptera). This relationship is indicated by several synapomorphies
, such as: adult wing venation with costal brace (absent in other winged insects), larvae with 7 pairs of abdominal gills (compared to still 9 pairs in Permoplectoptera like Protereisma larvae), and with single-segmented tarsus with unpaired claw (compared to 3-segmented tarsus with paired claw in Permoplectoptera like Protereisma larvae).
Together with mayflies and dragonflies they belong to the clade Palaeoptera, which is characterized by a derived wing articulation with fused sclerites, a vertical resting position of the wings in the groundplan
, and a wing venation with intercalary veins between the main longitudinal veins (esp. IR1+ between RP1- and RP2-, and IR2+ between RP2- and RP3/4-).
Because of some very primitive character states, the Coxoplectoptera rather looked like early Paleozoic
ancestors of mayflies, e.g. in the wing venation of the adult stage they still had the elongate costal brace that is not fused to the costal margin, and in the larval stage they still had articulated lateral wing pads. The large and broad hind wings are a further plesiomorphy compared to the small hind wing of modern mayflies, and even compared to the slender hind wing of Permian
stem group mayflies like Protereisma.
The monophyly of Coxoplectoptera is demonstrated by several autapomorphic
characters in the adult stage, such as the raptorial forelegs and single-segmented tarsi with unpaired claw, as well as in the larval stage by the laterally compressed body, the body armature, the raptorial forelegs and burrowing mid- and hind legs, and the styliform shape of the ventrally directed abdominal gills.
Coxoplectoptera are only known from the Jurassic and the Lower Cretaceous. It is not yet known why and when they went extinct
.
Coxoplectoptera only includes a single family
Mickoleitiidae with two Mesozoic
genera
:
Mickoleitia (Lower Cretaceous, Crato Formation
, Brazil
):
Mesogenesia (Middle or Upper Jurassic, Transbaikal
s):
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
of winged insects
Pterygota
Pterygota is a subclass of insects that includes the winged insects. It also includes insect orders that are secondarily wingless ....
containing one family, Mickoleitiidae, described by Staniczek, Bechly & Godunko in 2011. Two adult and more than 20 larval fossils have been scientifically described from Mesozoic outcrops, mainly from the Lower Cretaceous Crato Formation
Crato Formation
The Crato Formation is a geologic formation of Early Cretaceous age in northeastern Brazil's Araripe Basin. It is an important Lagerstätte for palaeontologists. The strata were laid down mostly during the early Albian age, about 108 million years ago, in a shallow inland sea...
of Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
(totally at least 30-40 fossil larvae have been found). Coxoplectoptera belong to the stem group of mayflies
Mayfly
Mayflies are insects which belong to the Order Ephemeroptera . They have been placed into an ancient group of insects termed the Palaeoptera, which also contains dragonflies and damselflies...
. Winged adults and the aquatic larvae were predators with raptorial forelegs, which are reminiscent to those of praying mantids. The larvae had a peculiar freshwater shrimp
Gammarus
Gammarus is an amphipod crustacean genus in the family Gammaridae. It contains more than 200 described species, making it one of the most speciose genera of crustaceans...
-like habitus.
Etymology
The genus Mickoleitia and family Mickoleitiidae was named in honor of German zoologist Gerhard Mickoleit from the University of Tübingen, who was among the first proponents of Willi HennigWilli Hennig
Emil Hans Willi Hennig was a German biologist who is considered the founder of phylogenetic systematics, also known as cladistics. With his works on evolution and systematics he revolutionised the view of the natural order of beings...
's "Phylogenetic Systematics
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
". The scientific name of the order Coxoplectoptera refers to the prolonged coxal segment of the larval and adult legs, and the old scientific name Plectoptera for mayflies (not to be confused with Plecoptera
Plecoptera
Plecoptera are an order of insects, commonly known as stoneflies. There are some 3,500 described species worldwide, with new species still being discovered. Stoneflies are found worldwide, except Antarctica...
for stoneflies). The common name "chimera wings" was coined in reference to the strange combination of characters in the morphology of the adult animal, which looks like a kind of chimera
Chimera (mythology)
The Chimera or Chimaera was, according to Greek mythology, a monstrous fire-breathing female creature of Lycia in Asia Minor, composed of the parts of multiple animals: upon the body of a lioness with a tail that ended in a snake's head, the head of a goat arose on her back at the center of her...
built from unrelated insects, with their oblique thorax and broad hind wing shape like a dragonfly, their wing venation like a primitive mayfly ancestor, and their raptorial forelegs like a mantis.
History of discovery
The fossil larvae of the genus Mickoleitia are not extraordinarily rare in the limestones of the Crato Formation, so that the local brick workers even have a common Brazilian name for them ("Abacaxi" = pineapplePineapple
Pineapple is the common name for a tropical plant and its edible fruit, which is actually a multiple fruit consisting of coalesced berries. It was given the name pineapple due to its resemblance to a pine cone. The pineapple is by far the most economically important plant in the Bromeliaceae...
). These larvae were scientifically discovered and first mentioned by Bechly (2001: fig. 36), who also pointed to their strange morphology. Staniczek (2002, 2003) discussed the larvae as well and claimed that they arguably had been a kind of living fossil
Living fossil
Living fossil is an informal term for any living species which appears similar to a species otherwise only known from fossils and which has no close living relatives, or a group of organisms which have long fossil records...
in the Lower Cretaceous. The German biologist Rainer Willmann described the larvae in a chapter in Martill, Bechly & Loveridge (2007) and erroneously attributed them to the extinct stem group mayfly family Cretereismatidae that he described based on adult specimens from the same locality. During the work for this monograph on the Crato Formation the German palaeoentomologist Günter Bechly and entomologist Arnold H. Staniczek discovered in the fossil collection of the Stuttgart State Museum of Natural History
State Museum of Natural History Stuttgart
The State Museum of Natural History Stuttgart is one of the two state of Baden-Württemberg's natural history museums...
the very adult specimen that later would become the holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
of Mickoleitia longimanus. They figured this fossil in Martill, Bechly & Loveridge 2007 (Fig. 11.90i,j) as undescribed stem group mayfly and indicated in a brief figure legend the possible relationship to the erratic larvae. The detailed scientific description of Coxoplectoptera and the demonstration of the relationship of fossil adult and larvae was finally published by Staniczek, Bechly & Godunko (2011) in a special issue on Cretaceous insects of the journal "Insect Systematics & Evolution". The authors also determined that two fossil larvae (Mesogenesia petersae = Archaeobehnigia edmundsi) that had been erroneously described by Tshernova (1977) as modern mayfly larvae from the Middle
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from 176-161 million years ago. In European lithostratigraphy, rocks of this Middle Jurassic age are called the Dogger....
or Upper Jurassic of Transbaikal
Transbaikal
Transbaikal, Trans-Baikal, Transbaikalia , or Dauria is a mountainous region to the east of or "beyond" Lake Baikal in Russia. The alternative name, Dauria, is derived from the ethnonym of the Daur people. It stretches for almost 1000 km from north to south from the Patomskoye Plateau and North...
s, can be attributed the order Coxoplectoptera. The discovery of Coxoplectoptera represented one of the more spectacular findings of paleontology in 2011
2011 in paleontology
-Lobopods:-Arachnids:-Insects:-Newly named jawless vertebrates:-Newly named acanthodian:-Newly named cartilaginous fishes:-Newly named bony fishes:-Newly named lepospondyls:-Newly named temnospondyls:-Newly named lissamphibians:...
and was heavily covered by news media around the globe.
Adult
The adult stage of the type species Mickoleitia longimanus had a wing length of 28-29 mm and a probable body length of ca. 35-40 mm (the abdomenAbdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
is not preserved in the single known fossil holotype specimen). A second unnamed species of the genus Mickoleitia was only of half this size, and is only known by a single adult specimen from a private fossil collection in Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. The head of Mickoleitia was provided with large compound eyes and functional mouthparts
Insect mouthparts
Insects exhibit a range of mouthparts, adapted to particular modes of feeding. The earliest insects had chewing mouthparts...
(preserved are 3-segmented labial palps). The thoracic
Thorax (insect anatomy)
The thorax is the mid section of the insect body. It holds the head, legs, wings and abdomen. It is also called mesosoma in other arthropods....
segments are obliquely tilted backwards as in dragonflies, so that the raptorial forelegs are shifted forwards. All legs have a strongly prolonged and free coxal segment. The forelegs are developed as subchelate raptorial devices with a single-segmented tarsus with an unpaired claw. Most likely the abdomen was provided with three caudal filaments (two lateral cerci
Cercus
Cerci are paired appendages on the rear-most segments of many arthropods, including insects and arachnids but not crustaceans. Cerci often serve as sensory organs, but they may also be used as weapons or copulation aids, or they may simply be vestigial structures.Typical cerci may appear to be...
and the median epiproct) as in modern mayflies and their Permian
Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...
stem group representatives (Permoplectoptera, e.g. Protereismatidae). Since males of modern mayflies and of Permoplectoptera have gonopods on the 9th abdominal segment that are developed as genital claspers to grip the female for copulation, such a character state and behavior is also likely for Coxoplectoptera, who have an intermediate position as phylogenetic
Phylogenetics
In biology, phylogenetics is the study of evolutionary relatedness among groups of organisms , which is discovered through molecular sequencing data and morphological data matrices...
link between these two groups.
Larva
The more than 20 described larvae of different stages have a body length of 10-32 mm. Their laterally compressed body is unique among all known fossil and Recent aquatic insectAquatic insects
Aquatic insects live some portion of their life cycle in the water. They feed in the same ways as other insects. Some diving insects, such as predatory diving beetles, can hunt for food underwater where land-living insects cannot compete.-Breathing:...
larvae, and rather resembles the body of gammarid
Gammarus
Gammarus is an amphipod crustacean genus in the family Gammaridae. It contains more than 200 described species, making it one of the most speciose genera of crustaceans...
freshwater shrimps. Many of the fossil larvae are preserved in a characteristic posture with arched back, erect antennae and terminal filaments, and forelegs always in catching position similar to a praying mantis. The head was strongly armored and provided with horn- or shovel-like projections. Of the mouthparts only the crossed, sabre-like mandibles and the spoon-shaped labium are known. All legs have a strongly prolonged and free coxal segment as in the adult. Likewise, the forelegs are developed as slender subchelate raptorial legs with nearly identical segment proportions as in the adult stage, but with a shorter tibia that may have been fused with the single-segmented tarsus, which ended in an unpaired claw. Styliform and ventrally directed abdominal gills are developed on abdominal segments 1-7. These gills are composed of a broader, more strongly sclerotized basal part and a slender and rather membranous distal part. The gills articulate dorsally within the abdominal tergites
Tergum
A tergum is the dorsal portion of an arthropod segment other than the head. The anterior edge is called the base and posterior edge is called the apex or margin. A given tergum may be divided into hardened plates or sclerites commonly referred to as tergites...
that are distinctly separated from the ventral sternites. The caudal filaments are formed by the two lateral cerci and the slightly longer medial terminal filament. All three appendages are lined with dense rows of long and thin setae.
Adult
Because in the adult holotype specimen well-preserved mouthparts (palps) are visible, the adult animals almost certainly have been feeding. On the contrary the adult insect in modern mayflies is just a non-feeding reproductive stage with strongly reduced mouthparts. The raptorial forelegs and oblique thorax indicate that Mickoleitia was a predator. The large and broad hinds suggest that they were swift fliers like dragonflies and most probably were actively hunting other flying insects.Larva
The abundance of fossils, the circumstances of preservation and special anatomical adaptationAdaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
s (7 pairs of abdominal gills, 3 caudal filaments with dense rows of swimming hairs) prove that the larvae have been living in freshwater of streams and rivers, just like those of modern mayflies. They were washed in as allochthonous
Allochthon
thumb|right|250px|Schematic overview of a thrust system. The hanging wall block is called a [[nappe]]. If an [[erosion]]al hole is created in the nappe that is called a [[window |window]]...
elements into the brackish Crato lagoon, were the limestones were deposited. The raptorial forelegs, sabre-like mandibles, large eyes and long antennae indicate that the larvae were predators like the adults. On the other hand, the strong, shortened and broadened mid- and hind legs, the strong body armature, and shovel-like projections on the head all suggest that the animals were burrowing. Staniczek, Bechly & Godunko (2011) therefore assumed that the larvae were ambush predator
Ambush predator
Ambush predators or sit-and-wait predators are carnivorous animals that capture prey by stealth or cunning, not by speed or necessarily by strength. These organisms usually hide motionless and wait for prey to come within striking distance. They are often camouflaged, and may be solitary...
s that were hiding, partly burrowed in the river bed
Stream bed
A stream bed is the channel bottom of a stream, river or creek; the physical confine of the normal water flow. The lateral confines or channel margins, during all but flood stage, are known as the stream banks or river banks. In fact, a flood occurs when a stream overflows its banks and flows onto...
, and waiting for small prey passing by.
Evolution and phylogeny
The larvae of Coxoplectoptera provided new clues to the disputed question of the evolutionary origin of insect wings. Before this discovery the paranotal-hypothesis and the leg-exite-hypothesis have been considered as incompatible alternative explanations, which have both been supported by a set of evidences from the fossilFossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
record, comparative morphology, developmental biology
Developmental biology
Developmental biology is the study of the process by which organisms grow and develop. Modern developmental biology studies the genetic control of cell growth, differentiation and "morphogenesis", which is the process that gives rise to tissues, organs and anatomy.- Related fields of study...
and genetics
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
. The expression of leg gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
s in the ontogeny
Ontogeny
Ontogeny is the origin and the development of an organism – for example: from the fertilized egg to mature form. It covers in essence, the study of an organism's lifespan...
of the insect wing has been universally considered as conclusive evidence in favour of the leg-exite-hypothesis, which proposes that insect wings are derived from mobile leg appendages (exites). However, the larvae of Coxoplectoptera show that the abdominal gills of mayflies and their ancestors, which are generally considered as corresponding structures to insect wings, articulated within the dorsal tergite plates. This cannot be seen in modern mayfly larvae, because their abdominal tergites and sternites are fused, without any traces of separation left even in embryonic development. If larval gills and wings are corresponding ("serial homologous") structures and thus share the same evolutionary origin, the new results from Coxoplectoptera demonstrate that also wings are of tergal origin, as proposed by the classical paranotal-hypothesis. Staniczek, Bechly & Godunko (2011) therefore suggested a new hypothesis that could reconcile the apparently conflicting evidence from paleontology
Paleontology
Paleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments...
and developmental genetics: wings first originated as stiff outgrowths of tergal plates (paranota), and only later in evolution became mobile, articulated appendages through secondary recruiting of leg genes.
Within pterygote
Pterygota
Pterygota is a subclass of insects that includes the winged insects. It also includes insect orders that are secondarily wingless ....
insects the Coxoplectoptera represent the sister group of modern mayflies (Ephemeroptera). This relationship is indicated by several synapomorphies
Synapomorphy
In cladistics, a synapomorphy or synapomorphic character is a trait that is shared by two or more taxa and their most recent common ancestor, whose ancestor in turn does not possess the trait. A synapomorphy is thus an apomorphy visible in multiple taxa, where the trait in question originates in...
, such as: adult wing venation with costal brace (absent in other winged insects), larvae with 7 pairs of abdominal gills (compared to still 9 pairs in Permoplectoptera like Protereisma larvae), and with single-segmented tarsus with unpaired claw (compared to 3-segmented tarsus with paired claw in Permoplectoptera like Protereisma larvae).
Together with mayflies and dragonflies they belong to the clade Palaeoptera, which is characterized by a derived wing articulation with fused sclerites, a vertical resting position of the wings in the groundplan
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
, and a wing venation with intercalary veins between the main longitudinal veins (esp. IR1+ between RP1- and RP2-, and IR2+ between RP2- and RP3/4-).
Because of some very primitive character states, the Coxoplectoptera rather looked like early Paleozoic
Paleozoic
The Paleozoic era is the earliest of three geologic eras of the Phanerozoic eon, spanning from roughly...
ancestors of mayflies, e.g. in the wing venation of the adult stage they still had the elongate costal brace that is not fused to the costal margin, and in the larval stage they still had articulated lateral wing pads. The large and broad hind wings are a further plesiomorphy compared to the small hind wing of modern mayflies, and even compared to the slender hind wing of Permian
Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...
stem group mayflies like Protereisma.
The monophyly of Coxoplectoptera is demonstrated by several autapomorphic
Autapomorphy
In cladistics, an autapomorphy is a distinctive anatomical feature, known as a derived trait, that is unique to a given terminal group. That is, it is found only in one member of a clade, but not found in any others or outgroup taxa, not even those most closely related to the group...
characters in the adult stage, such as the raptorial forelegs and single-segmented tarsi with unpaired claw, as well as in the larval stage by the laterally compressed body, the body armature, the raptorial forelegs and burrowing mid- and hind legs, and the styliform shape of the ventrally directed abdominal gills.
Coxoplectoptera are only known from the Jurassic and the Lower Cretaceous. It is not yet known why and when they went extinct
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
.
Systematics
The orderOrder (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Coxoplectoptera only includes a single family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Mickoleitiidae with two Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
:
Mickoleitia (Lower Cretaceous, Crato Formation
Crato Formation
The Crato Formation is a geologic formation of Early Cretaceous age in northeastern Brazil's Araripe Basin. It is an important Lagerstätte for palaeontologists. The strata were laid down mostly during the early Albian age, about 108 million years ago, in a shallow inland sea...
, Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
):
- Mickoleitia longimanus (type speciesType speciesIn biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
) - Mickoleitia spec. (smaller unnamed species, represented by a single adult specimen in a private fossil collection in Japan)
Mesogenesia (Middle or Upper Jurassic, Transbaikal
Transbaikal
Transbaikal, Trans-Baikal, Transbaikalia , or Dauria is a mountainous region to the east of or "beyond" Lake Baikal in Russia. The alternative name, Dauria, is derived from the ethnonym of the Daur people. It stretches for almost 1000 km from north to south from the Patomskoye Plateau and North...
s):
- Mesogenesia petersae (= Archaeobehnigia edmundsi)
External links
- ScienceDaily: Mysterious Fossils Provide New Clues to Insect Evolution
- LiveScience: Ancient 'Frankenstein' Insect Discovered
- Scientific American: Odd Insect Fossils Suggest Early Carnivorous Lifestyle
- Daily Mail: Mysterious 'Frankenstein-like' fossils provide fresh clues to evolution of insects
- MSNBC: Fossil reveals an ancient 'Frankenstein' insect
- Fox News: Ancient 'Frankenstein' Insect Discovered
- YouTube: feature in German L-TV news magazine, incl. interviews
- YouTube: feature in German Regio-TV news journal, incl. interviews