Search

Nymphidae, the group of split-footed lacewings, is a rather species-poor group. Split-footed lacewings nowadays are restricted to Australasia, while fossil forms are also known from other areas of the world, indicating that the group was more species-rich and therefore likely diverse in the past. Split-footed lacewings have rather distinct larvae, roughly resembling antlion larvae, but differing from the latter especially with regard to the mandibles. Antlion larvae usually have three prominent teeth on each mandible, while at least extant larvae of split-footed lacewings only have a single prominent tooth per mandible. Fossils interpreted as larvae of split-footed lacewings are well known from amber from Myanmar (ca. 100 myr; Burmese amber) and by a single specimen from Baltic amber (about 40 myr). We here report additional fossil specimens from Myanmar amber, expanding the known record of fossil forms from six depicted specimens to 15. For the extant fauna, we could compile 25 larvae. We compare the diversity of shape of extant and fossil larvae through time using an outline analysis (based on elliptic Fourier transformation) of the head. The results of this analysis indicate that the morphological diversity, or disparity, of split-footed lacewing larvae was higher in the past than it is today. With this type of analysis, we can show a loss of diversity over time, without the necessity to identify the fossil larvae down to a narrow taxonomical range. A similar pattern has already been recognised in silky lacewings, Psychopsidae. This might indicate a general loss of diversity of lacewing larvae.

The lepidopteran caterpillar is a ubiquitous type of larva with a significant impact on the modern ecosystem. Quite on the contrary, the fossil record of caterpillars is quite scarce, with four occurrences in Cretaceous ambers representing the oldest ones. Here we report a new specimen from 100 million-year-old Cretaceous Myanmar amber. The caterpillar has appendages on abdomen segments 3–6 and 10. Such an arrangement is today only known in caterpillars of the group Gracillariidae. These caterpillars are usually dorso-ventrally flattened, adapted for leaf mining. The fossil specimen does not appear flattened and is additionally armoured with spines dorsally on the trunk segments. All other known Cretaceous larvae are “naked”, lacking dorsal armature. The new specimen hence increases the diversity of Cretaceous caterpillars. This finding is congruent with recent phylogenetic reconstructions and hence supports an early diversification of the group Lepidoptera.

The Solnhofen Konservat-Lagerstätte yields a great number of remarkably preserved fossils of eumalacostracan crustaceans that help us understand the early radiation of several groups with modern representatives. One fossil from there, Francocaris grimmi Broili, 1917 is a small shrimp-like crustacean originally described about 100 years ago as a mysidacean crustacean (opossum shrimps and relatives) from latest Kimmeridgian – early Tithonian (Upper Jurassic) of the Solnhofen Lithographic Limestones of Southern Germany. New material with exceptionally preserved specimens, allied with modern imaging techniques (mostly composite fluorescence microscopy), allows us to provide a detailed re-description of this species. The most striking feature of Francocaris grimmi is an extremely elongated thoracopod 7 with its distal elements forming a spiny sub-chela. This character supports a sister group relationship of Francocaris grimmi with Eucopiidae, an ingroup of Lophogastrida, pelagic peracaridans common in marine environments throughout the world. We also discuss other supposed fossil representatives of Lophogastrida, identifying all of them as problematic at best. The structure of the sub-chela in F. grimmi indicates an original use in raptorial behaviour. Francocaris grimmi appears to be unique in possessing such a far posterior sub-chelate appendage as a major raptorial structure. In most representatives of Euarthropoda in which sub-chelate appendages occur and are used for food intake, they are usually closer to the mouth.

Larvae of lacewings (Neuroptera) are known to be fierce predators. According to the morphology of fossil forms thisseems to have been the case already in the Early Cretaceous. While being predators, lacewing larvae are also food itemsfor other organisms. Here we report two pieces of amber from Myanmar providing instances of such cases. In one amberpiece several isolated stylets of lacewing larvae are preserved closely associated together. The most likely interpretationis that a predator preying on lacewing larvae has regurgitated or defecated these non-digestible pieces, yet the identityof the predator remains unclear. The other amber piece preserves a larva resembling modern day larvae of split-footedlacewings (Nymphidae). The larva has projections on its trunk, allowing it to wear a camouflaging cloak. In the headregion, a mite (Acari) is attached to the larva; more precisely, the entire anterior body region of the mite is apparentlyinserted into the lacewing larva. The mite is smaller than the larva. It is known from the modern fauna that stage 1 larvaeof Ascalaphidae can be attacked also by rather small predators, such as ants. The mite can therefore well be interpretedas a true predator instead of a parasite, especially considering the unusual mode of attachment. We briefly review interactionsof lacewing larvae with other organisms represented in amber from Myanmar and add two new pieces to thepuzzle of reconstructing the trophic interactions in the 100-million-year old amber forest.

Crustacean larvae are usually recognised as small organisms, below one millimeter body size. However, in different crustacean groups such as Stomatopoda, Polychelida, or Achelata, also very large larvae occur with sizes of 20 mm and beyond. Also from few meiuran species (“short-tailed” crustaceans, including crabs, hermit crabs, or squat lobsters), rather large larvae are known, though still considerably smaller than 20 mm. We present here two specimens of anomalan meiuran larvae, each with a total length of 24 mm, which by far exceed the previously known/reported maximum sizes of meiuran larvae. Yet, both specimens exhibit characters that indicate their identity as zoea larvae (first larval phase with several stages), most likely shortly before the metamorphosis to the megalopa (second larval phase with one stage). Due to this early developmental state, it is difficult to provide a narrower systematic identification of the larvae. In addition to the description of the developmental status of all appendages, we also investigated the gizzard and especially the compound eyes. The latter possess a mixture of hexagonal, intermediate, and square-shaped facets in an unusual arrangement. We documented the exact arrangement of the facets in both specimens and discuss the possible re-structuring during metamorphosis. The arrangement of the different types of facets indicates that transformation to an adult eye structure takes place over several moults and that the facets are being rearranged in this process. The findings demonstrate that also meiuran larvae contribute to the fraction of the macro-plankton.

Neuroptera is one of the smaller ingroups of Holometabola, the ingroup of Insecta characterised by “complete” metamorphosis. Neuroptera comprises about 6000 species in the modern fauna, but appears to have been more diverse in the past. While adults distantly resemble certain moths or damselflies, the larval forms of Neuroptera are mostly fierce predators with prominent venom-injecting stylets. The most well-known of these larvae are probably those of antlions. Antlions and their closer relatives (silky lacewings, split-footed lacewings, ribbon-winged lacewings, spoon-winged lacewings, and owlflies) form a distinct monophyletic ingroup of Neuroptera, Myrmeleontiformia, hence the antlion-like forms. The fossil record of antlion-like larvae dates back far into the Cretaceous; many forms are known by exceptionally wellpreserved specimens entrapped in amber. The oldest fossil record of a neuropteran larva (not an antlion-like form) comes from Lebanese amber. Interestingly, the supposedly oldest record of an antlion-like larva is preserved in rock and comes from the famous Lower Cretaceous Crato Formation. We re-evaluate this fossil based on high-resolution composite photography. Due to the non-availability of many key characters, standard procedures for identifying the specimen to a more narrow ingroup remains challenging. Therefore, we used a morphometric approach. A combination of non-metric multidimensional scaling (NMDS), parallel coordinate plots and discriminant function analysis indicates that the fossil is a representative of the group Ascalaphidae (owlflies) + Myrmeleontidae (antlions). We discuss implications of this result for the fossil record of neuropteran larvae. These include the rather derived morphology of the oldest fossil larva of Myrmeleontiformia in contrast to previous expectations. Furthermore, fossils from soil dwellers can not only be expected to be found in amber, but also as compression fossils.

Larvae of the group Holometabola (beetles, wasps, flies, moths and others) differ significantly in their morphology from their corresponding adults. In most larvae, appendages and other structures protruding from the body (antennae, palps, legs, trunk processes) appear less elongate than in their corresponding adults, providing the impression that these larvae are restricted to a certain degree in developing more elongate structures. We provide here numerous counterexamples of larvae of lacewings (Neuroptera). These include different forms of elongated antennae, mandibles, maxillae, labial palps, legs, trunk processes and neck regions. Most of these examples are larvae preserved in different types of 100 million-year-old amber. The longest neck region was found in an extant specimen. All these examples demonstrate that certain branches of Neuroptera indeed had larval forms that possessed strongly elongated structures. Hence there is no principal constraint that hinders holometabolan larvae to develop such structures.

Lacewing larvae (Neuroptera) are known to be fierce predators which are morphologically highly specialised for a raptorial lifestyle. Mandibular-maxillary stylets are characteristic for all larvae of this group; these stylets can be extraordinarily massive. Despite these distinct sucking-piercing stylets, also other extreme features occur in some ingroups, such as an extremely elongated neck. In larvae of thread-winged lacewings (Crocinae) the neck can reach up to about one third of the body length; they are also called ‘long-necked antlions’. Even though the larvae of living neuropteran species show a variety of conspicuous morphologies today, indeed 100 million years ago, in the Cretaceous, Neuroptera seems to have had an even more “experimental phase”. Several larval specimens are known so far especially in Myanmar, Spanish and Lebanese amber from the Cretaceous with unique and unusual character combinations not found in any group living today. We describe here ten new fossil findings of one of these types of larvae with elongated head capsule in Myanmar amber, previously only known from a single specimen. We compared the head shapes of the new specimens with those of 190 specimens of other lacewing larvae and discuss further implications of our findings, especially making functional comparisons with long-necked antlions.

Neuroptera, the group of lacewings, comprises only about 6000 species in the modern fauna, but is generally assumed to have been more diverse and important in the past. A major factor of the modern-day ecological diversity of the group, and supposedly in the past as well, is represented by the highly specialised larval forms of lacewings. Quantitative analyses of the morphology of larvae revealed a loss of morphological diversity in several lineages. Here we explored the diversity of the larvae of mantis lacewings (Mantispidae), lance lacewings (Osmylidae), beaded lacewings (Berothidae and Rhachiberothidae, the latter potentially an ingroup of Berothidae), and pleasing lacewings (Dilaridae), as well as fossil larvae, preserved in amber, resembling these. We used shape analysis of the head capsule and stylets (pair of conjoined jaws) as a basis due to the high availability of this body region in extant and fossil specimens and the ecological importance of this region. The analysis revealed a rather constant morphological diversity in Berothidae. Mantispidae appears to have lost certain forms of larvae, but has seen a drastic increase of larval diversity after the Cretaceous, this is in contrast to a significant decrease in diversity in adult forms.

Interactions between animals and plants represent an important driver of evolution. Especially the group Insecta has an enormous impact on plants, e.g., by consuming them. Among beetles, the larvae of different groups (Buprestidae, Cerambycidae, partly Eucnemidae) bore into wood and are therefore called wood-borer larvae or borers. While adults of these beetle groups are well known in the fossil record, there are barely any fossils of the corresponding larvae. We report here four new wood-borer larvae from Cretaceous Kachin amber (Myanmar, ca. 99 Ma). To compare these fossils with extant wood-borer larvae, we reconstructed the body outline and performed shape analysis via elliptic Fourier transformation and a subsequent principal component analysis. Two of the new larvae plot closely together and clearly in the same area as modern representatives of Buprestidae. As they furthermore lack legs, they are interpreted as representatives of Buprestidae. The other two new larvae possess legs and plot far apart from each other. They are more difficult to interpret; they may represent larvae of early offshoots of either Cerambycidae or Buprestidae, which still retain longer legs. These findings represent the earliest fossil record of larvae of Buprestidae and possibly of Cerambycidae known to date.

Antlion-like lacewings (Myrmeleontiformia) have comparably large predatory larvae; most well-known are the larvae of antlions (Myrmeleontidae) and owlflies (Ascalaphidae). Yet, larvae of spoon-winged lacewings (Nemopterinae, also an ingroup of Myrmeleontiformia) are less well studied and differ in their overall habitus, with a broader head and stouter mouthparts. We here review the known record of spoon-winged lacewing larvae and report two new fossil larvae preserved in 99 million-year-old Kachin amber from Myanmar that have some characteristics of spoon-winged lacewing larvae. We quantitatively compare morphological aspects of all these larvae with those from other myrmeleontiformian larvae. Our analyses suggest that one fossil larva may indeed be closely related to extant spoon-winged lacewings, but retains some plesiomorphies shared with Crocinae, the sister group of Nemopterinae. The other larva shows many unique features, but also some similarities to spoon-winged lacewing larvae, hence might be a highly specialised early representative of the lineage. These two larvae are the first potential larvae of Nemopterinae in the fossil record. Therefore, they are important indicators for the structure of the early diversification of lacewings.

Summary Aquatic larvae are known in three early branches of Pterygota: Ephemeroptera (mayflies), Plecoptera (stoneflies), and Odonata (dragonflies, damselflies). A common origin of these larvae has been suggested, yet also counterarguments have been put forward, for example, the different position of larval gills: laterally on the abdomen in Ephemeroptera, terminally in Odonata, variably in Plecoptera. We discuss recent fossil findings and report a new dragonfly-type larva from Kachin amber (Myanmar), which possesses ancestral characters such as a terminal filum, maintained in ephemeropterans, but lost in modern odonatan larvae. The new larva possesses lateral protrusions on the abdominal segments where in other lineages gills occur. Together with other fossils, such as a plecopteran retaining lateral gills on the abdomen, this indicates that lateral protrusions on the abdomen might have well been an ancestral feature, removing one important argument against the idea of an aquatic larva in the ground pattern of Pterygota., Graphical abstract, Highlights • A new dragonfly-type larva was found in Kachin amber (Myanmar, 99 million years old). • The larva possesses a terminal filum, which is not known in modern dragonfly larvae • It also exhibits lateral abdominal protrusions where in other lineages gills occur • This find makes an aquatic larva in the ground pattern of Pterygota more likely, Paleontology; Entomology; Evolutionary history; Paleobiology

Representatives of Hippoidea, often called sand crabs or mole crabs, are an ingroup of Anomala. These marine crustaceans inhabit the tropical and subtropical coasts of the world, yet some also appear in temperate climates. Their adults are specialized for digging and living in sandy substrates. Hippoidean zoea-type larvae are planktic and reach large sizes up to a few centimetres. These larvae transform into megalopa larvae, strongly resembling the adult, mediating the transition to the benthic lifestyle of the adult. We reconstructed outlines in dorsal view of over 80 shields of hippoideans, including representatives of Blepharipodidae (sister group to all others), Albuneidae, and Hippidae and including adults, megalopa-type, and zoea-type larvae from all three ingroups. We conducted a morphological analysis on this data using an elliptic Fourier transformation and principal component analysis. We used the results of the analysis to discuss the life history of hippoideans and the special function of megalopae, which often lack emphasis in current research. Early stage zoea larvae, megalopae, and adults show a linear gradient in their morphological development according to our analysis. However, late stage zoea larvae deviate from this pattern, possibly due to their specialization to a long-lasting planktic life. Lastly, we discuss the influence of phenotypic plasticity in hippoidean zoea larvae.

Modern crustaceans are extremely diverse, not only in their morphologies, but also in their life styles. It is therefore not surprising that parasitism evolved in various lineages of Eucrustacea independently, in groups such as amphipodan, isopodan and copepodan crustaceans, but also barnacles and fish lice. Parasitic crustaceans have become specialized to many different host species and show a wide variety of attachment and feeding specializations. Among the parasitic crustaceans, different groups are especially interesting to study for reconstructing the evolution of parasitism within this group. This chapter summarizes the modern aspects, evolutionary history and fossil record of parasitic crustacean groups. By reviewing the parasitic crustaceans with emphasis on their fossil record, this chapter aims to improve our understanding of parasitism in general.

Larvae of Brachypsectridae (Texas beetles) have often been considered rare. However, they are known from North America, Asia and Australia in the extant fauna, and from Miocene, Eocene and Cretaceous ambers. We review the overall record of extant and fossil larvae of Brachypsectridae represented in the literature. Furthermore, we present three new specimens, which were all documented via light microscopy. Two of the specimens are from Baltic amber, and the third one is from the Cretaceous amber of Myanmar; the latter was additionally documented via synchrotron radiation micro-computed tomography. The number of known extant specimens, more than 20, is unusually high compared to other small groups of beetles and with respect to the low number of eight formally described species. The number of fossil specimens from the Miocene, Eocene and Cretaceous is low, two to three specimens per time slice. This makes a comparison of morphological diversity difficult. Still such an analysis of overall body shape as well as of the anterior body region revealed no significant quantitatively recognisable changes over time. However, some qualitative changes in the morphology of the antenna and lateral processes from the Cretaceous to younger faunas could be identified.

Within Neuroptera, the group of lacewings, the ingroup Nevrorthidae is special in several aspects: 1) the group may represent the sister group to all other neuropterans; 2) the group is quite species-poor with only 19 extant species known so far; 3) its representatives show a disjunct relict distribution; 4) it has very unusual appearing larvae. These larvae are very elongate, almost worm-shaped. Our overall knowledge of these larval forms is still very limited. We here review all known occurrences of extant larvae, amended by fossil larvae, all preserved in amber. So far there have been only 17 extant larval specimens of Nevrorthidae depicted in the literature. We also present new fossil larvae, with this reaching a total number of 16 known fossil larvae of Nevrorthidae. When plotting measured lengths, larvae cluster into more than three clusters. Also reconstructed size gains between these clusters indicate that Nevrorthidae might in fact develop through more than three larval stages, unlike other lacewings. A special subdivision of the trunk segments observed in many larvae indicates a specialisation for moving in confined spaces. Comparison of syn-inclusions and literature data make it likely that not all larvae lived in running waters, as previously assumed. Overall our knowledge remains rather limited, yet the data allow to draw some new conclusions about the life and evolution of these larval forms., Fragmenta Entomologica, Vol. 52 No. 2 (2020)

Ant mimicry, i.e., the mimicking of ant workers by another organism, is a widespread phenomenon among different groups of Euarthropoda, including spiders and different insect species. One example of ant mimicry occurs among praying mantises (Mantodea); here the first stage nymphs have been recorded to perform ant mimicry. In this study, we investigated different nymphal instars of Miomantis binotata for possible morphological similarities to ants. The different instars were compared as stages supposed to perform ant mimicry would differ morphologically from those stages not supposed to resemble ants. The specimens were investigated under different microscopic settings and measurements were performed. Our results do not show significant differences concerning morphological measurements or shape of structures between the different nymphal instars of M. binotata. One prominent difference between stage one nymphs and later stages occurs in the colouration of the body, which is very dark in the earliest nymph. This difference might explain why young nymphs of Miomantis binotata are interpreted as ant-mimicking, despite the apparent lack of other morphological resemblances., Fragmenta Entomologica, Vol. 52 No. 1 (2020)

Dictyoptera, which comprises cockroaches, termites and mantids, is a quite successful group of insects in evolutionary terms with a long fossil record—roachoid insects were already abundant 315 million years ago in the Carboniferous forests. One of the most remarkable autapomorphies of extant dictyopterans, and possibly a major factor for their persisting success, is the ability to produce oothecae. Despite the robustness of this sort of egg package, fossils of oothecae are very rare, the oldest direct evidences being from the Cretaceous Crato Formation in Brazil (115 mya). The ability to produce oothecae is presumably linked to a specific ovipositor morphology, including a significant length reduction. Hence, ovipositor morphology can indirectly inform about the reproductive strategy of a species. Herein we describe the ovipositor morphology of various fossil forms of dictyopteran insects. Early fossil roachoids, in contrast to the modern forms, possessed a very long and prominent ovipositor, reminiscent of the ovipositor in orthopterans (Ensifera), indicating that these forms laid individual, rather small eggs into a substrate. We present examples from different fossil deposits, which show the entire range of ovipositor morphologies, from very long forms over forms with ovipositors partly reduced in length to modern-appearing morphologies. Most remarkably, different shapes of ovipositors seem to be present in roachoids in the fauna of the 115 million years old Crato Formation—species with long prominent ovipositors co-existed with species with a reduced short and broad ovipositor. Additionally, females that carry oothecae attached to their abdomen indicate a third type of ovipositor: a further reduced ovipositor as seen in modern forms, which already allowed the internal production of oothecae.

Kazacharthrans are exclusively fossil crustaceans restricted to the Triassic and possibly Jurassic period and were first described by Tchernyshev in 1940. Kazachartha is supposed to represent the sister group to Notostraca (tadpole shrimps). Little is known about the morphology of most kazacharthrans, and in general only few publications are available. We present here a specimen with kazacharthan-related traits, which we compare to the co-occurring species Notostraca minor (formerly Triops cancriformis minor), a notostracan representative. Both specimens come from the Museum Terra Triassica in Euerdorf, Lower Franconia, southern Germany and were documented using cross-polarized light and autofluorescence settings to achieve well contrasted, high-resolution images. Key morphological features of the kazacharthran-like specimen are the very broad shield without a dorsal midline and spines, a broad and elongated posterior trunk and a square-shaped telson with lateral bulges. Also some details, like different eye structures, mandibular and cervical groove, intestine, and the paired shell glands are visible. Comparison to Notostraca minor revealed differences in these morphological features between the two specimens. We suggest an interpretation of the presented specimen near Kazacharthra due to the described features and discuss the importance of the specimen for branchiopodan phylogeny and biogeography.

Xiphosurans have often been considered as archaic appearing cheliceratan arthropods, with a rich fossil record. We describe here parts of the post-embryonic ontogeny of the 300 million year old xiphosuran Euproops danae (Xiphosura sensu stricto, Euchelicerata), from the Mazon Creek Lagerstätte (Upper Carboniferous), USA. Recently, the ontogeny of a closely related species, Euproops sp. from the Upper Carboniferous Piesberg quarry, Osnabrück, Germany (informally called 'Piesproops'), has been reconstructed. This analysis has drawn characters into question that were used to differentiate E. danae from another species occurring at the same time, Euproops rotundatus from the British Middle Coal Measures. More precisely, early post-embryonic stages of Piesproops resemble E. danae; later stages resemble E. rotundatus. Based on this earlier study, the here-described reinvestigation of E. danae has been performed as the ontogenetic sequence itself may yield more reliable characters for differentiating species of Euproops. We could identify eight different growth stages for E. danae. This ontogenetic sequence shows a comparable growth to that of Piesproops, but differs markedly in the development of the opisthosomal flange. This character may serve as a basis for reliably differentiating these species. Additionally, analysing the ontogeny of further species may offer the basis for identifying heterochronic shifts in the evolution of xiphosurans.

Holometabolous insects represent a mega-diverse group of organisms that are dominant in most terrestrial faunas. All holometabolous insects develop via a specific transitory stage between the last larval stage and the adult, called the pupa. While insects in general have a comparably good fossil record, fossils of pupae of holometabolous insects are relatively rare. We report here four pupal specimens preserved in a single piece of amber. These represent pupa stages of assassin flies, Asilidae, and are most likely representatives of Laphriinae. While dipterans are quite common in the fossil record, especially in amber, representatives of Asilidae are comparably rare. Combining the rarity of the systematic group and the rarity of the specific life stage, these fossil remains of assassin fly pupae are extremely unusual;to date only a single specimen has been depicted in the literature. We discuss the importance of our new finding and possible interpretations regarding behavioural aspects of the group enclosed in amber.

We present a documentation of the morphological details of two larval stages of mantis shrimps. Documentation was done using the autofluorescence capacities of the cuticle. This is the first time that morphological details of late mantis shrimp larvae are documented in great detail via photography, including all parts of the body up to the proximal elements of the appendages, and not presented as line drawings; it is the second time for mantis shrimp larvae in general. The description is presented as a standardized descriptive matrix. Documentation and description style are adjusted to facilitate comparison with fossil representatives of mantis shrimps, but also their extant counterparts, as well as specimens in the wider framework of Malacostraca and Eucrustacea. Through an exemplary comparison with fossil mantis shrimps, we provide indications about the early evolutionary history of the group. Through an out-group comparison, we identify several possible evolutionary changes of developmental timing, i.e., heterochrony, which could explain some morphological specialisations of mantis shrimps.

International audience; Psychopsidae (silky lacewings) is a species-poor ingroup of Neuroptera. Silky lacewings show a distinct relic distribution, indicating that the group was more species-rich and diverse in the past. Silky lacewings have distinct larvae that resemble antlion larvae but differ from these in lacking teeth on their mouth parts, and in having a projecting labrum, which makes them “long-nosed antlion larvae”. These larvae are well known from Myanmar amber (about 100 mya) and Baltic amber (mostly 34-38 mya, possibly 23-48 mya), as well as from the extant fauna. We report and figure numerous additional specimens from both amber types and from ca. 100 mya old French Charentese amber, expanding the known record of well-illustrated extant and fossil specimens from 26 to 52 specimens. We compare the diversity of head shape among these larvae through time by outline analysis. Results indicate that morphological diversity was pronouncedly higher in the Cretaceous, even after sample size correction. Eocene representatives are more diverse than modern representatives, but less diverse than Cretaceous ones, in one shape aspect that explains most of the overall variation (55.7%). Eocene representatives are less diverse in another shape aspect that explains the second-most variation (26.9%), but this might reflect a lack of first larval stage specimens. There seems to be no strong correlation between size and shape. This type of analysis enables a test for the loss of diversity over time, based on morphological diversity as a proxy, without the requirement of identifying fossil larvae down to a narrow taxonomical range.

Larvae, and especially fossil larvae, are challenging to deal with from a purely taxonomic view. Often one cannot determine which species the larvae belong to. Yet, larvae can still contribute to various scientific questions. Especially morphological traits of a fossil larva can be highly informative for reconstructing character evolution. Also the occurrence of specific larval types and larval characters in time and the disappearance of such forms can well be reconstructed also without being able to narrow down the phylogenetic relationship of a larva very far. Here, we report two new beetle larvae preserved in Baltic amber which are identified as representatives of Scraptiidae, based on an enlarged terminal end (‘9th abdomen segment’); this is only the third record of such larvae. In comparison to modern forms, the terminal ends of the two new fossil larvae is even larger in relation to the remaining body than in any known larva. Unfortunately, our knowledge of such larvae in the modern fauna is very limited. Still, one of the two already known fossil larvae of Scraptiidae also has a very long terminal end, but not as long as those of the two new fossils. These three fossil larvae therefore seem to possess a specific morphology not known from the modern fauna. This might either mean that they (1) represent a now extinct larval morphology, a phenomenon well known in other euarthropodan lineages, or that (2) these forms represent a part of the larval phase not known from modern day species as they have not been described yet; such cases occur in closely related lineages. In any case, the fossils expand the known diversity of larval morphologies.

The group Xiphosurida (horseshoe “crabs”) is today only represented by four species. However, in the fossil record, several dozen species have been described, especially from the Carboniferous (about 300 million years ago). Several species have been interpreted as representatives of Euproops or Belinurus, but there is ongoing discussion which of these species are valid and how they can be differentiated. Recent studies suggested that differences in the timing of individual development could provide information for species distinction, exemplified by studies on Euproops danae (Mazon Creek, USA) and Euproops sp. (“Piesproops”; Piesberg, Germany). For this study, we reinvestigated all Carboniferous xiphosurids from the British Coal Measures stored in the collections of the Natural History Museum London. Size comparisons of the specimens revealed nine size groups; the smaller specimens were originally labelled as Belinurus, the larger ones as Euproops. The nine size groups exhibit five different morphotypes differing in structures surrounding the posterior shield (= thoracetron): spines of different lengths and, in larger specimens, a more or less developed flange. Two of these morphotypes show significantly longer spines than the remaining specimens and could be conspecific as E. anthrax. The remaining specimens are interpreted as growth series of another species, presumably of E. rotundatus. An ontogenetic flange formation is also known from E. danae and the “Piesproops”, but the timing differs between all three species. In E. rotundatus, the flange develops rather late, but then comparably abruptly, which makes this development more metamorphic in relation to development in the other species.

Background Calmanostraca is a group of branchiopod eucrustaceans, with Triops cancriformis and Lepidurus apus as most prominent representatives. Both are regularly addressed with the inaccurate tag “living fossil”, suggesting that the morphology has remained stable for several millions of years. Yet, T. cancriformis and L. apus represent only a fraction of the morphological diversity occurring in Calmanostraca, comprising the two groups Notostraca and Kazacharthra. Notostracans, commonly called tadpole shrimps, comprise the two groups Lepidurus and Triops with their elongated and rather narrow (in dorsal view) head shields. Kazacharthrans are exclusively fossil calmanostracans with broad and rather short shields, known from the Jurassic and Triassic period. One formation where fossil calmanostracans have been found is the Yixian Formation of northeastern China (Lower Cretaceous, 125–121 million years). It is part of the Jehol Group, an ecosystem known for its exceptionally well-preserved fossils, including vertebrates and plants, but also diverse arthropods. Two calmanostracan species have to date been described from the Yixian Formation, Jeholops hongi and Chenops yixianensis. Results We describe here a new calmanostracan crustacean from the Yixian Formation, Notostraca oleseni, and additionally a simple tool using a morphospace analysis to delineate different species. Measurements characterising the shield and trunk proportions of different calmanostracan species were performed, data were size-corrected, and used for this morphospace analysis to compare the different morphologies. As sclerotised body parts are more likely to be preserved in fossils than soft tissue, shields and parts of the trunk are in many cases the only morphological structures available for study. Therefore, the present analysis represents a simple tool for distinguishing between different species, as well as allowing the inclusion of specimens that are only preserved fragmentarily. Additionally, it provides a tool to demarcate the kazacharthran-like specimen described, but not formally named, by Wagner et al. (Paleontol Res. 22:57–63, 2018). Hence, we amended the description and name the species Calmanostraca hassbergella. Conclusion Our results indicate a large diversity in shield and trunk morphology in calmanostracans, in contrast to their often claimed highly conserved and uniform morphology. Especially extinct forms such as Notostraca oleseni add up to this result and point to the species richness and morphological diversity within Calmanostraca.

The enigmatic Mesoprosopon triasinum from the Triassic Hallstatt Limestone of Austria, which was once considered to be either a representative of Brachyura or Cycloidea, is re-interpreted herein as a eumalacostracan larva and is the oldest of its type known to date. It shows a mixture of characters that are typical of the zoea stages of certain meiuran ingroups (e.g., Hippidae) or of erichthus-type larvae of stomatopods. Four long spines evidently provided additional buoyancy to counteract the comparatively heavy load of a calcified shield. Additionally, a distinct ventral gape might imply that the animal was able to enrol into a tight ball. Our recognition of specimens of M. triasinum as larval stages, rather than adults, may have a major impact on the re-study of some still poorly known cycloids. In the future, the term "mesoprosopon" may be salvaged as the name of this type of larva. (C) 2016 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

For understanding the life habits of extinct organisms, functional morphology is of crucial importance. In arthropods, the morphology of the appendages in particular gives insights into the mode of life. Yet, in the fossil record of arthropods mainly dorsal structures are preserved, as they are often more sclerotised or even mineralised. Exceptions are, for example, the species of Naraoia from the Cambrian Burgess Shale (about 508 million years old), of which the appendages are also preserved. We present here new details of the appendages of Naraoia compacta, which were made visible with modern imaging methods that were not yet available during former investigations. According to our re-study, the appendage shows a division into basipod, endopod and exopod. The basipod-body joint has not been visible to earlier investigators, and both basipod and endopod are significantly more strongly adorned than previously interpreted. The most important difference to earlier studies regards our interpretation of the exopod morphology. According to our new data, the exopod is composed of a series of similar, small paddles attached to a shaft, and not feather-like in appearance. This morphology has a strong impact on the swimming behaviour of N. compacta, as the paddles can be closed to form a functionally single large paddle during the power stroke, and will be opened during the recovery stroke to reduce the water drag. In this way, our new data provide important insights into the life habits of this long extinct species.

Holometabola is a hyperdiverse group characterised by a strong morphological differentiation between early post-embryonic stages (= larvae) and adults. Adult forms of Holometabola, such as wasps, bees, beetles, butterflies, mosquitoes or flies, are strongly differentiated concerning their mouth parts. The larvae most often seem to retain rather plesiomorphic-appearing cutting-grinding mouth parts. Here we report a new unusual larva preserved in Burmese amber. Its mouth parts appear beak-like, forming a distinct piercing mouth cone. Such a morphology is extremely rare among larval forms, restricted to those of some beetles and lacewings. The mouth parts of the new fossil are forward oriented (prognathous). Additionally, the larva has distinct subdivisions of tergites and sternites into several sclerites. Also, the abdomen segments bear prominent protrusions. We discuss this unusual combination of characters in comparison to the many different types of holometabolan larvae. The here reported larva is a new addition to the ‘unusual zoo’ of the Cretaceous fauna including numerous, very unusual appearing forms that have gone extinct at the Cretaceous–Palaeogene boundary.

Background Adult mantis lacewings, neuropteran holometabolan insects of the group Mantispidae, possess anterior walking legs transformed into prey-catching grasping appendages reminiscent of those of praying mantises. While adult mantis lacewings are hence active “wait-and-catch” predators, the larvae of many mantis lacewings have a quite different biology: first-stage larvae seek out female spiders, mount them, and either wait until the spider has produced an egg sac or, in some cases, choose a female already bearing an egg sac. The larva then enters the egg sac and feeds on the eggs. While first stage larvae are highly mobile with comparably long legs and a certain degree of dorso-ventral flattening (“campodeiform”), larval stages two and three are almost immobile, grub-like, and simply remain within the egg sac. Fossils of mantis lacewings are relatively rare, fossils of larval mantis lacewings are even rarer; only a single larva sitting on a juvenile spider has been described from ca. 50 million year old Baltic amber. Results Here we describe a second occurrence of a larval mantis lacewing from significantly older Burmese amber, about 100 million years old. The specimen is preserved in a position right at the leg of a spider, similar to modern-day larvae that are about to mount their prospective host. The claws of the larva can be seen to grab around the leg of the spider. Conclusions We discuss how reliable these fossils are as indicators of palaeo-parasitism, and in which aspects the behaviour of mantis lacewing larvae in general indeed represents parasitism. While the specimen appears to be about to board the spider, it may not necessarily represent a parasite in the strict sense. Evaluating the actual ecological role of a fossil heavily depends on comparison to modern forms, and not all modern-day larvae of Mantispidae are parasites. We therefore provide a closer look into the known feeding habits of modern mantis lacewing larvae.

Mantis shrimps are prominent predatory crustaceans. Their larvae, although morphologically very differently-appearing from their adult counterparts, are already predators; yet, unlike the adults they are not benthic. Instead they are part of the plankton preying on other planktic organisms. Similar to some types of lobsters and crab-like crustaceans the planktic larvae of mantis shrimps can grow quite large, reaching into the centimeter range. Nonetheless, our knowledge on mantis shrimp larvae is still rather limited. Recently new types of giant mantis shrimp larvae with “extreme morphologies” have been reported. Here we describe another type that qualifies to be called “extreme”. Comparative measurements of certain morphological structures on selected known larvae support the exceptionality of the new specimen. It differs in several aspects from the original four types of extreme mantis shrimp larvae described by C. Haug et al. (2016). With this fifth type we expand the known morphological diversity of mantis shrimp larvae and also contribute to our still very incomplete, although growing, knowledge of this life phase.

Parasites are found in all habitats and within all groups of animals, and their influence on food webs, ecosystems and evolutionary development is significant. However, the fossil record of direct parasitism is very scarce. We present here probable examples of parasitic isopods on fishes from the Upper Jurassic Solnhofen Lithographic Limestones (150 million years old, southern Germany). Individual fishes appear to be infested with one to three isopods each. All specimens were documented with up-to-date imaging methods (macrophotography, stereo-photography, composite imaging). Position, orientation and other aspects clearly indicate that the isopods were already attached to the fishes before they died and hence do not represent scavengers but (more or less permanently) attached parasites. While the morphology of the specimens is somewhat uninformative about the systematic position of the isopods, their specific type of parasitism is an indicator for a position in the early lineage towards Cymothoidae. This would represent the first fossil record of this group of obligate fish parasites.

We re-investigated the fossil species tenera Oppel, 1862, an achelatan lobster (traditionally named Palinurina tenera) found in 150 million years old limestones of southern Germany. All known specimens attributed to this species show a mixture of characters, which in modern forms occur either in larvae or post-larval juveniles. Hence these specimens provide insight into a phase in ontogeny that is no longer present in the developmental sequence of any modern achelatan lobster, as the latter ones skip this phase and replace it by a drastic metamorphosis. Comparable cases have been described earlier, yet did only comprise single stages or two successive ones at most. In the here described case four developmental stages are preserved. The reconstructed ontogeny of tenera therefore represents the currently best known sequence of an early achelatan lobster that covers this specific intermediate phase. The largest known stage most likely still represents an immature of a yet undiscovered adult. These findings support the interpretation that early achelatan lobsters developed in a more gradual ontogenetic sequence than modern forms. It furthermore demonstrates that it was even more gradual than anticipated previously.

Mantodeans or praying mantises are flying insects and well known for their raptorial behaviour, mainly performed by their first pair of thoracic appendages. We describe here a new, exceptionally preserved specimen of the early mantodeanSantanmantis axelrodiGrimaldi, 2003 from the famous 110 million years old Crato Formation, Brazil. The incomplete specimen preserves important morphological details, which were not known in this specific form before for this species or any other representative of Mantodea. Unlike in modern representatives or other fossil forms of Mantodea not only the first pair of thoracic appendages shows adaptations for predation. The femora of the second pair of thoracic appendages bear numerous strong, erect spines which appear to have a sharp tip, with this strongly resembling the spines of the first pair of thoracic appendages. This indicates that individuals ofS. axelrodilikely used at least two pairs of thoracic appendages to catch prey. This demonstrates that the prey-catching behaviour was more diverse in early forms of praying mantises than anticipated.

The early fossil record of insects is scarce, with only few finds in the Devonian. All these finds appear problematic and controversial, partly due to incomplete preservation and challenging interpretation of many structures. We provide details of one of these important forms,Rhyniognatha hirstifrom the famous Rhynie Chert Lagerstätte with up-to-date 3D imaging techniques. The fossil has been interpreted as the remains of one of the earliest flying insects. The specimen mainly preserves the remains of the head. The structures of the mandibles have been used as a main argument for an interpretation as an insect, but these are in fact less easy to interpret. New observed structures include the remains of a head capsule and an additional pair of mouth parts. Structures formerly suggested to represent remains of the head capsule or apodemes are more likely to be representing glands of ectodermal origin. The newly observed structures do not support an interpretation as an insect. Instead they make the interpretation as a myriapod more likely, possibly as a centipede. Centipede remains from the Rhynie Chert are known from scutigeromorphs. We therefore point out thatR. hirsticould be interpreted as an early centipede.

We describe a possible new defensive behaviour of larval stages of mantis shrimps (Stomatopoda). Mantis shrimp larvae are rarely observed in nature, thus the study is based on postures of museum material and functional morphological aspects. Specimens described here are tightly enrolled, their pleon is bent forward, and the telson is locked into the frontal margin of the shield. This margin has two lobes into which the two posterolateral spines of the telson fit. The shield shows further adaptions to enrolment; e.g., the ventral gape of the shield perfectly matches the width of the pleon and leaves no major gaps when the pleon is bent forward. Based on these observations, we briefly discuss the possibilities to infer behavioural aspects from functional morphological aspects. Enrolment in modern day organisms is primarily known from terrestrial arthropods, e.g., pill bugs and pill millipedes, but in the Palaeozoic it was mainly performed by marine organisms such as trilobites, agnostines and their relatives. Stomatopod larvae that appear to be able to perform enrolling in a marine environment are therefore a potential functional equivalent for better understanding the functional aspects of enrolment in extinct marine arthropods.

Modern achelate lobsters, slipper and spiny lobsters, have a specific post-embryonic developmental pattern with the following phases: phyllosoma, nisto (slipper lobsters) or puerulus (spiny lobsters), juvenile and adult. The phyllosoma is a peculiar larva, which transforms through a metamorphic moult into another larval form, the nisto or puerulus which largely resembles the juvenile. Unlike the nisto and puerulus, the phyllosoma is characterised by numerous morphological differences to the adult, e.g. a thin head shield, elongate appendages, exopods on these appendages and a special claw. Our reinvestigation of the 85 million years old fossil "Eryoneicus sahelalmae" demonstrates that it represents an unusual type of achelatan lobster larva, characterised by a mixture of phyllosoma and post-phyllosoma characters. We ascribe it to its own genus: Polzicaris nov. gen. We study its significance by comparisons with other cases of Mesozoic fossil larvae also characterised by a mixture of characters. Accordingly, all these larvae are interpreted as ontogenetic intermediates between phyllosoma and post-phyllosoma morphology. Remarkably, most of the larvae show a unique mixture of retained larval and already developed post-larval features. Considering the different-and incompatible-mixture of characters of each of these larvae and their wide geographical and temporal distribution, we interpret all these larvae as belonging to distinct species. The particular character combinations in the different larvae make it currently difficult to reconstruct an evolutionary scenario with a stepwise character acquisition. Yet, it can be concluded that a larger diversity of larval forms and developmental patterns occurred in Mesozoic than in modern faunas.

The larval phase of metazoans can be interpreted as a discrete post-embryonic period. Larvae have been usually considered to be small, yet some metazoans possess unusually large larvae, or giant larvae. Here, we report a possible case of such a giant larva from the Upper Jurassic Solnhofen Lithographic limestones (150 million years old, southern Germany), most likely representing an immature cirripede crustacean (barnacles and their relatives). The single specimen was documented with up-to-date imaging methods (macro-photography, stereo-photography, fluorescence photography, composite imaging) and compared with modern cirripede larvae. The identification is based on two conspicuous spine-like extensions in the anterior region of the specimen strongly resembling the so-called fronto-lateral horns, structures exclusively known from cirripede nauplius larvae. Notably, at 5 mm in length the specimen is unusually large for a cirripede nauplius. We therefore consider it to be a giant larva and discuss possible ecological and physiological mechanisms leading to the appearance of giant larvae in other lineages. Further findings of fossil larvae and especially nauplii might give new insights into larval evolution and plankton composition in the past.

Larvae of malacostracan crustaceans represent a large fraction of modern day zooplankton. Plankton is not only a major part of the modern marine ecosystem, but must have played an important role in the ecosystems of the past as well. Unfortunately, our knowledge about plankton composition of the past is still quite limited. As an important part of today’s zooplankton, malacostracan larvae are still a rarity in the fossil record; many types of malacostracan larvae dominating the modern plankton have so far not been found as fossils. Here we report a new type of fossil malacostracan larva, found in the 150 million years old lithographic limestones of southern Germany (Solnhofen Lithographic Limestones). The three rather incomplete specimens mainly preserve the telson. A pronounced middle spine on the posterior edge of these specimens indicates that they are either larval forms of a clawed lobster or of an axiidean lobster, or of a closer relative to one of the two groups. The tergo-pleura are drawn out into distinct spines in one specimen, further supporting the interpretation as a larva of a clawed lobster or an early relative. The telson morphology also shows adaptations to a prolonged planktic life style, the latero-posterior edges are drawn out into distinct spines. Similar adaptations are known in larvae of the modern homarid lobsterNephrops norvegicus, not necessarily indicating a closer relationship, but convergent life styles. The new finds provide an important new insight into the composition of Mesozoic zooplankton and demonstrate the preservation potential of lithographic limestones.

Holometabolous insects are the most diverse, speciose and ubiquitous group of multicellular organisms in terrestrial and freshwater ecosystems. The enormous evolutionary and ecological success of Holometabola has been attributed to their unique postembryonic life phases in which nonreproductive and wingless larvae differ significantly in morphology and life habits from their reproductive and mostly winged adults, separated by a resting stage, the pupa. Little is known of the evolutionary developmental mechanisms that produced the holometabolous larval condition and their Paleozoic origin based on fossils and phylogeny.We provide a detailed anatomic description of a 311 million-year-old specimen, the oldest known holometabolous larva, from the Mazon Creek deposits of Illinois, U.S.A. The head is ovoidal, downwardly oriented, broadly attached to the anterior thorax, and bears possible simple eyes and antennae with insertions encircled by molting sutures; other sutures are present but often indistinct. Mouthparts are generalized, consisting of five recognizable segments: a clypeo-labral complex, mandibles, possible hypopharynx, a maxilla bearing indistinct palp-like appendages, and labium. Distinctive mandibles are robust, triangular, and dicondylic. The thorax is delineated into three, nonoverlapping regions of distinctive surface texture, each with legs of seven elements, the terminal-most bearing paired claws. The abdomen has ten segments deployed in register with overlapping tergites; the penultimate segment bears a paired, cercus-like structure. The anterior eight segments bear clawless leglets more diminutive than the thoracic legs in length and cross-sectional diameter, and inserted more ventrolaterally than ventrally on the abdominal sidewall.Srokalarva berthei occurred in an evolutionary developmental context likely responsible for the early macroevolutionary success of holometabolous insects. Srokalarva berthei bore head and prothoracic structures, leglet series on successive abdominal segments - in addition to comparable features on a second taxon eight million-years-younger - that indicates Hox-gene regulation of segmental and appendage patterning among earliest Holometabola. Srokalarva berthei body features suggest a caterpillar-like body plan and head structures indicating herbivory consistent with known, contemporaneous insect feeding damage on seed plants. Taxonomic resolution places Srokalarva berthei as an extinct lineage, apparently possessing features closer to neuropteroid than other holometabolous lineages.

Neuropteran insects possess very distinct larval stages with prominent paired piercing sucking stylets and a specialised sclerite, the neck, between the head and the first thoracic segment. Some larva of Crocinae (Nemopteridae) are further specialised by possessing a very elongated neck region. The fossil record has already provided a large variety of neuropteran larvae, yet so far a truly long-necked form was missing. Here we report such a fossil larva, with an elongated neck region from 100-million-year old Burmese amber. The specimen possesses a unique combination of characters unknown in any modern or fossil neuropteran larva. Besides the elongated neck it possesses three distinct teeth in the stylets, a character mostly known in larval forms of owl flies (Ascalaphidae) and ant lions (Myrmeleontidae), and a slender trunk as known in aphid lions (larvae of the groups Chrysopidae and Hemerobiidae). We must therefore conclude that the fossil species must have evolved certain characters in convergence to other lineages of Neuroptera resulting in a chimera-like morphology. We discuss possible interpretations of character evolution of larvae within Neuroptera.

Developmental biology has become a major issue for understanding the evolution of Arthropoda. While usually only the ontogenies of extant species are studied, developmental information of fossil arthropods may exhibit developmental patterns not present in living ones. Crustacea possess, basically, a more gradual development than, for example, pterygote insects and would, therefore, be appropriate candidates for the study of fossil ontogenies. Remarkably, famous fossil deposits like the Devonian Rhynie Chert or the Early Palaeozoic ‘Orsten’-type deposits do not comprise the generally macroscopic malacostracan Crustacea (although most probably adult malacostracan fossils have already been found in the Cambrian). By contrast, the Late Jurassic Solnhofen Lithographic Limestones of southern Germany provide thousands of specimens (although only few morphotypes) that can be identified as malacostracan larvae, together with juvenile specimens differing in certain morphological aspects from their conspecific adults. More recent investigations with up-to-date imaging methodology on additional malacostracan crustacean larvae yielded also reconstructible developmental sequences of species from the Solnhofen deposits. The very similar fossil deposits of the Cretaceous lithographic limestones of Lebanon have also yielded malacostracan larvae and juvenile specimens. We present a summary of the occurrences of crustacean fossils providing developmental information and a demonstration of the potential of the lithographic limestones in this context. The importance of developmental data for understanding crustacean evolution is also highlighted.

Fossil parasites represent rarities. In many cases, only trace fossils are preserved while body fossils are often lacking. We report here the first find of larval stages of parasitic isopods, identified as cryptoniscus larvae, from Chiapas Amber, Mexico (Lower Miocene). Different crustacean groups, including free-living isopods, have already been reported from the estuarine fauna presented in this type of amber. The seven specimens described here are interpreted as cryptoniscus larvae due to the following characters: 1) The general body organisation in combination with the appendage morphology. 2) A body length between 450 mu m and 695 mu m, which is known from larval stages of Bopyroidea and Cryptoniscoidea (Epicaridea). 3) The morphology of the uropods and the elongated and thin dactyli of the posterior thoracopods (pereiopods) are very similar to the condition in extant cryptoniscus larvae. Although parasitic behaviour can only rarely be directly identified in the fossil record, we can here clearly identify a specialised life stage, the cryptoniscus, which occurs only in a specific monophyletic group, of which all extant representatives are parasitic. These fossils not only represent rare cases of fossil parasites but also the first case of fossil peracarid larvae and the first body fossils of epicarid isopods.

We describe a piece of Baltic amber, about 50 million years old, which contains a group of 13 small cockroach nymphs. These specimens were documented with different methods to explore the advantages and limitations of certain imaging techniques: (1) light-based methods, such as stereo-macro photography, composite imaging under polarised light, combined with virtual surface reconstruction, and (2) X-ray micro-computed tomography, processed as volume renderings and surface reconstructions. All nymphs within the amber piece are of the same size and do not exhibit any noticeable morphological variance. Their developmental state and the way in which they are arranged indicate that these nymphs represent hatchlings. Dictyopterans (including Mantodea and Blattodea with Isoptera as ingroup) exhibit a wide range of different types of social and brood care behaviour. The evolution of this complex set of characters has been addressed repeatedly in extant-based approaches, yet deep-time aspects of this evolutionary process have rarely been addressed. The specimens described here could represent a case of a group of blattodean nymphs hatching from an ootheca, which would represent the first fossil record of such a process, or even possibly provide the first indirect evidence of social behaviour in fossil non-termite dictyopterans, indicating that it was already developed 50 million years ago.