ELMO FOSSIL INSECTS IN BRIEF:
The image to the right was scanned by Roy Beckemeyer from an Elmo fossil in the possession of Dr. George Byers, Emeritus Professor of Entomology from Kansas University. It is a protorthopteran of the Family Lemmatophoridae, likely Lemmatophora typa Sellards 1909. Not catalogued, the fossil is in a small collection of that Dr. Byers uses in teaching entomology classes. Scanned in October, 1999 at the Snow Entomological Museum, Lawrence, Kansas. Thanks to Dr. Byers for allowing me access to his fossils. See the discussion below for additional pictures including drawings depicting how paleontologists think that this and other fossil insects might have looked.
IN THIS SECTION I briefly describe each insect order found in the Elmo fauna, and provide a link to a picture of a representative insect if such a picture exists. Many insect fossils consist only of wings or wing fragments. This is because wings are basically cuticle, so they are generally not eaten by predators, and do not deteriorate as quickly as other portions of the body which contain muscle and other tissues. Thus many of the insects from the Elmo deposit are known only by their wings. Some, however, are found in such numbers at the site that body parts have been found preserved as well.
When enough body fragments are available, the paleontologist studying the insect may be able to do a reconstruction or restoration drawing depicting what the insect likely looked like. For those taxa, we include here habitus drawings. I have adapted these drawings by scanning them in, and providing a scale of reference: a line, usually 5mm or 1 cm long to give an indication of their size. The thumbnail pictures may be clicked if you wish to see an enlarged image. Click the "back" button on your web browser to return to the list.
Eventually the Checklist of Elmo Permian Insects will contain links to pictures or photos of wing venation or other features of each species. I have therefore restricted this page to habitus drawings of representative taxa.
APTERYGOTA (Primitively wingless insects):
ORDER ARCHAEOGNATHA: The bristletails are primitive wingless insects with a long "caudal process" or tail, but without cerci. The thoracic segments look very much like the abdominal segments dorsally. The single species described from Elmo is Lepidodasypus sharovi Durden 1978 (Family Dasyleptidae). The thumbnail depicts a drawing of the fossil from Durden's description.
PTERYGOTA (Winged insects): PALAEOPTERA (Insects that could not fold their wings down flat against the dorsum of their abdomen):
ORDER EPHEMEROPTERA: The only palaeopterous order that has existed from the Upper Carboniferous to the present, the order Ephemeroptera comprises the mayflies. The order is referred to in the works of Sellards, Tillyard, and Carpenter by the name Plectoptera. Today's mayflies do not have functional mouths as adults, and live only a day or so, dying soon after mating. Fossil mayflies had chewing mouthparts as adults. Another difference between fossil and modern species of mayflies is in the wings. In modern forms, the hind wing is very much reduced in size, and in some cases is absent. In fossil forms, the fore and hind wings are approximately the same size. Mayfly adults have three long filamentous abdominal appendages. The thumbnails depict two fossil species. The one on the left is a scanned image of a photograph of a fossil of Misthodotes obtusus Sellards 1907 (Family Misthodotidae). The two drawings on the right are of Protereisma permiana Sellards 1907 (Family Protereismatidae). The small thumbnail is Tillyard's restoration of the insect, and the larger one is Carpenter's. The insects in life held their wings together over their back as shown in Tillyard's depiction. As in the other habitus drawings, the wings are shown in Carpenter's drawing as they would appear if the insect were pinned for display (this is done so the venation, which is mainly how the fossil insects are classified, is visible).
ORDER PALAEODICTYOPTERA: These insects had sucking mouthparts and held their wings open much like today's dragonflies. Some of the taxa had remarkably patterned wings, and those patterns are sometimes preserved quite nicely in the fossil record. One of the most spectacular is the insect featured widely in this web site, Family Spilaapteridae: Dunbaria fasciipennis Tillyard 1924. The palaeodictyopterids also had winglets on their prothorax - a feature shared by the similar orders Megasecoptera and Diaphanopterodea. Modern insects and those of most other fossil orders have wings only on their meso- and meta-thoraces, though they have legs on each segment. It is thought that these insects fed on plant juices or on the semi-liquid endosperm of Paleozoic plants.
ORDER MEGASECOPTERA: A group that is very similar to the previous order, with sucking mouthparts, but with wings nearly equal in size, and that are noticeably long and slender (often with very slender wing bases reminiscent of the shape of the wings of modern damselflies). They held their wings out horizontally like today's dragonflies. Shear and Kukalova-Peck (1990) said of these insects: "Predation on Paleoptera with sucking beaks must have been extremely high because of their size, body form, and feeding habits. Since they comprised about 50% of the entire entomo-fauna, their impact on the development of plant fructifications and the evolution of both insect and vertebrate predators is probably highly significant and should be accounted for in evolutionary models." The thumbnails depict reconstructions of Carpenter (left, Protohymen readi Carpenter 1933) and of Kukalova-Peck (right, a "generic" Protohymen based on features of P. readi and P. permianus).
ORDER DIAPHANOPTERODEA: This group of Palaeoptera with sucking mouthparts is quite similar to the previous order, but differs in that its members can fold their wings back along their abdomens. Kukalova-Peck (1974) studied the wing-base sclerites of this and the previous two orders (sometimes grouped together as "palaeodictyopteroids"); the folding mechanism of the Diaphonopterodea differed from that of the Neoptera having evolved independently, but it did allow very similar folding of the wings. The thumbnail depicts Asthenohymen dunbari Tillyard 1924. Wooton (1981) commented that "...the convergence between the small Asthenohymenidae and the megasecopterous Protohymenidae is remarkable. Asthenohymenidae include the smallest palaeodictyopteroids, their span may be as little as 9 mm."
ORDER PROTODONATA: These dragonfly-antecedents were generally large and occasionally gigantic in size. The largest insect known was a protodonate from the Kansas Elmo Lagerstatten: Family Meganeuridae: Meganeuropsis permiana Carpenter 1939. It had a wing that was estimated to be 330 mm long. That would yield a wingspan of nearly 29 inches, and a body that was at the limit of size for which tracheal ventilation could provide sufficient oxygen to the thoracic muscles to sustain flight. They also very likely had the ability, as do a number of modern insects, to actively control their thoracic temperature (May, 1982), thus making them the first flying endotherms. Shear and Kukalova-Peck (1990) called them "...the top aerial predators of the Paleozoic", and noted that they "...were very abundant and diverse in the Carboniferous and Permian, but may have been preferentially preserved since, like modern forms, they frequented swamps, lakes and pond margins." The thumbnail on the upper right is a photo of part of a poster that depicts giant protodonate wings from Kansas and Oklahoma at full size and in scale. The one on the upper left might be titled "Permian Park", and is a humorous bookplate drawn by a famous dragonfly student, Dr. Clarence H. Kennedy. It shows a family camped on a tropical beach, and a young man coming out of the jungle holding a giant dragonfly by the tail. The species used, Meganeura monyi, is a protodonate from the Upper Carboniferous of France that had a wing length of 310 mm, giving it a wingspan just a couple of inches shorter than that of our Meganeuropsis permiana. Dr. Kennedy appears to have anticipated the movie Jurassic Park (the drawing was probably done 60 or 70 years ago)! The photo on the right above shows Werner Kraus, geological and paleontological preparator at Aachen University, with a life-size model of Meganeuropsis permiana that he prepared while working with Dr. Carsten Brauckmann, a specialist in Protodonata at the Technische Universitaet Clausthal in Germany.
ORDER ODONATA: Dragonflies and damselflies quite similar to those that fly today were present in the Elmo fauna. Like the Protodonata, the Odonata are predaceous and palaeopterous - they cannot fold their wings down flat against the dorsum of their abdomens. It is possible that their generally smaller size was advantageous to their continued survival to modern times. The idea has been advanced that increased atmospheric oxygen during the Carboniferous and Permian (Graham et al, 1995) allowed the evolution of very large flying insects, and that the decrease in atmospheric oxygen level at the end of the Permian contributed to the extinction of the Protodonata and other large insects. In any event, the Odonata and Protodonata very likely flew and fed in similar fashion, but preyed on different size classes of insects.
PTERYGOTA (Winged insects): NEOPTERA (Insects capable of folding their wings down flat against the dorsum of their abdomens): EXOPTERYGOTA (Insects that undergo incomplete metamorphosis):
ORDER PROTORTHOPTERA: The Order Protorthoptera includes a fairly diverse assemblage of orthopteroid insects. The group is likely polyphletic as it has been described by Carpenter. Insects classified into this order dominated Palaeozoic faunas. There are 34 species recognized from Elmo, half again as many as in the next largest order (Psocoptera at 22 species). Many of the Elmo species are plecopteroid in appearance, bearing obvious relationships to the Plecoptera (stoneflies). In most cases only the fore wings have been preserved, so classification and differentiation of taxa has proven to be difficult in this group. But, because of the abundance of protorthopteran specimens in the collections of Yale and Harvard, there are fairly complete fossils available, and more restorations of complete insects have been done for this group than for any of the others. Insects in this group have chewing mouthparts and often have fore wings that are somewhat hardened. Their wings were folded down flat against the dorsum of their abdomens (they were Neoptera), although they are depicted in these habitus drawings with wings extended. Thumbnails are provided here for eight species in all: Family Chelopteridae: Chelopterum peregrinum Carpenter 1950; Family Lemmatophoridae: Lemmatophora typa Sellards 1909, Paraprisca fragilis (Sellards) 1909, Lecorium elongatum Sellards 1909, and Liomopterum ornatum Sellards 1909; Family Probnidae: Probnis speciosa Sellards 1909; Family Proterembiidae: Proterembia permiana Tillyard 1937; and Family Tococladidae: Opisthocladius arcuatus Carpenter 1976.
ORDER BLATTARIA: Carpenter (1992) did not address the cockroaches in his Treatise volumes on fossil insects. The highly variable wings of these insects make classification difficult, and a long-range study of this order has been underway for many years by Dr. Jorg Schneider of Freiberg, Germany. I have thus listed in the checklist the Elmo taxa as they were defined by Tillyard. This was one of the largest orders of insects during the late Paleozoic, and the forms of cockroaches living then were very much like modern ones.
ORDER PROTELYTROPTERA: (The thumbnail depicts the following taxon: Family Protelytridae: Protelytron permianum Tillyard 1931). This order was established by Robin J. Tillyard in 1931 on the basis of the Elmo specimens. This is a group of small insects that are related to cockroaches, and are ancestral to modern earwigs (Order Dermaptera). They have conspicuous eyes and fairly long antennae. Their front wings, called elytra, are actually hardened covers for the hind wings. The first specimens of this order found at Elmo were actually thought briefly to be related to beetles (Coleoptera) because of the elytra; Shear & Kukalova-Peck (1990) remarked that "They are remarkably convergent to beetles". In fact, it may be impossible to distinguish these insects from early beetles if the hind wings are not available. This order is exclusive to the Permian. Specimens from this group are also found in large numbers in Moravia, Australia, and South Africa. Nine genera and 15 species are known from Elmo.
ORDER ORTHOPTERA: Carpenter chose to place in this order only the saltatorial or leaping insects, that is, the ones like our modern grasshoppers. As the grasshoppers have evolved, their fore wings have become quite heavy and have come to serve as covers for the folded wings, and stridulatory organs have developed on the fore wings of the males.
ORDER PSOCOPTERA: (The thumbnails depict two different species from Family Psocidiidae: Dichentomum tinctum (Tillyard) 1926 and D. kansasense (Tillyard) 1926. (Both species were originally described in the genus Psocidium. Psocids are still found today, and are commonly referred to as "book lice" or "bark lice". These are diminutive insects with large heads and prominent eyes. Psocids are thought to be most closely realted to the Hemiptera, but they have chewing mouth parts rather than the sucking beaks of the Hemiptera. (Note, though, that the Dichentomum have a beak-like extension of the front of the head.) The Permian Pscocoptera have homonomous wings, that is, the front and hind wings are identical in size and venation.
ORDER CALONEURODEA: This order is considered to be related to the Protorthoptera. However, where the Protorthoptera have different fore and hind wings, the wings of Caloneurodea are similar in venation, texture, and shape. The insects had chewing mouthparts and long, slender antennae.
ORDER MIOMOPTERA: Small to very small insects with biting mouthparts, short cerci, and nearly identical fore and hind wings. Little is known of the bodies of species of this order.
ORDER HEMIPTERA: The Elmo Permian Hemiptera (Suborder Homoptera) were mostly small. Like today's Homoptera (cicadas, plant hoppers, etc.), the Permian forms had sucking mouthparts.
PTERYGOTA (Winged insects): NEOPTERA (Insects capable of folding their wings down flat against the dorsum of their abdomens): ENDOPTERYGOTA (Insects that undergo complete metamorphosis):
ORDER GLOSSELYTRODEA: Even though the body structure of this order is very poorly known, these small insects are considered by Carpenter to be Endopterygota. This is because the wings have traits which are found in the Endopterygote Order Neuroptera (Tillyard, 1932, originally placed Permoberotha villosa in the order Neuroptera): rows of setae on the wing veins, cross veins, and wing margins, and the position of the wings at rest.
ORDER MECOPTERA: Small to medium-sized insects that are characterized by a long, beak-like face. They have chewing mouth parts and modern forms are predacious or eat dead insects. Modern Mecoptera are often found in wooded areas. The popular name, "scorpion flies", has its origin in the upturned genitalia of males of the extant family Panorpidae, which resemble the tails of scorpions. Two of the thumbnails depict the fossil species Permopanorpa inaequalis Tillyard 1926. One is a scanned image of a photo used in Carpenter's 1930 treatment of the order, and the other a drawing of the insect. The third thumbnail is a modern scorpion fly that is found in Kansas (though only in Cherokee County in the extreme southeastern part of the state), Panorpa nuptialis, as depicted on a recent postage stamp.
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