Wednesday, 21 June 2017

Sphodromerus carapezzanus: A new species of Grasshopper from Dhofar, Oman.

The Arabian Peninsula lies between the continents of Africa and Asia, providing a bridge between the two, and the area hosts a mixture of African and Asian wildlife. The area also contains a wide range of micro-habitats, particularly where large expanses of arid desert separate isolated areas with moister climates. These isolated micro-habitats are often home to endemic species, not found anywhere else.

In a paper published in the journal ZooKeys on 8 June 2017, Bruno Massa of the Department of Agriculture at the University of Palermo describes a new species of Grasshopper from Wadi Ayun in the Dhofar Governate of Oman.

The new species is placed in the genus Sphodromerus, and given the specific name carapezzanus, in honour of Attilio Carapezza, the Italian heteropterologist (scientist that studies True Bugs, Heteroptera), who collected the specimens from which the species is described, during an expedition to the area by the Museum of Cardiff in 2016. The species is described from two specimens, one male and one female. Both are dark brown in colour with a rough surface and some lighter spots, the female being slightly larger than the male. 

Sphodromerus carapezzanus. Male (top) and female (bottom). Massa (2017).

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Monday, 19 June 2017

An Enantiornithine Bird Hatchling preserved in Cretaceous Burmese Amber.

Most Dinosaurs, including Mesozoic Birds, are known only from replacement fossils of bones, teeth, and other hard tissues, with a few rare sites such as the lithographic deposits of the Jehol or Crato biotas, or even rarer examples of Dinosaurs mummified before lithification, preserving additional details such as plumage and soft tissues. One type of deposit with potential for excellent preservation of plumage and soft tissues is amber, the preserved resin of ancient trees, which frequently preserves whole body fossils of Insects and other small animals. However Amber fragments, by their nature, tend to be very small, whereas Dinosaurs, for the most part, were extremely large, limiting the potential for the preservation of even Avian Dinosaurs in amber. To date, the known catalogue of Dinosaur specimens preserved in amber runs to a few feathers, a pair of Enantiornithine Bird wings and the tip of the tail of a small non-Avian Coelurosaurian Theropod.

In a paper published in the journal Gondwana Research on 6 June 2017, Lida Xing of the State Key Laboratory of Biogeology and Environmental Geology and School of the Earth Sciences and Resources at the China University of Geosciences, Jingmai O'Connor of the Key Laboratory of Vertebrate Evolution and Human Origins at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, Ryan McKellar of the Royal Saskatchewan Museum, the Biology Department at the University of Regina, and the Department of Ecology & Evolutionary Biology at the University of Kansas, Luis Chiappe of the Dinosaur Institute at the Natural History Museum of Los Angeles County, Kuowei Tseng of the Department of Exercise and Health Science at the University of Taipei, Gang Li of the Institute of High Energy Physics of the Chinese Academy of Science, and Ming Bai of the Key Laboratory of Zoological Systematics and Evolution of the Institute of Zoology of the Chinese Academy of Sciences, describe a preserved Hatchling Enantiornithine Bird from a piece of amber from the Angbamo site at Tanai Township in Myitkyina District of Kachin Province in northern Myanmar.

Middle Cretaceous ‘Burmese Amber’ has been extensively worked at several sites across northern Myanmar (though mostly in Kachin State) in the last 20 years. The amber is fairly clear, and often found in large chunks, providing an exceptional window into the Middle Cretaceous Insect fauna. This amber is thought to have started out as the resin of a Coniferous Tree, possibly a Cypress or an Araucaria, growing in a moist tropical forest. This amber has been dated to between 105 and 95 million years old, based upon pollen inclusions, and to about 98.8 million years by uranium/lead dating of ash inclusions in the amber. 

The preserved Hatchling is not intact, having apparently only partly covered by resin initially, with part of the body therefore left exposed to the actions of the elements, and scavengers, and hence lost; the whole subsequently covered by additional layers of resin, and eventually preserved as amber. The remains are preserved in a block of amber approximately 86 mm x 30 mm x 57 mm and weighing 78.16 g. This block has been split into two sections during preservation; this split having unfortunately passed through part of the jaw, causing some loss of material. The remains comprise the head and most of the neck of the Bird, as well as a partial wing and the feet, and some additional plumage and soft tissue.

Overview of specimen in right lateral view. (A) Amber specimen; (B) x-ray μCT reconstruction; (C) illustration of observable plumage and skin sections. Two halves of amber piece have been positioned side by side (A) or separated by dashed line (C), and body regions scanned separately have been arranged in preservational position (B). For clarity in (C), only rachises of apical remiges indicated; and only rachises and rami of basal remiges, coverts, contours, and neoptile plumage indicated. Scale bars represent 10 mm. Xing et al. (2017).

The Bird appears to have two basic types of plumage, soft down feathers similar to those seen in modern Bird chicks, combined with longer fibrous feathers similar to those seen in many Dinosaurs, as well as some developed flight feathers on the wing. The skeleton is consistent with that of other preserved early-development Enantiornithine chicks, lending confidence to the diagnosis of this bird as an Enantiornithine. The developmental strategy in this Bird appears to have been different to that in modern Birds, in that it was apparently both arboreal (tree-dwelling) and precocial (able to move about immediately upon hatching). Modern Birds almost invariably follow one of two strategies; with tree-nesting species tending to need a period of care before leaving the nest (though many species do leave the nest before they can fly) and ground-nesting Birds producing precocial offspring that become active almost immediately.

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Sunday, 18 June 2017

Understanding the integument of Tyrannosaurid Dinosaurs.

Many recent discoveries of Theropod Dinosaurs have revealed traces of feather coverings, leading to speculation that all members of this group may have been feathered. The discovery of the feathered Tyrannosaurids, Dilong paradoxus and Yutyrannus huali, from the Early Cretaceous of China, has extended this speculation to the very largest Tyrannosaurid Dinosaurs, particularly as Yutyrannus itself was a large Tyrannosaurid (about nine meters) with an extensive feather coat, raising the possibility that the largest known Therapod Dinosaur, Tyrannosaurus rex, might have had feathers.

In a paper published in the journal Biology Letters on 7 June 2017, Phill Bell of the University of New England, Nicolás Campione of the Palaeobiology Programme at Uppsala University, Scott Persons and Philip Currie of the University of Alberta, Peter Larson of the Black Hills Institute of Geological Research, Darren Tanke of the Royal Tyrrell Museum of Palaeontology and Robert Bakker of the Houston Museum of Natural Science, describe the results of a study of skin traces from Tyrannosaurus rex and several other large Tyrannosaurids, and draw conclusions about the evolution of skin covering of Tyrannosaurid Dinosaurs from this study.

Bell et al. examined a number of skin traces associated with a Tyrannosaurus specimen collected from the Hell Creek Formation near Baker in Montana (specimen HMNS 2006.1743.01, sometimes known as ‘Wyrex’). This specimen has numerous skin patches from different parts of its body, none of which show any trace of feathers, leading Bell et al. to conclude it was featherless. The scales of HMNS 2006.1743.01 are small in size and highly variable in shape, with no larger feature scales (known from other Dinosaur species) and no scales showing polarity (i.e. having a distinct anterior-posterior axis, presumably the first step in developing towards a feather-like form). Interestingly, in several places where large patches of skin are preserved, these scales show signs of being arranged into a leaf-like pattern, with scales arranged into trapezoidal or triangular clusters, separated by bands of incised interstitial skin, which follow a branching arrangement similar to the midrib and lateral veins on a plant leaf. 

Integument of Tyrannosaurus rex (HMNS 2006.1743.01). (a) Proximal caudal vertebrae 6–8 in right lateral view. Integument from the neck (b,c), the ilium (d,e) and caudal vertebrae (f–h). Green lines indicate ‘vein and midrib’ patterns. Scale in (a) is 10 cm; (b)–(e) are 5 mm and (f)–(h) are 10 mm. Bell et al. (2017).

Next Bell et al. examined preserved skin specimens from four other large, Late Cretaceous Tyrannosaurs, Daspletosaurus, Tarbosaurus, Albertosaurus, and Gorgosaurus. Unlike the Early Cretaceous Chinese specimens, none of these Late Cretaceous North American and Mongolian Tyrannosaurs show any signs of feathers. 

The distribution of feathers among Theropod Dinosaurs suggests that at least primitive feathers (i.e. hollow tubes) were present in the earliest Coelurosaurs, the group to which the Tyrannosaurs belong, with more advanced features such as rachis, barbs and barbules and eventually fully formed flight feathers appearing sequentially within Maniraptoran Theropods and eventually Birds. Some Ornithischian Dinosaurs also had primitive feathers, suggesting that either simple feathers appeared before the two groups diverged, or that they evolved separately in the two groups. No trace of feathers or feather-like structures has ever been found in any Sauropod Dinosaur. 

Like other Coelurosaurs, the earliest Tyrannosaurs appear to have had a full coat of simple, fibrous feathers, and as in other non-avian Theropods, no Tyrannosaur has been found with evidence of a partial-feather covering. Indeed, the earliest Birds, such as Archaeopteryx, appear to have been completely covered in feathers, with the scaly feet and legs of modern Birds apparently secondarily derived. This strongly suggests that the scaly skin of later Tyrannosaurs is also secondarily derived from a feathery covering. 

The earliest Tyrannosaurs were relatively small animals, with gigantism achieved twice within the group, once rapidly, in the Early Cretaceous lineage that led to Yutyrannus, and once more gradually over the course of the Cretaceous in the lineage that culminated in Daspletosaurus, Tarbosaurus, Albertosaurus, Gorgosaurus and Tyrannosaurus. This is important, as it shows that Yutyrannus is not the ancestor of the Late Cretaceous giant Tyrannosaurs, and that it therefore presumably evolved under different ecological and evolutionary pressures to these animals, and that understanding these pressures may be the key to understanding the distribution of feathers among Tyrannosaurids. 

Some earlier studies have suggested that temperatures in Early Cretaceous western Liaoning (where Dilong paradoxus and Yutyrannus huali lived) may have been significantly cooler than the North American and Mongolian environments that produced the Late Cretaceous giant Tyrannosaurs, leading these Early Cretaceous forms to need an insulating feather coat that the Late Cretaceous forms lacked. However recent palaeoenvironmental studies have not supported this, implying a similar temperature range. One difference that may be important is tree-cover, with the Liaoning deposits thought to have been laid down in a dense forest environment, while the later Cretaceous Tyrannosaurids are believed to have inhabited more open environments. This reflects the case in modern Asian Elephants and Javan Rhinoceroses, which are live in dense forest environments and are hairier than their African relatives that live on open Savanah. While all of these animals live in hot climates, and are more concerned with losing excess heat that keeping warm (always more of a problem for large animals anyway), the Asian forms, which live beneath the shade of large trees, are apparently subject to less heat-stress than the African forms. 

However the Late Cretaceous Tyrannosaurids are known to have lived alongside feathered Dinosaurs, with Albertosaurus in particular having been found alongside feathered Ornithomimids. Bell et al. suggest that the feather-loss in Tyrannosaurids compared to Maniraptorans (such as the Ornithomimids) may be related to a more active lifestyle, i.e. expending more energy and therefore generating more body-heat. Tyrannosaurs had relatively longer legs than other large Theropods, and arctometatarsalian feet (expand), which has been interpreted as being indicative of a more active lifestyle, possibly even engaging in bouts of rapid or lengthy pursuit (generally the only ways for a large predator in an open environment to catch prey, since opportunities for ambush are relatively limited). 

Finally, the Late Cretaceous Tyrannosaurs grew considerably larger than the Early Cretaceous forms, with only the smallest, Albertosaurus, at an estimated 1325–2210 kg is thought to be comparable in size to Yutyrannus, at about 1414 kg, while the other species were much larger; Tarbosaurus at 1744–2945 kg, Gorgosaurus at 2145–3577 kg, and Tyrannosaurus at 5014–8361 kg, suggesting that these species would have been subject to more heat-stress. 

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The 2017 June Solstice.

The June (or Northern) Solstice falls on Wednesday 21 June in 2017, the day on which the Sun rises highest in the sky and the longest day of the year in the Northern Hemisphere (where it is the Summer Solstice) and the day on which the Sun rises lowest in the sky and the shortest day in the Southern Hemisphere (where it is the Winter Solstice). Up until this date the days have been growing longer in the Northern Hemisphere and shorter in the Southern Hemisphere since the December Solstice (which is the Winter Solstice in the Northern Hemisphere and Summer Solstice in the Southern Hemisphere), but after it the situation will be reversed, with days growing steadily shorter in the Northern Hemisphere and longer in the Southern Hemisphere until the next December Solstice.

The solstices are entirely a product of variation in the Earth's rotation on its axis, which is at an angle of 23.5° to the plain of the Earth's orbit about the Sun. This means that in December the Earth's Southern Pole is tilted towards the Sun, while the Northern Pole is tilted away from it. This means that around the Southern Solstice the Southern Hemisphere is receiving radiation from the Sun over a longer part of the than the Northern, and at a steeper angle (so that it to pass through less atmosphere to reach the planet), creating the southern summer and northern winter.

 The tilt of the Earth at the Northern Solstice. Wikimedia Commons.

The solstices are fairly noticeable astronomical events, and tied to the seasons which govern the life cycles of life on Earth, and they have been celebrated under different names by cultures across the globe, but most notably by those at higher latitudes, who are more profoundly affected by the changes of the seasons.

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Wednesday, 14 June 2017

Megalosaurus bucklandii: Understanding the history and conservation of a 200-year-old museum specimen.

Museums provide a repository for many millions of cultural artifacts and natural specimens, and are responsible for their conservation and preservation. In order to do this efficiently a record of any repairs or other work carried out on these objects should be kept, however in the case of many older specimens these records may have been lost or destroyed, or may never have been made in the first place, presenting a challenge to museum curators. Megalosaurus bucklandii was the first Dinosaur species to be formally described (excluding living Birds), by Gideon Mantell in 1827. The species was described from a number of bone fragments recovered from the Stonesfield Limestone Quarry in Oxfordshire, England, from the seventeenth century onwards. One of these fragments has subsequently been designate the lectotype for the species (modern taxonomists designate a specimen as the holotype when describing a species, any further specimens adjudged to belong to the same species as the holotype are therefore the same species; however if this holotype is lost, or no holotype was designated, usually the case with eighteenth and nineteenth century specimens, then a lectotype can be designated with the same status), a fragment of jaw obtained by Christopher Pegge of Oxford University from a quarryman in 1797. This specimen is known to have undergone repairs at some point, with parts of the specimen replaced with some form of plaster, though no record of this work is known.

In a paper presented at the IEEE International Instrumentation and Measurement Technology Conference in Torino, Italy on 22-25 May 2017, and due to be published in the proceedings of that conference,  and published on the Warwick Research Archive Portal at the University of Warwick on 17 February 2017, Paul Wilson, Mark Williams, Jason Warnett and Alex Attridge of the Warwick Manufacturing Group at the University of Warwick, and Hilary Ketchum, Juliet Hay, and Paul Smith of the Oxford University Museum of Natural History at the University of Oxford, describe the results of a study of the lectotype of Megalosaurus bucklandii, made using a Nikon (Xtek) XT H 320LC μCT scanner at the Institute of Imaging, Metrology and Additive Technology at the University of Warwick 

 The Megalosaurus bucklandii dentary with 3D Printed Replica. (a) Photograph of the lectotype right dentary of Megalosaurus bucklandii. (b) 3D print of the lectotype dentary in a photopolymeric resin. Scale bars represent 50mm.Wilson et al. (2017).

Wilson et al. found that repair to the specimen was less extensive than had previously been thought. Two distinct materials, both thought to be forms of plaster, have been used in repair, identified as Material 1 and 2 (or M1 and M2). The first material (M1) has a distinctly lower density that the material of the specimen, but with a scattering of higher density particles throughout, and has been used on the posterior and ventral part of the jaw. The second material (M2), lacks the higher density particles and has mainly been used on the teeth.

XCT diagnosis of zones of repair and materials. (a) Medial surface of the dentary. (b) Lateral surface of the dentary. Red zones represent those of Material 1 (M1) and Green zones those of Material 2 (M2). Wilson et al. (2017).

As well as demonstrating the extent of repairs to the jaw, Wilson et al. have created a three dimensional digital model of the specimen which can potentially be used by future researchers even if it is lost or further degraded or damaged in future. They note that the methodology has the potential to be used on many other older museum specimens, and also that similar technology was used in the uncovering of the 'Archaeoraptor liaoningensis' Dino-bird hoax in 2000, and recommend that the methodology be more widely used on museum specimens.

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Tuesday, 13 June 2017

Boalda poguei: A new species of Owlet Moth from Paraguay,

Owlet Moths, Noctuidae, are an extremely large and diverse group of Moths, found on every continent and significant landmass except Antarctica. The adults are mostly small and dull, though some are brightly coloured, with many species being important pollinators. The larvae can be herbivores or carnivores, with many species considered to be significant agricultural pests.

In a paper published in the journal Zootaxa on 9 June 2017, Paul Goldstein of the Systematic Entomology Laboratory at the Smithsonian National Museum of Natural History describes a new species of Owlet Moth from Paraguay, as part of a review of Moths of the genus Boalda.

The new species is named Boalda poguei, in honour of Michael Pogue, one of the collectors of the specimens from which the species is described. The species is described from three male specimens, all collected in the Parque Nacional Teniente Enciso in Boquerón Department, Paraguay. These are small, with a forewing length of 8 mm, and russet in colour with pink and white markings.

Boalda poguei, male specimen in dorsal view. Goldstein (2017).

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Monday, 12 June 2017

Five new species of Broad-nosed Weevil from Dominican Amber.

Weevils, Curculionidae, are one of the largest and most diverse groups of Beetles. They first appeared in the Early Cretaceous, becoming common and diverse by the end of that period. Broad-nosed Weevils, Entiminae, first appear in Early Eocene Fushan Amber from China. They have larvae which infest the roots of plants, a novel innovation on this group, which has allowed them to exploit a range of new environments, enabling them to diversify rapidly and spread widely during the Eocene.

In a paper published in the journal Paleontologica Electronica in May 2017, George Poinar of the Department of Integrative Biology at Oregon State University and Andrei Legalov of the Institute of Systematics and Ecology of Animals of the Siberian Branch of the Russian Academy of Sciences describe five new species of Entimine Weevil from amber mines in the northern part of the Dominican Republic.

Amber from the Dominican Republic is generally thought to be 15-20 million years old (i.e. Miocene in age), and is obtained from mines in the Cordillera Septentrional mountain range, where it is found as inclusions in turbiditic sandstones (marine landslip deposits). This secondary deposition makes it possible that the Amber is much older than the deposits in which it is found, possibly as old as 40 million years (Early Eocene). It was produced by a Leguminous tree, Hymenaea protera, which, based upon the ecology of the organisms found in the amber, is interpreted as having lived in moist tropical forests.

The first new species described is placed in the genus Diaprepes, which is still found in the Caribbean today, and given the specific name squamula, meaning scaly, in reference to the dense scaly covering of the Weevil. The species is described from a single specimen, 9.0 mm in length with a 0.6 mm snout, black in colour, with a dense covering of light, rounded scales. 

Ventral view of Diaprepes squamula, In Dominican amber. Scale bar is 1.0 mm. Poinar & Legalov (2017).

The second species described is placed in the genus Lachnopus, also still found in the Caribbean today, and given the specific name serraticrus, meaning ‘toothed-leg’, in reference to a pattern of prominent serrations on the Insect’s tibia. This species is also described from a single specimen, 7.4 mm in length with a 1.4 mm snout, black in colour with small, subcircular scales.

Lateral view of Lachnopus serraticrus in Dominican amber. Scale bar is 1.3 mm. Poinar & Legalov (2017). 

The third new species described is placed in the genus Apodrosus, another modern Caribbean genus, and given the specific name tinctocorpus, meaning ‘dyed body’ in reference to the colour of the body, which brown-black and lacks any markings. The species is described from a single specimen, 5.0 mm in length with a 0.8 mm snout, and small oval scales.

Lateral view of Apodrosus tinctocorpus in Dominican amber. Scale bar is 1.2 mm. Poinar & Legalov (2017).

The fourth new species is also placed in the genus Apodrosus, and given the specific name canalinasus, meaning ‘grooved-nose’ in reference to a distinctive furrow on the snout. The species is described from a single specimen, 4.5 mm in length, with a 0.8 mm snout, and covered in small oval scales.

Lateral view of Apodrosus canalinasus in Dominican amber. Scale bar is 0.8 mm. Poinar & Legalov (2017). 

The fifth new species described is placed in the genus Promecops, today found in the Caribbean, as well as in Central and South America, and given the specific name divarichela, meaning ‘spread-apart claws’, in reference to the free tarsal claws. The species is described from a single specimen 3.1 mm in length with a 0.4 mm snout, brown-black on colour and with curved, narrow scales.

Lateral view of Promecops divarichela in Dominican amber. Scale bar is 0.7 mm. Poinar & Legalov (2017).

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