Friday, 22 February 2019

Eruptions from new fissure on Piton de la Fournaise.

The Observatoire Volcanologique du Piton de la Fournaise reported sharp increase in seismic activity beneath Piton de la Fournaise, a shield volcano which forms much of the eastern part of Réunion Island, an island in the western Indian Ocean which forms a department of France, starting slightly after 3.20 pm on Saturday 16 February 2019, and persisting for slightly over an hour. This resumed slightly after 9.15 am on Monday 18 February, and was accompanied by rapid deformation on the eastern flank of the volcano, and eventually the opening of a fissure on that flank from which a lava fountain emerged, reaching heights of about 30 m, and resulting in a lava flow that reached about 1900 m down the flank of the volcano. This continued until about 10.00 pm. Further earthquakes and gas emissions were recorded on 19 February, and on the 20th an overflight by vulcanologists from the Observatoire Volcanologique du Piton de la Fournaise recorded another fissure on the eastern flank.

A lava flow on the eastern flank of Piton de la Fournaise on 20 February 2019. Le Chaundron de Vulcan.

Piton de la Fournaise is believed to have been active for about 530 000 years, though its geology is complicated to unravel as lava flows are interbedded with those from Piton des Neiges, a larger, older and now extinct volcano to the northwest, which is responsible for the formation of about two thirds of the island. The island sits on the Réunion Hotspot, a deep mantle plume which is thought to have been active for about 66 million years, originally forming under what is now northeastern India, where it was responsible for the Deccan Traps flood basalts, then moving southward across the Indian Ocean (or more precisely sitting still while the continental plate upon which India and the Indian Ocean sit moves to the north), over time forming the Laccadive Islands, the Maldives, the Seychelles, Rodrigues Island, Mauritius and Réunion.

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Magnitude 4.6 Earthquake in northeastern Libya.

The Centre Seismologique Euro-Méditeranéen  recorded a Magnitude 4.6 Earthquake at a depth of 10 km about 3 km to the west of the city of Al Bayḑā on the northeast coast of Algeria, slightly before 3.20 am local time (slightly before 2.20 am GMT) on Thursday 21 February 2019. There are no reports of any damage or casualties associated with this event, though it may have been felt locally.

 The approximate location of the 11 February 2019 ’Aïn el Turk Earthquake. EMSC.

Libya lies on the northernmost part of the African Plate, while southern Europe to the north is part of Eurasia. Africa is pushing into Europe from the south, which causes Earthquakes around the Mediterranean Basin. These are most common in southeast Europe, but those in North Africa, while less frequent, are often larger and more deadly.

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organisation Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.

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Wednesday, 20 February 2019

Aloe sanguinalis: A new species of Aloe from Somaliland.

Aloes, Aloe spp., are large, thorny succulent plants found in Africa, Arabia, and the islands of the western Indian Ocean, where they fill roughly the same ecological niche as Cacti. Aloes are Monocotyledons, with fleshy, blade-shaped leaves with thorns along their edged, arranged into spiral rosettes. Many Aloes are stemless shrubs, others have horizontal or upright stems, the later often being known as Tree Aloes.

In a paper published in the journal PhytoKeys on 8 February 2019, Mary Barkworth of the Biodiversity Museum at the University of Hargeisa, and the Biology Department at Utah State University, Ahmed Ibrahim Awale, also of the Biodiversity Museum at the University of Hargeisa, and of Candlelight for Environment, Education, and Health, and the College of Applied and Natural Science at the University of Hargeisa, and Faisal Jama Gelle, again of the Biodiversity Museum at the University of Hargeisa, describe a new species of Aloe from Somaliland.

Somaliland was a province of Somalia until 1991, when it unilaterally declared independence from Somalia at the outbreak of the Somalian Civil War. Few outside countries recognised this independence, but it did serve to protect Somaliland against much of the chaos that enveloped the rest of Somalia, and enabled, amongst other things, a degree of botanical exploration to go on in the area, with several new species of Aloe being described from the territory while war raged to the south.

The new species is named Aloe sanguinalis, meaning ‘blood’ in reference to the sap of the species, which is yellow when it emerges, then turns red, then dries to a deep red. It forms large clumps of plants, with leaves of a uniform green with red thorns, and produces widely spaced red flowers on tall flower spikes.

Aloe sanguinalis at Alala Adka showing the largest clump in October 2016. Barkworth et al. (2019).

Aloe sanguinalis appears to have few natural enemies; the areas where it was growing were heavily grazed by Goats and Cattle, both of which ignored the Aloe, despite other plants in the area apparently being overgrazed. The Catholic missionary Evangelist de Larajasse, who was based in Berbera between 1888 and 1893, reported seeing a species of red Aloe that was fed upon by Elephants, which may have referred to Aloe sanguinalis, but Elephants have not been seen in Somaliland since 1958, so these are not an obvious threat. Some marks were found on the leaves which may have come from piercing Insects, though this damage was limited.

Ahmed Ibrahim Awale with a clump of Aloe sanguinalis at Lafarug in January 2018. Barkworth et al. (2019).

Aloe sanguinalis was found growing at two separate locations, alongside a road near Alala Adka in the Marodi Jeh Region, and alongside the road to Hiin-Weyne village, near Lafarug in the Sarhil Region. The species forms notably large clumps, with the largest encountered being about forty metres by ten, and containing about 2500 individual stems; it what not clear to what extent these represented individual plants rather than offshoots of established plants. Despite the apparent lack of predators the species is not without threats, with the increasing frequency of drought in the region being of particular concern; no immature plants were observed in the field, which may indicate that new plants were not being established.

Inflorescence of Aloe sanguinalis at Lafarug, June 2018. Barkworth et al. (2019). 

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Tuesday, 19 February 2019

Malawisaurus dixeyi: The braincase and inner ear of a Southern African Titanosaur.

Titanosaurs were a group if exceptionally large Sauropod Dinosaurs that dominated many faunas in the Southern Hemisphere during the Cretaceous. The group includes the largest known Dinosaurs, with species such as Argentinosaurus and Puertasaurus thought to have weighed close to 90 tonnes. However the group was quite diverse, and also contained many smaller species, as well as both long and short-necked forms, suggesting a wide range of ecological specialisations.

Titanosaur remains from Malawi, Southern Africa, were first described under the name Gigantosaurus dixeyi in 1928. These fossils underwent several name-changes as our understanding of Dinosaur taxonomy changed and grew during the twentieth century, eventually gaining the current name, Malawisaurus dixeyi, in 1993. The beds which produced these fossils are of Cretaceous age, though a more precise date has eluded geologists to date; biostratigraphic studies using Ostracods (small Crustaceans with distinctive shells and high species turnover), and the beds are closely related to carbonates that have been dated to between 123 and 111 million years old, based upon potassium-argon geochronology (argon is a noble gas, and cannot be incorporated into rocks, but unstable isotopes of potassium, which decay into argon can, and will then remain in the rock; since this happens steadily at a known rate, geochemists can date rocks by establishing the ratio of radioactive potassium to argon within them), but studies of the Vertebrate fauna preserved within these rocks has suggested a Late Cretaceous origin.

In a paper published in the journal PLoS One on 13 February 2019, Kate Andrzejewski, Michael Polcyn and Dale Winkler of the Roy M. Huffington Department of Earth Sciences at Southern Methodist University, Elizabeth Gomani Chindebvu of Culture and Community Development at the Ministry of Civic Education in Malawi, and Louis Jacobs, also of the Roy M. Huffington Department of Earth Sciences at Southern Methodist University, describe new Malawisaurus dixeyi material from Malawi, including a reconstruction of the inner ear and endocast (cast of the inside of the braincase, this is not the same as the brain, but can give information about it), and draw conclusions from this.

The described specimen, Mal-202-1, comprises a nearly complete basicranium and associated parietals, ectopterygoid, quadrate, cervical vertebrae, and post cranial elements, all assigned to Malawisaurus dixeyi, recovered from near Mwakasyunguti in Karonga District, northern Malawi, by the Malawi Dinosaur Project in the 1980s and 90s.

The specimen was scanned at the University of Texas High Resolution X-ray CT facility, enabling Andrzejewski et al. to construct a three dimensional computer model of the brain endocast and inner ear. The bones of the braincase are well preserved, and all show fully ossified sutures, suggesting that the specimen was a mature adult at time of death. An estimate of its size based upon the circumference of the humerus, suggests a living weight of 4.73 tonnes.

Braincase of Malawisaurus dixeyi. (A) lateral view; (B) lateral view with endocast; (C) posterior view. Abbreviations: BO, basioccipital; BP, basipterygoid process; BT, basal tuber; CAR, canal for cerebral carotid artery; FO, fenestra ovalis; LABYR, labyrinth; LS, laterosphenoid; OC, occipital condyle; PFO, pituitary fossa; PP, paroccipital process; SO, supraoccipital; SPHA, canal for sphenopalatine artery; III, oculomotor nerve; IV, trochlear nerve; V, trigeminal nerve; VI, abducens nerve; VII, facial nerve; IX-XI, shared canal for glossopharyngeal, vagus, and spinal accessory nerves; XII, hypoglossal nerve. Scale bar equals 10cm. Andrzejewski et al. (2019).

Andrzejewski et al.’s reconstruction lacks the olfactory and cerebral regions, or caudal dural expansion, a prominent venous feature of Sauropods. Like most Sauropod endocasts it shows a lack of distinction of gross regions of the brain, presumably obscured by the presence of overlying thick meninges and extensive venous sinuses in life, but does show typical Sauropod features such as a large pituitary fossa. The reconstruction does show the connections of the veinous canals (canals through which the veins pass) and cranial nerves, the general pattern of which are consistent with the interpretation of Malawisaurus as a Titanosaur.

Cranial endocast and vestibular labyrinth of Malawisaurus dixeyi. (A) left lateral view; (B) caudal view; (C) ventral view; (D) dorsal view; dashed line represents reconstruction of full endocast based on the endocast of Sarmientosaurus. Endocast represented by purple colouring; cranial nerves by yellow colouring; vestibular labyrinth by pink colouring; carotid artery by red colouring. Scale bar equals 5cm. Andrzejewski et al. (2019).

The inner ears of several Sauropods have been described previously, with a general pattern observed of larger vestibular labyrinths in early members of the group, and smaller in more derived Titanosaurs; that of Malawisaurus dixeyi appears to be intermediate in size, which is roughly what would be expected based upon current interpretations of its phylogenetic position as a Titanosaur that split from the group early in their history. It also shows uneven size of the semicircular canals, something which is found in earlier Sauropods, but not more derived Titanosaurs, again consistent with the current interpretations of the phylogenetic position of the species.

Left vestibular labyrinth of Malawisaurus dixeyi. (A) lateral view; (B) posterior view; (C) dorsal view. Abbreviations: C, cochlea; CRC, crus commune; CSC caudal (posterior) semicircular canal; FP, fenestra perilymphatica; FV fenestra vestibuli; LSC, lateral semicircular canal; RSC, rostral (anterior) semicircular canal; VE, vestibule of inner ear. Scale bar equals 2cm. Andrzejewski et al. (2019).

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Monday, 18 February 2019

The closest Lunar Perigee of 2019.

At 9.07 am GMT on Tuesday 19 February 2019 the Moon will be at its closest point to the Earth in 2019, at a distance of 356 761 km. his will fall six hours and forty six minutes before the Full Moon, at 3.53 pm, making it particularly large in the sky. The Moon completes one orbit about the Earth every 27.5 days, and like most orbiting bodies, its orbit is not completely circular, but slightly elliptical, so that the distance between the two bodies varies by about 3% over the course of a month. This elliptical orbit is also not completely regular, it periodically elongates then returns to normal, making some perigees closer than others. These cycles mean that the Moon often reaches its furthest point from the Earth (apogee) of the year in the same lunar cycle, this time reaching 406 390 km at 11.27 am GMT on Monday 4 March, which will be the most distant Lunar Apogee of 2019.

  Simplified diagram of the Moon's orbit. NASA.

Although this is the closest point to the Earth that the Moon has reached this year, it is not exceptional. The Moon reached 356 565 km from the Earth on 1 January 2018, and will reach 356 569 km from the Earth on 21 January 2023.
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Sunday, 17 February 2019

Ceratogyrus attonitifer: A new species of Horned Baboon Spider from Angola.

Baboon Spiders, Harpactirinae, are large Mygalomorph Spiders (Tarantulas) found in Africa. They inhabit silk-lined burrows on the ground, from which they ambush prey, and which they will defend aggresively against any percieved threat with a painful venemous bite; this bite is reputed to be so painful that even Baboons will leave these Spiders alone. Members of the genus Ceratogyrus are widespread in Southern Africa, and are given the popular name Horned Baboon Spiders due to a large foveal horn found on the sternum of some species.

In a paper published in the jouranl African Invertebrates on 6 February 2019, John Midgley of the National Geographic Okavango Wilderness Project of the Wild Bird Trust, the Department of NaturalSciences at the KwaZulu-Natal Museum, and the Southern African Forensic Entomology Research Laboratory at Rhodes University, and Ian Engelbrecht of the South African National Biodiversity Institute and the Department of Zoology and Entomology at the University of Pretoria, describe a new species of Ceratogyrus from the Okavango catchment of Angola.

The Okavango wetland system is best known from Botswana, where it has been a major tourist attraction for decades, as well as being home to numerous scientific studies and television documentaries, but the system actually falls across three counries, Botswana, Namibia and Angola, with the majority in Angola. This Angolan part of the Okavango has recieved relatively little outside attention due ro a civil war that statrted shortly after the collapse of the Portuguese colonial empire in 1974, and lasted into the twenty first century. The National Geographic Okavango Wilderness Project has been working in the area since 2015, and aims to study the entire ecosystem across the three nations of the Okavango, and promote conservation in the area.

The new species is named Ceratogyrus attonitifer, which means 'bearer of astonishment' in reference to the surprise invoked by the discovery of this Spider. The species is described from six female specimens, collected from an undisclosed location within Moxico Province, Angola, during a National Geographic Okavango Wilderness Project in 2016. These are 20.8-40.5 mm in length and golden brown in colour, with the foveal horn much larger than seen in any previously seen member of the genus Ceratogyrus, and soft rather than rigid in nature.

Ceratogyrus attonitifer. (A) Retrolateral view, (B) dorsal view, (C) ventral view. Scale bars are 10 mm. Midgley & Engelbrecht (2019).

Ceratogyrus attonitifer is found in burrows in sandy soil in open Miombo woodland in southeastern Angola. These burrows are near vertical and about 40 cm deep, with a horizonal section at the base. The burrow has a silk colar with local materials such as twigs or grass incorporated. Any object inserted into the burrow was attacked enthusiastically. The Spiders principally feed on Insects, though local people report that the bites can be  serious, and even potenrially fatal if medical help is not available.

Habitat, burrow and live habitus of Ceratogyrus attonitifer in south-eastern Angola. (A) Aerial view of habitat at the type locality showing a dambo (wetland) amongst Miombo (Brachystegia) woodland. The expedition campsite is to the right of the dambo. Specimens were collected primarily along the margins of the wetland area. (B) Live habitus, dorsal, showing full size of the foveal protuberance in life. (C) Specimen in defensive posture typical for Baboon Spiders; background is white sand at the type locality. (D) Burrow entrance amongst grass tussocks; entrance approximately 2 cm wide. Midgley & Engelbrecht (2019).

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Flood at Zimbabwe gold mine kills at least twenty three.

Twenty three bodies have been recovered and it is feared that more than fifty may have died following a flood at a disused gold mine in Mashonaland West Province, Zimbabwe, on Tuesday 12 February 2019. The incident happened at the Cricket Mine at Battlefields, when a retaining dam collapsed allowing water to enter a shaft in which artisanal miners (miners in the informal sector using hand tools) were working. It has not been possible for rescue teams to enter the shaft due to the floodwaters, though pumping equipment has now been brought from nearby mines to attempt to drain the site.

A rescue worker attempts to enter the Cricket Mine in Battlefields, Mashonland West, on 15 February 2019. Jekesai Njikizana/AFP.

The entering of abandoned mines and other sites by artisanal miners is not regarded as illegal in Zimbabwe, a country plagued by high unemployment and other economic problems, and is recognised as making a significant contribution to the economy, as such miners are able to sell their product locally rather than smuggling it out to avoid the attention of local authorities, as happens in many African countries. However, the informal nature of this industry makes it extremely dangerous, as few if any health and safety precautions are taken in such mines, and their are occasional reports of armed clashes between rival groups over lucrative sites.

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