Friday 31 March 2017

Magnitude 5.0 Earthquake on the coast of Managua Department, Nicaragua.

The United States Geological Survey recorded a Magnitude 5.0 Earthquake at a depth of 80 km, on the coast of Managua Department, Nicaragua, slightly 11.00 am local time (slightly before 5.00 pm local time on Wednesday 29 March 2017. Theere are no reports of any damage or casualties associated with this event, though it was felt locally.

The approximate location of the 29 March 2017 Managua Earthquaek. USGS.

Nicaragua is located on the southern part of the Caribbean Plate, close to its boundary with the Cocos Plate, which underlies part of the east Pacific. The Cocos Plate is being pushed northwards by expansion of the crust along the East Pacific Rise, and is subducted beneath the Caribbean Plate along the Middle American Trench, which runs parallel to the south coast of Central America, passing under the peninsula  as it sinks into the Earth's interior. This is not a smooth process, the plates tend to stick together, breaking apart again once the pressure from the northward movement of the Cocos Plate builds up to much, triggering Earthquakes. 

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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Daspletosaurus horneri: a new species of Tyrannosaurid Dinosaur from the Late Cretaceous of Montana.

Tyrannosaurs are possibly the most iconic of all Dinosaurs, appearing in almost all Dinosaur-related fiction and among the most popular exhibits in museums of palaeontology. They were large, bipedal carnivorous Therapods from the Late Cretaceous of North America and Asia, noted for their reduced forearms and (in fictional accounts) presumed ferocity. Tyrannosaur remains are quite numerous in some North American deposits, and the group has been extensively studied, though these studies have concentrated largely on the diet and locomotion of the animals, with other areas of their biology often neglected.

In a paper published in the journal Scientific Reports on 30 March 2017, Thomas Carr of Carthage College, David Varricchio of the Department of Earth Sciences at Montana State University, Jayc Sedlmayr of the Louisiana State University Health Sciences Centre, Eric Roberts of Geosciences at James Cook University and Jason Moore of Honors College at the University of New Mexico describe a new species of Tyrannosaurid Dinosaur from the Late Cretaceous Two Medicine Formation of Glacier, Lewis and Clark and Teton counties in Montana.

The new species is placed in the genus Daspletosaurus, as it is thought to be closely related to the only previously described species in this genus, Daspletosaurus torosus, and given the specific name horneri, in honour of the distinguished American palaeontologist Jack Horner, for his extensive work on the Two Medicine Formation and mentoring of many students who went on to become leaders in the field. The species is described from a complete skull, partial pectoral limb, and nearly complete hind limb, thought to come from one animal, with several other specimens referred, including an incomplete skull, partial axial series, and partial pelvic girdle and hind limb, a nearly complete dentary of a small juvenile, a maxilla, partial postorbital, and parietal, a partial mandibular ramus, a left ectopterygoid and a right ectopterygoid. 

Skull and jaws of Daspletosaurus horneri; (A) photograph and, (B) labeled line drawing of skull and jaws in left lateral view; (C) photograph and, (D) labelled line drawing of occiput and suspensorium in caudal view; (E) photograph and, (F) labelled line drawing of skull in dorsal view. Scale bars equal 10 cm. Carr et al. (2017).

The largest specimen of Daspletosaurus horneri is estimated to have been 9 m in length and 2.2 m at the acetabulum (hip joint). The species has a distinctly wide dental arcade at the front of the snout compared to other Tyrannosaurids, and shows a reduction in tooth numbers in the oldest specimens, something that has been recorded in some other Tyrannosaurids, including Daspletosaurus torosus and Tyranosaurus rex (Tyrannosaurs, unlike Mammals, continuously shed and grew new teeth throughout their lives, so that the number and positioning of teeth was not fixed; this meant that as the animals grew and their jaws got longer the number of teeth tended to increase, but in some species, including Daspletosaurus horneri, the adults have a slightly reduced tooth count compared to the oldest subadults).

 The growth series of Daspletosaurus horneri, based on parsimony analysis. Unambiguously optimized derived phylogenetic characters were recovered as synontomorphies at two of the five growth stages, which are labeled at the corresponding numbers. Scale bar equals 10 cm. Abbreviations: AMNH FARB, American Museum of Natural History, Fossil Amphibians, Reptiles, and Birds; MOR, Museum of the Rockies. Carr et al. (2017).

Several of the specimens referred to the species show exceptional preservation of the facial bones (premaxilla, maxilla, nasal, lacrimal, jugal, postorbital, squamosal, dentary), enabling Carr et al. to make an assessment of the soft tissue covering of the face. These specimens show a course, hummocky texture to the surface of these bones, similar to that seen in extant Crocodylians, which is assumed to be indicative of a scaly outer integument (skin) like that of Crocodylians.

Also preserved are the neurovascular foramina, channels in the bone through which nerves and blood vessels run. In modern Birds these are limited to the jaw tips, the caudal end of the maxilla, and in a row along the side of the lower jaw, but in Crocodylians they are arranged in repeated rows associated with the positioning of scales; this is also the pattern seen in Daspletosaurus horneri, lending further support to the idea that these animals had a face covered by a Crocodile-like scaly skin.

These neurovascular foramina are very numerous and densely packed, which is taken to be indicative of a highly sensitive snout. This is also seen in modern Crocodylians, where the facial skin plays an important role in a number of behaviours, most notably detecting movements in water that could indicate potential prey, and monitoring the temperature of nesting sites (very important for Crocodylians, which have a temperature dependent method of sex determination). Tyrannosaurids are thought to have been terrestrial hunters, making it highly unlikely that they would have used sensitive facial skin to detect movements in the water, and though Carr et al, consider it quite likely that they had a temperature dependent sex determination system and a consequent need to asses the temperature of nesting sites, they feel that this in itself would be unlikely to be the sole reason for the high levels of  neurovascular development in the face of Daspletosaurus horneri. Instead they suggest that this area of skin may have been important in tactile communication, possibly with Tyrannosaurs touching or rubbing one another's faces during courtship.

The craniofacial epidermis of Daspletosaurus horneri, based on comparison with its closest living relatives, Crocodylians and Birds. Bone texture indicates large zones of large, flat scales and subordinate regions of armor-like skin and cornified epidermis; integumentary sense organs occur on the flat scales that cover the densest regions of neurovascular foramina. The region outside of the Crocodylian-like skin is reconstructed with small scales after fossilized skin impressions of Tyrannosaurids. Dino Pulerà in Carr et al. (2017).

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Thursday 30 March 2017

Comet 41P/Tuttle-Giacobini-Kresak passes the Earth.

Comet 41P/Tuttle-Giacobini-Kresak will pass the Earth at a distance of 21 240 000 km (0.14 times the distance between the Earth and the Sun) slightly after 0.50 am GMT on Saturday 1 April 2017, its closest approach to the planet this year. Sadly the comet will not be naked-eye-visible, achieving a maximum magnitude of about +8, which means it should be visible with a small telescope or good pair of binoculars.

Image of 41P/Tuttle-Giacobini-Kresak taken on 6 March 2017 by Dwight Talley of Albuquerque in New Mexico, using a TEC 140 mm telescope and a QSI 660 camera. The comet is the point at the centre of the image, the elongate objects are stars, which appear linear as the telescope remained pointing at the comet, which was moving relative to the stars, over a 120 second exposure. Cloudy Nights.

41P/Tuttle-Giacobini-Kresak was discovered on 3 May 1858 by Horace Parnell Tuttle of the Harvard Observatory, and rediscovered independently by Michel Giacobini of the Nice Observatory in 1907 and Ľubor Kresák of the Skalnate Pleso Observatory in 1951. The designation 41P implies that it was the 41st periodic comet ever discovered.

The calculated orbit of 41P/Tuttle-Giacobini-Kresak. The Sky Live/3D Solar System Simulator.

41P/Tuttle-Giacobini-Kresak is a short period, Jupiter Family comet (a comet with a period of less than 20 years) with an orbit angled at less than 30° to the plane of the Solar System), estimated to be about 1.4 km in  diameter. It has a 5.42 year orbital period and an elliptical orbit tilted at 9.23° to the plane of the Solar System, which takes it from 1.04  AU from the Sun (i.e 1.04 times as far from the Sun as the Earth) to 5.12 AU from the Sun (i.e. 5.12 times the average distance between the Earth and the Sun, slightly inside  the orbit of Jupiter).

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Five confirmed deaths as Nigerian Meningitis outbreak reaches the Federal Capital Territory.

Five people have been confirmed dead in an outbreak of Cerebrospinal Meningitis in the Federal Capital Territory of Nigeria this week. Four deaths were recorded in the Durami area of Abuja on Tuesday 28 March 2017, and a fifth death in Dakwa (about 30 km to the northwest) the following day. The victims range in ages from 1 to 29 years, and all developed signs of the disease shortly before dying, though only two, one from Durami and one from Dakwa, have been fully autopsied. The disease has already killed about 270 people in an epidemic centred on Zamfara, Sokoto and Niger states this year, leading to concerns that a vaccination scheme, credited with saving many lives in the country and greatly reducing the annual impact of the disease, may be starting to fail as the disease adapts to the program.

A member of a medical team adminisering vaccinations in Borno State, in northeastern Nigeria. A Clemments-Hunt/World Health Organization.

Meningitis, an infection of the covering of the brain and spinal column can be caused by a number of micro-organisms, though in West Africa it is usually caused by the Bacterium Neisseria meningitides, which causes annual outbreaks in during the Dry Season the African Meningitis Belt, which runs from the Senegambia region on the west to Kenya and Ethiopia in the east. Between five and ten percent of those infected with the disease die within 48 hours of the first onset of symptoms, with the very young most at risk.

The countries of the Africa Meningitis Belt. David Simpson/PATH/Gavi.
Neisseria meningitides is a form of  Betaproteobacteria spread by salivary and respiratory fluids (i.e. by coughing and sneezing, sharing eating utensils etc.). About 10% of the population are thought to be carriers of the disease, without apparent ill effect, but causes disease in others, particularly in children and young adults, occurring as an annual epidemic in parts of Asia and Africa. Symptoms of the disease include fever, headaches, confusion, stiffness and septicaemia, this later being extremely dangerous; patient with  meningacoccal septicaemia develop a vivid purple rash, and about 50% of patients with this symptom typically die.
Nigeria suffered a particularly sever outbreak of Meningitis in 2009, when over a thousand people lost their lives, though since then an extensive vaccination program has been carried out, with an emphasis on targeting young children, which was thought to have brought the disease largely under control, with only 33 fatalities were recorded in 2016. This is likely to indicate the presence of a new strain of the Bacteria, which the current vaccine does not provide protection  against.

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Wednesday 29 March 2017

Magnitude 5.7 Earthquake beneath the Gulf of California.

The United States Geological Survey recorded a Magnitude 5.7 Earthquake at a depth of 10 km beneath the Gulf of California, roughly 74 km off the coast of Sinaloa State, Mexico, at about 8.15 am local time (about 3.15 pm GMT) on Wednesday 29 March 2017. Although this was a large, shallow quake, and therefore potentially dangerous, it occurred some distance offshore, and while there are reports of it being felt over a wide area of Baja California Sur, Sonora and Sinaloa states, there are no reports of any damage or injuries arising from this event.

The approximate location of the 29 March 2017 Gulf of California Earthquake. USGS.

The boundary between the Pacific and North American Plates runs beneath the Gulf of California, with Beja California lying on the Pacific Plate and the Mexican mainland on the North American. The Pacific Plate is moving northwest with regard to the North American Plate, while the North American Plate is moving southeast relative to the Pacific Plate. This creates a transform plate margin along the centre of the Gulf of California, as the two plates slide past one-another, a margin that continues northward under California as the San Andreas Fault. The plates do not move past one-another smoothly, but continuously stick together then break apart as the pressure builds up, leading to regular Earthquakes beneath the Gulf of California and in the surrounding area.

 Map showing the relative movement of the Pacific and North American Plates, and the fault system beneath the Gulf of California. Monterey Bay Aquarium.

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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Tuesday 28 March 2017

Qarmoutus hitanensis: A Marine Catfish from the Late Eocene of the Valley of Whales, Egypt.

Catfish, Siluriformes, are the most abundant group of freshwater Fish, comprising rougly 22% of all Fish found in non-marine waters. While most Catfish groups are exclusively found in freshwater ecosystems, two groups, the Ariidae and Plotosidae, are found in marine waters. The Plotosidae are Eel-like Catfish found in the Indo-Pacific Region, which lack a fossil record, while the Ariidae, are found on continental shelves, brackish waters, and some freshwater ecosystems in tropical regions around the Atlantic, Indian and Pacific Oceans. The Ariidae first appear in the fossil record in the Cretaceous of North America, reaching Europe in the Palaeocene and Africa and Asia in the Eocene. The Eocene fossil record of the Ariidae in Afrca comprises fragmentary material from Nigeria,  Libya and Egypt, but to date no intact specimens.

In a paper published in the journal PLoS One on 1 March 2017, Sanaa El-Sayed, Mahmoud Kora and Hesham Sallam of the Vertebrate Paleontology Center at Mansoura University, Kerin Claeson of the Department of Anatomy at the Philadelphia College of Osteopathic Medicine, Erik Seiffert of the Department of Cell and Neurobiology at the University of Southern California, and Mohammed Antar of the Department of Geology and Paleontology at the Egyptian Environmental Affairs Agency, describe a new species of Ariid Catfish from the Qarun Formation of the the Wadi El-Hitan (Valley of the Whales) site of the Fayum Depression of northern Egypt.

The Wadi El-Hitan location is noted for the production of numerous intact Vertebrate fossils, notably Whales (hence the name) from a shallow marine environment. It is home to the earliest known fully marine Whales, but has also produced a variety of other fossils, including Crocodiles, Sirenians and Fish. The site was made a UNESCO World Heritage Site in 2005.

The new species is named Qarmoutus hitanensis, where 'Qarmoutus' derives from the Arabic word for Catfish and 'hitanensis' means 'from Hitan'. The species is described from a series of disarticulated elements presumed to have come from a single individual, namely a nearly complete neurocranium, a partial right dentary, a pair of opercles, a left suspensorium, a left pectoral girdle (cleithrum articulated with pectoral spine), the first and second dorsal spines, two paired nuchal plates, the Weberian apparatus and three disarticulated abdominal vertebrae. These are estimated to be about 37 million years old, and can be confidently assigned to the Ariidae due to their distinctive surface sculpture.

 Dorsal view of the left neurocranium and nuchal plates of Qarmoutus hitanensis. (A) Photograph and (B) Line drawing. Anatomical abbreviations: afo, anterior cranial fontanelle; anp, anterior nuchal plate; ar.pstt, articulation facet for posttempro-supracleithrum; ext, extrascapular; fn, fenestra; fopth, foramen for ophthalmic nerve; fr, frontal; le, lateral ethmoid; le.lh, lateral ethmoid lateral horn; me, mesethmoid; mg, medial groove of the neurocranium; pnp, posterior nuchal plate; prp4, parapophysis of the fourth vertebra; pt, pterotic; sc, symplectic canal; sp, sphenotic; suoc, parieto-supraoccipital; suoc. pr, parieto-supraoccipital process;, Weberian compound cenrum; 1st ptg, first pterygiophore. El-Sayed et al. (2017).

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