Friday, 31 July 2015

Magnitude 1.3 Earthquake near Glencoe, Scotland.

The British Geological Survey recorded a Magnitude 1.3 Earthquake at a depth of about 10 km about 5 km to the west of Glencoe in the district of Lochaber in Highland, Scotland, slightly after 9.25 pm British Summertime (slightly after 10.35 pm GMT) on Thursday 20 July 2015. This was not a major event, and presented no threat to human life or property, but was felt in the village of Ballachulish.

The approximate location of the 20 July 2015 Lochaber Earthquake. Google Maps.

Earthquakes become more common as you travel north and west in Great Britain, with the west coast of Scotland being the most quake-prone part of the island and the northwest of Wales being more prone  to quakes than the rest of Wales or most of England. 

The precise cause of Earthquakes in the UK can be hard to determine; the country is not close to any obvious single cause of such activity such as a plate margin, but is subject to tectonic pressures from several different sources, with most quakes probably being the result of the interplay between these forces.

Britain is being pushed to the east by the expansion of the Atlantic Ocean and to the north by the impact of Africa into Europe from the south. It is also affected by lesser areas of tectonic spreading beneath the North Sea, Rhine Valley and Bay of Biscay. Finally the country is subject to glacial rebound; until about 10 000 years ago much of the north of the country was covered by a thick layer of glacial ice (this is believed to have been thickest on the west coast of Scotland), pushing the rocks of the British lithosphere down into the underlying mantle. This ice is now gone, and the rocks are springing (slowly) back into their original position, causing the occasional Earthquake in the process. 

(Top) Simplified diagram showing principle of glacial rebound. Wikipedia. (Bottom) Map showing the rate of glacial rebound in various parts of the UK. Note that some parts of England and Wales show negative values, these areas are being pushed down slightly by uplift in Scotland, as the entire landmass is quite rigid and acts a bit like a see-saw. Climate North East.

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. If you felt this quake, or were in the area but did not (which is also useful information) then you can report it to the British Geological Survey here.

See also...

The British Geological Survey recorded a Magnitude 1.4 Earthquake at a depth of about 2 km off the south coast of the Isle of Mull, in Argyll and Bute, Scotland...


The British Geological Survey recorded a Magnitude 1.3 Earthquake at a depth of about 3 kmto the west of Loch Rannoch in Perth and Kinross, Scotland, slightly...


The British Geological Survey recorded a Magnitude 2.2 Earthquake at a depth of about 11 km to the south of Loch Shiel in...

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Thursday, 30 July 2015

Babibasiliscus alxi: A Casquehead Lizard from the Early Eocene of Wyoming.


Casquehead Lizards, Corytophanidae, are a group of Iguanid Lizards found from the tropical forests of southern Mexico, through Central America to the northwest of South America. They belong to a group of Iguanians, the Pleurodonta, found today almost exclusively in the Americas, with non-American members of the group known only from the islands of Madagascar and Fiji, and studies of the group taking into account relationships between modern species and their biogeographical distribution suggest that they probably originated in the American tropics. However a single fossil specimen of a Casquehead Lizard is known from the Early Eocene of Central Europe, suggesting that their ancient distribution might have been somewhat different from that seen today.

In a paper published in the journal PLoS One on 1 July 2015, Jack Conrad of the Department of Anatomy at the New York Institute of Technology College of Osteopathic Medicine and the Department of Vertebrate Paleontology at the American Museum of Natural History describes a new species of Casquehead Lizard from the late Early Eocene Bridger Formation of Uinta County in Wyoming (about 48 million years old).

The new species is named Babibasiliscus alxi, where ‘Babi-’ means ‘older male cousin’ in the language of the Shoshone people who inhabited the region where the fossil was discovered, and ‘-basiliscus’ (Basiliscus) is the name of a modern genus of Casquehead Lizards, while ‘alxi’ honours John Alexander, who discovered the specimen from which the species was described. The single known specimen comprises a nearly complete skull with articulated jaws plus the first two vertebrae, undistorted or compacted, but with the premaxilla, posterior half of the frontal, parietal, postfrontals, postorbitals, squamosals, supratemporals, supraoccipital, dorsal half of each quadrate, and the anterior tips of both dentaries lost to erosion.

Babibasiliscus alxi: Photographs in (A) right lateral, (B) dorsal, and (C) ventral views. Digital reconstructions derived from High Resolution X-ray Computerised Tomography in (D) left lateral view and (E) transverse section. The vertical red line in (D) indicates the plane of section in (E). Conrad (2015).

A phylogenetic analysis of Casquehead Lizards including Babibasiliscus alxi places it firmly within the modern group, closely related to the living genus Laemanctus. Wyoming is considerably outside the range of modern Casquehead Lizards, with a strongly seasonal climate, typically including heavy winter snowfall. However during the Eocene global climates are known to have been considerably warmer than today, and both Babibasiliscus alxi from Wyoming and Geiseltaliellus maarius from the Eocene of Central Europe are interpreted as having lived in tropical forests not dissimilar from those inhabited by modern Casquehead Lizards.

Phylogeny of Corytophanids and distribution of the group. (A) Time-calibrated phylogeny of the Corytophanid genera with representative illustrations of their skull morphologies. Conrad (2015).

Modern Iguanians are divided into two groups, the Chamaeleontiformes, comprising the Chameleons, Agamas, and their relatives, which are found in the Old World, and the Pleurodonta, comprising the Iguanas, Basilisks, Anoles, Fence Lizards, and their relatives, which are found in the Americas (with the exception of the Opluridae which are found in Madagascar and the genus Brachylophus from Fiji). However the earliest Iguanians are found in Cretaceous deposits dating to before the separation of North America and Eurasia, with the majority of species found in Asia, suggesting this is where the group originated. By the Eocene Iguanians were divided into the modern groups Chamaeleontiformes and Pleurodonta, though with specimens from both groups found on both sides of the Atlantic, and in particular many species of Pleurodonts found in the Old World. It is therefore thought that the modern distribution of the groups reflects a relict distribution shaped by post-Eocene cooling rather than the modern groups having derived from isolated populations after the separation of the continents. Conrad suggests that this interpretation can also be applied to the modern Casquehead Lizards, with the group distributed across tropical forests in what is now the Northern Hemisphere temperate zone during the Eocene (when they were probably excluded from the far hotter tropics), and subsequently having withdrawn to the Neotropics during later Cainozoic cooling.

See also…

Anles are small Iguanid Lizards found in the Southern United States, Mexico, Central America and the Caribbean. Twig Anoles, Norops spp., form a distinct cluster of medium sized Anole Lizard species within the genus Norops. There are currently eight...


Treerunners of the genus Plica are Iguanid Lizards found in South America east of the Andes. They are medium sized, conspicuous Lizards that are active...


Western Europe is thought to have had a diverse Squamate (Snake and Lizard) fauna during the Miocene, but to have largely lost this during the cooling climate of the Plio-Pleistocene, during which...


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Saturday, 25 July 2015

Zhenyuanlong suni: A large feathered Dromaeosaur from the Jehol Biota.


Dromaeosaurid Dinosaurs are among the closest non-Avian relatives of the Birds and show many similarities to the earliest members of that group, making understanding Dromaeosaurs important for understanding the origin of Birds. In particular many Dromaeosaur specimens from the Early Cretaceous of Liaoning Province, China, have been shown to possess extremely Bird-like feather coats, and in several cases feathered wings which may have allowed them to fly. This is particularly interesting as the Liaoning specimens are not thought to represent a tight monophyletic group (i.e. a group of species more closely related to one-another than anything else), but rather a diverse group of Dromaeosaurs with exceptional preservation, part of the Jehol Biota of exceptionally well preserved Early Cretaceous fossils, suggesting that feathers were also present in Dromaeosaurs from other locations even if they have not been preserved. The smallest and most numerous Liaoning Dromaeosaurs are placed in the genus Microraptor and may (or may not) represent several species of small (cat-sized) Dinosaurs fully capable of flight, while the largest, Tianyuraptor, is a much larger animal with reduced fore-limbs highly unlikely to have been capable of supporting it in flight. Unfortunately Tianyuraptor is known only from a single specimen lacking feathers; it is impossible to determine whether this species was truly featherless from a single specimen, nor to speculate about what sort of feathers it may have possessed.

In a paper published in the journal Nature Scientific Reports on 16 July 2015, Junchang Lü of the Institute of Geology of the Chinese Academy of Geological Sciences and the Key Laboratory of Stratigraphy and Paleontology of the Ministry of Land and Resources of China and Stephen Brusatte of the School of GeoSciences at the University of Edinburgh, describe a new species of Dromaeosaur from the Yixian Formation of Jianchang County in Liaoning Province.

The new species is named Zhenyuanlong suni, honouring Zhenyuan Sun who discovered the specimen; the suffix ‘-long’ means ‘Dragon’ in Chinese, making ‘Zhenyuanlong suni’ ‘Zhenyuan Sun’s Dragon’. The specimen comprises an almost complete specimen preserved on in two dimensions on three separate blocks, with only the end part of the tail missing. The specimen is 126.6 cm in length, but it is thought to have been about 165 cm long in life. Not all of the vertebrae fused in adult Dinosaurs are fully fused in this specimen, leading Lü and Brusatte to conclude it was a subadult at the time when it died.

The holotype of the large-bodied Liaoning Dromaeosaurid Zhenyuanlong suni. Lü & Brusatte (2015).

Like Tianyuraptor, Zhenyuanlong suni has relatively small forelimbs for the size of its body, however unlike Tianyuraptor an extensive feather coating is preserved on all of Zhenyuanlong suni except its hindlimbs (these are preserved on a separate block which does not contain any feathers, making it hard to assess whether feathers were originally present on the hindlimbs; feathered hindlimbs are common in both smaller Dromaeosaurs and early Birds). Notably these show layered feathers similar to those seen in modern Birds and Microraptor.

The integument of the large-bodied, short-armed Liaoning Dromaeosaurid Zhenyuanlong suni. (A) Overview of the skeleton with regions of integument indicated with grey highlight; (B) proximal tail; (C) left forearm; (D) right forearm; (E) closeup of coverts on right forearm. Lü & Brusatte (2015).

Without a full biomechanical analysis (which has not been carried out for Zhenyuanlong suni at the time of writing) it is impossible to say whether or not it was capable of flying or gliding, but the combination of a large body size and small forelimbs makes this seem somewhat unlikely, leading to support for the alternative theory that feathered wings were first developed for some other purpose in Bird-like Dinosaurs and later co-opted for flight in Birds and possibly some small Dromaeosaurs. This is not uncommon as evolution does not plan ahead, and major biological revolutions often come about when organs or metabolic pathways adapted to one purpose are then used for another.

See also…

The Dromaeosaurid (a type of small Theropod Dinosaur closely related to Birds and Troodontids) Saurornitholestes langstoni was first...


In December 2000 Xing Xu, Zonghe Zhou and Xioalin Wang of the Institute of Vertebrate Paleontologyand Paleoanthropology of the Chinese Academy of...


Dromaeosaurs were small Therapod Dinosaurs, thought to have been the group most closely related to...

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Thursday, 23 July 2015

Asteroid (242191) 2003 NZ6 passes the Earth.

Asteroid (242191) 2003 NZ6 passed by the Earth at a distance of 12 470 000 km (32.4 times the average distance between the Earth and the Moon, or 8.33% of the average distance between the Earth and the Sun), at about 5.55 pm GMT on Saturday 18 July 2015. There was no danger of the asteroid hitting us, though had it done so it would have presented a considerable threat. (242191) 2003 NZ6 has an estimated equivalent diameter of 300-940 m (i.e. it is estimated that a spherical object with the same volume would be 300-940  m in diameter), and an object of this size would pass through the atmosphere and directly impact the ground with a force of about 1110-1 45 000 megatons (roughly 65 300 to 2 650 000 times the explosive energy of the Hiroshima bomb), causing devastation over a wide area and creating a crater about 4.5-13 kilometers across, and resulting in global climatic problems that could last for decades or even centuries.

The calculated orbit of (242191) 2003 NZ6. JPL Small Body Database.

(242191) 2003 NZ6 was discovered on 9 July 2003 by the Massachusetts Institute of Technology's Lincoln Near Earth Asteroid Research Laboratory in Socorro, New Mexico. The designation 2003 NZ6 implies that it was the 175th asteroid (asteroid Z6) discovered in the first half of July 2003 (period 2003 Z), while the designation 242191 implies that it was 242 191st asteroid ever discovered (asteroids are not given this longer designation immediately to avoid naming double or false sightings).

(242191) 2003 NZ6 has a 258 day orbital period, with an elliptical orbit tilted at an angle of 18.2° to the plain of the Solar System which takes in to 0.43 AU from the Sun (43% of the distance at which the Earth orbits the Sun, slightly outside the orbit of Mecury) and out to 1.18 AU (18% further away from the Sun than the Earth). This means that close encounters between the asteroid and Earth are fairly common, with the last thought to have happened in May 2012 and the next predicted in April 2017. Although it does cross the Earth's orbit and is briefly further from the Sun on each cycle, (242191) 2003 NZ6 spends most of its time closer to the Sun than we are, and is therefore classified as an Aten Group Asteroid. This also means that close encounters between (242191) 2003 NZ6 and Venus are also quite common, with the last having occurred in April 2012 and the next predicted for August this year.

See also...

Asteroid (385186) 1994 AW1 passed by the Earth at a distance of 9 725 000 km (25.3 times the average distance between the Earth and the Moon, or 6.50% of the average distance between the Earth and the...


Asteroid 2011 YC29 passed by the Earth at a distance of 9 438 000 km (24.5 times the average distance between the Earth and the Moon, or 6.31% of the average distance between the Earth and the Sun), at about 10.10 am GMT on Wednesday 15 July...


Asteroid 2015 JH2 passed by the Earth at a distance of 11 830 000 km (30.8 times the average distance between the Earth and the Moon, or 7.91 % of the average distance between the Earth and the Sun), slightly before 2.40 am GMT on Thursday 9 July...



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Eruptions on Nevado del Ruiz.

The Instituto Colombiano de Geología y Minería (INGEOMINAS) reported an increase in seismic activity (earthquakes) beneath Nevado del Ruiz, a 5231 m stratovolcano (cone shaped volcano made up of layers of lava and ash) in the Los Nevados National Natural Park, at the northern end of the Ruiz-Tolima Volcanic Massif in Columbia on Monday 13 July 2015. Such Earthquakes are significant as they are often caused by magma moving in chambers beneath the volcano, and can be indicative of forthcoming eruptions. This was followed by a series of small ash eruptions which lead to ashfalls in villages up to 30 km from the volcano. This activity continued till Saturday 18 July, when the Washington Volcanic Ash Advisory Center reported a large eruption at about 5.30 am which produced an ash column rising 6.1 km above the mountain. A second smaller eruption was reported on 19 July, this time producing an ash column about 1 km in height.

Ash column over Nevado del Ruiz on 19 July 2015. Volcano Discovery.

The Ruiz-Tolima Volcanic Massif runs north-to-south parallel to the Parallel to the Pacific Coast of Columbia. It is fed by the subduction of the Nazca Plate beneath the South American Plate along the Peru-Chile Tench, which runs approximately parallel to the entire western coast of South America. As the Nazca Plate it sinks into the Earth's interior it is heated by the planet's interior heat. This melts minerals within the subducting plate, some of which then rise through the overlying South American Plate as magma, fueling volcanoes in the Andes along the full extent of the South American west coast.

The approximate location of Nevado del RuizGoogle Maps.

See also...

Concern is rising in Colombia and Ecuador following a rise in seismic activity beneath Cerro Negro de Mayasquer, a volcano in the Andes straddling...


The United States Geological Survey recorded a Magnitude 5.0 Earthquake at a depth of 28.4 km in southern Tolima Department, Columbia, at about...


The Observatorio Vulcanológico and Sismológico de Popayán reported a sharp rise in seismic activity under Mount Sotará in southeast Columbia this month, with 110 Earth tremors of magnitudes between 0.2 and 1.6 at depths of 2-6 km, within 5 km of the summit between... 


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Monday, 20 July 2015

Magnitude 1.6 Earthquake in Cumbria, England.

The British Geological Survey recorded a Magnitude 1.6 Earthquake at a depth of about 5 km about five kilometers to the south of the village of Caldbeck in Cumbria, England, slightly before 11.00 pm British Summertime (slightly before 10.00 pm GMT) on Friday 17 July 2015. There are no reports of any injuries associated with this event, though it may have been felt locally.

The approximate location of the 17 July 2015 Cumbria Earthquake. Google Maps.

Earthquakes become more common as you travel north and west in Great Britain, with the west coast of Scotland being the most quake-prone part of the island and the northwest of Wales being more prone  to quakes than the rest of Wales or most of England. However, while quakes in southern England are less frequent, they are often larger than events in the north, as tectonic presures tend to build up for longer periods of time between events, so that when they occur more pressure is released.

The precise cause of Earthquakes in the UK can be hard to determine; the country is not close to any obvious single cause of such activity such as a plate margin, but is subject to tectonic pressures from several different sources, with most quakes probably being the result of the interplay between these forces.

Britain is being pushed to the east by the expansion of the Atlantic Ocean and to the north by the impact of Africa into Europe from the south. It is also affected by lesser areas of tectonic spreading beneath the North Sea, Rhine Valley and Bay of Biscay. Finally the country is subject to glacial rebound; until about 10 000 years ago much of the north of the country was covered by a thick layer of glacial ice (this is believed to have been thickest on the west coast of Scotland), pushing the rocks of the British lithosphere down into the underlying mantle. This ice is now gone, and the rocks are springing (slowly) back into their original position, causing the occasional Earthquake in the process.

(Top) Simplified diagram showing principle of glacial rebound. Wikipedia. (Bottom) Map showing the rate of glacial rebound in various parts of the UK. Note that some parts of England and Wales show negative values, these areas are being pushed down slightly by uplift in Scotland, as the entire landmass is quite rigid and acts a bit like a see-saw. Climate North East.

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. If you felt this quake, or were in the area but did not (which is also useful information) then you can report it to the British Geological Survey here.

See also...

The British Geological Survey recorded a Magnitude 1.7 Earthquake at a depth of 4 km in the Kents Bank area of Morcambe Bay, northwest England, at about 5.55...


The British Geological Survey recorded a Magnitude 1.9 Earthquake at a depth of 10 km about 7 km to the northwest of the town of Ulverston...


The British Geological Survey recorded a Magnitude 2.0 Earthquake at a depth of 12 km about 20 km to the southeast of the town of Kendle in Cumbria...


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Barbatodon transylvanicus: A red-toothed Multituberculate Mammal from the Late Cretaceous of Haţeg Island.


Small, isolated islands often produce distinctive faunas, unlike anything seen on larger landmasses, and have been termed ‘cradles of evolution’ for this reason. Such island faunas are also known in the fossil record, particularly during the Cainozoic, with examples such as the Dwarf Hominids of Flores Island in Indonesia, Pygmy Elephants and Giant Hedgehogs from the Mediterranean and Pygmy Elephants from the Channel Islands of California. Further back in the fossil record distinct landmasses are harder to identify, but one well documented case is Haţeg Island in the modern Transylvanian Basin of southern Romania, where high sea-levels in the Late Cretaceous flooded much of southern Europe. Haţeg Island is estimated to have been about the same size as modern Hispaniola, and has produced a variety of unique Dinosaurs, including Dwarf Sauropods, and a Mammalian fauna dominated by the Kogaionid Multituberculates, an unusual group of Mammals found nowhere else during the Cretaceous, but being one of two Mammal groups in Europe which survived the End Cretaceous Extinction, flourishing briefly during the Palaeocene before becoming extinct as more modern Mammal Faunas invaded Europe from elsewhere (the other group being the equally extinct Adapisoriculidae, tree dwelling Placental Mammals). The lifestyle of Kogaionids, like many other Multituberculates, is somewhat obscure, as most species are known only from isolated teeth, but they are thought to have been similar to modern Rodents or Insectivores.

In a paper published in the journal PLoS One on 15 July 2015, Thierry Smith of the Directorate Earth and History of Life at the Royal Belgian Institute of Natural Sciences and Vlad Codrea of the Faculty of Biology and Geology at University Babeş-Bolyai describe a partial skull of the Kogaionid Multituberculate Barbatodon transylvanicus, previously known only from a single lower molar, from the Late Cretaceous of Haţeg Island.

The new specimen comprises a partial rostrum (snout), the left premaxillary, the left squamosal, both petrosals, and both associated dentaries, along with attached teeth, as well as a number of detached teeth. This allows conformation that Barbatodon transylvanicus is in fact a true species, and not a specimen of Kogaionon ungureanui, as has been previously suggested.

Barbatodon transylvanicus, Maastrichtian, Pui, Romania, specimen UBB P-Mt 1. Partial skull in (A) dorsal, (B) ventral, (C) left lateral, (D) right lateral views; Left squamosal and petrosal (E) and right petrosal (F) in dorsal view; Left premaxillary in (G) lateral view; Left dentary in (H) occlusal, (I) labial, (J) lingual views; Right dentary in (K) occlusal, (L) labial, (M) lingual views. Specimens covered with ammonium chloride. Smith & Codrea (2015).

The crowns of the teeth of Barbatodon transylvanicus are tinted red with iron oxide minerals. This is seen in modern Red-toothed Shrews (Soricinae and Myosoricinae) as well as a variety of Rodents, such as the Brown Rat, Rattus norvegicus, and North American Beaver, Castor canadensis, as well as in some non-Mammals, such as the Axolotl, Ambistoma spp., Piranhas, Characidae, Butterflyfish, Chaetodonidae, and even some Molluscs such as the Limpet, Patella, and the Chiton, Acanthopleura. In all cases the presence of iron minerals is thought to add strength and durability to the teeth, for example in Butterflyfish more iron minerals are associated with a higher Coral content in the diet.

Close-up on tooth rows of Barbatodon transylvanicus. (A) Left dentary with p4-m2 and (B) left maxillary with P1-M2 in occlusal views and covered with ammonium chloride. (C) Left maxillary with P1-M2 in occlusal view; (D) premaxillary with in I2-3 in lateral view; (E) anterior part of right maxillary with P1-2 and (F) right dentary with p4-m2 in lingual view in natural colour. Smith & Codrea (2015).

Iron minerals have previously been identified in the teeth of the Paleocene Asian Taeniolabidoid Multituberculates Lambdopsalis bulla and Sphenopsalis nobilis, suggesting that this may be an ancestral trait found throughout the group, as with Red-toothed Shrews. However in Rodents the trait is thought to have arisen separately on numerous occasions (different iron minerals are found in different Rodent groups), so without further data no such assumption can be made. Tooth enamel is seldom preserved without alteration, and this is the first known example of iron minerals being preserved within the enamel of teeth from any Mesozoic animal, making it unlikely that it will ever be established how widespread this trait was in the largely-Cretaceous Multituberculates.

Reconstruction of the skull and dentary of Barbatodon transylvanicus in (N) dorsal and (O) lateral views. Grey zones indicate missing parts. Smith & Codrea (2015).

See also…

Shrews (Soricidae) are small insectivorous or omnivorous Mammals found across much of the...


Biologists studying modern mammals divide them into...

During the later part of the Cretaceous global sea levels were extremely high, and much of Europe was flooded, leaving he remaining land masses as a string of...


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