Saturday, 31 December 2016

Machairodus horribilis: A new, excepionally large specimen of a Sabretooth Cat from the Late Mioene of Gansu Province, China.

Sabretooth Cats, Machairodontinae, were large Felids (Cats) distinguished by their exceptionally long canine teeth and exceptionally wide gapes. They first appeared in the Miocene in Africa and the Middle East and persisted till the beginning of the Holocene, leading to speculation that their demise may have been related to the activities of early Modern Humans. Late members of the group were comparable in size to modern Lions and Tigers, and are presumed to have targeted similarly sized prey, though earlier members of the group were smaller. However one early genus of Sabretooths, Machairodus, did produce similarity large specimens from the Late Miocene onwards, though these animals were less highly specialised than later members of the group, with less prominent teeth and narrower gapes, making their ecology harder to understand.

In a paper published in the journal Vertebrata PalAsiatica in October 2016, Deng Tao of the Key Laboratory of Vertebrate Evolution and Human Origins at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, the Center for Excellence in Tibetan Plateau Earth Sciences and the Department of Geology at Northwest University, Zhang Yun-Xiang, also of the Department of Geology at Northwest University, Zhijie Tseng of the Division of Paleontology at the American Museum of Natural History and Hou Su-Kuan, also of the Key Laboratory of Vertebrate Evolution and Human Origins at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, describe a new specimen of the Sabretooth Cat Machairodus horribilis from the Late Miocene Hipparion Red Clay of Wudu County in Gansu Province in northwestern China.

The new specimen is a skull assessed to be an adult based upon the eruption and wear of the teeth and the fusion of the bone sutures. The specimen is 415 mm in length, longer than the previous largest described specimen of the species, at 353 mm, and also the previous largest previously described member of the genus, a specimen of Machairodus giganteus measuring 355 mm.

Skull of Machairodus horribilis from Longjiagou (Wudu, Gansu Province, China) (A) dorsal view; (B) reconstruction in dorsal view; (C) lateral view; (D) reconstruction in lateral view; (E) ventral view; (F) reconstruction in ventral view Abbreviations: ab. auditory bulla; apf. anterior palatine foramen; C. upper canine; coc. central occipital crest; eam. external auditory meatus; F. frontal bone; fls. fossa for lacrimal sac; fm. foramen magnum; fpp. frontal postorbital process; gf. glenoid fossa; I3. upper third incisor; if. infraorbital foramen; M. maxillary bone; M1. upper first molar; mf. maxillary foramen; mp. mastoid process; mrb. median ridge of the basioccipital; N. nasal bone; nfs. naso-frontal suture; no. nasal opening; oco. occipital condyle; ocr. occipital crest; opf. optic foramen; orf. orbital foramen; P2. upper second premolar; P3. upper third premolar; P4. upper fourth premolar; pc. parietal crest; pf. palatine fissure; pg. palatine groove; plf. posterior lacerated foramen; Pm. premaxillary bone; pn. posterior nares; pog. postglenoid process; pp. paroccipital process; pr. palatine ridge; prg. preglenoid process; sc. sagittal crest; spf. sphenopalatine foramen; tc. temporal crest; tf. temporal fossa; zpp. zygomatic postorbital process. Deng et al. (2016).

All large modern predatory Mammals are capable of taking prey larger than themselves, and indeed need to do so to meet their energetic requirements. This is is also thought to have been the case with the large Sabretooth Cats of the Pleistocene, although their hunting technique is thought to have been somewhat different to that of modern Big Cats, relying on a slashing bite that caused the prey to bleed to death, rather than a suffocating death grip. However members of the genus Machairodus lacked the heavy musculature and wide gape of later Sabretooths, being rather slender in build and having a gape of about 70° rather than the 120° of the later Smilodon. This would seem quite unsuitable for bringing down much larger prey, suggesting that Machairodus must have had a different feeding strategy.

The Mammalian fauna of the Hipparion Red Clay of Wudu County is well extremely well known, giving this locality the potential to provide insight into the feeding ecology of Machairodus horribilis. The only potential prey species larger than Machairodus horribilis available were the Giraffes Samotherium and Honanotherium, which appear to have been much to large to have been targeted by Sabretooths (modern Lions seldom target Giraffes either). However the area was home to large herds of the short-legged Horse Hipparion platyodus, living in a fairly open steppe environment. Most Cats are essentially ambush predators, reliant on seizing and overpowering prey quite quickly, and the large Pleistocene Sabretooths are generally assumed to have hunted in a similar fashion. However the open grassland ecosystem preserved in the Hipparion Red Clay would appear to have been poorly suited to such a strategy, but would have been a good environment for a predator capable of running down smaller prey bursts of high speed activity in a manner similar to that of a modern Cheetah, then killing it with a slashing bite. This in turn suggests that such a strategy may have been typical of the earliest members of the Machairodontinae, with members of the genus Machairodus able to reach large sizes early in the group's history due to an available source of large, relatively slow prey, but other members of the group not reaching similar sizes until Thieu had switched to an ambush-hunting strategy.

See also...
Follow Sciency Thoughts on Facebook.

Friday, 30 December 2016

Rescue operation underway after collapse at Indian coal mine.

The bodies on nine workers have been recovered and another 23 are missing following the collapse of a wall during active excavation at an open cast coal mine at Rajmahal in Jharkhand State, India, on Thursday 29 December 2016. A further four miners have been pulled out of the debris alive, one of whom is described as being in a serious condition. The incident is reported to have happened at about 8.30 pm local time, during a shift change at the pit, when a wall of soil and rock collapsed onto workers and vehicles inside the mine area.

A partially buried vehicle following the 29 December 2016 Rajmahal mine collapse. Press Trust of India.

The incident happened at the Latmatia Mine, which is operated by Eastern Coalfields Ltd, however the rescue operation is being led by Coal India, in coordination with local police, workers from the National Disaster Management Authority, and a specialist mine rescue team sent by the National Disaster Response Force from Patna. An investigation into the incident is being led by a team sent by the Director General of Mines Safety.

See also...
Follow Sciency Thoughts on Facebook.

The Earth approaches its perihelion.

On Wednesday 4 January 2017 at 2.17 am, GMT, the Earth will reach its perihelion; the closest point on its orbit to the Sun, when it will be 147 100 998 km from the Sun. This is because the Earth's orbit is not a perfect circle, but varies by 3.3% over the course of a year. The Earth will reach its furthest point from the Sun, at a distance of 152 092 504 km, at 9.11 pm GMT on 3 July 2016. This perihelion distance varies each year; in 2016 the Earth reached 147 100 176 from the Sun and in 2018 it will reach 147 097 233. 

The Earth's Aphelion and Perihelion. My Dark Sky.

This means that the Earth is at its closest to the Sun in the middle of the Northern Hemisphere's winter, counterintuitive to most of the planet's population. This is, however, purely coincidental; the Earth's season's are not caused by its distance from the Sun, which only varies by 3.3%, but rather by the tilt of the planet. The Earth is currently tilted at an angle of 25.5° to its plane of orbit (this varies on a timescale of tens of thousands of years, but remains fixed from the point of view of any human observer), causing the Sun to appear to rise higher and lower in the skies of each hemisphere as the year goes by. In the northern winter the Southern Hemisphere is tilted towards the Sun, so that the days are longer there (and in around the Southern Solstice in December, permanently above the horizon at the South Pole). In addition the Sun being directly overhead means that the energy from the Sun has to pass through less of the atmosphere before it reaches the surface of the Earth, so that less energy is lost to the atmosphere, causing the surface to warm.
 How the tilt of the Earth relative to its plane of orbit causes the seasons. ESA.
 See also...
Follow Sciency Thoughts on Facebook.

Earthquake swarm hits Mineral County, Nevada.

The United States Geological Survey recorded swarm of Earthquakes in western Nevada, beginning with a pair of a Magnitude 5.7 Earthquake at a depth of 8-12 km, slightly under 30 km to the southwest of the town of Hawthorne in Mineral County in western Nevada, at about 0.20 am local time (about 8.20 am GMT) on Wednesday 18 December 2016. About 50 quakes, mostly quite small, were recorded in the same area during the next 24 hours. There are no reports of any serious damage or injuries associated with this quake, but some damage to properties has been reported in rural areas of  Mineral County, as well as some road closures due to landslips. The events were felt across much of Nevada and California.

Damage to a property on a ranch in Mineral County, Nevada, following the 28 December 2016 Earthquakes. David Ziegler/KoloTV.

Nevada is a zone of active mountain orogeny (mountain growth), fuelled by the subduction zone on the American West Coast. The state is criss-crossed by faults associated with its many growing mountain ranges, which form part of the Rockies. The rocks of the North American lithosphere are being pushed to the east by seafloor spreading beneath the Pacific and to the west by seafloor spreading beneath the Atlantic. This results in folding and upthrust within the plate, principally in the Rocky Mountains, which run along the western margin of the North American Plate, close to the subduction and fault zones of the continent's west coast. This folding and thrusting leads to frequent Earthquakes throughout the Rocky Mountain region, with Nevada being one of America's most quake-prone states.

 The approximate location of the 28 December 2016 Mineral County Earthquake swarm. USGS.

See also...
Follow Sciency Thoughts on Facebook.

Thursday, 29 December 2016

Promecidia abnormis & Promecidia chui: Two new species of Velvet Ants from south China.

Velver Ants, Mutillidae, are a group of Wasps in which the females are flightless and lack wings, causing them to resemble large, fur covered Ants. The males are winged and capable of flying, seeking out females with which to mate. These Wasps are parasitoids (i.e. their larvae live within the bodies of other Insects, slowly consuming their hosts as they grow) targeting other species of ground-dwelling Wasps and Bees, which the females enter, laying individual eggs close to the larvae or pupas of the host. Targeting other Hymenopterans is a high-risk strategy, and female Velvet Ants are noted for their particularly tough exoskeletons and extremely potent stings.

In a paper published in the journal ZooKeys on 16 December 2016, Arkady Lelej of the Institute of Biology and Soil Science of the Russian Academy of Sciences, Hu-ting Zhou of the Department of Entomology at South China Agricultural University, Valery Loktionov, also of the Institute of Biology and Soil Science of the Russian Academy of Sciences and Zai-fu Xu, also of the Department of Entomology at South China Agricultural University, describe two new species of Velvet Ants from south China, as part of a review of Velvet Ants of the genus Promecidia.

The first new species described is named Promecidia abnormis, in reference to the presence of a carina (ridge) on the second sternal segment of the male, which is a common feature in members of the genus Zeugomutilla, but which is highly unusual in a member of the genus Promecidia. The species is described from two male specimens, one collected from the Nankunshan Provincial Nature Reserve in Guangdong Province and the second from the Jianfengling National Nature Reserve on Hainan Island. These are 8.5 and 10.2 mm in length respectively, and black in colour with a distinctive reddish brown area on their backs.

Promecidia abnormis, male specimen from Guangdong Province. Scale bar is 1 mm in length. Lelej et al. (2016).

The second new species is named Promecidia chui, in honour of the Chinese entomologist Chu Joo-tsu, an expert on the Hymenoptera. This species is described from twelve male and one female specimens from several locations in Yunnan and Hainan Provinces. The males range from 6.8 to 11.9 mm in length and black with reddish brown markings, the female is 7.65 mm in length and reddish brown with black and yellow markings.

Promecidia chui, male specimen from the Nabanhe National Nature Reserve in Yunnan Province. Scale bar is 1 mm. Detail of mandible inset. Lelej et al. (2016).

 Promecidia chui, female specimen from the Diaoluoshan National Nature Reserve on Hainan Island. Inset bottom left: Metasoma, dorsal view. Inset bottom right: Metasomal terga 5 and 6, dorsal view. Scale bar 1 mm. Lelej et al. (2016).

See also...
Follow Sciency Thoughts on Facebook.

Landslide at Myanmar jade mine may have buried as many as forty people.

It is feared that as many as forty people may be buried beneath a landslip at a jade mine in Hpakant in Kachin State, Myanmar, that occurred late on Wednesday 28 December 2016, when a 120 m exposed face on the side of a spoil heap produced by a large mining concern collapsed onto smaller artisanal miners looking for pieces of jade missed by the larger operation.

 Artisanal miners on a spoil heap in Hpakant. Al Jazeera.

Myanmar is the world's largest producer of jade, though much of this is produced (along with other precious and semi-precious minerals such as amber) at unregulated (and often illegal) artisanal mines in the north of the country, from where it is smuggled into neighbouring China. Accidents at such mines are extremely common, due to the more-or-less total absence of any safety precautions at the site. At many sites this is made worse by the unregulated use of explosives to break up rocks, often leading to the weakening of rock faces, which can then collapse without warning. The majority of people in this industry are migrant workers from the surrounding countryside, not registered with any local authority, which can make it difficult for rescuers to identify victims following such events, or even gain accurate assessments of the number of people likely to have been involved in such accidents.

The approximate location of the Hpakant jade mines. Google Maps.

See also...
Follow Sciency Thoughts on Facebook.

Asteroid 2011 YG6 passes the Earth.

Asteroid 2011 YG6 passed by the Earth at a distance of about 17 940 000 km (47.0 times the average distance between the Earth and the Moon, or 12.0% of the distance between the Earth and the Sun), slightly after 5.10 am GMT on Thursday 22 December 2016. There was no danger of the asteroid hitting us, though were it to do so it would have presented a considerable threat. 2011 YG6 has an estimated equivalent diameter of 110-360 m (i.e. it is estimated that a spherical object with the same volume would be 110-360 m in diameter), and an object of this size would be predicted to be capable of passing through the Earth's atmosphere relatively intact, impacting the ground directly with an explosion that would be 600-118 000 times as powerful as the Hiroshima bomb. Such an impact would result in an impact crater 1.5-5 km in diameter and devastation on a global scale, as well as climatic effects that would last decades or even centuries.

The calculated orbit of 2011 YG6. Minor Planet Center.

2011 YG6 was discovered on 24 December 2011 by the University of Arizona's Catalina Sky Survey, which is located in the Catalina Mountains north of Tucson. The designation 2011 YG6 implies that it was the 157th asteroid (asteroid G6) discovered in the second half of December 2011 (period 2011 Y).
2011 YG6 is calculated to have a 459 day orbital period and an elliptical orbit tilted at an angle of 28.1° to the plain of the Solar System that takes it from 0.82 AU from the Sun (i.e. 82% of the average distance at which the Earth orbits the Sun) to 1.51 AU from the Sun (i.e. 151% of the average distance at which the Earth orbits the Sun, slightly more than the distance at which the planet Mars orbits the Sun). It is therefore classed as an Apollo Group Asteroid (an asteroid that is on average further from the Sun than the Earth, but which does get closer). This means that close encounters between the asteroid and Earth are extremely common, with the last having occurred in December 2011 and the next predicted in December 2021. As an asteroid possibly larger than 150 m in diameter that occasionally comes within 0.05 AU of the Earth, 2011 YG6 is also classified as a Potentially Hazardous Asteroid. 
See also...

Follow Sciency Thoughts on Facebook.

Preserved plumage in an immature Bohaiornithid Bird from the Jehol Biota.

The Bohaiornithids were an early group of Enantiornithine Birds (a group of Toothed Birds dominant in many Cretaceous faunas; the modern Euornithine Birds having come to prominence only after the End Cretaceous Extinction). The Bohaiornithids are known from the Jiufotang and Yixian Formations, together the Jehol Biota, giving them a chronological range from 125 to 120 million years ago.

In a paper published in the journal Palaeontology on 13 November 2016, Jennifer Peteya of the Department of Biology and Integrated Bioscience Program at the University of Akron, Julia Clarke of the Department of Geological Sciences at the University of Texas at Austin, Quangou Li of the State Key Laboratory of Biogeology and Environmental Geology at the China University of Geosciences, Ke-Qin Gao of the School of Earth and Space Sciences at Peking University and Matthew Shawkey, also of the Department of Biology and Integrated Bioscience Program at the University of Akron and of the Terrestrial Ecology Unit at the University of Ghent describe a new Bohaiornithid specimen with well preserved plumage from the Early Cretaceous Jiufotang Formation of Liaoning Province in northeastern China.

The new specimen is adjudged to be a subadult based upon the development of its skeleton. It does not appear to be a member of any previously described species of Bohaiornithid, but since the ontogeny (development) of these Birds is not well understood, Peteya et al. refrain from describing it as a member of a new species. However despite lacking a fully mature skeleton, the specimen appears to have full adult plumage; this is different to the situation in modern Birds, which do not gain their full adult plumage, or ability to fly, until they are fully mature.

Ventral view of the new Bohaiornithid specimen. (A) Photograph of the primary slab. (B) Interpretive drawing. Abbreviations: co, coracoid; cv, cervical vertebrae; fe, femur; fu, furcula; hu, humerus; il, ilium; mcI–III, metacarpals I–III; mt, metatarsals; pd I–IV, pedal digits I–IV; phI-1, first phalanx of digit I; phII/III-1/2, first/second phalanx of digit II/III; pu, pubis; py, pygostyle; ra, radius; sc, scapula; sk, skull; sml, semilunate carpal; st, sternum; sy, synsacrum; th, thoracic vertebrae; ti, tibia; ul, ulna; uln, ulnare. Scale bar represents 1 cm. Peteya et al. (2016).

Close examination of the plumage of the specimen revealed the presence of preserved melanosomes (pigment bearing-cells). When these cells were analysed using Raman spectroscopy, suggested that three different types of melanosomes were present, associated with black, brown and iridescent colouring. While it was not possible to tell the colour of the iridescent plumage was impossible to tell, but the presence of iridescent colouring in a Bird that was not fully grown is interesting. In modern Birds the presence of iridescent plumage is always associated with sexual maturity, often coming some time after the Bird reaches physical maturity. If the iridescent feathers of the Jehol Bird are also associated with sexual maturity, then it implies that this Bird reached sexual maturity before it was fully grown. This is completely different from the situation seen in modern Birds, but is similar to that seen in their closest living relatives (and the only other surviving Archosaur group) the Crocodylians, in which sexual maturity is reached long before full size is achieved.

See also...
Follow Sciency Thoughts on Facebook.