Saturday, 19 January 2019

Molluscs from the Early Cambrian Shackleton Limestone of the Central Transantarctic Mountains.

The Early Cambrian Shackleton Limestone outcrops at a number of locations in the Central Transantarctic Mountains. It is thought to be about 2 km thick at its maximum extent, and contains a variety of massive limestones, sandy carbonates, and bioherms (expand), laid down at a time when East Antarctica was located in the tropics. These deposits have produced a range of small shelly fossils assigned including Archaeocyaths (extinct, sessile, reef-building marine organisms of uncertain affinities), Brachiopods, Bradoriid Arthropods, Cambroclavids (phosphatised fossils of uncertain affinities), Chancelloriids (spines that may have come from Sponges or some more advanced group), Hyoliths (conical shelled lophophorate animals), Sponge spicules, and Tommotiids (shelly fossils thought to be related to Brachiopods and Phoronids), which show affinities to similar fossils from other Early Cambrian sites around the world, but in particular those from South Astralia and south China.

In a paper published in the Journal of Paleontology on 9 January 2019, Thomas Claybourn of the Department of Earth Sciences at Uppsala University, and the Department of Biological Sciences at Macquarie University, Sarah Jacquet of the Department of Geological Sciences at the University of Missouri, Christian Skovsted of the Department of Palaeobiology at the Swedish Museum of Natural History, Timothy Topper, also of the Department of Palaeobiology at the Swedish Museum of Natural History, and of the Shaanxi Key laboratory of Early Life and Environments, and the State Key Laboratory of Continental Dynamics at the Department of Geology at Northwest University, Lars Holmer, also of the Department of Earth Sciences at Uppsala University, and the Shaanxi Key laboratory of Early Life and Environments, the State Key Laboratory of Continental Dynamics, and the Department of Geology at Northwest University, and Glenn Brock, also of the Department of Biological Sciences at Macquarie University, describe a series of Mollusc fossils from the Shackleton Limestone.

(1) Map of Antarctica showing approximate extent of the Transantarctic Mountains and area shown in (2). (2) Map of Nimrod Glacier, Holyoake Range, and Churchill Mountains. (3) Generalized relationship of Cambrian (Byrd Group) and Neoproterozoic (Beardmore Group) rock units of the Holyoake Range. (4) Simplified geological map of the Holyoake Range. Claybourn et al. (2019).

The first fossil described is Pojetaia runnegari, a Bivalve previously described from the Early Cambrian of South Australia and Newfoundland. These are small Bivalves with equibivalved shells (shells in which the valves are the same), suboval to subcircular in shape, and 0.8-1.5 mm in length, with a small projection near the hinge.

Pojetaia runnegari from the Shackleton Limestone. (1)–(4) Specimen SMNH Mo185039 in (1) lateral view, (2) dorsal view, (3) magnification of the central margin, showing laminar crystalline imprints, (4) magnification of the cardinal teeth shown in (2). (5), (6) Specimen SMNH Mo185040, (5) lateral view, (6) magnification of lateral surface, showing laminar crystalline imprints. (7) Specimen SMNH Mo185041 in lateral view. (8) Specimen SMNH Mo185042 in lateral view. (9) Specimen SMNH Mo185043. (5), (6), (8) imaged under low vacuum settings. (1), (2), (6)–(9) Scale bars are 200 μm; (3)–(5) scale bars are 100 μm. Claybourn et al. (2019). 

The majority of the fossils found belong to a group called the Helcionelloids, which are widespread in the Early Cambrian Small Shelly fossils, and are of uncertain affinities, having variously been considered to be Gastropods, Monoplacophorans, the Protoconchs of larger shells (the Protoconch is the first part of the shell to form in a marine Mollusc, typically while it is in a planktonic, larval form, so that the growth form of the protoconch is quite different from that of the adult shell), or a separate class of Molluscs, the view that Claybourn et al. take here.

The first of these Helcionelloids recorded from the Shackleton Formation is Davidonia rostrata, a laterally compressed, high shell, that coils through one third of a whirl, with a rugose bands on all but the smallest specimens, which reaches a length of 0.5-1.3 mm and a width of 0.2-0.8 mm, typically being 1.5 times as long as it is high. This species has previously been recorded in Early Cambrian deposits from Anhui Province, China, South Australia, northeast Greenland, New York State, Quebec, and northwestern Spain.

Davidonia rostrata. (6), (7) Specimen SMNH Mo185047, (6) lateral view, (7) dorsal view of supra-apical field; (8)–(11) specimen SMNH Mo185048, (8) magnification of lateral view of parietal train, showing polygonal crystalline imprints on the side surface, (9) dorsal view of supra-apical field, (10) lateral view, (11) magnification of oblique lateral view of supra-apical field, showing polygonal crystalline imprints; (12) specimen SMNH Mo182501 in lateral view; (13) specimen SMNH Mo182502 in lateral view; (14) specimen SMNH Mo182503 in lateral view. (10), (11) Scale bars are 100 μm; all other scale bars are 200 μm. Claybourn et al. (2019).

The second Helcionelloid recorded is thought most likely to be Davidonia corrugata, a high-shelled form with a hooked apex, moderate lateral compression, and broad, flat rugose bands, that reaches 0.5-0.6 mm in length and 0.5-.06 mm in height. This species has previously been recorded from South Australia, although the Australian material showed much more variation in their expansion rate.

Davidonia corrugata. (1)–(3) SpecimenSMNH Mo185044 in (1) oblique lateral view, (2) apical view, (3) magnification of apical region in lateral view, showing protoconch and transition to teleoconch; (4) specimen SMNH Mo185045, oblique view of supra-apical field; (5) specimen SMNH Mo185046 lateral view. (3) Scale bars is 100 μm; all other scale bars are 200 μm. Claybourn et al. (2019).

The third Helcionelloid recorded is thought most likely to be Xianfengella yatesi, a species previously recorded from South Australia and Greenland. The Shackleton material produced a single specimen of this low, cup-shaped shell, measuring 0.9 mm in length, 0.6 mm in width and 0.6 mm in height, and coiling through a third of a whirl. The surface of this specimen has rugose correlations and is covered by polygonal imprints. 

Xianfengella yatesi, specimen SMNH Mo185049, (15) dorsal view, (16) oblique apical view, (17) magnified view of supra-apical field showing crystalline imprints, (18) oblique lateral view. (17) Scale bars is 100 μm; all other scale bars are 200 μm. Claybourn et al. (2019).

The fourth Helcionelloid recorded is placed in the genus Anuliconus, which has previously been recorded in South Australia, but not assigned to a specific species. The thirty-three specimens from Shackleton are 0.4–0.5 mm wide, 0.5–0.7 mm long, and 0.7–0.9 mm high, being high in form and somewhat laterally compressed, with concave lateral areas near their apexes.

Anuliconus sp., (22)–(24) specimen SMNHMo185051, (23) lateral view, (22) magnification of apex in lateral view, (24) apertural view; (25), (26) specimen SMNHMo185052, (25) lateral view, (26) apical view; (27), (28) specimen SMNH Mo185053, (27) lateral view, (28) apical view. (22), (24) Scale bars are 100 μm; all other scale bars are 200 μm. Claybourn et al. (2019). 

The fifth Helcionelloid recorded is tentatively placed in the genus Protowenella, which has previously been recorded in Queensland, the Northern Territory, south China, and Siberia, but not assigned to a specific species. The four poorly preserved specimens assigned to this genus have open coiled shells (shells in which the coils do not touch) that form three quarters of a whirl and measure about 1.5 mm in length and 0.9 mm in height.

Protowenella sp., (19) lateral view, (20) dorsal view, (21) apical view. Scale bars are 200 μm. Claybourn et al. (2019). 

The sixth Helcionelloid recorded is placed in the genus Yochelcionella, which has previously been recorded in New South Wales, north Greenland and Newfoundland, but not assigned to a specific species. The five specimens placed in this genus have flattened shells with an extension from the aperture that appears to form a sort of snorkel.

Yochelcionella sp., (1)–(5) specimen SMNH Mo185063, (1) lateral view, (2) apertural view, (3) apical view of subapical field and broken snorkel, (4) magnified view of concentric structures within snorkel, (5) magnified view of pitted microstructure; (6), (7) specimen SMNH Mo185064, (6) magnification of lateral view, (7) lateral view; (8) specimen SMNH Mo185065, lateral view. All scale bars are 200 μm, except (5) and (6), which are 100 μm. Claybourn et al. (2019). 

The seventh Helcionelloid recorded is placed in the genus Stenotheca, which has previously been recorded in Wales, South Australia and north China, but not assigned to a specific species. The twelve specimens assigned to this genus have flattened shells that coil through one quarter of a whorl, and range from 0.3 to 0.5 mm in length and 0.35 to 0.55 mm in width.

(9)–(16),  (19)–(21) Stenotheca sp. (9), (10) specimen SMNH Mo185066, (9) oblique lateral view, (10) dorsal view; (11)–(13) specimen SMNH Mo185067, (11) oblique lateral view, (12) dorsal view of subapical field, (13) apical view; (14) specimen SMNH Mo185068, lateral view; (15), (16) specimen SMNH Mo185069, (15) oblique lateral view, (16) dorsal view; (19) specimen SMNH Mo185071 in lateral view; (20) specimen SMNH Mo185072 lateral view; (21) specimen SMNH Mo185073 lateral view. All scale bars are 200 μm. Claybourn et al. (2019). 

The final Helcionelloid recorded is placed in the genus Anabarella, and referred to the species, which has previously been recorded from South Australia. The three specimens referred to this species are strongly laterally compressed. And expand rapidly, coiling through less than half a whorl ad they do so.

Anabarella cf. Anabarella australis (17), (18) specimen SMNH Mo185070 in (18) lateral view, (17) apertural view (22) specimen SMNH Mo185074 in lateral view. All scale bars are 200 μm. Claybourn et al. (2019).

The Shackleton Formation material also contains two species assigned to the Family Pelagiellida, considered to be stem-group Gastropods, i.e. organisms more closely related to Gastropods than to any other living group, but which are not descended from the last common ancestor of all living Gastropods, either because they lived before it, or because they form a separate, extinct, branch of the Gastropod family tree.

The fist of these Pelagiellid Gastropods is assigned to the genus Pelagiella, and referred to the species Pelagiella subangulata, which has previously been recorded from South Australia, the Great Basins of America, Germany and south China. About 30 specimens are referred to this species, these being 0.58-0.64 mm in length and 0.38-0.48 mm in height, with rapidly expanding shells that coil dextrally through three quarters of a whorl.

Pelagiella cf. Pelagiella subangulata Tate, 1892, (1–3) specimen SMNH Mo185054, (1) view of spiral side, (2) dorsal view, (3) dorsal view of supra-apical field; (4–6) specimen SMNH Mo185055, (4) apical view, (5) apical view, (6) dorsal view; (7, 8) specimen SMNH Mo185056, with possible hyolith operculum embedded in aperture, (7) oblique apertural view, (8) umbilical side; (9, 10) specimen SMNH Mo185057, (9) lateral view of abapical side, (10) oblique apertural view, showing curved groove passing through the umbilicus; (11, 12) specimen SMNHMo185058, (11) apical view, (12) apertural view; (13–16) specimen SMNH Mo185059, (13) view of supra-apical field, (14) apical view, (15) dorsal view, (16); magnified dorsal view of part of the abapical side on the projecting wing, showing pustulose ornamentation. All scale bars are 200 μm, except (16) which is 100 μm. All images taken using secondary electrons. Claybourn et al. (2019).

The second species of Pelagiellid Gastropod recorded is Xinjispira simplex, a species previously recorded in North China. Twelve specimens of this species are reported, These are globular shells that coil through almost a whorl, and have rounded apertures. They measure 0.5-0.6 mm in length and about 0.4 mm in height.

Xinjispira simplex (17–21) specimen SMNH Mo185060, (17) oblique dorsal view of supra-apical field, (18) lateral view of abapical side, (19) lateral view of apical side, (20) magnification of internal mold with transverse fibrillar crystalline imprints, (21) view of supra-apical field; (22, 23), specimen SMNHMo185061, (22) dorsal view, (23) lateral view of apical side; (24–26) specimen SMNH Mo185062, (24) apical view, (25) maginification of circumbilical channel on apical side, (26) magnification of transverse fibers on supra-apical surface of the steinkern. (20), (24) Scale bars are 100 μm; all other scale bars are 200 μm. All images taken using secondary electrons except (24)–(26) taken using backscattered electrons. Claybourn et al. (2019).

The final Mollusc recorded is Scenella, a Limpet-like fossil accepted as a Mollusc, but of uncertain affinities. Scenella has previously been recorded from British Colombia, Utah, Estonia, and South Australia. Two specimens are recorded from the Shackleton Formation, one of which is broken; the unbroken specimen is 9.8 mm in length and 8.5 mm in width.

Scenella? from the Shackleton Limestone. (1–3) Specimen SMNH Mo185075, (1) oblique view along supra-apical field, (2) lateral view, (3) apical view. (4, 5) Specimen SMNH Mo185076, (4) apical view, (5) lateral view, angled obliquely toward subapical field. Scale bars are 2 mm. Claybourn et al. (2019).

See also...

https://sciencythoughts.blogspot.com/2019/01/tarimspira-artemi-new-species-of.htmlhttps://sciencythoughts.blogspot.com/2018/12/platydoris-guarani-new-species-of.html
https://sciencythoughts.blogspot.com/2018/12/buenellus-chilhoweensis-olenelline.htmlhttps://sciencythoughts.blogspot.com/2018/12/novaculina-myanmarensis-new-species-of.html
https://sciencythoughts.blogspot.com/2018/11/neopilina-sp-tracking-monoplacophorans.htmlhttps://sciencythoughts.blogspot.com/2018/10/pahvantia-hastata-small-filter-feeding.html
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Police seize hundreds of Turtles from traffickers in West Bengal, India.

Four men have been arrested after officers from the West Bengal Criminal Investigation Department stopped a truck in Paschim Bardhaman District on Tuesday 15 January 2019, following a tip off from the Wildlife Crime Control Bureau, and found 689 protected Indian Flapshelled Turtles, Lissemys punctata, in 22 jute sacks in the vehicle. The men had apparently travelled from Sultanpur District in Uttar Pradesh, where the Turtles had been trapped in streams and pools, and were taking them to Kolkata, where they were hoping to sell them, either for consumption locally or for export to Bangladesh of Southeast Asia, where they are also prised as a foodstuff. The Turtles are described as having been very week and distressed, and a number had died due to the conditions they were being kept in. The surviving turtles are being looked after by the Turtle Survival Alliance.

Police and rescue workers with Turtles confiscated from traffickers in West Bengal, India, on 15 January 2018. Turtle Survival Alliance.

Of the 24 species of Freshwater Turtles found in India over half are currently thought to be threatened globally due to Human activities, such as poaching or habitat destruction. The Indian Flapshell Turtle is widespread in South Asia, and not threatened across all of its range, but there is sufficient concern about the species that it has been placed in Appendix II of the Convention on International Trade in Endangered Species (CITES) at the request of Bangladesh, and conservation bodies in India request that people do not post location data publicly when reporting sightings on websites such as the India Biodiversity Portal, for fear that poachers may use the information.

See also...

https://sciencythoughts.blogspot.com/2018/12/basilemys-morrinensis-new-species-of.htmlhttps://sciencythoughts.blogspot.com/2018/11/large-numbers-of-cold-stunned-sea.html
https://sciencythoughts.blogspot.com/2018/11/leatherback-turtle-dies-in-aquarium.htmlhttps://sciencythoughts.blogspot.com/2018/10/sindh-wildlife-department-seizes.html
https://sciencythoughts.blogspot.com/2018/08/kinosternon-vogti-new-species-of-mud.htmlhttps://sciencythoughts.blogspot.com/2018/07/hundreds-of-sea-turtles-washing-up-dead.html
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Dozens dead following pipeline explosion in Hidalgo State, Mexico.

Sixty six people have now been confirmed dead and another seventy six are known to have been injured, following an explosion on an oil pipeline in the town of Tlahuelilpan, in Hidalgo State, Mexico on Friday 18 January 2018. The incident was reportedly caused after thieves drilled into the pipeline in a poor neighbourhood of the city with the intention of stealing oil. This resulted in a rupture on the pipeline, which causes oil to jet into the air. Many people then rushed to the scene hoping to fill containers with some of the oil. An attempt to hold back the crowds was made by military personnel, but it soon became clear that they were badly outnumbered, and they were forced to withdraw. Some time after this the oil was somehow ignited and the area engulfed in a fireball.

The aftermath of a pipeline explosion in Tlahuelilpan, Hidalgo, on Friday 18 January 2019. New York Times.

Thefts of oil from pipelines in Mexico have risen almost ninefold in the last decade, driven by growing economic inequality and rising fuel prices. Incoming president Andrés Manuel López Obrador, who was elected in December, has promised to clamp down on these thefts, deploying military personnel to guard pipelines and shutting down some of the more vulnerable routes completely. However this policy has drawn widespread criticism as it has led to fuel shortages, which appear to have further fed demand for black-market fuel.

Relatives of missing people watching as forensic search teams sift through the aftermath of a pipeline explosion in Tlahuelilpan, Hidalgo, on Friday 18 January 2019. Reuters.

See also...

https://sciencythoughts.blogspot.com/2018/10/propane-gas-truck-swallowed-by-sinkhole.htmlhttps://sciencythoughts.blogspot.com/2018/07/magnitude-57-earthquake-in-oaxaca-state.html
https://sciencythoughts.blogspot.com/2018/06/magnitude-60-earthquake-off-coast-of.htmlhttps://sciencythoughts.blogspot.com/2018/06/seven-dead-in-mexico-flooding.html
https://sciencythoughts.blogspot.com/2018/02/magnitude-72-earthquake-in-oaxaca-state.htmlhttps://sciencythoughts.blogspot.com/2018/02/landslide-destroys-almost-hundred-homes.html
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Diadema setosum: An invasive alien Sea Urchin found on the Mediterranean coast of Israel.

Invasive organisms (organisms introduced to an environment from elsewhere, usually by Human actions) are of concern to environmentalists, as a lack of adapted predators, parasites and pathogens can lead to explosive population booms and subsequent dominance of the new environment. In marine environment Echinoderms (Sea Urchins, Starfish, etc.) are particularly worrying, as their grazing can rapidly deplete habitat forming organisms such as Corals or Seaweads, leading to changes that impact a wide range of other organisms.

The Sea Urchin Diadema setosum is widely distributed in shallow waters in the Indian Ocean and West Pacific. In 2006 a specimen of this Sea Urchin was collected from the Kaş Peninsula in Anatolian Turkey, since when there have been sightings of the species in the Aegean Islands of Greece, and along the coast of the Eastern Mediterranean as far as Lebanon. Since 2016 there have been several reported sightings of Diadema setosum on reefs off the Mediterranean coast of Israel, though an extensive survey by BioBlitz Israel was unable to find any evidence of this.

In a paper published in the journal Zootaxa on 11 October 2018, Omri Bronstein and Andreas Kroh of the Geological-Paleontological Department at the Natural History Museum Vienna report the first confirmed sightings of Diadema setosum on the Mediterranean coast of Israel.

The first evidence presented by Bronstein and Kroh comes from a video made by recreational divers during a night dive at the Gordon Beach site, on the coast of Tel Aviv, on 10 November 2016. This shows a long-spined black Sea Urchin, with a pattern of five white spots, as well as a bright orange ring surrounding the distal margins of the periproctal cone (anus), with white interradial lines connecting the apical disc to the white spots, a pattern considered to be diagnostic of Diadema setosum.

Specimen of Diadema setosum sighted on 10 November 2016 at a depth of 6-8 m off the coast of Tel Aviv, Israel. Adi Gvir in Bronstein & Kroh (2018). 

This sighting prompted a renewed hunt for the species around Gordon Beach by BioBlitz Israel, eventually resulting in the discovery of a single adult specimen in a rock crevice at the Gordon Caves site (near Gordon Beach), from which a single spine was collected.

 
Specimen of Diadema setosum sighted on 17 June 2017 at a depth of 3.5 m off the coast of Tel Aviv, Israel. Bronstein & Kroh (2018).

The spines of all Sea Urchins are covered on scales called verticillations, which come off in any wound caused by the spines, making the injury more painful and unpleasant, and therefore making Sea Urchins less attractive to predators. The verticillations of Diadema setosum are longer and less flared than those of other members of the genus Diadema, another diagnostic feature for the species.

Scanning electron microscope image of Diadema setosum specimen from Gordon Caves, in longitudinal view showing the characteristic diadematoid verticillation. Bronstein & Kroh (2018).

Previous genetic studies of Diadema setosum have suggested that the species is made up of two clades (a clade is a group comprising all the organisms sharing a single common ancestor), which are likely to have split during the Miocene, about 2.5 million years ago. Of these, Clade a is found around much of the margin of Indian Ocean and west Pacific, while Clade b is found around the Arabian Peninsula and from the Red Sea south to Zanzibar. Analysis of the two known Mediterranean specimens (from the Kaş Peninsula and Tel Aviv) shows that these belong to Clade b, supporting the idea that the species has jumped from the Red Sea to the Mediterranean through the Suez Canal.

The genetic analysis also showed that the two specimens were very close to genetically identical, suggesting a very small founder population within the Mediterranean, which has spread slowly around the eastern end of the sea, while maintaining a very low population level, though whether the population will remain stable at such a level in future is uncertain.

See also...

https://sciencythoughts.blogspot.com/2019/01/understanding-how-carbon-from-kelp.htmlhttps://sciencythoughts.blogspot.com/2019/01/acanthaster-solaris-using-environmental.html
https://sciencythoughts.blogspot.com/2019/01/sertulaster-keslingi-and-delicaster.htmlhttps://sciencythoughts.blogspot.com/2018/12/linguaserra-triassica-new-species-of.html
https://sciencythoughts.blogspot.com/2018/03/thousands-of-starfish-wash-up-on.htmlhttps://sciencythoughts.blogspot.com/2016/02/estimating-role-of-temperature-in-sea.html
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Avalanche feared to have killed ten people in the Ladakh Region of Jammu and Kashmir, India.

Five people are known to have died and another five are still missing after an avalanche swept two vehicles from a road in the Ladakh Region of Jammu and Kashmir, India, on Friday 18 January 2019. The incident happened at about 7.00 am local time on the Khardung La Pass, which at 5300 m is one of the highest mountain passes on Earth. The vehicles are reported to have been buried under about six meters of snow, and there is thought to be little chance of finding any survivors. The ten who died are reported to have been employees of the Border Roads Organisation engaged in snow clearing operations on the pass.

Rescue workers at the site of a fatal avalanche on the Khardung La pass in Jammu and Kashmir on 18 January 2019. SNS.

Avalanches are caused by the mechanical failure of snowpacks; essentially when the weight of the snow above a certain point exceeds the carrying capacity of the snow at that point to support its weight. This can happen for two reasons, because more snow falls upslope, causing the weight to rise, or because snow begins to melt downslope, causing the carrying capacity to fall. Avalanches may also be triggered by other events, such as Earthquakes or rockfalls. Contrary to what is often seen in films and on television, avalanches are not usually triggered by loud noises. Because snow forms layers, with each layer typically occurring due to a different snowfall, and having different physical properties, multiple avalanches can occur at the same spot, with the failure of a weaker layer losing to the loss of the snow above it, but other layers below left in place - to potentially fail later.

 Diagrammatic representation of an avalanche, showing how layering of snow contributes to these events. Expedition Earth.

See also...

https://sciencythoughts.blogspot.com/2018/11/landslide-kills-nine-year-old-girl-in.htmlhttps://sciencythoughts.blogspot.com/2018/07/landslide-kills-five-pilgrims-in.html
https://sciencythoughts.blogspot.com/2018/01/swedish-tourist-killed-by-avalanche-in.htmlhttps://sciencythoughts.blogspot.com/2018/01/seven-missing-after-avalanche-in-jammu.html
https://sciencythoughts.blogspot.com/2017/09/magnitude-46-earthquake-in-jammu-and.htmlhttps://sciencythoughts.blogspot.com/2017/04/seven-conformed-deaths-as-heavy-rains.html
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