Monday 31 January 2022

Flooding and landslides kill at least 21 people in São Paulo State, Brazil.

Twenty one people are now known to have died and several more are missing amid heavy rains that have battered the Brazilian state of São Paulo since Friday 28 January 2022. Over 500 000 people have been displaced from their homes by flooding events, and at least 11 to have been killed in a series of landslides triggered by the rains. Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall.

Flooding in the municipality of Franco da Rocha in São Paulo State, Brazil, on Sunday 30 January 2022. CNN.

Southern Brazil has a rainy season that lasts from Ocotober to March, with peak rains from mid-November to mid-January, however, this year's rains have been exceptionally strong. Brazil has suffered a string of flood-related disasters in recent years, most notably in 2011, when over 800 people died. The country has a rapidly growing population, with little effective urban planning, which has led to sprawling urban developments springing up with little thought to natural hazards, and in particular poorer neighbourhoods often expanding up unstable hillsides, with the result that when floods occur (which is not unusual) communities are often quickly overwhelmed. This years exceptional rains have led to more widespread flooding, which may also persist for longer, and there is a distinct danger that without determined action the death toll may exceed that of 2011. Such events are becoming increasingly common in Brazil, something which many climatologists are citing as direct evidence of global warming.

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Sunday 30 January 2022

Magnitude 4.1 Earthquake in San Diego County, California.

The United States Geological Survey recorded a Magnitude 4.1 Earthquake at a depth of about 13.3 km roughly 5 km to the west of the Palomar Observatory in San Diego County, California, slightly after 9.45 am local time (slightly before 5.45 pm GMT) on Sunday 30 January 2022. There are no reports of any damage or injuries relating to this quake, but people have reported feeling it across much of southern California, and in parts of northwest Mexico.

The approximate location of the 30 January 2022 San Diego County Earthquake. USGS.

California is extremely prone to Earthquakes due to the presence of the San Andreas Fault, a tectonic plate margin that effectively bisects the state. The west of California, including Santa Barbara and Los Angeles, is located on the Pacific Plate, and is moving to the northwest. The east of California, including Fresno and Bakersfield is on the North American Plate, and is moving to the southeast. The plates do not move smoothly past one-another, but constantly stick together then break apart as the pressure builds up. This has led to a network of smaller faults that criss-cross the state, so that Earthquakes can effectively occur anywhere.

Tectonic boundaries and faults in California and the surrounding area. USGS.

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

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Scyliorhinus hachijoensis: A new species of Catshark from the Izu Islands of Japan.

Catsharks of the genus Scyliorhinus are small, bottom-dwelling Sharks with distinctive mottled colourations found throughout the temperate and tropical regions of the world's oceans, in areas where the seafloor is less than 500 m deep. They can be distinguished from other Catshark species by the presence of a laterally projected flap on the upper lip margin that covers the lower labial furrow, and the presence of a pelvic apron in males. Two species of Scyliorhinus have been reported from Japan Scyliorhinus torazame and Scyliorhinus tokubee (although Scyliorhinus tokubee may be a junior synonym of Scyliorhinus torazame, which is to say an invalid species name given to members of an already established species). Scyliorhinus torazame is found in waters less than 300 m deep off the coast of Japan from Hokkaido to Okinawa, also occurring in South Korea, the East China Sea, and Taiwan. There have been reports of another, undescribed, species of Scyliorhinus being found off the coasts of the islands of Torishima and Mikurajima in waters 450-500 m deep, and having a distinctive colour pattern not seen in any other described species. Despite reports of this unkown species going back at least three decades, with several specimens being kept at the Shimoda Floating Aquarium in Shizuoka, this species has never been formally investigated or described.

In a paper published in the journal Zootaxa on 20 January 2022, Nanami Ito of the Graduate School of Oceanography at Tokai University, Miho Fujii of the Shimoda Floating Aquarium, and Kenji Nohara and Sho Tanaka, also of the Graduate School of Oceanography and of the School of Marine Science and Technology at Tokai University, formally desctibe the deepwater Catshark from the Izu Islands as a new species of Scyliorhinus.

The new species is named Scyliorhinus hachijoensis, meaning 'from Hachijo' in reference to Hachijojima Island, where most of the specimens found were collected (the suffix 'jima' means 'island' in Japanese, but is widely included in English translations which also use 'island' separately). The species is described from 22 specimens caught off the coasts of Hachijojima, Mikurajima, and Torishima islands, at depths of between 100 m and 650 m.

Scyliorhinus hachijoensis, external morphology. (A), (B) NSMT-P 135960, male, 370 mm TL (off the east coast of Hachijojima Island). (C), (D) NSMT-P 135961, female, 322 mm TL (off the east coast of Hachijojima Island). Panels show (A), (C) dorsal and (B), (D) lateral views of the specimens. Scale bar are 30 mm. Ito et al. (2022).

Scyliorhinus hachijoensis specimens range from 29.4 to 41.9 cm in length, and have a generally tapering body shape. The head is broad and the snout short, the eyes large and slit-like. The spiracles (forward gill slits) are just behind the eyes. The first two gill openings are equal in height, with the remaining three progressively smaller in size. The nostrils are broad, the mouth wide, arched, and short. The teeth are similar on both jaws, with 36-49 teeth in the upper jaw and 32-43 in the lower jaw in the specimens examined. 

The pectoral fins are large and rounded, the pelvic fins broadly triangular. The first dorsal fin is sub-rectangular, the second dorsal fin smaller and more triangular. The anal fin is triangular, the caudal (tail) fin narrow-lobed and asymmetrical, with a developed terminal lobe. The male claspers are long and cylindrical. 

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Saturday 29 January 2022

An Aphidlion preserved in Baltic Amber along with several Aphids.

The term 'Aphidlion' refers to the larvae of some Neuropteran Insects (Lacewings) which are specialised for hunting Aphids. They are related to Antlions, which are also the larvae of Neuropteran Insects, and which hunt Ants, but unlike Antlions, which are ambush specialists, they are free-ranging raptorial predators which actively hunt down their prey. The term Aphidlion is applied to the larvae of two different Neuropteran groups, the Green Lacewings, Chrysopidae, and the Brown Lacewings, Hemerobiidae, which were one thought to be sister groups but are currently thought to be only distantly related within the Neuroptera as a whole (it is also sometimes used for the larvae of Ladybird Beetles, which also feed on Aphids, but this usage for a very different group is confusing, and best avoided). 

Like other Lacewing larvae, Aphidlions are voracious predators with highly specialised feeding apparatus, with the upper and lower jaws fused to form a pair of feeding stylets, which are used to first inject their prey with venom, then digestive juices, and finally to suck out the prey's dissolved tissues. The stylets of Aphidlions tend to be simple and curved, unlike those of Antlions, which bear teeth, or the larvae of Mantis, Bearded, and Lance Lacewings, which have straight stylets. In addition, the body of Aphidlions is rather spindle-shaped compared to other Lacewing larvae.

Their ability to consume large numbers of Aphids in a relatively short period of time makes Aphidlions an important part of modern ecosystems, and has made them attractive to farmers and horticulturalists as a biological means of controlling Aphid populations, with several species used in this way. Aphidlions are also known in the fossil record, as inclusions in Cretaceous and Eocene ambers, although they are not as numerous as adult Lacewings. Based upon the morphology of these fossil Aphidlions, it is assumed that their ecological role is as ancient as the group (Neuropteran Insects formed a major part of Mesozoic ecosystms, ans were formerly far more numerous and diverse than they are today), although this is very hard to prove from isolated individuals.

In a paper published in the journal Palaeobiodiversity and Palaeoenvironments on 25 January 2022, Joachim Haug of the Biocenter and GeoBio-Center at Ludwig-Maximilians-Universität München, Christine Kiesmüller of Cytology and Evolutionary Biology at the University of Greifswald, Gideon Haug, also of the Biocenter at Ludwig-Maximilians-Universität München, Carolin Haug, again of the Biocenter and GeoBio-Center at Ludwig-Maximilians-Universität München, and Marie Hörnig, also of Cytology and Evolutionary Biology at the University of Greifswald, report the discovery of an Aphidlion along with several Aphids in a single piece of Eocene Baltic Amber, strongly supporting the idea that the ecological association between these groups existed by this time.

The amber used in the study was purchased from a dealer, Jonas Damzen, of Vilnius, Lithuania, and now resides in the Palaeo-Evo-Devo Research Group Collection of Arthropods at Ludwig-Maximilians-University of Munich. Baltic ambers predominantly come from the Blue-Earth Formation of Russia's Kaliningrad Peninsula. The age of Baltic Amber is not completely resolved, but most palaeontologists believe it to be of Late Eocene origin, making it between 38 and 34 million years old.

The amber piece described by Haug et al. contains a number of inclusions, including several Insect exuviae (shed skins), all to deformed to be identified, a large elongate Insect, which Haug et al. identify as an Aphidlion, and three smaller Insects with prominent Hemipteran-type beaks, which Haug et al. identify as Aphids.

Specimen PED 0229, Baltic amber. (a) Overview of the entire amber piece. (b) As in (a), colour-marked. (c) Aphidlion in dorso-lateral view. (d) Aphid specimen 1 in dorsal view. (e) Aphid specimen 2 in dorsal view. (f) Aphid specimen 3 in dorsal view. Haug et al. (2022).

Many details on the larger Insect are concealed, but it is elongate, with a distinct head and body, and the head bears three sets of paired structures, iterpreted as antennae, stylets and labial palps. The antennae are elongate and split into three sections, a short wide base, a long, narrow middle section and an tapering tip. The stylets are simple and curved, lacking any teeth, as would be predicted for an Aphidlion. The labial palps have two distinct elements, with the proximal (base) element being obscured and the distal element being club shaped.

Specimen PED 0229, Baltic amber, continued. (a)-(c) Aphidlion. (a) In ventro-lateral view. (b) In (largely) ventral view; note that the head is seen in anterior view. (c) Close-up of head in frontal view (top), same image colour-marked (bottom). (d) Aphid specimen 2 in ventral view. (e) Aphid specimen 3 in ventral view. (f) Aphid specimen 3 in lateral view. (g) Close-up of aphid 2 in lateral view. Abbreviations: at, antenna; hc, head capsule; lp, labial palp; sy, stylet. Haug et al. (2022).

This specimen is too obscured to be identified to species level, but can be identified as an Aphidlion based upon its short antennae, prominent labial palps, and sickle-shaped mandibles. These traits are also found in some Beetle larvae, but these would be expected to have some other features, such as paired maxillary palps, which are absent in the specimen. The general morphology of both the specimen's body and it's appendages also match that of the Aphidlion-larvae of a Brown Lacewing, Hemerobiidae.

The three Aphids are roughly similar in form, but differ in size, with the largest specimen being about 1 mm in length, and the other two only 0.6 mm. The bodies of these specimens are differentiated into heads and trunks, with the heads wider than they are long, and partly covered by the forward part of the trunk. They have prominent antennae protruding antero-laterally from the head, and mouth parts modified to form an elongate beak. The front three segments of the trunk are prominent, each being longer than the head and supporting a pair of 'z' shaped legs. The segments of the posterior part of the trunk are less clearly defined, but there appear to be 9-10, terminating with a compound structure of several segments. 

The similar appearance of the three Aphid specimens suggests that they belong to the same species, with the larger specimen probably being a later instar (developmental stage separated by a moult) than the two smaller specimens. Aphids are very common in Baltic Amber, although it is difficult to differentiate the long winged developmental stages to species level. Based upon the general form of these specimens, Haug et al. suggest that they might belong to the genus Germaraphis.

The amber piece appears to contain the Aphidlion-larvae of a Brown Lacewing, a group which today specialise in predating soft-bodied prey, particularly Aphids. Brown Lacewings are common in the fossil record, and are often found in environments which also support aphids, and preserved larvae are much less common than adults (excluding specimens preserved in amber, most Lacewing fossils are isolated wings, which the larvae lack), and a direct association between these Insects and Aphids in the pasr has been hard to prove. The specimen examined by Haug et al. shows the co-existence of a Brown Lacewing Aphidlion and several Aphids, showing that they were present in the same environment, and therefore that a predator-prey relationship was highly likely, at least as far back as the Eocene.

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Online courses in Palaeontology. 

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Thursday 27 January 2022

Asteroid 2022 BN passes the Earth.

Asteroid 2022 BN passed by the Earth at a distance of about 92 750 km (0.24 times the average distance between the Earth and the Moon, or 0.06% of the distance between the Earth and the Sun), slightly before 2.15 pm GMT on Sunday 23 January 2022. There was no danger of the asteroid hitting us, though were it to do so it would not have presented a significant threat. 2022 BN has an estimated equivalent diameter of 4-12 m (i.e. it is estimated that a spherical object with the same volume would be 4-12 m in diameter), and an object of this size would be expected to explode in an airburst (an explosion caused by superheating from friction with the Earth's atmosphere, which is greater than that caused by simply falling, due to the orbital momentum of the asteroid) between 43 and 30 km above the ground, with only fragmentary material reaching the Earth's surface.

The relative positions of 2022 BN and the Earth on at 2.00 pm on 23 January 2022. JPL Small Body Database.

2022 BN was discovered on 23 January 2022 (the day of its closest approach to the Earth) by the University of Szeged's Szeged Asteroid Program, which is located at the Piszkéstető Mountain Station in the Mátra Mountains to the northeast of Budapest. The designation 2022 BN implies that it was the 13th asteroid (object N - in numbering asteroids the letters A-Y, excluding I, are assigned numbers from 1 to 25, with a number added to the end each time the alphabet is ended so that A = 1, A1 = 26, A2 = 51, etc., which means that N implies the 13th asteroid) discovered in the second half of January 2022 (period 2022 B - the year being split into 24 half-months represented by the letters A-Y, with I being excluded).

The orbit and current position of 2022 BN. The Sky Live 3D Solar System Simulator.

2022 BN has a 872 day (2.39 year) orbital period, with an elliptical orbit tilted at an angle of 2.74° to the plain of the Solar System which takes in to 0.75 AU from the Sun (75% of the distance at which the Earth orbits the Sun) and out to 2.82 AU (282% of the distance at which the Earth orbits the Sun, and 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 Asteroid 2022 BN has occasional close encounters with the Earth, with the most recent having happened in August 2014, and the next predicted for August 2029. The asteroid also has occasional close encounters with the planet Venus, with the last thought to have happened in December 2021.

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