Friday, 16 December 2022

NASA releases dramatic image of Io as Juno Spacecraft begins extended study of the Jovian moon.

NASA has released a dramatic image of Jupiter's moon Io, showing a surface covered by hundreds of active volcanoes, which was taken by the Jovian Infrared Auroral Mapper imager on the Juno Spacecraft on 5 July 2022. The image was taken during a close flyby of the moon, when the spacecraft was about 80 000 km from its surface (for comparison, the International Space Station is 408 km above the Earth's surface, while the Earth's Moon orbit's at an average of 384 300 km).

The volcano-laced surface of Jupiter’s moon Io was captured in infrared by the Juno spacecraft’s Jovian Infrared Auroral Mapper imager as it flew by at a distance of was about 80 000 km on 5 July 2022. Brighter spots indicate higher temperatures in this image. NASA/JPL/Caltech/Southwest Research Institute/Agenzia Spaziale Italiana/Instituto Nazionale di AstroFisica.

Io is the innermost of the four Galilean Moons of Jupiter (the four large moons discovered by Galileo Galilei in January 1610), and is one of the most distinctive bodies in the Solar System, with a surface dominated by a series of extensive volcanic fields. The volcanism is thought to be caused by tidal forces, as Io is pulled by the gravitational forces of both Jupiter and the other large Galilean Moons, deforming and heating the moon's interior. This has led to a body unlike any other in the Outer Solar System, with no significant ice or hydrocarbon deposits (presumably lost due to the heat of the volcanic activity) and a silicate rock surface surrounding an iron or iron-sulphur core.

The release coincides with another flyby of the Jovian Moon, on 15 December 2022, the first of a series of nine close passes, two of them coming within 1500 km of the moon's surface, over the next eighteen months, during which Io will become a focus of research by the Juno Spacecraft. Previous research has shown that the small moon's numerous volcanoes are a significant contributing factor to Jupiter's spectacular polar aurora's, constantly raining charged particles down upon the atmosphere of the planet, which are then swept toward's the poles by Jupiter's powerful magnetic field.

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Tuesday, 13 December 2022

Successful genotyping of two end-Pleistocene, Palaeolithic, individuals from Britain.

The warming period after the Last Glacial Maximum saw radical shifts in the distribution of Animals and Plants in Europe, and with it an expansion of both Human populations and their cultural diversity. However, while the importance of this interval is well understood, we have relatively little evidence from this time.

Improvements in genotyping ancient remains have enabled scientists to study ever older populations in recent years, with the ability now including individuals from the Late Pleistocene of Europe. Such studied have exposed shifts in genetic patterns within populations, exposing Human migrations that were not clear from the conventional archaeological record. One of the more notable of these newly discovered population shifts occurred between the Last Glacial Maximum, approximately 23 000 years ago, and the onset of the Holocene Epoch, which is placed at 11 700 years before the present. During this shift, populations belonging the 'Goyet Q2' ancestry group, named after the 15 090-year-old Goyet Q2 individual from Belgium were replaced with populations belonging to the 'Villabruna' ancestry group, named after the approximately 14 010-year-old Villabruna individual from Italy. 

The Goyet Q2 ancestry group has been shown to include the roughly 18 700-year-old El Mirón individual from Spain, as well as other individuals associated with the ancient Magdalenian Culture, which is found at archaeological sites dated to between about 20 500 years ago and about 14 000 years ago across Europe. It has been suggested that this group represents individuals descended from a population from a southwest European glacial refugia, which spread across Europe as the glaciers covering the continent retreated.

The Villabruna ancestry group, also known as the Western Hunter Gatherers, includes a range of individuals found across Europe, dating to between about 14 000 and about 7000 years ago. This genotype group has been associated with individuals from archaeological sites associated with Epigravettian, Azilian/Federmesser, Epipalaeolithic and Mesolithic cultures. While this ancestry group is considered to be entirely European in distribution, all of the individuals assigned to it also show genetic affinities to modern Near Eastern populations. The expansion of this population has been linked to the onset of the rapid warming phase known as the Late Glacial Interstadial, about 14 650 years ago, as well as the cultural transition that saw the Magdalenian/Late Upper Palaeolithic culture replaced by the Azilian/Federmesser-Gruppen/Final Palaeolithic culture, and has been suggested to have been linked to a new group of people migrating into Europe during this warming phase.

Curiously, individuals of mixed Goyet Q2/Villabruna ancestry are also known from southern Europe, first appearing about 18 700 years ago, with the El Mirón individual. This has led to the suggestion that European Humans were confined to a few isolated refugia in the southern part of the continent during the Last Glacial Maximum, but that there was some genetic and cultural exchange between these refugia. However, the fact that people with unadmixed Goyet Q2 genotypes were living in Europe as late as 14 000 years ago suggests that this interchange was very limited, and that high levels of isolation persisted through the Last Glacial Maximum and into the Late Glacial. 

There is also evidence of people living north of the Alps during the Last Glacial Maximum, migrating from east to west, and remaining in ice-marginal environments. These people have been linked to the Magdalenian culture, which would fit with the model of the Goyet Q2 ancestry group being Magdalenian hunter gatherers, who retreated into northern Europe as the climate warmed, possibly following herds of Reindeer or Horses. South of the Alps, species such as Red Deer persisted throughout the Last Glacial Maximum and Late Glacial, creating a wider range of ecological opportunities for Human hunter gatherers, and thereby allowing greater population admixture in this region. 

The northwesternmost limit of this post-glacial expansion reached Britain, of which two thirds were covered with ice during the Last Glacial Maximum. Britain deglaciated rapidly, leading to accelerated ecological and environmental changes. By 19 000 years ago the ice sheet which had covered much of Britain and Ireland was melting rapidly, with England and Wales being free of ice by about 16 000 years ago. Reindeer are known to have been present in southwest England by 17 000 years ago, living in a landscape dominated by open steppe–tundra vegetation. The earliest evidence for Human occupation in post-glacial Britain comes from about 15 500 years ago, with populations probably established in several areas by the onset of the Late Glacial Interstadial, 14 650 years ago. Current dating suggests that Britain was repopulated after the nearby Paris Basin and the Belgian Ardennes, possibly by people expanding from those regions. The Magdalenian toolset used by these earliest colonisers was similar to that used in the northern Netherlands and the lowlands of northern Germany and Poland. Nevertheless, the amount of archaeological material we have from Britain during this period is extremely limited, restricting the the inferences that can be made about this population.

Genetic analysis techniques have been applied to Mesolithic, Neolithic, and Bronze Age individuals from Britain, but not, to date, to individuals from the Palaeolithic. This is, at least in part, due to the extremely limited nature of the Palaeolithic skeletal record, with such material only having been recovered from only six sites across Britain. The position of this population, at the extreme fringe of the post-Late Glacial Maximum European expansion, means that they can potentially tell us a great deal about the movement of Human populations during this time. All Mesolithic British individuals genotyped to date have belonged to the Villabrauna population, suggesting that this group had reached the northwesternment fringe of Europe by about 10 500 years ago. It is not clear, however, just when these people arrived in Britain, or what the genetic affinities of the Palaeolithic populations of Britain were. The apparent link between the Goyet 2 ancestry group and the Magdalenian culture leads to the hypothesis that these earliest settlers in Britain belonged to that group, but this has not, to date, been tested.

In a paper published in the journal Nature Ecology and Evolution on 24 October 2022, a team of scientists led by Sophy Charlton of the School of Archaeology at the University of Oxford and the Natural History MuseumSelina Brace, also of the Natural History Museum, and Mateja Hajdinjak of the Ancient Genomics Laboratory a the Francis Crick Institute, present the results of analysis of the DNA of two individuals from the Late Palaeolithic of England and Wales, and discuss the implications of their results. 

The first individual included in the study came from Kendrick’s Cave, which is located on Great Orme’s Head, a limestone massif in Llandudno, North Wales. This cave yielded four individuals, three adults and a child, which have been radiocarbon dated to between 11 990 and 11 905 years before the present. As well as the Human remains, the site yielded a range of artefacts which have been linked to the Magdalenian culture, including the proximal portion of a broken blade with en éperon butt preparation, a cut-marked Bovine bone dated to about 14 500 years before the present, a decorated Horse mandible dated to about 12 900 years before the present, and beads made from the teeth of Brown Bear,  Aurochs and Red Deer. 

The first molar from the mandible of the one individual (Kendricks_074, the skeleton dated to 11 905 years before the present) from Kendrick's Cave was subjected to DNA analysis. In addition, samples a were taken from all four Kendrick's Cave skeletons for  carbon and nitrogen isotope analysis. This isotopic analysis provided insight into the diet of the individuals, which suggested a diet rich resources obtained from marine or freshwater sources. This is known to have an impact on radiocarbon dating, leading to a revised date for Kendricks_074 of 13 770 to 13 390 years before the present, and a revised occupancy period for the cave, starting between 16 410 and 14 070 years before the present, and ending between 13 730 and 13 140 years ago. 

The second individual included in the study comes from Gough’s Cave, part of a large cave system situated in Cheddar Gorge in Somerset, southwest England. Gough's Cave is one of the best known Palaeolithic sites in Britain, with a large assemblage of both stone tools and Animal remains. Occupancy at the site is thought to have begun at the beginning of the Late Glacial Interstadial, as temperatures in the region began to rise rapidly. The technology present comprises a mixture of late Magdalenian and early Federmesser-Gruppen tools. At least six Palaeolithic Humans were buried here (one child, two adolescents, and three adults), as well as a later, Mesolithic individual (famous as 'Cheddar Man'). Two of the Palaeolithic Humans have been directly radiocarbon dated, and all show signs of considerable postmortem modification, interpreted as signs of cannibalism, and the modification of skulls to manufacture drinking cups. Based upon the radiocarbon dates obtained and the technologies present in the cave, the Palaeolithic occupation of Gough's Cave is thought to have lasted from about 14 840 to about 14 680 years ago - less than 200 years.

One of the human skulls carefully shaped into a cup or bowl by the people who lived at Gough's Cave 14,700 years ago. Natural History Museum.

Charlton et al. obtained sample DNA from a Human temporal bone (PVM 96544) from Gough's Cave, as well as carrying out new radiocarbon dating on this and other material from the site. The new radiocarbon data was used to obtain a revised occupation period for the cave, starting between 15 070 and 14 850 years ago, and ending between 14 960 and 14 610 years ago. This new dating suggests that occupation began before the onset of the Late Glacial Interstadial warming.

None of the Human material from Gough's and Kendrick's caves shows overlapping dates. However, the modified Bovid bone from Kendrick's Cave does overlap chronologically with the Human remains from Gough's Cave, suggesting that both sites were occupied simultaneously for at least some of the period. The two individuals included in the study were separated in time by at least 600 years (assuming no seafood was consumed in either party's diet), but this could potentially be as high as 840-1200 years.

Charlton et al. recovered 15 497 unique fragments of mitochondrial DNA and 30 587 614 unique fragments of nuclear DNA from the Gough's Cave individual, representing about 23% of the total genome. From the Kendrick's Cave individual they recovered 9702 unique fragments of mitochondrial DNA, and 29 326 159 unique fragments of nuclear DNA, representing about 18% of the total genome. 

ecause mitochondrial DNA is found in the mitochondria, organelles outside the cell nucleus, it is passed directly from mother to child without being sexually recombined each generation, enabling precise estimations of when individuals shared common ancestors, at least through the female line, forming a mitochondrial haplogroup. It is also possible to trace direct ancestry through the male line, using DNA from the Y chromosome, which is passed directly from father to son without sexual recombination, forming a Y-chromosome haplogroup.

The mitochondrial DNA recovered was sufficient to assign both individuals to mitochondrial haplogroups. The Gough's Cave individual belongs to the U8a haplogroup, while the Kendrick's Cave individual belongs to the U5a2 haplogroup. The U8a haplogroup has not been previously recorded in Britain, but is the haplogroup to which the Goyet Q2 individual belongs, as well as individuals associated with Magdalenian artefacts at several archaeological sites, including those at Hohle Fels and Brillenhöhle in Germany. The U5 haplogroup has been recorded at several Mesolithic sites in Britain, including one from Kent's Cavern who shares the U5a2 haplogroup variant. 

It was also possible to determine the sex of both individuals, with the Gough's Cave individual being female, and the Kendrick's Cave individual being male. Interestingly, the Kendrick's Cave individual had been recorded as 'male' in the original description of the skeleton, although no reason was ever given for this.

The nuclear genome of the Gough's Cave individual is close to that of the Goyet Q2 individual, placing that individual within the Goyet Q2 ancestry group. The Kendrick's Cave individual clusters with individuals from the Villabrauna ancestry group, including Mesolithic individuals from Britain; to date all Mesolithic individuals from Britain have belonged exclusively to the Villabrauna ancestry group, with the exception of 'Cheddar Man' (who was also recovered from Gough's Cave), who's ancestry was 84.6% Villabrauna and 15.4% Goyet Q2.

Location, genetic ancestry and Accelerator Mass Spectrometry date of End Palaeolithic European individuals. (a) Map indicating the location of Pleistocene sites and the genetic ancestry of individuals analysed from them. (b) North Greenland Ice Core Project ice core δ¹⁸O values and event stratigraphy, genetic ancestry and date  of individuals (95% confidence interval of calibrated radiocarbon dates for directly dated Humans). The Gough’s Cave and Höhle Fels specimens are not directly dated and therefore for Höhle Fels specimen the age range shown is the 95% confidence interval of calibrated radiocarbon dates from bones recovered from the same area/context. For the Gough’s Cave specimen, the age range shown is the Bayesian modelled site occupation start and end dates based on Accelerator Mass Spectrometry dating of the Human remains and Human modified faunal remains. Charlton et al. (2022).

The genetic and radiocarbon dating evidence obtained by Charlton et al. indicates that two genetically distinct populations of Humans were present in Britain during the Late Glacial period. The individual sampled from Gough's Cave showed clear affinity to the Goyet Q2 ancestry group, while the Kendrick's Cave individual clearly grouped with the Villabrauna group. Neither individual showed any genetic admixture, although the Gough's Cave tool assemblage does appear to be of mixed origins, containing both late Magdalenian and early Federmesser-Gruppen technologies. Furthermore, the only lithic tool from Kendrick's Cave clearly fits with the Magdalenian technology, while the individual sampled from the same location belonged to the Villabrauna ancestry group, typically associated with the Epigravettian and Azilian/Federmesser technologies. However, the decorative objects from Kendrick's Cave are similar to items from Federmesser-Gruppen sites in Europe. This may indicate that the boundaries between cultures were not so rigid at this time as generally assumed, or even that the populations at both sites contained a mixture of Humans from both cultures, but this has not been captured by sampling only one individual from each group. What the study does clearly demonstrate is that the Villabrauna ancestry group had clearly reached Britain by the Late Glacial, though whether there is a continuity with Holocene populations belonging to the same group, or whether they represent a subsequent second migration to the island after the Younger Dryas cooling event (between 12 900 and 11 700 years ago) is unclear.

The Younger Dryas represents a significant interlude between the temperate climate of the Late Glacial and that of the Holocene. During this interval ice sheets spread southward from Scotland, and Reindeer become the most common Animal remains found in caves in southwest Britain. At the moment, there are no Human remains from Britain which can be assigned to the Younger Dryas interval by radiocarbon dating, though it is unclear if this represents a lack of (discovered) preserved material or an actual absence of Humans. If there really were no Humans present in Britain during this period, then the subsequent Villabrauna populations must represent a second migration of that group into Britain. Furthermore, whilst the Villabrauna ancestry group appears to be dominant in Britain during the Mesolithic, at least one individual is known to be of mixed heritage, possibly suggesting that the cultural changes that led to the Mesolithic involved a degree of blending between groups.

Britain is not the only area where both Late Palaeolithic European populations are present, the same has been observed in Iberia, where individuals with mixed heritage are present at El Mirón in Spain from about 18 770 years ago. However, while both populations have been detected in Britain, no trace of genetic admixture has (yet) been discovered in the Palaeolithic, which may indicate a more dramatic population turnover.

These two Late Palaeolithic populations from Britain lived somewhere between 600 and 12 000 years apart, and, as well as being genetically different, appear to have had different diets, based upon stable isotope analysis of skeletal material from the two sites. They also appear to have had quite different approaches to the handling of the dead, with modification of remains and possible cannibalism present at Gough's Cave but not at Kendrick's Cave. This does suggest that a considerable degree of cultural, as well as genetic, turnover was occurring during a time of known climatic and ecological shifts, again, something seen elsewhere in Europe.

The very limited supply of skeletal material from the Late Pleistocene of Britain, along with the rate at which DNA degrades in deceased individuals, means that there will never be a very clear picture of the genetic make-up of these populations. However, a limited amount of information is not zero, and Charlton et al. have demonstrated that useful studies can be done on Late Pleistocene genetics in Britain, raising the potential that we yet learn more about this subject.

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Friday, 9 December 2022

Eresus da & Eresus yukuni: Two new species of Velvet Spider from Xinjiang Province, China.

Velvet Spiders, Eresidae, are a group of highly distinctive Spiders with an almost exclusively Old World distribution (a single species is known from Brazil). They are often brightly coloured (some species are known as Ladybird Spiders for this reason) and typically live within underground tubes lined with silk, acting as ambush predators in areas with low vegetation, and well drained soil. Unusually for Spiders, some species are social, living in large colonies which co-operate in the raising of young. Parental care is a one of the distinguishing features of Velvet Spiders, with the females actively feeding their young for some time after hatching, liquefying their own internal organs in order to do so. The bright colours and distinctive behaviour of Velvet Spiders, combined with a preference for land also favoured by Human farmers, has led to many species having protected status.

In a paper published in the Biodiversity Data Journal on 6 December 2022, Yejie Lin of the Hebei Key Laboratory of Animal Diversity at Langfang Normal University, Shuqiang Li of the Institute of Zoology of the Chinese Academy of Sciences, Xin Zhao and Zhanqi Chen of the Key Laboratory of Tropical Forest Ecology at the Xishuangbanna Tropical Botanical Garden, and Haifeng Chen, also of the Hebei Key Laboratory of Animal Diversity at Langfang Normal University, describe two new species of Velvet Spider from Xinjiang Province, China.

Both new species are placed in the genus Eresus, which gives its name to the group and which contains 24 of the 102 currently described Velvet Spider species.

The first new species described is named Eresus da, where 'da' is a Chinese word meaning 'large', in reference to the large size of the species, the carapace of which can reach over 10 mm in length. Only a single female specimen of this species were observed, this being dark brown in colour, except for the carapace which is a lighter, reddish brown, and the white spots on the abdomen, the whole body being covered by short, white hairs.

Eresus da, holotype female. (A) Dorsal view. (B) lateral view. Lin et al. (2022).

The single known specimen of Eresus da was found living in a silk tunnel about 20 cm in length sheltered behind a clump of desert plants, and connected to an underground nest. The entrance to the tunnel was surrounded by the empty exoskeletons of desert Beetles, which appear to be the main prey of this species.

Eresus da, holotype female. (A) habitat; (B) microhabitat; (C) tunnel wrapped with Beetle exoskeletons; (D) Beetle skeletons (Pimeliinae sp.); (E) Spider with nest. Lin et al. (2022).

The second new species is named Ersus yukuni, in honour of Yu Kun, who collected the single known specimen of the species, a male. The specimen is black in colour, and covered by a dense layer of black and white hairs. 

Eresus kukuni, holotype male. (C) Dorsal view. (D) lateral view. Lin et al. (2022).

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Wednesday, 7 December 2022

Fossil eggshells from the Early Cretaceous Okurodani Formation of Gifu Prefecture, Japan.

The past three decades have seen the discovery of a large quantity of fossil eggs from several Lower Cretaceous deposits in Japan, notably the Yezo Group of Hokkaido, the Kuwajima Formation of Ishikawa Prefecture, and the Ohyamashimo Formation in Hyōgo Prefecture. These include eggs which are thought to have come from Ornithopod and Theropod Dinosaurs (including Oviraptosaurs, Troodontids, and Birds). These findings add to the known palaeobiodiversity of these areas, by indicating the presence of groups not known from the skeltal fossil record. However, the majority are of Aptian or Albian age (121.4-100.5 million years old), with earlier examples being much rarer.

The Okurodani Formation outcrops in the Shokawa area of northwestern Gifu Prefecture, and is considered to be of Hauterivian age (i.e. between 132.9 and 129.4 million years old). This formation has produced a variety of Vertebrate remains, including Dinosaurs, aquatic Tetrapods and Fish, as well as a number of fragmentary egg pieces, which have been assumed to have been of Dinosaurian origin, but never formally investigated.

In a paper published in the journal Historical Biology on 24 November 2022, Rina Uematsu of the Graduate School of Science and Technology at the University of TsukubaKohei Tanaka of the Faculty of Life and Environmental Sciences at the University of Tsukuba, Shohei Kozu of the Gifu Prefectural Museum, Shinji Isaji of the Natural History Museum and Institute of Chiba, and Shizuo Shimojima of Takayama City, describe the known egg material from the Okurodani Formation, and discuss the implications this has for the known biodiversity of the environment which produced these strata.

All the fossils examined in the study were collected between 1988 and 2009 by Shizuo Shimojima, Masatoshi Okura and Satoru Sakamoto, from the Okurodani Formation, a 220 m thick sequence of shale, alternating sandstone and mudstone, and sandstone beds, which forms part of the Itoshiro Subgroup of the Middle Jurassic to Lower Cretaceous Tetori Group, which has been dated to between 133 and 129 million years old, based upon uranium-lead dates obtained from layers of volcanic tuff within the formation.

Map of the eggshell locality. (A) Distribution of the Tetori Group in Japan formed of three subgroups. (B) Stratigraphic position of the Okurodani Formation in the Shokawa area. (C) Detail of the boxed area in (A), showing the distribution and the stratigraphic sequence of the Okurodani Formation with the locations where eggshell materials were collected. GPM-Fo-1923, 09/Cr/89/01 and 09/Cr/88/07 were found in debris of fallen rocks and their location is not specified in the stratigraphy. Uematsu et al. (2022).

Sevem fragments of eggshell and two eggshell impressions were found within black mudstone layers within the Okurodani Formation. These mudstone layers are also rich in Plant fossils and freshwater Molluscs, and are interpretted as having been laid down in a network of stagnant pools or oxbow lakes within a floodplain environment. Vertebrate remains, predominantly Fish scales and Turtle shells, but also including Frogs, small Lizards, and Choristoderes (Crocodile-like Diapsids of uncertain affinities) are typically preserved in three dimensions (i.e. not compressed),  which implies rapid burial with minimal movement. Dinosaur fossils are rare in these layers, but the teeth of Ornithopods, Sauropods, and Verociraptorines have been found, as well as the tarsometatarsus of an Enantiornithine Bird.

The first two eggshell fragments discussed, GPM-Fo-1923 and 09/Cr/89/01, are assigned to the Oofamily Testudoolithidae (i.e. Turtle Eggs). These fragments are approximately 5 x 6 mm and 3 x 3 mm, respectively, and are assumed to have come from the same egg, based upon cross-sections of the joint and the overall  shape of the fragments when jointed. However their precise origin is unclear, because they were collected by Masatoshi Okura, who has since passed away, and are now housed in separate museums. The outer surfaces of both shells are strongly abraded and show nodular patterns composed of tightly packed shell units. Based upon the curvature of the eggshell, the original egg would have been about 22 mm in diameter.

Eggshell assigned to Testudoolithidae. (GPM-Fo-1923). (A) Nodular outer surface with exposed shell units. (B) Radial thin section under normal light, showing discrete shell units (bracket), tubular pore canals (white arrowheads) and cratered bases (black arrowhead). The shell appears two-layered with an undulating boundary (arrow). (C) The same view as (B) under polarised light, exhibiting irregular extinction patterns. (D) Radial view, scanning electron microscope, showing discrete shell units (bracket) with ill-preserved ultrastructure. Uematsu et al. (2022).

These shells show two separate layers, separated by an undulating horizontal boundary. In the upper layer, needle-like crystals radiate outward from the boundary. Although less prominent, such acicular crystals are also found in the lower layer; the crystals develop concentrically from the organic cores, making the basal parts of the shell units rounded in shape. Under polarised light, the eggshell exhibits irregular extinction patterns. 

Turtle eggs typically have only a single layer, so the structure of the these eggshells, with two distinct layers, each with a different type of crystals, is distinctly unTestudine. Apparently double-layered Turtle eggshells can be produced taphonomically, by when two shell fragments happen to come to rest with one sitting inside the other, or as a result of a pathology - gravid female Turtles, suffering from some king of environmental stress, can retain eggs instead of laying them, depositing additional layers of minerals on the surface of the egg during the process. Neither of these appears to be the case in this instance, rather the eggs appear to have been altered diagenetically, with the outer portion of the shell having been recrystalised as a result of contact with external chemistry.

Based upon the morphology of these eggshell fragments, it is estimated that they were laid by a small Cryptodiran Turtle, with a carapace length of less than 200 mm.

The next five specimens, GPM-Fo-1294, 1295, 1296, 1297, and 1298 are placed within the Oofamily Prismatoolithidae, which is typified by a two-layered structure and an ornamented shell surface. They are assigned to a new oospecies, with GPM-Fo-1925 as the holotype, and given the name Ramoprismatoolithus okurai, where 'Ramoprismatoolithus' derives from 'Ramo-' from the Latin 'ramus', meaning branch, plus '-prismatoolithus', from the oofamily name, in reference to the reticulate ridges on the other surface of the eggshell, and 'okurai', honours the late Masatoshi Okura who pioneered the discovery of fossil eggshells and other Vertebrate remains in Shokawa.

All of these specimens are fragmentary; no intact examples of this new oospecies are known. The outer surface of these shells is distinctly sculpted, with low ridges arranged in elaborate reticulated patterns. The shells range from 0.31 to 0.61 mm in thickness, with the average being 0.46 mm. Seen under a scanning electron microscope, a near-vertical, unbranching, pore canal could be observed, increasing slightly in width towards the surface of the egg.

Ramoprismatoolithus. (A), (B) Eggshell outer surfaces showing the well-sculpted reticulation: (A) holotype: GPM-Fo-1925 and (B) a cast of GPM-Fo-1924 made of  silicone rubber. (C) Radial thin section under normal light, showing a mammillary layer (ML) and a prismatic layer (PL) with a gradual boundary (horizontal bar on the left side) (holotype: GPM-Fo-1925). (D) the same view as (C) under PLM, showing columnar extinction patterns. (E)–(G) Radial view under Scanning Electron Microscope (holotype: GPM-Fo-1925), displaying (E) ML and PL, (F) numerous vesicles (arrowhead) over the eggshell and (G) acicular crystals at the base of mammillae. (H) Straight pore canal under Scanning Electron Microscope (GPM￾Fo-1928). Uematsu et al. (2022).

These eggshells show two layers, which appears to be an original feature rather than something produced by diagenetic alteration, with a lower mammillary layer (the inner layer of many eggs, which is made up of small calcium carbonate crystals, which are easily disolved and provide a source of calcium for the growing embryo) and the upper prismatic layer (made up of larger crystals, which provides structural strength to the egg) observable. These are separated by a gradual boundary. The mammillary layer makes up about one fifth to one sixth of the shell's thickness, and is comprised of  acicular crystals radiating from what were presumably organic cores. The base of this layer is abraded, probably due to absorption of calcium by the growing embryo. The prismatic layer is made up of narrow, columnular crystals, visible under polarised light. Vesicles can be seen in this layer under the scanning electron microscope.

Based upon the thickness of the shell fragments, the original Ramoprismatoolithus okurai eggs are calculated to have had an average mass of 99.39 g, which assuming an egg twice as long as it is wide, would give an original size of about 57 x 133 mm.

Prismatoolithid eggs are generally accepted to have been laid by Troodontid Dinosaurs, as intact eggs assigned to the oofamily have been found with Troodontid embryos inside. However, it has been suggested that some eggs assigned to this oofamily might have been laid by early Birds.

The small estimated size of the Ramoprismatoolithus okurai eggs leads Uematsu et al. to conclude the Animal which laid them weighed somewhere between twelve and seventeen kilograms, small for a Theropod Dinosaur, but not implausible for a non-Avian Maniraptoran.

The final two specimens described are GPM-Fo-1929, an impression of part of an outer eggshell surface measuring 6 × 7 mm, and 09/Cr/88/07, a possible impression of part of an inner eggshell surface, measuring 2 x 2 mm. Neither of these specimens preserves any of the original eggshell material. The outer surface impression GPM-Fo-1929 bears a strong resemblance to the outer surface of the Ramoprismatoolithus okurai egg fragments, with reticulate ornamentation and the remains of several pore openings. The inner shell fragment impression, 09/Cr/88/07, is smooth, with no discerning features which would allow it to be associated with any known egg fossil.

Indeterminate eggshell impressions. (A) Outer surface impression (GPM-Fo-1929). (B) Cast of (A) made of silicone rubber, showing reticulate ornamentation similar to Ramoprismatoolithus and remains of pore openings (arrowheads) between the ridges. (C) Inner? surface impression with a smooth appearance (09/Cr/88/07). Uematsu et al. (2022).

The specimens described by Uematsu et al. are the oldest known fossil eggshells from Japan, and provide additional information on biodiversity within the Early Cretaceous Tetori Group, within which skeletal material is scarce, demonstrating that Turtles and small Dinosaurs were nesting in the area. 

The eggs assigned to Ramoprismatoolithus okurai are likely to have been laid by a Troodontid, or closely related Maniraptoran Theropod. Okurodani Formation yields teeth of possible Velociraptorinae, and other strata within the Tetori Group (likely to be roughly co-eval, but laid down in different environments within the same landscape) have produced possible Oviraptorosauria and Dromaeosauridae, as well as the Therizinosaur-related Fukuivenator paradoxus. However, all of these groups are known to produce non-prismatic shells with microstructures unlike that of the Oofamily Prismatoolithidae. This strongly suggests that the Ramoprismatoolithus okurai eggs were produced by a small Maniraptoran Theropod not represented in the skeletal fossil record of the Tetori Group. 

Troodontids, and basal Paravians (the group that includes Troodontids, Birds, and Dromaeosaurs) in general are scarce in Early Cretaceous deposits, both as skeletal and egg remains. Examples are known from the US, Spain, and China, and all Early Cretaceous small non-Avian Theropods known from East Asia come from two formations in northeastern China, the Yixian and Huajiying. Thus the discovery of the Ramoprismatoolithus okurai eggs in Japan is a significant contribution to our understanding of the distribution of mall non-Avian Theropods from the early Early Cretaceous of East Asia.

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Saturday, 3 December 2022

New investigations at Holly Shelter, KwaZulu-Natal, South Africa.

South Africa is considered to be a key area for the understanding of the history both of Hominins as a group and Modern Humans as a species. Despite this importance, only a limited number of sites attributed to the Middle Stone Age, an important developmental stage for Modern Humans, have been excavated within South Africa, and only six from KwaZulu Natal. The Holly Shelter site on Fountainhill Estate near Wartburg is one of only two such rockshelters in KwaZulu-Natal which are not located in coastal areas, the other being Border Cave, on the western scarp of the Lebombo Mountains. 

Holly Shelter was first investigated by archaeologist Gordon Cramb in the 1950s. The site produced both organic material and stone tools, a combination with the potential to yield a great deal of information about the period using modern techniques unavailable in Cramb's time. Recent re-examination of Cramb's material has suggested that it is similar to the assemblage recovered from Sibhudu Cave, about 40 km to the north of Durban, which would make the material likely to be 50-60 thousand years old, although the site itself has not been dated. 

In a paper published in the South African Journal of Science on 30 November 2022, Gregor Bader of the Senckenberg Centre for Human Evolution and Palaeoenvironment at the University of Tübingen, and Manuel Will of the Department of Early Prehistory and  Quaternary Ecology, also at the University of Tübingen, present the preliminary results of a new investigation at Holly Shelter, which aimed to establish whether there are any intact archaeological deposits left at the site, whether the site features a discernible stratigraphic sequence which can be dated, is there any useful preservation of organic remains at the site, and whether distinct techno/typological units can be identified within the stratigraphic sequence.

(a) Location of Holley Shelter and other archaeological and palaeoenvironmental sites mentioned in the text.  (b) Three-dimensional model of the site produced with Agisoft Metashape Professional. Gregor Bader in Bader & Will (2022).

In the early 1950s Gordon Cramb excavated two areas close to the entrance of Holly Shelter, uncovering two distinct layers of occupation, the upper one producing a Later Stone Age technology, and the lower a Middle Stone Age technology, including bone tools. Bader and Will refrained from carrying out excavations close to this area, as there are now several large rock slabs lying on the surface here. Cramb's later investigations concentrated on an are further north, and deeper within the cave, an area which Bader and Will also concentrated on, as it was clear of large surface debris, and appeared more likely to yield a full stratigraphic sequence, excavating two new test trenches.

Excavation plan of Holley Shelter. Cramb Exc. 1 and 2 mark the areas of Cramb’s excavations in the 1950s. Exc. 1 was described by Cramb as the ‘Smaller habitable area’, Exc. 2 as the ‘Larger habitable area’. Green squares were excavated in 2022. Gregor Bader in Bader & Will (2022).

Both of Bader and Will's new trenches confirmed the existence of layered archaeological remains. The northern trench produced an upper layer of disturbed soil 5-10 cm thick, beneath which was a layer of orange-brown sandy silt, with charcoal inclusions. This layer contained several small hearths (former fire sites) as well as Middle Stone Age stone artefacts, predominantly made from hornfells, and a significant amount of faunal remains. Beneath this was a grey sandy silt layer. At the southern site this grey sandy silt produced a large hearth which covered most of the excavated area, as well as a large number of stone artefacts, including numerous splintered pieces similar to the ones identified in the Cramb collection, unifacial points, and frequent blades and points with faceted platforms. This layer also produced a lot of faunal remains, along with large charcoal fragments and Plant fossils. In both layers the finds were concentrated at the hearth sites, with little material in the surrounding area.

(a) West-profile of the northern section with layers redrawn, (b) west-profile of the northern section (original), and (c) three-dimensional model of the northern section at the end of the 2022 excavation season. Gregor Bader in Bader & Will (2022).

The lithic assemblage recovered by Cramb contained a high proportion of modified tools compared to debitage (flakes). This was previously assumed to be bias on the part of the mid-twentieth century archaeologist, who was operating at a time when the importance of small flakes was less well understood, and these were commonly overlooked. However, Bader and Will's assemblage contains a similarly high proportion of large tools, with  splintered pieces and unifacial points being the most common items in both collections. 

Artefacts from the lower layer in the northern section at Holley Shelter: (a)–(c) unifacial points, (d)–(f) splintered pieces, (g), (h), (k), (m), (n), (o) identifiable faunal remains, (i), (j) bone flakes, (l), (p) bones with cutmarks. Gregor Bader in Bader & Will (2022).

Bader and Will's excavations revealed a clear stratigraphic sequence at Holley Shelter, with archaeological evidence including material excellent organic preservation and clearly delineated anthropogenic hearth features. The sedimentology of the tool-bearing layers clearly matches Cramb's original description, as does that of the underlying layers, providing support for the accuracy of Cramb's descriptions.

The low proportion of debitage to finished tools, particularly when compared to assemblages from coastal sites in KwaZulu-Natal, suggests that the tools were not being manufactured on site, and the combination of these with the presence of multiple small hearth features, suggests that the site was repeatedly used as a location for short stays, while the coastal sites were likely to be more permanent settlements.

Bader and Will uncovered numerous pieces of charcoal from both artefact-producing layers at Holley Shelter, which opens the potential to establish a timeline for the site based upon radiocarbon dating. The excellent preservation of much of the organic material recovered from the site also has the potential to reveal much about the climate and ecology of the interior of KwaZulu-Natal during the Late Pleistocene, data which is at present not available. Furthermore, the archaeological evidence has much to tell us about the people living in this area at the time, and how they interacted with the wider environment.

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Friday, 2 December 2022

Magnitude 5.7 Earthquake in Hormozgan Province, Iran.

The United States Geological Survey recorded a Magnitude 5.7 Earthquake at a depth of 4.7 km roughly 49 km to the northeast of the port of Bandar-e Lengeh in Hormozgan Province, Iran, slightly after 6.45 pm local time (slightly after 3.15 pm GMT) on Wednesday 30 November 2022. There are no reports of any damage or casualties associated with this event, but many people in the United Arab Emirates reported feeling it.

The location of the 30 November 2022 Hormozgan Province Earthquake. USGS.

Iran is situated on the southern margin of the Eurasian Plate. Immediately to the south lies the Arabian Plate, which is being pushed northward by the impact of Africa from the south. This has created a zone of faulting and fold mountains along the southwest coast of the country, known as the Zagros Thrust Belt, while to the northeast of this the geology is dominated by three large tectonic blocks, the Central Iran, Lut and Helmand, which move separately in response to pressure from the south, stretching and compressing the rock layers close to the surface and creating frequent Earthquakes, some of which can be very large.

The movement of the Arabian Plate and extent of the Zagros Thrust Belt. Rasoul Sorkhabi/Geo ExPro.

The population of Iran is particularly at risk from Earthquakes as, unlike most other Earthquake-prone nations, very few buildings in the country are quake-resistant. The majority of residential buildings in Iran are made of mud-brick, a building material particularly vulnerable to Earthquakes as the bricks often liquefy, trapping people inside and quickly asphyxiating them with dust. This is particularly dangerous at night when the majority of people are inside sleeping.

Section through the Zagros Fold Belt. Sarkarinejad & Azizi (2007).

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