Oxynoemacheilus kottelati: A new species of Stone Loach from the Aegean drainage of Anatolia.

Stone Loaches of the genus Oxynoemacheilus are found across the Eastern Mediterranean, the southern Caucasus, Anatolia, Mesopotamia, and Central Iran. To date, 67 species have been assigned to the genus, of which are found in Turkish inland waters, and 36 entirely endemic to the country. Sixteen species are found within the Tigris and Euphrates basins, 14 within rivers and streams draining into the Mediterranean, six in rivers and streams draining into the Black Sea, four in rivers and streams draining into the Caspian, two species within the Konya Basin, two within the Marmara Basin, and one within the Van Basin. 

In a paper published in the journal Zoosystematics and Evolution on 9 May 2024, Davut Turan of the Faculty of Fisheries at Recep Tayyip Erdoğan University, Sadi̇ Aksu of the Vocational School of Health Services at Eskişehir Osmangazi University, Sali̇m Serkan Güçlü of the Faculty of Eğirdir Fisheries at Isparta University of Applied Sciences, and Gökhan Kalaycı, also of the Faculty of Fisheries at Recep Tayyip Erdoğan University, describe a new species of Oxynoemacheilus from streams in the Aegean drainage of Anatolia.

The new species is named Oxynoemacheilus kottelati, in honour of the Swiss ichthyologist Maurice Kottelat, for his contributions to our understanding of the world's Fish fauna. The species is described from a series of Fish collected from the Havran and Karınca streams in Balıkesir Province, Turkey, in October 2023.

Oxynoemacheilus kottelati FFR 15655, (a), (b) Holotype, male, 47 mm; FFR 15656; (c) Paratype, female, 49 mm; Türkiye, Balıkesir Province, Havran Stream. Turan et al. (2024).

Specimens of Oxynoemacheilus kottelati range from 35 to 54 mm in length, with a deep body, laterally compressed at the base of the tail. They have a marbled brownish pattern on their flanks and dorsal surface, but are white on the underside. 

Oxynoemacheilus kottelati, FFR 15657, paratypes: (a) male, 47 mm; (b)female, 46 mm; (c) male, 45 mm; Havran Stream; FFR 15656; (d) female, 48 mm; Karınca Stream; Türkiye, Balıkesir Province. Turan et al. (2024).

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Iron Age Illyrian helmet discovered by archaeologists in Croatia.

Archaeologists from the Korčula Town Museum, the University of Zagreb, and Dubrovnik Museums, have uncovered an Iron Age Illyrian helmet at an ancient graveyard on the Peljesac Peninsula in southern Croatia. The helmet was found upright on its own in a separate chamber to any Human burial, leading the archaeologists involved to conclude that it was placed there as a votive offering (an object of value placed in a sacred place as an offering) rather than as grave goods with a specific individual. 

An Illyrian helmet excavated at an Iron Age graveyard on the Peljesac Peninsula in southern Croatia. Marta Kalebota/Korčula Town Museum.

Surprisingly, this is the second such helmet burial found at the cemetery, implying that this was an important ritual activity for the Illyrians of the Peljesac Peninsula. The previous helmet, uncovered in 2020, was dated to about 400 BC, but the style of the newly discovered helmet suggests it to be slightly older, possibly dating to between 500 and 600 BC.

An Illyrian helmet excavated at an Iron Age graveyard on the Peljesac Peninsula in southern Croatia in 2020. Dubrovnik Museums.

The term 'Illyrian' derives from 'Illyrioi' ('Ἰλλυριοί') was used by the Ancient Greeks to describe the peoples of the northwest Balkan Peninsula, and probably refers to a group of peoples with similar cultures and languages rather than a single group  that would have identified as 'Illyrian'. They were regarded as barbarians by both the Greeks and Romans, but appear to have been organised into several distinct kingdoms with well-understood boundaries and trade networks, ruled from walled cities. They were able to hold their territory against potentially aggressive neighbours such as the Greeks, Macedonians, and Thracians, and for a time were considered a maritime power, presenting a threat to shipping on the Adriatic and raiding coastal communities. They proved less able to defend themselves against later Roman incursions, however, and all the Illyrian kingdoms were conquered by Rome in a series of wars between 229 and 168 BC.

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Asteroid 2024 JN16 passes the Earth.

Asteroid 2024 JN16 passed by the Earth at a distance of about 25 400 km (0.07 times the average distance between the Earth and the Moon, or 0.017% of the distance between the Earth and the Sun, but more than 62 times as far from the Earth's surface as the International Space Station), with a relative velocity of about 9.26 km per second, slightly before 9.50 am GMT on Tuesday 14 May 2024. There was no danger of the asteroid hitting us, though were it to do so it would not have presented a significant threat. 2024 JN16 has an estimated equivalent diameter of 2-7 m (i.e. it is estimated that a spherical object with the same volume would be 2-7 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) more than 36 km above the ground, with only fragmentary material reaching the Earth's surface.

120 second image of 2024 JN16 taken with the Celestron 14"-F8/8.4 (356/3000 mm) Schmidt-Cassegrain Telescope at Ceccano in Italy on 5 April 2020. The asteroid is the small point at the centre of the image, indicated by the white arrow, the longer lines are stars, their elongation being caused by the telescope tracking the asteroid over the length of the exposure. Gianluca Masi/Virtual Telescope Project.

2024 JN16 was discovered on 12 May 2024 (two days before its closest approach to the Earth) by Gennady Borisov at the MARGO observatory in Crimea. The designation 2024 JN16 implies that it was the 638th asteroid (object N16 - 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 N16 = 13 + (25 x 16) = 638) discovered in the first half of May 2024 (period 2024 J - the year being split into 24 half-months represented by the letters A-Y, with I being excluded).

The relative positions of 2024 JN16 and the Earth on at 10.00 am GMT on 14 May 2024. JPL Small Body Database.

2024 JN16 is calculated to have a 456 day (1.25 year) orbital period, with an elliptical orbit tilted at an angle of 5.79° to the plain of the Solar System which takes in to 0.89 AU from the Sun (89% of the distance at which the Earth orbits the Sun) and out to 1.43 AU (1.43 times the distance at which the Earth orbits the Sun, somewhat less than the distance at which the planet Mars orbits). 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). 

The relative positions of 2024 JN16, the Earth, and the planets of the Inner Solar System on at 10.00 am GMT on 14 May 2024. JPL Small Body Database.

This means that 2024 JN16 has regular close encounters with the Earth, with the last calculated to have happened in November 2019, and the next predicted for January 2032. 2024 JN16 also has occasional close encounters with the planet Venus, with the next predicted for June 2025.

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Magnitude 6.4 Earthquake off the coast of the Mexico/Guatemala border.

The United States Geological Survey recorded a Magnitude 6.4 Earthquake at a depth of 75.4 km, approximately 17 km off the south coast of the border between Mexico and Guatemala, slightly before 5.40 am local time (slightly before 11.40 am GMT) on Sunday 12 May 2024. This even was felt across much of southern Guatemala, and Chiapas State, Mexico, and triggered a number of small landslides as well as minor damage to some buildings, but there are no reports of any injuries.

The approximate location of the 12 May 2024 Mexico/Guatemala Earthquake. Contour lines show rates of movement during the quake, the red line is the Middle American Trench. USGS.

Mexico is located on the southernmost part of the North American Plate. To the south, along the Middle American Trench, which lies off the southern coast off Mexico, the Cocos Plate is being subducted under the North American Plate, passing under southern Mexico as it sinks into the Earth. Guatemala is located on the southern part of the Caribbean Plate, close to its boundary with the Cocos Plate, which underlies part of the east Pacific. The Cocos Plate is being pushed northwards by expansion of the crust along the East Pacific Rise, and is subducted beneath the Caribbean Plate along the Middle American Trench. This is not a smooth process, and the plates frequently stick together then break apart as the pressure builds up, causing Earthquakes on the process. 

The position of the Cocos, Nazca and Rivera Plates. MCEER/University at Buffalo.

The Cocos Plate is thought to have formed about 23 million years ago, when the Farallon Plate, an ancient tectonic plate underlying the East Pacific, split in two, forming the Cocos Plate to the north and the Nazca Plate to the south. Then, roughly 10 million years ago, the northwesternmost part of the Cocos Plate split of to form the Rivera Plate, south of Beja California.

In a paper published in the Journal of Geophysical Research, in 2012, a team led by Igor Stubailo of the Department of Earth and Space Sciences at the University of California Los Angeles, published a model of the subduction zone beneath Mexico using data from seismic monitoring stations belonging to the Mesoamerican Seismic Experiment, the Network of Autonomously Recording Seismographs, the USArray, Mapping the Rivera Subduction Zone and the Mexican Servicio Sismologico Nacional.

The seismic monitoring stations were able to monitor not just Earthquakes in Mexico, but also Earthquakes in other parts of the world, monitoring the rate at which compression waves from these quakes moved through the rocks beneath Mexico, and how the structure of the rocks altered the movement of these waves.

Based upon the results from these monitoring stations, Stubailo et al. came to the conclusion that the Cocos Plate was split into two beneath Mexico, and that the two plates are subducting at different angles, one steep and one shallow. Since the rate at which a plate melts reflects its depth within the Earth, the steeper angled plate melts much closer to the subduction zone than the shallower angled plate, splitting the Trans-Mexican Volcanic Belt into sections above the different segments of the Cocos Plate, and causing it to apparently curve away from the subduction zone.

Top the model of the Cocos Plate beneath Mexico, split into two sections (A & B) subducting at differing angles. (C) Represents the Rivera Plate, subducting at a steeper angle than either section of the Cocos Plate. The Split between the two has been named the Orozco Fracture Zone (OFZ) which is shown extended across the Cocos Plate; in theory this might in future split the Cocos Plate into two segments (though not on any human timescale). Bottom Left, the position of the segments on a map of Mexico. Darker area is the Trans-Mexican Volcanic Belt, orange circles are volcanoes, brown triangles are seismic monitoring stations, yellow stars are major cities. Bottom Right, an alternative model showing the subducting plate twisted but not split. This did not fit the data. Stubailo et al. (2012).

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Setapedites abundantis: A stem-group Euchelicerate from the Ordovician Fezouata Shale of Morocco.

The Euchelicerates are a large group of Arthropods, comprising the living Arachnids and Xiphosurans (Horseshoe Crabs), as well as extinct groups such as the Eurypterids (Sea Scorpions), Chasmataspidids and the Synziphosurines. The closest living relatives of the Euchelicerates are the Pycnogonids (Sea Spiders), with the two groups together forming the Chelicerata. However, the closest outgroup to the Euchelicerata among the Arthropod groups of the Lower Palaeozoic is less certain, with groups such as the Megacheira, Artiopoda, Vicissicaudata, and Habeliida all suggested. Understanding the relationship between Euchelicerates and other Arthropods is dependent on understanding the order in which the group acquired its key features, i.e. the chelicerae (frontal appendages) from which the group gets its name, and the organisation of the body segments into two divisions, the prosoma, which hosts both the sensory organs and the walking limbs, and the opisthosoma, which hosts the book gills. The Synziphosurines, a (possibly paraphyletic or polyphyletic) stem group of Euchelicerates known from Silurian to Carboniferous deposits, are thought to offer a potential key to this, although very few complete specimens are known. Two noteworthy Synziphosurines (and the two earliest known species to date) are Offacolus kingi and Dibasterium durgae, both from the Silurian Herefordshire Lagerstätte of England, both of which have biramous (branching) limbs (a trait unknown in more derived Euchelicerates), and which have been consistently recovered as the two basalmost Euchelicerates in phylogenetic analyses.

In a paper published in the journal Nature Communications on 7 May 2024, Lorenzo Lustri of the Institute of Earth Sciences at the University of Lausanne, Pierre Gueriau, also of the  Institute of Earth Sciences at the University of Lausanne, and of the Université Paris-Saclay, and Allison Daley, again of the Institute of Earth Sciences at the University of Lausanne, describe a new species of Synziphosurine Euchelicerate from the Early Ordovician Fezouata Shale of Morocco, and discuss the implications of this species for the origin of the Euchelicerate clade.

The Fezouata Shale is noteworthy for the production of a large number of exceptionally preserved Arthropods, as well as Molluscs and Echinoderms dating to about 478 million years ago, during the early stages of the Great Ordovician Biodiversification Event, providing key insights into this interval in the history of life.

The new species is named Setapedites abundantis, where 'Setapedites' means 'hair-foot', in reference to the presence of a brush-like arrangement of hairs on its prosomal exopods (feet), and 'abundantis' refers to the super-abundant nature of the species, which is one of the most numerous fossils in the Fezouata Shale. The species is described from two large collections of specimens, each comprising hundreds of individuals, belonging to the Musée cantonal de géologie Lausanne, and the Yale Peabody Museum.

Dorsal anatomy of Setapedites abundantis. (A), (B) MGL.102899 and interpretative drawing, articulated specimen in dorsal view. (C(, (D) MGL.102828 and interpretative drawing, articulated specimen in dorsal view. (E), (F) MGL. 102872 and interpretative drawing, articulated specimen in dorsal view. Abbreviations: btg, bipartite tergites; mr, median ridge; pl, pleura; pr, prosomal rim; saxn, sub-axial node; sr, sunken region; t1–11, tergites 1–11; t, telson; tk, telson keel. Scale bars, (A)–(F) 1 mm. Lustri et al. (2024).

Setapedites abundantis possesses an elongate, dorsoventrally flattened body, divided into an anterior prosoma bearing a fused dorsal headshield, and an unfused opisthosoma clearly differentiated into (medially) a pre-abdomen and (posteriorly) an abdomen. Its total length varies between 4.33 and 6.5mm (excluding appendages and telson), its maximum width (prosoma) between 2.23 and 2.9mm.

Prosomal appendicular anatomy of Setapedites abundantis. (A), (B) YPMIP 517932c and interpretative drawing (counterpart), articulated specimen in ventral view. (C), (D) YPM IP 517932c and interpretative drawing, chelicerae, and labrum anatomy detail. (E), (F) Close-up of the prosoma ofMGL.102934 and interpretative drawing, in dorso-lateral view. (G), (H) Close-up of the prosoma of MGL.102634 and interpretative drawing, in ventral view. (I), (J) Close-up of the prosoma of MGL.102800a under alcohol and polarized lighting, and interpretative drawing, in ventral view. Abbreviations: 1–6, podomeres 1–6 of the exopod; ptp, pretelsonic process; bs, basipodite; bst, brush-like setae; che, chelate podomere; db, doublure; lb, labrum; ss, single setae; st, pair of setae. Chelicerae are highlighted in gray, endopods in blue, exopods in green, opisthosomal appendages in red, and the pretelsonic process in purple. Scale bars, (A), (B) 1mm; (C), (D) 100μm; (E)–(K) 500 μm. Lustri et al.  (2024).

A phylogenetic analysis including Setapedites abundantis found that it grouped with Offacolus kingi and Dibasterium durgae, together the family Offacolidae, togther forming the sister group to the Crown Euchelicerates, with the Habeliida forming the closest outgroup.

Phylogenetic position of Setapedites abundantis among Panchelicerates, showing early euchelicerate body plan evolution. Simplified extended majority rule tree of a Bayesian analysis chronogram of Euchelicerate relationships, based on amatrix of 39 taxa and 114 discrete characters, showing the position of Setapedites abundantis within Offacolidae. Lineages extending after the Silurian are indicatedwith arrowheads. Schematic models of the body organization in Habelia, Setapedites abundantis, Dibasterium, Offacolus, and Xiphosurida illustrate the origin and early evolution of Euchelicerate uniramous prosomal appendages and tagmosis. Roman numbers designate somites. Prosoma somites are highlighted in blue, pre-abdomen somites in yellow, abdomen somites in brown, and the possible anal pouch or post-ventral structure (pvs) in purple. Black dorsal lines indicate tergites and cephalotorax. Lustri et al. (2024).

The Pycnogonids (Sea Spiders) have long been seen as the sister group to the Euchelicerates, with the two groups together forming the clade Chelicerata. While they are clearly the closest living Animals to the Chelicerates genetically, the assumption that they are closer than many fossil groups has relied upon morphological similarities, notably the presence of a pair of limbs on the head called the chelifores, which have been assumed to be homologous with the chelicerae of the Euchelicerata, a head tagama made up of four segments, and uniramous limbs.  However, the presence of biramous limbs in both the Offacolidae, recovered as the basalmost stem group of the Euchelicerates and Habeliida, recovered as the closest outgroup, casts doubts upon this analysis. Modern Pycnogonids have a very specialised bodyplan, and the group has a very limited fossil record, making it hard to assess how Sea Spiders are related to Palaeozoic Arthropod groups.

Life reconstruction of Setapedites abundantis. Elissa Sorojsrisom in Lustri et al. (2024).

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