Saturday 16 March 2024

Ctenomys uco: A new species of Tuco-tuco from Mendoza Province, Argentina.

Tuco-tucos, Ctenomys spp., are a large group of burrowing Rodents found in South America from southern Peru to the southern tips of Chile and Argentina. There are currently 68 living members of the genus, eleven of which have beed described in the last decade, during which time the application of genetic analysis to phylogenetic studies has led to the genus being divided into eight well-supported species groups, as well as several other groups with less clear relationships. The Ctenomys mendocinus species group has been the subject of several recent studies, which have led to several new species being erected, as well as a number of previously described species having been recognised as populations of other species, and several lineages identified which appear to be as yet undescribed species. One such population is found in northwestern Mendoza Province, Argentina, with populations at Tupungato and the Valley of Arenales which were previously thought to belong to the species Ctenomys mendocinus having been identified as genetically distinct, although the morphological distinctness of these Tuco-tucos has not been assessed.

In a paper published in the journal Vertebrate Zoology on 8 March 2024, Raquel Alvarado-Larios of the Laboratorio de Filogeografía at the Instituto Argentino de Investigaciones de las Zonas ÁridasPablo Teta of the División Mastozoología at the Museo Argentino de Ciencias Naturales 'Bernardino Rivadavia'Pablo Cuello, also of the Laboratorio de Filogeografía at the Instituto Argentino de Investigaciones de las Zonas Áridas, Pablo Jayat of the Unidad Ejecutora Lillo and the Departamento de Ciencias Básicas y Tecnológicasat the Universidad Nacional de ChilecitoAndrea Tarquino-Carbonell, again of the Laboratorio de Filogeografía at the Instituto Argentino de Investigaciones de las Zonas Áridas, Guillermo D’Elía of the Instituto de Ciencias Ambientales y Evolutivas and the Colección de Mamíferos at the Universidad Austral de Chile, and Paula Cornejo and Agustina Ojeda, again of the Laboratorio de Filogeografía at the Instituto Argentino de Investigaciones de las Zonas Áridas, formally describe the Mendoza Tuco-tuco as a new species, based upon genetic and morphological data.

The new species is named Ctenomys uco, in reference to the Valle de Uco, the region in which the new species was discovered. It is a small Tuco-tuco, reaching 215-263 mm in length, with a drab or dusky drab coat, lighter on the flanks and underside, with the underside sometimes also having a brownish tinge. 

External appearance of Ctenomys uco. (A) CMI 7712 (holotype), from Cajón de Arenales, Tunuyán, Mendoza, Argentina; (B) CMI 7737, from Finca Caicayén II, Tupungato, Mendoza, Argentina. Alvarado-Larios et al. (2024).

While the populations assigned to Ctenomys uco were formerly assigned to Ctenomys mendocinus, but a genetic study based upon the mitochondrial cytochrome b gene found that not just were these populations distinct from Ctenomys mendocinus, but also that they aren't particularly closely related, with Ctenomys uco instead forming a sister species to Ctenomys fochi, and these two together forming the sister taxon to a clade which includes Ctenomys verziCtenomys mendocinus, and Ctenomys flamarioni, as well as two as yet un-named lineages.

Ctenomys uco is known from only two locations, 39 km appart, but Tuco-tucos have been reported elsewhere in the region, which are likely to belong to the same species, for which reason Alvarado-Larios et al. decline to make a detailed assessment of the species distribution or conservation status at this time. The species seems to be solitary in nature, and lives in an environment between the Low Monte and the Southern Andean Steppe at altitudes of 1000 and 2710 m above sealevel. One of the known populations lives largely within vineyards, digging burrows at the foot of vines.

Views of the landscapes at the two known localities of Ctenomys uco. (A )Mendoza, Tunuyán, Cajón de Arenales (type locality), (B) Mendoza, Tupungato, vineyards of Finca Caicayén II (note the burrows at the lower right corner on this photograph). Alvarado-Larios et al. (2024).

The region is close to the Andes, and has a temperate climate with harsh winters, hot summers with cool nights. The mean annual temperature varies between about 10°C and about 15°C, with an average of about 300 mm of rain each year, most of which falls in winter.

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The March Equinox.

The March Equinox will fall at 3.04 am GMT on Wedneday 20 March this year. The Earth spins on its axis at an angle to the plain of the Solar System. This means that the poles of the Earth do not remain at 90° to the Sun, but rather the northern pole is tilted towards the Sun for six months of the year (the northern summer), and the southern pole for the other six months (the southern summer). Thus, twice a year neither pole is inclined towards the Sun, on days known as the equinoxes.

The tilt of the Earth relative to the incoming light of the Sun at the March Equinox. Przemyslaw Idzkiewicz/Wikimedia Commons.

The equinoxes fall each year in March and September, with the March Equinox being the Spring (or Vernal) Equinox in the Northern Hemisphere and the Autumn Equinox in the Southern Hemisphere, while the September Equinox is the Autumn Equinox in the Northern Hemisphere and the Spring Equinox in the Southern Hemisphere. On these two days the day and night are both exactly twelve hours long at every point on the planet, the only days on which this happens.

The tilt of the Earth relative to the Sun at the planet's equinoxes and solstices. Astronomy Group/University of St Andrews.

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Understanding the giant handaxes of the British Lower Palaeolithic.

The Lower Palaeolithic is the earliest stage in the archaeological record from which stone tools are known, and while such ancient tools are rare, they are much more common than the remains of the Hominins which produced them, or any other remains of their activity, thus providing a key insight into the activities of our ancient ancestors. The first bifacial handaxes appear in the African archaeological record about 1.76 million years ago, and are considered to be a significant conceptual leap from the Oldowan core-and-flake technology which preceded them, although whether these axes had an entirely novel function or were a new technological approach to tasks which were already undertaken is unclear. One of the notable manifestations of this technology was the manufacture of 'giant' handaxes, notably larger than other examples of these tools, sufficiently large that archaeologists are divided as to whether they had any practical function at all.

It has been suggested that the purpose of these giant axes may have been social rather than practical, with the production of such tools representing a significant time investment, and therefore being an indicator of patience and commitment to a project. Giant, highly symmetrical handaxes from British sites such as Furze Platt and Shrub Hill have been used to support this hypothesis. An alternative suggestion is that the Hominins involved may have found the manufacture of such giant axes an aesthetically pleasing activity in its own righty, an early sign of artistic expression emerging from the purely functional.

In a paper published in the journal Antiquity on 4 March 2024, Luke Dale of the Department of Archaeology at Durham UniversityAaron Rawlinson, also of the Department of Archaeology at Durham University, and of the Department of Britain, Europe and Prehistory at the British MuseumPete Knowles and Frederick Foulds, again of the Department of Archaeology at Durham University, Nick Ashton, also of the Department of Britain, Europe and Prehistory at the British Museum, David Bridgland of the Department of Geography at Durham University, and Mark White, once again of the Department of Archaeology at Durham University, present the results of a study of giant handaxes from across the British Lower Palaeolithic.

Dale et al. note that symmetry is often cited as a key feature of giant handaxes, but that no previous study appears to have actually looked at whether these axes are actually more symmetrical than other axes from the same period, nor whether the style or frequency of these objects varies over time. 

All giant handaxes are associated with the Acheulean technology, which in Britain was present by Marine Isotope Stage 13, about 500 000 years ago, and may have appeared as early as Marine Isotope Stage 15, about 600 000 years ago, if recent dates for the Fordwich and the Bytham River terraces are correct. The global climate underwent a series of oscilations during the Middle Pleistocene (781 000-126 000 years ago), which in Britain manifested as a series of warm interglacials during which Hominins invaded and settled the landscape, interspersed with colder glacial intervals during which they disappeared. This pattern results in a series of distinct cultural intervals within the British Acheulean, providing a potential opportunity to detect discrete phases in the manufacture of giant handaxes in Britain.

Dale et al. obtained data on 4160 handaxes of all sizes, from 47 sited dating to between Marine Isotope Stage 15 and Marine Isotope Stage 9. For convenience, each (odd) Marine Isotope Stages was considered to represent a warm phase, as well as the cool phases bracketing it, thus Marine Isotope Stage 11 in fact refers to the Marine Isotope Stage 10-11-12 cool-warm-cool cycle; each cycle therefore represents about 100 000 years. The warm phases covered by Dale et al.'s study are MIS 15 (approximately 610 000 to 560 000 years ago), MIS 13 (approximately 524 000-474 000 years ago), MIS 11 (approximately 427 000 to 364 000 years ago), MIS 9 (approximately 328 000-301 000 years ago. Many of the sites in the study are well dated, but others represent chronologically mixed assemblages, such as Dunbridge in Hampshire, where the artefacts were recovered from dredged aggregates, have only been tentatively dated, such as Whitlingham in Norfolk, or are known to have been the subject of collecting biases, such as Furze Platt in Berkshire. Dale et al. recognise that these factors will have an impact on the reliability of their study, but reason that the size of their dataset should offset this. They also note that a further two giant handaxes were discovered at Frindsbury in Kent after the initial daft of their study was submitted, and that these are thought to date to MIS 9.

Handaxes were divided into six classes on the basis of their symmetry, with Class 1 representing near perfect symetry, and Class 6 indicating almost no symmetry.

Dale et al. measured the length of all the 4160 handaxes in their study, splitting them into four categories; small (less than 80 mm in length), average (80-150 mm in length), large (150-220 mm in length) and giant (more than 220 mm in length.

Forty two of the handaxes fell into the 'giant' category, of which 33 can be confidently assigned to the MIS 9 cycle, the final stage of the Acheulian in Britain. A single giant axe was dated to MIS 11, and two to MIS 13 - although one of these is- derived from a MIS 6 gravel bed, and is interpreted as having been reworked from a MIS 13 deposit. Since MIS 9 only represents about 1% of the British Pleistocene record, this concentration of giant handaxes in MIS 9 deposits is interpreted as being significant.

In the 1960s archaeologist Derek Roe developed a system of classifying handaxes upon their shape. The majority of giant handaxes in Dale et al.'s study conform to Roe's Group I (pointed, with cleavers) and Group III (plano-convex), both of which are associated with MIS 9. Notably, handaxes in an assemblage from Broom on the Devon/Dorset border, which included several giant handaxes, while still from MIS 9, did not easily fit into Roe's scheme. The stone tools here were made from chert derived from the Upper Greensand, and tended to be ovate or asymmetrical, unlike other MIS 9 assemblages.

Other than the presence of giant handaxes in the MIS 9 material, the size distribution of handaxes between different interglacials varied little, with the average size of the axes varying only by 10-20%, although the MIS 15 handaxes appear on average slightly larger than those from later assemblages, and the MIS 11 assemblage contained a higher proportion of small handaxes than other stages. However, Dale et al. note that their MIS 15 material came from only two sites, Brandon Fields in Suffolk and Fordwich in Kent, with the material used at Fordwich being elongated pipeflint, which lends itself to the making of larger bifaced tools with a minimal amount of effort. Given this, Dale et al. are reluctant to read much into this data without further MIS 15 material becoming available.

Analysis also suggests that axes from MIS 13 and MIS 9 are on average larger than those from MIS 11, and MIS 9 axes are also slightly larger, on average, than those from MIS 13. Dale et al. are uncertain whether this variation relates to cultural differences between the different populations colonising Britain in each interglacial, and make no further assessment of this data at this time.

A comparison of handaxe length between MIS 15, 13, 11 and 9, with handaxes grouped according to length class. MIS 15 displays a greater proportion of handaxes in the large class, while small handaxes are much more limited. MIS 11 displays a greater proportion of small handaxes. Giant handaxes represent a very small percentage of the total assemblage, emphasising their status as extreme outliers beyond the usual variation in handaxe length. Frederick Foulds & Mark White in Dale et al. (2024).

The majority of giant handaxes come from the Thames Valley or its southern tributaries, although examples are also known from Norfolk Yare, the Axe Valley and Solent River deposits. The majority of sites where they are found are close to primary chalk-flint outcrops, where large flint nodules were available. However, some were found in flint-poor areas, such as Wolvercote and Stanton Harcourt in Oxfordshire, whereas older archaeological sites, such as Boxgrove in West Sussex, and Elveden in Suffolk, are located near excellent sources of large flint nodules, but yield no giant handaxes. 

No giant handaxes available from Stoke Newington in London, one of the UK's best MIS 9 sites, although it is known that the site did yield such axes; as the original excavator of the site, Victorian archaeologist Worthington Smith, illustrated several giant handaxes in his book, Man, the primeval savage, but then gave these away to distinguished visitors to the site; these axes are thought to be either in private collections or lost. 

Geological map displaying the locations of sites with giant handaxes in relation to underlying bedrock geology, coloured as per the British Geological Society scheme. Colours for chalk bedrock are highlighted in the legend. Note that large clasts in overlying superficial deposits largely reflect local geology and ‘exotic’ raw materials would generally be smaller in size. Dale et al. (2024).

Of the forty two giant handaxes in the study, thirty five (or 83%) are pointed, typically conforming to the lanceolate (lance-shaped) or ficron (having a pointed planform shape with biconcave edges) type. These shapes are considered to be part of the same typological grouping as chisel-ended cleavers, a grouping which is thought by many archaeologists to be restricted to MIS 9. Although ficrons are associated with giant axes, not all ficron handaxes are giant; known ficrons range in size from 63 mm to 307 mm.

Examples of giant pointed and ficron handaxes: (A) the ‘Beast of Biddenham’ (length 253 mm); (B) a giant ficron from Canterbury West (length 285mm) (photographs courtesy of the British Museum (A) and The Seaside Museum, Herne Bay (B)). Dale et al. (2024).

Since the overwhelming majority of the giant axes date from MIS 9, Dale et al. examined axes from this stage for their symmetry. Handaxes from this interval were found to vary a great deal in their degree of symmetry, although there was a direct corelation between axe length and symetry, with longer axes tending to be more symmetrical than shorter ones. 

Splitting the axes into groups based upon their size emphasised this trend, with axes in larger categories being more symmetrical than those in smaller size categories. Examination of earlier axes suggested that this tendency for larger axes to be more symmetrical was also present in MIS 11, but not MIS 15 or 13, although the number of axes available from the earlier periods makes this result less reliable. 

However, this tendency for larger axes to be more symmetrical in MIS 11 and 9 deposits may be influenced by another trend, which is for axes in general to be much more symmetrical in MIS 13 and 11, compared to other periods, and in particular to MIS 9. Thus, the increased symmetry seen in the large MIS 9 axes is balanced by a decrease in the symmetry seen in smaller axes, with the smallest axes (less thn 100 mm in length) tending to be roughly and quickly made, with very low symmetry. 

Giant handaxes are often cited as a key feature of Hominin cognitive and cultural development. Dale et al.'s study demonstrates that these items became prevalent in Britain during MIS 9, i.e. immediately prior to the Lower-Middle Palaeolithic transition, 300 000 and 250 000 years ago. This interval has already been identified as one of significant technological innovation, beginning with a non-handaxe phase, which was then followed by a period with handaxes, then a final phase in which a hierachical core-working technology, known as the proto-Levallois was introduced. The linking of giant handaxes to this stage adds another element to this increasing cultural complexity.

The presence of giant handaxes is often independent of the availability of suitable manufacturing materials, with giant handaxes known from areas of Oxfordshire where there are no sources of suitable large flints. This implies that either the raw material or the finished axes were transported for at least 25-40 km to the sites where they were found. This phenomenon has also been observed in France, with a giant handaxe found at Caune de l’Arago in Pyrénées-Orientales Department, more than 30 km from any suitable source of material. This transportation of materials is another new innovation from this phase, with most previous Lower Palaeolithic sites using stone sourced less than 5 km from the location where it was discovered. The increased effort being put into moving giant axes to locations away from the materials from which they were made lends further support to the hypothesis that these were valuable items, although another possibility is that these tools had a long working life, and were subject to regular reworking to maintain a sharp edge, which would explain the plano-convex form of many handaxes, including those at Wolvercote in Oxfordshire. Under this hypothesis, many large handaxes would have been discarded prematurely, before being extensively reduced.

Many of the giant handaxes are ficrons, a type of axe otherwise rare in Britain. Large ficrons are particularly striking objects, apparently crafted with care to maintain the length of the axe while reducing the width of the upper and central portions of the axe. This may have been a way to correct for a lack of symmetry in the original platform (the rock from which the ficron was made), or a sign of the tool having an extended lifespan, with regular resharpening. Another hypothesis is that the width reduction may have been a way to reduce the weight of the tool part of a general Acheulian trend for longer tools to be narrower. The alternative is that the ficron-shape was desired from the outset, and that the extra effort put into producing an axe of this shape is an indicator of the significance of the object to the people who made it. Whatever the truth, there does appear to be a link between the high symetry, large size, and unusual shape of these giant ficrons which appears to show a degree of artistry transcending the merely functional.

It has often been speculated that giant handaxes had no practical function, but experimentation has shown that examples far larger than anything found in Britain can be used as tools. Even the largest giant axes can be used two handed, can be used for digging, or can be used as static cutting tools across which materials could be drawn. Despite this possible functionality, all the British giant handaxes are distinctively formed and highly symmetrical, making it hard to believe that aesthetic considerations played no part in their manufacture. 

The oldest known giant axe is 1.6 million years old, and came from the Olduvai FLK West site in Tanzania. This is long before anything else considered to be even possibly an expression of communal artistic standards, and therefore was presumably made by an individual for reasons that were important to them alone. A more communal approach to aesthetics begins to appear about 500 000 years ago, at which point tools also being to appear which have been shaped to make the most of features such as fossils on the rock cortex. Giant handaxes may also represent an aesthetic development, with the size and symmetry of stone tools being increased to create visually pleasing objects. This implies the people who made these tools were capable in taking pleasure in creating such objects, which would imply an increasing level of cognitive and social development.

Giant handaxes may also have had some symbolic purpose. The manufacture and then apparent discarding of objects which take a degree of forward planning and labour investment may have been a way of marking territory, or signposting important locations to other members of the community.

The ability to produce giant handaxes clearly predates MIS 9; they are known from earlier in the Lower Palaeolithic and across the Acheulean world. A 300 mm-long lanceolate giant handaxe from Caune de l’Arago is thought to date from MIS 14, and other examples from across northern France, at sites including St Acheul and Thennes in the Somme Valley, Vaudricourt in Pas-de-Calais, and Montguillain in Oise Department, have variously been dated to MIS 11 and 9, although none of these dates are considered to be particularly secure. Giant handaxes are also known from the Levant and Middle East, though these tend to be less accurately dated. A 220 mm long example from Qesem Cave in Israel is thought to be between 420 000 and 200 000 years old, while a 265 mm-long basalt handaxe was found at Wadi Dabsa in Saudi Arabia. A site at Porto Maior in north-west Spain was occupied for a long interval across MIS 8-7, by a people of apparent African affinities, who regularly produced giant handaxes, picks and cleavers. Giant handaxes have been found at 23 sites across Africa, including Olduvai in Tanzania, where the largest such axe is 330 mm long and 1.4 million years old, Isenya in Kenya, where the largest axe is 253 mm long and 700 000 years old, and Kalambo Falls in Zambia, where the largest axe is 350 mm long and 300 years old. However, the African Acheulian, with which many sites in southern Europe and the Middle East are also associated, has a greater emphasis on large cleavers, picks, and handaxes, together referred to as 'large cutting tools'.

The MIS 9 giant handaxes from Britain appear to show a different phenomenon, a discrete technological interval in which larger, more symmetrical tools suddenly appeared. In France, the MIS 9 sites in the Somme Valley are the closest available to compare, with the Cagny l’Epinette locality producing 33 handaxes, the largest of which is still less than 170 mm in length, while the Revelles site has produced 52 handaxes, none more that 190 mm long. Ferme de l’Epinette, a MIS 10 site in the Somme Valley has produced 31 handaxes, all less than 180 mm long, while the MIS 9 stage of the Soucy complex in the Paris Basin has produced 178 handaxes, the largest of which are 155 mm long, and no handaxe from the entire complex exceeds 180 mm. The Orgnac Cave site in the Ardèche Department has a sequence of archaeological layers running from MIS 10 to MIS 8, but has produced no handaxes more than 200 mm in length. The MIS 9 layers at Menez-Dregan in Brittany have produced 29 handaxes, all less than 160 mm in length, although this may be because the tools are made from sandstone and microgranite beach pebbles which would not lend themselves to making bigger tools. This lack of large rocks for use as a source of tools may also account for the generally small handaxes found at Atapuerca in Spain.

Thus the production of giant handaxes in Britain appears to be a geographically, as well as chronologically, restricted phenomenon. This fits in with a more modern understanding of the Acheulian Culture, which includes many such small-scale variations, rather than being a single long-lived and widespread monoculture, as was once perceived. 

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Thursday 14 March 2024

Comet C/2021 S3 (PANSTARRS) makes its closest approach to the Earth.

Comet C/2021 S3 (PANSTARRS) will pass by the Earth at a distance of 194 168 000 km (130% of the distance between the Earth and the Sun), on Friday 15 March 2024. At this time the comet will be in the constellation of Aquila, with a magnitude of 7.20, which is bright enough to be visible with a small telescope or large pair of binoculars.

An image of Comet C/2021 S3 (PANSTARRS) taken on 5 February 2023 with the iTelescope T30 Telescope at Siding Spring Observatory in New South Wales. The image is a composite of three 180 second images. Taras Prystavski/Astrobin.

Comet C/2021 S3 (PANSTARRS) was discovered on 26 September 2021 by the PANSTARRS sky survey, located at Haleakala Observatory, Hawaii. The name C/2021 S3 (PANSTARRS) implies that it is a Comet (C/), that it was the 3rd comet discovered in the second half of September 2021 (period 2023 S), and that it was discovered by the PANSTARRS sky survey.

Comet C/2021 S3 (PANSTARRS) is a Parabolic Comet, which is to say a comet that was disrupted from an orbit in the Oort Cloud, and is passing through the Inner Solar System on a parabolic orbit that will probably not bring it back again. This parabolic trajectory is tilted at an angle of 58.53° to the plain of the Solar System.

The trajectory of Comet C/2021 S3 (PANSTARRS), and its position aon 15 March 2024. JPL Small Body Database.

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Wednesday 13 March 2024

Dinocephalosaurus orientalis: New specimens shed new light upon a remarkable marine Archosauromorph from the Middle Triassic of southwestern China.

Archosauromorphs first appeared in the Permian, and became the dominant Vertebrate group in terrestrial ecosystems during the Mesozoic. While Archosauriform groups such as the Pseudosuchians (Crocodile-lineage Archosaurs) and Avemetatarsalians (Pterosaurs and Dinosaurs) became the dominat groups of Archosaurs from the Jurassic onwards, a variety of non-Archosauriform Archosauromorphs, such as the Rhynchosauria, Allokotosauria, and Tanystropheidae played an important role in Triassic ecosystems. The Tanystropheidae are one of a number of groups of highly gracile (slender) Triassic Archosauromorphs, once thought to represent a single clade, but now thought to be a loose group of basal Archosauromorphs, refered to as non-Crocopodans, where the Crocopodans comprise the Rhynchosauria, Allokotosauria, and Archosauriforms.

These gracile non-Crocopodans were a diverse group, inhabiting terrestrial, freshwater, and marine environments, and in one case (Ozimek volans),  possibly taking to the air. However, their delicate skeletons did not favour preservation, and many species are known only from compressed and fragmentary remains. One such species is Dinocephalosaurus orientalis, a non-Crocopodan Archosauromorph from the Middle Triassic Guanling Formation of Guizhou Province, China, which was described in 2003 from a specimen comprising an isolated, well-preserved skull and the first three anterior cervical vertebrae preserved in articulation. Subsequent specimens revealed that Dinocephalosaurus orientalis was of similar size and proportions to the better known Tanystropheus longobardicus, but while both species have extremely elongated necks, exceeding the lengths of their trunks, the  neck of Tanystropheus longobardicus has 13 elongated  cervical vertebrae, whereas Dinocephalosaurus orientalis has at least  32 vertebrae in  its  neck.  Furthermore, a specimen which cannot confidently be assigned to the species, but which must clearly be closely related, was found to be gravid, with an embryo (not an egg) within its abdominal cavity, indicating the birth of live young, almost certainly an adaptation to a fully marine lifestyle.

In a paper published in journal Earth and Environmental Science Transactions of the Royal Society of Edinburgh on 23 February 2024, Stephan Spiekman of the Staatliches Museum für Naturkunde Stuttgart, Wei Wang of the Institute of Vertebrate Palaeontology and Palaeoanthropology of the Chinese Academy of Sciences, Lijun Zhao of the Zhejiang Museum of Natural History, Oliver Rieppel of the Field Museum of Natural History, Nicholas Frazer of National Museums Scotland, and Chun Li, also of the Institute of Vertebrate Palaeontology and Palaeoanthropology of the Chinese Academy of Sciences, describe five new specimens of Dinocephalosaurus orientalis, and discuss their implications for our understanding of the species. 

The holotype of Dinocephalosaurus orientalis. (a) Photograph. (b) Photograph with interpretative drawing. Abbreviations: fr, frontal; j, jugal; la, lacrimal; mx, maxilla; na, nasal; op, opisthotic; pa, parietal; pl, palatine; pm, premaxilla; pof, postfrontal; po, postorbital; pro, prootic; pt, pterygoid; scl, sclerotic plates; soc, supraoccipital; sq, squamosal. Spiekman et al. (2024).

The first additional specimen described by Spiekman et al., IVPP V13898, has previously been described in 2008, and is the specimen upon which most of our current understanding of the species is based. This specimen comprises the skull, most of the vertebral column, elements of all four limbs and some elements of the pectoral and pelvic girdle. This specimen is more complete than the holotype (first specimen described), however, the skull is relatively poorly preserved, strongly dorsoventrally compressed and exposed in ventral view.

Dinocephalosaurus orientalis, IVPP V13898 (referred specimen). (a) Photograph. (b) Interpretative drawing. Spiekman et al. (2024).

The second next specimen, IVPP V17977, is described for the first time, as are all subsequent specimens. This specimen comprises the skull and mandible preserved in ventral view on one block, followed by the first to the 16th cervical vertebrae, together with associated cervical ribs, preserved in articulation on three additional slabs.

Dinocephalosaurus orientalis, IVPP V17977 (referred specimen). (a) The specimen as preserved on four slabs (photograph, scale bar in cm). (b) Interpretative drawing of the skull, lower jaw and cervical vertebrae 2–9. Abbreviations: ang, angular; ax, axis; bs, basisphenoid; cv, cervical vertebra; d, dentary; ncr, neural crest; oph, opisthotic; pl, palatine; poz, postzygapophysis; prz, prezygapophysis; pt, pterygoid; q, quadrate; v, vomer. Spiekman et al. (2024).

The second new specimen, ZMNH M8727, comprises elements of an exploded skull, a total of 28 cervical vertebrae of which the axis and the following 17 cervical vertebrae are preserved in articulation; two scattered vertebrae located next to the 28th cervical vertebra, one of them exposed in anterior view, a string of six vertebrae lying in front of the remains of the pectoral girdle and forelimbs, plus associated cervical, dorsal and gastral ribs.

Dinocephalosaurus orientalis, ZMNH M8727 (referred specimen). (a) Photograph. (b) Interpretative drawing. Abbreviations: ax, axis; co, coracoid; d, dentary; hu, humerus; mx, maxilla; pm, premaxilla; pt, pterygoid; q, quadrate; ra, radius; sc, scapula; ul, ulna. Spiekman et al. (2024).

The third new specimen, ZMNH M8728, comprises a partially preserved skull exposed in right lateral view, plus the cervical and most of the dorsal vertebral column represented by 56 vertebrae preserved in articulation (i.e. 32 cervical vertebrae and 23 dorsal vertebrae), cervical and dorsal ribs; elements of both pectoral girdles and forelimbs; and the gastral rib basket.  

Dinocephalosaurus orientalis, ZMNHM8728 (referred specimen). (a) Photograph. (b) Interpretative drawing. Abbreviations: cl, clavicle; co, coracoid; co-sc, articulated coracoid and scapula; cr, cervical rib; cv, cervical vertebra; hu, humerus; ns, neural spine; ra, radius; ul, ulna. Spiekman et al. (2024).

The next new specimen, ZMNH M8752, comprises the skull and mandible, neck, trunk and complete tail, ribs, gastral ribs, pectoral girdle and forelimbs as well as pelvic girdle and hindlimbs, making it one of the most complete specimens known.

Dinocephalosaurus orientalis, ZMNH M8752 (referred specimen). (a) Photograph. (b) Interpretative drawing. Abbreviations: as, astragalum;  ca, calcaneum; ca.v, caudal vertebra; cl, clavicle; co, coracoid; cv, cervical vertebra; do.v, dorsal vertebra; dt, distal tarsal; fib,  fibula; hu, humerus; in, intermedium; mand, mandible; ra, radius; sc, scapula; tib, tibia. Spiekman et al. (2024).

The final new specimen, IVPP V20295, however, is the most complete and fully articulated specimen recovered to date, comprising a skull is preserved in dorsal view and is in complete articulation with the neck and the rest of the body, which is essentially exposed on its left side. The total vertebral count is 145, comprising 32 cervical vertebrae, 30 dorsal vertebrae, 2 sacral vertebrae and 81 caudal vertebrae.

Dinocephalosaurus orientalis IVPP V20295.Complete articulated skeleton in dorsal to left lateral view. Abbreviations: ax, axis; ca.v, caudal vertebra; cv, cervical vertebra; do.v, dorsal vertebra; ga, gastralia; l.co, left coracoid; l.fe, left femur; l.hu, left humerus; l.il, left ilium; l.is left  ischium; l.man, left manus; l.pes, left pes; l.pu, left pubis; l.ra, left radius; l.sc, left scapula; r.hu, right humerus; r.co, right coracoid; r.fi, right fibula; r,ma, right manus; r.ra, right radius; r.sc, right scapula; r.ti, right tibia; r.ul, right ulna. Spiekman et al. (2024).

Based upon this new material, Spiekman et al. re-interpret Dinocephalosaurus orientalis as a large non-Crocopodan Archosauromorph, reaching as much as 6 m in length, with a neck twice as long as its trunk. It's post-orbital skull is short, and the suborbital fenestra has been obliterated. There is a single fang on each pre-maxillary, as well as further fangs on the front part of the maxilla and dentary. There are 62 pre-sacral vertebrae, of which 32 are cervical, as well as two sacral vertebrae and 81 caudal vertebrae. The limbs are reduced, apparently due to paedomorphosis (the retention of juvenile traits in adults), with a lack of suturing in several places in clearly adult specimens, and a reduction in the number of phalanges.

Dinocephalosaurus orientalis, ZMNHM8728, interpretative drawings of selected elements. (a) Right mandibular ramus in lateral view. (b) Right pterygoid in lateral view. (c) Posterior cervical vertebrae and anteriormost dorsal vertebra (cv26–do.v1) in right lateral view. (d) Mid-dorsal vertebrae in right lateral view. (e) Right forelimb, as preserved. (f) Left forelimb, as preserved. Abbreviations: ang, angular; ar, articular; c, centrum; cv, cervical vertebra; d, dentary; dc, distal carpal; do.v, dorsal vertebra; hu, humerus; int, intermedium; mc, metacarpal; ncr, neural crest; ns, neural spine; pl.p.pt, palatine process of the pterygoid; poz, postzygapophysis; prz, prezygapophysis; q.p.pt, quadrate process of the pterygoid; sang, surangular; sym, symphysis; tr.p, transverse process; tr.p.pt, transverse process of the pterygoid; ra, radius; rad, radiale; ul, ulna; uln, ulnare. Spiekman et al. (2024).

Spiekman et al. also note that a specimen of an aparently gravid Dinocephalosaurus has been described from a different location, Luoping County in Yunnan Province. This specimen is incomplete making confident assignment to the same species difficult, but has no traits which would justify erecting a second species. Notably, although presumably an adult, this specimen is only about half  the size of the largest specimens from the Guanling Formation specimens, suggesting  that if it does belong to the same species, then that species  must have  shown strong sexual dimorphism.

Specimens of Dinocephalosaurus orientalis are quite abundant in the Guanling Formation, a coastal deposit laid down in the eastern Tethys Ocean, but no similar specimens have to date been found in deposits from the western Tethys, which outcrop in Europe and the Middle East, despite many of these sites having been sampled extensively for over three centuries. However, based upon their new material, Spiekman et al. not that two maxillae from the Lower Muschelkalk of Krapkowice and Gogolin in Upper Silesia, Poland, and a dentary from the Lower Muschelkalk of Winterswijk in the Netherlands, currently assigned to 'Lamprosauroides goepperti', show strong similarities to Dinocephalosaurus orientalis, although the extremely fragmentary nature of this European material prevents a proper re-evaluation at this time.

Extremely elongate necks appear to have been achieved at least twice in non-Crocopodan Archosauromorphs, with Dinocephalosaurus orientalis increasing the number of vertebrae in its neck, while Tanystropheus spp. increased the length of the individual cervical vertebrae. While this might seem likely to have given Dinocephalosaurus orientalis a more flexible neck than Tanystropheus spp., both taxa had elongated cervical ribs which would have served to stiffen the neck, something widespread in non-Crocopodan Archosauromorphs. 

It is possible thar the arrangement of cervical ribs and an elongate neck would have facilitated suction feeding, however, both taxa have 'fish-trap' dentition, suggesting that this is unlikely, as the long teeth would tend to prevent prey being drawn into the buccal cavity. Instead Spiekman et al. theorise that both taxa probably caught prey with a lateral snapping motion of the head, something which has also been proposed for piscivorous Triassic Sauropterygians. 

Restoration of Dinocephalosaurus orientalis. The skull in (a) left lateral; (b) dorsal; and (c) ventral views. (d) The skeleton in left lateral view with a silhouette of a diver for scale. Abbreviations; ect, ectopterygoid; fr, frontal; j, jugal; la, lacrimal; mx, maxilla; na, nasal; pa, parietal; pal, palatine; pm, premaxilla; po, postorbital; pof, postfrontal; prf, prefrontal; pt, pterygoid; q, quadrate; sq, squamosal; vo, vomer. Spiekman et al. (2024).

The largest specimens of Dinocephalosaurus orientalis are considered to be adults with some confidence, showing full fusion of the bones of the skull and trunk region. Notably, a specimen from the Triassic of Yunnan, which appears very similar to Dinocephalosaurus orientalis, but is not complete enough to confidently assign to the species, is gravid, suggesting either that Dinocephalosaurus orientalis was sexually dimorphic, or that a second, much smaller species of Dinocephalosaurus was also present. The limbs of Dinocephalosaurus orientalis are underdeveloped, with little development of articular surfaces and poorly ossified carpus and tarsus, even compared to the functionally similar Tanystropheus spp., suggesting that Dinocephalosaurus orientalis had a greater degree of adaption to a marine environment, and was probably not capable of leaving the water and crawling onto land. 

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