Unnamed Form Research Articles

Within the forest: a new species of Ctenomys (Rodentia: Ctenomyidae) from northwestern Patagonia

Abstract The genus Ctenomys is represented by 68 species within at least 9 species groups. In Patagonia, there are 11 described species of Ctenomys in 3 phylogenetic species groups: (1) the sociabilis group; (2) the magellanicus group; and (3) the mendocinus group—added to this is C. maulinus, which is not clearly related to any species group. The magellanicus group is the most representative of Patagonia and includes 6 species, several unnamed forms, and has a widespread distribution from Río Negro and Neuquén provinces in the north of Patagonia to Tierra del Fuego province to the south. The magellanicus group is a highly supported clade and comprises 3 geographically defined lineages: the bidaui clade (northern clade) composed of C. bidaui, C. pulcer, and several undescribed forms; the polytypic haigi clade (central clade) comprising C. haigi, C. contrerasi, C. thalesi, C. sericeus, and Ctenomys cf. C. lentulus (sensu Teta and D’Elía 2020); and the monotypic magellanicus clade (southern clade) consisting of haplotypes assigned to C. magellanicus (including C. colburni). Ctenomys magellanicus (Magellanic Tuco-tuco) is widely distributed from southern Santa Cruz province in Argentina and central Aysén in Chile to Isla Grande de Tierra del Fuego in Argentina and Chile. Based on mitochondrial Cytochrome b DNA sequences and morphological assessment (qualitative and quantitative), we describe a new species of Ctenomys related to C. magellanicus from northwestern Chubut Province, Argentina. We provide anatomical comparisons between the new species and other species of Ctenomys from Patagonia, especially C. magellanicus, C. haigi, and C. plebiscitum. In addition, we recognize 2 groupings within C. magellanicus because of their morphometric differences, and report new localities for C. haigi and C. plebiscitum.

AVIAN FORAGING ON AN INTERTIDAL MUDFLAT SUCCESSION IN THE EOCENE TANJUNG FORMATION, ASEM ASEM BASIN, SOUTH KALIMANTAN, INDONESIAN BORNEO

Abstract Moderately diverse trace fossil assemblages occur in the Eocene Tambak Member of the Tanjung Formation, in the Asem Asem Basin on the southern coast of South Kalimantan. These assemblages are fundamental for establishing depositional models and paleoecological reconstructions for southern Kalimantan during the Eocene and contribute substantially to the otherwise poorly documented fossil record of birds in Island Southeast Asia. Extensive forest cover has precluded previous ichnological analyses in the study area. The traces discussed herein were discovered in newly exposed outcrops in the basal part of the Wahana Baratama coal mine, on the Kalimantan coast of the Java Sea. The Tambak assemblage includes both vertebrate and invertebrate trace fossils. Invertebrate traces observed in this study include Arenicolites, Cylindrichnus, Diplocraterion, Palaeophycus, Planolites, Psilonichnus, Siphonichnus, Skolithos, Thalassinoides, Taenidium, and Trichichnus. Vertebrate-derived trace fossils include nine avian footprint ichnogenera (Aquatilavipes, Archaeornithipus, Ardeipeda, Aviadactyla, cf. Avipeda, cf. Fuscinapeda, cf. Ludicharadripodiscus, and two unnamed forms). A variety of shallow, circular to cylindrical pits and horizontal, singular to paired horizontal grooves preserved in concave epirelief are interpreted as avian feeding and foraging traces. These traces likely represent the activities of small to medium-sized shorebirds and waterbirds like those of living sandpipers, plovers, cranes, egrets, and herons. The pits and grooves are interpreted as foraging traces and occur interspersed with both avian trackways and invertebrate traces. The trace fossils occur preferentially in heterolithic successions with lenticular to flaser bedding, herringbone ripple stratification, and common reactivation surfaces, indicating that the study interval was deposited in a tidally influenced setting. Avian trackways, desiccation cracks, and common rooting indicate that the succession was prone to both subaqueous inundation and periodic subaerial exposure. We infer that the Tambak mixed vertebrate-invertebrate trace fossil association occurred on channel-margin intertidal flats in a tide-influenced estuarine setting. The occurrence of a moderately diverse avian footprint and foraging trace assemblage in the Tambak Member of the Tanjung Formation illustrates that shorebirds and waterbirds have been using wetlands in what is now Kalimantan for their food resources since at least the late Eocene.

Непредоставление информации о кредитном продукте как непоименованная форма недобросовестной конкуренции

This article discusses some unfair practices in the field of lending, as an unnamed form of unfair competition by providing incomplete and/or unreliable information about the features of the credit products being sold to citizens-consumers. These practices were reviewed by the author taking into account the current legislation and existing practical problems.

A diverse organic-walled microfossil assemblage from the Mesoproterozoic Xiamaling Formation, North China

The mid-Proterozoic (ca. 1.85–0.85 Ga) might have been environmentally “boring”, but was a crucial interval of time for the early establishment of eukaryotic life on Earth. The Mesoproterozoic shale-dominated Xiamaling Formation (ca. 1.4–1.35 Ga) in North China preserved abundant organic-walled microfossils, some of which were of eukaryotic affinity but their taxonomic diversity and evolutionary implications remain unclear. In this paper, we present a palynological study of the lower Xiamaling Formation in the northern Tianjin Municipality. Similar to other Mesoproterozoic microbiotas, this assemblage consists of well-preserved and diverse spheroidal to ellipsoidal vesicles, filamentous microfossils and cellular aggregates. In total, 36 species belonging to 28 genera are identified, including 1 new species Quadrimurus clavatus gen. et sp. nov., and 5 unnamed forms. Majority of these taxa are recognised for the first time from this formation, indicating a richer assemblage than previously known. Although most taxa are of unknown biological affinities, this microbiota is thought to be composed of prokaryotic and eukaryotic microorganisms, in which 12 taxa are inferred to be eukaryotic. These microfossils indicate a moderate diversity of eukaryotic life documented in the Xiamaling Formation, which is consistent with other microbiotas in the mid-Proterozoic. The presence of Jixiania lineata Yan, 1986 (=Lineaforma elongata Vorob’eva and Sergeev, 2015) in North China extends its geographic distribution and further enhances its potential as index fossil for the early Mesoproterozoic strata. The Xiamaling assemblage provides one of the broader pictures of the Mesoproterozoic biosphere, in which eukaryotes were predominantly protistan-grade microorganisms.

Corrigendum: The Collins’ monster, a spinous suspension‐feeding lobopodian from the Cambrian Burgess Shale of British Columbia

In the recent publication by Caron & Aria (2020), the proposed new family-group name ‘Teratopodidae’ is not available because it is not formed from the stem of an available generic name (ICZN 1999; Art. 11.7.1.1). A replacement name is proposed here, along with corrected Remarks. urn:lsid:zoobank.org:act:41E7E111-B628-42DC-AE3A-0290D5F25DB3 After the type genus Collinsovermis. Acinocricus Conway Morris & Robison, 1988, unnamed form from Emu Bay Shale (García-Bellido et al. 2013), Collinsium Yang et al., 2015, Collinsovermis Caron & Aria, 2020. Luolishaniid lobopodians with stout bodies and paired spinules on anterior lobopods up to c. 2.5 times as long as lobopod diameter, and spaced apart c. 1/3 of lobopod diameter. Collinsovermidae differ from other luolishaniid lobopodians by the length and spacing of their appendicular spinules, as diagnosed above. The need to create a familial-level rank arises with the demonstrated cladistic grouping of Collinsovermis,Acinocricus and Collinsium, which is helpful in discussing diversity across an ever larger luolishaniid clade. The extent of the presence of long and elongate dorsal spines is another potential character that could inform the monophyly of this group or a sub-group within Collinsovermidae, since spines at least twice as long as body diameter in Luolishania are present only on a few post-frontal somites, possibly from somite 2 to somite 4, whereas they cover most of the body in Acinocricus,Collinsium and Collinsovermis. The seemingly shorter spine length in the EBS taxon and its incompleteness cast doubt on the validity of this character, although it may mean that the EBS form occupies a basal position within Collinsovermidae. Likewise, we identified that an antero-lateral change in spine number per set characterised Acinocricus,Collinsovermis and, less markedly, Collinsium, but we cannot be sure at present whether this trait is diagnostic of Collinsovermidae as a whole. This published work and the nomenclatural act it contains, have been registered in ZooBank: http://zoobank.org/References/D5551921-7DCA-4B7E-B8B1-85FF5EBD711D

Revision of Plioperdix (Aves: Phasianidae) from the Plio-Pleistocene of Ukraine

Remains of small phasianid birds from several Pliocene and Pleistocene localities in the Northern Black Sea Region and Eastern Europe (Ukraine, Moldova, Poland, Czech Republic, and Hungary) are traditionally, based on similar proportions, assigned to Plioperdix pontica (Tugarinov, 1940). Our study of the bone material from Ukraine has shown that they in fact belong to several taxa of Galliformes. The remains from the localities of the Kuchurganian faunal assemblage (MN 14) can be attributed to Eurobambusicola turolicus Zelenkov, 2016, and supposedly to “Plioperdix” hungarica (Janossy, 1991). Plioperdix pontica is characterized by morphological similarity to modern Coturnix and is represented mainly by bone remains from the Odessa catacombs locality (upper part of Zone MN 15) and several localities of Zone MN 16, including Rebielice Krolewskie-2 (Poland). In the Middle Villafranchian localities (for example, Kotlovina; as well as Etulia-3, Moldova; Zone MN 17) remains of another unnamed form, which reliably differs from P. pontica in most skeletal elements, prevail. Previous descriptions and diagnoses of Plioperdix pontica, which were based on mixed bone materials of various taxa, are revised. Problems of the taxonomy of small Neogene–Pleistocene phasianids from the Northern Black Sea region and Eastern Europe are discussed.

A Widespread, Nearly Monospecific Silicified Coccoidal Microbiota from the Permian Of Brazil (AssistÊncia Formation, Irati Subgroup, Paraná Basin)

Well-preserved fossil microbiotas normally present relatively high taxonomic diversity, especially if the host-rock is distributed over a large area. Estimates of taxonomic diversity, however, require proper consideration of ontogenetic, taphonomic, and ecological influences on morphological variety. Otherwise, diversity may be overestimated. Chert in the Permian Assistencia Formation (Irati Subgroup, Parana Basin, Brazil) contains an abundant, well-preserved fossil microbiota that has been studied from seven localities distributed over about 500 km. Despite the great numbers of microfossils present, morphological analysis revealed a low apparent diversity. There is no evidence of filamentous microorganisms and the chroococcacean Gloeodiniopsis lamellosa is overwhelmingly dominant, accounting for 98.6% of counted individuals. In addition to G. lamellosa, only five taxa are recognized of which four are formally described: the chroococcaceans Cyanosarcinopsis hachiroi gen. et sp. nov. and cf. Coniunctiophycus sp. and two taxa considered incertae sedis: Myxococcoides sp. A (a probable cyanobacterium) and Myxococcoides sp. B (a possible delicate eukaryote). A unique but markedly different colony was designated as unnamed form (open nomenclature). Two hypotheses may explain the enigmatic absence of filaments: (i) environmental stress associated with hypersaline conditions that severely limited diversity or (ii) long-term optimal growth conditions for coccoidal cyanobacterial blooms due to sustained basin-wide eutrophic conditions.

Phosphatized microbial fossils from the lowest Cambrian of South China and their ecological and environmental implications for the Kuanchuanpu biota

The early Cambrian Fortunian-age Kuanchuanpu Formation exposed in the northwestern margin of South China is well known for recording unique aspects of the “Cambrian explosion”, notably the coexistence of Small Shelly Faunas and soft-bodied meiofaunas. Although microorganisms, both primary producers and decomposers, are important biotic components of marine ecosystems in which they play a crucial ecological role in matter cycling and energy flow, Cambrian microbial records have not been brought into attention so much as their intimately associated faunas. To extend these records here we report a diverse assemblage of cellularly preserved microbial fossils from cherts of the Kuanchuanpu Formation. Nine species comprising six genera and two undescribed taxa have been identified. Among taxa interpreted as primary producers, are Gloeodiniopsis and unnamed form B that are morphologically analogous to coccoidal chroococcacean cyanobacteria, and Megathrix and Siphonophycus to filamentous oscillatoriacean cyanobacteria. In contrast, co-occurring members of endobiotic Endoconchia ? are inferred to be biodegraders. The high preservational fidelity of this microbial assemblage is here documented by use of optical microscopy, scanning electron microscopy, energy dispersive spectrometry, back-scattered electron microscopy and Raman spectroscopy. These analyses results demonstrate that the microbial fossils were organic remains (Kerogen) permineralized by pre-decay phosphatization and then sealed within the encompassing siliceous matrix. This mode of fossilization differs from typical chert-embedded silica-permineralized Proterozoic microfossils in the presence of apatite permineralization, which is regarded as a response to the phosphogenic event during the Neoproterozoic-Cambrian transition.

Two New Cryptic Bat Species within the Myotis nattereri Species Complex (Vespertilionidae, Chiroptera) from the Western Palaearctic

The Myotis nattereri species complex consists of an entangled group of Western Palaearctic bats characterized by fringing hairs along the rear edge of their uropatagium. Some members are relatively common while others are rare but all forms are morphologically very similar and their taxonomy is unresolved. Recent studies based on different molecular markers have shown that several major and unexpected lineages exist within this group of forest-dwelling bats. All the mitochondrial and nuclear markers tested to date have shown that these major lineages evolved as fully independent and coherent units and therefore each qualifies as distinct species. In the absence of proper morphological diagnosis, these lineages are informally referred to in the literature under different names. We explore here the external and craniodental variation of these lineages. Although all morphological measurements were overlapping between these lineages, we show that lineages can be completely discriminated in a multivariate morphometric space. Consistent with previous molecular reconstructions, these four major lineages represent two pairs of related species, each represented by a named species (Myotis nattereri s. str. and M. escalerai, respectively) and by unnamed forms (Myotis sp. A and Myotis sp. B, respectively). Herein we describe formally these two unnamed forms to clarify the taxonomy within this species complex. This new taxonomic view has important implication for the protection of these species, as three of the four taxa must now be considered as range-restricted species in need of conservation actions.

Organic-walled microfossils from the late Mesoproterozoic to early Neoproterozoic lower Shaler Supergroup (Arctic Canada): Diversity and biostratigraphic significance

The diversification of acritarchs (organic-walled vesicular microfossils of unknown affinity), filamentous, and multicellular microorganisms, happened during a time of profound environmental, biological, and ecological change. The Mesoproterozoic to Neoproterozoic transition is a key interval, notably for eukaryotic organisms. New assemblages of organic-walled microfossils from the ca. 1230 Ma to 900 Ma lower Shaler Supergroup of Arctic Canada record an impressive diversity, including macroscopic compressions of Chuaria circularis and numerous unambiguous eukaryotic taxa. The index taxon Trachyhystrichosphaera aimika co-occurs with eukaryotic taxa hitherto reported only from earlier (Dictyosphaera, Gigantosphaeridium, Satka favosa – sensu Javaux and Knoll, 2016) or later (Microlepidopalla) time intervals. Five new taxa, comprising the spheroidal acritarchs with inner wall sculpture Nunatsiaquus cryptotorus n. gen., n. sp. and Daedalosphaera digitisigna n. gen., n. sp.; the acanthomorphs (spiny acritarchs) with regularly distributed processes Herisphaera arbovela n. gen., n. sp. and Herisphaera triangula n. sp.; and the process-bearing multicellular Ourasphaira giraldae n. gen., n. sp.; are reported, along with three unnamed forms. Collectively, these remarkable microfossils (63 taxa, including 25 eukaryotic forms) demonstrate the greatest diversity of eukaryotes ever recorded for this time interval.

Slight Exaggeration by Adam Zagajewski

FEATURED REVIEW Adam Zagajewski Slight Exaggeration Trans. Clare Cavanagh. New York. Farrar, Straus & Giroux. 2017. 275 pages. Slight Exaggeration announces itself playfully , in a faithful translation of the Polish opening: “I won’t tell all regardless.” “I tak wszystkiego nie opowiem” answers an unuttered promise to tell more, presumably, than we have already got—but even so (“I tak”), this will be no tell-all confession. Is this an indirect commentary on Adam Zagajewski’s international fame or perhaps on the autobiographical nature of his writing, letting us know that it may conceal as well as reveal? Or, perhaps, is he calling attention to our late-contemporary, postrecession, realityshow -fueled infatuation with having it all and telling it all? This may be reading too closely. But Zagajewski himself enjoys careful rethinking . Readers of his previous prose works— especially Two Cities, Another Beauty, and A Defense of Ardor—will recognize some familiar themes in this new book (originally published in Polish in 2011) and will also recognize that these themes will never be exhausted; his intellectual conundrums can never be solved. Zagajewski’s thinking thrives on traveling through cycles of reconsideration. He picks up a topic, pushes it forward, lets it go, and presently finds it again. In a beguilingly modest admission, he claims that even as a student of philosophy, he was never a true philosopher , lacking the talent for ironclad logic and absolute rationality. Precisely for this reason, we should not expect linearity from Slight Exaggeration. Instead, this is a book in search of a form. Too straightforward to be branded belles lettres, it is too digressive to be called an exposition or even an autobiography, the genre to which it is closest. Its miniatures (anecdotes, thoughts, impressions) likewise cannot be called essays. Zagajewski relaxes into this unnamed form, opening his sections conversationally—“Let’s return to” this, “But once more on” that. The mature poet clearly relishes the stylistic liberty he allows himself, and here lies much of the book’s charm: even as it ambles along its meandering path, its author keeps a close eye on the “big” themes that guide him. Indeed, it is a relief to have a contemporary World Literature in Review Conor O’Callaghan Comes Alive Verse, page 84 Aminatta Forna’s Redemptive Happiness Fiction, page 70 Hilde & Ylva Østby Plumb the Hippocampus Miscellaneous, page 90 66 WLT NOVEMBER–DECEMBER 2018 author so openly show us how his mind works, with no pretense of academic objectivity or absolute correctness. Chief among these themes is the author’s relation to his own past. Longtime readers will recognize Zagajewski’s enduring obsession with Lvov. A word for first-time readers: the Zagajewski family was forcibly resettled shortly after the poet’s birth in 1945, when the borders of Poland were redrawn after World War II. Poland “lost” Lvov (now called Lviv), a city in presentday Ukraine known as a cultural capital, and “gained” Gliwice, a rather less inspiring industrial town near the German border, one soon filled with resettled Lvovians. The Zagajewskis mourned the loss of their home city deeply. Their mythology of the lost home was passed down to Adam, whose most famous poem may be “To Go to Lvov.” Now, he knows very well that this is a private myth, and the facts of history only partially explain the workings of human psychology. He even relates an anecdote in which the strength of this myth creates a rift between him and his friends while visiting Lvov—friends who, he realizes, cannot participate in the myth, just as we cannot either. And he allows for a context of other displacements—geographic, socioeconomic, cultural—to situate that of his family, which helps gain further readerly empathy (because how many of us have no context of displacement, however oblique?). Here he catches us off guard by stating, “I didn’t suffer[;] I was an observer , not an emigrant,” since after all “displacement isn’t inherited, or perhaps it’s only passed on vestigially.” Perhaps. And perhaps not. This “vestigial” inheritance is vigorous enough to inform nearly all of Zagajewski’s writing. And it is crucial to understanding his persistent sense of inbetweenness : “I’m not an exile...

New material of scalidophoran worms in Orsten-type preservation from the Cambrian Fortunian Stage of South China

AbstractScalidophoran worms diversified in the Cambrian Fortunian, as indicated by recent reports from this stage, with two described species and two more unnamed forms exclusively from Orsten-type Lagerstätten yielding three-dimensionally phosphatized fossils. Here, we report new material of scalidophoran worms in Orsten-type preservation from the Cambrian Fortunian Xinli section in northern Sichuan Province, South China. At least five forms of scalidophoran worms were recovered from this location, includingEokinorhynchus rarusZhang et al., 2015 and four unnamed taxa—Forms A, B, C, and D. Co-occurring disassociated spinose small shelly fossils might also be isolated cuticular elements of these early scalidophoran worms. The ontogeny ofEokinorhynchus rarusis revised. Forms A, C, and D are assigned to total-group Scalidophora to indicate their uncertain positions within Scalidophora, while Form B might be a close relative ofEokinorhynchus rarus. The current work highlights the significance of Orsten-type Lagerstätten in uncovering the morphology, ontogeny, and taxonomy of early Scalidophora and Cycloneuralia, made particularly available by the new finds in China.

A new species ofRedudasys(Gastrotricha: Macrodasyida: Redudasyidae) from the United States

Abstract A new species of Redudasys (Macrodasyida: Redudasyidae) is described from Texas and Oregon, U.S.A. A single Texas specimen was reported (but not formally described and named) in 2014 from an artesian outflow in Spring Lake, San Marcos, Texas. The Texas specimen provided the first record of Redudasys from outside Brazil. Fifteen specimens were found and studied in 2015 and 2016 from sand pockets among boulders in the Little Nestucca River, near Pacific City, Oregon. Redudasys neotemperatus n. sp. is morphologically and genetically distinguishable from Redudasys fornerise Kisielewski, 1987a, the only formally described species in the genus up until now, and morphologically distinguishable from “Redudasys sp.”, an unnamed form reported by Garraffoni et al. in 2010 without genetic information. The Texas and Oregon specimens agree well morphologically and genetically.

Microchoerus hookeri nov. sp., a new late Eocene European microchoerine (Omomyidae, Primates): New insights on the evolution of the genus Microchoerus

The study of Eocene primates is crucial for understanding the evolutionary steps undergone by the earliest members of our lineage and the relationships between extinct and extant taxa. Recently, the description of new material from Spain has improved knowledge of European Paleogene primates considerably, particularly regarding microchoerines. Here we describe the remains of Microchoerus from Sossís (late Eocene, Northern Spain), consisting of more than 120 specimens and representing the richest sample of Microchoerus from Spain. This primate was first documented in Sossís during the 1960s, on the basis of scarce specimens that were ascribed to Microchoerus erinaceus. However, the studied material clearly differs from M. erinaceus at its type locality, Hordle Cliff, and shows some characters that allow the erection of a new species, Microchoerus hookeri. This new species is characterized by its medium size, moderate enamel wrinkling, generally absent mesoconid and small hypoconulid in the M1 and M2, single paracone in the upper molars and premolars and, particularly, by the lack of mesostyle in most M1 and M2, a trait not observed in any other species of Microchoerus. Some specimens from Eclépens B (late Eocene, Switzerland), determined previously to be Microcherus aff. erinaceus, are also ascribed to M. hookeri. M. hookeri represents the first step of a lineage that differentiated from Necrolemur antiquus and, later, gave rise to several unnamed forms of Microchoerus, such as those from Euzet and Perrière, finally leading to M. erinaceus. This discovery sheds new light on the complex evolutionary scheme of Microchoerus, indicating that it is most probably a paraphyletic group. A detailed revision of the age of the localities containing remains of Microchoerus and the description of the still unpublished material from some European localities, are necessary to clarify the phylogenetic relationships among the members of this microchoerine group.

Tianzhushania spinosa and other large acanthomorphic acritarchs of Ediacaran Period from the Infrakrol Formation, Lesser Himalaya, India

Covering a time span from Ediacaran (base of Blaini pink carbonates) to Early Cambrian (base of Tal Group), the Krol belt in the Lesser Himalaya (India), occurs as a series of synclines from Solan, Himachal Pradesh in the north-west to Nainital, Uttarakhand in the south-east. Various lithostratigraphic divisions of this belt reveal many palaeobiological entities, namely cyanobacteria, algae, acritarchs, small shelly fossils and trace fossils. Globally, large acanthomorphic acritarchs of the Ediacaran Period are used as significant biostratigraphic tools for global correlation. In the Krol belt, reports of acanthomorphic acritarchs from the Infrakrol and Krol ‘A’ formations of the Krol Group have further supported this notion. This paper reports well-preserved microfossils including acanthomorphic acritarchs, sphaeromorphic acritarchs, coccoids namely Tianzhushania spinosa, T. polysiphonia, Papillomembrana compta, Schizofusa sp., Gloeodiniopsis lamellosa, Sphaerophycus medium, and the unnamed forms A, B and C from the chert nodules of the Infrakrol Formation exposed in the Nainital Syncline of the Kumaun Lesser Himalaya. A biostratigraphic correlation based on acanthomorphic acritarchs suggests that the Infrakrol Formation is coeval to the lower Tianzhushania assemblage zone of the Doushantuo Formation of south China. Tianzhushania and Papillomembrana are significant additions to the previous record of the Ediacaran acanthomorphic acritarchs from the Lesser Himalaya of India and provide an independent evidence for construction of both biozonation scheme and paleogeography.

日本産ナガニシ属の研究 V：追加種，未記載種と考察

日本産ナガニシ属の研究 V：追加種，未記載種と考察

A biomechanical analysis of the early eukaryotic fossil Valeria and new occurrence of organic-walled microfossils from the Paleo-Mesoproterozoic Ruyang Group

The Paleo-Mesoproterozoic Ruyang Group of North China hosts early eukaryotic fossils such as Dictyosphaera, Shuiyousphaeridium, and Valeria, and thus offers valuable insights into the early evolution of single-celled eukaryotic life. In this paper, we report several additional forms of organic-walled microfossils from the Ruyang Group, including Plicatidium latum, Spiromorpha sp., and an unnamed form. V. lophostriata from the Ruyang Group is investigated using transmitted light microscopy, scanning electron microscopy, transmission electron microscopy, and biomechanical analysis. V. lophostriata is reconstructed as a spherical vesicle with two hemispherical halves bearing concentric striations resembling latitudinal circles. The formation of striations could be explained using the Belousov-Zhabotinsky reaction model or the Turing reaction-diffusion model. A biomechanical analysis using the thin-walled spherical pressure vessel model suggests that the concentric striations of V. lophostriata may have functioned as a mechanism to guide biologically programmed excystment through medial split. Our analysis provides essential paleontological data to better understand the functional biology and life cycles of early eukaryotes such as Valeria.

New aristonectine elasmosaurid plesiosaur specimens from the Early Maastrichtian of Angola and comments on paedomorphism in plesiosaurs

AbstractNew elasmosaurid plesiosaur specimens are described from the Early Maastrichtian of Angola. Phylogenetic analyses reconstruct the Angolan taxon as an aristonectine elasmosaurid and the sister taxon of an unnamed form of similar age from New Zealand. Comparisons also indicate a close relationship with an unnamed form previously described from Patagonia. All of these specimens exhibit an ostensibly osteologically immature external morphology, but histological analysis of the Angolan material suggests an adult with paedomorphic traits. By extension, the similarity of the Angolan, New Zealand and Patagonian material indicates that these specimens represent a widespread paedomorphic yet unnamed taxon.

Ediacaran acanthomorphic acritarchs from the Outer Krol Belt, Lesser Himalaya, India: Their significance for global correlation

Large acanthomorphic acritarchs have been previously reported from the Ediacaran successions of the Pachmunda and Krol Hill synclines in the Outer Krol Belt of Lesser Himalaya, India. Thin sections of chert from Krol ‘A’ Formation in Khanog and Rajgarh synclines, Outer Krol Belt, record an equally well developed and diversified assemblage of Ediacaran large acanthomorphic acritarchs. This assemblage contains specimens belonging to seven genera and ten species, identified as: Appendisphaera fragilis, A. grandis, Asterocapsoides sp. A, Asterocapsoides sp. B, Cavaspina acuminata, C. basiconica, Eotylotopalla dactylos, Knollisphaeridium sp., Papillomembrana sp., and Weissiella cf. grandistella. It also contains five unnamed forms, viz. A, B, C, D, and E. The Krol acritarch assemblage shows a close resemblance with the Upper Doushantuo or Tanarium anozos–Tanarium conoideum assemblage of China. However, the absence of biostratigraphically important markers such as Tanarium anozos and T. conoideum from the Krol assemblage, so far, makes it difficult to establish a definite biostratigraphic correlation between the two assemblages. The current observations from this new locality provide additional data for regional and global biostratigraphic correlation, and significantly increase the purview of Ediacaran sequences for global biostratigraphic zonation.

The oldest rhynchosaur from Argentina: a Middle Triassic rhynchosaurid from the Chañares Formation (Ischigualasto–Villa Unión Basin, La Rioja Province)

Rhynchosaurs first appear in the Early Triassic fossil record and flourished during the late Carnian as the dominant members of several assemblages worldwide. In Argentina, the rhynchosaur record is currently restricted to the Ischigualasto Formation of late Carnian–earliest Norian age. Recent fieldwork in the new locality of Brazo del Puma, in the lowermost levels of the Chanares Formation, yielded three rhynchosaur tooth-bearing bones, which were collected five metres above the contact with the underlying Tarjados Formation. The most complete specimen is the posterior end of the alveolar region of a left dentary. The dentary possesses densely packed tooth rows on the lingual surface and medial half of the occlusal surface, showing longitudinal Zahnreihen. The teeth of the occlusal surface are worn flat and those of the lingual surface are organized in multiple rows, supporting the referral of the specimen to Rhynchosauridae. In addition, the dentary teeth are conical to mesiodistally compressed, resembling the condition observed in hyperodapedontines. The rhynchosaur remains reported here are the oldest collected in Argentina and among the oldest in South America, together with an unnamed form from Brazil. The new rhynchosaur specimens come from levels in which dicynodonts are numerically dominant, whereas cynodonts are considerably less abundant. Accordingly, the specimens reported here bolster faunal differences within the Chanares Formation and add a new faunal component to this already diverse vertebrate assemblage.