Hasil untuk "Paleontology"

Soichi Osozawa

ABSTRACT Angiospermae radiation is widely recognized as a mid‐Cretaceous event, but the adaptive radiation of Asarum and Viola as spring ephemerals also occurred during the Quaternary. To better understand the evolution of Angiospermae through geological time, a robust and well‐calibrated timetree for Spermatophyta was constructed. The Angiospermae topology was aligned with the APG (Angiosperm Phylogeny Group) system, although node dates tend to be overestimated in recent mega‐trees compared to those in this study. An exponential increase in the base substitution rate in recent geologic time was also revealed through the use of an alternative dating function in BEAST (Bayesian Evolutionary Analysis Sampling Trees) v1.10.4, followed by a presumed increase in the mid‐Cretaceous. These events are thought to correspond to the Angiospermae radiations at the species level during the Quaternary and at the order level during the mid‐Cretaceous. One possible cause of the recent increase in substitution rates and subsequent radiations, including those of Asarum and Viola, could be the proliferation of C4 grasses, a reduction in atmospheric CO2, and the onset of the Quaternary glacial period. Plant evolution has drastically altered Earth's environments, which, in turn, have influenced evolutionary processes. The mid‐Cretaceous event may have been driven by co‐radiation with herbivorous beetles, although beetles also include species with non‐herbivorous habits.

Yang Zhao, Jordan Bestwick, Jan Fischer et al.

Abstract Chondrichthyan egg capsules, fossil and recent, have a taxonomical significance that can provide important insights into the occurrence and reproductive strategy of their producers. However, the rare occurrence of fossil capsules and their sometimes difficult identification hinder our understanding of their systematics and significance. Laffonia from the Late Jurassic of Switzerland and its probable junior synonym, Pseudocaudina, from the Late Jurassic lithographic limestones of southern Germany, have been interpreted in a variety of ways including as a fructification of a plant, a possible egg capsule of a shark or ray, a presumed holothurian, a possible actinarian, or even a ctenophore. Here, we redescribe the holotype of Laffonia, which has a fusiform body that is ornamented with over seven longitudinal ribs and two narrow striated flanges at its lateral edges. These morphological features are incompatible with a diploblast or echinoderm affinity, but highly resemble the characteristics of certain holocephalan egg capsules in several respects. Our phylogenetic analysis places Laffonia within a group containing the Carboniferous fossil capsules Crookallia and Vetacapsula, as well as recent chimaerid capsules. Thus, we suggest that the Mesozoic Laffonia represents an intermediate morphotype between the Carboniferous species and extant chimaerid capsules. Laffonia is the only known fossil chimaerid-like capsule from the Mesozoic so far, which offers novel insights into the morphology and evolution of holocephalan egg capsules.

Natalia Jagielska

Gregory S. Paul 2022. The Princeton Field Guide to Pterosaurs. 184 pp. Princeton University Press. ISBN 978-0-691-18017-5. Price USD 29.95 (hardcover).

George Kontakiotis, Assimina Antonarakou, Dmitry A. Ruban

Research into modern oceans, seas, and their coastal zones, as well as marine ecosystems, provides valuable information for deciphering the geological dynamics [...]

Xiaolin Wang, Kamila L. N. Bandeira, Rui Qiu et al.

Abstract The Early Cretaceous Hami Pterosaur Fauna in Northwest China preserves a large number of specimens of the sexually dimorphic pteranodontoid pterosaur Hamipterus tianshanensis, including 3D eggs and embryos. During the last decade, several more fossils have been collected in this area, including three somphospondylan sauropod specimens. The first is Silutitan sinensis gen. et sp. nov., which consists of an articulated middle to posterior cervical vertebrae series. The second, Hamititan xinjiangensis gen. et sp. nov., consists of an incomplete articulated caudal sequence that could be assigned to lithostrotian titanosaurs based on the strongly procoelous caudal vertebrae with lateral concave surface, as well as marked ventrolateral ridges. The third specimen consists of four sacral vertebral elements, apparently unfused, with exposed camellate internal bone and regarded as somphospondylan. Cladistic analyses based on different datasets recovered Silutitan sinensis as an euhelopodid closely related to Euhelopus and Hamititan xinjiangensis as a titanosaur. Besides the pterosaur Hamipterus and one theropod tooth, these dinosaurs are the first vertebrates reported in this region, increasing the diversity of the fauna as well as the information on Chinese sauropods, further supporting a widespread diversification of somphospondylans during the Early Cretaceous of Asia.

DENIS GERAADS, SAMIR ZOUHRI

We describe here the first definite representative of the subfamily Elasmotheriinae in North Africa. It comes from the upper Miocene site of Skoura near Ouarzazate, on the southern slope of the Central High Atlas in Morocco. It consists of a virtually complete skull with articulated mandible and a few fragmentary postcranial remains, making it by far the best known elasmotheriine from the African late Miocene. We assign it to a new taxon, Eoazara xerrii gen. et sp. nov. The skull is characterized by long nasal bones indicating a strong horn and long, anteriorly expanded, edentulous pre-maxillae. Compared to other Rhinocerotidae, the face is moderately elongated; the lower incisors are of medium size; and the premolar row is short. The upper molars have a strongly pinched protocone, a long antecrochet, and an unexpanded central valley. Eoazara xerrii gen. et sp. nov. is at a lower evolutionary grade than the Chinese species of Ningxiatherium and Parelasmotherium, but probably comparable to the very incomplete remains from the East African late Miocene forms. We regard Eoazara as a member of a chiefly Eurasian clade, rather than as a survivor of a hypothetical African elasmotheriine branch. Parsimony analysis confirms the monophyly of the Elasmotheriinae, but that of the remaining Rhinocerotidae is questionable.

Qian Wu, Qian Wu, Qian Wu et al.

As key components of the tetrapod pectoral girdle, the scapula and coracoid have played a significant role in the evolution of forelimb locomotion among terrestrial vertebrates. The transition from a rigid fused scapulocoracoid in ancestral non-avian theropods to a presumably more flexible separated scapula-coracoid in early birds is considered to be one of the key morphological transitions related to the rapid refinement of flight. In most Mesozoic birds (e.g., Enantiornithes and Ornithuromorpha) and crown birds the scapula and coracoid are separate (unfused), with few exceptions (e.g., flightless paleognaths). In contrast, in Confuciusornis, a basal pygostylian from the Early Cretaceous Jehol Biota known from thousands of specimens, the scapula and coracoid remain plesiomorphically fused. This raises questions regarding the influence of shoulder girdle architecture on the early evolution and refinement of avian flight. The paravian scapula-coracoid joint has never previously been investigated using histology, and thus joint morphology has only been inferred superficially. In order to better understand the evolution of this joint in Mesozoic birds, we make the first histological study of the scapulocoracoid glenoid joint in Confuciusornis. The results demonstrate that the scapula and coracoid both consist of cancellous and compact bone, with both fibrolamellar and parallel-fibered structure. A thin layer of calcified cartilage is present on the glenoid fossa surface, representing remnants of the articular surface for the humerus. Both histology and computed tomography reveal that the scapulocoracoid of Confuciusornis is fully fused, forming a synostosis. Humeral histology suggests the studied individual was nearing completion of its first year of growth, suggesting the Confuciusornis scapulocoracoid fused before skeletal maturity was achieved, as in flightless paleognaths, whereas in the plesiomorphic condition fusion occurs late in ontogeny. We hypothesize the fused scapulocoracoid of Confuciusornis is secondarily evolved and suggest the primary factor responsible for this morphology may have been a decrease in mechanical stimulation at the glenoid of Confuciusornis relative to other volant birds, linked to the unique flight style of this taxon. Further investigation into the histology of the glenoid joint in other Mesozoic paravians and extant birds will help to clarify the morphological transition of the scapula-coracoid joint in early avian evolution.

THOMAS LAVILLE, CHRISTOPHER. P. A. SMITH, MARIE-BÉATRICE FOREL et al.

Thylacocephala (Euarthropoda: Eucrustacea?) is a group of enigmatic fossil euarthropods, known from at least the Silurian to the Cretaceous. The Triassic is considered to be the period during which thylacocephalans were the most diversified with 17 species reported from 19 localities in nine countries. However, Thylacocephala were assumed to be rare during the Early Triassic until recent discoveries in Japan, Nevada and Idaho, U.S.A.       Our study focuses on thylacocephalans from the Early Triassic, especially from Madagascar and Idaho. The revision of previously known taxa from Madagascar provides new important information. A new kind of ornamentation is reported for Paraostenia ambatolokobensis nov. comb., previously assigned to Ostenocaris ambatolokobensis. In addition, Ankitokazocaris acutirostris and Paraostenia ambatolokobensis are only the third and fourth thylacocephalan taxa for which possible cephalic appendages are described.  New occurrences of Thylacocephala in Nevada and Idaho, U.S.A., lead to the description of one new taxon and to the reassignement of Parisicaris triassica to Ankitokazocaris triassica nov. comb. Those occurrences provide a significant contribution to the knowledge of Thylacocephala taxonomic diversity and geographic distribution during the Early Triassic. An important revision of Early Triassic thylacocephalan taxa from Japan and China is also performed, including Ankitokazocaris chaohuensis, Ankitokazocaris parva nov. comb., Ankitokazocaris utatsuensis nov. comb. and Paraostenia sp. Overall, the taxonomic diversity of Triassic thylacocephalans has likely been slightly over-estimated (17 species before, 15 now). However, the Triassic represents the richest period in terms of thylacocephalan-bearing outcrops (19 localities from nine countries).

Bradley McFeeters

An unusual mid-cervical vertebra belonging to a large spinosaurid from the Cenomanian Kem Kem Group of Morocco is described. It is compared to the characteristic morphology of each reconstructed cervical position in Spinosaurus aegyptiacus, based on a recent composite reconstruction that incorporates most previously referred material from this unit. Rather than conforming to any of the previously identified cervical positions in its morphology, the specimen displays a unique combination of mid-cervical characters, with the relatively compact centrum suggesting a position as C4, and the form of the neural arch laminae suggesting a position as C5 or C6. Furthermore, it displays two characters that are previously unknown in spinosaurid mid-cervicals from the Kem Kem Group: a rounded hypapophyseal tuberosity that is not continuous with a ventral keel, and a moderately developed, dorsally oriented epipophysis that does not overhang the postzygapophysis posteriorly. The diagnostic value of positionally variable cervical vertebral characters in spinosaurid systematics is discussed. Although limited, the new data could lend support to the controversial hypothesis that two spinosaurid taxa are represented in the Kem Kem Group.

Xiaolong Yuan, Xiaolong Yuan, Fanwei Meng et al.

Polyhalite occurrence in the Kunteyi Playa in the Qaidam Basin has been known for many years. However, the genetic mechanism of this deposit remains unclear. In this study, a typical section in the playa depocenter is selected to study the polyhalite mineralogy combined with the homogenization temperature and composition of halite fluid inclusions in shallow evaporitic strata. The results show that 1) the main evaporite minerals in the strata are halite and polyhalite; no common gypsum is found; 2) analyses of homogenization temperatures of halite fluid inclusions indicate that a higher temperature is needed for polyhalite generation compared with other saline minerals; and 3) the fluid inclusion chemical analysis shows that they are sulfate-type minerals with a shortage of Ca. Thus, it can be concluded that the formation of polyhalite is not related to gypsum replacement, and deep oilfield brines may provide a Ca source and a higher temperature for polyhalite formation, where the mixing and interaction occurred between K- and Mg-enriched sulfate brines and deep Ca-enriched brines under the control of climate and tectonics in the study area. While most polyhalite was generated natively, some formed during secondary generation, which was potentially related to replacement with carnallites or sylvites.

Claudine Abegg, Jocelyne Desideri, Olivier Dutour et al.

Whilst undertaking a paleoepidemiological study of the neolithic and Bell Beaker culture populations of western Switzerland, a strange case was uncovered in the necropolis of Barmaz II. Individual R16 is only represented by three cranial fragments, two of them appearing grossly misshapen. Under different circumstances, the pathologies might have gone unreported, however since the project within which the analysis took place aimed to record all pathological lesions observed in the populations of neolithic western Switzerland, it seemed amiss not to pursue the case further. With the purpose of bringing a plausible explanation to the lesions observed, CT-scans were carried out, and compared to a healthy anatomical specimen. The results of this investigation are detailed below, as well as the differential diagnosis proposed.

M. Wisshak, L. Hüne

<p>A single specimen of an enigmatic new attachment etching, together with an unknown calcareous encruster partly preserved in situ, has been identified on a belemnite rostrum from the Marnes de Dives Formation (Callovian, Middle Jurassic) of the Falaises des Vaches Noires in Normandy, France. The trace fossil, here established as the new ichnotaxon <i>Circumpodichnus serialis</i> igen. et isp. n., is a uniserial arrangement of very shallow depressions, oval to fusiform in outline, with peripheral pouches and central pits.</p> <p>The trace maker has a morphology unlike any other known calcareous epibiont, fossil or recent, and is consequently described as the new microproblematicum <i>Circumpodium enigmaticum</i> gen. et sp. n. Its calcitic skeleton is composed of a chain of segments with perforate basal and lateral walls, anchored to the attachment trace in the substratum by vertical protrusions in the centre and feet-like protrusions in the periphery. The hypothetical upper wall of the segments was either organic-walled and has decayed or it was calcitic and has been abraded.</p> <p>Based on morphological criteria and the capacity to bioerode, <i>C. enigmaticum</i> can best be compared to encrusting bryozoans and foraminiferans. Candidate bryozoans are aberrant arachnidiid ctenostomes, early cheilostomes, or stomatoporid cyclostomes. Among the foraminiferans, webbinellid or ramulinid polymorphinids are closest in their characters. In addition, tintinnid or folliculinid ciliophorans are considered as an alternative interpretation, and similarities to the Palaeozoic microproblematicum <i>Allonema</i> are discussed.</p>

Magdalena Borsuk-Białynicka

Three morphotypes of the fifth metatarsal (MttV), one of the most informative bones of the postcranium, have been described herein from the Early Triassic karst deposits of the Czatkowice locality (Southern Poland). Two of them have been assigned to a basal archosauriform Osmolskina czatkowicensis and a basal lepidosauromorph, Sophineta cracoviensis, respectively, while one is undetermined saurian. Two morphological categories of the hooked fifth metatarsals recognized from this assemblage account for two different solutions to the problem of improvement of locomotion. A strongly inflected (sensu Robinson 1975) MttV shaft consists of two parts, a distal one lying on the ground in a plantigrade manner and a proximal one bent at an angle to get align with the ventral surface of the crus and proximal tarsus. In contrast, a straight shaft of the hooked MttV, suggests its subvertical life position and thus a digitigrade foot stance. The hooking of the fifth metatarsal, that is currently accepted saurian synapomorphy, appeared in phylogeny in a primitive state referred to herein as a neckless type: with neither a neck-shaped articular protrusion for the fourth distal tarsal nor a directly medial orientation of the articular facet. A derived long-necked type with protruding arricular part and more directly medial orientation of the articular facet appeared, at various stages of further phylogeny. A strong plantar–dorsal inflexion of the fifth metatarsal associated with a protrusion of lateral plantar tubercle, dates from a directly pre-lepidosaurian stage of evolution.

G. Arratia, K. A. González-Rodríguez, C. Hernández-Guerrero et al.

A new genus and species – <i>Motlayoichthys sergioi</i> (ZooBank registration: urn:lsid:zoobank.org:pub:2C503741-2362-4234-8CE0-BB7D8BE5A236, urn:lsid:zoobank.org:act:EF5040FD-F306-4C0F-B9DA-2CC696CA349D) – from the Cretaceous (Albian-Cenomanian) of the Muhi Quarry, Hidalgo, central Mexico is assigned to the family Pachyrhizodontidae based on the presence of the inner premaxillary tooth and a few other cranial characters. Its unique suite of characters, that includes several autapomorphies supports its assignment as a new genus and species, such as the presence of a triangular head with three sides of similar lengths and with its deepest part at the level of the supraoccipital region; the lower jaw projecting anterior to the premaxilla; the ornamentation of cranial bones – especially those of the cheek region – consisting of fine longitudinal crests densely covering the bony surfaces; one or a few deep grooves on the mandibular teeth, which in addition bear acrodin tips ornamented with fine parallel striae; and the position of the dorsal fin, near the posterior margin of the cranium. <i>Motlayoichthys</i> n. gen., together with <i>Michin</i>, <i>Pachyrhizodus</i>, <i>Rhacolepis,</i> and <i>Notelops</i>, is part of the early radiation of pachyrhizodontoids during Albian times.

Zorov Yuriy N. , Kolesnik Alexander V. , Ocherednoy Aleksander K.

The paper presents unknown or poorly investigated sites of the Middle and Late Paleolithic found under different circumstances along the southern coast of the Bay and in the delta of Don. Systematic research of the Paleolithic of the Azov North-East and East Sea Littoral has been carried out since the 1930s. The considerable corpus of sites of the Early, Middle and Late Paleolithic is accumulated. It should be noted that the most of sites is discovered on the northern coast of Taganrog Bay and on the Lower Don. Until now, the southern coast of Taganrog Bay attracted attention of specialists in the Quaternary Period mainly because of good geological sections and monuments of paleontology. All the findings were collected on a surface. The most interesting collections of stone tools are collected near the villages of Margaritovo and Semibalki of the Azov region of the Rostov province. Findings of the Middle Paleolithic have analogies in complexes of so-called “Eastern Micoquien” of the Northern Azov Sea Littoral. Findings of the Upper Paleolithic are similar to standards of Aurignac technocomplex.

EDUARDO GARZANTI, MARIO GNACCOLINI, FLAVIO JADOUL

The mixed terrigenous-carbonate-evaporitic  S.Giovanni Bianco  Formation  and dolomitic Campolungo  Tongue  (upper part of the Breno Formation),  generally 2OO  to  3OO  m thick, are assigned  to the Late Carnian.  They  respectively  overlie lagoonal limestones  (Gorno  Fm.)  and peritidal  carbonates  (Annunciata Member of the Breno Fm.), and underlie  intraformational  breccias  and recrystallized  limestones  (Castro Fm.). Recognition of an unconformity,  ascribed  to a relative  fall of sea-level (sequence  boundary), allowed  us to subdivide the Upper  Carnian  succession  into two parts. ln the lower part (SGBL),  six lithosomes  were recognized. Red  to green  alluvial  clastics in the south-east  and south-west  pass northward  to mixed terrigenous-carbonate  coastal sediments  and finally to dolostones  deposited  in carbonate tidal flats. In the proximal sections  of the Brescia  Prealps,  renewed  north-westward  progradation  of alluvial redbeds  with  intercalated  calclithite conglomerates  points to a stage of teconic uplift. A distinct  increase  in quartz, representing a regional  petrographic  marker  followed  all  across Lombardy, indicates  deepening  of erosion  into the metamorphic wallrocks  of the volcanic  belt. A major hiatus  at the top of the SGB1  is best documented  in the northern  Presolana  area by a silcrete crust directly overlying  the Julian Annunciata Member of the Breno Formation.  In the Brembana  Valley area, the discontinuity occurs within  a greenish  siliciclastic  coastal  plain  succession, and may be traced at the top of a marker  interval of interbedded  reddish siltstones  and sandstones. The upper part (SGB2) consists  of four lithosomes. Greenish sandstones  and siltstones,  accumulating  in coastal  plains in  the south-west,  passed  northward  to mudrocks and dolostones.  In the southernmost  Camonica Valley  area,  mudrocks  are locally interbedded  with  calcarenites  containing  bored or pedogenized  lithoclasts ripped from the underlying sequence and varied  bioclasts,  restifiying to relatively  open shallow-marine conditions  during transgression. Next, thick gypsum  accumulated in coasral  salinas  barred  by locally oolitic  platform carbonates to the north. Rare sandstone lenses  occurring  in the Brembana Valley at the top of the unit conrain  exclusive rhyolitic  detritus,  indicating either  a terminal phase of explosive  volcanism  or erosion of older  felsic volcanic products.

Lüzhou Li, Qiang Li, Xiaoyu Lu et al.

The Early to Late Oligocene Propalaeocastor is the earliest known beaver genus from Eurasia. Although many species of this genus have been described, these species are defined based on very fragmentary specimens. Propalaeocastor irtyshensis from the Early Oligocene Irtysh River Formation in northwestern Xinjiang, China is one of the earliest-known members of Propalaeocastor. This species is defined on a single maxillary fragment. We revise the diagnosis of P. irtyshensis and the genus Propalaeocastor, based on newly discovered specimens from the Irtysh River Formation. The dental morphology of P. irtyshensis is very similar to other early castorids. The caudal palatine foramen of P. irtyshensis is situated in the maxillary-palatine suture. This is a feature generally accept as diagnostic character for the castorids. On the other hand, P. irtyshensis has two upper premolars, a rudimentarily developed sciuromorph-like zygomatic plate, and a relatively large protrogomorph-like infraorbital foramen. Some previous researchers suggested that Propalaeocastor is a junior synonym of Steneofiber, while other took it as a valid genus. Our morphological comparison and phylogenetic analysis suggest that Propalaeocastor differs from Steneofiber and is a valid genus. We also suggest that Agnotocastor aubekerovi, A. coloradensis, A. galushai, A. readingi, Oligotheriomys primus, and “Steneofiber aff. dehmi” should be referred to Propalaeocastor. Propalaeocastor is the earliest and most basal beaver. The origin place of Propalaeocastor and castorids is uncertain. The Early Oligocene radiation of castorids probably is propelled by the global climate change during the Eocene-Oligocene transition.

David A. Legg

A new taxon of marrellid marrellomorph Dyrnwynia conollyi gen. et sp. nov. is described from the Middle Ordovician (middle Darriwilian, Didymograptus artus Biozone) Llanfallteg Formation of Northern Pembrokeshire, Wales, UK. This taxon, represented by a single specimen, is characterised by the possession of mediolateral spines with tightly spaced secondary cephalic spines limited to their external margins and that decrease in size towards the distal tip. This is the first record of marrellid arthropods from Great Britain and only the fourth record from the entire Ordovician worldwide, which, given their current geographic and temporal distribution, indicates that marrellid arthropods may be more common in the fossil record than previously recognised.

Artur Chahud, Setembrino Petri

The Tatuí Formation, one of the Brazilian Paraná Basin geological units, is developed solely in the State of São Paulo, southeast Brazil. It is studied herein, through outcrops at the eastern border of the basin, which are siltstones and fine sandstones, interbedded with some coarse and conglomeratic sandstones. Published papers on its fossils are sparse, dealing with some groups but not involving the entire association. This paper deals with ichnofossils, arthropods (conchostracans, isopods, and indeterminate crustaceans), plants (pteridophytes and spermatophytes) and fish remains (scales and teeth of Actinopterygii and Sarcopterygii). Foraminifers and sponge spicules were reported in short communications without illustrations and from uncertain stratigraphic positions. The Tatuí Formation paleoenvironmental deposition evolved through three phases. The first contains only the euryhaline fossils in siltstone beds. The second phase is regressive, with continental fossils (conchostracans and plants) in massive or laminated siltstone beds and conglomerates. The third stage is transgressive with hummocky cross – stratification in sandstone and increasing salinity.   La Formación Tatuí (Pérmico Temprano, Cuenca del Paraná), Brasil: Consideraciones paleontológicas y paleoambientales   Resumen La Formación Tatuí es una unidad litoestratigráfica de la Cuenca del Paraná que aflora exclusivamente en el Estado de São Paulo, Brasil. En su borde nororiental está formada por limolitas y areniscas finas que poseen intercalaciones de areniscas gruesas y conglomeráticas. Este trabajo caracterizó en esta formación diversas evidencias de fósiles: huellas,  artrópodos (conchostracos, crustáceos isópodos e indeterminados), vegetales (helechos y fanerógamas) y restos de vertebrados (escamas y dientes de Actinopterygii y Sarcopterygii). Foraminíferos y espículas de esponjas fueron reportados en comunicaciones breves, entretanto, sin estar acompañado de ilustraciones y de sus posiciones estratigráficas. Tres fases de deposición permiten reconstruir el paleoambiente de la Formación Tatuí. En la primera fase hay presencia solamente de fósiles eurihalinas en limolitas. En la segunda fase, fósiles continentales (conchostracos y vegetales) que están presentes en camadas limolíticas masivas o laminadas y en conglomerados vinculados a una etapa regresiva. Finalmente, la tercera fase se caracteriza por una etapa transgresiva con la presencia de estratificación cruzada “hummocky” y aumento de la salinidad.