Abstract Silurian strata are well-developed in the northwest margin of Yangtze Platform. A total of 117 densely spaced argillaceous samples were taken from the Shenxuanyi Member, upper Ningqiang Formation to the lowermost Chejiaba Formation of the Majia section in northern Sichuan Province. The main aim of this study is to obtain chitinozoans to test whether Wenlock deposits are preserved here. A highly diverse and abundant chitinozoan assemblage is documented, including 21 species from six genera. This assemblage was then compared to contemporaneous chitinozoan assemblages reported from adjacent areas. This study proposes that Eisenackitina venusta (corresponds to the Pterospathodus celloni conodont Biozone) is of chronostratigraphical significance for discussing the Telychian of the Yangtze region. It is suggested that the Silurian upper red bed (lower part of the Shenxuanyi Member) in the study area is younger than the Xiushan Formation and can be correlated with the Huixingshao Formation of the Central Yangtze Platform. There are no index chitinozoan species near the Llandovery–Wenlock boundary that have been found in the upper part of the Shenxuanyi Member, and the updated chronostratigraphic framework suggests that it is Telychian-aged deposits.
Abstract Species that have persisted over millions of years have done so because they have been able to track peaks in an adaptive landscape well enough to survive and reproduce. Such optima are defined by the mean phenotypic values that maximize mean fitness, and they are predominantly functions of the environment, for example the sea temperature. The mean phenotypic values over time will thus predominantly be determined by the environment over time, and the trait history may be found in the fossil record. Here I use fossil data from four cases found in the literature, and show that adaptive peak tracking models give better results than alternative weighted least squares and directional random walk models. The model performances are compared by use of weighted mean squared errors and Akaike information criterion results.
Miguel Ángel García-Villafuerte, Gerardo Carbot-Chanona
Syninclusions are palaeontological resources that provide palaeoautoecological evidence of fossil species and information on the biological interactions between different organisms that were part of a past ecosystem. Although palaeautoecological interactions in amber have been documented worldwide, interactions between predators and potential prey are rare. Here, we documented the first evidence in Miocene Chiapas amber of predator-predator-prey interaction involving two spider species and one insect: the araneophagous “pirate spider” Mimetus sp., the Theridiidae spider Thymoites carboti, and gall flies (Cecydomiidae). The interaction between Mimetus sp. and T. carboti is documented as a possible case of araneophagy or opportunism. Also, the first evidence of a web built by some members of the Thymoites genus is presented. The taphonomic analysis of the amber piece indicated that they were all captured at the same time under the same resin flow.
Francesc Pérez-Peris, Jonathan M. Adrain, Allison C. Daley
Abstract Cheiruridae is one of the most diverse families of trilobites known from the Ordovician with 453 species assigned. Within Cheiruridae eight subfamilies (Acanthoparyphinae, Cheirurinae, “Cyrtometopinae”, Deiphoninae, Eccoptochilinae, Heliomerinae, Pilekiinae, and Sphaerexochinae) have historically been recognised. Insights about the evolution of the family and the relationships within and between subfamilies have been published. However larger scale phylogenetic hypotheses are needed in order to explore the monophyly, the basal structure, the deep nodes and the relationships of the subfamilies. Cheirurinae, Deiphoninae and “Cyrtometopinae” have historically been defined by various morphological features (e.g., anteroposterior constriction of the thoracic pleura, pleural furrow morphology, pygidial morphology) that differentiate them from the rest of Cheiruridae. However, the phylogenetic status of “Cyrtometopinae” is unclear owing to a lack of obvious synapomorphies. Here, we present phylogenetic analyses of Cheirurinae, Deiphoninae, and “Cyrtometopinae”. The results indicate that both Cheirurinae and Deiphoninae are monophyletic. “Cyrtometopines” are resolved as a paraphyletic grade at the base of Deiphoninae and Cyrtometopinae should be considered a junior subjective synonym of Deiphoninae. The new phylogenetic hypothesis reveals that paedomorphosis plays an important role in the evolution of Deiphoninae. Within Cheirurinae two major clades are identified, the ‘Ceraurus-like’ clade and the ‘Ceraurinella-like’ clade.
Serjoscha W. Evers, Kimberley E. J. Chapelle, Walter G. Joyce
Abstract Trionychid (softshell) turtles have a peculiar bauplan, which includes shell reductions and cranial elongation. Despite a rich fossil record dating back to the Early Cretaceous, the evolutionary origin of the trionychid bauplan is poorly understood, as even old fossils show great anatomical similarities to extant species. Documenting structural detail of fossil trionychids may help resolve the evolutionary history of the group. Here, we study the cranial and mandibular anatomy of Plastomenus thomasii using µCT scanning. Plastomenus thomasii belongs to the Plastomenidae, a long-lived (Santonian–Eocene) clade with uncertain affinities among trionychid subclades. The skulls of known plastomenids are characterized by unusual features otherwise not known among trionychids, such as extremely elongated, spatulate mandibular symphyses. We use anatomical observations for updated phylogenetic analyses using both parsimony and Bayesian methods. There is strong support across methods for stem-cyclanorbine affinities for plastomenids. The inclusion of stratigraphic data in our Bayesian analysis indicates that a range of Cretaceous Asian fossils including Perochelys lamadongensis may be stem-trionychids, suggesting that many features of trionychid anatomy evolved prior to the appearance of the crown group. Divergence time estimates from Bayesian tip-dating for the origin of crown Trionychia (134.0 Ma) and Pan-Trionychidae (123.8 Ma) constrain the evolutionary time span during which the trionychid bauplan has evolved to a range of < 11 million years. Bayesian rate estimation implies high morphological rates during early softshell turtle evolution. If correct, plastomenids partially fill the stratigraphic gap which results from shallow divergence times of crown cyclanorbines during the late Eocene.
Floian, Early Ordovician trilobites are systematically described and revised based on new material from the middle part
of the Duoquanshan Formation of the Shihuigou area, northern Qinghai Province, northwest China. The fauna that lived
on the shallow-water carbonate platform comprises three species belonging to two families, i.e., Tsaidamaspis diarmatus,
Zhiyia tsinghaiensis, and Liexiaspis sp. indeterminate. It exhibits a strong endemicity to the Olongbluk terrane. The new
isoteline genus Zhiyia is established on the basis of the material from the Olongbluk terrane and South China palaeoplate,
and is characterized by its: (i) almost obsolete cephalic and pygidial axial furrows; (ii) flattened anterior border
and narrow (sag., exsag.) occipital ring; (iii) bilobed hypostome with a shallow median notch and a small triangular
median projection; (iv) subsemicircular pygidium with wide pygidial axis and border. Faunal evidence indicates that the
palaeogeographic position of the Olongbluk terrane may have been situated closer to the South China palaeoplate rather
than the North China palaeoplate during the Floian.
Paleontology for conservation Human activities are leading to broad species and system declines. Prevention of such declines has led us to focus on either protection for species or protection for ecosystem function. Looking at past patterns of species and system change can help to inform our understanding of the long-term impacts of these strategies. Blanco et al. studied mammals from the last 21 million years on the Iberian Peninsula, finding long periods of functional stasis, even in the face of taxonomic variability (see the Perspective by Roopnarine and Banker). Functional ecosystems were more resistant to ecosystem collapse. Science, this issue p. 300; see also p. 237 Functional richness in past mammal communities increased ecosystem resilience. The study of deep-time ecological dynamics has the ability to inform conservation decisions by anticipating the behavior of ecosystems millions of years into the future. Using network analysis and an exceptional fossil dataset spanning the past 21 million years, we show that mammalian ecological assemblages undergo long periods of functional stasis, notwithstanding high taxonomic volatility due to dispersal, speciation, and extinction. Higher functional richness and diversity promoted the persistence of functional faunas despite species extinction risk being indistinguishable among these different faunas. These findings, and the large mismatch between functional and taxonomic successions, indicate that although safeguarding functional diversity may or may not minimize species losses, it would certainly enhance the persistence of ecosystem functioning in the face of future disturbances.
Human fossil discoveries in Java are anchored in the history of science and in Javanese culture. Looking back at the early steps of research is informative regarding the emergence of human paleontology and sheds light on the progressive understanding of natural factors and events involved in human evolution, a major chapter of it having been written in Southeast Asia. Java is part of the “Malay archipelago,” and its colonization by continental fauna and humans is closely related to the paleogeographic history of the Sunda shelf and to the geotectonic activity. Dispersals, exchanges with mainland, and insular endemism followed complex patterns which are only partly understood today. Stratigraphic sedimentary series are quite diversified throughout Java Island, and are present together with records offered by karstic fillings and river terraces. Combined stratigraphical, paleontological, and archaeological registers leads to the draft of a “storyline” that helps to identify research priorities in order to reach a better matching level between prehistory and the paleobiogeographical history of the archipelagos. One of the major issues that must be sorted out is an apparent linear evolution of Javanese Homo erectus, at odds with the record of repetitive exchanges with Asian mainland documented by the fauna. Such an entry point leads to numerous related questions, as for example human dispersals beyond the Wallace Line, the emergence of endemic forms, the possible coexistence of different forms of humankind, and the dissemination or isolation of cultural traditions.
Las dos instituciones más relevantes dedicadas a la promoción de las ciencias naturales en el sur de la provincia de Mendoza son el Museo de Historia Natural de San Rafael (MHNSR) (Departamento de San Rafael) y el Museo Regional de Malargüe “Jorge Luna” (MRM) (Departamento de Malargüe). La primera institución fue fundada en el año 1955 mientras que la segunda se erigió en el año 1973 y ambas se incorporaron a la órbita municipal en los primeros años de la década del ‘70 del siglo pasado. Estos museos han tenido un diferente desarrollo y proyección en lo que respecta a su actividad científica. Esto también se reflejó en el desarrollo de la paleoherpotología en el MHNSR con la incorporación de investigadores y becarios del CONICET acontecida a partir del año 2002. En el año 2006 se originó el Centro Regional de Investigación y Desarrollo Cultural, institución que desarrolló actividades paleontológicas en Malargüe principalmente entre los años 2006 y 2015. Con la reciente creación del Instituto de Evolución, Ecología Histórica y Ambiente, unidad ejecutora de doble dependencia CONICET y Universidad Tecnológica Nacional, los paleontólogos continuaron su desempeño en esta unidad sin dejar el MHNSR, donde se alojan las colecciones paleontológicas. En el MRM, las colecciones se encuentran tanto en el antiguo molino del casco de la estancia “La Orteguina”, edificación colindante, y en la sala de exposición de paleontología de dicho museo. Estas instituciones resguardan pequeñas colecciones de reptiles fósiles.
Abstract The Smithian–Spathian boundary (SSB) crisis played a prominent role in resetting the evolution and diversity of the nekton (ammonoids and conodonts) during the Early Triassic recovery. The late Smithian nektonic crisis culminated at the SSB, ca. 2.7 Myr after the Permian–Triassic boundary mass extinction. An accurate and high-resolution biochronological frame is needed for establishing patterns of extinction and re-diversification of this crisis. Here, we propose a new biochronological frame for conodonts that is based on the Unitary Associations Method (UAM). In this new time frame, the SSB can thus be placed between the climax of the extinction and the onset of the re-diversification. Based on the study of new and rich conodont collections obtained from five sections (of which four are newly described here) in the Nanpanjiang Basin, South China, we have performed a thorough taxonomical revision and described one new genus and 21 new species. Additionally, we have critically reassessed the published conodont data from 16 other sections from South China, and we have used this new, standardized dataset to construct the most accurate, highly resolved, and laterally reproducible biozonation of the Smithian to early Spathian interval for South China. The resulting 11 Unitary Association Zones (UAZ) are intercalibrated with lithological and chemostratigraphical (δ13Ccarb) markers, as well as with ammonoid zones, thus providing a firm basis for an evolutionary meaningful and laterally consistent definition of the SSB. Our UAZ8, which is characterized by the occurrence of Icriospathodus ex gr. crassatus, Triassospathodus symmetricus and Novispathodus brevissimus, is marked by a new evolutionary radiation of both conodonts and ammonoids and is within a positive peak in the carbon isotope record. Consequently, we propose to place the SSB within the separation interval intercalated between UAZ7 and UAZ8 thus leaving some flexibility for future refinement and updating. ZooBank LSID: urn:lsid:zoobank.org:pub:12326FE6-79DD-43A8-9421-26C3883FBE2E
The growing digitization of fossil images has vastly improved and broadened the potential application of big data and machine learning, particularly computer vision, in paleontology. Recent studies show that machine learning is capable of approaching human abilities of classifying images, and with the increase in computational power and visual data, it stands to reason that it can match human ability but at much greater efficiency in the near future. Here we demonstrate this potential of using deep learning to identify skeletal grains at different levels of the Linnaean taxonomic hierarchy. Our approach was two-pronged. First, we built a database of skeletal grain images spanning a wide range of animal phyla and classes and used this database to train the model. We used a Python-based method to automate image recognition and extraction from published sources. Second, we developed a deep learning algorithm that can attach multiple labels to a single image. Conventionally, deep learning is used to predict a single class from an image; here, we adopted a Branch Convolutional Neural Network (B-CNN) technique to classify multiple taxonomic levels for a single skeletal grain image. Using this method, we achieved over 90% accuracy for both the coarse, phylum-level recognition and the fine, class-level recognition across diverse skeletal grains (6 phyla and 15 classes). Furthermore, we found that image augmentation improves the overall accuracy. This tool has potential applications in geology ranging from biostratigraphy to paleo-bathymetry, paleoecology, and microfacies analysis. Further improvement of the algorithm and expansion of the training dataset will continue to narrow the efficiency gap between human expertise and machine learning.
Andy S. Gale, Crispin T.S. Little, Joel E. Johnson
et al.
Valves of a thoracican cirripede belonging to a new species of the Neolepadidae, Ashinkailepas indica Gale sp. nov. are described from a Late Pleistocene cold seep (52.6 ka), cored in the Krishna-Godavari Basin, offshore from the eastern coast of India. This constitutes the first fossil record of the genus, and its first occurrence in the Indian Ocean. Other fossil records of the Neolepadidae (here elevated to full family status) are discussed, and it is concluded that only Stipilepas molerensis from the Eocene of Denmark, is correctly referred to the family. Cladistic analysis of the Neolepadidae supports a basal position for Ashinkailepas, as deduced independently from molecular studies, and the Lower Cretaceous brachylepadid genus Pedupycnolepas is identified as sister taxon to Neolepadidae. Neolepadids are not Mesozoic relics as claimed, preserved in association with the highly specialised environments of cold seeps and hydrothermal vents, but are rather an early Cenozoic offshoot from the clade which also gave rise to the sessile cirripedes.
Gonzalo D. Sottile, Yamila S. Giaché, María M. Bianchi
Resumen. La ecología de incendios es una actividad interdisciplinaria concerniente al estudio de los procesos naturales que involucran fuego en los ecosistemas y su interacción con los componentes bióticos y abióticos. Numerosos estudios orientados al conocimiento de la evolución de los ecosistemas naturales y humanos bajo la influencia recurrente del fuego atraviesan el trabajo interdisciplinario en el marco de la Ecología y de las Ciencias de la Tierra. El efecto de los incendios naturales y antrópicos en la evolución del paisaje, su impacto en las comunidades de bosque y la respuesta de los ecosistemas a los incendios son temas de debate y deben ser evaluados en diferentes escalas, tanto temporales como espaciales. En este trabajo se presentan algunos ejemplos que ponen en evidencia en qué medida la metodología aplicada al estudio de la producción, dispersión y depositación del carbón vegetal sedimentario o charcoal en cuencas lacustres y humedales contribuye a dar respuestas a estos interrogantes, se realiza una actualización bibliográfica y se describen algunos ejemplos de los estudios a escala de siglos a milenios, realizados hasta el momento en el sur de América del Sur.
Palabras clave. Paleoecología. Palinología. Métodos de reconstrucción de la historia de incendios. Ecología del fuego. Holoceno. Pleistoceno Tardío.
Abstract. FIRE REGIME RECONSTRUCTION IN PATAGONIAN TEMPERATE ECOSYSTEMS BASED ON CHARCOAL AND POLEN RECORDS DURING THE LATE QUATERNARY. METHODOLOGICAL TRENDS, RESULTS AND PERSPECTIVES. Fire ecology is an interdisciplinary activity concerning the study of natural processes that involve fire interactions with biotic and abiotic components of the ecosystems. Numerous studies focused on the knowledge of the evolution of natural and human ecosystems under the recurrent influence of fire need the interdisciplinary work between Ecology and Earth Sciences. The effect of natural and anthropogenic fires on the evolution of the landscape, its impact on forest communities and the response of ecosystems to fires are topics for debate and should be evaluated at both temporal and spatial scales. In this paper we present some examples that show the extent to which the methodology applied to the study of the production, dispersion and deposition of sedimentary charcoal in lake basins and wetlands contributes to give answers to these debates. We also present some updated references and describe examples of these paleoecological studies focused at centuries to millennia scales in southern South America.
Key words. Paleoecology. Palynology. Fire history reconstruction methods. Fire ecology. Holocene. Late Pleistocene.
Clypeasteroid echinoids are widespread and abundant within Miocene sedimentary sequences of the Mediterranean area within both siliciclastic and carbonate deposits. Herein, three clypeasteroid-dominated echinoid assemblages from the mixed siliciclastic-carbonate succession of the Mores Formation (lower Miocene) cropping out within the Porto Torres Basin (northern Sardinia) are described. These assemblages were compared to previously described clypeasteroid-bearing deposits from the Miocene of northern Sardinia with the purpose of investigating their palaeoecology and taphonomy along a shelf gradient. These goals are accomplished by various methods including (i) logging sedimentary facies, (ii) analysing the functional morphology of sea urchin skeletons, (iii) comparing the relative abundance of taxa and taphonomic features, and (iv) studying associated fauna, flora, and trace fossils. The clypeasteroid-bearing deposits differ greatly with respect to echinoid diversity, accompanying fauna and flora, sedimentological signatures, and taphonomic features. They also show variations in depositional environments and the mechanism of formation of the deposits. Three different shelf settings are distinguished: littoral, inner sublittoral, and outer sublittoral environments. Furthermore, an ecomorphological gradient along the shelf is recognized with respect to echinoid taxa and their morphologies. This gradient ranges from shallow water to a moderately deep shelf and is interpreted with respect to both abiotic and biotic factors as well as the taphonomy of the echinoid tests.
Krzysztof Hryniewicz, Kazutaka Amano, Robert G. Jenkins
et al.
We present a systematic study of thyasirid bivalves from Cretaceous to Oligocene seep carbonates worldwide. Eleven species of thyasirid bivalves are identified belonging to three genera: Conchocele, Maorithyas, and Thyasira. Two species are new: Maorithyas humptulipsensis sp. nov. from middle Eocene seep carbonates in the Humptulips Formation, Washington State, USA, and Conchocele kiritachiensis sp. nov. from the late Eocene seep deposit at Kiritachi, Hokkaido, Japan. Two new combinations are provided: Conchocele townsendi (White, 1890) from Maastrichtian strata of the James Ross Basin, Antarctica, and Maorithyas folgeri (Wagner and Schilling, 1923) from Oligocene rocks from California, USA. Three species are left in open nomenclature. We show that thyasirids have Mesozoic origins and appear at seeps before appearing in “normal” marine environments. These data are interpreted as a record of seep origination of thyasirids, and their subsequent dispersal to non-seep environments. We discuss the age of origination of thyasirids in the context of the origin of the modern deep sea fauna and conclude that thyasirids could have deep sea origins. This hypothesis is supported by the observed lack of influence of the Cretaceous and Paleogene Oceanic Anoxic Events on the main evolutionary lineages of the thyasirids, as seen in several other members of the deep sea fauna.
E. Bruner, José Manuel de la Cuétara, Michael P Masters
et al.
Anatomical systems are organized through a network of structural and functional relationships among their elements. This network of relationships is the result of evolution, it represents the actual target of selection, and it generates the set of rules orienting and constraining the morphogenetic processes. Understanding the relationship among cranial and cerebral components is necessary to investigate the factors that have influenced and characterized our neuroanatomy, and possible drawbacks associated with the evolution of large brains. The study of the spatial relationships between skull and brain in the human genus has direct relevance in cranial surgery. Geometrical modeling can provide functional perspectives in evolution and brain physiology, like in simulations to investigate metabolic heat production and dissipation in the endocranial form. Analysis of the evolutionary constraints between facial and neural blocks can provide new information on visual impairment. The study of brain form variation in fossil humans can supply a different perspective for interpreting the processes behind neurodegeneration and Alzheimer’s disease. Following these examples, it is apparent that paleontology and biomedicine can exchange relevant information and contribute at the same time to the development of robust evolutionary hypotheses on brain evolution, while offering more comprehensive biological perspectives with regard to the interpretation of pathological processes.
Hirotsugu Mori , Patrick S. Druckenmiller, Gregory M. Erickson
The Liscomb bonebed in the Price Creek Formation of northern Alaska has produced thousands of individual bones of a saurolophine hadrosaurid similar to Edmontosaurus; however, the specific identity of this taxon has been unclear, in part because the vast majority of the remains represent immature individuals. In this study, we address the taxonomic status of the Alaskan material through a comparative and quantitative morphological analysis of juvenile as well several near adult-sized specimens with particular reference to the two known species of Edmontosaurus, as well as a cladistic analysis using two different matrices for Hadrosauroidea. In the comparative morphological analysis, we introduce a quantitative method using bivariate plots to address ontogenetic variation. Our comparative anatomical analysis reveals that the Alaskan saurolophine possesses a unique suite of characters that distinguishes it from Edmontosaurus, including a premaxillary circumnarial ridge that projects posterolaterally without a premaxillary vestibular promontory, a shallow groove lateral to the posterodorsal premaxillary foramen, a relatively narrow jugal process of the postorbital lacking a postorbital pocket, a relatively tall maxilla, a relatively gracile jugal, a more strongly angled posterior margin of the anterior process of the jugal, wide lateral exposure of the quadratojugal, and a short symphyseal process of the dentary. The cladistic analyses consistently recover the Alaskan saurolophine as the sister taxon to Edmontosaurus annectens + Edmontosaurus regalis. This phylogenetic assessment is robust even when accounting for ontogenetically variable characters. Based on these results, we erect a new taxon, Ugrunaaluk kuukpikensis gen. et sp. nov. that contributes to growing evidence for a distinct, early Maastrichtian Arctic dinosaur community that existed at the northernmost extent of Laramidia during the Late Cretaceous.