Diverse Fossil Research Articles

THE ROLE OF SURFICIAL BIOTURBATION IN THE LATEST EDIACARAN: A QUANTITATIVE ANALYSIS OF TRACE FOSSIL INTENSITY IN THE TERMINAL EDIACARAN–LOWER CAMBRIAN OF CALIFORNIA

ABSTRACT Bioturbating activities have played a vital role in shaping the marine ecosystem throughout metazoan history, influencing the abundance and preservation potential of body fossil-producing taxa and driving major environmental and geochemical changes. The earliest trace making behaviors arose during the late Ediacaran Period (∼ 560–541 Ma), disrupting the substrate previously occupied by dominantly sessile organisms. Simple dwelling and grazing behaviors exploited the organic-rich matgrounds, expanding into the underutilized microbial mat ecosystem. In the western United States, trace assemblages from Ediacaran–Cambrian boundary-spanning deposits document a thriving trace-maker ecosystem. One boundary-spanning deposit in this region, the lower member of the Wood Canyon Formation, crops out along the California-Nevada boundary and contains both trace and body fossil assemblages. The Chicago Pass section of the lower Wood Canyon Formation contains a suite of dominantly simple Ediacaran traces, which become commonplace in the upper part of the stratigraphic section, documenting the onset of prevalent trace-making behaviors in this region. While traces have been previously described from this locality, the addition of the complex trace Lamonte trevallis and quantification of trace fossil density of simple Ediacaran traces provides a more comprehensive ichnological view of the Chicago Pass section. Although Chicago Pass does not yield abundant tubicolous body fossils, as are found elsewhere in the region, the low diversity ichnoassemblages document both burgeoning surficial trace making groups and mat-targeted mining in the latest Ediacaran. The behaviors present at Chicago Pass are similar to those of the Dengying Formation in South China, and highlight the need for petrographic-based trace fossil studies. Additionally, studies of Nama Group trace fossils of the same age from Namibia report higher diversity and complexity in trace-making activities than what has been observed at Chicago Pass, but with similar, low Ediacara biota body fossil diversity. If Ediacara biota diversity is anticorrelated with trace-making behaviors, Chicago Pass represents a low-complexity end-member of the same phenomenon observed in Namibia. The effect of surface sediment disruption on the sessile Ediacaran communities may have been decoupled from complexity of the traces, more so influenced by the presence of general trace-making behaviors in aggregate, including simple traces.

Human Genetic Research in Wallacea and Sahul: Recent Findings and Future Prospects.

Genomic sequence data from worldwide human populations have provided a range of novel insights into our shared ancestry and the historical migrations that have shaped our global genetic diversity. However, a comprehensive understanding of these fundamental questions has been impeded by the lack of inclusion of many Indigenous populations in genomic surveys, including those from the Wallacean archipelago (which comprises islands of present-day Indonesia located east and west of Wallace's and Lydekker's Lines, respectively) and the former continent of Sahul (which once combined New Guinea and Australia during lower sea levels in the Pleistocene). Notably, these regions have been important areas of human evolution throughout the Late Pleistocene, as documented by diverse fossil and archaeological records which attest to the regional presence of multiple hominin species prior to the arrival of anatomically modern human (AMH) migrants. In this review, we collate and discuss key findings from the past decade of population genetic and phylogeographic literature focussed on the hominin history in Wallacea and Sahul. Specifically, we examine the evidence for the timing and direction of the ancient AMH migratory movements and subsequent hominin mixing events, emphasising several novel but consistent results that have important implications for addressing these questions. Finally, we suggest potentially lucrative directions for future genetic research in this key region of human evolution.

Grimmipollis burmanica gen. et sp. nov.: New genus of the soapberry family (Sapindaceae) from the late Eocene of central Myanmar

As a crossroads for plant dispersal between Laurasia and Gondwana since at least the late Eocene, the Central Myanmar Basins have yielded rich and diverse fossil pollen. Here we report Grimmipollis burmanica, a new genus and species in the soapberry family (Sapindaceae) from the upper Eocene Yaw Formation in the Central Myanmar Basins. We also investigate its similarity of pollen sculpture with other selected genera using hierarchical cluster analysis, and its source paleoecology with pollen diagrams. Grimmipollis pollen grains are characterized by parasyncolporate apertures with an apocolpial field at each side, distinct margines along the colpi, arcuate, tuberculate and rope-shaped mesocolpial ridges, and prominent, verrucate or fossulate apocolpia. These features distinguish this genus from other syncolporate and parasyncolporate types in the extant Sapindaceae genera, and fossil pollen genera. As most syncolporate and parasyncolporate types occur in the tribe Cupanieae, G. burmanica is likely derived from an extinct Cupanieae and thus a rainforest tree species. The hierarchical cluster analysis confirms our establishment of Grimmipollis, and reveals it is morphologically close to Meyeripollis. The sedimentary environment from which these pollen grains were retrieved suggests that G. burmanica could be a member of seasonal swamp forests.

The rangeomorph fossil Charnia from the Ediacaran Shibantan biota in the Yangtze Gorges area, South China

Abstract The terminal Ediacaran Shibantan biota (~550–543 Ma) from the Dengying Formation in the Yangtze Gorges area of South China represents one of the rare examples of carbonate-hosted Ediacara-type macrofossil assemblages. In addition to the numerically dominant taxa—the non-biomineralizing tubular fossil Wutubus and discoidal fossils Aspidella and Hiemalora, the Shibantan biota also bears a moderate diversity of frondose fossils, including Pteridinium, Rangea, Arborea, and Charnia. In this paper, we report two species of the rangeomorph genus Charnia, including the type species Charnia masoni Ford, 1958 emend. and Charnia gracilis new species, from the Shibantan biota. Most of the Shibantan Charnia specimens preserve only the petalodium, with a few bearing the holdfast and stem. Despite overall architectural similarities to other Charnia species, the Shibantan specimens of Charnia gracilis n. sp. are distinct in their relatively straight, slender, and more acutely angled first-order branches. They also show evidence that may support a two-stage growth model and a epibenthic sessile lifestyle. Charnia fossils described herein represent one of the youngest occurrences of this genus and extend its paleogeographic and stratigraphic distributions. Our discovery also highlights the notable diversity of the Shibantan biota, which contains examples of a wide range of Ediacaran morphogroups. UUID: http://zoobank.org/837216cd-4a4a-4e13-89e2-ee354ba48a4c

New species from the early Eocene London Clay suggest an undetected early Eocene diversity of the Leptosomiformes, an avian clade that includes a living fossil from Madagascar

We report the first records of the leptosomiform taxon Plesiocathartes from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK). Two species could be distinguished, one of which is described as Plesiocathartes insolitipes, sp. nov. (the other is classified as Plesiocathartes sp.). We furthermore describe two small leptosomiform-like birds from Walton-on-the-Naze, Waltonavis paraleptosomus, gen. et sp. nov. and W. danielsi, gen. et sp. nov., which are represented by partial skeletons of multiple individuals. In plesiomorphic characters of the coracoid and furcula, the new taxon Waltonavis is distinguished from Plesiocathartes and the extant Leptosomus; the skull of Waltonavis furthermore exhibits basipterygoid processes, which are absent in Leptosomus. Another new species, Lutavis platypelvis, gen. et sp. nov., is based on a partial skeleton from Walton-on-the-Naze and closely resembles Plesiocathartes in the overall shape of the tarsometatarsus. However, L. platypelvis is clearly distinguished from leptosomiform birds in the morphology of the hypotarsus, the more massive coracoid, and other skeletal features. Although we consider close affinities to Plesiocathartes and, hence, the Leptosomiformes to be possible, we could not identify derived characters that enable an unambiguous phylogenetic placement of L. platypelvis. In any case, the new species document an unexpected diversity of Plesiocathartes-like fossil in the London Clay and may open a new perspective for a reconstruction of the ancestral morphology of the avian clade Afroaves, which includes the Leptosomiformes and other arboreal landbirds.

Biostratigraphic and palaeoenvironmental significance of a rich tetrapod fossil accumulation in the Lower to Middle Burgersdorp Formation of the Karoo Basin

Almost forty years of field investigations on the farm Lemoenfontein, near Aliwal North in the southern Free State Province of South Africa, have recovered a diverse amniote fauna from rocks of the Burgersdorp Formation that are assigned to the lower Middle Triassic Trirachodon-Kannemeyeria Subzone of the Cynognathus Assemblage Zone (AZ). In total, 140 skulls and articulated skeletons of seven tetrapod taxa have been collected, along with more recently collected details about their depositional environmental setting. Trace fossils including three different burrow casts, each with distinctive geometries, were also collected and documented. The amniote specimens include both juveniles and adults of the procolophonids Teratophon spinigenis and Thelephon contritus; the rhynchosaur Eohyosaurus wolvaardti; bauriid therocephalian Microgomphodon oligocynus; and the cynodonts Cricodon kannemeyeri and Trirachodon berryi. The diverse fauna is dominated by largely herbivorous tetrapods, mainly procolophonids, all with dentitions adapted to browse fibrous plant material. The only carnivore present is a small unidentified basal cynodont. Several of these tetrapods have previously been proposed as burrowers. The diversity and abundance of well-preserved fossils provide new insight into how palaeoenvironmental and behavioural factors contributed to the hyper-accumulation of tetrapod fossils at this site. Whilst the herbivorous dicynodont Kannemeyeria simocephalus and carnivorous erythrosuchid archosaur Erythrosuchus africanus are common components of the middle Cynognathus AZ Trirachodon-Kannemeyeria Subzone elsewhere in the basin, they are absent from the lower exposures at Lemoenfontein, which suggests that the fossil assemblage represents a transitional fauna from the Langbergia-Garjainia and Trirachodon-Kannemeyeria Subzones. Another interesting aspect of the site is that all the tetrapod remains are of individuals of small body size. This apparent Lilliput effect supports the view that the faunal recovery after the Permian-Triassic mass extinction in the Karoo Basin was only fully developed by Middle Triassic times.

A previously overlooked, highly diverse early Pleistocene elasmobranch assemblage from southern Taiwan.

The Niubu fossil locality in Chiayi County, southern Taiwan is best known for its rich early Pleistocene marine fossils that provide insights into the poorly understood past diversity in the area. The elasmobranch teeth at this locality have been collected for decades by the locals, but have not been formally described and have received little attention. Here, we describe three museum collections of elasmobranch teeth (n = 697) from the Liuchungchi Formation (1.90–1.35 Ma) sampled at the Niubu locality, with an aim of constructing a more comprehensive view of the past fish fauna in the subtropical West Pacific. The assemblage is composed of 20 taxa belonging to nine families and is dominated by Carcharhinus and Carcharodon. The occurrence of †Hemipristis serra is of particular importance because it is the first Pleistocene record in the area. We highlight high numbers of large Carcharodon carcharias teeth in our sample correlating to body lengths exceeding 4 m, along with the diverse fossil elasmobranchs, suggesting that a once rich and thriving marine ecosystem in an inshore to offshore shallow-water environment during the early Pleistocene in Taiwan.

Protection of the DNA from Selected Species of Five Kingdoms in Nature by Ba(II), Sr(II), and Ca(II) Silica-Carbonates: Implications about Biogenicity and Evolving from Prebiotic Chemistry to Biological Chemistry.

The origin of life on Earth is associated with the Precambrian era, in which the existence of a large diversity of microbial fossils has been demonstrated. Notwithstanding, despite existing evidence of the emergence of life many unsolved questions remain. The first question could be as follows: Which was the inorganic structure that allowed isolation and conservation of the first biomolecules in the existing reduced conditions of the primigenial era? Minerals have been postulated as the ones in charge of protecting theses biomolecules against the external environment. There are calcium, barium, or strontium silica–carbonates, called biomorphs, which we propose as being one of the first inorganic structures in which biomolecules were protected from the external medium. Biomorphs are structures with different biological morphologies that are not formed by cells, but by nanocrystals; some of their morphologies resemble the microfossils found in Precambrian cherts. Even though biomorphs are unknown structures in the geological registry, their similarity with some biological forms, including some Apex fossils, could suggest them as the first “inorganic scaffold” where the first biomolecules became concentrated, conserved, aligned, and duplicated to give rise to the pioneering cell. However, it has not been documented whether biomorphs could have been the primary structures that conserved biomolecules in the Precambrian era. To attain a better understanding on whether biomorphs could have been the inorganic scaffold that existed in the primigenial Earth, the aim of this contribution is to synthesize calcium, barium, and strontium biomorphs in the presence of genomic DNA from organisms of the five kingdoms in conditions emulating the atmosphere of the Precambrian era and that CO2 concentration in conditions emulating current atmospheric conditions. Our results showed, for the first time, the formation of the kerogen signal, which is a marker of biogenicity in fossils, in the biomorphs grown in the presence of DNA. We also found the DNA to be internalized into the structure of biomorphs.

Биогенные структуры терригенных отложений пограничного пермо-триасового интервала Южного Верхоянья, Республика Саха (Якутия)

The article describes biogenic structures (trace fossils and bioturbation) of clastic rocks within the Permian-Triassic boundary interval in the Tiryakh-Kobyumeh section (Southern Verkhoyanye). The section is built by interbedding marine sandstones and siltstones, and is associated with the Late Permian mass extinction event. Most of the strata contain a variety of biogenic structures. Different taxonomic compositions of trace fossils and high bioturbation of Permian rocks indicate dense habitation of the basin bottom. In the Lower Triassic deposits, diversity of trace fossils sharply decreases as well as the degree of bioturbation. In the lower part of the Nekuchan suite's Triassic deposits, an interval of horizontally stratified rocks without bioturbation interbedded with rocks bioturbated by stratum has been identified. The interval is overlaid with highly bioturbated deposits, which indicates a rapid recovery of biodiversity after the Permian mass extinction.

Geodiversity in Khorat Geopark, Thailand: Approaches to geoconservation and sustainable development

This work aims to investigate the geodiversity of the Khorat Geopark area, Northeastern Thailand, and assess the geological sites that are connected to biological and cultural heritage, as well as community activities that enhance geoconservation and sustainable development. The geological diversity of Khorat Geopark dates back to the late Jurassic period and continues to the present day, resulting from the deposition of terrestrial sedimentary rocks from the Khorat Group. The Khorat rock group has been uplifted and eroded to form the Khorat Plateau with a unique landscape and important geological features of the cuesta landform on the western part of the Khorat Geopark. On the four corners of Nakhon Ratchasima City, there are numerous fossils of outstanding Early Cretaceous dinosaurs and other reptiles and Cenozoic fossils of both flora and fauna, mainly mammalian remains and, in particular, ancient elephants. Geological sites in the Khorat Geopark area were weighted and scored based on their scientific value (SV), potential value for education (EV), potential value for tourism (TV), and degradation risk variables (DV). According to the assessment, the Khorat Geopark's 24 geosites are of moderate to high value, with 7 sites having 301–400 scores and 5 sites having a high level of international value. Most of them are related to fossils and cuestas. Thus, the fossil diversity of the Khorat Geopark is of international scientific significance. Khorat Geopark is managed under the conservation, education, and sustainable development initiatives using a bottom-up method with multiple networks, both local communities and local governments, especially through the Home-Temple-School (HTS) model.

Microbiostratigraphy, microfacies analysis and lateral basin evolution of Lower Cretaceous deposits in the south of Kerman region, SE Iran

Detailed microbiostratigraphy and basin evolution of the Lower Cretaceous deposits in the Rayen area, south of Kerman Region, SE Iran are investigated for the first time in two sections. The section no. 1 is 324.6m in thickness and comprises five lithostratigraphic units. The section no. 2 is 218 m in thickness and includes three lithostratigraphic units. The identified fauna and flora include 41 benthic foraminifera and 11 calcareous algae species. The identified assemblage indicates that the marine strata in both sections were deposited during the Barremian to Albian. The microfacies analyses carried out on 22 carbonate and 2 clastic microfacies indicate that the deposits in the section no. 1 were deposited on a homoclinal carbonate ramp, whereas in the section no. 2 they were deposited on a rimmed carbonate shelf. Generally, the Cretaceous deposit in the two studied sections represent different sedimentary models and fossil content indicating different basin evolution histories. The paleogeographic setting of the studied area on the south eastern margin of the Central-East Iranian Microcontinent and the active tectonic history during the Mesozoic suggest that the syndepositional tectonism influenced the basement’s morphology and resulted in changes in the fossil diversity and sedimentary nature of adjacent sedimentary basins.

The skeletal taphonomy of anurans from the Eocene Geiseltal Konservat‐Lagerstätte, Germany: insights into the controls on fossil anuran preservation

AbstractThe Geiseltal biota is an Eocene lacustrine Konservat‐Lagerstätte in central Germany. Despite its rich fauna and flora (over 50 000 fossil vertebrates, insects and other invertebrates, plants and trace fossils) the taphonomy of the biota, and of the anurans in particular, is poorly understood. We analysed the skeletal taphonomy of 168 anurans, scoring each specimen for orientation, completeness and articulation. Most are partial skeletons, truncated during preparation. This process introduces measurable artefacts into the taphonomic data, which requires further study. We identified recurring taphonomic states, including disarticulation or loss of abdominal bones, loss of one or more limbs, extensive disarticulation, and extensive loss of elements across the body. Relatively rare states include: loss of distal limb elements only, scattered bones, and isolated, articulated limbs. These data inform a new taphonomic model for the Geiseltal anurans. Comparative analysis of patterns in completeness and articulation in these specimens and anurans from other Cenozoic Lagerstätten reveals repeated patterns in preservation in lacustrine‐hosted settings, such as proximal to distal trends in completeness, preferential loss of small peripheral bones, disarticulation of abdominal bones, and reorientation of major body regions. Taphonomic controls in lacustrine systems are surface water temperature, lake depth, vegetation, exposure to bottom currents, transport mechanisms, scavenging, decay regime, bone size and location in the skeleton; all ultimately controlled by palaeoclimate, lake physiography and hydrology, and anuran anatomy. A universal approach to quantitative analysis of skeletal taphonomy metrics will enable comparative testing of the relationship between preservation and palaeoenvironment for diverse fossil vertebrates.

Ichnofossils Characteristics in Pelagic Siliciclastic Carbonate Turbidites of Weda Formation, Halmahera Island

The Weda Formation in Lili River, Dorosagu, East Halmahera consists of siliciclastic and pelagic carbonates deposited in a submarine fan environment. Research on the Weda Formation in the northern part of Halmahera Island is relatively minimal because most of the research about this formation has been carried out in the southern part of Halmahera Island. The lack of road access and its remote location have resulted in the lack of intensive research on this formation. This study aims to determine the relationship between the intensity and diversity of trace fossils in the submarine fan facies association of the Weda Formation. Sedimentological studies include sedimentary texture, sedimentary structure, turbidite material type, and layer thickness. While the study of trace fossils includes the identification of trace fossil types, classification of behavior, intensity, and diversity in sedimentary layers, and the factors that influence them during deposition. There are eight types of ichnofossil observed in the Lili River, Ophiomorpha, Thalassinoides, Rhizocorallium, Palaeophycus, Zoophycos, Chondrites, Lorenzinia, and Spirorhaphe, which are found in three facies associations (AF): submarine fan channel facies association (AF1), submarine fan lobe facies association (AF2), and submarine fan distal facies association (FA3). The submarine fan channel facies is characterized by the presence of Ophiomorpha and Thalassinoides which present in low intensity and low diversity due to unstable environmental conditions-high stress due to intensive turbidite currents. The submarine fan lobe facies shows a higher density and diversity where ichnofossil is classified into two based on the substrate in the flysch deposits. Rhizocorallium, Thalassinoides, and Palaeophycus ichnofossil were formed in the sand substrate, while Zoophycos and Chondrites ichnofossil were formed in the shale substrate. Palaeophycus, Zoophycos, Chondrites, Lorenzinia, and Spirorhaphe ichnofossil were found in the submarine fan distal facies associated with high intensity indicating low energy levels and low sedimentation rates.

Lithostratigraphy, chronostratigraphy, and sedimentary environments of the middle Miocene Quebrada Honda Basin in southern Bolivia and implications for Andean climate and uplift

The late middle Miocene Quebrada Honda Basin of southern Bolivia has long been studied for its diverse fossils of terrestrial vertebrates and, more recently, for its record of paleoelevation and paleoclimate in the Eastern Cordillera of the Andes Mountains. This paleobiological and paleoenvironmental archive is constrained by high resolution radioisotopic ages linked to paleomagnetic reversal stratigraphy in multiple areas within the basin. Nevertheless, studies of the basin's stratigraphy have been limited and questions remain about how the sedimentary deposits and fossil horizons in different parts of the basin relate to each other. We confirm the identification of three lithostratigraphic units, show that the units extend across the basin, and examine the distribution of sedimentary and pedogenic facies and volcanic tuffs within them. We identify different styles and stages of pedogenic development that correspond to mappable differences in outcrop character. Volcanic tuffs and sedimentary and pedogenic facies exhibit high lateral continuity consistent with accumulation on a low relief basin floor. In contrast, sedimentary and pedogenic features change vertically over multiple scales reflecting secular variations in aridity and stability over seasonal to multimillennial scales. Erosional truncation of lithostratigraphic units and a ~ 700,000-year gap in the ages of superimposed strata delineate an erosional unconformity with >50 m of relief that was cut ~12 million years ago. Breach of the basin margin along a boundary between local structural blocks may account for the development of localized incision during a period when landscapes of the Eastern Cordillera were stable with little deformation or erosion. Regional landscape stability at that time has been attributed to low elevation or a position behind an orographic precipitation barrier. The sedimentary and pedogenic facies, faunal communities, and intraformational unconformity of the Quebrada Honda Basin favor a low elevation setting, which has implications for the timing and mechanisms of uplift of the Bolivian Andes.

New record of Jurassic Xenoxylon wood from Gansu, northwestern China, and its palaeoclimatic implications

ABSTRACT Fossil wood is a significant proxy for terrestrial palaeoclimate and palaeogeography. Abundant and diversified Mesozoic fossil wood has been documented in China. However, there are limited reports of Jurassic fossil wood records from northwest China. Herein, several calcified wood fossils are described in anatomical detail, from the Middle Jurassic (Bajocian to Callovian) Xinhe Formation in Gansu Province. They were identified as two species of the fossil wood genus Xenoxylon Gothan of Coniferales, namely X. latiporosum (Cramer) Gothan and X. peidense Zheng et Zhang. The newly collected material represents the first record of Jurassic petrified wood from Gansu Province. Based on the palaeoclimatic implication of Xenoxylon, we propose that the Baojishan Basin may have experienced a distinct short-term cooling during the Middle Jurassic. We analysed the fossil diversity and spatial-temporal distribution of Xenoxylon species in China. A total of 15 Xenoxylon species have been documented in China. These occurred from the Late Triassic to Late Cretaceous, but flourished from the Jurassic to Cretaceous intervals. Geographically, they are distributed across 13 provinces, mainly in northeast China. Significantly, this record expands the distribution of this important climate indicator taxon.

Temporal constraints on the terrestrial biota from the Yingzuilazi Formation (Baishan Basin), northeast China

The biota from the Yingzuilazi Formation in the Baishan Basin yields a diverse fossil assemblage (including a new described ostracod species Cypridea horni sp. nov. Wang), which provides a valuable opportunity to investigate the evolution of major terrestrial plants and animals. However, the age of this biota is still controversial. To address this, we report a new SIMS zircon U–Pb age of 128.5 ± 1.0 Ma for the uppermost part of the Yingzuilazi Formation. This age, combined with our new ostracod biostratigraphic age from the Yingzuilazi Formation, indicate that the age of biota from the Yingzuilazi Formation is mainly Barremian (∼129 Ma to ∼127 Ma). It seems that the biota from the Yingzuilazi Formation temporal coincides with Jehol Biota sensu stricto stage I, but it is closely related to Jehol Biota sensu stricto stage II in terms of comprehensive biostratigraphic and paleontoloical materials. Therefore, this biota shows the significances not only in understanding the spatiotemporal evolution of the Early Cretaceous terrestrial biotas in East Asia, but also in exploring the possible relationship between the terrestrial life evolution and the destruction processes of the North China Craton.

Earliest western Atlantic staghorn corals (Acropora) from the lower Oligocene Suwannee Limestone of Florida, USA, and their significance for modern coral distribution

AbstractThe Suwannee Limestone of Florida and Georgia, USA, is a carbonate paleoenvironment with a rich diversity of marine fossils. These record the presence of coral- and seagrass-bearing communities in the western Atlantic from the Eocene/Oligocene boundary to the mid Oligocene (33.9–28.1 Ma). From the Suwannee Limestone, we describe two new species of the cosmopolitan, diverse, and abundant coral genus Acropora (“staghorn corals”), Acropora suwanneensis new species and Acropora upchurchi new species, which predate all other described Acropora species from the Americas and Caribbean by at least 10 million years. Diminutive skeletal structure in both species is indicative of their living in protected calm-water habitats. At their time of occurrence, an Atlantic–Pacific connection was open through Central America. Both species belong to morphological lineages also present in the fossil record of the eastern Atlantic (Europe, or the western Tethys). These lineages no longer occur in the Atlantic Ocean, but they are extant in the Indo-Pacific region, with the closest modern relative of each new species occurring in the Pacific Ocean to central Indo-Pacific. Some species in the two morphological lineages have existed for up to 20+ million years. The new species may have played a part in perpetuating a cosmopolitan Tethyan fauna and expanding Acropora habitats in the western Atlantic, by which they likely also contributed to the renowned species and habitat diversity of Acropora in the modern Indo-Pacific.UUID https://zoobank.org/40118623-8b82-4352-a065-b58da74a5c41

A fresh look at the Hyolithid Doliutheca from the Early Cambrian (Stage 4) Shipai Formation of the Three Gorges Area, Hubei, South China.

Simple SummaryDoliutheca orientalis is revised from the Shipai Formation (early Cambrian Stage 4) of the Three Gorges area, South China. Specimens are preserved as casts in silty mudstone and as small shelly fossils in calcareous pelites. SEM and Micro-CT analyses show that Doliutheca possessed hyolithid-like skeletons (especially regarding the operculum) but significantly lack helens. This combination of features sees the genus placed within the Family Paramicrocornidae, a group of hyoliths closely related to hyolithids. Newly compressed specimens of Doliutheca from silty mudstone show some soft-part preservation with the gut clearly visible. Additionally, the highly variable apex morphology of Doliutheca is explained as a consequence of differences in preservation due to secondary deposits formed inside the shell. This finding highlights the challenge of preservational artefacts in calculating the disparity and diversity of early Cambrian skeletal fossils, and the resulting potential effects on taxonomic assessments on the diversity of skeletal taxa in the Cambrian.New hyolith specimens from the early Cambrian (Stage 4) of the Three Gorges area, western Hubei Province are described and assigned to the species Doliutheca orientalis. Doliutheca are preserved in two taphonomic modes: casts in silty mudstone revealing gross morphology and some soft parts, and internal molds in calcareous pelites, which exhibit new morphological details of the conch and operculum. SEM and Micro-CT analyses show that Doliutheca preserve well-developed platy clavicles and cardinal processes on the interior of the operculum composed of rod-shaped tubular elements. This observation and the distinct cardinal and conical shields of the operculum indicate that Doliutheca could be placed within the Family Paramicrocornidae, most recently established as a group of hyoliths closely related to hyolithids.

Fast-growing species shape the evolution of reef corals

Ecological interactions are ubiquitous on tropical coral reefs, where sessile organisms coexist in limited space. Within these high-diversity systems, reef-building scleractinian corals form an intricate interaction network. The role of biotic interactions among reef corals is well established on ecological timescales. However, its potential effect on macroevolutionary patterns remains unclear. By analysing the rich fossil record of Scleractinia, we show that reef coral biodiversity experienced marked evolutionary rate shifts in the last 3 million years, possibly driven by biotic interactions. Our models suggest that there was an overwhelming effect of staghorn corals (family Acroporidae) on the fossil diversity trajectories of other coral groups. Staghorn corals showed an unparalleled spike in diversification during the Pleistocene. But surprisingly, their expansion was linked with increases in both extinction and speciation rates in other coral families, driving a nine-fold increase in lineage turnover. These results reveal a double-edged effect of diversity dependency on reef evolution. Given their fast growth, staghorn corals may have increased extinction rates via competitive interactions, while promoting speciation through their role as ecosystem engineers. This suggests that recent widespread human-mediated reductions in staghorn coral cover, may be disrupting the key macroevolutionary processes that established modern coral reef ecosystems.

Lacertoid tracks from the Botucatu Formation (Lower Cretaceous) with different locomotor behaviors: A new trackmaker with novel paleoecological implications

The Botucatu Formation (Paraná Basin) is an eolian deposit that represents an extensive paleoerg that existed in the south-central Gondwana during the Early Cretaceous. The fossil record of the unit is almost exclusively constituted of ichnofossils, including numerous tracks and burrows of vertebrates and invertebrates. The greatest trace fossil diversity of the Botucatu Formation is reported at the Ouro ichnosite, located in the Araraquara municipality region, São Paulo State, Brazil. This site comprises a faunal-rich setting of greater humidity in the ancient desert. In this work, a new footprint morphotype is reported for the Ouro ichnosite. Five trackways including tracks with an elongated anteroposterior axis associated with tail drag marks are described. The morphology of the autopodia and geometry of the trackways indicate an affinity with a lizard-like trackmaker. Furthermore, at least three different modes of locomotion were recognized: a typical walking gait, a pause-walking gait, and sideways drifting. The current report suggests Lepidosauria may have inhabited the ancient Botucatu desert, a group never reported before in this geological context. This finding expands the knowledge about the Botucatu Formation paleofauna and adds more complexity to its ecological network. Squamata and Sphenodontia are plausible candidates to have produced the described fossil tracks.