New Lower (?Middle) Devonian ammonoids are described from the Norton Gully Sandstone and Montys Hut Formation in the Melbourne Zone of central Victoria. They confirm a lower Emsian age for the first, and suggest an upper Emsian to possibly basal Eifelian age for the second. Taxonomic relationships among the lower Emsian Anetoceratidae and especially of its gyroconic genera are discussed. Ivoites is compared with the partially neglected Chinese genus Luofuceras, leading to re-assignments of species to both genera. Based on a different number of whorls, Ivoites is subdivided into the subgenera Ivoites (Ivoites) and I. (Kaubites) n. subgen. (with I. schindewolfi as the type species). The gyroconic Norton Gully Sandstone goniatite is named as Ivoites (Ivoites) talenti n. sp. and indicates a lower Emsian horizon (LD III-B to LD III-E ammonoid zones). The abundant, distinctively ornamented form from the Montys Hut Formation is described as ?Chlupacites eildonensis n. sp. (Agoniatitidae), with a second, much smoother, indeterminate species represented by a single fragment; these are probably upper Emsian in age, although the lower Eifelian cannot be fully ruled out. All Lower Devonian ammonoids of Victoria belong to endemic species, but at the generic level there are ties along the pantropical Prototethys belt, connecting Australia and Central Europe (Rhenish Massif).
This study presents a detailed taphonomic analysis of the depositional context in Toca da Boa Vista cave, northeastern Brazil, integrating biostratinomic features, ichnological traces, and antemortem bone modifications aiming to reconstruct its depositional history. The assemblage is characterized by a low-energy environment and in situ preservation, as indicated by the abundance of complete specimens (60.1%), and skeletal elements spanning all transportability groups, as well as low frequencies of abrasion (3.7%), corrosion (1.8%), and moisture-induced cracking (10.3%). The taphonomic setting suggests quick burial with limited environmental alteration, although delayed burial or episodic exhumation of low-density bones locally promoted surface modification. Perforations assigned to Karethraichnus on bones of Nothrotherium maquinense provide evidence of necrophagous activity of insect activity within the cave environment, and indicate that carcasses remained exposed prior to burial, contributing to the reconstruction of the depositional environment. Antemortem alterations, including healed traumatic injuries and abnormal bone growth, indicate that some individuals experienced physiological stress before death, which may have reduced mobility and increased their dependence on the cave for protection. Together, these results support the interpretation of Toca da Boa Vista as a natural refuge and water source for the local fauna. The study also expands the taphonomic framework for Brazilian cave deposits and provides new insights into the preservation of Quaternary vertebrate assemblages in tropical karst environments.
The large collection of Pachycrocuta brevirostris cranial material from the Late Villafranchian deposits of Taurida cave was studied. Morphological and morphometrical dental characters of Pachycrocuta from this site were compared with other Eurasian P. brevirostris to define evolutionary trends of this key carnivore species. The study showed that the degree of hypercarnivorous adaptation increased during the existence of the taxon, manifested by relative reduction of P2 and p2, reduction of p3 mesial basal cusp, and reduction in the number of m1 talonid cusps. The trend of increasing overall dentition size and robustness of p2 and p3 indicated deepening adaptation to bone-cracking. P. brevirostris from Taurida generally exhibit dental features similar to other Late Villafranchian P. brevirostris, but differ from them in having large premolars, with some p2 specimens exceeding those of any other P. brevirostris in size.
Anuran remains from the Nemegt Formation (Maastrichtian) at the Gurilin Tsav locality in Mongolia are described and assigned to Gobiates sp. and discoglossid-like Anura indet. The material attributed to Gobiates (frontoparietal, maxilla and ilium) represents the first reliable gobiatid record from the Maastrichtian of Asia. The frontoparietal of Gobiates sp. exhibits a combination of pit-and-ridge and tubercular ornamentation, an unusual for gobiatids that may represent a derived condition within the Gobiatidae clade. A large Anura indet. (known from a fragmentary maxilla) is comparable in size to other Asian Late Cretaceous discoglossid-like anurans. The co-occurrence of gobiatid and discoglossid-like anurans — a faunal association typical of the Cenomanian–Campanian of Middle Asia and Kazakhstan — is documented here for the first time from the Upper Cretaceous of Mongolia. This faunal association of gobiatids and discoglossids appears to have been temporally stable across Asia, persisting over an interval encompassing nearly the entirety of the Late Cretaceous (approximately 30 million years). The Late Cretaceous anuran faunas of Asia are characterized by temporary stable faunal composition, low diversity at the high taxonomic level, and the endemism (the presence of gobiatids).
High-speed dinosaur trackways that preserve both gait kinematics and footprint anatomy are rare because the substrate conditions that permit rapid locomotion are commonly incompatible with those that retain fine impressions. Here we report a tridactyl bipedal ornithopod trackway from the Hasandong Formation (Aptian–Albian), Juji Island, Republic of Korea, and show that its exceptional preservation records a narrow ‘Goldilocks’ substrate window coupled with event-style burial. The trackway comprises three consecutive natural casts preserved on the upper surface of a laterally continuous brownish grey mudstone (facies Fhbg) interpreted as an oxbow margin mudflat. 3D photogrammetry and ichnological measurements yield a relative stride length of SL/h = 2.84, consistent with a running gait, and an estimated speed of ∼4.95 m/s. Sedimentological criteria constrain both track formation and stabilization: (i) the track surface lacks desiccation cracks and pedogenic calcrete nodules, indicating persistently wet conditions, yet preserves sharp tridactyl outlines, implying a cohesive-but-plastic substrate; and (ii) the sharp, low-relief contact with the overlying channel sandstone, together with the absence of basal rip-up mud clasts, indicates non-erosive sand blanketing/infill onto (or across) standing water rather than scour. Sand delivered during a channel reactivation/annexation phase rapidly infilled the impressions, sealed the surface, and promoted long-term preservation as casts. Comparison with representative global tracksites highlights how trackway-level kinematic signals may survive even where footprint-level fidelity is often erased by substrate rheology. The Juji Island trackway provides an event-stratigraphic record linking short-duration fluvial instability with the preservation of running dinosaur locomotion.
The Cambrian–Ordovician strata are well preserved in the Quruqtagh area of the Tarim Basin. While extensive work on the biostratigraphy and sedimentology of this region has been done, comprehensive studies integrating biostratigraphic and carbon isotope stratigraphic data remain relatively scarce. In this study, a detailed, integrated latest Cambrian stratigraphic sequence was established for the Wuligezitage area, and the first systematic carbon isotope was analyzed herein.The new findings clearly record the TOCE (Top of Cambrian Excursion) event in the northern part of the Quruqtagh area, facilitating extensive global carbon isotope stratigraphic correlations. The TOCE may have been triggered by a marine oxygenation pulse, which released light carbon via the oxidation of marine dissolved organic carbon and/or reduced organic carbon burial resulting from the contraction of oxygen-deficient intermediate water masses.This study establishes a direct and potentially causal relationship between TOCE, marine oxygenation, and sea-level fall, providing critical insights into the co-evolution of carbon cycle perturbations and environmental changes during late Cambrian.
The Pliocene–Pleistocene marine sedimentary sequences of the Saurashtra Basin, Gujarat, India, host a rich archive of molluscan fauna, typical of the Western Indo-Pacific biogeographic realm. Despite this, the region has been relatively underexplored paleontologically, especially when compared to other contemporaneous areas within the same/other biogeographic realm(s). This absence of comprehensive systematic or diversity studies has created a major gap in understanding the Pliocene–Pleistocene marine diversity trend from the Saurashtra Basin, as well as hindering further ecological, evolutionary, and biogeographic analyses thereof. In this study, we present the first comprehensive systemic and diversity-based assessment of the Pliocene–Pleistocene molluscan assemblages of this basin, incorporating several previously undocumented faunas and refining earlier records to higher taxonomic precision. Diversity analyses, incorporating Shannon H, based on individual and coverage-based rarefaction analyses, reveal a long-term incremental trend from the Pliocene to the Pleistocene, peaking at the youngest Pleistocene unit, where a statistically significant change in diversity is observed. This study thus provides the most robust baseline of systematics and diversity assessment for the Pliocene–Pleistocene molluscan assemblages of the Saurashtra Basin, Gujarat, India.
New anthracotheriid material collected from the coal deposit in Na Duong in northwestern Vietnam can be attributed to the three microbunodontine and bothriodontine taxa already known from there, with emendation of their diagnoses. The dental morphology of these fossils also confirms the early late to middle late Eocene age proposed for the Vietnamese mammalian community. However, no new fossil material could be referred to the rare species of Elomeryx that was previously described from Na Duong. The morphological resemblances between the Bothriogenys species from Na Duong and from the Fayum in North Africa reinforce the hypothesis of a Southeast Asian origination of the late Eocene North African anthracothere fauna. However, the similar dental affinities of the Na Duong microbunodontine and those from China suggest that geographical barriers were probably an obstacle to some faunal exchanges between northwestern Vietnam and more western regions like Thailand (Krabi) and Myanmar (Pondaung) during part of the late Eocene.
Trace fossil assemblages in the Ordovician–lower Silurian Vuddudalen and Ekne groups, Central Norwegian Caledonides, evolved in a complex submarine topography, with various depositional environments in a back-arc basin on the Laurentian margin of the Iapetus Ocean. Trace fossils in basin plain turbidite deposits in Vuddudalen-Åsen are attributed to the Nereites ichnofacies, while assemblages in meta-sedimentary shelf and slope fan strata in the Hegra, Lånke and Stjørdal areas may be assigned to this ichnofacies. These deposits are overlain by deposits with trace fossil assemblages of the Cruziana ichnofacies found in inner shelf settings. In the uppermost part of the Vuddudalen Group in Stjørdal, the low ichno-diversity is typical of the shallow-marine Skolithos ichnofacies. Body fossils are rare, but trace fossils indicate benthic communities with arthropods, bivalves, gastropods, polychaetes, and possibly sea anemones. The changes in sedimentary facies and ichnofacies from deep marine shales and fan-fringe basin-floor deposits in the lower to middle Vuddudalen Group to shelf and nearshore, sand-rich deposits in the upper part and in the overlying Ekne Group, were related to tectonic activities and infilling of the volcanic arc basin prior to the closure of the Iapetus Ocean, and to the overall global lowering of sea-level coinciding with the Late Ordovician (Hirnantian) glaciation.
The Eocene record of elasmobranchs in the eastern Neotethys (Indo-Pacific area) remains notably sparse, especially when compared to that of its western counterpart, which borders North America, Europe, and North Africa. This study provides the second comprehensive account of Middle–Late Eocene elasmobranch assemblages from Myanmar and documents the presence of seven Carcharhiniforms and Batoids, including a newly identified fossil species of carcharhinid. The faunal composition, dominated by euryhaline or freshwater-tolerant taxa such as Dasyatidae, Pristidae, and Odontorhytis pappenheimi, strongly indicates a depositional environment influenced by brackish water or substantial freshwater input, consistent with sedimentological evidence and observations from contemporary sites in North Africa. The occurrence of these taxa in Myanmar represents the easternmost record of several Late Eocene elasmobranchs, emphasizing ancient dispersal routes along the tropical Atlantic and Neotethys coasts. This modest assemblage highlights the potential for greater elasmobranch diversity in the dynamic Neotethys during the Palaeogene than is currently recognized and may signal early shifts of biodiversity hotspots towards the Indo-Pacific.
This study presents a high-resolution multiproxy reconstruction of early Holocene paleoenvironmental variability (∼10.8–9.8 ka) in the southern Gulf of California based on the DIPAL IV sediment core. Dinoflagellate cyst assemblages, continental palynomorphs, total organic carbon (TOC), biogenic opal, and X-ray fluorescence (XRF)-derived elemental ratios (Fe/Al, Ti/Al) were analysed to assess changes in surface-water conditions, productivity, and terrigenous input. The record reveals a progression from older to younger sediments characterized by a marked decrease in terrigenous influence — declining Fe/Al and Ti/Al ratios and continental palynomorphs — accompanied by only a weak increase in TOC and broadly stable biogenic opal. Heterotrophic and autotrophic cyst concentrations covary strongly and the autotroph proportion shows no temporal trend, indicating that bulk trophic structure remained stable; the difference among units is instead a species-level compositional turnover among gonyaulacoid taxa, notably Spiniferites. Stratigraphically constrained clustering, ANOSIM, PERMANOVA and SIMPER identify three statistically distinct paleoenvironmental units, the basal one being the most distinct. Integrating geochemical and palynological proxies shows that the pronounced decline in terrigenous input was decoupled from the dinoflagellate compositional turnover, underscoring that bulk geochemistry and assemblage composition capture complementary aspects of early Holocene environmental change in this semi-enclosed marginal basin.
Permian ammonoids in Xizang (Tibet) are rare and poorly documented. In this study, we describe two ammonoid species, i.e., Stacheoceras trimurti Diener, 1897 and a new species Stacheoceras resaensis n. sp., from the Xiukang limestone block in the Yarlung-Zangbo Suture Zone. This finding increases the known ammonoid diversity of the Xiukang limestone and its surrounding blocks from eight to ten species. The occurrence of S. trimurti indicates a Wuchiapingian age. By summarizing ammonoid, brachiopod, fusulinid and conodont data, we reassess the age range of the limestone blocks in Lhaze County, which spans from the Wordian to the Wuchiapingian, and possibly extends into the Induan. Finally, we summarise the taxonomy of Stacheoceras, recording at least 32 valid species, and discuss their temporal and spatial distributions. Stacheoceras first appeared in the Kungurian and persisted until the Changhsingian, with a palaeogeographic distribution largely confined to low- and mid-latitude regions.
Situated within the southwestern segment of Chongqing, the Zhengyang Basin formed one of the intermountain basins within the Yanshanian orogenic belt that developed during the Late Cretaceous. The Zhengyang Basin preserves a > 100 m-thick Upper Cretaceous terrestrial successions, named the Zhengyang Formation characterized by debris-flow deposits and fluvial-lacustrine units. Recently, abundant dinosaur fossils have been collected from this formation, including hadrosaurs, titanosaurs, and theropods, providing substantial evidence of an exceptional middle Late Cretaceous dinosaur fauna in Southwest China. We herein report detailed stratigraphic architecture, dinosaur fossil assemblage, sedimentary and palaeoenvironmental features of the Zhengyang Formation in the Zhengyang Basin. The evidence suggests that the dinosaurs lived in a restricted intermountain basin, of which the palaeoclimate was significantly influenced by a transition from overall humid to arid condition. Our data lead to new evaluation of early Late Cretaceous dinosaur evolution, and provide new clues for investigation on the contemporary terrestrial palaeoenvironmental and palaeoclimatic features in the mid-low latitude area of East Asia. The stratigraphic features of the Zhengyang Formation also provide new insights into showing lateral correlation of the Late Cretaceous terrestrial successions in East Asia.
The Zhujiang Formation in the Baiyun Sag of the Pearl River Mouth Basin developed a high-quality Globigerinid-rich limestone reservoir, with core porosity up to 38%, mainly derived from foraminiferal shells. Therefore, understanding the enrichment mechanism and distribution of Globigerinids is key to predicting high-quality reservoirs. In this study, the foraminiferal composition and paleo-environment of Well L4-1 in the Baiyun Sag are systematically analyzed. Nine genera and 11 species of planktonic foraminifers, and 45 genera and 53 species of benthic foraminifers were quantitatively identified, with an average abundance of 9500 individuals per gram of sediment. The occurrence of Planktonic foraminifers indicates a geological age of the late early Oligocene for the studied section. Based on the shell Mg/Ca ratios of Paragloborotalia nana, the subsurface temperature was estimated to be 17.4–17.1°C, reflecting relatively strong upwelling in the studied region, and suggesting a contribution to the enrichment of Globigerinids in the sediments. The Benthic foraminiferal assemblage (Melonis pompilioides-Bulimina costata-Pullenia bulloides-Oridorsalis umbonata) reflects a typical bathyal environment, and a paleo-water depth of approximately 1000 m was reconstructed based on the quantitative analysis. The occurrence of epi-benthic species Cibicides lobatulus, suggests the presence of a regional westward bottom current. Based on the paleoceanographic reconstruction, a bottom-current-influenced, high-productivity foraminiferal model is proposed to explain the formation mechanism of the Globigerinid-rich limestone in this region. Highly productive planktonic foraminifers were deposited on a paleo-topographic high in a bathyal/middle slope environment, while relatively strong bottom current winnowed away most fine-grained foraminifers and clay minerals, resulting in sedimentary drift (contourite) formation and ultimately producing the Globigerinid-rich limestone reservoir.
