Fossil Studies

Thailand preserves one of the most extensive records of Mesozoic vertebrate tracks in Tropical Asia, yet these ichnological data have never been comprehensively synthesized. This review compiles and reassesses all known Triassic to Cretaceous vertebrate tracksites in Thailand to clarify their stratigraphic distribution, taxonomic diversity, and palaeobiogeographical significance. Published records, new field observations, and updated stratigraphic correlations are integrated to evaluate trackmaker attributions and temporal patterns. The Thai record documents diverse assemblages including chirotheriids, early theropods, sauropodomorphs, ornithopods, sauropods, and crocodilians. Late Triassic–Early Jurassic assemblages capture a major faunal transition, revealing the co-occurrence of non-dinosaurian archosaurs and some of the earliest dinosaurs in the region, whereas Lower Cretaceous sites are dominated by theropods, sauropods and diverse ornithopods. Comparison with other Asian ichnofaunas indicates faunal continuity across eastern Asia and supports early dinosaur dispersal into equatorial low latitudes. This synthesis also evaluates site conservation, highlighting the vulnerability of several Triassic localities and a positive trend of community-led discoveries since 2009, underscoring the need for proactive management and standardized digital documentation. Overall, the Thai ichnological succession represents the most complete Mesozoic track record presently known from Tropical Asia and provides key insights into vertebrate evolution, palaeoecology, and regional biogeography. Full article

Trackways preserve sequential records of animal locomotion and provide some of the most direct evidence of locomotor behaviour in the vertebrate fossil record. Alternating short–long pace lengths have historically been used to infer gait irregularities such as limping or lateral limb preference, but these interpretations typically lack statistical validation, treating mean asymmetry as sufficient grounds for behavioural conclusions without first establishing whether observed differences exceed normal locomotor variability. This study introduces a quantitative framework that addresses this gap by applying Welch’s t-test to pace and stride length measurements, establishing statistical confirmation of asymmetry as a prerequisite for behavioural interpretation. The framework is demonstrated on nine dinosaurian trackways drawn from published data. While all had previously been interpreted as asymmetric, seven exhibited statistically significant pace asymmetry (p < 0.05) and two did not exceed the range of normal variation. Stride length showed no significant asymmetry in any trackway, confirming that pace-level metrics are more sensitive to limb bias than stride-based measures. This framework provides an objective, reproducible standard for evaluating asymmetry claims—a necessary and feasible methodological advance for vertebrate ichnology. Full article

Mesozoic tree ferns related to the extant Loxsomopsis, a relict and taxonomically isolated genus endemic to tropical South America, are exceedingly rare, making it difficult to trace its origin and evolution. Here, we describe a mid-Cretaceous fossil attributable to Loxsomopsis, Loxsomopsis minor sp. nov., based on two fertile pinnules preserved in Myanmar amber. The new species is assigned to the extant genus based on a suite of diagnostic features, including pinnate fertile segments with short lobes, marginal paraphysate sori, narrowly cyathiform to urceolate indusia, columnar and exserted receptacles, oblique sporangial annuli, and trilete spores. This discovery extends the fossil record of Loxsomopsis back to the Albian–Cenomanian and provides new evidence that the lineage—now restricted to tropical South America—was once more widespread. The occurrence of Loxsomopsis in the Myanmar amber biota is consistent with a Gondwanan affinity for this mid-Cretaceous forest ecosystem and suggests that the genus may have likely originated prior to the breakup of Pangaea. Full article

This research provides a new comprehensive assessment of Pikimachay Cave fossil remains of extinct fauna from the Late Pleistocene and Early Holocene, curated in the Florida Museum of Natural History’s Environmental Archaeology Program collections. The collection is the result of excavations carried out by Richard MacNeish during the 1960s and 1970s, during which he proposed pre-Clovis dates for human occupation in South America. Archival records housed across three institutions were compiled to reconstruct the spatial distribution of megafauna within the cave. Taphonomic observations of the bone assemblage were conducted to better understand depositional processes and cave conditions. Based on the spatial distribution of fossil evidence mapped and documented by layer and the taphonomic evidence of the bone assemblage, we conclude that the cave functioned primarily as a giant ground sloth burrow, also used by humans and carnivores. Future research, including additional radiocarbon dates and better contextualization of the deposits, will be essential for better understanding the fossil fauna represented in the cave and the ecological relationships among humans, carnivores and extinct species in the highlands of Perú. Full article

Nanxiong Basin (Guangdong Province, southern China) preserves one of the most complete nanhsiungchelyid turtle records from the latest Cretaceous in Asia. In this study, we review nanhsiungchelyid remains recorded from Nanxiong Basin within a refined stratigraphical framework. Nanhsiungchelyids show constant occurrence in the Nanxiong Basin, recorded from most formations of the Nanxiong Group, with their probable last occurrence close to the Cretaceous–Paleogene boundary. Full article

The Cretaceous dinosaur record from Normandy, in NW France, is reviewed. It includes several enigmatic specimens that were briefly mentioned in short notes published during the 19th and 20th centuries that have since then been destroyed in World War II or lost. Since they were neither described in detail nor illustrated, their identification must remain uncertain, but some may have been ankylosaur remains, while another specimen may have belonged to a bird or a non-avian theropod. Specimens that were properly described and are kept in museums in Normandy come from Albian and Cenomanian horizons in the coastal cliffs of Seine-Maritime. The Albian record, from Cape La Hève (Le Havre) includes an incomplete titanosaurian sauropod skeleton, described as Normanniasaurus genceyi, and an isolated caudal vertebra from the same provenance, probably belonging to that taxon. The Cenomanian record is limited to a group of bones and a tooth of the furileusaurian abelisaurid theropod Caletodraco cottardi from the glauconitic Chalk at Saint-Jouin-Bruneval. All these specimens come from marine sediments and are in all likelihood derived from floating carcasses that drifted over a fairly long distance from an emergent land area corresponding to the Armorican massif in the west. Although scanty, the record from Normandy sheds some light on the poorly known dinosaurs that inhabited north-western Europe during the middle part of the Cretaceous, some of which apparently had Gondwanan affinities. Full article

Palynological analysis of seventy-seven cutting samples from six boreholes in the Marañón Basin (northeastern Peru) has identified five distinct Neogene marine incursion events (ME-1 to ME-5), challenging existing models that depict them as short-lived episodes. The diverse palynological assemblages, comprising spores, pollen, freshwater algae, and critical marine indicators—including dinoflagellate cysts, foraminiferal test linings, and copepod eggs—reveal that these incursions were protracted and recurrent, each associated with a maximum flooding surface and bounded by intervals of continental sedimentation. The stratigraphic record shows the earliest event ME-1 (Aquitanian to Late Burdigalian, 23.03–17.7 Ma) identified across all studied wells. ME-2 (latest Burdigalian to Middle Langhian, 17.0–16.1 Ma) is also recorded basin-wide. ME-3 (latest Burdigalian to earliest Langhian 16.5–15.7 Ma) registered in two wells. ME-4 (Late Langhian to latest Serravallian, 14.6–11.62 Ma) registered in only two wells and ME-5 (Early Tortonian, 11.6–10 Ma) is documented exclusively in the southernmost well, culminating in Zanclean (~5.5–3.6 Ma) mangrove development. We interpret the ingress routes for ME-1 to ME-3 to be westward via the Marañón Portal or northward from the Caribbean, associating them with the Proto-Pebas and Pebas systems. In contrast, ME-4 would also be from Amazon trunk or Paraná Portal associated with the Pebas Phase, and ME-5 likely originated from the south through the Paraná Portal, linking it to the Acre Phase. These results demonstrate that Miocene marine incursions into western Amazonia were not brief episodes but represented prolonged periods of marine influence, facilitated by sustained subsidence in the Marañón retro-arc foreland basin. This history reveals a dynamic connectivity throughout the Neogene, with marine conditions acting as persistent biogeographic barriers that critically shaped the region’s Miocene biodiversity patterns. This refined chronology provides a comprehensive regional framework, significantly advancing our understanding of Amazonian paleogeography. Full article

Microscopes have long been an important tool for paleontology, but most researchers use biological microscopes that are designed for transmitted light illumination. Micropaleontology has traditionally involved investigations of individual organisms (e.g., foraminifera, radiolarian and diatoms), or fossil pollen. Optical microscopy can also be a useful method for the study of macrofossils. Polarized light illumination, long a mainstay of geological research, has largely been missing from paleontology investigations. However, adapting a standard microscope for polarized light is not a difficult task. The preparation of mineralized fossils as petrographic thin sections greatly expands the possibilities for microscopic examination of macrofossils. Scanning electron microscopy (SEM) has long been used for the study of fossils, most commonly for observing individual microfossils or anatomical features of larger organisms. X-ray fluorescence analysis (SEM/EDS), a standard method for geology research, has had minimal use by paleontologists, but it is a method that merits wider acceptance. This paper emphasizes inexpensive methods for researchers who want to expand their microscopy horizons without needing deep funding or access to specialized facilities. Full article

Marine deposits in western Europe provide insight into the interplay between the warm Tethys and cooler Boreal domains, offering a climatic context for the radiation of Early Jurassic species. Reconstructions of temperature for the Hettangian and Sinemurian periods are scarce, with inferred marine temperatures of 15–20 °C based on δ¹⁸O values, which are lower than those of subsequent Jurassic stages. This emphasizes the necessity for supplementary data in order to enhance our comprehension of the climatic dynamics that characterized the Early Jurassic period. This study analyses 75 invertebrate samples, including 53 specimens of Gryphaea arcuata, from Early Sinemurian marine sediments in the Fresville quarry, Normandy, France. The present study employs a multi-proxy approach, utilizing δ¹³C and δ¹⁸O values in conjunction with Sr and Mg contents, to assess the processes of fossil diagenesis, marine productivity, and seawater temperatures. Significant post-depositional alteration was observed in the geochemical compositions of 22 bivalve shells assigned to the genera Pseudolimea, Plagiostoma, and Chlamys, which were originally composed of aragonite, except for the outer layer, which is made of calcite. However, the low-Mg calcite shells of Gryphaea arcuata, which are renowned for their diagenetic resistance, retained the majority of their isotopic integrity. The results of the statistical analyses indicate that there was minimal late pervasive diagenesis involving meteoric waters at Fresville. This is in accordance with the typical decrease in δ¹³C, δ¹⁸O values, and Sr and Mg contents that such processes would otherwise cause. Published isotopic data from Sinemurian marine fossils (plesiosaur and shark teeth) were used to estimate seawater δ¹⁸O (~−1‰ VSMOW) and surface temperatures (~24 °C). The calculated benthic temperatures of Gryphaea (17 °C) correspond to habitats at depths of about 50 m. These findings suggest a positive hydrological balance and euhaline conditions in a humid tropical climate context. Full article

New theropod tracks found in the Papo-Seco Formation (lower Barremian, Lusitanian Basin, Portugal) are presented. In 2022, thirteen theropod tracks were identified on the lowermost bed of this formation, preserved as natural cast infillings on the bedding surface. Two different morphotypes of theropod footprints have been identified, which occur at two different levels of this layer. The first morphotype, consisting of smaller footprints with narrow digits, is attributed to theropoda indet; the other morphotype, consisting only of one footprint, is assigned provisionally to the ichnogenus Megalosauripus isp. It is suggested that they were produced by medium-sized theropods, on a carbonate mud substrate, probably in a coastal environment associated with a lagoon. These tracks, and others previously described in the underlying Areia do Mastro Formation, suggest a temporal continuity of the groups of dinosaurs that frequented this area, during the early Barremian. However, the morphotypes now described differ from those of the theropods tracks from the Areia do Mastro Formation, which may indicate a change in faunal types within the theropod group. Full article

During the Late Miocene, Bramatherium was the main representative of the giraffid subfamily Sivatheriinae in the Indian Subcontinent, with sparse and uncertain records from adjacent regions. In the present paper, we describe and compare two ossicones of the same individual, unearthed from the Upper Miocene site of Fourka in Chalkidiki Peninsula, Northern Greece, and attribute them with certain confidence to the species Bramatherium perimense. The definite record of Bramatherium so far away from the Indian Subcontinent and in close proximity to the well-known Pikermian sivatheriine Helladotherium duvernoyi enabled us to re-discuss both the intrageneric diversity of Bramatherium and the debatable Bramatherium–Helladotherium taxonomy. Our review allows us (i) to recognize only two Bramatherium species in Asia: the large-sized B. grande and the smaller B. perimense and (ii) to confirm and further support with morphological and biogeographic evidence the synonymy of Helladotherium with Bramatherium. Full article

Coelacanths in the Family Mawsoniidae include ten genera with a primarily Gondwanan distribution. Two of the genera—Mawsonia and Axelrodichthys—show a related biogeographic pattern of occurrences in the Cretaceous of Brazil and Africa. This report documents the presence of Axelrodichthys in the Early Cretaceous of Niger based on a partial skull roof and partial extrascapular series from the Aptian ‘Fish Mountain’ site at Ingal (or Ingall) in central western Niger. Assignment of the specimen to Axelrodichthys is based on the presence of a median extrascapular along the posterior margin of the skull roof, an element that is absent in the sister-genus Mawsonia. This record from Niger fits into the broader pattern of the genus co-occurring in both northeastern Brazil and northwestern Africa, and then subsequently expanding its range across Africa during the Cretaceous—reaching Niger at an intermediate stage—and then eventually dispersing as far east as Madagascar and as far north as what is now southern Europe by the Late Cretaceous. Full article

At 47° S in Argentine Patagonia, the interaction between the Southern Westerly Winds (SWW) and the Andean barrier generates a steep climatic gradient, providing an ideal setting to evaluate Holocene vegetation responses. This study focuses on the extra-Andean sector, where new pollen records from La Tapera (LTap) and Cisne 7 provide insights into steppe vegetation dynamics under dry conditions. These sequences are contrasted with previously studied records further west (LF, ZB, CMN1, CMN2, and COCU) to assess west–east gradients in vegetation change and moisture availability throughout the Holocene. Western records indicate that the Early Holocene was dominated by grass–dwarf-shrub steppe under arid conditions, followed by increased humidity around 7600 cal yr BP that promoted the development of forest–steppe ecotonal environments. The Middle Holocene was characterised by aridity, reflected in shrub dominance and reduced forest signals, whereas the Late Holocene included a humid pulse between ~1750 and 1000 cal yr BP, followed by renewed aridity over the last millennium. In contrast, eastern records show persistent shrub–dwarf-shrub steppes since ~4700 cal yr BP, with vegetation changes expressed mainly as shifts in the relative dominance of shrubs and dwarf–shrubs rather than floristic replacements. Archaeological sites corroborated and complemented the continuous records, strengthening the reconstruction of environmental variability across different temporal windows. Overall, this west–east comparison highlights the differential sensitivity of ecosystems to SWW fluctuations, reinforcing their role as an important forcing of hydrological balance and vegetation dynamics in mid-latitude Patagonia. Full article

Onychophora (velvet worms) are rare, soil-dwelling invertebrates with a fragile body structure that limits their fossil record. Their current distribution across the Neotropics has long been shaped by vicariance and dispersal events. Here, we evaluate the hypothesis that the Cretaceous–Paleogene (K–Pg) asteroid impact played a role in shaping the modern biogeography of Onychophora by eliminating lineages within the affected zone. Using published molecular phylogenies and geological data on the Chicxulub impact, we assess whether extant clades are congruent with a post-impact recolonization scenario. We find that several clades have divergence dates incompatible with extinction at the K–Pg boundary and that current distributions do not show a clear biogeographic signature consistent with impact-induced extirpation. Our hypothesis test supports the survival of onychophoran lineages through the K–Pg event and calls for caution in attributing modern distributions to a single extinction event without integrating molecular, stratigraphic, and ecological data. Full article

Geological data of the region indicate that the Canary Islands have not been connected to the mainland before. However, fossil evidence suggests some kind of faunal exchange with Africa during the late Neogene. After extensive field work during past years, a re-evaluation of the fossil remains of the first terrestrial vertebrates that settled and thrived on the Canary Islands is presented, with special attention to the long-debated identity of birds that laid large-sized eggs, reported some decades ago on Lanzarote Island. The age of the eggshell-bearing deposits has been recently updated as Early Pliocene (ca. 4 Ma). The dispersal mode of these terrestrial birds to reach the island was an unsolvable challenge in previous studies because the regional geography of the sea bottom was neglected, as well as the chronological succession of events in the formation of the Canary Eastern Ridge, which increased attention to a unique case of arrival of ratites on an island never before united with the mainland. The few animals found in northern Lanzarote (ratites, snakes, turtles, terrestrial snails and bite marks on eggshells pointing to a jagged and unknown large predator) probably made the sea crossing from the mainland in different ways. Two scenarios are contemplated. In both, the circumstances facilitating the faunal transit from Africa to the Canaries ceased after the early Pliocene, around 4 Ma, since these animals have never managed to cross the Canary Channel again. Full article

Cranial kinesis in Neornithes is enabled by a complex system of bones, muscles, ligaments, and joints, allowing variable degrees of movement between the upper jaw and the neurocranium. Particularly, cranial prokinesis—mobility of the upper jaw relative to the neurocranium—is the most widespread form. It has been stated that Phorusrhacidae (Aves, Cariamiformes) were incapable of performing cranial kinesis. To assess potential functional differences within the clade, all known cranial flexion zones were analyzed and compared with the kinetic systems of extant Neornithes. In Psilopterinae and Mesembriornithinae, fusion of the ventral palatal flexion zones indicates a rigid, immobile palate. In larger taxa such as Patagornithinae and Phorusrhacinae, the pronounced thickening and fusion of the craniofacial flexion zone confirms the loss of prokinetic capabilities. The functional implications of such akinesis include simplification of food processing and a significant increase in bite force, which correlates with the predatory skills of the group. In a phylogenetic framework, phorusrhacids evolved from a kinetic ancestral condition, representing the only truly akinetic group among Neornithes. Full article

Fossil resins from the area of Gulf of Gdańsk, Lublin area, Denmark, Bitterfeld, Lusatia and Ukraine, often grouped under the collective term ‘Baltic amber’, are complex organic mineraloids that have undergone various post-depositional transformations. Despite their role in paleontology as a source of for biological inclusions, fossil resins themselves are rarely analyzed as taphonomic objects. In this work, a new geochemical approach to fossil resin taphonomy is presented. Applying the van Krevelen diagram—traditionally used for kerogen classification—allows the diagenetic and catagenetic changes of fossilized resin maturation to be evaluated. Based on literature-derived elemental composition data of C, H, and O contents of ‘Baltic amber’, the diagram is interpreted as an organic matter transformation framework of fossil resins. The results suggest that the so-called ‘Baltic amber’ deposits represent a composite taphocoenoses of resins with different burial histories and maturation scenarios. This approach integrates petrological classification, geochemical maturation, and taphonomic analyses, offering a new way of “tracking” fossil resins maturation changes. Full article

This study conducted a spatiotemporal review of the coelacanth fossil record and explored its distribution and diversity patterns. Coelacanth research can be divided into two distinct periods: the first period, which is based solely on the fossil record, and the second period following the discovery of extant taxa, significantly stimulating research interest. The distribution and research intensity of coelacanth fossils exhibit marked spatial heterogeneity, with Europe and North America being the most extensively studied regions. In contrast, Asia, South America, and Oceania offer substantial potential for future research. Temporally, the coelacanth fossil record also demonstrates significant variation across geological periods, revealing three diversity peaks in the Middle Devonian, Early Triassic, and Late Jurassic, with the Early Triassic peak exhibiting the highest diversity. With the exception of the Late Devonian, Carboniferous, and Late Cretaceous, most periods remain understudied, particularly the Permian, Early Jurassic, and Middle Jurassic, where the record is notably scarce. Integrating the fossil record with phylogenetic analyses enables more robust estimations of coelacanth diversity patterns through deep time. The diversity peak observed in the Middle Devonian is consistent with early burst models of diversification, whereas the Early and Middle Triassic peaks are considered robust, and the Late Jurassic peak may be influenced by taphonomic biases. The low population abundance and limited diversity of coelacanths reduce the number of specimens available for fossilization. The absence of a Cenozoic coelacanth fossil record may be linked to their moderately deep-sea habitat. Future research should prioritize addressing gaps in the fossil record, particularly in Africa, Asia, and Latin America; employing multiple metrics to mitigate sampling biases; and integrating a broader range of taxa into phylogenetic analyses. In contrast to the widespread distribution of the fossil record, extant coelacanths exhibit a restricted distribution, underscoring the urgent need to increase conservation efforts. Full article