The occurrence of taxa typically associated with Gondwana, in what is now the Northern Hemisphere, remains an intriguing subject in paleobiogeography. We describe an unusual tree fern from mid-Cretaceous amber in Myanmar, classified in the genus Lophosoria (Dicksoniaceae, Cyatheales). Its classification within the extant genus Lophosoria is supported by distinctive morphological features of the fertile pinnule, notably its unique flanged spores. Currently, Lophosoria is restricted to the Neotropics and southern South America, with prior paleopalynological and megafossil data indicating its exclusive presence in the Southern Hemisphere, particularly in Eastern Australia, the Falkland Plateau, South America, and the Antarctic Peninsula, suggesting a Gondwanan origin. The identification of the new species in mid-Cretaceous Northern Hemisphere deposits marks the genus's earliest confirmed occurrence in this region, broadening our understanding of its historical distribution and early evolution. This discovery contributes to the recognized diversity of Lophosoria, which has largely been based on spore fossils linked to the genus Cyatheacidites. We also discuss the paleobiogeographic and paleoclimatic implications for the evolutionary history of Lophosoria.

Ichthyodectiformes are a fossil teleostean lineage originating from the Middle Jurassic to Early Cenozoic period, found in marine and freshwater sediments on every continent. The clade is supported by five synapomorphies and is currently known to exist in over 30 valid species. However, most fossils are poorly preserved or incomplete, and therefore, the synapomorphies for this group are hard to identify or are even homoplastic in many teleostean lineages. This identification problem is recognized, and many authors highlight a combination of characteristic anatomic aspects to identify this group, like the distinctive “bulldog-like” head shape. In Brazil, Ichthyodectiformes are represented by six valid nominal genera (Saurocephalus, Chiromystus, Itaparica, Ogunichthys, Cladocyclus, Cladocynodon) temporally distributed in the Cretaceous period, exclusively on the northeastern sedimentary basins (Araripe, Parnaíba, Recôncavo-Tucano-Jatobá, and Sergipe-Alagoas). Despite these known forms, to this day, there is no comparative anatomical work between the Brazilian species. This work aims to conduct a comparative anatomical and phylogenetic study of Cretaceous species from Brazil to better understand the their interrelationship based on the data available for the taxa in question. The specimens were reviewed by comparative anatomy and analyzed using the program PAUP* 4.0a169 based on the last data matrix to test the intrarelationships of Ichthyodectiformes. Based on the anatomical review, characteristics for the taxa were updated. Compared to the previous results, our analysis resulted in a large polytomy, with no clear affinities for Cladocynodon araripensis, and the relationship between Ichthyodectiformes from Brazil remains unclear. The available material in the collections was insufficient to elucidate the relationships of the Brazilian species. Only the synapomorphies of teeth in a single series and a ventrally enlarged coracoid could be verified in every taxon. A larger sampling effort is recommended to elucidate the phylogeny.

Ichnotaxonomy is the naming and classification of trace fossils based on their morphological features, which incorporate tracemaker anatomy, behaviour, and substrate. Unlike traditional taxonomy, it is a parataxonomic system whereby ichnotaxa are named independently of the animal that produced them. Tetrapod ichnotaxonomy was established by Edward Hitchcock, who applied Linnaean binomial nomenclature to the naming of dinosaur tracks. Today, ichnotaxonomy follows rules established by the International Code of Zoological Nomenclature.

Historically, tetrapod ichnotaxonomy has struggled with inconsistent descriptive standards, nomenclatural issues, a legacy of producer-focused naming, and a reliance on qualitative methods. Efforts have been made to standardise tetrapod ichnotaxonomy, especially since the vertebrate ichnology “renaissance”, and several scholars have provided guidelines to streamline the practice and for its greater utility in palaeobiological and palaeoecological studies. Nonetheless, subjective interpretation is common, and the incorporation of quantitative methods is not consistent. A conceptual divide concerns preservation bias and the definition of “preservation” in tetrapod ichnology. Preservation can relate to anatomical fidelity (morphological preservation) and thus be diagnostic for ichnotaxonomy, while an alternative view defines preservation in terms of post-formation modification. This perspective treats formation variation from foot–sediment interaction and behaviour as distinct from taphonomic loss. These approaches differ on when taphonomy begins.

The need to separate formational from post-formational variation to combat ichnotaxonomic inflation is illustrated by several case studies in the literature, including ongoing reassessments of historically oversplit ichnotaxa and morphometric analyses of conservative track morphologies. By defining and assessing preservation, applying standardised methods, and considering ichnotaxonomic decisions within morphological, sedimentological, and behavioural contexts, tetrapod ichnology can be holistic, ensuring that what we name aligns with what we can know.

Tullimonstrum gregarium is an enigmatic soft-bodied fossil from the Pennsylvanian Mazon Creek Lagerstätte of Northern Illinois. It was originally described by Richardson (1966) as problematica, but is listed as a worm-like animal in the title. Since this initial description, researchers have struggled to classify the 30 cm long fossil. Cladistic analyses have placed it within the clade uniting vertebrates, molluscs, annelids, and nemerteas.

Recently, these fossils have been subject to renewed testing and analysis. McCoy et al. (2016) assigned it to the Agnathans based on identifying a notochord, gill pouches, and w-shaped myomeres. They further supported this assignment with synchrotron analysis of trace element enrichment in the fossil. A vertebrate assignment was indicated by the discovery of melanosome structures in the eyes using SEM (Clements et al. 2016). In situ Raman microspectroscopy showed evidence that the structural tissue was made of proteins and not chitin, providing strong evidence for a vertebrate assignment (McCoy et al. 2020).

Mikami et al. (2023) examined surface features on the fossils using a 3D laser scanner, conducted X-ray microcomputed tomography scans of the teeth-like structures, and suggested that some features in the head represent preserved segments; they argued that the combination of features they observed is most consistent with a non-vertebrate chordate classification.

The use of new technologies and innovative methods to classify Tullimonstrum gregarium has resulted in new ideas about its origin, but researchers still disagree on its identity and even on its morphology. However, research continues, including a current investigation of its structural tissues using scanning electron microscopy, and each project provides new data that brings us closer to a final answer to this mystery.

References

Clements T, Dolocan A, Martin P, Purnell MA, Vinther J, Gabbott SE. The eyes of Tullimonstrum reveal a vertebrate affinity. Nature. 2016 Apr 28;532(7600):500-3. doi: 10.1038/nature17647.

McCoy VE, Saupe EE, Lamsdell JC, Tarhan LG, McMahon S, Lidgard S, Mayer P, Whalen CD, Soriano C, Finney L, Vogt S, Clark EG, Anderson RP, Petermann H, Locatelli ER, Briggs DE. The 'Tully monster' is a vertebrate. Nature. 2016 Apr 28;532(7600):496-9. doi:10.1038/nature16992. Epub 2016 Mar 16. PMID: 26982721.

McCoy VE, Wiemann J, Lamsdell JC, Whalen CD, Lidgard S, Mayer P, Petermann H, Briggs DEG. Chemical signatures of soft tissues distinguish between vertebrates and invertebrates from the Carboniferous Mazon Creek Lagerstätte of Illinois. Geobiology. 2020 Sep;18(5):560-565. doi:10.1111/gbi.12397. Epub 2020 Apr 28. PMID: 32347003.

Mikami T, Ikeda T, Muramiya Y, Hirasawa T. Iwasaki W.Three-dimensional anatomy of the Tully monster casts doubt on its presumed vertebrate affinities. Palaeontology. 2023 66: e12646. doi.org/10.1111/pala.12646

Richardson, ES Jr. Wormlike Fossil from the Pennsylvanian of Illinois. Science. 1966 151, 75-76. doi:10.1126/science.151.3706.75.b

The Paraíba–Pernambuco Basin, located between Recife and Mamanguape, Northeastern Brazil, is notable for its remarkable Mesozoic chondrichthyan fauna and its critical role in the geological evolution of the South Atlantic. Geological evidence indicates that this basin was among the last regions to separate during the fragmentation of Gondwana. The fossil assemblages preserved in this area hold global significance for paleontological research, particularly in relation to the evolution and paleobiogeography of elasmobranchs throughout the Cretaceous period. This study aims to provide an anatomical and taxonomic redescription of the chondrichthyes from the Paraíba–Pernambuco Basin, based on dentition and its morphological variations. A total of 128 fossil chondrichthyan teeth from the Itamaracá (Campanian–Maastrichtian), Gramame (Maastrichtian), and Maria Farinha (Paleocene) formations, housed in scientific collections at Brazilian universities, were examined, some of which have been described in earlier studies. Anatomical and taxonomic assessments were conducted based on criteria such as main cusp angulation, the number of accessory cusps, crown shape and size, the presence of serrations, and overall proportions. Additionally, morphological comparisons with living species were employed to infer the original tooth position within the jaw. The morphological analyses enabled the identification of the specimens and the reconstruction of their jaw positioning, thereby enhancing our understanding of elasmobranch jaw architecture. Taxonomic revisions included the reclassification of Notidanus microdon as Hexanchus microdon, Odontaspis tingitana as Carcharias tingitana, and the reassignment of all previously identified Lamna species to the genus Cretolamna. Notably, Ptychodus whipplei was recorded for the first time in the Itamaracá Formation, extending its known geographic distribution. The findings underscore the value of integrating fossil and living morphological data to refine taxonomic identifications. Moreover, the Paraíba–Pernambuco Basin is reaffirmed as a key fossil locality for elucidating elasmobranch diversity and biogeography during the Mesozoic period. This study contributes valuable insights for future taxonomic and paleoecological investigations in the region.

Taiwan, with its rich biodiversity since the Neogene period, has been the subject of extensive paleontological research; however, studies of its molluscan fossil fauna remain outdated. Contemporary gastropod diversity in the surrounding waters is considerably higher than that reflected in Quaternary deposits, suggesting that certain Pleistocene gastropod groups may have been undersampled or overlooked. To evaluate potential gaps in the Pleistocene mollusk record, we examined bulk sediment samples from two strata of the Toukoshan Formation (northern Taiwan) and the Szekou Formation (southern Taiwan). We focused on small gastropods (<5 mm), which may have been neglected in previous investigations. Specimens were sorted, identified to the lowest possible taxonomic level, and compared with both fossil and modern reference collections. We identified more than 150 taxa previously unreported from the Taiwanese Pleistocene record. These include representatives of Patellogastropoda; Vetigastropoda (≥4 families, 1 newly recorded family); Neomphaliones; Caenogastropoda (≥9 families, 5 newly recorded); and Heterobranchia (≥5 families, 4 newly recorded, and 1 newly recorded order). Several taxa represent their first occurrence as fossils, thereby extending their known geological ranges. Notable findings include pelagic Littorinimorpha and Pteropoda, as well as Cephalaspidea specimens potentially representing new species. Our results reveal a substantially richer and more diverse Pleistocene molluscan assemblage than previously recognized in Taiwan. These findings improve assessments of Late Pleistocene species richness, facilitate comparisons with the modern Indo–West Pacific fauna, and contribute to understanding the timing of lineage appearances in the region. The expanded fossil inventory will also enhance future paleoecological and biogeographical reconstructions, shedding light on the processes underlying the establishment of present-day Indo–West Pacific marine biodiversity.

The Megara Basin in Greece, located east of the Corinthian Gulf and bordered by the Alkyonides Gulf to the north and the Saronic Gulf to the south, comprises Neogene-Quaternary formations rich in marine and lacustrine fossil mollusks. The shell morphology of T. micans closely resembles that of both fossil and extant taxa, notably Theodoxus meridionalis, a species that is widely distributed throughout the Mediterranean region, including Greece. However, substantial intraspecific variability in shell shape and coloration among Theodoxus species complicates taxonomic assignments. Conversely, the operculum has been recognized as a potentially more reliable feature for species-level differentiation. Our research draws on material from the historical collection of the Museum of Geology and Paleontology at the National and Kapodistrian University of Athens (NKUA), which includes fossil specimens and sediment samples from sites such as Alepochori and the Mauratza Ravine. This material consists of both bulk fossiliferous sediments and previously sorted fossils from the 20th-century research. We discovered opercula, which were identified as belonging to T. micans. These were found alongside T. micans shells and other species such as Lymnaea megarensis Gaudry, 1867, but no other Theodoxus species. Comparative analysis with extant and fossil material from other localities—where T. micans has been reported—yielded no prior operculum descriptions. Our findings suggest that T. micans may be conspecific with or closely related to T. meridionalis. These results contribute to the ongoing taxonomic and systematic reassessment of this fossil taxon.

Solenogastres (Mollusca, Aplacophora) are small, worm-shaped marine molluscs that are often overlooked in biodiversity studies, despite their widespread distribution across all oceans and depths. Many species exhibit intimate ecological relationships with other invertebrates, particularly colonial cnidarians but also sponges, which they use as hosts and food sources. Ecological associations often drive adaptation and speciation. For instance, species that rely on obligate symbiosis tend to have smaller populations, limited dispersal, and fragmented habitats, making them more vulnerable to environmental stress and extinction. Thus, studying associations in Solenogastres is essential to understand their evolution and resilience. Moreover, corals and sponges are vital components of benthic ecosystems and are highly sensitive to environmental changes. However, due to challenging taxonomy and historically limited sampling, the nature and specificity of these interactions remain poorly documented. This mirrors a broader lack of data on the biogeography and species documentation of solenogasters. Therefore, building a robust taxonomic framework for Solenogastres is critical, not only to resolve their diversity, but to illuminate the ecological and evolutionary implications of their symbiotic lifestyles. Here, we present a synthesis of what is currently known about solenogaster-host relationships, based on an extensive literature review, alongside preliminary results from ongoing morphological and molecular studies. Our integrative approach combines ecological observations with molecular and morphological approaches to improve species delimitation and host identification. This work lays the foundation for a more comprehensive understanding of Solenogastres ecology and evolution in a changing ocean.

The Jura region (France and Switzerland) is a key area for studying Late-Jurassic (Kimmeridgian–Tithonian) dinosaur tracks. Cyclical fluctuations in sea levels during this period exposed the Jura carbonate platform, creating land bridges that facilitated the dispersal of vertebrates and the formation of track-bearing surfaces. As a result, there are numerous tracksites in both countries. They exhibit well-preserved tracks with strong morphological similarities and possible ichnotaxonomical affinities. Dinosaur ichnotaxonomy is based primarily on morphological rather than behavioural characteristics, and in many studies, the correct attribution of footprints to specific ichnotaxa has been problematic. In this study, we propose classifying Plagne theropod tracks in Megalosauripus transjuranicus through a quantitative approach, using two landmark-based analyses: Geometric Morphometrics (GM) and Whole-Track Analysis (WTA). Our results reveal clear clustering in morphospace for GM and morphological overlap in the WTA, supporting this attribution. Utilizing a dataset including other Jurassic theropod ichnotaxa, new ichnotaxonomical affinities have been revealed. This study records the presence of M. transjuranicus in the French Jura and highlights the utility of this approach in ichnotaxonomical identification. Furthermore, it extends the known stratigraphic range of Megalosauripus transjuranicus into the Tithonian in France and up to the Berriasian in Spain, suggesting a longer persistence than previously documented for large theropods in these areas.

Fossils of the family Conidae (predatory marine gastropods) present persistent taxonomic challenges due to limited morphological variability between species and the often-overlooked potential of shell colour patterns. Consequently, certain historical classifications from the 19th century, many of which remain in use today, include ambiguous or potentially redundant taxa. During a short-term scientific mission to the Museo Regionale di Scienze Naturali di Torino (Italy), I studied over 180 Neogene Conidae specimens, including the 35 type specimens originally described by Federico Sacco, which are hosted in the museum. Sacco’s many named varieties, known for their taxonomic uncertainty, were also partially assessed. Ultraviolet (UV) light imaging was used to reveal residual shell colour patterns that are not visible under natural light. Preliminary results display that some species or varieties likely represent multiple distinct taxa, while some varieties are distinct species. For example, Conus (Kalloconus) berghausi (Michelotti, 1847), including the neotype and Sacco’s varieties, appears to encompass at least three separate species. UV imaging proved particularly useful in detecting consistent colour pattern elements that support species delimitation. This initial assessment illustrates the potential of combining UV imaging with classical morphological approaches to refine the taxonomy of Neogene Conidae. Further detailed study of Sacco’s broader collection may yield additional taxonomic insights and contribute to a more stable framework for interpreting fossil cone snail diversity.