The James Ross Basin, situated in the northwestern portion of the Antarctic Peninsula, holds one of the most complete sedimentary records of the Cretaceous, and hosts exceptionally well-preserved and diverse fossil assemblages, particularly notable for high southern latitudes. The Santa Marta Formation (Santonian–Campanian) harbors a rich decapod crustacean fauna, including Anomura, Astacidea, Achelata, Brachyura, and Glypheidea. Among brachyuran crabs, only four families have been described on James Ross Island: Homolodromiidae, Necrocarcinidae, Prosopidae, and Raninidae. This work focuses on a brachyuran from the Marambio Group, a part of the Santa Marta Formation. The material presented here was collected during the 41st Brazilian Antarctic Operation by researchers of the PALEOANTAR project. The site consists of a sequence of intercalated volcanic sandstones, siltstones, and tuffs, interpreted as a set of volcanoclastic deposits formed in a deltaic environment. The specimen described here with a well-preserved ventral surface, Sabellidromites santamarta new species, is assigned to the Dynomenidae based on uropods as calcified dorsal plates, a reduced, obliquely subdorsal fifth pereopod (fourth pereopod not reduced), and characteristics of the dorsal carapace. The occurrence of Sabellidromites santamarta n. sp. in the Santonian–Campanian of Antarctica suggests biogeographic exchanges of the dynomenid fauna between the Northern and Southern hemispheres during the Late Cretaceous.

UUID: http://zoobank.org/5c53c84a-af78-432f-ba1a-795008a3db70

Fossil crinoids from the Ordovician–Silurian boundary interval (~ 443.8 million years) are known from relatively few locations worldwide due to a near-global unconformity that formed from eustatic sea-level fall. This rock record bias has severely hindered study of the timing, magnitude, biogeographic signature, and extinction mechanisms of the Late Ordovician mass extinction (LOME). Crinoids underwent a significant faunal transition between the Late Ordovician and early Silurian that resulted in major shifts between dominant clades, but the driving mechanisms and precise timing of this transition remain unclear. Anticosti Island (Québec, Canada) preserves one of the few Late Ordovician–early Silurian successions of highly fossiliferous, shallow-water rocks that includes the Ordovician–Silurian boundary, making fossils from this region instrumental for better understanding the LOME and Ordovician–Silurian crinoid faunal turnover.

Here we report on a new flexible crinoid, Anticosticrinus natiscotecensis n. gen. n. sp., from the Ordovician–Silurian boundary of Anticosti Island. Phylogenetic analysis of Middle Ordovician–early Silurian flexibles recovers Anticosticrinus natiscotecensis n. gen. n. sp. as a member of family Anisocrinidae. We quantified stratigraphic age uncertainty of A. natiscotecensis using a Bayesian approach for estimating tip-occurrence times in a phylogenetic context. Although results do not provide unequivocal support for the specimen’s precise stratigraphic age, the maximum a posteriori estimate indicates a late Hirnantian age. Regardless of its true age, recognition of Anticosticrinus natiscotecensis provides additional data for evaluating the timing of extinction in flexible crinoids, their diversification and increasing dominance during the Silurian, and crinoid faunal turnover between the Ordovician and Silurian.

UUID: http://zoobank.org/864738dd-3fc9-435b-a83c-e19fd4f6Ad9d

Eocene snakes of India have the potential to shed light on the nature of snake diversification on the subcontinent following the Deccan volcanism at the Cretaceous-Paleogene boundary (K-Pg), when India was still a northward-drifting isolated landmass prior to its collision with Asia. Here, we report a diverse snake fauna from the Eocene of Kutch, western India. The fauna, dominated by aquatic forms, includes palaeophiids, a giant madtsoiid, and a possible nigerophiid. The palaeophiids from the middle Eocene (late Lutetian) comprise ?Palaeophis Owen, 1841 and Pterosphenus rannensis n. sp. Together, these taxa enrich the record of fossil snakes in the poorly known late Lutetian of India and represent the youngest record of Palaeophiidae from the Indian subcontinent. Pterosphenus rannensis n. sp. shows intermediate morphology between Palaeophis and Pterosphenus-grade snakes and is phylogenetically the earliest-diverging member of Pterosphenus Lucas, 1898. Additionally, the middle Eocene Pterosphenus biswasi Rage et al., 2003 is reassessed and retained as a valid taxon based on pterapophyseal morphology and overall form. Biogeographic considerations highlight the importance of the Indian fossil record in understanding the origin and diversification of the genus Pterosphenus. The prevalence of niche partitioning is suggested for the palaeophiids, with Pterosphenus rannensis n. sp. recovered from a tidal setting and ?Palaeophis sp. indet. from a marsh/swamp setting. The new Indian madtsoiid from the middle Eocene (early Lutetian) represents a sympatric taxon with the terrestrial/semiaquatic giant Vasuki indicus Datta and Bajpai, 2024 coexisting in a back-swamp marsh setting. The early Eocene (Ypresian) nigerophiid is among the oldest Cenozoic occurrences of this family globally.

UUID: http://zoobank.org/dc529074-73a6-4869-9b49-44caf9e2d956

The brachyurans Tehuacana tehuacana Stenzel, 1944 and Dromilites americana Rathbun, 1935 have historically been difficult to place in families. A reevaluation of type and referred material from several institutions suggests that the two species are referrable to separate genera in Palaeoxanthopsidae. Hyphalocarcinus new genus is erected to accommodate H. americanus new combination, and Tehuacana remains a distinct genus. Palaeoxanthopsidae evolved and radiated in the Atlantic Ocean, ranging from Late Cretaceous (Maastrichtian) to early Eocene (Ypresian) in age. This work adds to the known diversity of Palaeoxanthopsidae and demonstrates that the family survived and thrived in the Atlantic Ocean in the wake of the end-Cretaceous extinction. Differential preservation of specimens must be evaluated carefully when placing superficially similar taxa at the family, genus, and species level.

UUID: http://zoobank.org/73da26c7-aff7-4abe-8aa5-768944bbf6ee

The late Silurian to Early Devonian floras in the South China Block provide important evidence for the radiation of early land plants, including the well-known Posongchong Formation and Xujiachong Formation of Yunnan Province and the Pingyipu Group of Sichuan Province. However, some taxa in these stratigraphic units are described on the basis of limited specimens, or even a single and/or poorly preserved specimen, and need further investigation. The re-investigation of specimen PB6458 from the Xujiachong Formation at the Xujiachong section near Xujiachong Village, Qujing City, Yunnan Province, which is the holotype of Zosterophyllum spathulatum Li and Cai, 1977, reveals some new characters of its strobilus, sporophylls, and sporangia and denies its assignment to Zosterophyllum Penhallow, 1892. Instead, this specimen should be assigned to Adoketophyton subverticillatum (Li and Cai) Li and Edwards, 1992. This taxonomic revision extends the paleogeographic distribution of Adoketophyton Li and Edwards, 1992 and further enhances this genus as one of the index fossils of Lower Devonian non-marine strata in the South China Block.

A new large dissorophid temnospondyl, Buxierophus pouilloni n. gen. n. sp., is described on the basis of a well-preserved adult skeleton found in the Lower Permian bituminous claystone of Buxières-les-Mines, a fossiliferous locality of the Bourbon-l’Archambault Basin (Allier, France). This new taxon, with a skull length of about 12 cm, is characterized by a unique combination of characters: dorsal midline series of osteoderms composed of two series of thin and unornamented osteoderms, some bearing conspicuous peaks dorsally; internal osteoderms with bi- or multi-lobed dorsal articulation surfaces; neural arches of the same length to that of the osteoderm. A phylogenetic analysis places Buxierophus pouilloni n. gen. n. sp. at the base of the Dissorophidae. This new dissorophid had a semi-aquatic lifestyle. It’s completely ossified ceratobranchial skeleton bears ceratobranchials with grooves as clear indication for its fish-like internal gills in adult stage. It represents the only Lower Permian dissorophid from Europe. Buxierophus n. gen. is part of a rich Permian fauna of the Buxières-les-Mines locality, which is considered as a relatively deep and large paleolake deposit.

UUID: http://zoobank.org/pub/4bc42820-21f6-4674-88ff-eed8597733c3

Macroscopic, modular, morphologically simple skeletons occur in the uppermost Mural Formation (Cambrian, Epoch 2, Bonnia–Olenellus Biozone), west-central Alberta and adjacent east-central British Columbia. They represent organisms that lived almost exclusively in reefal environments dominated by archaeocyaths. Some were attached to archaeocyaths or less commonly other surfaces, and some grew downward, apparently from overhangs or cavities in reefs. Qualitative and quantitative data from a large number of specimens, most of which were serially thin sectioned, indicate that they represent a single, remarkably variable species. The skeletal structure ranges among specimens from entirely cerioid to partially to entirely labyrinthine with irregularly incomplete walls. There is also a wide range of variability in growth form among skeletons, in module size and wall thickness among and within skeletons, in module shape within skeletons, and in number and location of projections extending from the wall into some modules. Module increase occurred by peripheral expansion at the basal surface of the skeleton and longitudinal fission involving projections from the wall as module size increased during vertical growth. Walls of skeletons, now composed of calcite cement, were probably originally aragonite. Modular skeletons from the uppermost Mural Formation are assigned to Rosellatana jamesi Kobluk, 1984a, previously represented only by a few cerioid specimens from correlative strata in the Rosella Formation of north-central British Columbia. The skeletal structure and types of module increase in R. jamesi, and a few similar but less well-known Cambrian taxa from elsewhere in North America, suggest a general biologic affinity with hypercalcified sponges.

Rodney M. Feldmann (1939–2024) had a remarkable scientific career. Publishing primarily in paleontology and geology during seven decades, his legacy includes more than 500 journal articles, conference proceedings, books, book chapters, field guides, and laboratory manuals, in addition to many abstracts of talks presented at conferences. His published work has considerable breadth, but much of it concerns the paleobiology of decapods and other crustaceans. He supervised 47 M.S. theses and 14 Ph.D. dissertations and served in multiple societies and organizations and on editorial boards. Prof. Feldmann was an inspiration to his many students and colleagues around the globe and has left a lasting impact on science.

Three fossil tube fragments from middle Eocene to late Oligocene strata in western Washington State, USA, are here interpreted as those of ancient Ceriantharia (Hexacorallia, Cnidaria). The tube fragments are 3–6 mm in diameter, up to 60 mm long, and the surfaces show an overlapping, fibrous knitted pattern. This surface pattern resembles that of the extant ceriantharid Cerianthus membranaceus. One specimen has numerous benthic foraminiferans associated with, and apparently even embedded in, the tube wall, analogous to some extant Ceriantharia. These fossils likely represent the first fossil Ceriantharia and indicate that their present-day mode of tube construction using ptychocysts was established at latest by the middle Eocene.

According to the International Code of Zoological Nomenclature (ICZN, 1999), the Principle of Homonymy (Article 52) states that when two or more taxa are distinguished from each other, they must not be denoted by the same name because this would cause confusion. Consequently, in a case of homonymy, only the senior name may be used as valid (Art. 52.2). The ICZN (1999) also indicates that if the rejected junior homonym has no known available and potentially valid synonym, it must be replaced by a new substitute name (Art. 60.3), that is, a replacement name.

Funisia dorothea Droser in Droser and Gehling, 2008 is an inferred metazoan-grade tubular organism, endemic to the Ediacara Member, Rawnsley Quartzite, of South Australia (~555–550 Myr), which is characterized by a hollow, elongate body constructed of uniserially repeating modular elements and is one of the most abundantly reported members of the Ediacara biota. Thus, Funisia Droser in Droser and Gehling, 2008 has broad significance for developing understanding of the Ediacara biota and provides a large dataset for testing hypotheses on the biological traits of Ediacaran tubular organisms. This study investigates size changes in Funisia’s modular elements to provide further insight into the paleobiology of this organism through the development of a holistic growth model. Results demonstrate that growth in Funisia was highly regulated to maintain uniform modular element width along the length of an individual and, thereby, an overall cylindrical form despite increasing module width throughout ontogeny. The growth model proposed here is compared with the pre-established growth model for another modular Ediacaran tubular organism, Wutubus annularis Chen et al., 2014, demonstrating that the two taxa had distinct growth patterns and disparate autecological strategies, despite a shared constructional morphology.

Previous typification acts are reviewed herein, in light of the International Code of Zoological Nomenclature, to correct improper procedures while raising new type specimens for Theriosynoecum silvai, Darwinula martinsi and Cypridea araripensis, after loss of the original ones.

This is the first report of Jurassic brachyurans and anomurans from the territory of Russia. These findings come from the Upper Jurassic (Oxfordian) reef limestones of the North Caucasus. The anomuran Gastrosacus wetzleri von Meyer, 1851 was collected from the locality near the Urup River and is the first find of this species outside of western Europe. The dromiacean crab, Goniodromites aliquantulus Schweitzer, Feldmann, and Lazăr, 2007, was discovered from another locality near the Kamennomostsky village. This species was first described from the Oxfordian of Romania. Findings of fossil remains of Goniodromites aliquantulus and Gastrosacus wetzleri from the Oxfordian of the North Caucasus indicate an interconnected paleobiogeographical community of decapod faunas in the Late Jurassic in the Tethys basins.

We describe the findings of cyclidans from the unpublished collection of the famous paleontologist B.I. Chernyshev (1888–1950) in the storage of the Academician F.N. Chernyshev Central Scientific Research Geological Survey Museum (CNIGR museum, St. Petersburg, Russia). These cyclidans were discovered by various researchers in the Carboniferous and Permian of the Urals. They are represented by the following taxa: Oonocarcinus uralicus new species, Uralocyclus feldmanni new species, Ambocyclus capidulum (Chernyshev, 1933), and Magnitocyclus (?) sp. indet. The discovery of the new species Oonocarcinus uralicus n. sp. greatly expands the geographic and stratigraphic interval of the genus Oonocarcinus Gemmellaro, 1890, previously known from the Middle Permian and Triassic. The discovery of Uralocyclus feldmanni n. sp. in the Mississippian deposits of the Chelyabinsk Oblast indicates a wide distribution of the genus Uralocyclus Mychko and Alekseev, 2018 in the Early Carboniferous, because Carboniferous representatives of this genus were previously known only from Ireland and England. The paper provides an up-to-date list of all known cyclidan occurrences and taxa in Russia.

http://zoobank.org/6d69be36-74ca-4205-8eb8-89d1f28458c7

Calyptosuchus wellesi is an aetosaur known from the upper Blue Mesa Member and lowermost Sonsela Member of the Chinle Formation in Arizona, and the Tecovas Formation of the Dockum Group of Texas. The taxon is considered biostratigraphically informative and aids in correlating Upper Triassic strata across the southwestern United States. Our anatomical understanding of Calyptosuchus was primarily based on the holotype specimen from Texas and referred specimens, including several disarticulated elements from the Placerias Quarry in northern Arizona. We provide a re-interpretation of the holotype specimen and describe two new specimens referrable to Calyptosuchus from northern Arizona. Together these specimens provide new information on the cranial anatomy, including dentition, and the positional and intraspecific variation within the carapace and vertebral column of the taxon. This new evidence suggests that the skull anatomy of Calyptosuchus is more similar to that of Neoaetosauroides and Stagonolepis than to other aetosaurs. The dentition of Calyptosuchus supports recent hypotheses suggesting that aetosaurs were more omnivorous/faunivorous. The associated carapace expands our anatomical understanding of characters that vary among trunk paramedian osteoderms. We identify variation in the vertebral column within the trunk region, including the prominence of the centrodiapophyseal lamina and anatomy of the neural spine. Additionally, we report the first documentation of co-ossified sacral vertebrae within Calyptosuchus, which is also the first observation of this state within the Aetosauria outside of the Desmatosuchini. This suggests that co-ossification of the sacral vertebrae may be more prevalent within the Aetosauria than previously recognized.

http://zoobank.org/da3735b8-edf1-465d-820a-316174ed7bf9

Well-preserved specimens of the xanthid crab Lathahypossia aculeata (Busulini, Tessier, and Visentin, 1984) coming from middle Eocene volcanoclastites at Main quarry (Vicenza, Northeast Italy) are housed in three Museums in the Veneto region. Their exoskeletons, mainly chelipeds and thoracic sternum, are significantly encrusted by serpulid tubes assigned to the new species Propomatoceros lathahypossiae. Serpulids belong to the genus Propomatoceros, which has until now ranged from the Triassic to the Cretaceous; this record of the genus is the first in the Cenozoic. The abundance, frequency, and distribution pattern of the serpulid specimens on the different parts of the exoskeleton of the crabs were investigated, shedding light on the ecology/behavior of the encrusting species. Finally, the settlement and growth of serpulids related to sex, size, and molting cycle of the crabs were discussed, hypothesizing on the type of symbiotic relationship among the encrusters and their host.

http://zoobank.org/874be464-8bbf-46dc-8ed7-e7d0112d02b9

Fossil-Lagerstätten, or Lagerstätten, have played a critical role in our understanding of the diversity, abundance, evolution, and systematics of marine arthropods. The tendency toward preservation of Phanerozoic marine arthropods as fossils generally increases as a factor of biomineralization. Concentration deposits (Konzentrat-Lagerstätten) tend to have an abundance of biomineralized arthropod taxa, whereas conservation deposits (Konservat-Lagerstätten) tend to produce a higher biodiversity that includes biomineralizing and non-biomineralizing taxa. Some Lagerstätten incorporate aspects of both concentration and conservation deposits, indicating that these concepts are idealizations, or preservational end members. For arthropod occurrences, it is useful to consider another dimension of Lagerstätten: their taphonomic associations. This leads to a more nuanced understanding of arthropod fossilization history. Four taphonomic associations account for a substantial number of marine arthropod occurrences: (1) concretions, (2) clusters, (3) event beds, and (4) microbially sealed sediments. Each of these occurrences can blur the distinctions between, or the means of recognizing, the idealized genetic categories of concentration deposits and conservation deposits.

The hitherto oldest known mass mortality of clam shrimp is described from the Early Devonian (Emsian) of Luxembourg. This (almost) monospecific clam shrimp association allows for a much more comprehensive assessment and understanding of preservational and ontogenetic variation in a single taxon, Pseudestheria diensti (Gross, 1934). This suggests that other taxa originally described from the “classical” Willwerath locality, the type locality of P. diensti, are variants of the latter, and thus Pseudestheria subcircularis Raymond, 1946 and Palaeolimnadiopsis ? eifelensis Raymond, 1946 are synonymized here with P. diensti. A further clam shrimp taxon, for which we propose a new species, Palaeolimnadia stevenbeckeri n. sp., is found in the same stratum, but not in the mass mortality layer itself. The clam shrimp mass mortality is interpreted to reflect sudden destruction of the original habitat on a delta plain and subsequent transport and burial in a marginal marine low-energy setting.

http://zoobank.org/0cfcb6a1-3fb7-4a1a-a1a4-609f8b1bc536