A century and a half of paleoneurological study of synapsids has provided invaluable insight into the evolution of their brain, sense organs, behavior, and physiology. Here, we review and discuss the evidence for parental care, brooding, intraspecific combat, display, and gregariousness, and conclude that evidence for higher levels of social interactions and communication is piling up and may soon push the origin of sociality in the mammalian lineage to the middle Permian. We also review the paleoneurological cues (the trigeminal canals, parietal foramen, and inner ear) that support a new evolutionary hypothesis in which the homeogene MSX2 mutated early in the probainognathian cynodonts and changed their biology towards a more mammalian condition. This includes the loss of the parietal foramen, inflation of the cerebellar vermis, maintenance of a fur pelt, and appearance of mammary glands, some 247 million years ago. This was followed by the origin of the ability to whisk 241 million years ago, and that of endothermy 233 million years ago, as indicated by the evolution of the trigeminal and semicircular canals, respectively. Finally, we review the immense progress made in the study of encephalization and support that probainognathians went through a neurosensory revolution during the Triassic. Their newly acquired small body size, fur, and nocturnal lifestyle generated sensory input that affected the evolution of all their sensory organs, leading up to the development of the modern mammalian brain.

The Caribbean islands represent some of the most biologically diverse places on Earth, but much of that diversity is now at risk due to human impact. Larger islands in the Caribbean host more native species, but small islands still hold together a significant portion of the regional biota. Although our knowledge of extinct and extirpated taxa continues to improve, there are hundreds of islands, each with their own unique faunal histories from where there is little information about their ancient diversity. Sombrero is a very small island (0.38 km2) located within the limits between the Greater and Lesser Antilles and is largely barren of vegetation and freshwater. The island was extensively mined for bird guano in the 1800s, which profoundly altered its topography and fauna. Here, we describe a collection of microvertebrates recovered in 1964 from Sombrero, which documents an unexpectedly high number of colonization events and high extinction rate for this territory. The late Quaternary deposits from the island contain remains of five types of lizards, a snake, a tortoise, and an anuran that colonized the island once it became aerially exposed in the early Pleistocene. The ability for such a small, remote island to have eight colonizing taxa in < 2.5 Ma, provides support for the role that island hopping played in regional biodiversity in the Cenozoic (e.g., GAARlandia), even across small, barren islands. Furthermore, these fossils further show that large scale defaunation also affected vertebrate communities on very small islands in the Caribbean.

Biformites insolitus Linck, 1949 and very shallow, partially facetted, vertical burrows occur together in calcareous siltstone as convex hypichnia of sandstone on bedding soles within the Lower Devonian Clam Bank Formation, western Newfoundland. The ichnofossils occur within thinly interstratified siltstone and sandstone that accumulated within a physically stressed, euryhaline, peritidal paleoenvironment. B insolitus consists of straight to sinuous, narrow (2–3 mm), strap-like imprints commonly up to 7 cm long that display a medial axial depression and paired (opposite) conical (rounded blunt tipped) to irregular blocky and rectangular-shaped protuberances. These structures are interpreted to represent the impressions of ophiuroid arms, including representations of tube feet and ambulacral skeletal structure. Ornamentation detail appears proportional to the depth of an imprint and is a measure of the amount of downward force of an arm relative to horizontal motion. Apparent branching of imprints represents arm overprints. Incompletely facetted transverse sections of burrows, also filled with sandstone, warrant comparison with the ichnogenus Pentichnus, but incomplete preservation of a possible higher-order symmetry defers ichnotaxonomic designation. The imprints are very shallow (<1 cm) and fit with very near-surface burrowing as observed among some modern ophiuroids. The burrows are either a variant of Pentichnus, thereby expanding its current stratigraphic range, or broaden a unique ichnotaxobase of facetted burrows. A middle Paleozoic record of B. insolitus narrows the current disparity with the post-Cambrian ophiuroid skeletal record. Its spatial association with burrows in a peritidal paleoenvironment reinforces the complex behavior of ophiuroids, their ecological breadth, and opportunistic behavior.

Anapachydiscus (Anapachydiscus) haegerti n. sp., an ammonite belonging to the Pachydiscidae, is reported for the first time from the upper Campanian Northumberland Formation of Hornby Island, British Columbia. Thirty-five specimens have allowed for the complete ontogenetic reconstruction of the taxon as well as thanatocoenosic (death assemblage) observations with paleoecological implications for ammonoid early life. Although isolated juvenile specimens occur, instances of concretions containing a multitude of individuals are typical. One concretion yielding twenty-six early-stage juveniles lends support to a mode of preservation reflective of life association through a taphonomic process of capture and burial. The new species presents age-diagnostic utility as a distinct fossil within the molluscan assemblage of the Nostoceras (Didymoceras?) adrotans regional subzone; a highly constrained interval of the upper Campanian in the eastern North Pacific. A specimen attributed to Anapachydiscus (Anapachydiscus) cf. A. (A.) fascicostatus from the upper Campanian of the Cedar District Formation on Denman Island is also described, and the genus Anapachydiscus is retained with an emended diagnosis. Additional collections have enabled revised conceptualizations of Pachydiscus (Pachydiscus) hornbyense and Pachydiscus (Pachydiscus) ootacodensis accounting for the spectrum of variance within these species. Recognition of an upper Campanian P. (P.) ootacodensis–Pachydiscus (Pachydiscus) suciaensis Concurrent-range Zone is proposed for the eastern North Pacific to assist broader efforts of interregional biostratigraphic correlation given the endemic limitation of the latter taxon.

UUID: http://zoobank.org/d8eb27f6-7221-4efb-9548-ec2001986b19

Malacostracan crustaceans are very diverse today, but their evolutionary history and biodiversity during the Paleozoic remain understudied. One clade within Malacostraca is Belotelsonidea, crustaceans with a shrimp-like body plan only known from the Carboniferous. We describe the fourth species of this group, Lobetelson feldmanni n. sp., from the Pennsylvanian (Kasimovian) of the Kinney Brick Quarry, New Mexico, USA. The holotype is a flattened, relatively complete specimen with an eye preserved. A second, less well-preserved specimen from the same locality might be referable to the new species. This record represents the youngest record of Belotelsonidea, now ranging from the upper Tournaisian to the Kasimovian, equivalent to ca. 40 Myr. Paleobiogeographically, belotelsonids are only known from Scotland and various parts of the USA thus far, located near the equator to ~20° south during the Carboniferous. Whereas most belotelsonids are thought to have lived in a marine environment, some of the oldest specimens from Scotland are interpreted to have inhabited areas with limited to no marine influence.

UUID: https://zoobank.org/6c52b87d-9259-4b19-85c7-71b425bb6187

Squamate faunas from the lower Eocene of Europe are rare. We here describe pleurodontan iguanian (potentially Geiseltaliellus Kuhn, 1944), scincoid, and Squamata indet. jaw remains from Cos locality (near the Caylus village, southwestern France). The age of the Cos deposit has been proposed to fit the MP 10−11 interval (MP 10b; late Ypresian). Thus, it either corresponds to the end of the Early Eocene Climatic Optimum (EECO) or slightly postdates it. Although very fragmentary, the finds represent the first evidence of these clades in this locality, which is one of the oldest from Phosphorites du Quercy, adding to the squamate paleobiodiversity of the site. Besides iguanians and scincoids, the fauna also includes gekkotans, glyptosaurids, varanoids, and a constrictor snake. Some of the genera from Cos are known solely from this locality, revealing a crucial part of the squamate history in Europe. In the last few years, our knowledge of the Paleocene and especially early Eocene lizard faunas has increased. This allows a better understanding of the faunas and their changes due to temperature changes and migrations. Records are still very sketchy at European localities, but the overall picture is somewhat clearer, even on a smaller scale. A small but visible drop in lizard diversity appears to be present at localities from MP 8−9 relative to those from MP 7, whereas at MP 10, the diversity slightly increased. This appears to correlate well with observed changes in temperature.

A new species of syngnathiform fish, Gerpegezhus daniaoriundus n. sp., from the Eocene Fur Formation of Denmark is described herein. The description is based on 17 specimens preserved in either soft diatomite or carbonate concretions. The two lithologies result in different preservation of the morphological features. Gerpegezhus daniaoriundus n. sp. exhibits a set of diagnostic features of the extinct monotypic family Gerpegezhidae and of the genus Gerpegezhus, including (1) greatly elongated body, (2) presence of ossified myoseptal tendons, (3) lower procurrent caudal-fin rays absent, (4) dorsal- and anal-fin spines absent, and (5) pelvic fin and girdle absent. It can be separated from the species Gerpegezhus paviai by having a much slenderer body bearing unpaired leaf-like appendages protruding from its ventral side, and completely different meristic values, including up to 39 (or 40) vertebrae, a total of 16 unbranched caudal-fin rays, dorsal and anal fins with 5 and 16 unbranched rays, respectively, and a different organization of body armor comprising two dorsal bilateral series of dermal plates. The occurrence of the genus Gerpegezhus from the Fur Formation provides a remarkable example of the biogeographic relationships between the North Sea realm and the Tethys in the earliest Eocene.

http://zoobank.org/3a57ae6b-faae-44c6-9a0a-aaeea03b57b3

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.