In this study, middle to late Mississippian microfossil assemblages from the Maritimes Basin of eastern Canada (Nova Scotia, SW Newfoundland, and New Brunswick) are closely compared to those from Western Paleotethys basins. The comparison is focused mainly on foraminifers and calcareous algae. Most foraminifers and algae described from the Maritimes Basin are considered cosmopolitan, and the occurrence in western Europe and northern Africa of taxa previously considered endemic to the North America Realm suggests a close paleobiogeographic relationship. This European/African correlation is further supported by other foraminiferal/algal taxa, the importance of which were previously overlooked, including: Plectogyranopsis ex gr. P. hirosei (Okimura, 1965), MikhailovellaGanelina, 1956, Koktjubina windsorensis (Mamet, 1970), Polysphaerinella bullaMamet, 1973, Mstinia Dain in Dain and Grozdilova, 1953, HaplophragminaReitlinger, 1950, OmphalotisShlykova, 1969, PseudolituotubaVdovenko, 1971, PseudoendothyraMikhailov, 1939, Saccamminopsis (Sollas, 1921) Vachard and Cózar, 2003, KamaenellaMamet and Roux, 1974, and AnthracoporellopsisMaslov, 1956. Some species recorded in the Maritimes Basin have been typically recorded in Britain and Ireland in the southern platform of Laurussia. This implies a connection via the Rhenohercynian Ocean, whereas statistical analyses suggest that Maritimes Basin assemblages are closer to those of the Gondwana platform, which could have been established via the Paleotethys Ocean, and also with terranes northwest of the Variscan Front, in which its most logical connection should be with a still-open Rheic Ocean during the Visean and early Serpukhovian. Those taxa demonstrate a more-or-less continuous faunal and microfloral interchange between the Maritimes Basin and the Western Paleotethys paleobiogeographic realm. Furthermore, the width of the Paleotethys and Rheic oceans separating these regions is not considered excessive, particularly during the late Visean and early Serpukhovian.

Cretaceous carbonates in the Geyik Dağı area (Central Taurides, southern Turkey) are represented by two successions with different paleoenvironmental settings: open shelf to slope succession of Cenomanian to Danian age and inner platform succession of Albian to Maastrichtian age, which is interrupted by a post-Cenomanian disconformity. Outcropped lowermost part of the platform-type one is composed of rudistid limestones corresponding to the Urgonian-type carbonates and belongs to the Geyik Dağı Unit (=Anamas-Akseki Carbonate Platform). It contains a rich assemblage of larger benthic foraminifera including orbitolinid, chrysalidinid, cuneolinid, nezzazatid, and miliolid taxa, which has been illustrated and documented here for the first time from the upper Albian of the Tauride Carbonate Platform. The occurrence of such a diversified foraminiferal fauna indicates a prominent high diversity that took place in the Tauride Carbonate Platform during the late Albian time, which corresponds to a major emersion period in some parts of the platform.

This is the first of two comprehensive taxonomic works on the early Miocene (ca. 23–20 Ma) bryozoan fauna associated with coral reefs from the Siamaná Formation, in the remote region of Cocinetas Basin in the La Guajira Peninsula, northern Colombia, southern Caribbean. Fifteen bryozoan species in 11 families are described, comprising two cyclostomes and 13 cheilostomes. Two cheilostome genera and seven species are new: Antropora guajirensis n. sp., Calpensia caribensis n. sp., Atoichos magnus n. gen. n. sp., Gymnophorella hadra n. gen. n. sp., Cribrilaria multicostata n. sp., Cribrilaria nixor n. sp., and Figularia bragai n. sp. Eight species are identified only at genus level and remain in open nomenclature. Of the species found, 27% have erect colonies and 73% encrusting colonies. Both types contributed to the reef framework and produced sediment. The observed bryozoan diversity was higher in the barrier reefs than in the lagoonal patch reefs.

New linguliform microbrachiopods from the Middle Ordovician are described and illustrated. This fauna was recovered from the uppermost beds of the San Juan Formation in two sections of the Central Precordillera (Argentina), which are accurately dated to the Lenodus pseudoplanus Zone (middle Darriwilian). The fauna consists of the obolid Luthieria diminuta n. gen. n. sp., and the acrotretids Eoconulus tucunucoensis n. sp., Conotreta andina Lavié, Serra, and Feltes, Scaphelasma zharykensis Popov, and Numericoma rowelli Holmer et al. This low-diversity lingulate association displays close similarities with coeval faunas that inhabited the Laurentia, Baltica, and Kazakhstanian regions, in agreement with evidence from other linguliform and rhynchonelliform brachiopods.

Devonian orthotetides from South America have often been uncritically assigned to a limited number of broadly described species. Schellwienella clarkei n. sp. is described from the Ponta Grossa Formation, Paraná Basin, southern Brazil. These brachiopods had been identified as Schuchertella agassizi. Schellwienella clarkei n. sp. differs from Schuchertella agassizi on the basis of shell structure, dental plates, and cardinalia.

Paleozoic scaphopods are among the most poorly known mollusks because of their featureless tubular shell morphology and fragmentary preservation. An apical orifice at the posterior end of a conch is a diagnostic character of Scaphopoda that distinguishes them from other groups of animals that produce similar calcareous tubes, but this structure is rarely preserved. A rich molluscan fauna from the Permian Akasaka Limestone in central Japan includes scaphopod shells, and past studies have reported four species, all of which were based on fragmentary specimens. This study recognizes six species in the Akasaka Limestone mainly on the basis of museum/institution collections, and a new genus (Minodentalium) and three species (Prodentalium onoi, M. hayasakai, and M. okumurai) are described, two known species (P. akasakensis and P. neornatum) are redescribed in more detail, and one species (Prodentalium sp.) is described under open nomenclature. The following eight known species are allocated to the new genus Minodentalium: Plagioglypta furcataWaterhouse, 1980; Pl. girtyiKnight, 1940; Pl. subannulataEaston, 1962; Dentalium ingensDe Koninck, 1843; D. meekianumGeinitz, 1866; Pl. prosseriMorningstar, 1922; Dentalium priscum Münster in Goldfuss, 1842; and D. herculeum De Koninck, 1863. All the species, except for M. hayasakai, are gigantic, reaching 200 mm or more in length. The species richness is the greatest known from a single locality/formation worldwide.

Although taxonomically distinct, the Cenozoic pleurotomariids are the bottlenecked remnants of the Mesozoic members of the family in terms of morphology, with only conical forms surviving the end-Cretaceous mass extinction. Here, we propose an updated classification scheme for the Cenozoic representatives of this group, based on data from the entire Cenozoic pleurotomariid fossil record. We consider all conventional as well as several new characters so that this scheme can readily help to distinguish Cenozoic pleurotomariid genera. Following the new classification scheme, a revision of the generic status of Cenozoic species previously assigned to ‘Pleurotomaria’ Defrance, 1826 is presented.

Only a few Cenozoic pleurotomariid gastropods have been reported from the Indian subcontinent. Here we report four species from the Oligocene of the Kutch Basin and the early Miocene (Burdigalian) of the Dwarka Basin of Gujarat, western India, of which two are described as new: Perotrochus bermotiensis n. sp., Entemnotrochus kathiawarensis n. sp., Entemnotrochus cf. E. bianconii, and Entemnotrochus? sp. 1.

Abundant articulated specimens of the oryctocarine trilobite Oryctocarella duyunensis from the lower Cambrian (Stage 4, Series 2) Balang Formation at the Bulin section in western Hunan Province, South China, permit the description of all meraspid degrees. The maximum number of thoracic segments observed in this collection is 11. Meraspid growth was accompanied by progressive and gradual change in overall form, and this animal showed an homonymously segmented trunk with variation in the number of pygidial segments during ontogeny. Such variation permits a variety of plausible explanations, but a model of successive instars defined by the number of thoracic segments, and in suborder by the number of pygidial segments, is highly unlikely to explain the growth pattern because it would result in the loss of trunk segments between some instars. Degree-based ontogenetic staging is compatible with the variation observed.

The Mesozoic mecopteran family Mesopsychidae has attracted extensive attention by their long proboscis that is presumably associated with pollination of early gymnosperms. Three previously reported species of Lichnomesopsyche Ren, Labandeira, and Shih, 2010 from the Middle–Upper Jurassic Haifanggou Formation at Daohugou (Inner Mongolia, northeastern China) display distinct resemblances in wing venation, so that their classification, based on currently described characters, remains elusive. Herein, we describe and figure exquisitely preserved male genital structures of L. gloriae Ren, Labandeira, and Shih, 2010, L. daohugouensis Ren, Labandeira, and Shih, 2010, and L. prochoristaLin et al., 2016, which can be used for defining and recognizing the three species. Our discovery indicates that the male genitalia are the major critical structures for species-level classification of the peculiar genus Lichnomesopsyche. Details of the maxillary palps and legs of L. gloriae and L. daohugouensis are also described.

Restudy of Proexenocrinus inyoensisStrimple and McGinnis, 1972, shows that this earliest-known rhodocrinitid diplobathrid camerate crinoid (late Floian, Early Ordovician) expresses the only known record of ambulacral floor plates within pinnules. These pinnule floor plates are remarkably conserved plesiomorphic expressions, with anatomy similar to floor plates of some of the earliest pentaradiate echinoderms, although on a smaller scale. Proexenocrinus floor plates provide direct skeletal evidence that the general resemblance of blastozoan (eocrinoid, diploporan, rhombiferan) brachioles and crinoid pinnules is the product of homoplasy. Proexenocrinus posterior cup morphology is interpreted to include an anitaxis, a distinctive posterior interray morphology.

Upper Ordovician strata exposed from the Baiyanhuashan section is the most representative Late Ordovician unit in the northwestern margin of the North China Craton (NCC). In total, 1,215 conodont specimens were obtained from 24 samples through the Wulanhudong and Baiyanhuashan formations at the Baiyanhuashan section. Thirty-six species belonging to 17 genera, including Tasmanognathus coronatus new species, are present. Based on this material, three conodont biozones—the Belodina confluens Biozone, the Yaoxianognathus neimengguensis Biozone, and the Yaoxianognathus yaoxianensis Biozone—have been documented, suggesting that the Baiyanhuashan conodont fauna has a stratigraphic range spanning the early to middle Katian. The Baiyanhuashan conodont fauna includes species both endemic to North China and widespread in tropical zones, allowing a reassessment of the previous correlations of the Katian conodont zonal successions proposed for North China with those established for shallow-water carbonate platforms at low latitudes.

Herbivory is a common ecological function among extant lepidosaurs, but little is known about the origin of this feeding strategy within Lepidosauria. Here we describe a sphenodontian (Lepidosauria) from the Late Triassic of western North America, Trullidens purgatorii n. gen. n. sp., that reveals new aspects of the earliest radiation of herbivorous lepidosaurs. This taxon is represented by an isolated lower jaw with robust structure bearing transversely widened dentition and extensive wear facets, suggesting a masticatory apparatus specialized for herbivory. An unusual ‘incisor-like’ tooth is present at the anterior end of the jaw; a unique feature among lepidosaurs, this tooth is convergent with the incisors of extant rodents and lagomorphs. Phylogenetic analyses support the placement of this taxon within opisthodontian sphenodontians, a group sharing derived cranio-dental morphologies specialized for herbivory. The new taxon was recovered in a recently discovered and unnamed series of Upper Triassic strata in southeastern Colorado, USA, exposed in Canyons incised by the Purgatoire River and its tributaries. These strata comprise a dominantly red-bed sequence of conglomerates, sandstones, and siltstones deposited in a fluvio-lacustrine setting, preserving a Late Triassic biota of invertebrate and vertebrate ichnofossils, plant macrofossils, bony fish, temnospondyl amphibians, and reptiles. We use aetosaur osteoderms as biostratigraphic links to the nearby Chinle Formation of Arizona, USA, establishing a middle Norian age for these strata. The presence of an opisthodontian from western equatorial Pangaea in the Norian Stage reveals a near-global radiation of this clade across the Pangaean supercontinent during the Late Triassic.

Traversodontidae is a group of Triassic herbivorous/omnivorous cynodonts that represents the most diversified lineage within Cynognathia. In southern Brazil, a rich fossil record of late Middle/mid-Late Triassic cynodonts has been documented, with Exaeretodon riograndensis Abdala, Barberena, and Dornelles, 2002 and Siriusgnathus niemeyerorumPavanatto et al., 2018 representing two abundant and well-documented traversodontids. The present study provides a comparative analysis of the morphology of the nasal cavity, nasal recesses, nasolacrimal duct, and maxillary canals of both species using computed tomography, highlighting the changes that occurred in parallel to the origin of mammaliaforms. Our results show that there were no ossified turbinals or a cribriform plate delimiting the posterior end of the nasal cavity, suggesting these structures were probably cartilaginous as in nonmammaliaform cynodonts. Both species show lateral ridges on the internal surface of the roof of the nasal cavity, but the median ridge for the attachment of a nasal septum is absent. Exaeretodon riograndensis and S. niemeyerorum show recesses on the dorsal region of the nasal cavity, which increase the volume of the nasal cavity, potentially enhancing the olfactory chamber and contributing to the sense of smell. On the lateral sides of the nasal cavity, the analyzed taxa show a well-developed maxillary recess. Although E. riograndensis and S. niemeyerorum have roughly similar nasal cavities, in the former taxon, the space between the left and right dorsal recesses of the nasal cavity is uniform along its entire extension, whereas this space narrows posteriorly in S. niemeyerorum. Finally, the nasolacrimal duct of S. niemeyerorum is more inclined anteroposteriorly than in E. riograndensis.

Studies focused on deciduous dentition, ontogenetic series, and tooth eruption and replacement patterns in fossil mammals have lately increased due to the recognized taxonomic and phylogenetic weight of these aspects. A study of the deciduous and permanent dentition of Interatherium and Protypotherium (Interatheriinae) is presented, based mainly on unpublished materials. Deciduous cheek teeth are brachydont and placed covering the apex of the respective permanent tooth; in addition, some morphological and metrical differences are observed along the crown height. Five dental ontogenetic stages are distinguished among the juvenile specimens on the basis of the degree of wear, the replacement of the deciduous premolars, and the eruption of the molars. The crown height and the wear degree of different Interatheriinae taxa show: (1) eruption pattern of molars in an anterior–posterior direction (M/m1 to M/m3); (2) pattern of replacement of deciduous premolars and eruption of permanent premolars in a posterior–anterior direction (dP/dp4 to dP/dp2 and P/p4 to P/p2); and (3) eruption of M/m3 before the replacement of dP/dp4. Results allow evaluating the diagnostic dental characteristics used to describe some interatheriines, as well as reinterpreting some taxonomic assumptions: the holotype of Protypotherium diversidens Ameghino, 1891 is recognized as a juvenile of another species of the genus, and the species is not validated, considering it as Protypotherium sp.; the holotype of Eudiastatus lingulatus Ameghino, 1891 falls in the variability of Protypotherium, becoming P. lingulatus new combination, tentatively maintaining the species and implying the synonymy between Eudiastatus and Protypotherium; and the holotype of Eopachyrucos ranchoverdensisReguero, Ubilla, and Perea, 2003 is reinterpreted as bearing deciduous premolars.