The phylum Bryozoa had long been the only major phylum unknown from the Cambrian and by inference the Cambrian Explosion of biodiversity. When described in 2010 as a late Cambrian cryptostome bryozoan, Pywackia baileyi Landing in Landing et al., 2010 became the oldest known bryozoan (early Cambrian bryozoans have since been described). Controversy remains about the phylum-level identification of Pywackia Landing in Landing et al., 2010—one study proposed an interpretation of Pywackia as an octocoral. No previous studies of the skeletal microstructure of Pywackia have employed the analysis of petrographic thin sections and high-magnification scanning electron microscopy. These two methods, with the addition of data from previous studies, are employed in this analysis of skeletal microstructure, a feature often important for higher-level taxonomic identification. Although many candidate groups were considered, Pywackia's distinctive pillar and laminae, porous skeleton like many Cnidaria, topology of the body walls, and growth of modules are consistent with a cnidarian affinity. Pywackia skeletons with primary microstructure were 100% phosphate mineral and were collected from a setting of pervasive phosphatic replacement, which leaves uncertainty as to the original skeletal composition. Pywackia is not assigned here to a cnidarian class and likely represents an early, rare, short-lived cnidarian evolutionary group.

This study provides the first focused investigation of rudist bivalves from the Upper Cretaceous of the Gulf Coastal Plain (GCP) in the southern US and previously undescribed specimens from the Flor de Alba Limestone Member of the Pozas Formation in Puerto Rico. Identified rudists from the GCP comprise the Monopleuridae, including Gyropleura, as well as Radiolitidae, including Biradiolites cardenasensi, Durania maxima, Guanacastea jamaicensis, Radiolites acutocostata, and Sauvagesia. Integrating rudist occurrences within well-established GCP biostratigraphy allows for extension of upper ranges of D. maxima and R. acutocostata into the late Campanian, and extension of the lower ranges of B. cardenasensis and G. jamaicensis into the early Campanian. Identified rudists from Puerto Rico comprise the Hippuritidae and include Barrettia monilifera, which supports the age of the Flor de Alba Limestone Member of the Pozas Formation as middle Campanian. Combined taxonomic, biostratigraphic, and paleobiogeographic analyses indicate there is no rudist fauna endemic to the GCP, and the region marks the northeastern range of the Caribbean genera Biradiolites, Durania, Guanacastea, Gyropleura, Radiolites, and Sauvagesia during the Campanian and Maastrichtian. The new occurrences help inform future updates of Late Cretaceous sea surface-current reconstructions for the Caribbean and Western Interior Seaway, USA.

Seven species of cornulitids, one unidentified tubicolous shell, and the problematic bryozoan Lagenosypho Spandel, 1898 are here described from the Katian of Baltica. Three new species—Cornulites lindae new species, Cornulites meidlai new species, and Conchicolites kroegeri new species—are described. The unidentified tubicolous organism has punctate shell structure and setae-like structures that can best be affiliated with lophophorates. The Hirmuse fauna indicates that the diversity and number of cornulitids in the Ordovician of Baltica has been underestimated and it is likely that the Baltic cornulitid fauna was as diverse and abundant as the fauna of Laurentia. Clay mud-bottom environments supported the highest cornulitid diversity in the Late Ordovician of Baltica. The occurrence of intermediate forms indicates that some tentaculitid characters, e.g., regular annulation and a nearly straight shell, which were thought to be apomorphies of free-living tentaculitids, were actually inherited from ancestral cornulitids. The cornulitid fauna of the Late Ordovician of Laurentia somewhat resembles the cornulitid fauna of the Late Ordovician of Baltica, but there are fewer common faunal elements between Gondwana and Baltica.

UUID: http://zoobank.org/cc704237-b578-4d06-a8ed-8457ca3ce972

The Jurassic trigoniid bivalves of Gebel Maghara, northern Sinai, Egypt are described and figured. They belong to 14 species, nine genera, and two families. The identified taxa occur in rocks ranging in age from the Toarcian (Lower Jurassic) to the lower Kimmeridgian (Upper Jurassic). Five genera and one species are new: Magharitrigonia asymmetrica new genus new species; Cotswoldella aff. C. hemisphaerica (Lycett, 1853); Cornbrashella pullus (J. de C. Sowerby, 1826); Parorthotrigonia lepidomorpha (Abdallah and Fahmy, 1969); and Retetrigonia imbricata (J. de C. Sowerby, 1826). Five species, Trigonia reticulata Agassiz, 1840, T. cf. T. castor d'Orbigny, 1849, Promyophorella tuberculata (Agassiz, 1840), Orthotrigonia exortiva (Kitchin, 1903), and O. gracilis (Kitchin, 1903) are recorded from the Jurassic rocks of Gebel Maghara for the first time.

UUID: http://zoobank.org/4dc3cc67-6bc3-406f-a022-6a05ed97efc6

Fossil capitate hydrozoans require exceptional conditions for preservation. Here we describe Bertratis ciurcae new genus, new species from the Silurian (Pridoli) of southern Ontario and upper New York State, where it occurs in association with a diverse assemblage of eurypterids. Only the float (pneumatophore) is well preserved, surviving as a thick carbonaceous compression. The new taxon is the largest fossil capitate reported, reaching a width of 17 cm, and the third Porpita-like example known from the Paleozoic. It was a rare pelagic component of the biota of the well-known Bertie Group Lagerstätten.

UUID: http://zoobank.org/1eb789e3-67b4-4e46-9baf-6320d4b67d6c

All genera based on fossil type species belonging to the family Mactridae are alphabetically listed in this work. The oldest records of the Mactridae come from Cretaceous deposits of North America. However, this group of bivalves has been worldwide recorded from the Paleogene and Neogene. An emended diagnosis for each genus is herein provided. In addition to that, type species, type localities, and occurrences are included. For each genus, a remarks section includes the most recent published taxonomic opinions. Nevertheless, in some cases, new taxonomic decisions based on morphological analysis of types have been taken. Genera based on extant type species are excluded from this work. Forty-five genera are listed herein and type material has been reproduced wherever possible. Ionesimactra nom. nov. is proposed as a replacement name for Caspimactra Ionesi (non Caspimactra Ali-Zade and Kabakova). This work constitutes the basis for future revisions related to fossil taxa of the family Mactridae from different regions.

UUID: https://zoobank.org/ccc72130-4ea2-44a9-add9-51cfce58f2d5

A diverse molluscan assemblage dominated by turritellid gastropods found in Kachchh, western India, has been interpreted in the past as Late Jurassic (Oxfordian) in age, based on associated undoubtedly Oxfordian ammonites. Recently, several investigations focused on the assemblage dealing with taxonomic, paleoecological, and evolutionary aspects. An analysis of the associated bivalve fauna, foraminiferal assemblage, and the geological context strongly suggests a Miocene rather than a Jurassic age and invalidates several conclusions drawn from the alleged Jurassic age of the fossils.

The diplobathrid camerate crinoid genus Monstrocrinus is morphologically reinterpreted on the basis of new finds from the upper Emsian (Lower Devonian) to lower Eifelian (Middle Devonian) of Germany (Rhenish Slate Mountains, North Rhine-Westphalia, and Rhineland-Palatinate). The most complete, new specimen has a long segment of column projecting outward from the basal concavity, which confirms that the Monstrocrinus crown was attached to a column as an adult. Thus, a free-living life mode of a passively rolling or drifting crinoid is refuted and Monstrocrinus is reinterpreted as an attached, stalked echinoderm. This finding is supported by re-examination of the historical type material. A column attachment with a central pentalobate axial canal was recognized for the first time in the calyx of the holotype of the type species Monstrocrinus securifer. The holotype of Monstrocrinus granosus is far more complete than previously thought. It is a partially disarticulated crown embedded together with an associated longer part of the column. The extraordinary spines on the calyx plates of Monstrocrinus can be divided into eight morphological types and into two superordinate categories: “Category A” is a physical part of the calyx plate, whereas “Category B” is an attachment onto the calyx plate. Taxonomically, M. aliformis from the upper Emsian of Spain is treated herein as a subjective junior synonym of M. securifer.

Anticosti Island, eastern Canada, records an exceptionally thick and well-exposed Ordovician/Silurian boundary section that hosts a series of diverse marine invertebrate faunas across the Late Ordovician mass extinction. However, the base of the terminal Ordovician stage, the Hirnantian, has been difficult to identify on Anticosti due to the lack of a traditional Hirnantia fauna within the Upper Ordovician Ellis Bay Formation. Previously, the eponymous taxon of the Hirnantia fauna, and type species of the genus Hirnantia, H. sagittifera (M'Coy, 1851) has been reported only from the uppermost Ellis Bay Formation, leading to uncertainty as to the age of the lower Ellis Bay Formation. Here we report Hirnantia notiskuani n. sp. from the lowermost Ellis Bay Formation. This new species is similar to the type species, H. sagittifera, but is distinguished by its strongly dorsibiconvex shell in mature forms and variously developed uniplicate anterior commissure. Occurrences of these two similar species of Hirnantia, H. notiskuani and H. sagittifera, within the lower and uppermost Ellis Bay Formation, respectively, indicate a Hirnantian age for the entire Ellis Bay Formation, a finding that is supported by recent palynological and chemostratigraphic studies. Brachiopod assemblages within the Ellis Bay Formation therefore are best characterized as a unique and diverse Hirnantia fauna, consisting of genera from both the typical Hirnantia fauna and the epeiric seas of Laurentia.

UUID: http://zoobank.org/1c1dff6a-ee38-4cd3-b8bd-3d803a2774ef

The present contribution illustrates the type material of the Lower Cretaceous ammonoids Ptychoceras aequicostatus Gabb, 1864 (type species of Helicancylus Gabb, 1869) and Hamiticeras pilsbryi Anderson, 1938 (type species of Hamiticeras Anderson, 1938). The typification and taxonomic validity of both genera are clarified, and the affinities with coeval Acrioceratidae are discussed. Their stratigraphic range is investigated with implications for correlation between northern Pacific and European ammonoid scales.

The western Mongolian Lake Zone was a Neoproterozoic to early Paleozoic volcanic arc where tuffs, lavas, fossiliferous siliciclastics, and carbonates accumulated during the early Cambrian. An uppermost Cambrian Series 2 (upper Stage 4) trilobite assemblage is described here from the Burgasutay Formation representing a continuous lower Cambrian succession at the Seer Ridge of the Great Lake Depression. The new assemblage is dominated by dorypygids and consists of 13 trilobite genera belonging to nine families including Catinouyia heyunensis new species. These fossils comprise the youngest and richest lower Cambrian trilobite assemblage in Mongolia. The composition of the Lake Zone fauna suggests its biogeographic affinity with the Siberian Platform and Altay-Sayan Foldbelt, but the presence of inouyiids also implies a connection of this region with East Gondwana.

UUID: http://zoobank.org/fb0ebe23-144f-46ed-9543-7df9eea85fbc

Acteonellids were one of the most significant groups of marine macro-invertebrates in the Late Cretaceous biota of the Tethyan Realm. They were common faunal elements associated with Cretaceous carbonate platform communities most notable for their abundance of rudist frameworks and thrived in coeval lagoons. The Upper Cretaceous fossil-bearing Karababa Formation, cropping out in southeastern Turkey, yields a remarkable assemblage of acteonellid gastropods and rudists. Cretaceous gastropods from sedimentary successions in Turkey barely have been studied over the past 80 years. The subgenus Trochactaeon, a very successful and widespread taxon of heterobranch gastropods within the family Acteonellidae, dominated acteonellid assemblages throughout the Late Cretaceous. In the present work, we present the first record of Trochactaeon (Trochactaeon) giganteus subglobosus from Turkey. It is from a single lower Campanian bed in the upper part of the Karababa Formation of the Gölbaşı region (south of Adıyaman), corresponding to the northwestern part of the Arabian Platform. This record complements information on the temporal and spatial distribution of Trochactaeon at the southern margin of the Tethyan Ocean during the last part of the Cretaceous Period. This discovery increases the documented diversity of the paleofauna from the Upper Cretaceous succession in southeastern Turkey and provides new insights into the paleoenvironment of the carbonate ramp of the northern Arabian plate, and the paleobiogeography of Campanian gastropods in general.

A new eryopid temnospondyl, Stenokranio boldi n. gen. n. sp. is described based on well-preserved cranial and postcranial material from fluvio-lacustrine deposits of the Permo-Carboniferous (Gzhelian/Asselian) Remigiusberg Formation at the Remigiusberg quarry near Kusel, Saar–Nahe Basin, southwest Germany. The new taxon is characterized by three autapomorphies within the Eryopidae: (1) the relatively narrow posterior skull table, therefore nearly parallel lateral margins of the skull; (2) the short postparietals and tabulars; and (3) the wide ectopterygoid. Phylogenetic analysis reveals a monophyletic Eryopidae with the basal taxa Osteophorus, Glaukerpeton, and Onchiodon labyrinthicus forming a polytomy. Actinodon may be either a basal eryopid or a stereospondylomorph, and the genus Onchiodon is not monophyletic. Stenokranio n. gen. is found as a more derived eryopid forming the sister taxon to Eryops. Stenokranio n. gen. was among the largest predators of the Saar–Nahe Basin. Its semiaquatic lifestyle enabled Stenokranio n. gen. to browse riverbanks and lake shorelines for prey, but most likely it fed on aquatic vertebrates. Stenokranio n. gen. was part of a faunal assemblage of aquatic, semiaquatic, and fully terrestrial vertebrates, such as sarcopterygian and actinopterygian fishes, xenacanthid sharks, a dvinosaurian temnospondyl, different “lepospondyls”, diadectomorphs, and synapsids. This is in general accordance with the vertebrate community from the Permo-Carboniferous of North America and from the early Permian localities of Manebach (Thuringian Forest Basin) and Niederhäslich (Döhlen Basin). It is notable that the occurrence of Stenokranio n. gen. and other eryopids in these localities excluded the presence of other large temnospondyls such as Sclerocephalus. However, a previously described isolated eryopid mandible from the Remigiusberg locality differs from that of Stenokranio n. gen. in several characters, implying that probably two different eryopid taxa lived at the same locality.

UUID: www.zoobank.org/88a52547-d6fc-40af-965c-a6786c252ed5

Platymerella from the lower Red Mountain Formation in Georgia and Tennessee, the Bowling Green Dolomite of west-central Illinois, and the Elwood Dolomite of northeastern Illinois represents a paleosubtropical, cool-water occurrence of virgianid brachiopods in Laurentia during the early Silurian (middle–late Rhuddanian). These occurrences were located in the southern Appalachian foreland basin and the distal end of the Sebree Trough, likely subjected to frequent cool-water current and upwelling from Gondwana. Compared with broadly coeval species of Virgiana from lower paleotropical to equatorial latitudes, Platymerella has significantly smaller, dorsoventrally flattened shells, with subequal ventral and dorsal umbones and beaks that extend only slightly above the hinge line. Relative to its shell size, however, Platymerella has more prominent thickening of the shell wall, median septum, spondylium, and hinge plates than Virgiana, resembling more closely the extravagant shell thickening of Tcherskidium and Proconchidium from the Late Ordovician (late Katian) equatorial regions. The thickening of hinge plates resulted in the formation of a pseudocruralium, which separates Platymerella from Virgiana. In latest Ordovician–earliest Silurian virgianids, there was a general morphological gradient toward a smaller shell, reduction in the ventral-valve convexity, and reduction in the size and height of the ventral umbo from paleoequatorial to southern subtropical regions, with Platymerella representing the most southerly forms.

The type specimens of Eothinoceras americanum Ulrich et al., 1944, type species of the genus Eothinoceras Ulrich et al., 1944, are revised based on new photographic material. The resulting interpretation of the conch shape of Eothinoceras shows that the type species is an endogastric cyrtocone, necessitating the restriction of Eothinoceras to the type species and requiring the revision of the family Eothinoceratidae and the order Cyrtocerinida. A new scheme for classifying the genera of the order Cyrtocerinida into its three families is proposed: (1) Eothinoceratidae Ulrich et al., 1944, containing the genera Eothinoceras; Protothinoceras Chen and Teichert, 1987; Mesothinoceras Chen and Teichert, 1987; and Conothinoceras Chen and Teichert, 1987; (2) Cyrtocerinidae Flower, 1946, including Cyrtocerina Billings, 1865; Tangshanoceras Chen, 1976; and Centrocyrtocerina Stait, 1983; (3) Bathmoceratidae Gill, 1871, containing Bathmoceras Barrande, 1865; Saloceras Evans, 2005; Sacerdosoceras Evans, 2005; Margaritoceras Cecioni and Flower, 1985; and Mutveiceras Cichowolski et al., 2014.

Lobopodians are an iconic and diverse group of animals from the Cambrian, which alongside radiodonts, present an important window into the evolution of arthropods and the development of Paleozoic ecosystems. Of these, a rare few species outside of Radiodonta possess lateral swimming flaps. The recent discovery of Utahnax provided much-needed insight into the evolution of swimming flaps, suggesting that the ventrolateral flaps of Kerygmachela evolved independently from other flap-bearing lobopodians and radiodonts. Here a new pelagic lobopodian species is described, Mobulavermis adustus new genus new species, the first lobopodian to be reported from the Cambrian-age Pioche Shale of Nevada. Mobulavermis adustus was large and possessed more ventrolateral flap pairs than any other known lobopodian or radiodont. It is found to be a close relative of both Kerygmachela and Utahnax, allowing the establishment of the new lobopodian family Kerygmachelidae new family. In addition, an indeterminate euarthropod fossil from the Pioche Formation is described in brief, and the recently described Chengjiang species Parvibellus avatus Liu et al., 2022, thought to have been related to the “gilled lobopodians,” is reinterpreted as a juvenile siberiid lobopodian.

UUID: http://zoobank.org/759c4eb9-ec60-4d5a-8b20-4f115ab79575

The trilobite Needmorella new genus, with type species N. simoni new genus new species from the late Emsian to mid-Eifelian Needmore Shale of West Virginia, is a distinctive member of the subfamily Synphoriinae. It also occurs in the same formation in Pennsylvania and Virginia. It is not very similar to other Devonian representatives of the subfamily and is considered to have its origins in a morphologically less-derived ancestor because it shares certain similarities with Silurian genera, including the very short anterior cephalic border unmodified by crenulations or spines, S2 that is not largely reduced to a deep pit adaxially, the relatively low inflation of L3, and the well-defined interpleural furrows on the pygidium. Other particularly distinctive characters of the genus include the very long genal spines and the abaxially inflated and expanded posterior pleural bands on the thorax and pygidium that project slightly distally. The conventional concept of the Devonian synphoriine Anchiopsis Delo, 1935 appears to be incompatible with the holotype of the type species, judging from the early illustrations of the specimen, and the genus could be a synonym of Synphoria Clarke, 1894.

UUID: http://zoobank.org/4a820e27-54ec-4f7b-a408-675e62b75154

The Cambrian (Jiangshanian, Sunwaptan) Honey Creek Formation in the Wichita Mountains region of Oklahoma yielded a new fauna dominated by Monocheilus Resser, 1937 (senior synonym of Stigmacephalus Resser, 1937) in association with Ptychaspis Hall, 1863. It occupies the same stratigraphic position as similar faunas in the Upper Mississippi Valley and Alberta, lying a little above an interval characterized by species of Taenicephalus Ulrich and Resser in Walcott, 1924 and Orygmaspis Resser, 1937. Revision of Ptychaspis bullasa Lochman and Hu, 1959 from type material from Idaho and sclerites attributed to the species from Texas reveals a plexus of pseudocryptic species that share tuberculate sculpture on the cranidium. New species are Monocheilus reginae, Monocheilus richardi, Ptychaspis occulta, and Ptychaspis matuszaki.

UUID: www.zoobank.org/c2771c63-db4b-434a-ae58-3e3fda19ecb0

Trilobites from the upper Guzhangian of the southern Argentine Precordillera, preliminarily described by Carlos Rusconi in the 1950s, are revised herein. The specimens studied were collected from an allochthonous limestone block of La Cruz Olistoliths at 200 m northwest of Estancia San Isidro locality (San Isidro area, Mendoza). Taxa comprise Kormagnostus seclusus (Walcott, 1884), Cedaria prolifica Walcott, 1924, C. puelchana Rusconi, 1954, Tricrepicephalus texanus (Shumard, 1861), Meteoraspis metra (Walcott, 1890), Coosia conicephala (Rusconi, 1954) new combination, Coosella texana? Resser, 1942, Nasocephalus cf. N. nasutus Wilson, 1954, and Olenoides proa (Rusconi, 1954) new combination. The North American genera Meteoraspis Resser, 1935 and Nasocephalus Wilson, 1954 are reported confidently from South America for the first time. This assemblage is representative of the Cedaria prolifica Zone, which correlates with the lower Crepicephalus Zone of the traditional North American genus-based zonation. Most of the genera and species identified were previously described exclusively from Canada, the United States, and northwestern Mexico, a fact that provides new support to an allochthonous Laurentian origin of the Argentine Precordillera.

Atrypoidea is a Silurian smooth atrypide with a worldwide distribution and high species-level diversity especially during Ludlow to Prídolí. In this study, the occurrences of 67 species, 14 subspecies, and 23 forma, cf., aff., or var. species are summarized. Among them, Atrypoidea recta from Aeronian of Siberia is the earliest known occurrence of this genus, while Atrypoidea elatior or Atrypoidea polaris modica from upper Prídolí strata of the Czech Republic and China, respectively, should be the youngest species. No valid Devonian occurrence of Atrypoidea has been recorded due to absence of convincing identification or poor stratigraphic information. The rapid evolution and cosmopolitan nature of Atrypoidea allow some species to be used as index fossils for strata of Ludlow and Prídolí in South China. The age of the Chejiaba Formation in Guangyuan, Sichuan Province, South China, has been clarified based on the occurrence of Atrypoidea. Specimens from this locality, which are preserved in situ, are described herein and illustrated with reconstruction of life style for the first time.