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.

The Llandoverian (Telychian) Schoolcraft Formation of Schoolcraft County in the Upper Peninsula of Michigan includes several intervals of exceptional preservation marked by abundant specimens of the noncalcified macroalga Thalassocystis striata Taggart and Parker, 1976. Here, two new noncalcified macroalgal species are described from one of these algal-Lagerstätten intervals. The monopodial thallus of Archaeobatophora gulliverensis new species resembles that of the living dasycladalean green alga Batophora Agardh, 1854 and consists of a cylindrical main axis bearing whorls of branched laterals. It is the second species to be assigned to Archaeobatophora Nitecki, 1976, the type species of which is known only from the Upper Ordovician of neighboring Delta County and the diagnosis of which is emended herein. The thallus of Earltonella swinehartii new species consists of a horizontal stolon that bears a series of upright pinnate fronds. This taxon broadly resembles the living bryopsidalean green alga Caulerpa Lamouroux, 1809 and is the second species to be assigned to Earltonella LoDuca in LoDuca et al., 2023, a genus otherwise known only from approximately age-equivalent strata in the Lake Timiskaming area of Ontario. Additionally, a new Thalassocystis striata occurrence is reported from the Schoolcraft Formation in neighboring Mackinac County, extending eastward the geographic range of this Codium-like bryopsidalean taxon within the Michigan Basin. Viewed in broader terms, the two new species show complex thallus morphologies consistent with a previously documented large-scale morphological pattern in the early Paleozoic evolutionary history of macroalgae and contribute to an emerging understanding of major early Paleozoic radiations of both dasycladalean and bryopsidalean algae that produced, by the mid-Silurian, diverse floras of siphonous green macroalgae broadly similar to those that thrive today in Florida Bay and the Bahama Banks.

Precambrian organic-walled microfossils preserved in fine-grained sedimentary rocks constitute the earliest fossil record of eukaryotic life. The Mesoproterozoic–Neoproterozoic transition coincided with major innovations in the evolution of early eukaryotes, including the radiation of crown-group lineages, represented in these rocks by candidate red algae, green algae, and fungi. However, the diversity of these early eukaryotes is yet to be fully explored. Here, we present a systematic description of the microfossil assemblage preserved in exceptional detail within sedimentary phosphatic nodules and bands in the Diabaig Formation of the ca. 1-Ga Torridon Group of northwest Scotland. Recent work has highlighted the lacustrine or estuarine nature of its depositional environment and confirmed that these fossils may include the oldest known non-marine eukaryotes. We identified 11 morphotaxa from newly collected material, including the new genus and species Minimarmilla multicatenaria, two undoubted eukaryotes, and two probable eukaryotes. The latter include Pterospermopsimorpha sp., and a new network-forming unnamed taxon. These microfossils present an important window on eukaryotic diversification in non-marine aquatic environments during the Mesoproterozoic–Neoproterozoic.

UUID: http://zoobank.org/5829c401-04fc-4229-9136-3963275826c6

A new species of Blastulospongia Pickett and Jell, 1983 from the middle Cambrian Devoncourt Limestone, Georgina Basin, Australia exhibits distinct perforation patterns characteristic of sphinctozoans. Recognition as a sphinctozoan-grade sponge confirms the poriferan affinity of this enigmatic genus, which appeared prior to the development of other hypercalcified sponge forms of chaetetids and stromatoporoids. Blastulospongia bouliaensis new species occurs together with four species of primitive spicular radiolarians: Echidnina irregularis Won in Won and Iams, 2002, Parechidnina aspinosa Won in Won and Below, 1999, Palaeospiculum reedae Won in Won and Below, 1999, and Palaeospiculum devoncourtensis Won in Won and Below, 1999. Micro-computed tomographic (MCT) analysis of Parechidnina aspinosa reveals its skeletal construction through the fusion of unirayed spicules, indicating a close phylogenetic link with archeoentactinids. Blastulospongia bouliaensis n. sp. and Palaeospiculum devoncourtensis represent promising Miaolingian accessory species for biostratigraphy during the Drumian-Guzhangian interval.

UUID: http://zoobank.org/a74cdd4d-6bc3-427b-bf4c-d4f0b79a5c91

Ostracods from the late Mississippian–early Pennsylvanian (late Serpukhovian–Bashkirian) from the Calingasta–Uspallata Basin, Precordillera Argentina, are studied for the first time. The analyzed successions (Hoyada Verde, El Paso, Leoncito, and Yalguaraz formations) document the most widespread glacial event in southwestern Gondwana during the Late Paleozoic Ice Age. One new species, Aechmina cuyanensis new species, is defined, and seven species are described, two of which are new records for South America. The distribution of Carboniferous ostracods in the Argentine basins (Calingasta–Uspallata, Río Blanco, and Tepuel–Genoa) is discussed, highlighting the interesting record of this fauna in levels between or below diamictites and its absence in the mudstone interval with no evidence of glaciation. The association is characterized by ornamented palaeocopids, one binodicopid, and some metacopid species corresponding to the Assemblage III of the Eifelian Mega-Assemblage, indicating a slightly hypoxic and very calm environment between the fair-weather wave base and the storm wave base.

UUID: https://zoobank.org/68fda8dc-be98-4a03-b369-a696b7d7ad99

The phylogenetic relationships among arthropods remain contentious because morphological studies face challenges in resolving certain branches. Particularly difficult are relationships within and between the stem arthropods, owing largely to too few well-preserved fossil representatives. Additional fossil evidence, particularly from exceptional deposits like the Silurian Waukesha Lagerstätte in Wisconsin, helps to bolster our views on the evolutionary history of arthropods by providing well-preserved examples of novel taxa that could fit between early diverging stem-arthropod clades and modern euarthropods, thus building possible bridges between the two. Formed in karstification-induced troughs of the Manistique Formation paleoslope, the Waukesha Lagerstätte preserves a unique biota of organisms from the Telychian Age, mostly through secondary precipitation of francolite. Perhaps most well known from this deposit are the many peculiar and enigmatic arthropod taxa that could help resolve early arthropod cladistic relationships. We add to the growing body of work on the diversity, phylogeny, and taxonomic descriptions of the Waukesha biota by detailing a previously unnamed bivalved arthropod, informally called ‘the butterfly animal’ in past literature—which we here designate as Papiliomaris kluessendorfae n. gen. n. sp. We also conducted a Bayesian phylogenetic analysis that placed several recently described Waukesha taxa as basal members of the ‘Mandibulate’ clade within the Euarthropoda.

UUID: http://zoobank.org/c1d6f1dc-d35f-420c-aa57-2c8983f9779e

Benthic gastropods are not commonly useful for biostratigraphic zonation. The gastropod genus Plocezyga is abundant throughout the marine units of the Desmoinesian through Virgilian Pennsylvanian strata in the United States. The protoconch of Plocezyga gives evidence that it had a planktonic time within its life cycle, which would give it a wider regional distribution. It has been found that Plocezyga is able to biostratigraphically zone the Pennsylvanian of the United States by use of first-occurrence range zones. The upper Atokan stage through the Virgilian Stage can be zoned using of the first occurrences of Plocezyga conica, P. excellens, P. ampla new species, P. costata, P. subquadrata, P. ornata, P. acuminata, P. obscura, and P. procera new species. The lower and upper boundary of the Desmoinesian as well as the lower boundary of the Missourian Stage are defined by these gastropod zones. Six new species are proposed: Plocezgya ampla from upper Desmoinesian units; Gamizyga lenterotunda from Missourian units; and Plocezyga pingurestis, Plocezyga procera, Cyclozyga promohumera, and Cyclozyga diversarevolvi from Virgilian units.

UUID: http://zoobank.org/d070c5ad-b65f-4ab1-842f-36058704a335

This work describes and discusses Permian ammonoid faunas collected in two stratigraphic sections from the Las Delicias Formation of Coahuila state, northern Mexico. The taxa identified comprise 18 species, including Demarezites quirozii new species, as well as Mexicoceras smithi (Miller and Furnish, 1940), a variety of Mexicoceras guadalupense (Girty, 1908) here upgraded to specific status. The systematic analysis of the species found allowed us to recognize two middle Permian faunal zones, represented in ascending order by the Waagenoceras dieneri-Adrianites elegans Biozone from the Wordian and the Timorites schucherti-Cibolites uddeni Biozone from the Capitanian. Thus, the relative age of the Las Difuntas-18 section is established as Wordian (middle Guadalupian), whereas the Las Manuelas I section is Wordian–Capitanian (middle–upper Guadalupian). Both ammonoid zones are correlated with those recorded in Guadalupian outcrops from the southern USA, northeastern Japan, and southern China. This faunal resemblance between Mexican ammonoids and those taxa reported in these regions (USA, Japan, and China) supports the proposal that during the middle Guadalupian there was a marine corridor through the Panthalassa Ocean, which could have connected the Paleotethys and North American regions. It should be noted that ammonoids of both studied sections from the Las Delicias Formation were correlated better with West Texas (USA) and British Columbia (Canada) faunas, which are included in the North American Realm.

UUID: https://zoobank.org/60c6c43c-6536-4fbf-a372-c610bec86626

This work expands the knowledge on the diversity of Ordovician cephalopod assemblages of peri-Gondwana by describing 16 straight-shelled, annulated and/or reticulately ornamented specimens from the late Darriwilian and late Katian strata of the Prague Basin (Central Bohemia). Preservation facilitated the micro-CT investigation of internal shell structures in one of the specimens; in other specimens, the siphuncle and septa are not preserved, and these specimens are thus left in open nomenclature. In total, six species are recognized with one new species established: Anthoceras? sp. A, Anthoceras? sp. B, Sactorthoceras pustulatum new species, Dawsonoceras? sp. indet., Kionoceras? sp. indet., and Palaeodawsonocerina obscurum new combination. In addition, the holotype of Orthoceras evictum was examined and re-interpreted as a conulariid rather than a cephalopod. Paleogeographically, these taxa indicate mixed Baltican, Avalonian and peri-Gondwanan affinities for the late Darriwilian and late Katian cephalopod assemblages.

UUID: http://zoobank.org/fcf79203-e864-47ed-bf71-12f475fa55a9

Xandarellida is a clade of artiopodan euarthropods known exclusively from the early Cambrian (Series 2, Stage 3) Chengjiang biota of South China, apart from the possible inclusion of Phytophilaspis Ivantsov, 1999 from the early Cambrian Sinsk Biota of Siberia. A rare euarthropod taxon represented by four specimens from the Emu Bay Shale (Cambrian Series 2, Stage 4) of Kangaroo Island, South Australia, represents the first record of Xandarellida from East Gondwana. A new monotypic genus, Austroxandarella n. gen., is based on A. poikar n. sp., being most readily distinguished by its elongate pygidium. Close affinities to Xandarella Hou et al., 1991 are suggested by a thorax of 10 tergites, with progressive elongation of the posterior three tergites relative to the seven anterior tergites of subequal length—this elongation representing the dorsoventral decoupling of biramous appendage pairs and tergites shared by all xandarellids. Discovery of an Australian xandarellid adds more support for biogeographic affinities between East Gondwana and South China in the early Cambrian.

UUID: https://zoobank.org/8a0f56ec-6d12-49ee-8ffd-a8dca97df99f

Abrupt appearance of the dikelocephalid trilobite genus Osceolia in later Cambrian strata of the upper Mississippi Valley immediately above a flooding surface is succeeded by widespread regional occurrence among approximately eight parasequences in the early part of a falling stage systems tract. All of Osceolia’s sclerite types are illustrated for the first time. The taxonomy is revised to recognize two species, of which O. tumerispina is new and known only from a dolomitic horizon at a single locality. All five of Ulrich and Resser’s (1930) Osceolia species are synonymized within O. osceola (Hall, 1863), a species widespread in regional dolomitic mudstones and feldspathic sandstones. Osceolia osceola shows notable polymorphism in the presence of an axial ledge in the anterior cranidial border. Holaspid ontogenetic variation evident within bedding-plane collections of O. osceola scales with that occurring among collections and across facies. Collection-related morphological differences among the samples beyond those related to size are subtle. The occurrence of larger individuals in more distal settings may reflect ontogenetically related habitat preference. Osceolinae Ulrich and Resser, 1930 is rejected. The closest relatives of the two Osceolia species may occur outside of the upper Mississippi Valley. Material of a local, stratigraphically older, and possibly related Ulrich and Resser 1930 nomen nudum is figured and described for the first time. Osceolia’s cranidial morphotype was converged upon several times during the evolution of Cambrian trilobites among relatives both phylogenetically close and distant.

UUID: http://zoobank.org/bdd2cf1b-331f-4204-8957-eadce195610d

New, well-preserved specimens of the paracrinoids Wellerocystis and Implicaticystis provide new morphological data. All specimens originate from reef facies in the Kimmswick Limestone (Upper Ordovician, Sandbian–Katian) at a single locality near St Louis, Missouri, USA. Wellerocystis is characterized by an ovoid theca largely composed of imperforate plates arranged in vertical columns lacking pore-structures but with fine granular sculpture; four recumbent branched uniserial ambulacra with up to seven branches in total; a mouth frame of four plates, one of which also contributes to the periproct frame; a sinuous hydropore; and circular gonopore. The stem is unknown; its facet is small and circular, similar to that of Platycystites. Implicaticystis is characterized by a circular, heteromorphic stem, ovoid theca composed of externally concave, perforate plates with foerstepores, internal pararhombs, and a mouth frame of three plates plus two lateral plates each bearing two facets for erect, uniserial, hemipinnate pseudoarms. Foerstepores connect to tubes that pass through the theca near plate sutures. Internal lamellae of pararhombs support thecal plates much as A-frames support ridged rooves. Erect versus recumbent and branched ambulacra evolved repeatedly in pelmatozoans so both are less useful in classifying paracrinoids than presence or absence of unique pore-structures. The sister group of paracrinoids could have included Columbocystis, rhipidocystids, and cryptocrinitids. Columbocystis is commonly mentioned in discussions in this context, but its asymmetrical facets suggest it had biserial feeding appendages, unlike uniserial paracrinoid appendages.

Numerous fish microremains, including diverse chondrichthyans, have been recovered for the first time in the Carboniferous–lower Permian of the Naqing, Narao, and Shanglong deep-water sections from Guizhou Province, South China, as well as in the Serpukhovian–lower Bashkirian of the Sholaksay section from Kazakhstan. The richest assemblage was found in the Bashkirian strata of the three South China sections. These findings are the first reliable record of Pennsylvanian fishes in China. The fish assemblage from the Sholaksay section and the Bashkirian of China closely resemble those from the same interval in the Aksu section, Uzbekistan. All studied fish faunas from these three Asian regions are associated with the Paleotethys. Notably, while Bashkirian chondrichthyan faunas generally exhibit low taxonomical diversity in many regions of the world, the deep-water fish assemblages from South China, Kazakhstan, and Uzbekistan are characterized by high taxonomical diversity. The fish fauna includes widely distributed chondrichthyan taxa; however, Gissarodus occurs only in these three Asian regions.

Despite the lesser preservation of bat fossils compared to karstic sites, fluviolacustrine deposits are of crucial importance for assessing the local palaeodiversity of bats. This was confirmed by three faunas from the upper Miocene of Slovakia (Borský Svätý Jur, MN9; Studienka A, MN9; Krásno, MN11), which comprise seven species—Miostrellus cf. Miostrellus noctuloides (Lartet, 1851), Myotis cf. Myotis murinoides (Lartet, 1851), ‘Otonycteris’ sp. indet., Miniopterus sp. indet., Vespertilionidae gen. indet. sp. indet. 1, Vespertilionidae gen. indet. sp. indet. 2, and Rhinolophus cf. Rhinolophus grivensis Depéret, 1892. Bats represent ~ 1.40% of the small mammal remains from Borský Svätý Jur, ~ 0.25% of those from Studienka A, and ~ 1.78% of those from Krásno. The MN11 fauna from Krásno consists of six distinct species, which is unusual for a Miocene fluviolacustrine deposit. Most likely, this is the consequence of the relatively high frequency of bats in the taphocoenosis, therefore providing a more complete and more accurate picture of the Carpathian late Miocene bat faunas. This material encourages the study of fluviolacustrine deposits to unravel the cryptic diversity of Neogene taxa.