This work describes a rhynchonellid and spire-bearing brachiopod fauna from the Ixtaltepec Formation of Oaxaca, Mexico. Leiorhynchoidea perrilliatae, Allorhynchus scientiana, and Anthracospirifer oaxacaensis are new species. The specific determination, along with information of previously described taxa, allowed the establishment of precise relative ages of the different fossiliferous intervals (API-1 to API-8) of the formation. The occurrence of Serpukhovian taxa in API-1 to API-3 allowed assignment of the strata to the Upper Mississippian. The presence of Bashkirian species allowed the assignment of the rocks of API-5 and API-6 to the Lower Pennsylvanian. Likewise, Middle Pennsylvanian brachiopods in API-7 and API-8 enabled correlation of the strata with the Moscovian stage. This study shows that the Ixtaltepec Formation is represented by a succession of well-delimited Serpukhovian, Bashkirian, and Moscovian rocks. Regarding paleogeography, the brachiopod fauna displays clear taxonomic variations that concur with global geological changes that occurred between the Serpukhovian to Moscovian. In the Serpukhovian intervals, we recorded numerous cosmopolitan taxa of tropical waters, coinciding with the migration pathway of the Rheic Ocean. For the Bashkirian, we observed a North American provincialism; however, because of the presence of Australian and South American species, it is proposed that the Austropanthalassic-Rheic corridor had a close connection with Oaxaca. The main provincialism was observed in the Moscovian association because most of those taxa have been reported from different localities in the United States. This study supports that the main resemblance between Oaxacan and North American faunas continued until the Pennsylvanian and not the Mississippian, as was previously proposed.

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This work provides the detailed investigation (taxonomy, biostratigraphy, and paleoecology) of a nonmarine ostracod fauna from the Shinekhudag Formation in Gobi–Altai area, southwest Mongolia. The samples from two sections (Tsagaan Tsuvarga and Oshih Hollow East) yielded various ostracods assigned to nine species belonging to six genera: Cypridea verrucata Neustrueva, 1974, C. ihsienensis Hou, 1958, C. unicostata Galeeva, 1955, C. tumefacta Neustrueva, 1974, Yumenia cf. Y. oriformis Hou, 1958, Scabriculocypris subscalara Zhang and Chen in Ye et al., 2003, ?Trapezoidella sp., Candona sp., and Vlakomia ulanense Neustrueva, 1977. The biostratigraphic application of our taxonomic results suggests that the age of the Shinekhudag Formation is Barremian–Aptian. In addition, the ostracod fauna shows strong affinities to faunas from northeast China and potentially northwest China, providing evidence of faunal exchanges between these regions and southwest Mongolia. The new discovery of Vlakomia ulanense indicates that mid-Cretaceous (Albian) species in northeast China probably originated in Mongolia at the time of deposition of the Shinekhudag Formation. Two ostracod assemblages in the studied sections reflect that different paleoenvironment settings have existed during deposition; the Tsagaan Tsuvarga Section represents a shallow-littoral zone of athalassic (inland) saline lake under arid climate, and the dominance of cypridoideans of the Oshih Hollow East Section is indicative of ephemeral water bodies.

The oldest known fossil mysid (order Mysida) Aviamysis pinetellensis n. gen. n. sp. is described here from two nearly complete specimens found in the Alcover unit from El Pinetell (Catalonia). It differs significantly from other Mysida and is placed in a new genus assigned to the family Mysidae and tentatively to the subfamily Boreomysinae. These specimens represent the first described mysid material from the Alcover outcrops (Middle Triassic, upper Ladinian, 235–242 Ma), extending the known geological range of the poorly understood fossil fauna of the order Mysida by at least 70 Myr.

A very early juvenile specimen of Hypselocrinus hoveyi with arms and partial column attached is utilized to examine the growth in this Mississippian advanced cladid crinoid. The aboral cup height of this specimen is 4 mm. In contrast to results reported in previous studies of crinoids, Hypselocrinus hoveyi grew with a combination of allometric and isometric growth. Different plates of the aboral cup grew with a combination of growth modes, and arms grew with allometric growth or relative change in shape that was not strict allometry.

The oligopygoid echinoid Haimea bajasurensis n. sp. is described from middle lower Eocene (”Capay Stage”) shallow-marine sandstones in the middle part of the Bateque Formation and shallow-marine limestones in the upper part of the Tepetate Formation, Baja California Sur, Mexico. The new species is both the earliest and the westernmost oligopygoid, and the first occurrence of Haimea in North America.

Dentalium martini Whitfield, 1882, is a calcareous worm tube, not a mollusk, and is placed in synonymy of Coleolus crenatocinctum Hall, 1879. The growth of D. martini mimics logarithmic curvature in the holotype, but in other specimens shape varies from irregularly curved to straight. A prime reason for reassignment is variation of the wall thickness around the circumference in D. martini, which in late Paleozoic and Recent scaphopods of the same size is of uniform thickness.

Siliceous sponges are rare in the Cretaceous-Paleogene record, with only a handful of published accounts from the Southern Hemisphere. Variously preserved siliceous sponges, both Hexactinellida and Demospongiae, have been recovered from the Takatika Grit (Campanian-Danian), Chatham Islands, New Zealand. Hexactinellid sponges are represented by the Euretidae Eotretochone australis n. gen. and sp., Pararete sp., and Euretid gen. and sp. indet., Auloplax? sp. (Dactylocalycidae) and Tretodictyiid gen. and sp. indet., as well as by loose hexactines and fragments of dictyonal skeletons. Demosponges are represented only by loose spicules typical of Astrophorida, and perhaps lithistids. These fossils represent the first account of sponges of this age from the New Zealand region of the southwest Pacific.

Truncatoflabellum has been considered a free-living genus that exhibits both sexual and asexual phases; divided lower coralla (anthocauli) are specialized for asexual reproduction by transverse division through a decalcification process, whereas the upper coralla (anthocyathi) only undertake sexual reproduction, in a life-cycle strategy that includes a distinct alternation of generations. However, little evidence has been presented to support this idea of its life cycle. We elucidate the life mode of Truncatoflabellum by identifying key fossil characters (e.g., multiple rejuvenations and decalcification records just beneath lateral spines) and statistically analyzing the size distributions of over 500 individual coralla. Results of those morphological and biometric analyses clearly indicate alternation of generations in the life cycle of Truncatoflabellum.

The Cretaceous miospore Microreticulatisporites sacalii (Deák and Combaz) n. comb. occurs in the Dakota Formation of Iowa and the lower Tuscaloosa Group of Louisiana and Mississippi. These occurrences represent the first reported from North America. The presence of the species in mid-Cretaceous strata of North America is consistent with the upper Albian to Cenomanian interval from which it has been recorded in Europe. Review of the morphology of these spores and the systematics of the genus Vadaszisporites, to which the species originally was assigned, require transfer of the species and suppression of Vadaszisporites as a junior synonym of Microreticulatisporites Knox emend. Potonié and Kremp, 1954.

Praehyalocylis cretacea (Blanckenhorn, 1889), a pteropod previously known only from upper Eocene to middle Miocene strata in Europe and Turkey, is reported for the first time in similar age rocks in the northwestern United States. Of the 238 specimens, most occur as molds and casts in concretions in deep-water deposits from the Keasey Formation in Oregon, and from the Quimper Sandstone, Blakeley Formation, Pysht Formation, and Astoria Formation of Washington. Praehyalocylis has not been reported previously from the Western Hemisphere.

Clio berglundi n. sp. and C. goederti n. sp. are reported from upper Oligocene to lower Miocene rocks in Washington. Eleven specimens were found mostly as internal molds in concretions in deep-water deposits of the Lincoln Creek, Pysht, and Astoria Formations of Washington. Cenozoic species of Clio have not been reported previously from the West Coast of the United States.

Palynoflorules containing sparse but regularly occurring chitinous-walled fungal, probably ascomycete, spores have been obtained from silty limestone nodules in the Jurassic Coon Hollow Formation in the Wallowa terrane in Hells Canyon, Idaho. The fungal spores are associated with moderately abundant embryophytic spores and pollen that suggest late Early Jurassic to early Middle Jurassic age, which agrees with dating provided by marine animals stratigraphically just above. The fungal spores constitute the most diverse such assemblage of robust-walled spores described from pre-Cretaceous rocks. Two new species of the fossil fungal spore form-genus Diporicellaesporites, D. idahoensis and D. serratulus, and one new species of form-genus Fractisporonites, F. pittsburgensis, are described.

Here we report and describe a new assemblage of Thylacocephala (Crustacea) from the late Spathian (Early Triassic) of Chaohu, Anhui Province, South China. The assemblage consists of at least three species from different genera: the small-sized Microcaris rectilineatus n. sp. appears the most abundant, while the large-sized Ankitokazocaris sp. and Diplacanthocaris chaohuensis n. gen. n. sp. are rare. A morphometric analysis of the carapace outline separates Diplacanthocaris chaohuensis n. gen. n. sp. from other genera. Along with Ankitokazocaris chaohuensis Ji et al., 2017 and Kitakamicaris sp. from the horizon 28 m above this assemblage, four different genera of Thylacocephala occur in the Chaohu Fauna. With additional materials reported from Japan and North America, the Early Triassic is now known as the period when Thylacocephala reached their highest diversity and widest geographical distribution. Thylacocephala quickly diversified shortly after the Permian–Triassic mass extinction, probably because of their ability to survive in a relatively low-oxygen environment. Thylacocephalan fossils from Chaohu are found in dense concentrations, suggesting they might have constituted a food source for the fishes and marine reptiles in the Chaohu Fauna.

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A nonmarine pelecypod occurrence was reported in 1977 within a zone of gray shaly mudstones yielding carbonized plants at Promontory Butte, Mogollon Rim, east-central Arizona. On paleobotanical evidence, the zone appeared then to be either of Late Carboniferous or Early Permian age. Work on 50 measurable shells indicates that the fauna is of Anthraconaia protracta Eagar and has wide variation. Standard dimensions of the Arizona fauna are identical to those of the type assemblage of A. protracta, which forms a thin band immediately above the Benwood Limestone of the Monongahela Group near Pittsburgh, Pennsylvania, 2,700 km to the east. The Arizona shell varieties match 50–60 percent of those from the band in Pennsylvania. Matching falls off rapidly to nil 70 m below this horizon and 100 m above it. Small differences in the trends of variation of the shells from Promontory Butte and Pennsylvania are accompanied by small differences in their respective host sediments, as reflected in their organic carbon and carbonate contents. When these results are compared with earlier conclusions on recurrent, apparently ecophenotypic, changes in the shape of Anthraconaia from other horizons in the Carboniferous and Lower Permian, they provide further evidence that the Arizona and Pennsylvania faunas were approximately contemporary. When the two bands are correlated, the Promontory Butte band is placed in the upper Pennsylvanian and in the upper Virgilian as traditionally accepted.

A disc-like soft-bodied fossil recovered from the Farmers Member of the Borden Formation in northeastern Kentucky is described and is interpreted as a chondrophorine float, an internal feature. This is apparently the first report of a post-Devonian fossil porpitid.

Agnotocastor readingi n. sp., from the Orellan of Nebraska, is intermediate in size between the Chadronian A. galushai Emry from Wyoming and the Orellan A. coloradensis Wilson from Colorado. It differs slightly in dental and mandibular morphology from these latter species and cannot be transitional between them. The simplification of the dentition in A. readingi may indicate a position ancestral to the Whitneyan A. praetereadens Stirton from South Dakota.

A new gastropod genus, Dutrochus, is established for members of the family Microdomatidae that are characterized by a reticulate ornament of spiral cords and intersecting, finer collabral threads, with all but one spiral cord being of nearly equal strength, and the single remaining cord being of stronger (nearly twice the order) magnitude and being situated at the periphery. It is represented by the type and only known species, Dutrochus alaskensis n. gen. and sp., from the upper part (lower Middle Devonian; lower Eifelian) of the Lower? and Middle Devonian Cheeneetnuk Limestone, McGrath A-5 quadrangle, west-central Alaska. The genus is very close and nearly homeomorphic to the Permian microdomatid genus Glyptospira, but differs from the latter in possessing an extremely strong, peripheral spiral cord and an extremely thick, multi-layered apertural margin.

The floras and the faunas encountered in the Mabou Mines Section of Cape Breton Island, Nova Scotia, are not greatly diversified. The floras are composed mainly of medullosean (seed) ferns referable to neuropterids and reticulopterids. Infrequently encountered are lycopod, pecopterid, mariopterid, alethopterid, fortopterid, sphenopterid, sphenophylls and cordaitean fossils. The fauna is characterized by Anthraconauta phillipsii, Carbonita spp., Leaia spp. and rare Gutschickia bretonensis representing a fresh-water, lacustrine paleoenvironment in a fluviatite regime. Shells possibly referable to Anthraconauta tenuis s.l. are rare.

In European chronostratigraphy (i.e., Heerlen), the age of the Mabou Mines Section encompasses middle to late Westphalian C to early Westphalian D. Correlation of the fauna with British chronozones is not without difficulty and a phillipsii Chronozone assignment is proposed which is somewhat lower (Westphalian C) than the floral correlation, an expected result.

A new species of phyllocarid arthropod, Tropidocaris salsiusculus, is described from the Upper Devonian Hampshire Formation near Rowlesburg, West Virginia. The organism was found in association with numerous trace fossils, at least one of which could have been produced by T. salsiusculus, and body fossils, including Lingula sp., several bivalve mollusks and smooth ostracods. Collectively, these organisms suggest a brackish-water environment of deposition. This report represents only the third record of phyllocarids from West Virginia.

Two new specimens of a trigonotarbid arachnid are described from Upper Pennsylvanian (Virgilian) rocks of Kansas, U.S.A., from a horizon which elsewhere has yielded scorpion and mite remains. They are the first representatives of the arachnid order Trigonotarbida to be found in Kansas. The specimens are referred to the genus Anthracomartus but are not identified to species pending revision of the American anthracomartids.

Description of a new species of crab, Ekalakia exophthalmops, brings to two the number of species within this Late Cretaceous genus from the upper mid-west in North America. Discovery of eyes and orbital structures in both species permits placement of the genus within the superfamily Glaessneropsoidea Patrulius, 1959 and family Glaessneropsidae Patrulius, 1959, extending the range of those taxa from the Late Jurassic into the Late Cretaceous. The extraordinarily large eyes relative to body size suggests that the Jurassic reef-dwelling crabs were adapted for a cryptic lifestyle which preadapted them for the deep-water, dysphotic, level-bottom habitat occupied by the Cretaceous descendants.