A bone bed in the middle part of the Javelina Formation (Maastrichtian) in Texas yielded parts of about 37 identifiable ceratopsid dinosaur bones, mostly appendicular and limb girdle elements belonging to one juvenile and two adult individuals of Torosaurus cf. utahensis. The bone bed is a lag assemblage comprising large immobile parts of the skeletons accumulated in an abandoned stream channel. In general form and proportions the postcranial bones are similar to those in Pentaceratops sternbergi and are not as robust as those in Torosaurus latus or Triceratops horridus. A few cranial elements are preserved, including parts of a parietal, squamosal, maxilla, and two dentaries. The form of the parietal fragment is comparable to that of a more nearly complete specimen of Torosaurus cf. utahensis collected nearby at about the same stratigraphic level. The bone bed material provides a basis for the first skeletal reconstruction of this enigmatic horned dinosaur. Most characters used in diagnoses of T. utahensis and T. latus are inadequate. Only the raised bar along the squamosal/parietal suture, present in T. latus; and the midline epiparietal, absent in T. latus, may discriminate the two species.

Based on a thorough examination of field and museum Climactichnites specimens, two species of this trace are recognized, each representing a unique behavioral variant produced by a soft-bodied animal in Late Cambrian intertidal environments. C. wilsoni represents surface-produced trails, whereas C. youngi is re-erected for burrows produced below the surface. Burrowing behavior is supported by: 1) the presence of C. youngi within, rather than on, the surface of beds; 2) the orientation of some burrows inclined to bedding; and 3) the occasional presence of distinct burrow fills. Burrows can also be distinguished morphologically from surface traces by the absence of lateral ridges and the presence of fine, mm-scale striations or grooves superimposed on the transverse bars and furrows. Burrowing behavior for the Climactichnites trailmaker was previously unknown and thus represents a new, although not entirely unexpected, behavior for this mollusk or mollusk-like animal. The body impression of the sedentary animal is removed to Musculopodus sedentarius n. igen. and isp. In the future, Musculopodus may be expanded to include the resting traces of other soft-bodied animals known from the fossil record. Currently, Climactichnites is known only from very shallow to emergent strata of North America; reports of this fossil in other parts of the world are misidentified trails produced by other animals.

The phylogenetic relationships of Paleozoic blastozoan echinoderms are poorly understood and many of the traditionally ascribed groups are likely polyphyletic. Diploporitans, those blastozoans with double pore (diplopore) respiratory structures, have never been placed within a rigorous phylogenetic framework, and their highly variable morphologies suggest that they do not represent a natural clade. A maximum parsimony phylogenetic analysis, spanning a wide range of diploporitan and related taxa, indicates that diplopore-bearing blastozoans are a polyphyletic grouping and, consequently, that diplopore respiratory structures have evolved more than once within the echinoderms. Constraint analyses indicate that a single diplopore-bearing clade bearing the traditionally defined Glyptosphaeritida, Sphaeronitida, Asteroblastida is less parsimonious than multiple diplopore-bearing clades inferred by the unconstrained analysis.

The Plum Brook Shale of north-central Ohio lies disconformably between the Eifelian (lower Middle Devonian) Delaware Limestone and the middle Givetian (upper Middle Devonian) Prout Dolomite. Its diverse conodont fauna indicates that it represents a transgression into the area in earliest Givetian time accompanied by the products of a notable adaptive radiation within two lineages of Icriodus. One of these (I. expansus Group) includes I. expansus, I. arkonensis and I. brevis, and complete intergradation of forms suggests that the group at this level involves conspecific ecotypes. A more extensive radiation involved descendants of I. regularicrescens (I. regularicrescens Group), including three new species, I. eriensis, I. janeae and I. ohioensis. Other representatives of this lineage occur here as well as in strata of comparable age in the type region of the Givet Limestone as described by Bultynck (1987). A third lineage is represented by I. excavatus in both areas, but evidence of radiation within this branch is limited to the Givet Limestone. Remarkable diversity also occurs among forms considered herein to involve Polygnathus pseudofoliatus and its descendants. The existence of intermediate forms and shared characteristics between and among the various species, including some that first appeared well before the end of the Eifelian, implies that they may be conspecific ecotypic variants at this level. New morphotypes within this group are treated informally. The greatest overall diversity occurs just above the basal Plum Brook, in strata interpreted to reflect inner-sublittoral conditions. The entire Plum Brook belongs to the upper ensensis Zone. A considerable part of the type Givetian placed in the Lower varcus Subzone by Bultynck (1987) lies below the lowest occurrence of its index species (P. timorensis); it contains some of the species found in the Plum Brook, and much of this section may also belong to the ensensis Zone.

Five new species of Maurotarion Alberti, 1969 from the Silurian Lipeón Formation and Lower Devonian Talacasto Formation of Argentina are recognized. The comparisons with Bolivian and South African species support a Malvinokaffric clade based on librigenal synapomorphies, here erected as Maurotarion (Malvinotarion) new subgenus. The Malvinokaffric origin of the family would not be a migration from lower paleolatitudes but an Early Silurian stock of rare cosmopolitan ancestors which underwent a great Devonian radiation. Two lineages can be recognized within Malvinokaffric Maurotarion. The Silurian-Pragian dereimsi lineage is a plesiomorphic one resembling Silurian representatives and involves M. (Malvinotarion) dereimsi, M. (Malvinotarion) talacastoense new species, M. (Malvinotarion?) new species A, M. (Malvinotarion?) new species B, M. (Malvinotarion) sp., and eventually M. (Malvinotarion?) cf. dereimsi. The isaacsoni lineage ranges from the Lower Pragian to Eifelian exhibiting a defined morphologic trend in the librigena. This lineage comprises M. (Malvinotarion) isaacsoni, M. (Malvinotarion) sp. A from South Africa, M. (Malvinotarion) gaucho new species, M. (Malvinotarion) haudei new species and M. (Malvinotarion) legrandi. A Lochkovian diversification probably took place yet an adequate assessment remains difficult. In contrast, a great evolutionary burst is recognized during the Emsian and is related to Pragian-Emsian global relative sea level curves which are coincident with those proposed from Bolivian and Argentinian basins.

The order Asaphida has been characterized by the possession of a globular protaspis and a ventral median suture. the superfamily Dikelocephaloidea was included in the Asaphida, although there has been no reliable ontogenetic information for this superfamily, and thus whether dikelocephaloids had a protaspis of globular shape has remained unclear. the ontogenetic study of the dikelocephaloid trilobite, Asioptychaspis subglobosa, from Korea reveals that the protaspis of A. subglobosa is not of globular morphology but of general benthic adult-like morphology, heralding that the Dikelocephaloidea may not be closely related to other trilobite groups within the Order Asaphida. This protaspid morphology is clearly distinguished from the highly globular protaspis of the Remopleuridioidea, which has been considered the sister group to the Dikelocephaloidea. in addition, the ontogenetic development of the free cheeks shows that A. subglobosa possessed anteriorly yoked free cheeks during the early phase of development but formed a ventral median suture by splitting the yoked cheeks in the later phase of ontogeny. This contrasts with the previously suggested mode of ventral median suture formation of the Order Asaphida. This alternative mode of ventral median suture formation of A. subglobosa, along with non-asaphoid protaspid morphology, warrants removal of the Dikelocephaloidea from the current Order Asaphida. This study further demonstrates that the ventral median suture did not evolve only once in the evolutionary history of trilobites. With the addition of the mode here documented for Asioptychaspis, the ventral median suture is now known to have developed independently and in a different fashion at least three times in the history of Cambrian trilobites.

A new genus and three new species of echinoids occur in several horizons of an echinoderm Lagerstätten in the Winchell Formation of north-central Texas. This occurrence is dominated by several thousand specimens of Archaeocidaris brownwoodensis new species, a medium-sized archaeocidarid with long, triangular, ornate spines. Another rare archaeocidarid, Archaeocidaris apheles n. sp., is a small, smooth-spined species. The second most abundant echinoid is Elliptechinus kiwiaster n. gen. and sp., an unusual elliptical lepidocentrid, which extends the range of lepidocentrids into the Pennsylvanian (Late Carboniferous). A fourth echinoid, an unidentified echinocystitid, is known from one disarticulated specimen and appears to be mostly composed of ambulacral plates of varying shape and size.

Maastrichtian ammonites are described from two areas in Pakistan. The upper part of the lower unit of the Korara Shale in the southern Pab Range, Kirthar Province, southern Balochistan, is dated as Late Maastrichtian, based on the presence of Menuites fresvillensis (Seunes, 1890), which is accompanied by abundant Indoceras baluchistanense Noetling, 1897, common Baculites ambatryensis Collignon, 1971, and rarer Neophylloceras surya (Forbes, 1846), Gaudryceras kayei (Forbes, 1846), Anagaudryceras politissimum (Kossmat, 1895), Kitchinites spengleri n. sp., Pachydiscus (Pachydiscus) noetlingi n. sp., Libycoceras acutodorsatus (Noetling, 1897), and Diplomoceras cylindraceum (Defrance, 1816). A smaller assemblage from the Mughal Kot Formation near Kach, Suleman Province, northern Balochistan cannot be dated more precisely than Maastrichtian from the presence of Pachydiscus (Pachydiscus) neubergicus (Hauer, 1858), the first occurrence of which has been provisionally adopted by the Subcommission on Cretaceous Stratigraphy as marking the base of the Maastrichtian stage. It is associated with numerous Eubaculites binodosus (Noetling, 1897).

The Campanian rudist fauna identified from the localities Playa Panamá, Santa Rosa National Park, Colorado de Abangares, and Bolsón in Guanacaste Province, Costa Rica, is composed of the antillocaprinids Antillocaprina sp. aff. A. suboccidentalis Chubb, 1967, Antillocaprina sp. and Antillocaprinidae indet.; the multiple-fold hippuritids Barrettia monilifera Woodward, 1862, Parastroma trechmanni Chubb, 1967, and cf. Whitfieldiella gigas (Chubb, 1955); the plagioptychids Plagioptychus trechmanni Chubb, 1956, Plagioptychus sp. cf. P. zansi Chubb, 1956, Mitrocaprina costaricaensis new species, Mitrocaprina multicanaliculata Chubb, 1956, and Plagioptychidae indet.; and the radiolitids Radiolites sp. aff. R. multicostata (Adkins, 1930), Alencasterites new genus mooretownensis (Trechmann, 1924), Bournonia? tetrahedron (Chubb, 1967), Chiapasella sp., Guanacastea costaricaensis new genus new species, cf. Potosites sp. aff. P. tristantorresi Alencáster and Pons in Pons et al., 2010, and aff. Thyrastylon sp. Although some differences in rudist diversity and sedimentary setting were observed among localities, most species indicate the same age for all occurrences, which correspond to the Campanian, probably mid-Campanian. Radiolitid specimens appear better preserved than those of other taxa and are thus discussed more in detail. Both the number of radiolitid genera exclusively known from the New World, and reasonable doubts about the correct attribution of some New World species to Old World genera, indicate important differences between rudist faunas at both sides of the Atlantic (Mediterranean and American Tethys, respectively) during the Late Cretaceous.

Isolated spines and scales from acanthodian fishes are common elements in vertebrate assemblages from the Early Devonian (Emsian) of Arizona, Idaho, Nevada, Utah, and Wyoming. The material described here is from the Sevy Dolomite and lower Grassy Flat Member, Water Canyon Formation, and includes one partially articulated specimen plus isolated fin spines and dermal plates of a new ?climatiid Sevyacanthus elliotti n. gen. and sp.; spines and shoulder girdle elements of a ?climatiid Nodocosta denisoni n. sp.; dentigerous jawbones from at least two ischnacanthiform taxa Ischnacanthus sp. and Cacheacanthus utahensis n. gen. and sp.; fin spines from a ?diplacanthiform Bryantonchus peracutus n. gen.; and scales of Ptychodictyon americanum n. sp. Most of the species appear endemic, although some show a close relationship with older Euramerican taxa (Ischnacanthus, Climatiidae sensu stricto) and younger Baltic taxa (Ptychodictyon rimosum, Nodocosta pauli).

The Lower Pennsylvanian Hale Formation, which comprises the lower portion of the type Morrowan Series, in northwestern Arkansas, is subdivided into the Cane Hill and overlying Prairie Grove Members. The Cane Hill Member includes interbedded shale and sandstone with a basal conglomerate containing clasts reworked from underlying, truncated Mississippian formations. The Prairie Grove Member is highly variable, but includes sandy biosparite and calcareous sandstone. Highly fossiliferous pebble conglomerate and calcirudite lenses occur sporadically throughout the Hale Formation. Ammonoids and conodonts show that the Cane Hill-Prairie Grove boundary is unconformable.

Several thousand ammonoids collected from more than 100 localities in the Hale Formation show that four ammonoid zones and two subzones are recognizable in the Hale succession, and consequently in the redefined Halian Stage of the Morrowan Series. These are, in ascending order, the Retites semiretia, Quinnites henbesti, Arkanites relictus (including the Arkanites relictus relictus and overlying Cancelloceras huntsvillense Subzones) and Verneuilites pygmaeus Zones. Halian Stage ammonoids are known primarily from northern Arkansas, but an upper Arkanites relictus Zone (Cancelloceras huntsvillense Subzone) ammonoid assemblage occurs in the Primrose Member of the Golf Course Formation in south central Oklahoma.

Conodont-ammonoid associations in the Hale sequence provide a basis for integration of independently based zonal information. Rhachistognathus primus Zone conodonts occur in the Retites semiretia Zone; the Idiognathoides sinuatus Zone ranges through the Quinnites henbesti and Arkanites relictus relictus Subzone. The overlying Cancelloceras huntsvillense Subzone and Verneuilites pygmaeus Zone both contain conodonts of the Neognathodus symmetricus Zone.

The Hale ammonoid succession has few, if any, species in common with the type Namurian of Europe, but numerous genera are common to both sequences and the generic successions coincide and are equivalent in degree of development. The Retites semiretia Zone is equivalent to the Reticuloceras circumplicatile Zone (R1a); the Quinnites henbesti and lower Arkanites relictus Zones correspond to some portion of the R2b–R2c interval; and the upper Arkanites relictus Zone and the Verneuilites pygmaeus Zone correlate to Zone G1. The Retites semiretia Zone correlates to the lower Reticuloceras-Baschkortoceras Genozone (Nm2b1) of the upper Namurian in the south Urals; the Quinnites henbesti Zone is equivalent to some portion of the Nm2b2–3 intervals of this zone; the lower Arkanites relictus Zone is equivalent to the lower Bilinguites-Cancelloceras Genozone (Nm2c1) and the upper Arkanites relictus and Verneuilites pygmaeus Zones correspond to the uppermost interval (Nm2c2) in the south Urals sequence.

Systematic descriptions of biostratigraphically significant Halian taxa, including Reticuloceras tiro Gordon, R. wainwrighti Quinn, Retites semiretia McCaleb, Arkanites relictus relictus (Quinn, McCaleb, and Webb), A. relictus redivivus n.subsp., Quinnites n.gen. (type species Q. henbesti (Gordon)), Q. textum (Gordon), Bilinguites eliasi n.sp., Cancelloceras huntsvillense n.sp., and Verneuilites pygmaeus (Mather) are also presented.

Study of abundant well-preserved specimens of cyrtospiriferid brachiopods from early Famennian triangularis Zone shelf deposits from South China shows that none of them can be attributed to the genera Cyrtospirifer Nalivkin in Fredericks, 1924, or Tenticospirifer Tien, 1938, as previously assigned. Some of these forms are reassigned to the new genus Plicapustula, with Spirifer (Sinospirifer) gortanioides Grabau, 1931 serving as the type species. Restudy of the Upper Devonian cyrtospiriferids of North America and South China indicates that genera of the subfamily Cyrtospiriferinae all developed a delthyrial covering usually composed of two or more thin plates referred to as a composite pseudodeltidium. the delthyrial covering of Cyrtiopsis Grabau, 1923 and other genera of the subfamily Cyrtiopsinae is a convex pseudodeltidium. the lack of a pedicle foramen penetrating the pseudodeltidia of Frasnian Cyrtospirifer indicates that most species had an atrophied pedicle. the pseudodeltidia of most early Famennian cyrtospiriferids are perforated by a pedicle tube or a central hypothyrid foramen as in Sinospirifer Grabau, 1931, or a hypothyrid-to-submesothyrid foramen as in Lamarckispirifer Gatinaud, 1949 and Plicapustula n. gen. the orientation and concavity of the interarea, used with other shell characteristics, are useful characters in species-level taxonomy of Famennian cyrtospiriferids.

Four major types of radial micro-ornament characterize Late Devonian species of Cyrtospirifer and other genera of the Cyrtospiriferinae. These are 1) the verneuili type, consisting of microspines arising from the shell surface with spine bases extending into the primary shell layer, with radial capillae; 2) the whitneyi-subextensus type with small pustules both in the grooves and on the plications; 3) the subarchiaci type characterized by pustules only on plications; and 4) the hayasakai type with coarse elongated pustules on plications and capillae in grooves. There is a notable increase in complexity of the medial plication patterns of shells of Late Devonian cyrtospiriferinids. Simple sinal plication patterns characterize shells of Frasnian species of Cyrtospirifer and related genera, whereas most early Famennian cyrtospiriferinids developed complex patterns. We have documented three variations in the structure of the cardinal processes of the Late Devonian cyrtospiriferids. These consist of 1) unsupported; 2) supported by callus (secondary shell material) from below; or 3) supported by a median septum.

In Hunan-South China, cyrtospiriferid diversity was low in the late Frasnian, but a postextinction radiation of cyrtospiriferids in the very early Famennian resulted in the evolution of numerous new genera within the interval of the undifferentiated triangularis Zone shortly after the Frasnian–Famennian (F–F) mass extinction. Cyrtospiriferid brachiopods of the subfamilies Cyrtospiriferinae and Cyrtiopsinae are important elements of the early Famennian post-extinction survivor and recovery faunas that migrated and radiated rapidly to occupy niches vacated by extinct clades of late Frasnian brachiopods.

Five new species of the highly successful reef-building coral genus Acropora are described from Eocene locations in England and France (Acropora britannica, A. alvarezi, A. wilsonae, A. bartonensis, and A. proteacea) and additional records are given for six fossil species (A. deformis, A. anglica, A. solanderi, A. roemeri, A. lavandulina, and A. ornata), based on re-examination of material in the collections of the Natural History Museum, London. Specimens came from the Lutetian (49.0 to 41.3 Ma) of France, Bartonian (41.4 to 37.0 Ma) of England and France and Priabonian (36.0-34.2 Ma) of England. Included are the earliest record of a species with tabular or plate-like colonies similar to those in the modern “hyacinthus” species group (A. proteacea n. sp.) and the earliest records of simple hispidose forms (A. bartonensis n. sp. and A. roemeri), similar to those in the modern “florida” species group. The Priabonian material from southern England (A. brittanica n. sp. and A. anglica) shows the earliest occurrence of two sturdy species groups, the “humilis II” and “robusta” groups respectively, which now occur together on reef fronts throughout the modern Indo-Pacific. The new descriptions and records contribute to evidence that the genus diversified rapidly after its appearance in the fossil record. This diversification may have contributed to the rapid speciation and dispersal, observed in this genus during the Neogene, culminating in its extraordinary dominance of modern Indo-Pacific reefs.

The earliest endosymbiotic tubeworms have been discovered within skeletons of the tabulate coral Heliolites sp. from the Silurian (Ludlow) of Podolia, Ukraine. The new tubeworm species has a maximum diameter about 1 mm, a slightly conical tube, a smooth lumen in the tube and a lamellar wall structure. The tube wall is 0.05-0.10 mm thick. The new endosymbiotic tubeworm Coralloconchus bragensis n. gen. and sp. shares zoological affinities with the tentaculitids (incertae sedis) and is assigned to the Family Cornulitidae (Tentaculita, Cornulitida).

Acid processing allowed systematic identification of 458 Upper Triassic silicified scleractinian corals (20 genera, 47 species) from the Alexander terrane (southeast Alaska) and Wrangellia (Wrangell Mountains, southern Alaska and Vancouver Island, Canada). Coral faunas, here presented, show taxonomic affinity with coeval collections from other Cordilleran terranes, specifically the Wallowa terrane (northeastern Oregon and Idaho) and Peru (South America) as well as the distant Tethys region. Genera from the Alexander terrane include: Kompsasteria Roniewicz, Gablonzeria Cuif, Cuifia Melnikova, Paracuifia Melnikova, Distichophyllia Cuif, Retiophyllia Cuif, Kuhnastraea Cuif, Margarosmilia Volz, Distichomeandra Cuif, Astraeomorpha Reuss, Pamiroseris Melnikova, Crassistella Roniewicz, Stylophyllum Frech, and Meandrostylis Frech. Genera from Wrangellia include: Gablonzeria Cuif, Distichophyllia Cuif, Retiophyllia Cuif, Kuhnastraea Cuif, Margarosmilia Volz, Distichomeandra Cuif, Astraeomorpha Reuss, Parastraeomorpha Roniewicz, Chondrocoenia Roniewicz, Pamiroseris Melnikova, Crassistella Roniewicz, Ampakabastraea? Alloiteau, Recticostastraea Stanley and Whalen, Meandrostylis Frech, Anthostylis Roniewicz, and the new genus Campesteria n. gen. New species include: Gablonzeria grandiosa n. sp., Paracuifia smithi n. sp., Paracuifia jennieae n. sp., P. anomala n. sp., Retiophyllia dendriformis n. sp., R. obtusa n. sp., and Campesteria prolixia n. sp.

We present new records of chondrichthyans recovered from strata of Maastrichtian age of the López de Bertodano Formation, Seymour (=Marambio) Island, and from levels of latest Campanian age of the Santa Marta Formation, James Ross Island, both located in the eastern Antarctic Peninsula. The material from Marambio Island comprises an associated assemblage with the first records of an indeterminate odontaspidid different from Odontaspis, as well as the genera Pristiophorus, Squatina, Paraorthacodus, and the species Chlamydoselachus tatere from the López de Bertodano Formation. Also, the studied section provides a well-constrained age for several taxa already recognized in the López de Bertodano Formation only by scattered samples of Maastrichtian age for the first time. The assemblage from Marambio Island is representative of one of the latest environmental conditions during the end of the Cretaceous in the coastal seas of the Larsen Basin before major changes that began after the K/P boundary. In addition, the finds from James Ross Island comprise the southernmost records of the neoselachians Cretalamna sp., Centrophoroides sp., as well as the holocephalans Callorhinchus sp. and an indeterminate rhinochimaerid, extending the occurrence of some of these taxa into the late Campanian, being their oldest record of the Weddellian Biogeographic Province.

Bituminous limestone of the Ediacaran Shibantan Member of the Dengying Formation (551–539 Ma) in the Yangtze Gorges area contains a rare carbonate-hosted Ediacara-type macrofossil assemblage. This assemblage is dominated by the tubular fossil Wutubus Chen et al., 2014 and discoidal fossils, e.g., Hiemalora Fedonkin, 1982 and Aspidella Billings, 1872, but frondose organisms such as Charnia Ford, 1958, Rangea Gürich, 1929, and Arborea Glaessner and Wade, 1966 are also present. Herein, we report four species of Arborea from the Shibantan assemblage, including the type species Arborea arborea (Glaessner in Glaessner and Daily, 1959) Glaessner and Wade, 1966, Arborea denticulata new species, and two unnamed species, Arborea sp. A and Arborea sp. B. Arborea arborea is the most abundant frond in the Shibantan assemblage. Arborea denticulata n. sp. resembles Arborea arborea in general morphology but differs in its fewer primary branches and lower length/width ratio of primary branches. Arborea sp. A and Arborea sp. B are fronds with a Hiemalora-type basal attachment. Sealing by microbial mats and authigenic cementation may have played an important role in the preservation of Arborea in the Shibantan assemblage. The Shibantan material of Arborea extends the stratigraphic, ecological, and taphonomic ranges of this genus.

UUID: http://zoobank.org/554f21da-5f09-4891-9deb-cbc00c41e5f1

The trilobite Reedops is documented from strata probably corresponding to the middle part of the Talacasto Formation in the Sierra de las Minitas, at the northernmost extent of the Precordillera in La Rioja Province, northwestern Argentina. The specimens resemble the type species of the genus, R. bronni, indicating a Pragian (Early Devonian) age for the strata, and suggesting the occurrence at this time of faunal exchange between the Old World Realm, particularly the Bohemian area, and the Malvinokaffric Realm. The taxon represents the first Early Devonian macrofaunal element in the Malvinokaffric Realm with global biostratigraphical significance.

Agglutinated siliceous foraminifera occur in the Middle Ordovician (Blackriveran) Mifflin Formation of the Platteville Group in northern Illinois. The fauna consists of globular saccamminids and a new form Reophax blackriveranus n. sp. which records the oldest validated representative of this genus. This marks the earliest known occurrence of agglutinated foraminifera with multichambered uniserial tests of progressively expanding chambers from the proloculus to the aperture. This early innovation of test morphology was probably developed to control unfavorable changes in the water chemistry of the environment.

Mifflin lithofacies consist of light gray, thin, wavy-bedded, lithographic limestone and fine-grained dolomite with green shale interbeds, thin calcarenite layers with graded bedding, a K-bentonite ash layer and hardground corrosion bedding surfaces. Mifflin biofacies include the foraminiferan fauna, brachiopods and molluscan shelly faunas, bryozoans, trilobites, ostracodes, echinoderms, solitary corals, conodonts, chitinozoans, scolecodonts, sponges and trace fossils particularly Chondrites.

The Mifflin strata were deposited on an exceedingly gentle slope off the Pecatonica carbonate platform which flanked the Wisconsin Arch. Thin Mifflin clinothem limestone beds wedge out into shales in the moderately deep (<200 m) aerobic starved basin in eastern Iowa. This occurred in south tropical seas during a eustatic rise in sealevel and major marine transgression. Reophax is associated with saccamminids in the benthos of the marine upper foreslope. Apparently slope-dwelling Reophax foraminifera of the Ordovician were displaced downslope into the basin by the rapid development and expansion of hyperamminids which occupy the lower and middle foreslope in the Mississippian.

Mytiloides hattini, a new species of inoceramid bivalve from the basal Turonian (Upper Cretaceous), is described and its stratigraphic importance discussed. This inoceramid is particularly significant because its first occurrence can be used as a marker for the base of the Turonian in strata that typically contain no ammonites and few other taxa. The lowest occurrence of Mytiloides hattini is characterized by abundant specimens over wide regions of the Western Interior of North America; this species also apparently occurs in the lowest Turonian strata of western Europe. The typical absence of ammonites in this stratigraphic interval potentially makes the first occurrence of Mytiloides hattini an important fossil for regional and intercontinental correlation of the Cenomanian–Turonian boundary.