Equivalent Beds Research Articles

A fresh look on the morphology of Azaniadendron Rayner: a ligulate lycopsid from the Permian of Gondwana

The monotypic Azaniadendron fertile Rayner, a lycopsid from the Guadalupian of Gondwana, is investigated providing new data on the morphology of its leaf cushions and their variation in shape. Evidence for a ligule is presented for the first time, elucidating, at least for this genus, a dilemma about the presence of this structure in lycopsids from the Permian Glossopteris flora. New data on its fertile axes question the assumption that the taxon produced true cones. We hypothesise that the genus belong to the Isoetales. Unequivocal evidence of the taxon is so far known only from the South African Vryheid Formation and its equivalent beds.

The Osteology of Haya griva (Dinosauria: Ornithischia) from the Late Cretaceous of Mongolia

Haya griva is an early-diverging neornithischian (“hypsilophodontid”) dinosaur known from several well-preserved skulls and articulated postcranial skeletons, in addition to dozens of partial or isolated finds from the Upper Cretaceous Khugenetslavkant and Zos Canyon localities (Javkhlant Formation and equivalent beds) in the Gobi Desert of Mongolia. Collectively, nearly the entire skeletal anatomy of Haya is known, including partial growth series of skulls and femora. Detailed description and comparisons with other ornithischians, including novel anatomical information about the palate and braincase gleaned through high-resolution x-ray microcomputed tomography, reveals a wealth of osteological data for understanding the growth and relationships of this key taxon. Though the Haya specimens span a wide size range, bone histology reveals that all are likely perinatal to subadult individuals, with specimens of intermediate age the most common, and skeletally mature specimens absent. Phylogenetic analyses place Haya as one of the few Asian members of Thescelosauridae, an important noncerapodan neornithischian group of the Late Cretaceous.

Two New Cassis (Gastropoda: Cassidae) and a New Malea (Gastropoda: Tonnidae) from the Pliocene and Pleistocene Beds of Southern Florida

Two new fossil Helmet Shells of the genus Cassis Scopoli, 1777 (Cassidae) and a new fossil Grinning Tun Shell of the genus Malea Valenciennes, 1832 (Tonnidae) are described from the Pliocene and Pleistocene fossil beds of southern Florida. The new Helmet Shells, Cassis rasae n. sp. and Cassis viliusi n. sp., were both collected in the rich fossil beds of the Holey Land Member of the Bermont Formation (Calabrian Stage, Early Pleistocene) and the new Grinning Tun, Malea hyaducki n. sp., was collected in the Fruitville Member (Kissimmee River Valley equivalent beds) of the Tamiami Formation (late Piacenzian Stage of the Pliocene). The discovery of two new large Helmet Shells in the Holey Land Member demonstrates that four species of Cassis are present in the Bermont Formation, making this the single largest fossil Cassis fauna found anywhere on Earth. The new Grinning Tun represents the oldest-known Malea found in Florida, and is the direct ancestor of the Gelasian Pleistocene Malea springi (Caloosahatchee Formation) and the Calabrian Pleistocene Malea petiti (Bermont Formation).

New sauces produced by koji fermentation of kamaboko show acceptable sensory characteristics, improved antioxidant activities, and high angiotensin-converting enzyme inhibition

In our previous study, kamaboko was fermented in koji to prolong its shelf life and to increase its health-promoting effects. After fermentation, the texture of the kamaboko became cheese- or tofuyo-like. In the present study, sauces were produced by the fermentation of kamaboko in fermentation beds of wheat (WS), rice (RS), brown rice (BS), or soybean koji (SS), and their sensory qualities examined. WS, RS and BS had similar qualities to commercial oyster sauce. Fried cabbage with RS had significantly better overall acceptance than fried cabbage with oyster sauce. SS had significantly higher ash, protein and fat contents, and significantly lower carbohydrate contents than WS, RS, and BS. Free amino acid contents increased following fermentation for all sauces, and were highest in SS. The sugar contents of WS, RS, and BS were significantly higher than that of SS. SS had the highest phenolic content followed by BS, WS and RS. Antioxidant activity and angiotensin-converting enzyme (ACE) inhibition were highest in SS. All the new sauces had significantly higher free amino acid contents than the equivalent fermentation beds without kamaboko.

Would the United States Have Had Too Few Beds for Universal Emergency Care in the Event of a More Widespread Covid-19 Epidemic?

(1) Background: To evaluate the level of hospital bed numbers in U.S. states relative to other countries using a new method for evaluating bed numbers, and to determine if this is sufficient for universal health care during a major Covid-19 epidemic in all states (2) Methods: Hospital bed numbers in each state were compared using a new international comparison methodology. Covid-19 deaths per 100 hospital beds were used as a proxy for bed capacity pressures. (3) Results: Hospital bed numbers show large variation between U.S. states and half of the states have equivalent beds to those in developing countries. Relatively low population density in over half of US states appeared to have limited the spread of Covid-19 thus averting a potential major hospital capacity crisis. (4) Conclusions: Many U.S. states had too few beds to cope with a major Covid-19 epidemic, but this was averted by low population density in many states, which seemed to limit the spread of the virus.

An extensive K-bentonite as an indicator of a super-eruption in northern Iberia 477 My ago

Zircon and monazite ID-TIMS U-Pb dating of four Lower Ordovician altered ash-fall tuff beds (K-Bentonites) in NW Iberia provided coetaneous ages of 477.5±1, 477±1.3 Ma, 477.2±1.1 Ma and 477.3±1 Ma, with a pooled concordia age of 477.2±0.74 Ma. A conservative estimation of the volume and mass of the studied K-bentonite beds (using data from the Cantabrian Zone) returns a minimum volume for the preserved deposits of ca. 37.5 km3 (Volcanic Explosivity Index - VEI = 6, Colossal). When considering other putative equivalent beds in other parts of Iberia and neighbouring realms the volume of ejecta associated to this event would make it reach the Supervolcanic-Apocalyptic status (VEI=8, >1000 km3). Contrary to most cases of this kind of gargantuan eruption events, the studied magmatic event took place in relation to continental margin extension and thinning and not to plate convergence. We speculate that a geochronologically coincident large caldera event observed in the geological record of NW Iberia could be ground zero of this super-eruption.

Late Cretaceous sauropod tooth morphotypes may provide supporting evidence for faunal connections between North Africa and Southern Europe

The Cretaceous Kem Kem beds of Morocco and equivalent beds in Algeria have produced a rich fossil assemblage, yielding, amongst others, isolated sauropod teeth, which can be used in species diversity studies. These Albian-Cenomanian (∼113–93.9 Ma) strata rarely yield sauropod body fossils, therefore, isolated teeth can help to elucidate the faunal assemblages from North Africa, and their relations with those of contemporaneous beds and geographically close assemblages. Eighteen isolated sauropod teeth from three localities (Erfoud and Taouz, Morocco, and Algeria) are studied here, to assess whether the teeth can be ascribed to a specific clade, and whether different tooth morphotypes can be found in the samples. Two general morphotypes are found, based on enamel wrinkling and general tooth morphology. Morphotype I, with mainly rugose enamel wrinkling, pronounced carinae, lemon-shaped to (sub)cylindrical cross-section and mesiodistal tapering towards an apical tip, shows affinities to titanosauriforms and titanosaurs. Morphotype II, characterized by more smooth enamel, cylindrical cross-section, rectangular teeth with no apical tapering and both labial and lingual wear facets, shows similarities to rebbachisaurids. Moreover, similarities are found between these northwest African tooth morphotypes, and tooth morphotypes from titanosaurs and rebbachisaurids from both contemporaneous finds from north and central Africa, as well as from the latest Cretaceous (Campanian–Maastrichtian, 83.6 Ma–66.0 Ma) of the Ibero-Armorican Island. These results support previous hypotheses from earlier studies on faunal exchange and continental connections between North Africa and Southern Europe in the Cretaceous.

Emsian (Early Devonian) Yujiang Event in South China

The Yujiang Event is reported here as a newly recognized event that occurred during the deposition of the Early Devonian Yukiang Formation in Liujing, Guangxi, and its equivalents in South China. The first episode of the Yujiang Event is characterized by the extinction of biostrome that is constructed mainly by colonies of rugose coral, tabulatimorph coral and bryozoan as well as the extinction of evolved biota including some brachiopods, bivalves, etc. The age of the first episode of the Yujiang Event dated by conodonts is at the beginning or the lower part of the Polygnathus nothoperbonus Zone. The main episode of Yujiang Event is evidenced by the extinction of the Rostrospirifer tonkinensis Fauna (sensu lato) at the top of Yukiang Formation and by the sudden occurrences of the dolostones and dolomitic limestone of the overlying Moding Formation. At the basal part of the Moding Formation, the new finding of conodont Polygnathus nothoperbonus and dacryconarids Nowakia (N.) barrandei indicates that this episode of Yujiang Event may occur in the upper part of the Polygnathus nothoperbonus Zone. Overlying the Yukiang Formation and its equivalent beds, various lithic deposits correspondingly yielding different biota can be seen widely in many localities and sections in South China and northern Vietnam. Therefore, the Yujiang Event can be recognized not only as a biotic extinction event, but also as a geological event.

Was there a super-eruption on the Gondwanan coast 477 Ma ago?

Precise zircon and monazite ID-TIMS U–Pb dating of three Lower Ordovician altered ash-fall tuff beds (K-bentonites) in the Cantabrian Zone of NW Iberia yielded coeval ages together with an equivalent previously studied sample (477.5±1 (Gutierrez-Alonso et al., 2007)), of 477±1.3Ma, 477.2±1.1Ma and 477.3±1Ma, with a pooled concordia age (all analyses in the four samples) of 477.2±0.74Ma. A conservative estimation of the volume and mass of the studied K-bentonite beds (using exclusively the CZ data) yields a volume for the preserved deposits of ca. 37.5km3 (Volcanic Explosivity Index — VEI=6, Colossal). When considering other putative equivalent beds in Iberia and neighboring realms (i.e. Armorica, Sardinia) the volume of ejecta associated to this event would make it reach the Supervolcanic–Apocalyptic status (VEI=8, >1000km3). At variance with most known cases of this kind of gigantic eruption events, geological observations indicate that the studied magmatic event was related to continental margin extension and thinning and not to plate convergence. We speculate that a geochronologically equivalent large caldera event recognized in the geological record of NW Iberia could be ground zero of this super-eruption.

A New Brachylophosaurin Hadrosaur (Dinosauria: Ornithischia) with an Intermediate Nasal Crest from the Campanian Judith River Formation of Northcentral Montana.

BackgroundBrachylophosaurini is a clade of hadrosaurine dinosaurs currently known from the Campanian (Late Cretaceous) of North America. Its members include: Acristavus gagslarsoni, which lacks a nasal crest; Brachylophosaurus canadensis, which possesses a flat paddle-shaped nasal crest projecting posteriorly over the dorsal skull roof; and Maiasaura peeblesorum, which possesses a dorsally-projecting nasofrontal crest. Acristavus, from the lower Two Medicine Formation of Montana (~81–80 Ma), is hypothesized to be the ancestral member of the clade. Brachylophosaurus specimens are from the middle Oldman Formation of Alberta and equivalent beds in the Judith River Formation of Montana; the upper Oldman Formation is dated 77.8 Ma.Methodology/Principal FindingsA new brachylophosaurin hadrosaur, Probrachylophosaurus bergei (gen. et sp. nov.) is described and phylogenetically analyzed based on the skull and postcranium of a large individual from the Judith River Formation of northcentral Montana (79.8–79.5 Ma); the horizon is equivalent to the lower Oldman Formation of Alberta. Cranial morphology of Probrachylophosaurus, most notably the nasal crest, is intermediate between Acristavus and Brachylophosaurus. In Brachylophosaurus, the nasal crest lengthens and flattens ontogenetically, covering the supratemporal fenestrae in large adults. The smaller nasal crest of Probrachylophosaurus is strongly triangular in cross section and only minimally overhangs the supratemporal fenestrae, similar to an ontogenetically earlier stage of Brachylophosaurus. Sutural fusion and tibial osteohistology reveal that the holotype of Probrachylophosaurus was relatively more mature than a similarly large Brachylophosaurus specimen; thus, Probrachylophosaurus is not simply an immature Brachylophosaurus.Conclusions/SignificanceThe small triangular posteriorly oriented nasal crest of Probrachylophosaurus is proposed to represent a transitional nasal morphology between that of a non-crested ancestor such as Acristavus and the large flat posteriorly oriented nasal crest of adult Brachylophosaurus. Because Probrachylophosaurus is stratigraphically and morphologically intermediate between these taxa, Probrachylophosaurus is hypothesized to be an intermediate member of the Acristavus-Brachylophosaurus evolutionary lineage.

The critical scale of small-scale spatial variation in ecological patterns and processes in intertidal macrobenthic seagrass assemblages

Earlier work on benthic faunal assemblages in intertidal seagrass beds has shown maximal structural variation at spatial scales <150 m. To examine more closely spatial variation of species assemblages within this range, numbers of target taxa in the beds on North Stradbroke Island, Moreton Bay, Australia, were sampled at nested spatial scales of 0.5, 5, 30 and 90 m at two localities 900 m apart. Variance components were largest at the smallest scales, that at 0.5 m comprising 55% of the total and that at 5 m 13%. Individual species were patchily dispersed and their assemblages were randomly structured at all studied spatial scales. Although assemblage composition differed significantly between the two localities, overall faunal abundance and species richness were relatively uniform across the whole study area. These seagrass beds show little turn-over of dominant species and little evidence of niche partitioning through space over scales of <1 km. In this they contrast markedly with the equivalent intertidal dwarf-eelgrass beds of Knysna in South Africa that form a high turn-over, strongly structured, deterministic system.

Spatial niche partitioning in dinosaurs from the latest cretaceous (Maastrichtian) of North America

We examine patterns of occurrence of associated dinosaur specimens (n = 343) from the North American Upper Cretaceous Hell Creek Formation and equivalent beds, by comparing their relative abundance in sandstone and mudstone. Ceratopsians preferentially occur in mudstone, whereas hadrosaurs and the small ornithopod Thescelosaurus show a strong association with sandstone. By contrast, the giant carnivore Tyrannosaurus rex shows no preferred association with either lithology. These lithologies are used as an indicator of environment of deposition, with sandstone generally representing river environments, and finer grained sediments typically representing floodplain environments. Given these patterns of occurrence, we argue that spatial niche partitioning helped reduce competition for resources between the herbivorous dinosaurs. Within coastal lowlands ceratopsians preferred habitats farther away from rivers, whereas hadrosaurs and Thescelosaurus preferred habitats in close proximity to rivers, and T. rex, the ecosystem's sole large carnivore, inhabited both palaeoenvironments. Spatial partitioning of the environment helps explain how several species of large herbivorous dinosaurs coexisted. This study emphasizes that different lithologies can preserve dramatically dissimilar vertebrate assemblages, even when deposited in close proximity and within a narrow window of time. The lithology in which fossils are preserved should be recorded as these data can provide unique insights into the palaeoecology of the animals they preserve.

Evidence for a cosmogenic origin of fired glaciofluvial beds in the northwestern Andes: Correlation with experimentally heated quartz and feldspar

Fired sediment, considered equivalent to the ‘Black Mat’ impact of 12.9 ka, has been located and analyzed in the Andes of northwestern Venezuela. The ‘Black Mat’ refers to possible fallout from the Encke Comet airburst presumed to have occurred over the Laurentide Ice Sheet, the impact spreading ejecta over large portions of North America and Europe, making it an interhemispheric event of considerable magnitude. These possible equivalent beds in the northern Andes, first considered to result from a lightning-induced conflagration adjacent to the retreating Late Wisconsinan (Mérida Glaciation) ice, are now known to have undergone intense heating upon impact to a temperature much higher than what would occur in a wet, first-stage, successional tundra. Analyses carried out by SEM and FESEM, in SE and BSE modes, show massive micro-disruption on grain surfaces, fractures diminishing with depth toward grain interiors and C welded onto quartz and plagioclase minerals. Bubbles on some grains, possibly the result of exclusion of water-of-crystallization, are seen on some samples, principally quartz. The presence of copious monazite in the carbonaceous coatings is considered part of the incoming ejecta, as it is not a common indicator mineral in the local lithology. Analysis by SEM and FESEM of quartz and plagioclase subjected experimentally to temperatures ranging from 500 to 900 °C shows that intense heating affects resident mineralogies to differing extents, with grain disruption more prevalent along cleavage planes deep into grain interiors. The intergrowth of carbonaceous “black mat” material with thermally disrupted and fragmented quartz and feldspar, a “welded” patina of 100–400 nm thickness could only occur with temperatures in excess of 900 °C, the event interpreted here to be of cosmogenic origin.

Reconciling discrepant chronologies for the geomagnetic excursion in the Mono Basin, California: Insights from new 40Ar/ 39Ar dating experiments and a revised relative paleointensity correlation

Lacustrine sediments of the Wilson Creek Formation in the Mono Basin, California, record a paleomagnetic field excursion constrained by 14C and 40Ar/ 39Ar geochronology to have occurred within the last 50 ka. However, 14C and 40Ar/ 39Ar ages are discordant, making it difficult to distinguish which of two possible excursions during this period, the Mono Lake or Laschamp, is recorded in the Mono Basin. New 40Ar/ 39Ar age determinations from sanidine, as well as the first biotite and obsidian ages, for three of the nineteen rhyolitic ashes intercalated with these sediments are presented and compared to previous 14C and 40Ar/ 39Ar data sets. Although the sanidine ages of the three ashes are stratigraphically consistent with each other and previously determined 40Ar/ 39Ar ages for other ashes in the Wilson Creek Formation, each is significantly older than 14C ages obtained from stratigraphically equivalent beds, relative paleointensity field correlations, oxygen isotope records, and glacial histories. These data indicate an absence of juvenile, eruptive crystals and most likely reflect the incorporation of crystals from older volcanic centers or underlying sediment. We examine the strengths and weaknesses of all available geochronologic data for the section exposed at Wilson Creek to arrive at an internally consistent set of age constraints. Using these constraints we propose two new relative paleointensity correlations for the section, both of which indicate that the excursion recorded in the Mono Basin occurred at ∼30–34 ka on the Greenland Ice Sheet Project 2 (GISP2) ice core time scale.

Computational analysis of transitional air flow through packed columns of spheres using the finite volume technique

We compare computational simulations of the flow of air through a packed column containing spherical particles with experimental and theoretical results for equivalent beds. The column contained 160 spherical particles at an aspect ratio N = 7.14 , and the experiments and simulations were carried out at particle Reynolds numbers of ( R e d P = 700 − 5000 ) . Experimental measurements were taken of the pressure drop across the column and compared with the correlation of Reichelt (1972) using the fitted coefficients of Eisfeld and Schnitzlein (2001). An equivalent computational domain was prepared using Monte Carlo packing, from which computational meshes were generated and analysed in detail. Computational fluid dynamics calculations of the air flow through the simulated bed was then performed using the finite volume technique. Results for pressure drop across the column were found to correlate strongly with the experimental data and the literature correlation. The flow structure through the bed was also analysed in detail.

A NEW BASAL CENTROSAURINE CERATOPSID FROM THE OLDMAN FORMATION, SOUTHEASTERN ALBERTA

Abstract A new centrosaurine ceratopsid, Albertaceratops nesmoi, is described from the lower Oldman Formation (Upper Cretaceous) of southern Alberta, and is based on a single, almost complete skull. Referred material is described from equivalent beds in the Judith River Formation of north-central Montana. A limited phylogenetic analysis of the Ceratopsidae places the new taxon as the basal member of the Centrosaurinae and indicates that robust, elongate postorbital horncores that form a synapomorphy of (Ceratopsidae + Zuniceratops) are also present in Centrosaurinae.

Magnetostratigraphy susceptibility of the Upper Ordovician Kope Formation, northern Kentucky

As a test of the utility of magnetic susceptibility (MS) measurements for correlation among lithified marine sequences, samples were collected from well-studied shale and limestone outcrops of the Upper Ordovician Kope Formation, northern Kentucky. The bulk (initial) low-field MS of these samples is compared among two litho- and biostratigraphically correlated sections containing the same beds. The results of this comparison demonstrated an excellent correlation among equivalent beds. Thermomagnetic susceptibility analysis supports previous XRD work indicating that illite is primary and is the main paramagnetic mineral responsible for the MS variations observed in this study. A composite of MS results for a sequence of 31 named shale–limestone couplets is used to build a composite section of Kope sequences for the area. These MS variations permit division of the various sections into a set of 28 MS cycles within the Kope Formation, covering ∼ 50 m of section. These cycles suggest a systematic control by climate on the influx of detrital material that formed these sedimentary sequences, and support other work indicating Kope climate cyclicity.

Radiobiological modelling of dose-gradient effects in low dose rate, high dose rate and pulsed brachytherapy

This paper presents a generalization of a previously published methodology which quantified the radiobiological consequences of dose-gradient effects in brachytherapy applications. The methodology uses the linear-quadratic (LQ) formulation to identify an equivalent biologically effective dose (BEDeq) which, if applied uniformly to a specified tissue volume, would produce the same net cell survival as that achieved by a given non-uniform brachytherapy application. Multiplying factors (MFs), which enable the equivalent BED for an enclosed volume to be estimated from the BED calculated at the dose reference surface, have been calculated and tabulated for both spherical and cylindrical geometries. The main types of brachytherapy (high dose rate (HDR), low dose rate (LDR) and pulsed (PB)) have been examined for a range of radiobiological parameters/dimensions. Equivalent BEDs are consistently higher than the BEDs calculated at the reference surface by an amount which depends on the treatment prescription (magnitude of the prescribed dose) at the reference point. MFs are closely related to the numerical BED values, irrespective of how the original BED was attained (e.g., via HDR, LDR or PB). Thus, an average MF can be used for a given prescribed BED as it will be largely independent of the assumed radiobiological parameters (radiosensitivity and α/β) and standardized look-up tables may be applicable to all types of brachytherapy treatment. This analysis opens the way to more systematic approaches for correlating physical and biological effects in several types of brachytherapy and for the improved quantitative assessment and ranking of clinical treatments which involve a brachytherapy component.

Correlation of the Lower Permian surface Saiwan Formation and subsurface Haushi limestone, Central Oman

ABSTRACT The palaeontology of the Saiwan Formation (Lower Permian) of the Al-Huqf outcrop area, Central Oman, has been the subject of significant study, but that of approximately equivalent beds in the subsurface (the Haushi limestone and ‘basal sandstones’ of the lower Gharif member) has been unknown until now. This has meant that the precise relationship between the surface and subsurface units has been poorly understood. A new subsurface brachiopod study has allowed a fourfold biozonation that correlates the surface Saiwan Formation with the subsurface Haushi limestone, implying that previous direct correlation of the Saiwan Formation with the lower Gharif member is not correct. Overall the brachiopod fauna of the subsurface is of lower diversity than that of the outcropping Saiwan Formation, suggesting deposition in quieter and deeper marine settings. The occurrence of a fusulinid assemblage with Pseudofusulina ex gr. karapetovi karapetovi Leven, the first such record in Gondwana, suggests a Sakmarian age for the Haushi limestone, and brachiopod data supports this determination. Subsurface Haushi limestone palynological assemblages, though diverse, are poorly preserved, and no palynomorphs have been recovered from equivalent surface outcrops. However, the distribution of autochthonous algal spores in three of the subsurface Haushi limestone sections suggest a local biozonation that is consistent with that indicated by brachiopods, while the terrestrially-sourced palynomorphs in the subsurface Haushi limestone sections indicate an OSPZ3c age. Surprisingly the sections contain no palynomorphs of unequivoval marine origin. Fusulinids indicate that a Sakmarian age for OSPZ3c is more likely than the Artinskian age suggested by previous palynological studies. The terrestrially sourced palynomorphs also suggest correlation of the carbonates of the Haushi limestone with the highest part of the clastic lower Gharif Member in South Oman, above the Ulanisphaeridium omanensis Biozone or Maximum Flooding Shale in that area. Using the new biozonation, the distribution of facies has been mapped for three time slices. This reveals an increase in carbonate deposition during the Sakmarian due to distancing and deepening of the terrigenous source, coupled with climatic warming, culminating with a regressive trend at the end of the cycle. A progressive increase in carbonate deposition is recorded westward into the basin.

An elasmobranch assemblage from the terrestrial-marine transitional Lethbridge Coal Zone (Dinosaur Park Formation: Upper Campanian), Alberta, Canada

The change in depositional environments observed in the Cretaceous (Upper Campanian) strata in the region of Dinosaur Provincial Park, Alberta, from the proximal coastal plain deposits of the Oldman Formation to the lowland coastal plain deposits of the Dinosaur Park Formation, reveals an associated change in faunal composition. An assemblage collected from a microvertebrate site in the paralic deposits of the Lethbridge Coal Zone (uppermost Dinosaur Park Formation) reflects an increasing marine influence. Elasmobranch (sharks and rays) remains are the most abundant, both in terms of number of overall taxa and number of elements, and they are the best-preserved specimens. However, several brackish-water-tolerant osteichthyan taxa, and four reptile taxa (two marine and two terrestrial), were also recovered, although they exhibited evidence of extensive taphonomic reworking.The elasmobranch fauna collected from the Dinosaur Park locality is uncommon for vertebrate microfossil assemblages in the Dinosaur Park Formation of Alberta and in equivalent beds in Montana. Seven of the 10 taxa collected from this site [Cretorectolobus olsoni Case, 1978; Eucrossorhinus microcuspidatus Case, 1978; Odontaspis aculeatus (Cappetta and Case, 1975); Archaeolamna kopingensis judithensis Siverson, 1992; Protoplatyrhina renae Case, 1978; Ischyrhiza mira Leidy, 1856; and Ptychotrygon blainensis Case, 1978] are recorded for the first time from the uppermost section of the Judith River Group in Alberta; Carcharias steineri (Case, 1987), represents the first occurrence within the upper Judith River Group from either Alberta or Montana.