Hall Lake Research Articles

A giant tyrannosaur from the Campanian–Maastrichtian of southern North America and the evolution of tyrannosaurid gigantism

Tyrannosaurid dinosaurs dominated as predators in the Late Cretaceous of Laurasia, culminating in the evolution of the giant Tyrannosaurus rex, both the last and largest tyrannosaurid. Where and when Tyrannosaurini (T. rex and kin) originated remains unclear. Competing hypotheses place tyrannosaurin origins in Asia, or western North America (Laramidia). We report a new tyrannosaurin, Tyrannosaurus mcraeensis, from the Campanian–Maastrichtian Hall Lake Formation of New Mexico, based on a fossil previously referred to T. rex. T. mcraeensis predates T. rex by ~ 6–7 million years, yet rivaled it in size. Phylogenetic analysis recovers T. mcraeensis as sister to T. rex and suggests Tyrannosaurini originated in southern Laramidia. Evolution of giant tyrannosaurs in southern North America, alongside giant ceratopsians, hadrosaurs, and titanosaurs suggests large-bodied dinosaurs evolved at low latitudes in North America.

Sierraceratops turneri, a new chasmosaurine ceratopsid from the Hall Lake Formation (Upper Cretaceous) of south-central New Mexico

The horned dinosaurs (Ceratopsidae) were a diverse family of herbivorous dinosaurs originating in the Late Cretaceous in western North America (Laramidia). As one of the most species-rich dinosaur groups, their diversity and distribution are important to understanding Cretaceous dinosaur evolution. Ceratopsids have previously been hypothesized to have high levels of endemism despite inhabiting a relatively small land mass with few barriers to dispersal. Here, we document a new chasmosaurine ceratopsid, Sierraceratops turneri gen. et sp. nov., from the Upper Cretaceous (uppermost Campanian–Maastrichtian) Hall Lake Formation of south-central New Mexico, consistent with the hypothesis that southern Laramidia supported an endemic dinosaur fauna. Sierraceratops is distinguished by its relatively short, robust, and mediolaterally compressed postorbital horns; a flattened medial ridge on the posterior end of the pterygoid; a jugal with pronounced anterior flanges; a long pyramid-shaped epijugal horncore; a D-shaped cross section of the median parietal bar; and a squamosal with a pointed tip and low episquamosal ossifications. Phylogenetic analysis recovers Sierraceratops as sister to Bravoceratops and Coahuilaceratops, part of a clade endemic to the southwestern United States and Mexico. Sierraceratops adds to the diversity and disparity of the Chasmosaurinae in the Late Cretaceous and provides additional evidence for Laramidian endemism. Together with Sierraceratops, the Hall Lake Formation dinosaur fauna suggests that the latest Cretaceous of southern Laramidia was characterized by endemic clades and distinct community structures.

Onset of the Laramide orogeny and associated magmatism in southern New Mexico based on U-Pb geochronology

The Laramide orogeny is a classic yet controversial mountain-building event that resulted, in the southwest United States, in uplifts, sedimentation, and magmatism that can be used to constrain the onset of this event in the region and expand our knowledge of Late Cretaceous to Paleogene tectonism. The McRae Formation marks the onset of deposition in the Laramide Love Ranch Basin, which was located to the northeast of the west-northwest-trending coeval Rio Grande uplift in south-central New Mexico, but its age is not well constrained. A previously published late Maastrichtian age for the McRae Formation was based on the presence of dinosaur bones in the upper of two members of the formation. We obtained new U-Pb dates from one dacite clast and three ash-fall tuffs from the lower Jose Creek Member and from one ash-fall tuff from the lower part of the overlying Hall Lake Member of the McRae Formation. The clast yielded a date of 75.0 ± 1.1 Ma, whereas the ages of the tuffs, in ascending stratigraphic order, are 74.9 ± 0.7 Ma, 74.7 ± 0.6 Ma, 75.2 ± 1.3 Ma, and 73.2 ± 0.7 Ma. These dates indicate that the onset of Laramide deposition in the Love Ranch Basin must have occurred earlier, in late Campanian time, similar to deposition in the Laramide Ringbone Basin in southwestern New Mexico. In addition, U-Pb zircon dates of 75.7 ± 1.3 Ma and 75.0 ± 2.8 Ma were obtained on the Twin Peaks stock and on a dacite sill, respectively, in the Burro Mountains of southwestern New Mexico. These dates are similar to those of other Laramide arc magmatic centers in southern New Mexico, which have a limited range of ages from 75 to 70 Ma, including the Hidalgo Formation in the Little Hatchet Mountains, the Silver City-Pinos Altos region, and the Copper Flat porphyry system. These new and previously published dates indicate that during the onset of Laramide deformation in southwestern and south-central New Mexico, the angle of subduction of the Farallon plate may have been steep enough to allow partial melting of an asthenospheric wedge, resulting in arc magmatism far inboard of the trench.

Back to the future: using palaeolimnology to infer long‐term changes in shallow lake food webs

Summary1. Shallow lakes are often cited as classic examples of systems that exhibit trophic cascades but, whilst they provide good model systems with which to test general ecological theory and to assess long‐term community change, their food web linkages have rarely been resolved, so changes associated with the structure and dynamics of the ecological network as a whole are still poorly understood.2. We sought to redress this, and to demonstrate the potential benefits of integrating palaeolimnological and contemporary data, by constructing highly resolved food webs and stable isotope derived measures of trophic interactions and niche space, for the extant communities of two shallow U.K. lakes from different positions along a gradient of eutrophication. The contemporary surface sediment cladoceran and submerged macrophyte assemblages in the less enriched site, Selbrigg Pond, matched the palaeolimnological assemblages of the more enriched site, Felbrigg Hall Lake, in its more pristine state during the 1920s. Thus, Selbrigg was a temporal analogue for Felbrigg, from which the consequences of long‐term eutrophication on food web structure could be inferred. These data represent the first steps towards reconstructing not only past assemblages (i.e. nodes within a food web), but also past interactions (i.e. links within a food web): a significant departure from much of the previous research in palaeolimnology.3. The more eutrophic food web had far fewer nodes and links, and thus a less reticulate network, than was the case for the more pristine system. In isotopic terms, there was vertical compression in δ15N range (NR) and subsequent increased overlap in isotopic niche space, indicating increased trophic redundancy within Felbrigg. This structural change, which was associated with a greater channelling of energy through a smaller number of nodes as alternative feeding pathways disappear, could lead to reduced dynamic stability, pushing the network towards further simplification. These changes reflected a general shift from a benthic‐dominated towards a more pelagic system, as the plant‐associated subweb eroded.4. Although these data are among the first of their kind, the palaeo‐analogue approach used here demonstrates the huge potential for applying food web theory to understand how and why these ecological networks change during eutrophication. Furthermore, because of the rich biological record preserved in their sediments, shallow lakes represent potentially important models for examining long‐term intergenerational dynamics, thereby providing a means by which models and data can be integrated on meaningful timescales – a goal that has long proved elusive in food web ecology.

Long‐term dynamics of submerged macrophytes and algae in a small and shallow, eutrophic lake: implications for the stability of macrophyte‐dominance

Summary1. Submerged macrophyte and phytoplankton components of eutrophic, shallow lakes have frequently undergone dynamic changes in composition and abundance with important consequences for lake functioning and stability. However, because of a paucity of long‐term survey data, we know little regarding the nature, direction and sequencing of such changes over decadal–centennial or longer timescales.2. To circumvent this problem, we analysed multiple (n = 5) chronologically correlated sediment cores for plant macro‐remains and a single core for pollen and diatoms from one small, shallow, English lake (Felbrigg Hall Lake, Norfolk, U.K.), documenting 250 years of change to macrophyte and algal communities.3. All five cores showed broadly similar stratigraphic changes in macrophyte remains with three distinct phases of macrophyte development: Myriophyllum–Chara–Potamogeton (c. pre‐1900), to Ceratophyllum–Chara–Potamogeton (c. 1900–1960) and finally to Zannichellia–Potamogeton (c. post‐1960). Macrophyte species richness declined from at least 10 species pre‐1900 to just four species at the present day. Additionally, in the final Zannichellia–Potamogeton phase, a directional shift between epi‐benthic and phytoplankton‐based primary production was indicated by the diatom data.4. Based on macrophyte–seasonality relationships established for the region, concomitant with the final shift to Zannichellia–Potamogeton, we infer a reduction in the seasonal duration of plant dominance (plant‐covered period). Furthermore, we hypothesise that this change in species composition resulted in a situation whereby macrophyte populations were seasonally ‘sandwiched’ between two phytoplankton peaks in spring and late summer as observed in the contemporary lake.5. We suggest that eutrophication‐induced reductions in macrophyte species richness, especially if the number of plant‐seasonal strategies is reduced, may constrict the plant growing season. In turn, this may render a shallow lake increasingly vulnerable to seasonal invasions of phytoplankton resulting in further species losses in the plant community. Thus, as part of a slow (over perhaps 10–100s of years) and self‐perpetuating process, macrophytes may be gradually pushed out by phytoplankton without the need for a perturbation as required in the alternative stable states model of plant loss.

Latest Cretaceous (Maastrichtian) aridity indicated by paleosols in the McRae Formation, south-central New Mexico

The McRae Formation in south-central New Mexico contains paleosols that indicate a significant increase in aridity occurred during the latest Cretaceous (late Maastrichtian). The McRae Formation is approximately 420 m thick and consists of interbedded fluvial channel sandstone and conglomerate, floodplain mudstone and fine sandstone, and siliceous ash-fall tuff. It has been divided into a lower Jose Creek Member and an upper Hall Lake Member. A Lancian dinosaur fauna is present in both members, indicating a late Maastrichtian age for the McRae Formation. Jose Creek paleosols are classified as argillisols and probably formed under humid to subhumid conditions. Paleosols in the Jose Creek member consist of A, ±E, and Bt horizons and are associated with numerous in situ petrified stumps, the largest of which is 1.7 m in diameter. The argillic B horizons (Bt) contain vertical clay-filled root traces, rhizoliths, blocky peds, embedded-grain argillans, and ped argillans. In contrast, paleosols in the Hall Lake Member are calcisols and vertic calcisols. These paleosols are characterized by Bw, Bt, Btk, Bk, and K horizons. The calcic horizons contain vertical calcite-filled tubules and carbonate nodules, in addition to calcans, spar coats, brecciated zones, alveolar-septal fabric and gypsum pseudomorphs. The vertic calcisols contain wedge-shaped peds and slickensides. The presence of calcic horizons in the Hall Lake Member suggest that the paleoclimate was significantly drier than during deposition of the Jose Creek Member. In addition, the vertic features indicate periods of wetting and desiccation (seasonality of precipitation?) during Hall Lake Time. Late Maastrichtian aridity, based on paleosols, has been interpreted for the Big Bend region of Texas, central Utah, and for Alberta, Canada, suggesting that the increase in aridity found in south-central New Mexico occurred throughout the Western Interior of North America.

The geochemical cycling of trace elements in a biogenic meromictic lake

The geochemical processes affecting the behavior and speciation of As, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn in Hall Lake, Washington, USA, are assessed by examining dissolved and acid soluble particulate profiles of the elements and utilizing results from thermodynamic calculations. The water column of this meromictic lake is highly stratified and contains distinctive oxic, suboxic, and anoxic layers. Changes in the redox state of the water column with depth affect the distribution of all the elements studied. Most noticeable are increases in dissolved Co, Cr, Fe, Mn, Ni, Pb, and Zn concentrations across the oxic-suboxic boundary, increases in dissolved As, Co, Cr, Fe, Mn, and V concentrations with depth in the anoxic layer, significant decreases in dissolved Cu, Ni, Pb, and Zn concentrations in the anoxic region below the sulfide maximum, and large increases in acid soluble particulate concentrations of As, Cr, Cu, Fe, Mo, Ni, Pb, V, and Zn in the anoxic zone below the sulfide maximum. Thermodynamic calculations for the anoxic region indicate that all redox sensitive elements exist in their reduced forms, the primary dissolved forms of Cu, Ni, Pb, and Zn are metal sulfide solution complexes, and solid sulfide phases of Cu, Fe, Mo, and Pb are supersaturated. Calculations using a vertical diffusion and reaction model indicate that the oxidation rate constant for Mn(II) in Hall Lake is estimated to be 0.006 d −1 and is at the lower end of the range of microbial oxidation rates observed in other natural systems. The main geochemical processes influencing the distribution and speciation of trace elements in Hall Lake appear to be transformations of dissolved elements between their oxidation states (As, Cr, Cu, Fe, Mn, V), cocycling of trace elements with Mn and Fe (As, Co, Cr, Cu, Mo, Ni, Pb, V, Zn), formation of soluble metal sulfide complexes (Co, Cu, Ni, Pb, Zn), sorption (As, Co, Cr, Ni, V), and precipitation (Cu, Fe, Mn, Mo, Pb, Zn).

Raised Marine Features, Radiocarbon Dates, and Sea Level Changes, Eastern Melville Peninsula, Arctic Canada

Radiocarbon dates from eastern Melville Peninsula indicate that deglaciation of western Foxe Basin occurred about 6900 years ago, although late ice persisted in an area northwest of Hall Lake and on the central plateau. Relative sea level was as high as 144 m above present at that time. Two new well-controlled sea level curves depict emergence as an exponential decay function. Marine limit elevations and nested curves indicate a major ice-loading centre in south-central Foxe Basin. These data and archaeological dates suggest a secondary recent rebound centre in the northern part of the basin. Flights of raised beaches, prevalent in the area, are composed of angular limestone fragments and suggest that frost-riving occurs in shallow foreshore environments. The prominent wash line near the marine limit suggests that Foxe Basin had less sea ice cover prior to 6000 years ago but that coastal processes have been similar to present since that time. Key words: Arctic, coasts, archaeology, radiocarbon dating, glacial history, emergence, sea level, geomorphology

Spatial and temporal distribution of Caulobacter spp. in two mesotrophic lakes

The seasonal distribution of Caulobacter spp. has been determined in the water column of two mesotrophic lakes using most probable number (MPN) viable counting techniques from April, 1972 to March, 1973. Concentrations in Lake Washington, a monomictic lake, peaked at 1000–3300 per ml in the epilimnion during the late spring and summer and reached lows in October of less than 2 per ml prior to fall turnover. The reason for the decrease in viable numbers is not known. Caulobacter spp. began to increase gradually in December, during the winter mixing period well before the spring bloom. Concentrations in Hall Lake, a small kettle lake, were somewhat higher than in Lake Washington, ranging from 0.27 per ml in October to over 5000 per ml during May. In contrast to Lake Washington, the highest populations were found in the metalimnion and upper hypolimnion of Hall Lake. Caulobacter spp. were also found in the anaerobic depths of the hypolimnion. However, these did not grow anaerobically, suggesting that they had settled into the hypolimnion and survived in the cold anaerobic zone. The populations of Caulobacter spp. reached maximum numbers at the approximate times and depths at which algal biomass would be expected to be greatest.

Spatial and temporal distribution of Caulobacter spp. in two mesotrophic lakes

The seasonal distribution of Caulobacter spp. has been determined in the water column of two mesotrophic lakes using most probable number (MPN) viable counting techniques from April, 1972 to March, 1973. Concentrations in Lake Washington, a monomictic lake, peaked at 1000–3300 per ml in the epilimnion during the late spring and summer and reached lows in October of less than 2 per ml prior to fall turnover. The reason for the decrease in viable numbers is not known. Caulobacter spp. began to increase gradually in December, during the winter mixing period well before the spring bloom. Concentrations in Hall Lake, a small kettle lake, were somewhat higher than in Lake Washington, ranging from 0.27 per ml in October to over 5000 per ml during May. In contrast to Lake Washington, the highest populations were found in the metalimnion and upper hypolimnion of Hall Lake. Caulobacter spp. were also found in the anaerobic depths of the hypolimnion. However, these did not grow anaerobically, suggesting that they had settled into the hypolimnion and survived in the cold anaerobic zone. The populations of Caulobacter spp. reached maximum numbers at the approximate times and depths at which algal biomass would be expected to be greatest.

Coherent slumping of early postglacial lake sediments at Hall Lake, Ontario, Canada

Cores of organic postglacial sediment from Hall Lake, southern Ontario, Canada, are described. The laminated, calcareous sediments deposited between 9,000 and 8,000 B.P. have coherently slumped into the deep part of the lake, causing overturning and replication of parts of the sequence. This process may be considered as a mechanism for sediment focusing, since it involves reworking of marginal sediments into deeper areas. Unlike previously described mechanisms, it may be a source of error in the interpretation of diagrams of pollen percentages as well as accumulation rates. The slumping has only been recognized through the distortion of the laminae. It might not be possible to recognize slumping in unstratified sequences.

Chrysophycean scales as paleoindicators in the sediments of Hall Lake, Washington, U.S.A.

Twelve species of Mallomonas and ten species of other genera of Mallomonadaceae and Paraphysomonadaceae were found in sediments deposited in Hall Lake from about 1850 to the present. One Mallomonas species (M. portue‐ferreae peterfi & As‐mund) was found that had not previously been reported from North America. The majority of the species have been described as either generally distributed or characteristic of acid or oligotrophic humic waters. M. heterospina Lund and M. multiunca Asmund, which were restricted to sediments deposited during the operation of a sawmill on the lake, have been collected from very eutrophic to dystrophic waters as well. On the whole the species composition indicates a change in the lake from oligotrophic to more eutrophic conditions.

Paleocology of Hall Lake, Washington: A History of Meromixis and Disturbance

Hall Lake, Washington, has been meromictic and holomictic for known periods in the recent past (1950 to 1980). Information on the factors initiating biogenic meromixis in Hall Lake, Washington, was sought using an analysis of the recent sediment in conjunction with known historical events. X-rays of six 50-cm cores showed cryptic laminations that proved to be varves resulting from winter rains, which concentrated silt and clay input in that season. Precise estimation of annual sedimentation rates over the past 350 yr permitted calculations of fluxes of total mineral matter, organic matter, Fe, Ca, Na, K, Pb, Si, Al, Mg, Ti, S, P, chlorophyll degradation products, and cladoceran microfossils. The relative abundance diagrams for pollen and major diatom taxa were also constructed. The sedimentary record left during the known period of meromixis (1950 to 1962) was characterized by mesotrophy, stable mineral flux rates, moderate algal production, stable organic fluxes, and relatively low sedimentation rates, implying insignificant influx of silt-laden waters during winter when meromictic stability is minimal. The absence of sapropel in the sediments during the meromictic era suggests that sapropel is more characteristic of anoxia and adequate Fe and S than of incomplete winter circulation. A change was documented frommore » Daphnia rosea to Daphnia pulex associated with the destruction of meromixis in 1963.Similarly, major changes in the flux of Daphnia rosea and Bosmina longirostris microfossils to the sediments in the lower portion of the core are as yet unexplained. An attempt to study the population dynamics of Daphnia rosea based on size-frequency distributions and using a computer model demonstrated that there is a systematic underrepresentation of the smaller instars preserved in the sediments, making such studies impossible.« less

Fossil diatoms and scales of Chrysophyceae in the recent history of Hall Lake, Washington

SUMMARY. Scales of several members of the Chrysophyceae (family Synuraceae) were examined from a core of the recent sediments of Hall Lake, Washington, in conjunction with a study of fossil diatoms. Both types of microfossils revealed communities changing with the historical development of the lake. Increases in planktonic diatoms and in two species of Mallomonas occurred about the time of European settlement. Several acidophilous species among the Chrysophyta disappeared with the establishment of a sawmill and meromictic conditions in the lake. When extensive road construction around the lake ended the period of meromixis, the ratio of Synuraceae, in general, to diatoms, declined. Besides the change in ratio of Synuraceae to diatoms there was a change in the composition of the community of Synuraceae at that time. Species of Synura that had been rare before became the most abundant, and Mallomonas became relatively rare. Throughout the recent history of the lake the dominant Synuraceae seemed to respond more strongly to disturbance around the lake than the most abundant diatoms; thus, scales of Mallomonas, Synura, and other Synuraceae are valuable microfossils for paleolimnological studies.

Biogenic meromixis and stability in a soft‐water lake1

Hall Lake, Washington, was studied during a period of mcromixis (1950–1953) and during a period of holomixis (1968–1972). Comparisons of thermal cycles, light penetration, chemical distribution, and productivity indicate that the lake had a greater productivity while meromictic, even though the seasonal accumulation of dissolved materials in the deep waters was greater during the holomictic period. Calculations showed that the stability due to chemical stratification was actually greater during the holomictic period, supporting the idea that in biogenic meromictic lakes circulation may be controlled more by thermal phenomena than by chemical stratification. Turbid inflows during winter tended to destroy meromixis, but low transparencies due to algal blooms in summer tended to encourage it and may be the primary way by which biogenic meromictic lakes become permanently stratified.

Treatment of water from different sources for safe drinking of rural poultry and livestock of Bangladesh

The research work was under taken to find out the effect of various treatments on water of different sources with a view to supply safe drinking water for rural poultry and livestock. For that, water of four different sources (lake, river, tap, tube well of BAU campus) were collected during the period from December 2006 to June 2007 and subjected to several treatments with physical (heat) and chemical (Hello tab, bleaching powder, potassium permanganate, alum and acetic acid) means in the Department of Microbiology and Hygiene, Bangladesh Agricultural University, Mymensingh-2202 with a view to get water free from deleterious microorganisms those are easily transmitted through drinking water of the above mentioned sources. Water of all the sources were subjected to microbiological examination before and after treatment. No bacteria was found in the water samples collected from tube well of five places of BAU campus following cultural examination. Gram positive rod shaped bacteria were isolated from the river and tap water of Ishakhan Hall Lake (IHL), Brahmaputra river (BR), Taposhi Rabeya Hall (TRH), Teacher staff quarter (TSQ), Microbiology laboratory (ML) and Bangabandhu Hall (BBH) whereas Gram negative rod shaped bacteria (E. coli) were isolated from the water of IHL, BR and from the tap water of ML and BBH. Gram positive cocci was found only in the tap water of ML. The pre-treatment culture of water samples revealed that the TVC (387 CFU/ml) and TCC (75 CFU/ml) were highest in the water of lake compare to those of other water samples collected from river and taps. As a physical means heat treatment (1000C for 4 to 8 minutes) was highly effective. No single colony was found in all the water samples following treatment with heat. No changes in colour, taste and odour were noticed before and after heat treatment of all the water samples. Among the chemical agents, Hello tab (0.05 g/100 ml) was found to be the most effective to make the water free from all the microbial contamination. The taste, colour and odour of the Hello tab treated water samples were found as normal as safe drinking water. The colour, taste and odour of water treated with bleaching powder, potassium permanganate, alum and acetic acid were also examined and it was found that the colour, taste and odour were not normal after treatment of the water samples. Therefore, it may be concluded that the water treated with Hello tab was found superior compare to the water of other treatments in this study which was found free from microbial contamination and unpleasant taste and order. Key words: Water, microorganisms, chemical agents, heat DOI = 10.3329/bjvm.v6i1.1337 Bangl. J. Vet. Med. (2008). 6 (1): 37-43

Maximum Post-Glacial Marine Submergence in Northern Melville Peninsula

Maps the shore line during the peninsula's maximum submergence, from 1957-1958 field observations north of approx. 68 N. The limit of the post-glacial sea was determined by the highest altitudes at which marine shells and strandlines were found in various localities, and the lowest altitudes of undisturbed ground moraines and perched boulders; locations and altitudes for each of these criteria are mapped and tabulated. The sea rose to an altitude of about 450 ft over most of the region; it covered the low headlands and islands along the west coast (which approximated its present shape), the islands and Proterozoic lowland along the north coast, and the east coast to the steep scarp west of Hall Lake. On the northeast coast, altitudes averaged 100 ft lower than elsewhere, possibly due to the presence of residual ice. The marine limit on the peninsula lower than that (approx. 600 ft.) on Southampton is explained by a lingering ice mass centered over Foxe Basin. The area studied was depressed at least 1,100 ft under this ice mass and should rise another 650 ft.