• Osteological stress markers and habitual behaviors: analyzing the connection at Hierakonpolis, Egypt

      Denton, Nora Lee Cross (2005-05)
      The current project identifies skeletal patterns that indicate habitual behavior using muscle attachment sites, osteoarthritic changes and long-bone robusticity. Using a sample from HK43, a cemetery used by the Naqada II A-C working class (circa 3,800-3,400 B.C.), patterns were determined with respect to sex, and by age group. Those patterns were then compared to hypothesized models of skeletal markers predicted to occur with habitual use of an Egyptian hoe, an ox-drawn ard-style plow, a shaduf (a simple machine used in irrigation), and grinding grain using a saddle quern and grinding stone. The patterns displayed in the sample population correspond to predicted patterns created by habitual activity. Results were determined twice; first by sex, then by age. Females and males were grouped regardless of age, and vice versa. If divided by both, the resulting groups were too small to be compared. Females demonstrated a pattern that was most consistent with grinding grain. Males were determined to have a pattern most consistent with hoeing and using a shaduf The middle adult age group, composed of both males and females, showed a range of skeletal markers that is most consistent with that predicted for plowing. Not all patterns were easily explained, however. The young adult, or 17-24 year old age group displayed a pattern of muscle attachment very similar to the old adult group,>45 years of age. The source of that apparent similarity will have to be addressed by further research at Hierakonpolis, Egypt.
    • Osteology, relationships and paleoecology of a new Arctic hadrosaurid (Dinosauria: ornithopoda) from the Prince Creek formation of Northern Alaska

      Mori, Hirotsugu; Druckeniller, Patrick; Fowell, Sarah; Wooller, Matthew; Hundertmark, Kris (2014-05)
      The Liscomb Bonebed (LBB), found in the early Maastrichtian Prince Creek Formation of northern Alaska, is the single most productive site for the Arctic dinosaurs in either hemisphere. From the LBB, thousands of bones representing at least hundreds of individuals of a saurolophine hadrosaur have been collected, but they have not been previously described and their taxonomic status remains unresolved. In part, this stems from the fact that most material comes from individuals approximately one-half to onefourth of adult size. Another long-standing question concerns whether dinosaurs in the Prince Creek Formation overwintered in the paleo-Arctic or migrated elsewhere (presumably south) to escape prolonged darkness and cold. Here, I attempt to determine the taxonomic status of the LBB hadrosaurs using three semi-independent methods: 1) geometric morphometric analysis; 2) comparative morphological analysis; and 3) cladistic analysis. An important component of this work also includes an ontogenetic study of the growth patterns of the genus Edmontosaurus, to which this material has been previously referred, in order to better understand ontogenetic variation within the Alaskan taxon. My results indicate the Alaskan taxon is a new species of the widespread genus Edmontosaurus. For the first time, the Alaskan taxon is described in detail, making it the best known polar dinosaur to date. My cladistic analysis suggests a possible biogeographic scenario in which the common ancestor of Edmontosaurus and Shantungosaurus originated in eastern Eurasia and then dispersed by the Campanian to North America via a land corridor in the area of present day Alaska. Finally, I used a novel method involving strontium isotope geochemistry to test the migration hypothesis of the new species of Alaskan Edmontosaurus. I measured strontium in tooth enamel of Edmontosaurus and a putative non-migratory species (Troodon) using LA-MC-ICP-MS. My results suggest diagenesis had not significantly altered the signal and that Alaskan Edmontosaurus likely did not migrate during approximately the last four months of life. My results lend further support for the existence of a distinct, early Maastrichtian polar dinosaur fauna known as the Paanaqtat Province.
    • Otters, sea stars, and glacial melt: top-down and bottom-up factors that influence kelp communities

      Traiger, Sarah B.; Konar, Brenda; Hardy, Sarah; Okkonen, Stephen; Edwards, Matthew; Litaker, Wayne (2017-08)
      Kelp beds are important features of the Alaska coastline and provide habitat, protect coastlines, and support commercial and subsistence harvests. Kelp beds are affected by top-down and bottom-up factors, which are changing due to human and climate-related impacts. The influences of these top-down and bottom-up factors on kelp beds are investigated in three chapters. My first chapter investigated the influence of glacial discharge on recruitment and early community development in subtidal kelp communities by monitoring benthic sessile algae and invertebrates on cleared rocks across a glacial gradient along with various physical and biological parameters in the summers of 2013-2014. It has been predicted that Alaska's glaciers will lose 30-60% of their volume by 2100. The melt from glaciers increases sedimentation and lowers salinity, impacting important habitat-providing kelp. I found that sites upstream from glacial discharge had higher kelp recruitment than downstream sites, and that up to 72% of the variation in community development was related to mobile invertebrates and kelp in the surrounding community. Glacially-influenced environmental factors did not explain any variation that was not already explained by biological factors. My second chapter explored whether patterns in the recruitment of the dominant canopy kelp, Nereocystis luetkeana and the subcanopy kelp, Saccharina latissima were a result of dispersal limitation or failure to grow to macroscopic size. My goals were to determine 1) whether glacial melt conditions affect adult fecundity (spore production) of either species, 2) how sedimentation affects early gametophyte growth and survival in each species, and 3) whether competitive interaction between species at the gametophyte stage is altered by sediments. I found that glacial melt conditions did not affect the fecundity of either species, but sedimentation affected survival and competition. Saccharina latissima was the superior competitor under high sediment conditions. Because glacially-influenced coastal areas often have little exposed hard substrate and predation by sea otters and sea stars on clams can provide hard substrate for kelp colonization, my third chapter examined methods for determining predation on clams by these predators without direct observation. I found that foraging pits of sea otters and sea stars could not be distinguished using quantitative measurements. In contrast, shell litter proved useful in quantifying relative foraging rates. Clam consumption by sea otters and sea stars was equal at all but one site. Collectively, my thesis chapters provide information on the effects of glacial discharge on microscopic and early kelp life stages in Alaska which can be incorporated into management practices.
    • Outbreeding depression and inheritance in three generations of geographically distinct southeast Alaska coho salmon (Oncorhynchus kisutch) populations

      Dann, Tyler H. (2009-08)
      I observed no fitness losses among F₂ hybrids of three Southeast Alaska coho salmon (Oncorhynchus kisutch) populations relative to parental controls. Marine survival did not differ among groups in one generation, but was greater for hybrids than controls in another, although the power of these tests was low. Increases in fluctuating asymmetry, which can signal losses in fitness, were not observed. Line cross analyses of length suggested additive and additive plus dominance gene action, and two of three analyses suggested epistasis. In contrast, meristic characters exhibited little variability; and in most cases tests failed to reject a simple additive model. Half- and full-sib analyses provided no evidence of quantitative genetic variation for any trait although the power to detect these effects was low. Comparisons of population divergence measured by quantitative traits (Qst) and molecular markers (Fst) that length is an adaptive trait and that bilateral meristics are highly conserved. Although we did not observe losses in fitness, the power of our tests was low, the among-population differences were unique to our experiment and so results of this study should be interpreted with caution.
    • Outbreeding depression in hybrids between spatially separated pink salmon (Oncorhynchus gorbuscha) populations: marine survival, homing ability, and variability in family size

      Gilk, Sara E. (2003-05)
      Hybridization between distinct populations of salmon can cause fitness loss (outbreeding depression), and may result in reduced survival. The erosion of fitness-related traits such as homing ability and change in family size distribution may underlie reduced survival. Out breeding depression was investigated in two independent experiments that made hybrids between geographically separated and genetically divergent pink salmon populations. Control crosses were made from male and female Auke Creek (Southeast Alaska) pink salmon and hybrid crosses were between Auke Creek females and Pillar Creek (Kodiak Island, about 1000km away) males. Parentage assignment from microsatellite analysis improved estimates of survival and straying, and was used to examine variation in family size. The return rates of even-broodyear F 1 control and hybrid fish were similar, but the odd-broodyear F 1 control returns exceeded hybrid returns. The F 2 control returns exceeded hybrid returns in both the even- and odd broodyears. Hybridization did not impair homing ability; weekly surveys in nearby ( - lkm) Waydelich Creek revealed similar straying rates from Auke Creek by both hybrid and control fish in all years. Family data were available only for even-broodyear returns; hybridization did not increase the index of variability (ratio of variance to mean) in family size in these years. Outbreeding depression in hybrids of geographically separated populations demonstrates the potential for introgression of nonnative fish to erode natural production.
    • Outdoor education and feminism: a review of the outdoor adventures program at the University of Alaska Fairbanks

      Bessent, Danielle; Taylor, Karen M.; May, Amy; Oldmixon, Mark T. (2019-05)
      This report is an organizational review of the Outdoor Adventures (OA) Program at the University of Alaska Fairbanks (UAF). I will be reviewing the communication strategies within the program as well as the risk mitigation and socialization process of the organization. The goal of this document is to provide a theoretical background to justify decision making and communication practices within the organization based on a feminist critical perspective. This document provides recommendations based upon improving communication dynamics that play a role in the gender disparity as well as the processes through which staff of the organization are socialized. This document provides a brief history of the OA program at UAF and a strengths, weaknesses, opportunities, threats (SWOT) analysis to give perspective on the current state of the program. Next this project contains an overview of the gender disparity in the outdoor field, ways in which risk management is viewed and implemented, and the socialization processes of staff members within the program. Methods used to review the organization included document review, direct observation, and autoethnographic practices. The results of this project include documents to aid in socialization and risk management processes and further explores recommendations to mitigate the gender gap, update risk management practices, and train staff.
    • Outpatient care in Fairbanks: supporting people with schizophrenia

      Wiley, Alex; Renes, Susan; Gifford, Valerie; Harrison, Lynn (2015)
      With the current lack of residential treatment facilities, long-term hospitalization, and mental health agencies that can fully support people with schizophrenia in Fairbanks, Alaska, there are many ethical concerns that must be addressed to best support clients with schizophrenia. The ethical considerations present in the success of outpatient care include: a) promoting the welfare of clients, b) utilizing plans that offer reasonable promise of success, c) understanding the limits imposed on the support networks of these clients, and d) the limitations of employment opportunities for these clients in an outpatient setting. Reviewing literature on the experiences of people with schizophrenia revealed three stages of treatment normally experienced: a) acute care, b) transition care, and c) chronic care. Areas most impacted for people with schizophrenia are socialization and work, memory and intelligence, suicide risk and other disorders, and interactions with family, friends and the community. In Fairbanks, Alaska where weather hinders socializing and available services are limited, building many strong support resources is incredibly important to give people with schizophrenia the best chance of recovery and a stable quality of life.
    • Overcoming CubeSat downlink limits with VITAMIN: a new variable coded modulation protocol

      Sielicki, Thomas; Thorsen, Denise; Hamkin, Jon; Hawkins, Joseph; Mayer, Charles (2013-12)
      Many space missions, including low earth orbit CubeSats, communicate in a highly dynamic environment because of variations in geometry, weather, and interference. At the same time, most missions communicate using fixed channel codes, modulations, and symbol rates, resulting in a constant data rate that does not adapt to the dynamic conditions. When conditions are good, the fixed date rate can be far below the theoretical maximum, called the Shannon limit; when conditions are bad, the fixed data rate may not work at all. To move beyond these fixed communications and achieve higher total data volume from emerging high-tech instruments, this thesis investigates the use of error correcting codes and different modulations. Variable coded modulation (VCM) takes advantage of the dynamic link by transmitting more information when the signal-to-noise ratio (SNR) is high. Likewise, VCM can throttle down the information rate when SNR is low without having to stop all communications. VCM outperforms fixed communications which can only operate at a fixed information rate as long as a certain signal threshold is met. This thesis presents a new VCM protocol and tests its performance in both software and hardware simulations. The protocol is geared towards CubeSat downlinks as complexity is focused in the receiver, while the transmission operations are kept simple. This thesis explores bin-packing as a way to optimize the selection of VCM modes based on expected SNR levels over time. Working end-to-end simulations were created using MATLAB and LabVIEW, while the hardware simulations were done with software defined radios. Results show that a CubeSat using VCM communications will deliver twice the data throughput of a fixed communications system.
    • An overview on the author's graduate recital program

      Koukakis, Dimitrios Paganos; Zilberkant, Eduard; Post, William; Celaire, Jaunelle (2016-05)
      The following project paper consists of three chapters, examining the works in my Graduate Recital Program. The first chapter analyzes the form, structure and particular interesting elements that Aram Khachaturian uses in his Sonata for Piano. The second chapter gives a brief historical information of the term Fantasy and examines two examples of the genre, Chopin's Fantasy in F minor op. 49 and Carl Vine's Sonata no. 3 "Fantasia". The third chapter covers some biographical information of Elliott Carter and examines the form and structure of his work for solo piano, 90+.
    • Overwintering Physiology Of Arctic And Subarctic Insects From Interior Alaska

      Sformo, Todd L.; Barnes, Brian; Duman, John; Boyer, Berty; Martinson, Tracey (2009)
      This dissertation focuses on the overwintering of three insects from Interior Alaska: a hemipteran, Elasmostethus interstinctus, and a coleopteran, Cucujus clavipes puniceus, that are freeze avoiding in the strict sense of the phrase, and a dipteran, Exechia nugatoria, that is simultaneously partially freeze avoiding and freeze tolerant. The variability within the freeze avoidance strategy itself is a key theme throughout this dissertation. Two significant contributions to comparative physiology are the confirmation of insect vitrification (glass formation) with its attendant extension of freeze avoidance and survival into a new, extreme low temperature record of -100�C and the simultaneous coupling of freeze avoidance and tolerance within an individual, which may more properly be described as a new overwintering strategy. Vitrification is the process by which ice crystallization is circumvented, resulting in a supercooled amorphous solid. Through a combination of antifreeze proteins that inhibit ice nucleation, dehydration tolerance, presence of high glycerol concentration, and low temperatures, the mobility of the remaining liquid water molecules is reduced, effectively by-passing the crystalline state. The second contribution is the discovery of a new overwintering strategy that combines freeze avoidance and freeze tolerance within an individual. In this case, the abdomen freezes (and the insect survives), while the contiguous head/thorax remains supercooled. These findings lead to the following evolutionary and trans-disciplinary questions. Is vitrification an adaptation? What is the selective advantage of compartmentalizing ice between body sections of an individual insect? Is this new overwintering strategy an example of a species transitioning between either becoming exclusively freeze avoiding or free tolerant? Applying new understanding of mechanisms of insect vitrification and avoidance of devitrification to cryomedicine may extend preservation of human tissues and organs. Similarly, for physical and material scientists, by understanding the patterns of ice formation within insects that tolerate, inhibit, and/or impede ice formation below the homogeneous ice nucleation temperature of water (-40�C), new biomimetic possibilities can be envisioned.
    • Oxidative stress is transient and tissue-specific during cold acclimation of threespine sticklebacks

      Kammer, Aaron R. (2010-08)
      We sought to determine if oxidative stress occurs in liver, oxidative muscle or glycolytic muscle of threespine sticklebacks during cold acclimation. Fishes were held at 20°C for 12 wks and then acclimated to 8°C for 9 wks or held at 20°C for an additional 9 wks. Animals were harvested during the first four days of cold acclimation, and at wk 1, 4 and 9. Protein carbonyls were quantified as an indirect measure of the production of reactive oxygen species (ROS). The activity of superoxide dismutase (SOD), levels of SOD mRNA, and glutathione levels were quantified as indices of protection against ROS. All measurements were made in liver, glycolytic muscle and oxidative muscle. Protein carbonyl levels increased in livers of fishes after 1 wk at 8°C and decreased after wk 4. Total glutathione levels increased in livers on day 3 of cold acclimation and then decreased by wk 4. Measured at a common temperature, SOD activity increased early in all tissues and remained elevated throughout cold acclimation. Measured at the acclimation temperature, SOD activity increased only in oxidative muscle after 9 wks of cold acclimation. Together, these results indicate that oxidative stress is transient and tissue-specific during cold acclimation of fishes.
    • Oxytetracycline tags in pink salmon fry applied by immersion and detected by fluorescence spectrometry

      Page, Timothy Kent (1989-05)
      I investigated the feasibility of using spectrophotofluorescence as a quantitative method of analyzing pink salmon fry otoliths for the presence of oxytetracycline (antibiotic). I exposed twenty-four groups of pink salmon fry (approximately 250 individuals each) to solutions of oxytetracycline ranging in concentration from unexposed to 2000 ppm, and in duration of exposure from one to twelve hours. Otoliths from unexposed fry had the lowest mean fluorescence (log e [mean flu. units] = -1.77). Otoliths from fry exposed to 500 ppm for twelve hours had the highest fluorescence (log e [mean flu. units] = 0.899). Fluorescence increased nonlinearly with duration of exposure. There is a linear increase of fluorescence with exposure up to 500 ppm; above which fluorescence decreases. Pink salmon fry exposed to OTC in solution absorb detectable amounts of OTC in their otoliths. These amounts of OTC can be quantitatively measured by spectrofluorometry.
    • Ozone depletion and biologically relevant ultraviolet radiation

      Zeng, Jun; Stamnes, Knut; Benner, Richard; Bowling, Sue Ann; Eslinger, David; Kawasaki, Koji; Watkins, Brenton (1995)
      An atmospheric radiative transfer model is used to calculate surface spectral ultraviolet irradiance under cloud-free conditions, and compared with measurements made at Lauder, New Zealand (45$\sp\circ{S}$, 170$\sp\circ{E})$ before and after the eruption of Mt. Pinatubo, and including a snow-covered surface. The ratios of diffuse to direct irradiance depend critically on solar elevation, surface albedo, and aerosol extinction. Ozone changes have pronounced effects on the global UVB irradiance, but have only a minor effect on these ratios. The comparison suggests that the ultraviolet radiation exposure can be computed with confidence for clear sky conditions, if the appropriate atmospheric pressure and temperature profiles, ozonesonde data, surface albedo, and aerosol optical properties are available. The total ozone abundances are derived by using ground-based UV irradiance measurements and compared with TOMS in Antarctica and the Arctic from 1990 to 1994. The comparisons show that they are generally in good agreement. Possible reasons for the discrepancies between the two methods are discussed. The equivalent cloud optical depths are also inferred from these data. Ozone depletion can also increase the penetration of ultraviolet radiation into the aquatic system. A coupled atmosphere-ocean radiative transfer model is used to investigate the effect of ozone depletion on UV penetration through the atmosphere and into the underlying water column. Comparisons between model computations and in situ measurements of irradiances made in Antarctic water show good agreement in the UV spectral range between 300 and 350 nm. The ratio of UVB (280-320 nm) to total (280-700 nm) irradiance also compared well. For a given ozone reduction the largest relative increase of UVB radiation arriving at the surface and penetrating to various depths in the ocean occurs at large solar zenith angles. At high latitudes the most pronounced increase in UVB exposure due to an ozone depletion occurs in the early spring, when ozone depletion is expected to be the most severe. The sensitivities of irradiance reflectance and diffuse attenuation coefficients to solar zenith angle, sky conditions, and chlorophyll concentration are discussed by using a coupled atmosphere-ocean radiative transfer model. The irradiance reflectance is sensitive to solar zenith angle, cloud cover, and chlorophyll concentration; the diffuse attenuation coefficient is sensitive to solar zenith angle and chlorophyll concentration, but less sensitive to sky conditions.
    • Pacific sleeper sharks in the Northeast Pacific Ocean: relative abundance, plausible incidental exploitation rates, trophic ecology, and habitat use

      Courtney, Dean Louis; Adkison, Milo D.; Foy, Robert; Sigler, Mike; Criddle, Keith R.; DiNardo, Gerard (2017-12)
      Pacific sleeper shark relative abundance indices in the eastern Bering Sea and Gulf of Alaska were developed from sablefish longline surveys and the sustainability of a plausible range in Pacific sleeper shark incidental exploitation rates in the Gulf of Alaska was evaluated with a risk analysis using Monte Carlo simulation for use in fisheries management. A significant increase in Pacific sleeper shark relative abundance was identified in the Gulf of Alaska during the years 1989-2003. The aggregate risk of ending in an overfished condition in the Gulf of Alaska increased from 0% under a low exploitation rate scenario to 59% under a high exploitation rate scenario. Baseline information about Pacific sleeper shark trophic ecology and habitat utilization in the eastern Bering Sea and Gulf of Alaska was developed for use in ecosystem-based fishery management. Analysis of stable isotope ratios of nitrogen (δ¹⁵N) and lipid normalized carbon (δ¹³C′) identified significant geographic and ontogenetic variability in the trophic ecology of Pacific sleeper sharks in the eastern Bering Sea and Gulf of Alaska and revealed wider variability in the feeding ecology of Pacific sleeper sharks than previously obtained from diet data based on stomach contents alone. Time series analysis of Pacific sleeper shark electronic tag data from the Gulf of Alaska identified a simple autoregressive relationship governing short-term movements (hours) throughout the time series which included substantial variation in longer time period movement patterns (months) and demonstrated that statistical inference about habitat utilization could be drawn from simultaneous analysis of an entire time series depth profile (six months of data) stored on an electronic archival tag.
    • Pacific walrus use of higher trophic level prey and the relation to sea ice extent, body condition, and trichinellosis

      Seymour, Jill-Marie; Horstmann-Dehn, Lara; Atkinson, Shannon; Barboza, Perry; Rosa, Cheryl; Sheffield, Gay; Wooller, Matthew (2014-05)
      The changing Arctic ecosystem may prompt Pacific walruses (Odobenus rosmarus divergens) to change their usual diet of lower trophic level prey (e.g., benthic invertebrates) by increasing the consumption of higher trophic level prey (HTLP). Prey-switching may have consequences to walrus populations through increased energetic costs, increased stress response, declines in body condition, and exposure to diseases, including the zoonotic parasite Trichinella spp. Trichinella is possibly transmitted to walruses via predation or scavenging on seals. The goal of this study was to quantify reliance on HTLP using stable carbon and nitrogen isotope ratios, and assess potential correlations among consumption of HTLP and sea ice extent, sex, Trichinella infection, body lipid stores, and cortisol concentrations used as an index of the stress response. Walrus diet is comprised of ~1-22% HTLP and reliance on HTLP may be correlated with sea ice extent in a complex way. Trichinella was present in ringed seal (Pusa hispida, 1/57), Arctic fox (Vulpes lagopus, 3-7/32), and polar bear (Ursus maritimus, 1/1), but was not detected in walruses (0/137) regardless of %HTLP in the diet. Walrus blubber and attached skin contained 44.6 ±12.4% lipid wet weight, which was lower than that found for other Arctic marine mammals; however, the inclusion of skin likely decreased our %lipid values. While the absolute value of %lipid from blubber and attached skin was not a suitable substitute for %lipid from blubber only, we were still able to detect the influence of biological factors, with sex-linked variability in walrus lipid stores observed. Cortisol analysis from full-thickness blubber resulted in a wide range of concentrations (2.77 to 34.04 ng/g), but showed that this stress hormone can be extracted from blubber. While neither %lipid nor blubber cortisol was correlated with the proportion of HTLP in walrus diet, they may serve as minimally-invasive methods for health monitoring of walruses. Overall, dietary plasticity of walruses is robust and switching to HTLP is not likely to have immediate adverse effects on the Pacific walrus population.
    • Pairwise comparisons of shrub change across alpine climates show heterogeneous response to temperature in Dall's Sheep range

      Melham, Mark; Valentine, Dave; Panda, Santosh; Brinkman, Todd (2019-12)
      Encroachment of woody vegetation into alpine and high latitude systems complicates resource use for specialist wildlife species. We converted Landsat imagery to maps of percent shrub cover in alpine areas of Dall's sheep (Ovis dalli dalli) range. We then compared percent cover to interpolated climate data to infer drivers of shrub change between the 1980s and 2010s and determine if that change is occurring at different rates in climatically distinct alpine areas. We identified areas spatially interconnected by their mean July temperature intervals and compared their rates of shrub change, finding net rates of shrub growth were higher at temperatures notably above shrub growing season minimums. Along a climatic gradient, high precipitation areas had highest net shrub change, Arctic areas followed, while alpine areas of interior Alaska and the cold Arctic showed the least amount of net shrub change at these higher temperatures. Despite the requirement of higher temperatures for shrub growth, temperature and net shrub change displayed different relationships across the range wide climatic gradient. In areas of rapid climate warming, such as the Arctic and cold Arctic, the linear correlation between shrub change and temperature was highest. In the high precipitation areas where temperatures have been largely above growing season minimums during the study period, precipitation had the strongest linear correlation with shrub change. High latitude studies on shrub change focus primarily on expansion in the Arctic, where increased greening trends are linked to higher rates of warming. We provide the broadest climatic examination of shrub change and its drivers in Alaska and suggest shrub expansion 1) occurs more broadly than just in areas of notable climate warming and 2) is dependent on different environmental factors based on regional climate. The implications for Dall's sheep are complicated and further research is necessary to understand their adaptive capacity in response to this widespread vegetative shift.
    • Paleobiology of ichthyosaurs: using osteohistology to test hypotheses of growth rates and metabolism in a clade of secondarily aquatic marine tetrapods

      Anderson, Katherine L.; Druckenmiller, Patrick; Erickson, Gregory; Horstmann, Lara; Fowell, Sarah (2019-08)
      Ichthyosaurians (Ichthyosauria) are one of the most prominent groups of secondarily aquatic Mesozoic marine reptiles. Over their 160 million years of evolution, the clade evolved a streamlined body plan with paddle-like limbs, convergent with modern cetaceans. Despite the fact that ichthyosaurians have been studied by paleontologists for over a century, very little is known about aspects of their biology, including quantification of their age structure and growth rates. Multiple lines of evidence, including oxygen isotope, swimming modality, and body shape analyses suggest that ichthyosaurians experienced elevated growth rates and likely maintained an elevated body temperature relative to ambient sea water. In this dissertation, I test these hypotheses using osteohistological methods. In the first manuscript, we describe new material of the small-bodied Upper Triassic ichthyosaurian Toretocnemus from the Nehenta Formation and the Hound Island Volcanics (both Norian, Upper Triassic) of Southeast Alaska. During the Upper Triassic, ichthyosaurians experienced their greatest size disparity, with large-bodied species rivaling the size of modern blue whales (Balaenoptera musculus; 20+ m body length) living alongside small-bodied species (1 m body length) like Toretocnemus. Prior to this study, Toretocnemus was known from Carnian deposits of California and possibly Sonora, Mexico. The referred material described here expands its geographic and temporal range. There are very few known ichthyosaurians from the Norian; thus, this material sheds light on the clade's diversity before the end Triassic extinction event. In the second and third manuscripts, we use osteohistological methods to describe the microstructure of various skeletal elements of two species of Stenopterygius from the Posidonia Shale (Lower Jurassic) of Germany. The Posidonia Shale is a Konservat-Lagerstätten that preserves over 3000 ichthyosaurian specimens, approximately 80 percent of which are referable to Stenopterygius. First, we sampled over 40 skeletal elements from one individual specimen referred to Stenopterygius quadriscissus to 1) describe the mineralized tissues across the skeleton, 2) infer relative growth rate, and 3) identify elements with growth marks. Almost all elements described demonstrate fibrolamellar primary bone, indicative of a rapid growth rate. We also identify growth marks in several elements, including the dentary and premaxilla, that will be used in future growth studies. In the third manuscript, we sample a scleral ossicle from Stenopterygius triscissus to describe its microstructure and investigate the use of ossicles for skeletochronology. The use of scleral ossicles for determining age structure has been documented in extant sea turtles as well as dinosaurs. We sectioned one ossicle in three planes and document conspicuous growth banding in the short axis section. Although this method requires further testing, we tentatively determine a minimum age of 7 years at the time of death for this individual. This dissertation lays critical groundwork for future studies of the paleobiology of ichthyosaurians. We are already in the preliminary stages of using these results to 1) quantify age structure and growth rates of an ichthyosaurian (Stenopterygius quadriscissus) for the first time, and 2) test the use of scleral ossicles for skeletochronology of ichthyosaurians. Through addressing these basic aspects of ichthyosaurian biology, we can begin to investigate how ichthyosaurian development and physiology changed over time and space and develop a greater understanding of this clade's 160 million years of evolution.
    • Paleoceanographic shifts in the Gulf of Alaska over the past 2000 years: A Multi-proxy perspective

      Boughan, Molly McCall; Finney, Bruce; Naidu, Sathy; Whitledge, Terry E. (2008-12)
      The Gulf of Alaska (GOA) is a dynamic region influenced by climate variability on time scales ranging from days to millennia. Recent regime shifts suggest interdecadal GOA primary productivity patterns, yet it is unclear whether such fluctuations extend beyond the instrumental record. This thesis examined the nature of prevalent climatic and oceanographic patterns before the twentieth century using several marine sediment core proxies for paleoproductivity and paleoceanography. Sediment cores were from two locations: Bay of Pillars, Kuiu Island, in southeast Alaska (56.63 ̊N, 134.35 ̊W), and a central midshelf location (GAK4) along the Global Ecosystem Dynamics (GLOBEC) Seward Line (59.25 ̊N, 148.82 ̊ W). Proxy data from these cores include: percentages of organic carbon, nitrogen and biogenic opal; organic carbon-to-nitrogen ratios; stable isotope ratios from sediment organic matter (δ13C and δ15N) and foraminifera tests (δ13C and δ18O); and foraminifera faunal analysis. Bay of Pillars proxy data suggest that the onset of the Little Ice Age (LIA) ca. 1200 AD coincides with pulses of decreased salinity and increased productivity. GAK4 proxy data indicate increased productivity and decreased terrestrial input over the past century; as well as fresher surface water was during the latter portion of the LIA (1716 – 1894) and positive Pacific Decadal Oscillation phases.
    • Paleoclimate and paleoenvironment of the Prince Creek and Cantwell formations, Alaska: terrestrial evidence of middle Maastrichtian greenhouse event

      Salazar Jaramillo, Susana; Fowell, Sarah; McCarthy, Paul; Trainor, Tom; Druckenmiller, Patrick (2014-05)
      I studied the paleoclimate and paleoenvironmental conditions of the Prince Creek Formation, North Slope Alaska, and the lower Cantwell Formation in Denali National Park, Alaska. I used data from pollen analysis, clay mineral analysis and stable isotope analysis of clay minerals and organic matter applied to paleosols of the Prince Creek Formation. In the lower Cantwell Formation, I reconstructed the sedimentary environment, produced a terrestrial carbon stable isotope record and obtained a ~ 69.5 Ma radiometric age for the lower Cantwell Formation. Clay analysis in the Prince Creek Formation indicates that the genesis of the paleosols was strongly influenced by the properties of the parent material and that an epiclastic bentonitic source contributed to the development of non-allophanic properties which suggests the presence of Andept-like paleosols. Paleosols formed on the floodplains of the Prince Creek Formation reveal features attributed to wet-dry cycles as a result of seasonal flooding, perhaps due to snow melt in the ancestral Brooks Range. Carbon and oxygen isotope analyses, and the geochemistry of paleosol Bw/Bt horizons indicate mean annual precipitation values between 745.56 and 1426.88 ±221.38 mm/yr and mean annual temperatures of 12 ±4.4 °C. The meteoric water δ¹⁸O value calculated from smectite at a 6.3 °C mean annual temperature is ~-24 ⁰/₀₀. The calculated value is δ¹⁸O-depleted as is expected for high latitudes during the Late Cretaceous. Sedimentary facies analysis suggests that The East Fork measured section of the lower Cantwell Formation was likely deposited in the distal part of an alluvial fan. A new U-Pb age of 69.5 ±0.7 Ma from bentonites and carbon isotope values of bulk sedimentary organic matter and wood fragments indicates that a greenhouse event, known as the mid-Maastrichtian Event (MME), is recorded at the East Fork of the Toklat River Section. A mean annual precipitation value of ~ 517.92 ±134.44 mm/yr was obtained from δ¹⁸O terrestrial organic matter. The coeval nature of the lower Cantwell Formation (~69.5 Ma) and the Prince Creek Formation (~69.2 Ma) suggests that the MME likely affected the Prince Creek Formation as well. In the Prince Creek Formation, the age, precipitation, temperature and meteoric water composition from bentonite smectites are consistent with increased precipitation due to an intensified paleo-arctic hydrological cycle, which may have been the result of increased latent heat transport during the mid-Maastrichtian greenhouse episode.