Gsa 125Th Anniversary - 2013 Trilobite Abstracts

[piranha]

The GSA annual meeting and symposium October 27-30 in Denver celebrates the GSA 125th Anniversary. The list of attendees for this big event is an incredible honor roll of paleontologists. Follow the <LINK> to the GSA website for the complete list of scheduled posters. The following abstracts represent all of the trilobite related presentations and current studies in progress. Some of these will eventually get published so always interesting to follow.

The next best thing to being there.... Enjoy!

Paper No. 29-2 - CLADAL TURNOVER: THE END-ORODVICIAN MASS EXTINCTION EVENT AS A LARGE SCALE ANALOG OF VRBA'S RELAY MODEL.

CONGREVE, Curtis R., Geology, University of Kansas, Lawrence, KS 66045

The end-Ordovician mass extinction occurred in two distinct pulses, the first pulse associated with the initial onset of severe glaciation in the beginning of the Hirnantian period and the second pulse associated with the receding of the glaciers near the end of the Hirnantian. In between these two pulses there was a brief period of recovery, in which putatively cold-water taxa referred to as the Hirnantia fauna diversified and spread equatorially. These Hirnantia taxa then preferentially went extinct at the second pulse of extinction. This pattern of pulsed speciation and extinction is analogous to the patterns predicted in Vrba’s Relay Model, in which a sudden environmental shift towards cold temperatures could cause habitat fractionation and extinction in warm-water taxa as well as range expansion and speciation in cold-water taxa. Therefore, a model is proposed for the extinction/speciation patterns of the end-Ordovician which is a large scale analog of Vrba’s Relay Model, named the Cladal Turnover Model. A test is outlined which can be used to determine if the Cladal Turnover is occurring in the end-Ordovician. A case study is then performed on specific Hirnantia taxa, the trilobite genus ‘Brongniartella’. The results of this test suggest that, while the taxon ‘Brongniartella’ is derived from putatively cold-water high latitude stock (consistent with the classical definition of the Hirnantia taxa), the group does not go extinct at the end-Ordovician event and instead gives rise to warm-water low latitude descendants. This result is consistent with the Cladal Turnover Model. The extinction patterns of non-Hirnantia trilobite taxa (specifically the Deiphoninae, Sphaerexochinae, and Ceraurids) are also compared to the Cladal Turnover Model to determine if the patterns of speciation and extinction and consistent with the model.

Paper No. 29-3 - ADAPTIVE RADIATIONS IN THE CONTEXT OF MACROEVOLUTIONARY THEORY.

LIEBERMAN, Bruce S., Ecology & Evolutionary Biology, University of Kansas, 1345 Jayhawk Blvd, Dyche Hall, Lawrence, KS 66045

Adaptive radiations are often invoked anytime clades show significant bursts of diversification, but it is important to not simply assume that any radiating clade constitutes an adaptive radiation. Here a macroevolutionary theoretic framework is developed, using specific examples from the fossil record, especially those involving trilobites, for identifying and defining various types of evolutionary radiations, including adaptive radiations. This framework builds on the fact that several highly relevant macroevolutionary concepts including the Turnover Pulse Hypothesis, the Effect Hypothesis, and species selection, have not previously been considered in the adaptive radiations literature; here these are more fully integrated into the theory of adaptive radiations. In addition, the relevance of whether radiations might have been driven by exaptations instead of adaptations is emphasized. Another important issue considered is the centrality of monophyly to the identification of an evolutionary radiation. For example, phenomena informally treated as evolutionary radiations, such as the Cambrian radiation, should in actuality be considered not as one but several separate evolutionary radiations: radiations where adaptation likely played little if any role in spurring diversification. Ironically the fossil record, the source of the initial hallmark examples of adaptive radiation, now appears to show little concrete support for this phenomenon. Other types of evolutionary radiations are identified, including geographic radiations, which are driven by opportunities for allopatric speciation created by geologic or climatic change, or a taxon’s presence in a geographically complex region. Potential examples of adaptive radiation are here consigned to only a single quadrant of the various types of evolutionary radiation. Even within that quadrant there can be either exaptive or adaptive radiations. Special emphasis is also placed on considering the role that abiotic as opposed to biotic factors may play in motivating diversification during evolutionary radiations in general, and adaptive and exaptive radiations in particular.

Paper No. 36-1 - GEOMETRIC MORPHOMETRIC ONTOGENY OF THE TRILOBITE CALYPTAULAX: SHAPE CHANGE DURING THE MERASPID-HOLASPID TRANSITION.

MCDANIEL, Jennifer, Geosciences, Midwestern State University, 3410 Taft Blvd, Wichita Falls, TX 76308, and CARLUCCI, Jesse R., Department of Geosciences, Midwestern State University, Wichita Falls, TX 76308

A combined landmark and semi-landmark based study of the ontogeny of the trilobite Calyptaulax demonstrates the extent to which shape is dependent on size as meraspids develop into holaspids. Silicified individuals from the Edinburg Formation of Virginia form the raw material for the dataset, and vary in cranidial length from approximately 1 mm to 1 cm. Landmarks are primarily intersections and end points of cranidial furrows, and a semi-landmark curve summarizes cranidial shape along the facial suture. A bivariate plot of procrustes distance and log centroid size demonstrates the linear aspects of the ontogenetic trajectory across the meraspid-holapsid boundary. To test if growth is allometric in Calyptaulax, we conducted a multivariate regression of partial warp scores from a mean reference form against log centroid size. Results of the regression indicate statistically significant allometric growth across the meraspid-holaspid transition in Calyptaulax. Thin plate spline deformation grids based on the regression analysis summarize a series of morphological changes during ontogeny, most notably the lateral deflection of furrows S1, S2, S3, and axial furrow. In addition, the anterior portion of the glabella becomes more angular during ontogeny and the meraspids lose a prominent occipital tubercle.

Paper No. 36-16 - PHYLOGENETIC ANALYSIS OF LATE ORDOVICIAN NORTH AMERICAN BATHYURID TRILOBITE GENERA RAYMONDITES AND BATHYURUS.

SWISHER, Robert E., Geological Sciences, University of Oklahoma, Oklahoma Museum of Natural History and School of Geology & Geophysics, Norman, OK 73072, and WESTROP, Stephen R., Oklahoma Museum of Natural History and School of Geology & Geophysics, Univ of Oklahoma, Norman, OK 73072

The youngest genera of Late Ordovician bathyurid trilobites, Raymondites and Bathyurus have a rich history of study, but suffer from a lack of recent systematic or phylogenetic analysis, especially for Raymondites. These taxa occur in Late Ordovician, Mohawkian (Sandbian-Kaitian) strata of North America (Laurentia) during a period of significant paleoenvironmental shifts, due to the onset of the Taconic orogeny and global climate cooling (GICE excursion). Systematic and phylogenetic studies of these genera and others from this time provides a framework for better understanding evolutionary trends during times of dramatic environmental shifts.
While a number of species are currently known for Raymondites systematic work has been complicated by the relative rareness of material. R. bandifer is only known from its holotype, while other members are often represented by material in poor condition, with limited quantities available. The goal of this study is to revise Raymondites to broaden the understanding of family Bathyuridae by placing the genus into a phylogenetic context with Bathyurus and provide a better understanding of their evolutionary history. This revision re-examines the current Raymondites material and includes previously undescribed material from the Royal Ontario Museum, Toronto, Ontario, Canada (ROM) and a new Raymondites species from the Kimmswick Limestone, Mo. For this study a phylogenetic analysis was conducted using parsimony analysis from a character state matrix compiled from data on cranidium, librigena, and pygidium character states. Results from the analysis support a monophyletic Raymondites clade while Bathyurus is interpreted to form a paraphyletic clade. Raymondites is distinguished by: 1) a reduced palpebral length vs. glabella length ratio, 2) elongate genal spines, 3) expanded lateral and anterior margins, 4) occipital and axial pygidial spines in the majority of members.

Paper No. 36-26 - GEOGRAPHIC VARIATION AND GROWTH OF THE MIDDLE DEVONIAN TRILOBITE ELDREDGEOPS RANA AS A MEANS OF TESTING THE GEOGRAPHIC ISOLATION OF THE MICHIGAN AND APPALACHIAN BASINS.

WITTE, Matthew and YACOBUCCI, Margaret M., Department of Geology, Bowling Green State University, 190 Overman Hall, Bowling Green, OH 43403

The extent of mixing of marine faunas of the Michigan and Appalachian Basins during the Middle Devonian period is unclear. Using growth trajectories and morphological variation of the trilobite Eldredgeops rana, we attempt to discover the degree of divergence between populations in these basins. Morphological divergence may be used as a proxy for genetic and geographic isolation; a lack of divergence implies the two ocean basins were not fully separated during the Middle Devonian. Nearly 300 specimens of E. rana were examined from university and museum collections; they represent a large geographic range encompassing both the Michigan and Appalachian Basins. Included localities are: the Silica Shale near Sylvania, Ohio, and Milan, Michigan; the Plum Brook Shale in Erie County, Ohio; the Moscow Shale in western New York; and the Traverse Group of Alpena County, Michigan. Measurements of the glabella length and width were taken and plotted against each other to create growth trajectories of each geographic population. Trajectories were fitted to a power function. Specimens with adequate preservation were then photographed and subjected to morphometric analysis, using 26 landmarks across the trilobite cephalon. Morphological variation within and between populations was analyzed to infer the degree of genetic variation and geographic divergence. Growth trajectories for each basin were nearly identical across the sampled size range. Morphometric data suggest a lack of divergence, indicating that populations of E. rana were likely mixing across different geographic areas, leading to genetic stasis. The Michigan Basin and Appalachian Basins therefore likely maintained a connection throughout the Middle Devonian period.

Paper No. 36-29 - SURVIVING THE CAMBRIAN EXPLOSION: QINELLA FROM DEATH VALLEY, CALIFORNIA.

MCMENAMIN, Mark A.S.1, HUGHES, Whitney A.1, and MCMENAMIN, Jessica M.2, (1) Geology and Geography, Mount Holyoke College, South Hadley, MA 01075, (2) The Orchard School, 63 Silver Street, South Hadley, MA 01075

The small shelly fossil Qinella occurs in an oolite sample from the Lower Cambrian Wood Canyon Formation, Echo Canyon, Death Valley, California. Until now, Qinella has been reported exclusively from upper Proterozoic strata. The Death Valley specimens reach 3.5 mm diameter, and are preserved in limestone matrix that hosts ooids, trilobites, and archaeocyaths with lumpy, cerebroid coatings. Although reworked, the Qinella specimens are not derived from Proterozoic deposits, as one specimen has a trilobite fragment lodged deeply in its interior. The fossils were collected under permit from an elevated desert pavement surface during a Mount Holyoke College expedition to Death Valley. The oolite sample suite was initially thought to belong to the Proterozoic Johnnie Formation. Thin sections, however, revealed the presence of juvenile ethmophylloid archaeocyaths occurring as coated grain nuclei alongside the Qinella. Cerebroid ooids characterize the lower oolite of the upper Wood Canyon Formation. Under cathodoluminescence, the small shelly fossils reveal characteristic Qinella wall structure, manifest as nested, loosely‑spaced cylindrical walls of variable thickness. Walls may thin and pinch out against adjacent walls, as seen in both transverse and longitudinal section. Qinella, also known from the Proterozoic La Ciénega Formation of Sonora, México, is one of very few genera known to survive the Cambrian explosion. Qinella's wall structure evidently provided a formidable defense against boring micropredators. The enhanced protection afforded by its multilamellate shell allowed Qinella to survive well into the Cambrian.

Paper No. 66-8 - CAMBRIAN TRANSGRESSION AND 'EXPLOSION' OF METAZOAN LIFE LINKED TO OPENING OF IAPETUS-PACIFIC OCEANIC CONNECTION.

DALZIEL, Ian W.D., Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, 10100 Burnet Road (R2200), Austin, TX 78758-4445

The abrupt appearance of almost all animal phyla in the fossil record is often colloquially referred to as the Cambrian ‘explosion’ of life on Earth. It is also named ‘Darwin’s dilemma,’ as he appreciated that this seemingly mysterious event posed a major problem for his theory of evolution by natural selection. It coincided with a time of major marine transgression over all the continents. Although the metazoan ‘explosion’ is now seen as more protracted than formerly recognized, it is still regarded one of the most critical events in the history of the biosphere. One of the most striking aspects of the earliest Cambrian fossils is geographic differentiation. In particular, the first benthic trilobite faunas on Laurentia, ancestral North America, and the newly amalgamated southern supercontinent of Gondwana are distinctly different. This has led to the suggestion of an unknown vicariant event intervening between an ancestral trilobite clade and higher members that are represented in the fossil record, possibly one related to the breakup of a supercontinent. Laurentia is bordered by latest Precambrian-Cambrian rifted margins and must therefore have been located within a Precambrian supercontinent. Geochronologic and geochemical evidence indicates that it was attached to part of the East Antarctic craton in the late Mesoproterozoic. Igneous rocks on both continents indicate that rifting to sever that link occurred just prior to the first appearance of trilobites in the fossil record. This event would have separated the Olenellid trilobite fauna of Laurentia from the Redlichiid fauna of Gondwana by opening a major oceanic connection between the developing Iapetus and pre-existing Pacific ocean basins with profound global environmental effects at the time of the Cambrian ‘explosion,’ including expansion of continental shelves. The paleogeographic settings of the two great transgressions of the Phanerozoic, the Cambrian and Cretaceous, are remarkably similar. Both seem to have involved comparatively rapid increase in ridge crest length within the ocean basins of the time.

Paper No. 89-10 - ALASKAN TRILOBITES REVISITED: NEW INSIGHTS TO CAMBRIAN-ORDOVICIAN PALEOGEOGRAPHY FROM FAUNAS OF THE NANOOK LIMESTONE.

TAYLOR, John F., Geoscience Dept, Indiana University of Pennsylvania, Indiana, PA 15705, and STRAUSS, Justin V., Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138

Uniquely Laurentian trilobites recently identified from the Nanook Limestone in the Shublik Mountains of northern Alaska refute earlier claims of a non-Laurentian (likely Siberian) origin for the North Slope Subterrane (NSS) of the Arctic Alaska Terrane. The presence of the upper Cambrian species Plethopeltis armatus (Billings) confirms that the Nanook formed as part of the Laurentian carbonate platform, most likely in proximity to the parts of that platform that are now located in the northern Atlantic region, such as Greenland and Svalbard. Lower Ordovician faunas from the Nanook provide additional support for such an origin. A moderately diverse, hystricurid-dominated fauna includes taxa strongly resembling those recently described from uppermost Skullrockian and basal Stairsian strata in Svalbard. Among these is a hystricurid previously misidentified as “Hystricurus" sainsburyi Ross, which is a species that was described from a fauna of distinctly Siberian aspect in western Alaska. The Nanook fauna also includes two species of Paraplethopeltis, the genus that dominates basal Stairsian faunas in many areas of North America, including Greenland. Although the fauna containing Paraplethopeltis lacks the other genera that typically occur with it in southern Canada and the USA, specifically Kainella and Leiostegium, positive carbon isotopic values obtained from these rocks confirm that they are basal Stairsian strata. A slightly younger fauna from the Nanook includes the first bathyurid trilobite reported from the NSS. This bathyurid species is certainly congeneric, and perhaps conspecific, with a species used to define the basal zone of the Tulean Stage in Svalbard.

Paper No. 123-1 - EXCEPTIONAL PRESERVATION IN THE ORDOVICIAN – CONTRASTING SETTINGS REVIEWED.

BRIGGS, Derek E.G., Geology and Geophysics, Yale University, New Haven, CT 06520

Environmental conditions during the Cambrian favored the fossilization of soft-bodied organisms, particularly in Burgess Shale-type preservations. Soft-bodied organisms are less well represented during the ~42 million years of the Ordovician but this situation is being remedied by new discoveries. Exceptional preservation occurs where suitable facies and conditions are present. The early Ordovician Fezouata formations of Morocco yield a diverse Burgess Shale-type fauna representing a normal marine setting which casts important light on the early stages of the Great Ordovician Biodiversification Event. Other exceptionally preserved Ordovician faunas are much less diverse and represent more unusual environments. The middle Ordovician Winnishiek Lagerstätte of Iowa is preserved in an impact crater, and the late Ordovician Beecher's Trilobite Bed near Rome, New York, represents an iron-dominated low oxygen deeper water setting. (Other important late Ordovician examples include the cold water Soom Shale in South Africa and faunas from Manitoba in Canada.) Silurian exceptional preservations are no more abundant, but the fully marine Herefordshire biota in the Wenlock of England, preserved in concretions in volcanic ash, is remarkable. Such Konservat-Lagerstätten continue to yield new discoveries that underpin our understanding of the phylogeny and Paleozoic history of marine animals.

Paper No. 126-30 - INTEGRATION OF SEQUENCE STRATIGRAPHY AND TRILOBITE PALEOECOLOGICAL PATTERNS: AN EXAMPLE FROM THE UPPER ORDOVICIAN OF OKLAHOMA.

CARLUCCI, Jesse R., Department of Geosciences, Midwestern State University, Wichita Falls, TX 76308, and WESTROP, Stephen R., Oklahoma Museum of Natural History and School of Geology & Geophysics, Univ of Oklahoma, Norman, OK 73072

Paleoecological studies have shown that certain groups of trilobites demonstrate consistent responses to environmental gradients in a variety of stratigraphic and depositional settings. These associations (biofacies) have recently undergone intense study in the Upper Ordovician, a time period when the Taconic Orogeny was underway in eastern Laurentia. A quantitative study (QxR mode cluster analysis, non-metric multidimensional scaling, rarefaction analysis) of the paleoecological patterns of 1,561 trilobite individuals in 19 Oklahoma collections show that systems tract identity has a strong effect on rarified diversity. Statistically significant differences in diversity are also present across depth gradients in Oklahoma, but comparison with bathymetrically similar deposits in the Taconic Foreland Basin showed similar diversity until the regional extirpation of some trilobite faunas in the late Mohawkian. These data also support several predictions of biofacies/sequence integration, such as rapid shifts in biofacies composition across sequence boundaries. However, TST deposits do not show more rapid vertical shifts in biofacies composition relative to HST deposits as would be expected, likely because of taphonomic effects obscuring the signal. The generally poor preservation of condensed TST grainstone and packestone allowed for the preservation of only robust, convex trilobites (e.g., Failleana, Isotelus).

Paper No. 127-24 - THE ICHNOTAXONOMY OF THE CAMBRIAN SPENCE SHALE OF UTAH: PRELIMINARY RESULTS.

HAMMERSBURG, Sean R.1, HASIOTIS, Stephen T.2, ROBISON, Richard A.2, GUNTHER, Lloyd3, GUNTHER, Val3, and JAMISON, Paul4, (1) Department of Geology, University of Kansas, 1475 Jayhawk Blvd. Room 120, Lawrence, KS 66045-7613, (2) Department of Geology, University of Kansas, 1475 Jayhawk Blvd, 120 Lindley Hall, Lawrence, KS 66045-7613, (3) Brigham City, UT 84302, (4) 371 N 500 W, Logan, UT 84321

The Series 3 Cambrian Spence Shale Member of the Langston Formation is a well-known Lagerstätte that has produced numerous well-preserved trilobites, other arthropods, and soft-body tissues. The Spence Shale is the oldest unit with Burgess Shale-type preservation (BST) from the middle Cambrian of North America. The paleoenvironmental conditions that caused the BST are still unclear. The Spence Shale is a unique BST deposit as it contains BST soft tissues in the same stratigraphic intervals as ichnofossils. Ichnofossils are important tools to help reconstruct ancient environments and can indicate paleoenvironmental conditions during and after deposition as well as the associated paleoecology of a deposit, even when body fossils are absent. Although numerous body fossil studies have been done, an ichnotaxonomic treatment of the Spence Shale has never before been conducted. The Spence Shale is a calcareous shale with intervals of peloidal and oolitic limestone and was deposited on a carbonate ramp on the northwestern edge of Laurentia. To date, eleven ichnogenera have been identified from the Spence Shale: Bergaueria Prantl, Cochlichnus Hitchcock, Cruziana d’Orbigny, Diplichnites Dawson, Didymaulichnus Young, Gyrophyllites Glocker, Monomorphichnus Crimes, Neonereites Seilacher, Planolites Nicholson, Rusophycus Hall, and Treptichnus Miller. Ichnocoenoses will be assigned via the ichnofossil assemblages that are the result of single ecological communities of tracemaking organisms and will be used to understand the interactions and controls on the epi- and endobenthic communities. A currently tentative ichnocoenoses is the Cruziana ichnocoenoses, which includes (in order of abundance) Cruziana, Rusophycus, Planolites, and Treptichnus. The members of the Cruziana ichnocoenoses all occur on a single laminated shale slab with discontinuous laminations of fine-grained carbonate sand. Ichnofacies have yet to be established for the Spence Shale but they will be used to define recurring ichnofossil associations in specific lithofacies. The use of ichnocoenoses and ichnofacies will help delineate environments of deposition, changes in shoreline position, and physicochemical controls including depositional energy, sedimentation rate, and oxygenation.

Paper No. 127-37 - TRILOBITE BIOSTRATIGRAPHY ACROSS THE BASE OF THE WHITEROCKIAN SERIES (ORDOVICIAN) AT ITS TYPE SECTION, WHITEROCK CANYON NARROWS, NEVADA.

LOCH, James, SEPAS (Earth Science), University of Central Missouri, Warrensburg, MO 64093

The Whiterockian Series is the Laurentian expression of the Middle Ordovician Series. The section at the Whiterock Canyon Narrows, Nevada, has been selected as the boundary stratotype with the first appearance (FAD) of the conodont Tripodus combsi defining the base of the series. The nature of the base of the Whiterockian, however, has been controversial with some authors suggesting that the stratotype includes a significant unconformity. Two parallel sections at the stratotype have been sampled for trilobites and conodonts. The lower beds of the underlying Ninemile Formation have yielded Ibexian faunas (trilobite Zone J, the Pseudocybele nasuta trilobite Zone). Trilobites recovered from the Ninemile include Lachnostoma latucelsum, Ptyocephalus declevitus, and P. nasuta (previously recovered from the Ibex region, Utah). Whiterockian faunas (Zone L, the Psephosthenaspis trilobite Zone, the Tripodus combsi conodont Zone), previously documented from the overlying Antelope Valley Limestone, are shown to extend locally into the uppermost Ninemile. In comparison to more continuous section in the Ibex region, Utah, the equivalent of the 2 trilobite subzones in the lower Psephosthenaspis Zone and, possibly, the uppermost interval of the underlying P. nasuta Zone are missing. Contrasts in the distribution of trilobites and conodonts between the 2 parallel sections at the stratotype demonstrate that the unconformity represents the local erosional loss of a minimum of 10m (30 feet) of shale and bedded limestone within the upper Ninemile Formation.

Paper No. 156-5 - A SPECIES ACCUMULATION CURVE FOR TRILOBITA.

ADRAIN, Jonathan M., Department of Geoscience, University of Iowa, 121 Trowbridge Hall, Iowa City, IA 52242, and KARIM, Talia S., University of Colorado Museum of Natural History, 265 UCB, University of Colorado, Boulder, CO 80309

Tabulation of the date of publication of 20,928 trilobite species currently considered valid results in a time series depicting trilobite species accumulation from 1781 to the present. Due to edge effects in tabulating the very recent literature, analysis was based on all publications prior to the end of 2005. A second tabulation documented 5,958 scientific publications whose primary subject was trilobites (or which contained a section primarily concerned with trilobites). The species accumulation curve begins a slow, nearly rate-constant increase around 1838. Rate of species description increased only slightly from then through 1933, with an average of 42 new species a year added during this interval. In 1934, the species accumulation rate began a sustained acceleration, disrupted somewhat by World War Two, with maximum rates of increase seen in the 1970s and 1980s. The curve begins to level off with a clear inflection point after 1983, and species accumulation in recent years (through 2005) reflects a gradually slowing trend (the first period of slowing growth in the systematic history of the group) with the present rate similar to that seen in the 1940s. The curve clearly suggests an asymptote is being approached. One obvious potential explanation for this pattern is the possibility that the pool of easily accessible new trilobite species in the world is approaching saturation. Comparison with the trilobite publication curve, however, suggests a second explanation. The publication accumulation curve agrees well with the species accumulation curve through 1983. After that, the marked rate decline in the species curve is not reflected in the publication curve: trilobite publications have been added at a reasonably steady rate of just under 90 per year since the late 1960s. This suggests that changes in the discipline of paleontology, including shifts away from fundamental systematic research beginning in the 1980s, could be at least partly responsible for the slowing rate of species accumulation. This shift in focus could be due to the declining availability of new species, or possibly to diminishing professional rewards and decreased funding sources for systematic research.

Paper No. 156-7 - CHEMOSTRATIGRAPHY OF THE FURONGIAN (UPPER CAMBRIAN) DEPOSITS OF THE SINO-KOREAN CRATON: INSIGHTS ON GLOBAL CORRELATION AND TRILOBITE EXTINCTIONS.

MCKENZIE, N. Ryan1, GILL, Benjamin C.2, CHEN, Jitao3, PARK, Tae-yoon4, MYROW, Paul M.5, WOO, Jusun4, HUGHES, Nigel C.6, and CHOI, Duck K.7, (1) Department of Geological Sciences, University of Texas at Austin, Austin, TX 78752, (2) Department of Geosciences, Virginia Polytechnic Institute & University, Blacksburg, VA 24061, (3) Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, 39 E Beijing Road, Nanjing, 210008, China, (4) Division of Polar Earth-System Sciences, Korea Polar Research Institute, Incheon, 406-840, South Korea, (5) Department of Geology, Colorado College, Colorado Springs, CO 80903, (6) Department of Earth Sciences, University of California, Riverside, CA 92521, (7) School of Earth and Environmental Sciences, Seoul National University, San 56-1, Sillim, Gwanak-gu, Seoul, 151-742, South Korea

We report a compilation of biostratigraphic data paired with new high-resolution carbonate carbon isotope data from middle to upper Cambrian strata of the Sino-Korean Craton. Within the compilation of trilobite biostratigraphy three Furongian extinction events are recognized, in stratigraphic order, between the Neodrepanura and Chuangia biozones, the Chuangia and Changsahnia/Irvingella biozones, and the Kaolishania and Asioptychaspis/Tsinania biozones. These extinctions appear to be correlative to three extinction events recorded on the Laurentia paleocontinent. The Neodrepanura extinction has been previously correlated with the global end-Marjumid extinction that occurs at the Cambrian Series 3–Furongian boundary at the onset of the Stepteoan Positive Carbon Isotope Excursion (SPICE). The Chuangia extinction is broadly correlative with the end-Steptoean extinction. The Kaolishania extinction is broadly correlative with the end-Sunwaptan extinction and occurs at the onset of a +2‰ δ13C excursion, which is also present in Laurentia. Until now the Steptoean and Sunwaptan extinctions have only been identified in Laurentia and the presence of correlative extinction events on the Sino-Korean Craton suggests they were global in magnitude. Furthermore, the onset of positive δ13C excursions at the Neodrepanura and Kaolishania extinctions suggest a common driver for these events, and the isotope data are consistent with models that postulate episodes of increased oceanic anoxia may have served as the ‘kill-mechanisms’ for these extinctions.

Paper No. 186-5 - THE WEEKS FORMATION LAGERSTATTE (HOUSE RANGE, UTAH): A UNIQUE INSIGHT INTO THE EVOLUTION OF SOFT-BODIED METAZOANS DURING THE LATE CAMBRIAN.

LEROSEY-AUBRIL, Rudy1, GAINES, Robert2, HEGNA, Thomas3, ORTEGA-HERNÁNDEZ, Javier4, BABCOCK, Loren E.5, LEFEBVRE, Bertrand1, KIER, Carlos6, BONINO, Enrico6, SAHRATIAN, Quintin7, and VANNIER, Jean1, (1) Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement (UMR 5276, CNRS), Université Claude Bernard Lyon 1, Campus Scientifique de la Doua Bâtiment GEODE, 2, rue Raphaël Dubois, Villeurbanne, 69622, France, (2) Geology Department, Pomona College, 185 E. 6th St, Claremont, CA 91711, (3) Geology Department, Western Illinois University, 1 University Circle, 113 Tillman Hall, Macomb, IL 61455, (4) Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, United Kingdom, (5) School of Earth Sciences, The Ohio State University, 275 Mendenhall Laboratory, 125 S. Oval Mall, Columbus, OH 43210, (6) Back to the Past Museum, Carretera Cancun, Puerto Morelos, Quintana Roo, 77580, Mexico, (7) Department of Geology and Geophysics, University of Utah, 115 South, 1460, East Room 205, Salt Lake City, UT UT 84112

Cambrian Lagerstätten offer extraordinary insight into the early evolution of metazoans and their organization into complex ecosystems. Recent discoveries in the Ordovician question the traditional view of an abrupt transition between the Cambrian and Paleozoic Evolutionary Faunas. This emerging picture of a more gradual evolution of metazoan communities during the early Paleozoic stresses the need for more data on Cambrian Series 3 to Furongian Series non-biomineralized animals. Here we present some preliminary results of our investigations of the Weeks Formation Konservat-Lagerstätte (Series 3: Guzhangian Stage, Cedaria Zone) of the House Range, Utah. The Weeks Formation comprises a 300-m-thick sequence of thin-bedded lime mudstones, wackestones, and grainstones with variable amounts of shale. It represents an open-shelf marine environment and a late stage in the filling of the House Range Embayment. Two types of exceptional preservation of fossils are recognized in the Weeks Formation: 1, pyritization of major morphological details with subsequent coatings of chlorite and oxidization to iron oxides; and 2, phosphatization of digestive tracts of arthropods. The Weeks Formation yields taxa characteristic of Cambrian Epochs 2-3, but also includes a mix of taxa representative of older and younger Konservat-Lagerstätten. The biota can be considered as a transitional one that lends support to the hypothesis of more gradual evolution of metazoans during the early Paleozoic. The Weeks Formation has yielded a rich trilobite assemblage, abundant inarticulate brachiopods and sponge spicules, and rare hyolithids and echinoderms. The upper Weeks has also produced non-biomineralized and weakly biomineralized organisms. This exceptionally preserved biota is dominated by arthropods and worms (paleoscolescids, priapulids), but it also includes sponges, a possible comb jelly, and other organisms. The arthropod fauna is rich in aglaspidids, a group best known from Guzhangian-Furongian deposits. These are associated with animals characteristic of Cambrian Series 2-3 (Anomalocaris, leanchoiliids) and Ordovician (Tremaglaspis) biotas. The importance of the non-trilobite arthropod fauna is also highlighted by the presence of several species of uncertain affinities.

Paper No. 188-2 - THE CONTROL OF TRUNK SEGMENT DEVELOPMENT IN TRILOBITES.

HUGHES, Nigel C., Department of Earth Sciences, University of California, Riverside, CA 92521, HONG, Paul S., School of Earth and Environmental Sciences, Seoul National University, Seoul, 151747, South Korea, and FUSCO, Giuseppe, Dept. of Biology, Univ of Padova, via Ugo Bassi 58/B, Padova, I-35131, Italy

The good record of trilobite ontogeny offers multiple opportunities to investigate the evolution of development within the clade. The trunk is the postcephalic body region that is constructed postembryonically in almost all trilobites by the sequential release of segments from a subterminal generative zone. In most trilobites the expression of each new exoskeletal segment coincided with an instar, each of which had to be functionally viable as mature form developed progressively. Because all body parts increased in size from instar to instar, and as anterior segments appeared before those that succeeded them, if all segments started at about the same size and shared a similar growth rate, anterior segments are expected to be longer than those succeeding them. Such gradual relative decrease in segment length along the trunk is witnessed in many mature trilobites, and is notable in several iconic Cambrian forms. However, not all trilobites adhered to this pattern, with departures including abrupt changes in segment relative length at particular points along the trunk, regions in which all segments were of similar length, dynamic patterns of changing relative length during ontogeny, and mismatches between axial and pleural segmental growth. In order to begin to explore how such growth patterns are controlled we conducted a detailed analysis of segment relative length during the late meraspid growth of the 429 million year old Aulacopleura koninckii during which the position of the relatively longest trunk segment migrated posteriorly. We explored analytically whether each segment experienced a constant growth rate that was different among segments, or whether segment growth rates were under regional control. Resolving this may have implications for understanding the basal condition of arthropod trunk segment development.

Paper No. 188-3 - THE CAMBRIAN MARINE ARTHROPOD RECORD: EVOLUTIONARY RADIATIONS, MIGRATIONS, EXTINCTIONS, AND EXCEPTIONAL PRESERVATION.

BABCOCK, Loren E., School of Earth Sciences, The Ohio State University, 275 Mendenhall Laboratory, 125 S. Oval Mall, Columbus, OH 43210

Arthropods have held a place of eminence as the most diverse and numerous animals on Earth through nearly the entire Phanerozoic Eon. The roots of that phenomenal success story date to at least the Cambrian Period. Body fossils resembling arthropods are present in some Ediacaran biotas, and certain complex trace fossils close to the Cambrian (Terreneuvian Series) base (541 Ma) may have arthropod tracemakers. The oldest unequivocal arthropod body fossils are in Cambrian Stage 2 (c. 525 Ma). The first trilobites appear in Cambrian Stage 3 (c. 521 Ma), at an early phase in the time during which marine arthropods experienced broad diversification. Most major marine arthropod clades other than decapods make their first stratigraphic appearances in Stage 3 or Stage 4 (521-509 Ma), although to a large extent the apparent distributions of nonbiomineralizing or lightly mineralizing taxa are influenced by preservation in Lagerstätten deposits. Polymerid trilobites and agnostoids, having readily preservable, calcite-reinforced exoskeletons, became the dominant macrofossils of the Cambrian in mid-Stage 4 to Stage 5 (c. 512-509 Ma).
The fossil record of Cambrian arthropods shows a close correlation with variations in carbon and strontium isotopes, and with eustatic sea level history. Major arthropod radiations coincide in time with strong positive δ13C excursions and usually also with positive deflections in 87Sr/86Sr ratios. Mass extinctions coincide with strong positive or negative excursions. Konservat-lagerstätten, most of which are dominated by fossils of nonbiomineralizing arthropods, are overwhelmingly associated with transgressive and highstand systems tracts. Cambrian arthropods provide evidence of glacial-interglacial cyclicity that affected oceanic circulation and influenced the fossil record. In tropical regions, disjunct biofacies of shelf-dwelling trilobites in warm water juxtaposed against cool-water-adapted trilobites in deeper offshore areas implies the presence of a thermocline linked to glaciation in polar Gondwana. Repeated, near-simultaneous migrations of agnostoid species, plus some cool-water-adapted polymerids, onto continental shelves during Cambrian Age 5 to Age 10 coincide with eustatic rises inferred to be associated with interglacial phases.

Paper No. 188-4 - NEW STEM ARTHROPODS FROM THE BURGESS SHALE AND IMPLICATIONS FOR THE MORPHOLOGICAL DISPARITY OF THE "GREAT APPENDAGES".

ARIA, Cédric, Natural History - Palaeobiology, Royal Ontario Museum, 100 Queen's Park, Toronto, ON M5S 2C6, Canada, and CARON, Jean-Bernard, Natural History (Paleobiology Section), Royal Ontario Museum, 100 Queen's Park, Toronto, ON M5S2C6, Canada

Feeding and sensory specialisations are central in the – interlaced – ecological and phylogenetic characterisations of arthropods. This evolutionary drive is within stem-group taxa typified by the variety of forms of the plesiomorphic frontal apparatus known as yet as the "great appendage." Although some of them are usually confounded within the class Megacheira Hou and Bergström, the relationships between all taxa sharing such an appendage are nevertheless obscure, notably because the homology and extent of disparity of this trait remain unresolved. We hereto report, from a new phyllopod bed-like assemblage in Kootenay National Park, Burgess Shale, the discovery of three new Cambrian "megacheiran" arthropods; two of which are bivalved and one leanchoiliid. The leanchoiliid frontal appendage notably presents a pronounced spinose condition in comparison to other described forms, as well as a dense spherical organ within its peduncular portion; the latter trait seems in fact to be widespread in "great appendages" and is possibly diagnostic. Additional evidence exposed by the 41 specimens collected points to a possibly overlooked complexity of cephalic appendages in previous – and smaller – morphotypes, and revigorates the question of crustacean/artiopod affinities within 'pleureomorph megacheirans.' The appendages of the two other, bivalved, morphotypes, are respectively suggestive of plesiomorphic and derived conditions: in one (single specimen), whose bodyplan is very reminiscent of Isoxys Walcott, the general yohoiid aspect of the frontal appendage is associated with Hurdia-like ventral spinose projections (a morphology we associate with a reinterpretation of the frontal appendage in Captopodus poschmanni Kühl and Rust from the Devonian Hunsrück Slate Lagerstätte); in the second (two specimens), the appendage is a 'can opener-like' pseudo-chelicera. Altogether, the appendage morphologies and overall bodyplans of these new bivalved arthropods (1) further support the rooting of yohoiids within stem bivalved taxa, and (2) show the early appearance of a very chelicera-like appendage as part of the Cambrian ecological disparity. In light of this new information, we reevaluate the disparity of the "great appendages" and review phylogenetic scenarii for the radiation of basal euarthropods.

Paper No. 261-7 - THE STRATIGRAPHIC DISTRIBUTION OF THE LATE ORDOVICIAN ‘BUTTER SHALE’ LAGERSTäTTEN IN THE CINCINNATI ARCH REGION.

AUCOIN, Christopher D.1, BRETT, Carlton E.1, THOMKA, James R.2, and MALGIERI, Thomas J.3, (1) Department of Geology, University of Cincinnati, Cincinnati, OH 45221-0013, (2) Department of Geology, University of Cincinnati, 500 Geology-Physics Building, University of Cincinnati, Cincinnati, OH 45221, (3) Department of Geology, University of Cincinnati, 500 Geology/Physics Building, Cincinnati, OH 45221-0013

The Upper Ordovician Cincinnatian strata of Ohio, Kentucky, and Indiana contain multiple claystone units called “butter shales” by local collectors. These shales have long been noted for their abundantly well preserved trilobites, cephalopod, and bivalve fauna. The most well studied butter shale is the Treptoceras duseri shale of the lower Fort Ancient Member of the Waynesville Formation. The Waynesville also hosts at least two or three other claystone units, the Lyrodesma major or Isotelus shale and the newly discovered Oldenburg shale. The slightly older Arnheim Formation contains the Mt Orab butter shale, and the slightly younger Liberty Formation consists of the Minuens shale, named for its unusually small Flexicalymene trilobites, along with some other potentially unnamed trilobite shales. These butter shales may all represent an example of time-specific facies. The change from brachiopod-bryozoan dominated fauna of the surrounding Cincinnatian to the mollusk-trilobite rich fauna of the butter shales indicates an increased rate in sedimentation allowing for mobile organisms to dominate where sessile fauna no longer can. This environment was episodically overwhelmed due to storm events and submarine mud flows, rapidly smothering even the mobile organisms providing the exceptional preservation. The butter shales are also punctuated with lenses of limestone and siltstone, allowing for the return of brachiopods and bryozoans. In contrast, the Moranburg shale of the Maysvillian aged Grant Lake Formation, is dominated by articulated Glyptocrinus and likely represents a time of low sedimentation rate punctuated by rapid sedimentation. The differences in these lagerstätten may be explainable in terms of sequence stratigraphy. Here we present a preliminary comparison of butter shale stratigraphy, paleontology, sedimentology and taphonomy.

Paper No. 262-1 - NEKTASPIDID ARTHROPODS FROM THE EARLY ORDOVICIAN FEZOUATA BIOTA, MOROCCO.

VAN ROY, Peter, Department of Geology and Geophysics, Yale University, PO Box 208109, New Haven, CT 06520-8109

Nektaspidida are an Order of non-biomineralized Early Paleozoic lamellipedian arthropods, which includes the Families Naraoiidae, Liwiidae and Emucarididae. While the appendages of several naraoiid taxa are known in considerable detail, outside of the antennae in Liwia plana, no appendages are known in liwiids, and understanding of the appendage morphology of emucaridids is limited. As a result, Nektaspidida is essentially united on potentially plesiomorphic similarities in dorsal exoskeletal morphology, with all taxa being characterized by the possession of large cephalic and tail shields. In Naraoiidae, no free thoracic tergites are present, while both liwiids and emucaridids exhibit a short thorax comprised of three or four free tergites. Although often regarded as ‘soft-bodied trilobites’, nektaspidids consistently fail to resolve within Trilobita in cladistic analyses; while closely related to trilobites, their exact relationship to this clade currently remains unresolved. In fact, considering the lack of robust synapomorphies uniting Nektaspidida, the possibility that the group itself may not represent a monophyletic clade currently cannot be excluded. Nektaspidids are a rare component of the exceptionally preserved Fezouata Biota from the Early Ordovician of south-eastern Morocco. A small liwiid with an elongate cephalic shield overlapping the first of three trunk tergites and a tail shield of comparable shape but smaller size is known from three different instars. While naraoiids are a typical component of many Cambrian Burgess Shale-type faunas, in the Fezouata Biota they are so far only represented by a single, poorly preserved and incomplete specimen. These new finds add to the scarce Ordovician record of Nektaspidida, which until now was limited to the Middle Ordovician naraoiid Pseudonaraoia hammanni from the Czech Republic and the Late Ordovician liwiids Tariccoia arrusensis from Sardinia and Soomaspis splendida from South Africa.

Paper No. 297-13 - ORDOVICIAN TRILOBITES GETTING UNDER "DINOSAUR SKIN": COMPLEX PRESERVATION OF A MICROBIAL MAT (?) IN OFFSHORE SILICICLASTIC MUDSTONE AND CARBONATE FACIES: KOPE FORMATION (UPPER ORDOVICIAN), KENTON COUNTY, KENTUCKY, USA.

MEYER, David L., Dept of Geology, Univ of Cincinnati, Cincinnati, OH 45221, BRETT, Carlton, Department of Geology, Univ of Cincinnati, 500 Geology/Physics Bldg, Cincinnati, OH 45221-0013, DATTILO, Benjamin, Department of Geosciences, Indiana University Purdue University Fort Wayne, 2101 E. Coliseum Blvd, Fort Wayne, IN 46805-1499, and FINE, Ron, Department of Geology, Univ of Cincinnati, OH 45221

Unusual preservation of small primaspid trilobites may provide a key to the first recognition of a microbially induced sedimentary structure in the subtidal U. Ordovician Kope Fm. of northern Kentucky. A thin, elliptical lens of silty mudstone (2 m long, at least 1 m wide, and up to 3 cm thick) in the lower Kope Formation (Pioneer Valley Submember, McMicken Member, C-1 Sequence) has several unique features mainly restricted to its basal surface. Toward one end the basal surface has parallel-fluting that terminates in a complex of conjoined, flattened, ellipsoidal or spatulate concretion-like lobes at the other end. The entire basal surface has small-scale wrinkles or corrugation (3-4 mm wide) variably developed. Articulated carapaces of small, spinose primaspid trilobites (Primaspis crosota) occur with their ventral surfaces applied directly to the wrinkled surfaces (i.e. dorsal-side-down). The wrinkled texture of the basal surface is aligned with the minor axis of the elliptical lobes and can wrap around to their upper surfaces. At the rounded ends of the lobes the wrinkling becomes reticulated by crosscutting of wrinkle sets. In the same region the reticulate undersurface is covered with minute rounded pustules (~0.3 mm). Other Cincinnatian occurrences of primaspids on undersurfaces of bryozoans and brachiopods suggest a cryptic life habit for purposes of feeding or shelter. This habit, together with the wrinkled, reticulate and pustulose undersurface suggest that a cohesive membrane or mat, most likely of microbial origin, was smothered by sediment influx triggered by storm or seismic disturbance. Evidence of the mat is preserved as an impression in hyporelief, like some dinosaur skin. Loading and lateral shifting of the sediment-laden mat resulted in wrinkling, trapping of fluid sediment, and convolution of boudinage-like lobes. As an alternative, the lobate structures suggest infilling of a 3D, sacklike organism (?) flattened by compaction, with "wrapping" of the corrugation onto the upper as well as basal surface. Whatever the origin, the unique combination of features reported here has never before been found in the Kope Fm., a subtidal lithofacies that has received intense scrutiny.

Paper No. 300-7 - A NEW ‘PHYLLOPOD BED’-LIKE ASSEMBLAGE FROM THE BURGESS SHALE: STRATIGRAPHIC SETTING AND THE CATHEDRAL ESCARPMENT IN KOOTENAY NATIONAL PARK.

GAINES, Robert R., Geology Department, Pomona College, 185 E. Sixth Street, Claremont, CA 91711, CARON, Jean-Bernard, Natural History (Paleobiology Section), Royal Ontario Museum, 100 Queen's Park, Toronto, ON M5S2C6, Canada, and STRENG, Michael, Department of Earth Sciences, Uppsala University, Norbyvägen, 22, 75236, Sweden

The Burgess Shale fauna is best known from Walcott’s Quarry on Fossil Ridge. Here, and at several other localities in the vicinity of Field, British Columbia, the Stephen Formation lies in direct contact with the Cathedral Escarpment, a prominent submarine cliff. A new Burgess Shale locality, discovered in 2012 in Kootenay National Park ca. 40 km southeast of the type area, contains a rich ‘phyllopod bed’ like assemblage in the uppermost Stephen Formation. Local stratigraphy indicates that the locality was situated immediately offshore of a major topographic break, and lies <400 m from the classical ‘thin’ Stephen Formation, yet is distinguished by a significantly greater thickness and fundamental differences in cycle architecture. The ‘thin’ Stephen in the study area is ~35 m thick and conformably overlies cryptalgal laminate, whereas the basinal Stephen Formation is ~140 m thick and is separated from the underlying Cathedral Formation by a megatruncation surface interpreted to represent platform margin collapse. The ‘thin’ Stephen locally is typical of the Yoho-Kootenay region and is characterized by shale-packstone depostional cycles 3-5 m thickness with amalgamated tops. In contrast, the basinal Stephen Formation contains shale – carbonate mudstone depositional cycles 20 -30 m in thickness with no evidence of condensation or reworking at cycle tops. The basinal Stephen Formation at the new locality contains pervasive syn-sedimentary slumps and slide dislocations ranging from 0.1 to 3 m in thickness, indicating significant slope of the depositional surface. The markedly reduced thickness of this section compared to that of the Stephen Formation in the vicinity of Fossil Ridge (>300 m) may represent: 1. A previously unrecognized transitional expression of the Stephen Formation that lay offshore of a topographic break, but was deposited on a steep slope rather than at the toe of an escarpment; 2. Differential subsidence/accommodation space, or; 3. Diachronous platform margin collapse during deposition of the Stephen Formation regionally. The new assemblage underscores the importance of the Cathedral Escarpment to the preservation of the richest fossil assemblages, specifically in facilitating rapid downslope transportation of fossils and fine sediments en masse across chemical gradients.

Paper No. 376-3 - LOWER SILURIAN CONODONTS AND TRILOBITES FROM THE GOBI ALTAI-MANDALOVOO TERRANE, SOUTHERN MONGOLIA.

DANIELSEN, Erika, Geological Sciences, SUNY-Geneseo, Geneseo, NY 14454, OVER, D. Jeffrey, Geological Sciences, S.U.N.Y. Geneseo, Geneseo, NY 14454-1401, SULLIVAN, Nicholas, Wisconsin Geological and Natural History Survey, Madison, WI 53705, SMITH, Dana Marion, Department of Geoscience, University of Wisconsin, Madison, WI 53706, MINJIN, Chuluun, Research Center for Stratigraphy and Paleontology, Mongolian University of Science and Technology, Ulaanbaatar, Mongolia, MYROW, Paul M., Department of Geology, Colorado College, Colorado Springs, CO 80903, and SOJA, Constance M., Geology, Colgate Univ, 13 Oak Drive, Hamilton, NY 13346

Mongolia is a collage of 44 terranes that accreted throughout the Paleozoic and Mesozoic. This complex coalition of distinct geologic units has made it challenging to decipher the geologic history of the region. To better understand the geologic events that formed Mongolia this study focused on constraining the ages of two formations in the Gobi Altai-Mandalovoo Terrane near Yamaan Us in the Shine Jinst area of southwestern Mongolia. Conodonts and trilobites were recovered from the upper Zalaa and lower Sharchuluut formations from a 60 meter interval across the contact. The Zalaa Formation consists largely of shale with numerous thin fossiliferous trilobite-rich limestone beds in the uppermost portion. The Sharchuluut Formation is mainly crinoidal limestone and siltstones considered early to mid-Silurian based on brachiopod and coral remains. 34 samples horizons were examined for macrofossils and five were found to contain Proetidae trilobites. 20 samples were processed for conodonts and eleven produced identifiable elements. The conodonts Aspelundia expansa, Distomodus kentuckyensis, and Ozarkodina hassi indicate the upper Zalaa Formation and the lower Sharchuluut Formation are lowest Silurian assignable to the expansa Zone. These cosmopolitan conodonts indicate placement of the Gobi Altai – Mandalovoo Terrane in a tropical realm with open sea circulation during the Early Silurian.

Paper No. 394-5 - ACTIVE LEARNING UNDERGRADUATE FIELD TRIP TO THE BURGESS SHALE, BRITISH COLUMBIA, CANADA.

ANDERSON, Thomas B., Geology, Sonoma State University, 1801 East Cotati Avenue, Rohnert Park, CA 94928, and JAMES, Matthew J., Geology, Sonoma State University, 1801 E Cotati Ave, Rohnert Park, CA 94928-3609

The Cambrian Burgess Shale lagerstatten localities in British Columbia have been a successful field trip destination from the Department of Geology at Sonoma State University since 2003. The Walcott Quarry and the Mount Stephen Fossil Beds are reached on guided hikes by the Burgess Shale Geoscience Foundation (BSGF) or Parks Canada. A UNESCO World Heritage site since 1981, collecting is forbidden. During the hikes, knowledgeable guides make stops to describe the history, paleontology, stratigraphic significance, and tectonic context. Field trip base and accommodations are in Field, BC. The Walcott Quarry, discovered by C.D. Walcott in 1909, and excavated by him during the next several years, is reached by a 20 km round trip hike with 760 m of vertical climb. Abundant fossils, including soft-bodied forms, make the Burgess Shale unique. At the quarry, well-preserved fossil specimens are displayed with drawings of reconstructions. The Mount Stephen Fossil Beds were discovered by R.G. McConnell in 1886 after a railroad worker, Otto Klotz, found “stone bugs” (trilobites) during construction of the trans-Canada rail line. These beds are rich in trilobites and Anomalocaris grasping claws. The Mount Stephen hike is shorter (6 km round trip) with the same vertical component. The fieldwork is the precursor to a semester-long class at Sonoma State University. After the August field trip, students meet for the Fall Semester and research the taxonomic history of a particular fossil genus. Enthusiastically received by students, class evaluations have been very favorable. In 2009, the centennial of Walcott’s discovery, we conducted the trip for seven college professors under the rubric of the International Paleontological Research Exchange Program of the BSGF. Student educational benefits are numerous. Students, in a spectacular setting, learn fossil history, paleontology, and are exposed to numerous questions still being debated including the depositional environments, preservation mode, evolution of body parts, and the Cambrian explosion. Comparative stratigraphy is used to contrast the Burgess Shale to our usual field trips in Cambrian rocks near Death Valley. A hike on the Athabasca Glacier and a stop at the Royal Tyrrell Museum and its exceptional displays including a Burgess Shale section are added benefits.

Paper No. 403-3 - THE DEVELOPING GLOBAL CHRONOSTRATIGRAPHIC SCALE FOR THE CAMBRIAN SYSTEM AND ITS IMPACT ON NORTH AMERICAN STRATIGRAPHY.

BABCOCK, Loren E., School of Earth Sciences, The Ohio State University, 275 Mendenhall Laboratory, 125 S. Oval Mall, Columbus, OH 43210, PENG, Shanchi, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing, 210008, China, and ROBISON, Richard A., Department of Geology, University of Kansas, 1475 Jayhawk Blvd, 120 Lindley Hall, Lawrence, KS 66045-7613

The definition of GSSPs bounding and within the Cambrian System have profoundly altered concepts of the system as applied in North America. C. D. Walcott’s (1890) definition of the Cambrian base at the Olenellus Zone has been superseded by ratification of the Cambrian base at a horizon coinciding with the appearance of the trace fossil Treptichnus pedum. This decision essentially doubled the length of the Cambrian Period and automatically redefined as Cambrian a long succession of pre-trilobitic stratigraphy previously considered Proterozoic. Ratification of the base of the Ordovician System at a horizon above the base of the Ibexian Series of North America added stratigraphic thickness to the Cambrian that was formerly considered to be Ordovician. Historically, two sets of nomenclature have been used for regional series and stages of the Cambrian on the Laurentian paleocontinent. Stage and series definitions were based on polymerid trilobite or agnostoid biozones or, alternatively, the absence of trilobites. One set of definitions was developed in restricted inner-shelf facies, and the other set was developed in more open, outer-shelf facies. Common separation of these facies belts by carbonate platform deposits led to the evolution of separate trilobite biofacies. Few taxa in common between the inner and outer shelf regions rendered it difficult to precisely correlate across the continent using trilobite biostratigraphy alone. Imprecise or differing interpretations of boundary positions led to further ambiguity of stratigraphic positions within the North American Cambrian. The International Subcommission on Cambrian Stratigraphy has recommended a global chronostratigraphic subdivision of the Cambrian that comprises four series and 10 stages, of which half have so far been defined by GSSPs. Internal subdivisions of the Cambrian System adopted globally bear little resemblance to the historical sets of regional nomenclature used in North America. The global chronostratigraphic subdivisions, however, have the advantage of being unambiguous and traceable outside the Laurentian paleocontinent. Using a combination of chronostratigraphic methods it is now possible to overcome the historic impediments to correlation across separate facies belts of Laurentia.

Paper No. 407-7 - RIDING THE WAVES: FEEDING HABITS OF TRIARTHRUS BECKII AND ITS ALIGNED CRUZIANA IN A LATERALLY EXTENSIVE TRACE-FOSSIL EVENT BED IN THE UTICA SHALE, NEW YORK STATE.

BOYER, Diana L., Earth Sciences, SUNY Oswego, 241 Shineman Science Center, Oswego, NY 13126, and MITCHELL, Charles E., Geology, University at Buffalo, SUNY, Buffalo, NY 14260

The olenid trilobite Triarthrus is one of the rare macrofossils commonly present in the nearly barren black shales of the Late Ordovician Utica Formation. Triarthrus paleoecology and mode of feeding are uncertain. Some previous authors have suggested that this olenid, in part because of its proclivity for deep water dysoxic facies, harbored sulfur-reducing chemosymbionts. A laterally extensive (~15 km) trace fossil event bed in the Indian Castle Member of the Utica Formation, central New York State, preserves abundant Rusophycus and Cruziana along with T. beckii body fossils (both molts and carcasses). Carcasses are rare but trace fossil densities are 10-20/100 cm2. The only other fossils on this surface are orthoconic nautiloids and graptolites. The event bed surface is directly overlain by an ~10 cm-thick ash beds that evidently smothered the surface and thus provides a unique glimpse at the paleoecology of these trilobites. Orientation of over 500 individually measured traces reveals strong alignment with heads facing directly into the current, which flowed from the WSW toward the ENE (supported by aligned nautiloids). Traces grade from Rusophycus into Cruziana with the latter type strongly dominant. Rusophycus specimens resemble the size and shape of Triarthrus beckii. These data suggest that T. beckii were not farming chemosymbionts, but rather were particle feeders that in this instance employed the weak regional current to assist feeding under quiet and strongly dysoxic conditions. These results support recent findings for Triarthrus eatoni at Beecher’s Trilobite Bed and other aligned occurrences of Cruziana and Rusophycus.

[piranha]

The GSA 125Th Anniversary meeting features a record-shattering 4,900 abstracts!

If anyone from TFF is planning to attend please report back with details and photos.

[AgrilusHunter]

Yeah, I would very much like to attend this one:

THE ORIGIN AND EARLY EVOLUTION OF LEAF-MINING INSECTS IN THE WAKE OF THE END-PERMIAN ECOLOGICAL CRISIS

LABANDEIRA, Conrad C., Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013-7012, labandec@si.edu, PREVEC, Rose, Albany Museum, Rhodes University, Grahamstown, 6410, South Africa, ANDERSON, John M., Bernard Price Institute for Palaeontological Research, University of the Witwatersrand, Johannesburg, 2050, South Africa, SANTIAGO-BLAY, Jorge, Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013, DAVIS, Don, Entomology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013, ANDERSON, Heidi M., Bernard Price Institute for Palaeontological Research, University of the Witwatersrand, Johannesburg, 2050, South Africa, and CURRANO, Ellen D., Department of Geology and Environmental Earth Science, Miami University, 114 Shideler Hall, Oxford, OH 45056

A major consequence of the end-Permian (P-Tr) ecological crisis was extensive reorganization of terrestrial ecosystems and accompanying taxonoic turnover that resulted in extinction of many plant and insect lineages. The feeding relationships between insects and plants was a major victim of this profound transition, and included several types of feeding interactions that regionally were extirpated but subsequently re-evolved during the ensuing Triassic. For the Karoo Basin P-Tr sequence in South Africa, the abundance and diversity of Permian plant-insect interactions dramatically declined, and included extirpation of many external foliage feeding, piercing and sucking, oviposition and galling damage types (DTs). Until recently, leaf mining was not thought to occur during the Permian. Current evidence indicates that leaf mining was present in one latest Permian site in Kwa Zulu-Natal (Kwa Yaya), represented by a distinctive blotch mine on a particular glossopterid leaf morphotype. Although this mine type, and its plant host, did not survive the P-Tr event, leaf mining re-evolved, probably twice, during the Middle Triassic in Gondwana. For the Karoo Basin, two groups of Late Triassic leaf mines, collectively assignable to eight DTs, have been recorded on a broad spectrum of vascular plants. the first group represents robust, long, linear mines with sinusoidal frass trails that excavate most of the mesophyll layer and are very similar to modern polyphagan beetle mines. These mines occur in the foliage of woody seed-plant hosts of conifers (Heidiphyllum), cycads (Pseudoctenis), three major lineages of ginkgophytes (Paraginkgo, Sphenobaiera, Dejerseya), corystosperms or umkomsialeans (Dicroidium), and an unaffiliated taxon (Linguifolium). The second group is gracile, short, abbreviated mines with mostly linear frass trails typically lodged in the epidermis of nonwoody hosts, and resemble the mines of basal moth lineages. This latter group of mines occurs in the nodal zones of horesetails (Equisetites), pinnules and rachises of ferns (Cladophlebis), and leaves of the herbaceous ginkgophyte Kannaskoppifolia. There probably were two, parallel diversification events of leaf-mining insect lineages, each targeting a different plant physiognomy within the Molteno Biota.

<sigh> Maybe next year.

[hamme1sr]

Don't forget to stop at this poster! The IchnoBioGeoScience (IBGS) Research Group at the University of Kansas is compiling the largest online repository of trace fossils. It is our goal to get a complete and up-to-date synthesis on Ichnology as well as complete listing of all known and valid ichnotaxa online for easy access to students, educators, oil industry workers, and professional and amateur paleontologists!

Be sure to stop by our website: http://ichnology.ku.edu/

FROM ABELICHNUS TO ZOOPHYCOS: AN ONLINE CATALOGUE OF ICHNOTAXA

CONNOLLY, Andrew M., Department of Geology, University of Kansas, Lawrence, 66045, andrewco@ku.edu, GOLAB, James A., Geology and Geological Engineering, Colorado School of Mines, 1516 Illinois Street, Golden, CO 80401, WOLFE, Benjamin A., Department of Natural Sciences, Metropolitan Community College-Blue River, 20301 E. 78 Highway, Independence, MO 64057, WILDERMUTH, Sarah, Department of Geology, University of Kansas, Lawrence, KS 66046, HAMMERSBURG, Sean R., Department of Geology, University of Kansas, 2408 Alabama St. C10, Lawrence, KS 66046, DZENOWSKI, Nicole, Department of Geology, University of Kansas, 1475 Jayhawk Blvd. Room 120, Lawrence, KS 66045-7594, RAISANEN, Derek C.W., Geology, Universit of Kansas, Lindley Hall, 1475 Jayhawk Blvd. Room 120, Lawrence, KS 66045-7594, SCHMERGE, Joshua, Department of Geology, The University of Kansas, 1475 Jayhawk Blvd. Room. 120, Lawrence, KS 66045, FALK, Amanda R., Geology, University of Kansas, 1475 Jayhawk Blvd, 120 Lindley Hall, Lawrence, KS 66045-7613, and HASIOTIS, Stephen T., Department of Geology, University of Kansas, 1475 Jayhawk Blvd, 120 Lindley Hall, Lawrence, KS 66045-7613

The last Treatise on Invertebrate Paleontology dealing with Ichnotaxonomy—Part W (Revised and Enlarged) Miscellanea, Supplement 1, Trace Fossils and Problematica—was published in 1975. Since then, no publication(s) compiling and evaluating all known invertebrate ichnotaxa into one source has been produced, and no one has ever compiled all known vertebrate ichnotaxa into one source. The IchnoBioGeoScience (IBGS) Research Group at the University of Kansas, Geology Department, seeks to accomplish these tasks. A catalogue of ichnotaxa is provided online at our website, www.ichnology.ku.edu, which is currently under construction. This is an evergreen project–­–to be updated continuously––that is open to input from anyone with interest in ichnology and organismal behavior. Ichnotaxa will be organized in alphabetical order and subdivided by interpreted tracemaker: microbial, plant, invertebrates, and vertebrates––fish, amphibians, nondinosaurian reptiles, dinosaurs, birds, and mammals (including therapsids). All ichnotaxa will have the following information: name; reference that erected the ichnotaxon; any junior synonym(s) that may be a part of the ichnotaxon; geologic range; description; interpreted behavior; environment(s) in which it is found; possible tracemaker(s); and additional references, including references that emend the ichnotaxon. Each ichnotaxon will be illustrated with one or more images as photographs and/or line drawings. The website also has individual pages tailored to particular concepts in ichnology and related materials, including: 1) an introduction to ichnology; 2) ichnocoenoses and ichnofacies models; 3) tiering and ichnofabrics; 4) a glossary; 5) videos, anaglyphs, and animations; 6) references to modern and ancient tracemaking organisms; and 7) links to other ichnological websites. The main objective of the KU ichnology website is to provide access and awareness of ancient and modern behavioral information to the general public, as well as to educational institutions of lower (i.e., K–12) and higher (i.e., collegiate) learning. For example, videos of modern burrowing behaviors and neoichnological experiments (e.g., ant farms) can be used in the classroom to help students learn about organism behavior and the hidden biodiversity that exists below their feet.