NAPC 2001

June 26 - July 1 2001 Berkeley, California

Abstracts, Di - Fa

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DIETL, Gregory P., Dept. of Zoology, North Carolina State University, Raleigh, NC, USA; Richard R. Alexander, Dept. of Geological and Marine Sciences, Rider University, Lawrenceville, NJ, USA; Patricia H. Kelley, Dept. of Earth Sciences, University of North Carolina at Wilmington, Wilmington, NC, USA; and Thor A. Hansen, Dept. of Geology, Western Washington University, Bellingham, WA, USA

Previous studies have tested for stereotypy of naticid drillholes on bivalve shells by using Goodness-of-Fit tests, which are increasingly conservative with decreasing sample sizes. Alternatively, borehole distribution among nine valve-sectors of each species can be analyzed by the Shannon-Weaver diversity index, H'= -Sigma pilnpi, which is sensitive to evenness of abundances. J is the ratio of H' to Hmax, the value that would result if boreholes were evenly distributed among all sectors. J varies between 0 (all boreholes in one sector; maximum stereotypy) and 1 (boreholes evenly divided among all nine sectors; minimum stereotypy). J was calculated for 119 bivalve species of Cretaceous to Recent age from the Atlantic coastal plain; stereotypy decreased from the Cretaceous (mean J=0.61) to the Miocene (0.83) and then increased to the Recent (0.39). ANOVA indicates significant decreases in stereotypy from the Cretaceous to Eocene and increases from the Miocene to Pliocene and Pleistocene to Recent. Whereas venerids show stasis, mactrids, astartids, glycymerids, lucinids, and corbulids show increasing stereotypy, with corresponding significant (r=0.56; p <0.003) decrease in drilling frequencies and insignificant (r=0.19; p=0.20) increase in drilling success (reduced prey effectiveness) from the Cretaceous to the Recent. Coarsely ornamented species have significantly higher stereotypy
(mean J=0.63) than unornamented species (mean J=0.78)(ANOVA). J values correlate inversely with valve area for Recent bivalves (p <0.05), but show no apparent relationship to prey shape through time. Recent bivalves show no significant Spearman rank correlation between J-values and habit (epifaunal to deep burrower), habitat (intertidal to subtidal), and burrowing rate index, although combinations of these factors, plus shape and size, may differentiate naticid stereotypy through geologic time. Post-Miocene increased naticid efficiency suggests that bivalves have possibly reached (temporary) adaptive limitations to this predator.


DILLHOFF, Richard M., and Estella B. Leopold, University of Washington, Seattle, WA, USA; and Steven R. Manchester, Florida Museum of Natural History, Gainesville, FL, USA

The concept of an Okanogan Highlands flora has come into common usage to describe as many as six roughly co-eval Middle Eocene lacustrine floras extending from Northern Central Washington into Central British Columbia. While early publications exist for the Eocene localities of British Columbia, only Republic and Princeton have recent, detailed floral descriptions on which to base comparisons. We have begun a comprehensive investigation of the McAbee site, near Kamloops, British Columbia. Megafossils and pollen are used to infer climate and compare the flora found at the McAbee site to that at Republic and Princeton as well as approximately co-eval lowland assemblages in the Puget Group and Chuckanut formations. Conifers are common and diverse at McAbee, with at least twelve separate taxa present. There are also at least twenty-two angiosperm genera with many yet to be described. The dominant dicot leaf taxon at McAbee is Fagus, which is also represented by nuts and cupules. The confirmation of Fagus, also recognized from Princeton and Republic, provides the oldest well-documented occurrence of the genus, predating the early Oligocene records of Fagus previously reported for North America, Asia and Europe. McAbee apparently lacks thermophilic elements such as Sabal, found at Princeton or Ensete and Dioon found at Republic. It also appears to lack the diversity seen at Republic, although this may be an artifact of the intensive public collecting done there in recent years. In summary, the McAbee site appears to be a good fit overall for the Okanogan Highlands floral construct but also has unique elements that expand our knowledge of the Middle Eocene flora of the Pacific Northwest.


DORNBOS, Stephen Q., and David J. Bottjer, Dept. of Earth Sciences, University of Southern California, Los Angeles, CA, USA

As the depth and intensity of bioturbation increased through the Proterozoic-Phanerozoic transition, the substrates on which marine benthos lived changed from being relatively firm with a sharp sediment-water interface to having a high water content and blurry sediment-water interface. Microbial mats, once dominant on normal marine Proterozoic seafloors, were relegated to stressed settings lacking intense metazoan activity. This change in substrates has been termed the agronomic revolution (Seilacher and Pflüger, 1994), and the impact of this substrate transition on benthic metazoans has been termed the Cambrian substrate revolution (Bottjer et al., 2000). Because the Early Cambrian was a transitional time in this substrate revolution, benthic metazoans adapted to typical Proterozoic-style soft substrates might have co-existed with benthic metazoans adapted to more typical Phanerozoic-style soft substrates. Paleoecological examination of the Early Cambrian Chengjiang fauna is perhaps the ideal way to begin testing for this co-existence. Suspension feeders well-adapted for survival on typical Proterozoic-style soft substrates are characterized by small size and a sediment-resting or shallow sediment-sticking lifestyle and include, for example, the enigmatic Chengjiang suspension feeder Dinomischus, a shallow sediment sticker. Suspension feeders well-adapted to typical Phanerozoic-style soft substrates are characterized by attachment abilities, root-like holdfasts, broad body mass distribution, or deep sediment-sticking. Examples from the Chengjiang fauna include the suspension feeding cnidarian Cambrorhytium, which lived attached to available hard substrates. Mobile benthic metazoans of the Chengjiang fauna also show adaptations to both substrate styles. Thus, instead of being simply early evolutionary experiments, some Cambrian benthic metazoans with seemingly unusual morphologies were actually just well-adapted for survival on non-actualistic microbial-mat-bound soft substrates typical of the Proterozoic.


DROSER, Mary L., and Sören Jensen, Dept. of Earth Sciences, University of California, Riverside, CA, USA; James G. Gehling, South Australian Museum, Adelaide, Australia; Paul M. Myrow, Dept. Of Geology, The Colorado College, Colorado Springs, CO, USA; and Guy M. Narbonne, Dept. of Geological Sciences, Queen's University, Kingston, ON, Canada

Bioturbation has long been "blamed" for eliminating late Proterozoic-style sedimentary structures and fabrics. While the presence of diverse and complex burrows in lowermost Cambrian strata is indisputable, analysis of Lower Cambrian successions in Newfoundland demonstrate that this burrowing did not produce Phanerozoic-style ichnofabrics. We examined 300 meters of the siltstone/sandstone facies of member 2 of the Chapel Island Formation in the area of the Precambrian-Cambrian boundary stratotype. Gyrolithes, Planolites, and Skolithos occur as sand infills ubiquitously throughout siltstone beds, most commonly without direct contact with an overlying sandstone bed. In contrast, Treptichnus pedum occurs as sand infills adhering onto the base of thin sandstone beds that have different grain size and texture than the burrow infills. Both of these burrow types represent a style of preservation in which the burrows are unattached to an overlying bed of the casting sediment. These styles of preservation occur frequently in the Treptichnus pedum Zone and continue into the Rusophycus avalonensis Zone in spite of an increase in trace fossil diversity. The sandstone beds are only very rarely bioturbated and there is no evidence of mat structures. The resultant fabric produced by floating and, in particular, adhering burrows in these shallow marine deposits, appears to be characteristic of the Lower Cambrian and uncommon in younger rocks. This kind of preservation also occurs in the Lower Cambrian Wood Canyon Formation of the Western US and the Mickwitzia sandstone of Sweden. Silt layers appear to have been firm enough to have supported open burrows. Evidence suggests that in spite of an increase in trace fossils diversity and complexity, there was not extensive bioturbation and mixing during the earliest Cambrian.


EBERLE, Jaelyn, Canadian Museum of Nature, Ottawa, ON, Canada; John Storer, Yukon Dept. of Tourism, Heritage Branch, Whitehorse, YK, Canada; Karen Chin, Dept. of Geological and Environmental Sciences, Stanford University, Stanford, CA, USA; and Stephen Cumbaa, Canadian Museum of Nature, Ottawa, ON, Canada

We report a newly discovered marine fauna from Late Cretaceous strata infilling Eidsbotn graben, a small northeast-trending structure on Colin Archer Peninsula, NE Devon Island, Nunavut Territory, Canada. At the six known localities, fossils were found primarily weathering out of green, glauconitic sandstones that belong to a unit correlative to the Kanguk Formation. A diverse vertebrate fauna is represented by fossils of shark, bony fish, plesiosaur, and a probable crocodilomorph. Specifically, at least three chondrichthyans, including two lamniform sharks of the family Cretoxyrhinidae and a ratfish, and at least two bony fishes, including Enchodus and an unidentified percomorph, are reported. Additionally, fossils of a very large fish with a distinctive surface ornamentation of isolated bumps or ossicles on its skull bones may represent either a Lepidotes-like semionotiform or a coelacanth. At least one plesiosaur taxon is known from vertebrae, limb fragments, and teeth, and the probable crocodilomorph is represented by thick, bony skutes. The scales of the percomorph fish, with clear evidence of annulus formation, indicate warm-temperate water temperatures, as does the crocodilomorph.

Amongst fossil invertebrates, the brachiopod Lingula, probable rhyncholites (i.e., nautiloid or "squid" beaks), and fossils of crayfish (isolated appendages and a few relatively complete skeletons) are locally abundant. Additionally, a high concentration of coprolites, ranging in size from a few centimeters (common) to a third of a meter (rare), was discovered at one locality. While we cannot be sure of their producer, it is evident that the coprolites were formed by fish and/or aquatic reptiles.

Fossils from Eidsbotn graben provide a window into a diverse, high-latitude marine community inhabiting warm-temperate ocean waters during Late Cretaceous time. Further analyses of the fauna will refine the age of the strata as well as the paleoenvironment, and provide insight into the paleobiology of its organisms.


EDELMAN-FURSTENBERG, Yael, Dept. of Geophysical Sciences, University of Chicago, Chicago, IL, USA, and Geological Survey of Israel, Jerusalem, Israel; Susan M. Kidwell, Dept. of Geophysical Sciences, University of Chicago, Chicago, IL, USA; and Ahuva Almogi-Labin and Zeev Lewy, Geological Survey of Israel, Jerusalem, Israel

The factors governing the deposition of sediments rich in silica, organic carbon, and phosphorite in high-productivity marine settings are complex, and many fundamental questions remain unanswered for both modern and ancient examples. The primary aim of this project is to explore macrobenthic paleontologic evidence for bottom-water conditions across a Cretaceous high-productivity tract in Israel, especially bottom oxygen levels. To establish a regional paleoecological reconstruction, we described and sampled a paleo-high, paleo-low and three paleo-intermediate sections of the Upper Campanian Mishash Formation of southern Israel, three of them in detail. During this work, we discovered both a fine- and coarse scaled cyclicity. Fossil-rich beds are stratigraphicaly positioned at the boundary of the small-cycles. An upward trend of coarsening grain size, increasing abundance of fossil remains and higher degree of shell packing were detected along such a cycle. This seems to follow a change in the environmental settings, specifically an increase in bottom oxygen content and bottom water energy.

Pollution studies in modern environments have demonstrated the close connection between stressful conditions (organic load, toxicity, water and sediment aeration) and benthic community structure, as expressed through species richness, evenness, taxonomic composition, body sizes, and trace fossil assemblages. We investigated these trends and behavior patterns in the varied benthic fossil assemblages of the Mishash Formation. Macrofauna (dominantly bivalve and gastropod mollusks) are present in virtually all rock types but in varying abundance and taxonomic compositions, changing from diverse assemblages (~20 species) to mono-specific ones to barren intervals. Combined with benthic microfossil and lithologic information from the same sites, all collected within a sequence stratigraphic context, the project exploits multiple independent lines of evidence for ancient bottom-water conditions.


EICKS, Patricia A., Nicholas A. Angeli, and Bruce L. Stinchcomb, Dept. of Geology, St. Louis Community College at Florissant Valley, St. Louis, MO, USA

Matthevia is a type of plated mollusk characterized by valves with two tapering pockets and a massively subconical shell. This fossil mollusk was first recognized and described by Charles D. Walcott in 1885 from the Upper Cambrian Hoyt Limestone of northern New York. A form of Matthevia occurs in cherts of the Eminence Formation of Uppermost Cambrian age in the Ozark Uplift of Missouri.

The Missouri specimens differ from Walcott's Matthevia variabilis in being bilaterally symmetrical. Specimens from the Hoyt Limestone, in contrast, while exhibiting two pockets, are usually asymmetrical as one pocket is larger than the other. Missouri specimens from the Eminence Formation consistently have both pockets of equal size. Runnigar, Pojeta et. al. 1979, describe a new species of Matthevia, M. walcotti. They consider Matthevia to be an early and primitive amphinuran, and as such it would have had eight valves when living. In Matthevia walcotti the two pockets are quite different both in size and length, with one pocket barely being present. M. walcotti more closely resembles specimens of Hemithecella, a plated mollusk with one pocket or posterior tunnel. Yochelson 1966, describes Matthevia as a new molluscan class, having two massive alcareous plates, one anterior and one posterior, with growth lines and bilateral symmetry.

Valves of Matthevia may occur clustered together, as is the case with other plated mollusks, however articulated eight valved specimens, suggesting affinity with the amphinurans, have not been found. Suggestions have been made that Matthevia might be a monoplacophoran as it is associated with an extensive monoplacophoran fauna. Specimens found so far lack evidence of muscle scars, and considering the distinct morphology of Matthevia cannot be considered as such.


EKDALE, A.A., Dept. of Geology and Geophysics, University of Utah, Salt Lake City, UT, USA

Substrate character directly affects burrowing behavior and influences burrow morphology. Thalassinoides and similar large, branched or anastomosed burrow systems are generally regarded as deep-tier, fodinichnial traces of deposit-feeding arthropods, especially decapod crustaceans, which can excavate burrows in a wide spectrum of substrate types. Burrow morphologies and branching geometries vary in response to substrate heterogeneities, including both unconsolidated sediment and cemented rock. The size and shape of tunnels in the same burrow system will differ significantly in soupground, softground, firmground and hardground situations that are encountered by the burrower at different depths below the water-sediment interface. A single trace fossil may exhibit a composite of highly compacted burrows, idiomorphic burrows, stenomorphic burrows and even borings that were excavated by the same animals.

Substrate-controlled morphologies and geometries in composite Thalassinoides (sensu lato) abound in Phanerozoic carbonate sequences. In Cambrian algae-rich limestones in Utah, Thalassinoides geometries are constrained by stromatolite growth. In Ordovician thin-bedded limestones in Sweden, Thalassinoides exhibit a broad spectrum of geometries in pre-omission, omission and post-omission trace fossil suites. In Cretaceous chalks in Denmark, variations in the branching geometry of Thalassinoides are directly related to incipient hardground development. In Tertiary pelagic limestones in New Zealand, smooth-walled, idiomorphic Thalassinoides burrows grade into stenomorphic Thalassinoides borings with scratch traces on the walls, which were excavated in semi-lithified limestone. In Quaternary mixed carbonate-siliciclastic strata in northern Mexico, geometries of Thalassinoides burrow systems are controlled by the texturally heterogeneous substrate containing sand, gravel and diverse shells. Although different ichnospecies might be assigned to the separate components of each of these examples, it can be demonstrated that they actually belong to one burrow system.


ELDER, William P., Consulting Paleontologist, Lafayette, CA, USA

For decades, geologists have recognized an interval of coquinoid limestone beds composed almost entirely of Buchia sublaevis that spans essentially the entire length of the Arctic slope of Alaska (1000 km). The origin of this interval has been much speculated, but heretofore, no paleontologic study has been published on the beds. In this study, three stratigraphic sections were measured through the coquinoid interval: A 20 m section on Thetis Creek, a 26.4 m section on the Upper Ipewik River, and a 21 m section on the Pitmegea River. The lithologic characteristics of beds down to 1 cm in thickness were noted as well as sedimentologic and taphonomic details of the cyclic Buchia sequences. Geochemical samples from the interval also were analyzed.

The study sections lie within a thick interval of dark, non-fossiliferous Kingak Shale. Their basal parts are characterized by greenish gray or reddish shale without fossils. The middle parts contain 4.0 to 5.3 meters of Buchia-rich beds with 20­23 cycles, each typically displaying a gradual increase in Buchia abundance and size up section. The upper portions of the cycles often form limestone beds composed of Buchia packstone. Above this interval, the sections return to greenish gray or reddish shale without Buchia and contain quartz-rich black sandstones. Observations of the coquinoid beds indicate they may represent in situ biogenic shell concentrations developed during times of reduced clay sedimentation rates and/or increased biogenic productivity. A site of deposition below storm wave base at the outer shelf or upper slope is suggested.


ETNIER, Michael A., Dept. of Anthropology, University of Washington, Seattle, WA, USA

As pinniped populations in the eastern North Pacific continue to increase, competition with humans will undoubtedly increase as well. Management decisions have to distinguish between the re-establishment of old patterns of pinniped behavior and behavioral patterns that have only developed recently. However, detailed accounts of pinniped behavioral patterns in the eastern North Pacific typically post-date the onset of the global commercial fur and oil trade. Consequently, their utility in guiding management decisions is minimal.

Archaeological deposits from coastal sites document the economic importance of pinnipeds in the eastern North Pacific for nearly 10,000 years. The accumulation of pinniped skeletal material in sites throughout western North America provides a vast source of data that can inform on behavioral patterns prior to the onset of commercial sealing. To date, these sources of data have largely been ignored outside of the archaeological literature.

Analysis of the pinniped skeletal remains from the Ozette archaeological site in western Washington documents surprising differences between observed relative abundance and the relative abundance expected based on historically documented migration patterns. Today, California sea lions (Zalophus californianus) are the most abundant pinniped in near-shore environments of the Washington coast. Archaeologically, however, they are essentially absent. In contrast, Guadalupe fur seals (Arctocephalus townsendi) today are thought to be restricted to waters south of central California. Nevertheless, A. townsendiis represented in low frequencies throughout the 500-year stratigraphic sequence at Ozette. These two examples serve to illustrate the point that archaeological data can provide valuable insights into behavioral patterns of pinnipeds prior to the onset of the commercial seal industry and, by extension, can contribute to informed management decisions concerning pinnipeds in the eastern North Pacific.


FARKE, Andrew A., South Dakota School of Mines and Technology, Rapid City, SD, USA

The frontal sinus complex of ceratopsid dinosaurs varies in its size and extent and is largest in chasmosaurines such as Triceratops. The sinus complex is divided into two parts: a large cavity within the frontal bones and cornual sinuses entering the postorbital horns. While the frontal cavities have been well described, the cornual sinuses are not well known due to their relative inaccessibility. Several specimens referable to Triceratops or Torosaurus, including juvenile and adult horn cores and a natural cast of the cornual sinus, elucidate the form of the sinuses in these animals. Juvenile chasmosaurine postorbitals from the Hell Creek Formation of western North America show that the cornual sinuses started as a small dimple on the ventral surface of the postorbital. With growth, the sinus extended and expanded into the postorbital horn. While the ceratopsid cornual sinuses are often considered an analogue to the cornual sinuses of bovid mammals, they are clearly quite different. Bovid cornual sinuses are lined by numerous bony struts, but the cornual sinuses are simple cavities in Triceratops. Postorbital horn size and cornual sinus size seem to be correlated, suggesting that the cornual sinuses may have eliminated structurally unnecessary bone in large horn cores. Further research will shed light on the function and morphology of the ceratopsid sinus complex.