A Memorial for William V. Sliter

William V. (Bill) Sliter, an internationally known micropaleontologist and research geologist for the U.S. Geological Survey, passed away suddenly, October, 1997, while talking to a colleague in his office. In his honor, B. Huber, T. Bralower, and M. Leckie organized a keynote symposium ‘‘Paleoecological and Geochemical Signatures of Cretaceous Anoxic Events’’ at the 1998 annual meeting of the Geological Society of America in Toronto, Canada. This theme issue of the Journal of Foraminiferal Research contains the published papers from the symposium and is dedicated to his memory

A Memorial for William V. Sliter

William V. (Bill) Sliter, an internationally known micropaleontologist and research geologist for the U.S. Geological Survey, passed away suddenly, October, 1997, while talking to a colleague in his office. In his honor, B. Huber, T. Bralower, and M. Leckie organized a keynote symposium ‘‘Paleoecological and Geochemical Signatures of Cretaceous Anoxic Events’’ at the 1998 annual meeting of the Geological Society of America in Toronto, Canada. This theme issue of the Journal of Foraminiferal Research contains the published papers from the symposium and is dedicated to his memory

Origin and Development of Globigerina quinqueloba Natland in the North Pacific

Globigerina quinqueloba Natland is a characteristic planktonic foraminifer inhabiting temperate-subarctic water masses of the world oceans today. Morphotypes referred to Globigerina angustiumbilicata (Bolli) are common to abundant in Miocene deposits at the western and eastern margins of the North Pacific. Both these species are characterized by an average of five chambers in the final whorl and extremely simple morphology. Only subtle differences allow their separation when populations, rather than individuals, are examined. A direct lineage is proposed and illustrated from Globigerina angustiumbilicata to G. quinqueloba within the Middle Miocene to Recent interval. Populations of the Globigerina angustiumbilicata-G. quinqueloba lineage were studied from Middle Miocene ("Globorotalia fohsi barisanensis" Zone) through Pliocene deposits from Honshu Island, California, and the Mohole cores. Recent populations of Globigerina quinqueloba were studied from the eastern and western North Pacific as well as from the Sea of Japan. The following characteristics were measured on an average of 20 individuals from each fossil or Recent population; test diameter, diameter of the proloculus, total number of chambers, number of chambers in the final whorl, coiling direction, and character of the last formed chamber and aperture. Measurements and analysis demonstrate that only three morphologic characters within the lineage exhibit significant variation during the interval studied. These include test diameter, shape of the final chamber and aperture, and spinosity of the test surface. Average test diameter increases from less than 150 microns with in Middle Miocene populations to greater than 200 microns in Pliocene through Recent populations. Specimens with a simple aperture and final chamber are common in Middle Miocene horizons whereas individuals with an aberrant last chamber and lip comprise up to 50 percent of some Recent populations. A qualitative trend is apparent from smooth to hispid tests reflecting a possible change in wall microstructure with time. Oligocene populations have smooth test surfaces, Middle Miocene populations exhibit smooth to finely hispid surfaces, whereas Late Miocene through Recent populations display prominantly hispid surfaces. The study illustrates a long period gradational morphoseries from Globigerina angustiumbilicata to G. quinqueloba. Complications in interpretation of morphologic trends arise due to ecophenotypic variation within populations of a given horizon. The subtle nature of variation among simple morphologic characters during the Middle Miocene through Recent interval hinders a clearcut separation of the two species. Moreover, analysis of population characteristics, rather than analysis of individuals, demonstrates the difficulties inherent in the use of species limits defined on the basis of a single type specimen. Nevertheless, arbitrary statistical limits allow individuals assigned to Globigerina quinqueloba to be initially recognized within the Miocene "Globorotalia mayeri" Zone. Statistically defined populations of Globigerina quinqueloba appear initially within the Miocene "Globorotalia menardii" Zone

7. DISSOLUTION AND PRESERVATION OF DIATOMS IN THE SEA OF JAPAN AND THE EFFECT ON SEDIMENT THANATOCOENOSIS 1

ABSTRACT Sediments of Pliocene age from the Sea of Japan as well as the North Pacific frequently contain abundant remains of the centric diatom, Coscinodiscus marginatus, a species which is neither abundant in surface waters nor in surface sediments of those regions. To test whether these occurrences are a product of opaline silica dissolution, we selected several sediment samples from the Quaternary record of Hole 798A which had opaline silica concentrations ranging from less than 5% to approximately 16%. Laboratory-timed dissolution experiments using an alkaline solution (40 mL of 2 M Na 2 CO 3 ) were carried out at 80° C on the three bulk samples. At the end of each time interval the samples were centrifuged and the supernatant prepared for microscopic examination. The two samples with less than 5% opaline silica contained no diatoms or highly fragmented forms after the first 5 min of the experiment had elapsed. The third sample (with 16% opaline silica), however, showed an increase in percent C. marginatus as dissolution progressed (from less than 5% to more than 35%). These data suggest that high abundances of C. marginatus in sediments may be due to silica dissolution rather than to any unique paleoceanographic signal

An Unprecedented Role Reversal: Ground Beetle Larvae (Coleoptera: Carabidae) Lure Amphibians and Prey upon Them

Amphibians often feed on beetle larvae, including those of ground beetles (Carabidae). Preliminary reports have detailed an unusual trophic interaction in which, in contrast, larvae of the ground beetle Epomis prey upon juvenile and adult amphibians. While it is known that these larvae feed exclusively on amphibians, how the predator-prey encounter occurs to the advantage of the beetle larvae had been unknown to date. Using laboratory observations and controlled experiments, we recorded the feeding behavior of Epomis larvae, as well as the behavior of their amphibian prey. Here we reveal that larvae of two species of Epomis (E. circumscriptus and E. dejeani) lure their potential predator, taking advantage of the amphibian's predation behavior. The Epomis larva combines a sit-and-wait strategy with unique movements of its antennae and mandibles to draw the attention of the amphibian to the presence of a potential prey. The intensity of this enticement increases with decreasing distance between the larva and the amphibian. When the amphibian attacks, the larva almost always manages to avoid the predator's protracted tongue, exploiting the opportunity to attach itself to the amphibian's body and initiate feeding. Our findings suggest that the trophic interaction between Epomis larvae and amphibians is one of the only natural cases of obligatory predator-prey role reversal. Moreover, this interaction involves a small insect larva that successfully lures and preys on a larger vertebrate. Such role reversal is exceptional in the animal world, extending our perspective of co-evolution in the arms race between predator and prey, and suggesting that counterattack defense behavior has evolved into predator-prey role reversal