Palaeontologische Zeitschrift 

About: Palaeontologische Zeitschrift is an academic journal published by E. Schweizerbart. The journal publishes majorly in the area(s): Devonian & Genus. It has an ISSN identifier of 0031-0220. Over the lifetime, 2208 publications have been published receiving 27671 citations. The journal is also known as: Journal of Paläontologische Gesellschaft & Paläontologische Zeitschrift (Print).

Neue Mikrofossilien des baltischen Silurs. IV

Abstract: Die vorliegende Fortsetzung der begonnenen Untersuchung uber Mikrofossilien silurischer Sedimente des Baltikums berichtet uber die dabei beobachteten agglutinierenden Foraminiferen, unter denen diejenigen mit vollig erhaltener organischer Grundlage der Schale besonders bemerkenswert erscheinen. Ferner sind die Untersuchungen uber die „Chitinozoen” weitergefuhrt und machen deren Natur als Protozoen wahrscheinlicher. Im ubrigen wird noch uber einige recht problematische Mikrofossilien, die „schwarzen Stabchen” und einen in einem Feuerstein aufgefundenen Organismus, berichtet. Im bohmischen Silur konnte ich kurzlich ebenfalls das Vorkommen der Chitinozoen nachweisen, und zwarConochitina cf.claviformis undC. cf.ancyrea im Silur von Sodenitz (Ee2),Desmochitina cf.erratica im Silur von Dlauha hora (E2). Auch hier scheinen sie haufig zu sein.

Modern planktic foraminifera

Abstract: Planktic foraminifers are marine protozoans with calcareous Shells and chambered tests. They first appeared in the mid-Jurassic and spread since the mid-Cretaceous over all the world’s oceans. Modern planktic foraminifers evolved since the early Tertiary, when the first spinose species occurred. Most species live in the surface to sub-thermocline layer of the open ocean, and in marginal seas like the Mediterranean, Caribbean, South China Sea, and Red Sea. Planktic foraminifers are absent in shallow marginal seas, for example, the North Sea. Planktic foraminifers respond to food, temperature and chemistry of the ambient seawater. Species abundance varies according to seasons, water masses, and water depths. Symbiont-bearing species depend on light and are restricted to the euphotic zone. Planktic foraminifers constitute a minor portion of total Zooplankton, but are major producers of marine calcareous particles (shells) deposited on the ocean floor where they form the so-called foraminiferal ooze. Planktic foraminifers contribute substantially to the fossil record of marine Sediments and are of high ecologic, paleoceanographic, and stratigraphic significance since the mid-Cretaceous. Radiocarbon (14C) gives an absolute age of shell formation within late Pleistocene and Holocene Sediments. Factors that determine the modern faunal composition are applied to Interpretation of the fossil assemblages, for example, by multiple regression techniques (transfer functions) to yield an estimate on ancient environmental parameters. The chemical composition of the calcareous shell (stable isotopes and trace elements) holds clues to the chemical and physical State of the ambient seawater and is useful in the reconstruction of temperature, chemical State, and biological productivity of the ancient marine environment.

Ichthyosauria: their diversity, distribution, and phylogeny

Abstract: The Ichthyosauria is the group of Mesozoic marine reptiles that was most highly adapted to the aquatic environment. The first ichthyosaurs from the upper Lower Triassic (Spathian) already show a suite of unique characters (very large eyes, elongate snout, deeply amphicoelous vertebrae, limb modified to fins) correlated with a fully aquatic existence and probably were unable to leave the water. The key evolutionary innovation was vivipary, giving birth to live young, which is documented by the fossil record since the end of the Anisian. Major evolutionary trends in the locomotor apparatus are the increasing modification of the fin skeleton to a mosaic of bones and the change from anguiliform swimming in the earliest forms to thunniform swimming in the Jurassic and later forms, as evidenced by the shortening of the body and the evolution of a semilunate tail fin. Almost from the beginning, ichthyosaurs had a cosmopolitan distribution which was retained until their extinction in the Cenomanian. Ichthyosaurian diversity is greatest in the Middle Triassic with piscivorous, heterodont, and durophagous forms. Jurassic diversity is greatest in the Liassic, declining to one genus (Platypterygius) in the Cretaceous. Although skull characters indicate that ichthyosaurs were diapsids, their exact position within Diapsida is unclear. A cladistic analysis of the well known genera clarifies relationships within the Ichthyosauria. Most basal areGrippia andUtatsusaurus, followed by the Mixosauridae (Mixosaurus andPhalarodon). The Shastasauridae (Cymbospondylus, Shonisaurus, Besanosaurus) are the most advanced Triassic forms and represent the sistergroup of all post-Triassic ichthyosaurs. These are clearly monophyletic and are termed here the Neoichthyosauria.