Invertebrate Fossils Research Articles

The trophic structure of the biota of the Peterborough Member, Oxford Clay Formation (Jurassic), UK

The Peterborough Member of the Oxford Clay Formation is organic-rich and contains an abundance of well-preserved vertebrate and invertebrate fossils. A high nutrient input supported a diverse biota. Phytoplankton was exceptionally abundant in the surface water, and formed the basis for an intricate food web in both surface and bottom waters. Top predators include some of the largest known Mesozoic marine reptiles. A giant teleost fish was analogous to modern filter feeding whales and sharks. Benthic faunas depended on organic matter sinking from surface waters, and two parallel food webs may have existed. Trophic partitioning allowed the higher level predators to become diverse, especially the plesiosaurs. Productivity was high in the surface waters, probably high in the mid-water column, and high on the sea floor at times, although benthic diversity may have been reduced due to substrate consistency and/or dysoxia. Bacterial activity within the sediment was also intense. The contribution of organic material to the sea floor was high, but heterotrophic reworking probably reduced the abundance considerably during early diagenesis. A decrease in organic carbon content in the Upper Callovian and Lower Oxfordian parts of the Oxford Clay Formation parallels a decreasing abundance of vertebrate fossils.

An enigmatic cap-shaped fossil from the Middle Cambrian of North Greenland

Nyeboeconus robisoni gen. et sp. nov., is described from the Middle Cambrian Henson Gletscher Formation of western North Greenland. Some authors have interpreted similar shelIs as chondrophorine hydrozoans or invertebrate fossils of uncertain systematic position. The coiled, cap-shaped shell and the presence of an internal plate, or pegma, suggest, however, that this new form is the second genus to be described of the Family Enigmaconidae MacKinnon, 1985 (Mollusca, Class Helcionelloida), otherwise known only from rocks of similar age in New Zealand.

Sensitivity of tropical-African aquatic invertebrates to short-term trends in lake level and salinity: a paleolimnological test at Lake Oloidien, Kenya

Aquatic invertebrates are intrinsically capable of rapid and sensitive response to changes in their lacustrine habitat. Fossil invertebrate assemblages preserved in the sediments of a climate-sensitive lake can thus produce high-resolution proxy records of past climate. In shallow lakes, however, a potential conflict exists between the sensitivity of biota to frequent habitat change in their fluctuating environment and the increased probability of disturbance of selected proxy records by bioturbation and physical mixing of sediments. I investigated this problem with tropical-African aquatic invertebrate faunas in a paleolimnological sensitivity study that incorporates both the response of biota to short-term habitat change and the taphonomic integrity of fossil assemblages in a small, shallow, and hydrologically closed lacustrine basin. Analysis of chironomid, cladoceran, and ostracode remains in a210Pb-dated short core from Lake Oloidien (Kenya) indicates that habitat changes accompanying the late 19th- and 20th-century fluctuations in lake level (Zmax range: 3 to 18 m) and salinity (conductivity range:c. 400 toc. 2000–4000 µS cm−1) were sufficient to drastically alter the composition of local benthic and planktonic invertebrate faunas. This response remained relatively unaffected by taphonomic phenomena during its incorporation into the sediment record. Results indicate that tropical-African aquatic invertebrate faunas in suitable climate-sensitive lakes are a valuable tool to resolve paleoclimatic fluctuations on a timescale of decades.

An annual fossil record of production, planktivory and piscivory during whole-lake manipulations

Annual and subannual paleolimnological records of pigments and zooplankton were used to analyze three whole-lake manipulations. The relative abundance of cladoceran remains in recent seasonal laminae was significantly correlated with the relative abundance of species in the plankton (r 2=0.59,P<0.001). Comparison of food-web structure after piscivore introduction showed that there are multiple outcomes of predation and that final food-web structure depended on the strength of interaction between piscivorous and planktivorous fish. Intense predation on cyprinids (Phoxinus eos, P. neogaeus, Umbra limi) by largemouth bass (Micropterus salmoides) allowed large herbivores (Daphnia pulex) and invertebrate predators (Chaoborus punctipennis) to dominate. Analysis of fossil invertebrate morphology suggested that small grazers (Bosmina longirostris, Diaphanosoma birgei) were eliminated by invertebrate predators. Under moderate predation by rainbow trout (Oncorhynchus mykiss), cyprinids remained, only intermediate-size herbivores (D. rosea) increased in abundance, andBosmina persisted. In contrast to food-web manipulations, increased algal abundance resulting from watershed disturbance (road construction) did not alter the species composition or size-structure of fossil Cladocera.

Transfers of algal, microfossil, plant, and vertebrate materials to the University of California Museum of Paleontology

The university of California Museum of Paleontology (UCMP), located on the Berkeley Campus, is a major repository of fossils and paleontological materials. The collection, one of the largest in the nation, originated in 1873 and has been added to continuously since then. In 1921, the Museum of Paleontology was officially initiated with an endowment though the generosity of Annie Alexander of Oakland, California (Grinnell, 1958). The UCMP collections are divided into four specimen collection management units and one collection of paleontological materials, such as rock, sediment, and amber samples, and various teaching collections. The specimen collection units are Fossil Prokaryotes and Protists, Fossil and Recent Invertebrates, Paleobotany and Palynology, and Vertebrate Paleontology. Each of these units has its own manager and each consists of hundreds of thousands of specimens or more and thousands of primary and secondary type specimens. The Museum is supported by the Annie Alexander Endowment and the University of California, Berkeley. It has a staff of 11, and a group of faculty curators, affiliate faculty curators from other University of California campuses, research associates, and associated graduate and undergraduate students. It is a general purpose research museum open to the scientific community and, although it does no formal instruction, it provides instructional exhibits and teaching collections at Berkeley and other campuses. It publishes Paleobios (ISSN 0031-0298), an occasional publication containing a variety of paleontological, peer-reviewed papers. UCMP is also involved in public and school activities at the Museum in Berkeley and at the University of California, Berkeley, Museum of Science, Art and Culture, at Blackhawk Plaza, Danville, California.

Collection transfer

I he National Museum of Natural History (Smithsonian Institution), Department 01 Paleobiology, recently received the collection of invertebrate fossils (except Insecta and Patagonia material) formerly housed in the Princeton University, Department of Geological and Geophysical Sciences. This fine collection contains approximately 70,000 specimens; type and nontype specimens were stored together in taxonomic order. Current documentation for the entire collection consists of a card catalogue. Following curation, the specimens will be housed taxonomically in standing type and nontype collections. Lists of type specimens received will be published as they are isolated. Borrowers should return specimens to the Department of Paleobiology, National Museum of Natural History, upon completion of loans.

Putative Paleocene plesiosaurs from Cajon Pass, California, U.S.A.

Two elasmosaurid plesiosaur specimens have been recovered from rocks of the San Francisquito Formation(?) in Cajon Pass, California. Some invertebrate fossils and palynomorphs from the San Francisquito Formation(?) here indicate a Paleocene age, but no direct association of Paleocene fossils and the plesiosaur fossils can be demonstrated. Therefore, the Cajon Pass plesiosaurs are most reasonably considered Late Cretaceous.

Biomonitoring past salinity changes in an athalassic subarctic lake

A short sediment core was taken from a small saline lake located on an intermontane plateau in the central Yukon Territory, Canada. In July 1990, chemical analyses indicated that, although the lake was shallow (Zmax=1.1 m), it was also chemically stratified, with hyposaline (9.9 to 10.0 g L−1) surface waters and slightly mesosaline (22.0 g L−1) deeper waters. The surface water was dominated by Na+ and HCO 3 − . To our knowledge, this is the northernmost athalassic saline lake yet recorded. Quantification of algal (diatom, chrysophyte, and pigment) and invertebrate (chironomid, ceratopogonid, andChaoborus) fossils at four stratigraphic levels indicated that the lake sediments preserved numerous biological indicators that could be used to infer recent lake development. Many of the taxa are found in other athalassic salt lakes. The most striking stratigraphic change was a remarkable drop in the species richness of diatoms and invertebrates in the recent sediments, which parallels the elimination of species characteristic of less saline conditions. Halophilous taxa dominate the most recent sediments, indicating the development of more saline conditions. At the same time, a significant shift in chrysophyte cyst composition was observed. Fossil carotenoids and chlorophylls indicated a decrease in total algal abundance in recent sediments, as green and blue-green algae replaced diatoms and chrysophytes. Together, these paleolimnological data suggest a recent shift to drier conditions or increased evaporation in the central Yukon Territory.

The accumulation and disposal of Gideon Mantell's fossil collections and their role in the history of British palaeontology

Through his early interest in fossils, Mantell participated in the geological exploration of the Weald and the Chalk Downs around Lewes. The material he accumulated contributed to the descriptive phase of British palaeontology and formed his notable museums at Lewes and Brighton, before its eventual acquisition by the British Museum. The nature of his collections, their significance and use in the interpretation of both vertebrate and invertebrate fossils and our knowledge of Cretaceous faunas, are discussed.

Gideon Mantell and the ‘Xanthidia’

Gideon Mantell's renown stems from his studies of the dinosaurs and large invertebrate fossils of southeastern England. However, his researches were not limited to macroscopic fossils of moderate to large size, but also comprised studies under the microscope of some of the very smallest fossils. On these also, he made fundamental contributions to scientific knowledge, though inadvertently leaving later workers a legacy of taxonomic problems. His work is summarized, and the story of its rediscovery told, by a person privileged not only to bring Mantell's researches to the attention of modern micropalaeontologists, but also to participate in the fluke rediscovery of one of Mantell's lost type specimens.

Distribution of Late Silurian (?) and Early Devonian grey-green sandstones in the Liefdefjorden-Bockfjorden area, Spitsbergen

Lithologic, petrographic and paleontologic data for the various areas of late Silurian (?) and early Devonian grey-green sandstones (greywackes) in the Liefdefjord area of northern Spitsbergen are evaluated. A number of new localities with fossil fauna have been detected in these sandstones, both to the north and south of Liefdcfjordcn. It is shown that vertebrate and invertebrate fossils occur at lower levels than hitherto believed. Differences in the amounts of plagioclase and potash feldspar in the sandstones north and south of the fjord, as well as the finds of fossils, suggest that the Siktefjellet Sandstone is restricted to the type area north of Liefdefjorden. The grey-green sandstones south of Liefdefjorden are correlated with the Andreebrecn Sandstone Formation of the Red Bay Group.

Structure of alpha 2-macroglobulin from the arthropod Limulus polyphemus

A structural and functional homologue of vertebrate alpha 2-macroglobulin (alpha 2M) has been identified in the hemolymph and blood cells of the arthropod Limulus polyphemus, one of the oldest living fossil invertebrates (Quigley, J. P., and Armstrong, P. B. (1985) J. Biol. Chem. 260, 12715-12719). The subunit molecular mass is 185 kDa. The native molecular mass, determined by scanning transmission electron microscopy (STEM) under conditions in which the linear relationship between the STEM large angle detector signal and specimen mass thickness allows the determination of the total macromolecular mass, was 354 +/- 35 kDa. Sedimentation equilibrium measurements gave a value of 366 kDa, independent of solute concentration. Sedimentation velocity experiments indicated a homogeneous component with a frictional ratio of 1.41. Thus, the native structure appears to be a dimer, with a somewhat extended conformation. The behavior during gel permeation chromatography was anomalous, yielding an apparent molecular mass approximately half-way between that expected for the dimeric and tetrameric configurations. Transmission electron microscopy of negatively stained preparations revealed a dimeric butterfly-like structure that collapsed following reaction with chymotrypsin.

Distribution of Late Silurian (?) and Early Devonian grey-green sandstones in the Liefdefjorden-Bockfjorden area, Spitsbergen

Lithologic, petrographic and paleontologic data for the various areas of late Silurian (?) and early Devonian grey-green sandstones (greywackes) in the Liefdefjord area of northern Spitsbergen are evaluated. A number of new localities with fossil fauna have been detected in these sandstones, both to the north and south of Liefdcfjordcn. It is shown that vertebrate and invertebrate fossils occur at lower levels than hitherto believed. Differences in the amounts of plagioclase and potash feldspar in the sandstones north and south of the fjord, as well as the finds of fossils, suggest that the Siktefjellet Sandstone is restricted to the type area north of Liefdefjorden. The grey-green sandstones south of Liefdefjorden are correlated with the Andreebrecn Sandstone Formation of the Red Bay Group.

Washington-Oregon Tertiary: Evidence for Influence of Eustatic Controls on Coastal Sedimentation

Tertiary sediments deposited along coastal Washington-Oregon extend from onshore to the base of the continental slope and beyond (Nitinat and Astoria deep sea fans). At least five Tertiary depocenters have been identified on the outer continental shelf, where maximum sedimentary section thicknesses of over 8,000 m (26,000 ft) are indicated. Stratigraphic sequences are strongly cyclical and evidence indicates that they are grounded by long-term regional hiatuses. Although previous interpretations attribute these stratigraphic sequences to four depositional/orogenic cycles, there is evidence that eustatic sea level changes may have had a major influence on Tertiary sedimentation along the Pacific Northwest Coast. Stratigraphic sequences are mostly marine, and contain larger fossil invertebrates, foraminifers, calcareous nannofossils, and siliceous microplankton, which can be dated and correlated both to California provincial stages and to worldwide chronostratigraphic standards. Stratigraphic correlation charts plotted on an absolute time scale display remarkable concordance with the supercycles and eustatic curve of the Haq-Vail Cenozoic global cycle chart. Along coastal Washington-Oregon Eocene to early Oligocene, early through middle Miocene, and Pliocene-Pleistocene sea level maximae are represented by extensive marine deposits; although both the late Oligocene (Chattian-late Zemorrian) and the late Miocene (Tortonian-late Mohnian) regressions are marked by major regional unconformities. Recognition thatmore » depositional sequences in this region were at least in part eustatically controlled is important because it could greatly simplify future subsurface geologic interpretations.« less

Fossil invertebrate collections moved from National Museum

Paleontological investigations have played a critical role in the research of the U.S. Geological Survey (USGS) since its founding in 1879. From about 1950 until recently, the bulk of these fossil materials collected by USGS field geologists was housed in the U.S. National Museum of Natural History (Smithsonian Institution) in Washington, D.C, under the control of the Branch of Paleontology and Stratigraphy of the USGS. Large biostratigraphic sets of USGS collections also resided in Denver, Colorado, and Menlo Park, California, at the USGS regional centers.

Cambrian and Devonian invertebrate collections at the Milwaukee Public Museum

The Milwaukee Public Museum has recently completed the computerized curation of its Cambrian and Devonian invertebrate fossil collections. This notice is intended to alert the paleontological community of the availability of these collections for study. The curation was supported by the Biological Research Resources Program of the National Science Foundation. The Cambrian and Devonian collections have approximately 87,000 specimens from 1,977 localities. Isolated specimens were counted directly, but counts of multiple specimens on slabs are conservative. Thus, the number of specimens represents a minimum number of fossils and more careful counting of material on slabs will increase the total.

Fossil Invertebrate Evidence For Late Wisconsin Environments At The Lamb Spring Site, Colorado

Interdisciplinary studies of Quaternary fossil groups strengthen the paleoenvironmental interpretations of archaeological sites. In this paper, we present the results of an investigation of an asse...

The Fossil Record, Function, and Possible Origins of Shell Color Patterns in Paleozoic Marine Invertebrates

Fossil invertebrate shells and carapaces displaying preserved original color patterns are among the rarest fossils. The fossil record of color patterns extends into the Middle Cambrian where the trilobite Anomocare displays a fan-like array of stripes on the pygidium. About 180 Paleozic genera are known with patterns, including trilobites, cephalopods, gastropods, brachiopods, bivalves, crinoids, and crustaceans. Based upon an analysis of these taxa, it appears that patterns and pigments in middle and late Paleozoic invertebrates may have served several functions such as warning displays, light screening, camouflage, or waste disposal. However, the presence of color patterns in fossil invertebrates in the early Paleozoic may have developed prior to the evolution of vision sufficiently sophisticated to see them. This suggests that camouflage and warning displays were not the original functions of color patterns, and that in the earliest Paleozoic they may not have been functional. The authors propose a hypothesis that involves three developmental phases in the evolution of invertebrate color patterns: (1) the incorporation of metabolic by-products, perhaps some pigmented and some not pigmented, into shells and carapaces as a means of disposal of dietary or metabolic wastes, (2) use of these pigments and patterns as an environmental adaptation, suchmore » as light screening, and (3) display during and following the evolution of vision in predators sufficiently sophisticated to see the patterns.« less

How good was the fossil record? Clues from the Californian Pleistocene

The living members of 113 families of bivalves and gastropods of the Californian Province include 698 species living at shelf depths, of which 538 or 77% are known as Pleistocene fossils from the same region; another 113 fossil species are extralimital, and 98 are extinct. Living species not found as fossils are chiefly rare today, and/or minute, fragile, and/or from deeper shelf habitats. Sampling of the Pleistocene record has been biased towards shallow-water assemblages. Fragile and minute forms are probably underrepresented in the record. Rare forms, however, are still appearing as new studies are conducted, and many rare species are yet to be discovered. At least 85% of durably skeletonized living species may have been captured in the record. It is probable that most durably skeletonized invertebrate species were represented in lithostratigraphic units throughout the Phanerozoic, but that this record is lost owing to erosion, burial, and destruction of skeletons in situ. The bulk of the marine invertebrate fossil record does not represent a series of unusual skeletal accumulations, but rather the preserved remnants of an excellent original record formed through ordinary though episodic processes.

Heterochrony as an alternative to species selectionin the generation of phyletic trends

Phyletic trends can be accounted for by anagenesis or cladogenesis in conjunction with species selection or effect maroevolution. Data from the fossil record support anagenesis, involving single ancestor-descendent relationships, rather than cladogenesis as the normal or dominant pattern. Examples are given from fossil invertebrates of paedomorphosis and peramorphosis, of which the former appears to predominate.