Invertebrate Fossils Research Articles

A Late Triassic flora and associated invertebrate fossils from the basal beds of the Chinle Formation in Dinnebito Wash, east-central Arizona, USA

A Late Triassic flora and associated invertebrate fossils from the basal beds of the Chinle Formation in Dinnebito Wash, east-central Arizona, USA

Gastropods Associated with Fossil Traces from Yacoraite Formation (Maastrichtian‐Danian), and its Paleoenvironmental Significance, Jujuy, Northwestern Argentina

Abstract:We present results tending to characterize the new records of invertebrates from the Yacoraite Formation (Maastrichtian‐Danian). The fossils reported come from two stratigraphic sections exposed in the surroundings of Maimará and Jueya, province of Jujuy, northwestern Argentina. The selection was based on geological and paleontological evidence. The recovered fossils include gastropods and invertebrate fossil traces, including Planolites, Skolithos and Gastrochanoelites ichnogenus. As result of our review, we discussed the possibility of assigning the analyzed gastropods to the family Zygopleuridae (gene. et. sp. indet.), as an approximation to the taxonomic resolution of this fossil fauna. The trace fossils were assigned to the archetypical Glossifungites ichnofacies. The study of the fossil assemblage allowed us to define a shallow depositional environment, characteristic of a marine context with high‐energy conditions.

Stable isotopes in chitinous fossils of aquatic invertebrates

Current stable isotope techniques permit the development of new approaches for reconstructing past climate and aquatic food webs based on chitinous invertebrate fossils from lake sediments.

Global patterns of speciation and diversity

In recent years, strikingly consistent patterns of biodiversity have been identified over space, time, organism type and geographical region. A neutral theory (assuming no environmental selection or organismal interactions) has been shown to predict many patterns of ecological biodiversity. This theory is based on a mechanism by which new species arise similarly to point mutations in a population without sexual reproduction. Here we report the simulation of populations with sexual reproduction, mutation and dispersal. We found simulated time dependence of speciation rates, species-area relationships and species abundance distributions consistent with the behaviours found in nature. From our results, we predict steady speciation rates, more species in one-dimensional environments than two-dimensional environments, three scaling regimes of species-area relationships and lognormal distributions of species abundance with an excess of rare species and a tail that may be approximated by Fisher's logarithmic series. These are consistent with dependences reported for, among others, global birds and flowering plants, marine invertebrate fossils, ray-finned fishes, British birds and moths, North American songbirds, mammal fossils from Kansas and Panamanian shrubs. Quantitative comparisons of specific cases are remarkably successful. Our biodiversity results provide additional evidence that species diversity arises without specific physical barriers. This is similar to heavy traffic flows, where traffic jams can form even without accidents or barriers.

Evidence for extinction selectivity throughout the marine invertebrate fossil record

The fossil record has been used to show that in some geologic intervals certain traits of taxa may increase their survivability, and therefore that the risk of extinction is not randomly distributed among taxa. It has also been suggested that traits that buffer against extinction in background times do not confer the same resistance during mass extinction events. An open question is whether at any time in geologic history extinction probabilities were randomly distributed among taxa. Here we use a method for detecting random extinction to demonstrate that during both background and mass extinction times, extinction of marine invertebrate genera has been nonrandom with respect to species richness categories of genera. A possible cause for this nonrandom extinction is selective clustering of extinctions in genera consisting of species which possess extinction-biasing traits. Other potential causes considered here include geographic selectivity, increased extinction susceptibility for species in species-rich genera, or biases related to taxonomic practice and/or sampling heterogeneity. An important theoretical result is that extinction selectivity at the species level cannot be smoothly extrapolated upward to genera; the appearance of random genus extinction with respect to species richness of genera results when extinction has been highly selective at the species level.

The double mass extinction revisited: reassessing the severity, selectivity, and causes of the end-Guadalupian biotic crisis (Late Permian)

The end-Guadalupian extinction, at the end of the Middle Permian, is thought to have been one of the largest biotic crises in the Phanerozoic. Previous estimates suggest that the crisis eliminated 58% of marine invertebrate genera during the Capitanian stage and that its selectivity helped the Modern evolutionary fauna become more diverse than the Paleozoic fauna before the end-Permian mass extinction. However, a new sampling-standardized analysis of Permian diversity trends, based on 53731 marine invertebrate fossil occurrences from 9790 collections, indicates that the end-Guadalupian “extinction” was actually a prolonged but gradual decrease in diversity from the Wordian to the end of the Permian. There was no peak in extinction rates; reduced genus richness exhibited by all studied invertebrate groups and ecological guilds, and in different latitudinal belts, was instead driven by a sharp decrease in origination rates during the Capitanian and Wuchiapingian. The global diversity decrease was exacerbated by changes in beta diversity, most notably a reduction in provinciality due to the loss of marine habitat area and a pronounced decrease in geographic disparity over small distances. Disparity over moderate to large distances was unchanged, suggesting that small-scale beta diversity changes may have resulted from compression of bathymetric ranges and homogenization of onshore-offshore faunal gradients stemming from the spread of deep-water anoxia around the Guadalupian/Lopingian boundary. Although tropical invertebrate genera were no more likely than extratropical ones to become extinct, the marked reduction in origination rates during the Capitanian and Wuchiapingian is consistent with the effects of global cooling (the Kamura Event), but may also be consistent with other environmental stresses such as anoxia. However, a gradual reduction in diversity, rather than a sharp end-Guadalupian extinction, precludes the need to invoke drastic extinction mechanisms and indicates that taxonomic loss at the end of the Paleozoic was concentrated in the traditional end-Permian (end-Changhsingian) extinction, which eliminated 78% of all marine invertebrate genera.

Gryphaea beds (upper Scunthorpe Mudstone Formation; Lower Jurassic) at Scunthorpe, North Lincolnshire, north-east England

Summary The upper part of the Scunthorpe Mudstone Formation (Sinemurian, Lower Jurassic) beneath the Frodingham Ironstone at Scunthorpe, north-east England, comprises richly fossiliferous mudrocks and limestones. These strata were recently exposed in temporary sections north of Scunthorpe and yielded large numbers of gryphaeid oysters and other invertebrate fossils. Many of the oysters are extensively bioeroded and disarticulated, and locally constitute coarse-grained bioclastic limestones. These features indicate establishment of a periodically agitated, shallow-water, photic setting, presaging deposition of the ooidal Frodingham Ironstone during the culmination of mid-Sinemurian shallowing.

Extraordinarily thick-boned fish linked to the aridification of the Qaidam Basin (northern Tibetan Plateau)

Scattered with numerous salt lakes and approximately 2,700-3,200 m above sea level, the giant Qaidam inland basin on the northern Tibetan Plateau has experienced continuing aridification since the beginning of the Late Cenozoic as a result of the India-Asia plate collision and associated uplift of the Tibetan Plateau. Previous evidence of aridification comes mainly from evaporite deposits and salinity-tolerant invertebrate fossils. Vertebrate fossils were rare until recent discoveries of abundant fish. Here, we report an unusual cyprinid fish, Hsianwenia wui, gen. et sp. nov., from Pliocene lake deposits of the Qaidam Basin, characterized by an extraordinarily thick skeleton that occupied almost the entire body. Such enormous skeletal thickening, apparently leaving little room for muscles, is unknown among extant fish. However, an almost identical condition occurs in the much smaller cyprinodontid Aphanius crassicaudus (Cyprinodonyiformes), collected from evaporites exposed along the northern margins of the Mediterranean Sea during the Messinian desiccation period. H. wui and A. crassicaudus both occur in similar deposits rich in carbonates (CaCO(3)) and sulfates (CaSO(4)), indicating that both were adapted to the extreme conditions resulting from the aridification in the two areas. The overall skeletal thickening was most likely formed through deposition of the oversaturated calcium and was apparently a normal feature of the biology and growth of these fish.

Preservation of the shell matrix protein dermatopontin in 1500 year old land snail fossils from the Bonin islands

Organic molecules such as proteins can be preserved in certain fossils. The bulk properties of fossil proteins of both vertebrates and invertebrates have been studied for over half a century. Named proteins have so far been identified, however, only in vertebrate fossils, such as collagen from mammoth bones. Using immunological assays, we examined 1500 year old fossils of the extinct land snail Mandarina luhuana from the Bonin islands for the presence of dermatopontin, a molluscan shell matrix protein. First, we examined the shell microstructure and mineralogy of the fossil shells using scanning electron microscopy (SEM) and powder X-ray diffraction (XRD) in order to estimate the extent of diagenetic alteration. The results suggest that the original microstructure and mineralogy of the shells are preserved. Antiserum raised against the Type-1 dermatopontin fragment of the living land snail Euhadra brandtii showed significant immunological reactivity with the extracts from the fossil shells of M. luhuana. Immunological binding curves drawn for the shell extracts of extant M. aureola and the extinct M. luhuana confirmed the presence of dermatopontin in the fossil shells and provided an estimate that about 75–98% of the original dermatopontin was lost from the M. luhuana fossils. This is the first report of a named protein being identified in invertebrate fossils.

EXCEPTIONAL PRESERVATION OF PLANTS AND INVERTEBRATES BY PHOSPHATIZATION, RIVERSLEIGH, AUSTRALIA

Phosphatic concretions containing mineralized three-dimensional plant and invertebrate tissues occur in a mid-Cenozoic terrestrial freshwater carbonate deposit at the Riversleigh World Heritage area in northwestern Queensland, Australia. Mineralogical composition and microstructure of the concretions show that this fossil assemblage was preserved by rapid, early diagenetic phosphatization. Preserved material includes tissues typically considered to have a poor potential for phosphatization, such as internal plant structure and arthropod exoskeletal components. Phosphatization may have been mediated by the presence of microbial films. Study of this rich assemblage has the potential to make significant contributions to both the Australian Cenozoic terrestrial invertebrate fossil record and the Cenozoic plant megafossil record of northern Australia.

Measuring vertical tectonic motion at the intersection of the Santa Cruz-Catalina Ridge and Northern Channel Islands platform, California Continental Borderland, using submerged paleoshorelines

Research Article| July 01, 2008 Measuring vertical tectonic motion at the intersection of the Santa Cruz–Catalina Ridge and Northern Channel Islands platform, California Continental Borderland, using submerged paleoshorelines Jason D. Chaytor; Jason D. Chaytor † 1College of Oceanic and Atmospheric Sciences, Oregon State University, 104 Ocean Administration Building, Corvallis, Oregon 97331, USA §Present address: Department of Geology and Geophysics, Woods Hole Oceanographic Institution, MS 24, Woods Hole, Massachusetts 02543, USA. †E-mail: jchaytor@whoi.edu Search for other works by this author on: GSW Google Scholar Chris Goldfinger; Chris Goldfinger 1College of Oceanic and Atmospheric Sciences, Oregon State University, 104 Ocean Administration Building, Corvallis, Oregon 97331, USA Search for other works by this author on: GSW Google Scholar Melissa A. Meiner; Melissa A. Meiner 1College of Oceanic and Atmospheric Sciences, Oregon State University, 104 Ocean Administration Building, Corvallis, Oregon 97331, USA #Present address: Department of Geology, University of Hawaii at Hilo, 200 W. Kawili Street, Hilo, Hawaii 96720, USA. Search for other works by this author on: GSW Google Scholar Gary J. Huftile; Gary J. Huftile 2School of Natural Resource Sciences, Queensland University of Technology, 2 George Street, Brisbane, QLD 4001, Australia Search for other works by this author on: GSW Google Scholar Christopher G. Romsos; Christopher G. Romsos 3College of Oceanic and Atmospheric Sciences, Oregon State University, 104 Ocean Administration Building, Corvallis, Oregon 97331, USA Search for other works by this author on: GSW Google Scholar Mark R. Legg Mark R. Legg 4Legg Geophysical, Huntington Beach, California 92647, USA Search for other works by this author on: GSW Google Scholar GSA Bulletin (2008) 120 (7-8): 1053–1071. https://doi.org/10.1130/B26316.1 Article history received: 20 Aug 2007 rev-recd: 06 Feb 2008 accepted: 15 Feb 2008 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Jason D. Chaytor, Chris Goldfinger, Melissa A. Meiner, Gary J. Huftile, Christopher G. Romsos, Mark R. Legg; Measuring vertical tectonic motion at the intersection of the Santa Cruz–Catalina Ridge and Northern Channel Islands platform, California Continental Borderland, using submerged paleoshorelines. GSA Bulletin 2008;; 120 (7-8): 1053–1071. doi: https://doi.org/10.1130/B26316.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract We used submerged paleoshorelines as strain markers to investigate Holocene and late Pleistocene vertical tectonic movement at the intersection of the offshore Santa Cruz–Catalina Ridge with the southern boundary of the Western Transverse Ranges, within the California Continental Borderland. Past submerged shoreline positions were identified using high-resolution multibeam bathymetry, side-scan sonar, submersible observations, and the presence of intertidal and subtidal invertebrate fossils. Numerous accelerator mass spectrometry (AMS) 14C ages of shells from these paleoshorelines were found to be between ~27,000 yr radiocarbon (RC) and 11,500 yr before present, indicative of shoreline colonization during and following the Last Glacial Maximum (LGM), establishing these paleoshorelines as a usable datum for measuring vertical change since this time. Removal of the nontectonic component of vertical change using an ice-volume-equivalent eustatic sea-level compilation indicates between 20 and 45 m of uplift of the eastern part of the Northern Channel Islands block since the LGM lowstand, resulting in an uplift rate of 1.50 ± 0.59 mm/yr over the last 23 k.y. This rate closely matches uplift predicted by published slip rates for the Channel Islands thrust, which underlies the Northern Channel Islands platform. Results from post-LGM shoreline features on Pilgrim Banks are somewhat more ambiguous. Submarine paleoshoreline uplift, together with the extensive upper-crustal fold-thrust style of deformation, illustrates the transpressional interaction of the Borderland and the Western Transverse Ranges blocks where the Santa Cruz–Catalina Ridge and northern Channel Islands intersect. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Using GIS to study palaeobiogeographic and macroevolutionary patterns in soft-bodied Cambrian arthropods

Soft-bodied Cambrian arthropods from Burgess Shale-type deposits are some of the most famous and extensively studied fossil invertebrates, but global species-level assessments of their biogeographic patterns have not previously been explored quantitatively. Here we use a newly developed occurrence database, in conjunction with Geographic Information Systems (GIS) analysis and PaleoGIS—which allows fossil locality positions to be viewed in the context of Cambrian palaeogeography—to quantitatively reconstruct geographic distribution patterns of primarily soft-bodied arthropod species. Further, we compare these patterns with those of co-occurring trilobite taxa. Soft-bodied Cambrian arthropods show both statistically larger geographic ranges and greater stratigraphic longevities than co-occurring trilobites. Many of the most widely distributed soft-bodied arthropods were likely capable of swimming, and this may in part explain their extensive distributions.

Palaeoceanography and biogeography in the Early Jurassic Panthalassa and Tethys Oceans

A first conceptual palaeoceanographic model for the Early Jurassic Panthalassa and Tethys Oceans is outlined in the present paper. The new palaeoceanographic model uses fundamental physic–oceanographic principles known from the modern world and a global palaeogeographic reconstruction for the Early Jurassic to examine the long-term response of the Panthalassic and Tethyan fossil invertebrate faunas to the proposed surface ocean circulation. Analysis of palaeobiogeographical data (ostracods, ammonites, brachiopods and bivalves) has enabled circulation changes to be reconstructed over the studied period in some detail. Panthalassic circulation pattern shows an almost hemispherical symmetric pattern, with the development of the two large subtropical gyres that rotates clockwise in the northern hemisphere and anti-clockwise in the southern hemisphere. Surface circulation in the Tethyan Ocean is dominated by monsoonal westerly-directed equatorial surface currents that reached its western corner and droved them off to the north, along the northern side of the Tethys Ocean, during summer and in opposite direction during the winter.

Fossil Folklore from India: The Siwalik Hills and the Mahâbhârata

All over the world, from antiquity to the present, people have often explained fossil discoveries as proof of the historical truth of legends and myths, or used them as a basis for a new legend. Most often, large vertebrate fossils have been explained as bones and teeth of giant humans, dragons and monsters, saints and heroes. Smaller invertebrate fossils were often interpreted as sacred or curious relics based on their resemblance to familiar or sacred objects. India is no exception to this practice. Fossil ammonites (salagramas), for example, are worshipped as the disc (chakra) of the Hindu god Vishnu. The Siwalik Hills, below the Himalayas, are strewn with impressive Plio-Pleistocene vertebrate fossils. This paper suggests that the region was seen as the historical stage for the legendary battle as described in the Indian epic Mahâbhârata, during which hundreds of mighty, and sometimes gigantic, heroes, horses, and war elephants are said to have died. Their remains are seen in the fossil bones, skulls, jaws, and tusks of hippopotamuses (Hexaprotodon), proboscideans (Stegodon, Archidiskodon), four-horned giraffes (Sivatherium, Giraffokeryx), giant tortoises (Geochelone), sabre-toothed cats (Paramachairodus), camels (Camelus), and other species found on the surface of the Siwalik Hills. Moreover, thousands of ancient bronze javelins and spears are also found there after rains. These archaeological artefacts, along with the paleontological remains, appear to have influenced the setting and context of the great battle in the Indian epic.

Stable isotopes in fossil mammals, fish and shells from Kunlun Pass Basin, Tibetan Plateau: Paleo-climatic and paleo-elevation implications

We report the results of a stable isotope study of a late Pliocene fauna recently discovered in the Kunlun Mountain Pass area (∼4700 m above sea level) on the northern Tibetan Plateau. The δ13C values of enamel samples from modern herbivores from the Kunlun Pass Basin range from −14.8 to −10.6‰, with a mean of −12.0±0.7‰, indicating pure C3 diets consistent with the current dominance of C3 vegetation in the area. In contrast, enamel samples from fossil herbivores yielded δ13C values of −5.4‰ to −10.2‰ (with a mean of −7.9±1.3‰), significantly higher than those of modern herbivores in the area. The higher δ13C values indicate that these ancient herbivores, unlike their modern counterparts, had a variety of diets ranging from pure C3 to mixed C3/C4 vegetation. The local ecosystems in the Kunlun Pass area in the late Pliocene likely included grasslands that had small amounts of C4 grasses. The δ18O values of enamel from large herbivores shifted to higher values after the late Pliocene, indicating a significant change in the δ18O of local meteoric water. We estimate that there has been approximately 3.2‰ increase in annual δ18O values of meteoric water since ∼2–3 Ma, most likely driven by changes in the regional hydrological cycle possibly as a result of tectonic and climate change. The δ18O values of fossil fish teeth/bones and gastropod shells, along with abundance of aquatic plants and other invertebrate fossils, clearly indicate that the Kunlun Pass Basin once had plenty of water and was occupied by a freshwater lake in the late Pliocene. Our isotope data from both terrestrial and aquatic fossils suggest that the Kunlun Pass Basin was a hospitable place with a much warmer and wetter climate in the late Pliocene, very different from today's rock desert and cold steppe environments. The mean annual temperature in the late Pliocene estimated from the δ18O of fossil bone carbonate and paleo-water was about 10±8 °C, much higher than the present-day mean annual temperature in the basin. If valid, the estimated temperature change would imply that the elevation of the basin has increased by ∼2700±1600 m since ∼2–3 Ma.

Ecosystem-wide body-size trends in Cambrian–Devonian marine invertebrate lineages

Fossil marine lineages are generally expected to exhibit long-term trends of increasing body size because of inherent fitness advantages or secular changes in environmental conditions. Because empirical documentation of this trend during the Paleozoic has been lacking for most taxonomic groups, the magnitude, timing, and taxonomic breadth of the trend have remained elusive. This study uses the largest existing database of fossil invertebrate sizes from four faunally important phyla to document ecosystem-wide size trends in well-preserved biotas from deep-subtidal, soft-substrate assemblages during the Cambrian through Devonian. Size of type specimens was measured along standard body axes from monographic plates and converted to body volume by using a broadly applicable empirical regression. Results demonstrate that mean body size (herein volume) of individual genera doubles during this interval, especially from the Late Ordovician through Early Devonian. The timing is gradual in spite of major radiations and extinctions, and the increase is primarily attributable to a net increase in the three-dimensionality of genera. The overall increase is not caused by replacement among clades because increases are widespread among arthropods, brachiopods, and echinoderms, at the phylum and class levels; in contrast, mollusks do not display a net size change at either taxonomic level. The increase is also more pronounced in microbivores than in carnivores. Combined with known environmental changes during this interval, and especially records of carbon dioxide, these trends provide support for the claim that primary productivity increased during the early to mid Paleozoic.

New York City Mastodons: Big Apple Tusks

Unlike some cities, New York is not known as a locality for fossils, and for good reason, they are few and far between, especially if you exclude the treasure trove of fossils embedded in the dimension stone of facades, lobbies, and rest rooms. It is easy to understand why New York City offers such a paucity of naturally occuring specimens when you consider that most of the city’s bedrock is composed of high-grade metamorphics—gneiss, marble, and schist—1.1 billion to 435 million years old (Baskerville 1994). Any fossils that may have existed in the original parent rock have been destroyed by ensuing high-grade metamorphism, a process by which rocks are altered by heat and/or pressure. The only exposed sedimentary rocks are Cretaceous-age clays and sands. In the past, they have yielded plant fragments including lignite and a few invertebrates (Hollick 1908) and some microfossils, but these exposures are substantially diminished with continuing urbanization. However, almost the entire city has been glaciated, and in places the veneer of glacially transported rocks yield a variety of Paleozoic invertebrate fossils delivered from north and west of the city (Hollick 1893). But it also turns out that late glacial and/or early post glacial sediments contain relatively rare fragments of mastodon skeletons—the ice-age elephant (Mammut americanum)—and finding them is a hit-or-miss undertaking. I have chosen the mastodon for this discussion, focusing on New York City as an unusual locality, because mastodon fossils are well distributed throughout North America, its fossils have been collected by the thousands (Haynes 1991), and mastodons were the rage long before dinosaurs were discovered. The fact that these animals roamed what is now Broadway is an excellent example for starting a discussion on climatic change as well as the hot topic of what caused the demise of the charismatic late Pleistocene megafauna and, as we will see, introducing some aspects of the history of paleontology. Another purpose of this paper is to show that the study of paleontology and evolution can and should be interdisciplinary and multidisciplinary. Often, it is the secondary aspects of these subjects that can excite students and gain their interest. Based on the plant material associated with mastodon fossils in northeastern United States, the mastodons clearly lived in spruce forests and open spruce woodlands containing swamps and bogs. Although the stratigraphic record is not very good for New York City localities, it can be assumed that they lived in a similar vegetation zone, an environment so different than the eastern deciduous forest that exists now in New York City. Today, there are remnants of this forest still extant, not only altered by many introduced species, but also not a true virgin forest because during the occupation by British and Hessian armies during the American Revolution the forests were entirely cut down on Manhattan Island to provide firewood and construction materials. The forest of the present time reestablished itself in many places with the withdrawal of the foreign troops. As most of the glacial deposits are covered by buildings or located in the adjacent waterways that make New York City an archipelago, finding fossils requires diligence at construction sites where, in general, the focus has been on Evo Edu Outreach (2008) 1:204–209 DOI 10.1007/s12052-008-0042-y

Sampling-standardized expansion and collapse of reef building in the Phanerozoic

Abstract. Tracing the variability of reef production over long temporal scales is important to approach natural processes favoring or suppressing reef growth. Raw compilations of reef abundance per unit of time do not necessarily depict biologically meaningful patterns, because the waxing and waning of reefs might just follow the quality of the fossil record, that is, the amount of paleontological information that is available in general. Here I standardize the published record of Phanerozoic reefs, as stored in the PaleoReefs database, to the published record of marine invertebrate fossils as stored in the Paleobiology Database. The sampling-standardized peaks in reef growth are essentially identical to those of previous studies, but significant peaks are rare. Times when unusual changes in ecological conditions are likely to control changes in metazoan reef proliferation were identified in the Late Devonian, Late Triassic, Late Jurassic and Neogene. doi: 10.1002/mmng.200700008

Sampling-standardized expansion and collapse of reef building in the Phanerozoic

Tracing the variability of reef production over long temporal scales is important to approach natural processes favoring or suppressing reef growth. Raw compilations of reef abundance per unit of time do not necessarily depict biologically meaningful patterns, because the waxing and waning of reefs might just follow the quality of the fossil record, that is, the amount of paleontological information that is available in general. Here I standardize the published record of Phanerozoic reefs, as stored in the PaleoReefs database, to the published record of marine invertebrate fossils as stored in the Paleobiology Database. The sampling-standardized peaks in reef growth are essentially identical to those of previous studies, but significant peaks are rare. Times when unusual changes in ecological conditions are likely to control changes in metazoan reef proliferation were identified in the Late Devonian, Late Triassic, Late Jurassic and Neogene. <br><br> doi:<a href="http://dx.doi.org/10.1002/mmng.200700008" target="_blank">10.1002/mmng.200700008</a>

Three-dimensional Magnetic Resonance Imaging of fossils across taxa

Abstract. The frequency of life forms in the fossil record is largely determined by the extent to which they were mineralised at the time of their death. In addition to mineral structures, many fossils nonetheless contain detectable amounts of residual water or organic molecules, the analysis of which has become an integral part of current palaeontological research. The methods available for this sort of investigations, though, typically require dissolution or ionisation of the fossil sample or parts thereof, which is an issue with rare taxa and outstanding materials like pathological or type specimens. In such cases, non-destructive techniques could provide a valuable methodological alternative. While Computed Tomography has long been used to study palaeontological specimens, a number of complementary approaches have recently gained ground. These include Magnetic Resonance Imaging (MRI) which had previously been employed to obtain three-dimensional images of pathological belemnites non-invasively on the basis of intrinsic contrast. The present study was undertaken to investigate whether 1H MRI can likewise provide anatomical information about non-pathological belemnites and specimens of other fossil taxa. To this end, three-dimensional MR image series were acquired from intact non-pathological invertebrate, vertebrate and plant fossils. At routine voxel resolutions in the range of several dozens to some hundreds of micrometers, these images reveal a host of anatomical details and thus highlight the potential of MR techniques to effectively complement existing methodological approaches for palaeontological investigations in a wide range of taxa. As for the origin of the MR signal, relaxation and diffusion measurements as well as 1H and 13C MR spectra acquired from a belemnite suggest intracrystalline water or hydroxyl groups, rather than organic residues.