Benjamin Linzmeier

University of South Alabama | USA · Department of Earth Sciences

Carbon dioxide release during Deccan Traps volcanism and the Chicxulub impact likely contributed to the Cretaceous-Paleogene (K-Pg) mass extinction; however, the intensity and duration of CO2 input differed between the two events. Large and rapid addition of CO2 to seawater causes transient decreases in pH, [CO32–], and carbonate mineral saturation...

Ediacaran-aged (635–541 million years ago) marine sediments contain a large negative carbon isotope (δ13C) excursion, in which carbonate δ13C values reach −12‰ (VPDB). Known as the ‘Shuram’ excursion, many workers have interpreted this δ13C record as an unprecedented perturbation to the global carbon cycle, leading to speculation about a causal con...

Cephalopod carbonate geochemistry underpins studies ranging from Phanerozoic, global-scale change to outcrop-scale paleoecological reconstructions. Interpreting these data hinges on assumed similarity to model organisms, such as Nautilus , and generalization from other molluscan biomineralization processes. Aquarium rearing and capture of wild Naut...

The biogeography of terrestrial amniotes is controlled by historical contingency interacting with paleoclimate, morphology and physiological constraints to dispersal. Thermal tolerance is the intersection between organismal requirements and climate conditions which constrains modern organisms to specific locations and was likely a major control on...

The giant squid (Architeuthis dux) is the largest living marine invertebrate. Genetic evidence suggests there is a single, globally distributed species. In order to sustain a globally connected population, dispersal of individuals must happen regularly. In many other deep-sea cephalopods, juvenile dispersal though a planktic phase is critical. Alth...

Paleotemperatures based on δ18O values derived from belemnites are usually “too cold” compared to other archives and paleoclimate models. This temperature bias represents a significant obstacle in paleoceanographic research. Here we show geochemical evidence that belemnite calcite fibers are composed of two distinct low-Mg calcite phases (CP1, CP2)...

Heteromorphs are ammonoids forming a conch with detached whorls (open coiling) or non-planispiral coiling. Such aberrant forms appeared convergently four times within this extinct group of cephalopods. Since Wiedmann's seminal paper in this journal, the palaeobiology of heteromorphs has advanced substantially. Combining direct evidence from their f...

High Spatial-resolution Assessment of Diagenesis and Primary Isotopic Variability in Maastrichtian Molluscan Carbonates from Antarctica - Benjamin Linzmeier, Thomas Tobin, Peter Ward, Ian Orland, Daniella Assing, Kouki Kitajima, Phillip Gopon, Brian Huber, Shanan Peters, John Valley

We employed the widely-tested biophysiological modeling software, Niche Mapper™ to investigate the metabolic function of the Late Triassic dinosaurs Plateosaurus and Coelophysis during global greenhouse conditions. We tested a variety of assumptions about resting metabolic rate, each evaluated within six microclimate models that bound paleoenvironm...

We employed the widely-tested biophysiological modeling software, Niche Mapper™ to investigate the metabolic function of Late Triassic dinosaurs Plateosaurus and Coelophysis during global greenhouse conditions. We tested them under a variety of assumptions about resting metabolic rate, evaluated within six microclimate models that bound paleoenviro...

Serially sampled oxygen isotope ratios (δ18O) from fossil and modern cephalopods may provide new insight into the behavior and longevity of individuals. Interpretation of these data is generally more difficult than similar data from bivalves or brachiopods because the measured δ18O from shell combines both seasonal change and depth change over the...

Ammonites have disparate adult morphologies indicative of diverse ecological niches, but ammonite hatchlings are small (~1 mm diameter), which raises questions about the similarity of egg incubation and hatchling life mode in ammonites. Modern Nautilus is sometimes used as a model organism for understanding ammonites, but despite their outward simi...

Serially sampled δ18O from fossil and modern cephalopods may provide new insight into the behavior and longevity of individuals. Interpretation of these data is generally more difficult than similar data from bivalves or brachiopods because the measured δ18O from shell combines both seasonal change and depth change over the life of an individual. I...

Researchers on the cutting edge of geochemistry are tracing Earth’s history through the clues recorded in tiny mineral crystals. Often, they must work with the microscopic (or nanoscopic) features in rare, hard-won specimens to pull apart the complete history of the mineral’s formation. Even in large pieces of rock, microscopic variability may be d...

Carbonate skeletons of fossil marine organisms are widely used for the reconstruction of past environments. Specifically , the geochemistry of Jurassic and Cretaceous belemnite rostra, a mineralized internal structure, is commonly applied to reconstruct paleoseawater properties. The low-Mg calcite rostra are commonly assumed to be precipitated in o...

Carbonate skeletons of fossil marine organisms are widely used for the reconstruction of past environments. The geochemistry of Jurassic and Cretaceous belemnite rostra, a mineralized internal structure, is commonly applied to reconstruct palaeoseawater properties such as surface temperature from oxygen isotope ratios. The low-Mg calcite rostra are...

Ammonites are the most iconic of extinct mollusks. Their wide spatial distribution and biostratigraphic utility make them ideally suited to investigate past climate. To date, stable isotope analyses of ammonites have focused on adult shells that can be sampled by bulk methods and have suggested adults had a nektobenthic mode of life. Eggs and hatch...

The strong contrast between egg size and hatchling ecology of ammonoids and nautiloids is thought to explain why ammonoids were more vulnerable to extinction and more prone to diversification than nautiloids throughout the fossil record. Nautiloids had large slowly developing eggs (20-30 mm) and nektobenthic juveniles and ammonoids had small eggs (...

Local geological knowledge is usually not highlighted in general geology textbooks that are used in high schools, and thus they do not incorporate hands-on learning opportunities that can engage and inspire new geologists. University faculty with expertise in local geology can disseminate knowledge, but must balance outreach with the demands of tea...

Carbonate skeletons of fossil marine organisms are widely used to reconstruct palaeoceanographic parameters. Specifically, the geochemistry of Jurassic and Cretaceous belemnite rostra is traditionally interpreted to represent near sea-surface seawater properties. More recently, an increasing number of workers, have reported significant scatter in g...

Nautilus is often used as an analogue for the ecology and behavior of extinct externally shelled cephalopods. Nautilus shell grows quickly, has internal growth banding, and is widely believed to precipitate aragonite in oxygen isotope equilibrium with seawater. Pieces of shell from a wild-caught Nautilus macromphalus from New Caledonia and from a N...

SEM and CLFM images of transects on Nautilus belauensis, AMNH 102555. (PDF)

Table of all SIMS analyses including rejected values for sample Nautilus macromphalus, AMNH 105621. Complete data table of analyses in the outer prismatic layer of the wild-caught Nautilus macromphalus including bracketing standards and aragonite standard. (XLSX)

Table of all SIMS analyses including rejected values for sample Nautilus belauensis, AMNH 102555. Complete data table of analyses in the outer prismatic layer of the aquarium-reared Nautilus belauensis including bracketing standards and aragonite standard. (XLSX)

Recent work suggests that the Chicxulub bolide impact was not the only significant mechanism driving the Cretaceous-Paleogene (K/Pg) mass extinction event (~65.5 Ma) and that there must have been several other mechanisms including climate change which also contributed to this event. The sequence, nature and magnitude of climate change approaching t...

In situ microanalytical techniques have become faster, more precise, and have seen wider use in the geosciences over the last two decades. Individual 2.5 cm diameter samples may have large data sets from in situ microanalytical instruments (e.g. SIMS, EPMA, LA-MS) and suites of images from multiple techniques (e.g. cross polarized light, plane pola...

General geology textbooks used in high schools have a global or national audience, and thus do not incorporate opportunities for hands-on local scientific inquiry that greatly benefit the learning experience. University geoscientists with expertise in local geology can disseminate knowledge to high schools, but must balance such outreach with other...

The Buckhorn Asphalt quarry, south of Sulfur, Oklahoma in the Arbuckle Mountains, contains an asphalt-impregnated fossil Lagerstätte that preserves the original aragonite mineralogy of a diverse middle Pennsylvanian (Desmoinesian) marine assemblage dominated by molluscs. Orthoconic nautiloids are preserved as segments of the phragmocone and are ver...