Stability-Maneuverability Tradeoffs Provided Diverse Functional Opportunities to Shelled Cephalopods.

Stability-maneuverability tradeoffs impose various constraints on aquatic locomotion. The fossil record houses a massive morphological dataset that documents how organisms have encountered these tradeoffs in an evolutionary framework. Externally shelled cephalopods (e.

Resurrecting extinct cephalopods with biomimetic robots to explore hydrodynamic stability, maneuverability, and physical constraints on life habits.

Externally shelled cephalopods with coiled, planispiral conchs were ecologically successful for hundreds of millions of years. These animals displayed remarkable morphological disparity, reflecting comparable differences in physical properties that would have constrained their life habits and ecological roles. To investigate these constraints, self-propelling, neutrally buoyant, biomimetic robots were 3D-printed for four disparate morphologies.

Detecting Mismatch in Functional Narratives of Animal Morphology: a Test Case With Fossils.

A boom in technological advancements over the last two decades has driven a surge in both the diversity and power of analytical tools available to biomechanical and functional morphology research. However, in order to adequately investigate each of these dense datasets, one must often consider only one functional narrative at a time. There is more to each organism than any one of these form-function relationships.

The limits of convergence: the roles of phylogeny and dietary ecology in shaping non-avian amniote crania.

Cranial morphology is remarkably varied in living amniotes and the diversity of shapes is thought to correspond with feeding ecology, a relationship repeatedly demonstrated at smaller phylogenetic scales, but one that remains untested across amniote phylogeny. Using a combination of morphometric methods, we investigate the links between phylogenetic relationships, diet and skull shape in an expansive dataset of extant toothed amniotes: mammals, lepidosaurs and crocodylians. We find that both phylogeny and dietary ecology have statistically significant effects on cranial shape.

Vertical escape tactics and movement potential of orthoconic cephalopods.

Measuring locomotion tactics available to ancient sea animals can link functional morphology with evolution and ecology over geologic timescales. Externally-shelled cephalopods are particularly important for their central roles in marine trophic exchanges, but most fossil taxa lack sufficient modern analogues for comparison. In particular, phylogenetically diverse cephalopods produced orthoconic conchs (straight shells) repeatedly through time.

Buoyancy control in ammonoid cephalopods refined by complex internal shell architecture.

The internal architecture of chambered ammonoid conchs profoundly increased in complexity through geologic time, but the adaptive value of these structures is disputed. Specifically, these cephalopods developed fractal-like folds along the edges of their internal divider walls (septa). Traditionally, functional explanations for septal complexity have largely focused on biomechanical stress resistance.

Assessing the Morphological Impacts of Ammonoid Shell Shape through Systematic Shape Variation.

A substantial body of research has been accumulated around ammonoids over several decades. A core aspect of this research has been attempting to infer their life mode from analysis of the morphology of their shells and the drag they incur as that shell is pushed through the water. Tools such as Westermann Morphospace have been developed to investigate and scaffold hypotheses about the results of these investigations.

Microbial-caddisfly bioherm association from the Lower Cretaceous Shinekhudag Formation, Mongolia: Earliest record of plant armoring in fossil caddisfly cases.

Caddisfly larvae construct underwater protective cases using surrounding materials, thus providing information on environmental conditions in both modern and ancient systems. Microbial bioherms associated with caddisfly cases are found in the Berriassian-Hauterivian (~140-130 Ma) Shinekhudag Formation of Mongolia, and yield new insights into aspects of lacustrine paleoecosystems and paleoenvironments. This formation contains the earliest record of plant-armored caddisfly cases and a rare occurrence of microbial-caddisfly association from the Mesozoic.

Mercury anomalies and the timing of biotic recovery following the end-Triassic mass extinction.

The end-Triassic mass extinction overlapped with the eruption of the Central Atlantic Magmatic Province (CAMP), and release of CO2 and other volcanic volatiles has been implicated in the extinction. However, the timing of marine biotic recovery versus CAMP eruptions remains uncertain. Here we use Hg concentrations and isotopes as indicators of CAMP volcanism in continental shelf sediments, the primary archive of faunal data.