David Peterman

Pennsylvania State University | Penn State · Department of Mechanical and Nuclear Engineering

A remarkable variety of organisms use metachronal coordination (i.e., numerous neighboring appendages beating sequentially with a fixed phase lag) to swim or pump fluid. This coordination strategy is used by microorganisms to break symmetry at small scales where viscous effects dominate and flow is time-reversible. Some larger organisms use this sw...

A remarkable variety of organisms use metachronal coordination (i.e., numerous neighboring appendages beating sequentially with a fixed phase lag) to swim or pump fluid. This coordination strategy is used by microorganisms to break symmetry at small scales where viscous effects dominate and flow is time-reversible. Some larger organisms use this sw...

This is a report on a marine assemblage of chondrichthyans and other vertebrates from the early Permian aged Lueders Formation, which is part of Texas' Permian Basin.

Bonebeds occurring in exposures of the Burlington and Keokuk Limestones (Mississippian/Osagean) along the Iowa and Illinois border (USA) contain an abundant and diverse collection of chondrichthyan remains that includes teeth, spines, denticles, and coprolites. These remains represent cochliodont, hybodont, petalodont, ctenacanthid, symmoriid, and...

Strophomenoid brachiopods had thin, concavo‐convex shells, were ubiquitous colonizers of Palaeozoic muddy seafloors, and are hypothesized to have filter‐fed in a concave‐upward orientation. This orientation would elevate their line of commissure out of potentially lethal lophophore‐clogging mud. The paradox is that epibiont distributions on stropho...

Ctenophores (comb jellies) were among the first swimming animals, and offer perspectives into the evolution of unique locomotion strategies. These animals bear the largest cilia of any organisms (~1 mm), which are bundled into paddle-like structures (ctenes) and arranged in rows around the body. These arrays of propulsors beat metachronally, enabli...

Flexibility is a key feature of biological structures involved in swimming and flying, enhancing efficiency and performance. Advances in soft robotics enable engineering solutions that can more closely mimic such structures compared to rigid mechanical designs, helping us explore the role of flexibility across a range of biological and hydrodynamic...

The use of bioinspired soft actuators and soft robotics has increased in recent years. Compared to rigid mechanical designs, these approaches offer flexible engineering solutions that better approximate the movement of many biological structures. A ubiquitous flexible structure is the cilium, which plays an important role in a variety of functional...

Synopsis 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.g., ammonoids and nautiloids) are excellent targets to study physical tr...

The fossil record represents the world’s largest historical dataset of biodiversity. However, the biomechanical and ecological potential of this dataset has been restricted by various unique barriers obstructing experimental study. Fossils are often partial, modified by taphonomy, or lacking modern analogs. In the past, these barriers confined many...

Synopsis 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...

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...

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...

The Bobcat (Lynx rufus: Carnivora, Felidae) is considered a rare species in the lands that make up the state of Ohio. Traditionally, the late-Holocene history of this animal is thought involve an extirpation period beginning around 1850 CE and a gradual reintroduction from around 1950 to 1970 CE. A radiocarbon test from a bobcat-containing cave ass...

Biomechanical analyses provide unique insights on state shifts in the ecology of extinct communities. Ammonoids present a compelling case study for coupling biomechanical analysis with ecology given their robust fossil record of external conchs. We present a trajectory model to evaluate hydrodynamical advantages and challenges associated with ammon...

Externally shelled cephalopods (nautiloids and ammonoids) underwent seemingly endless variations in shell shape throughout their extensive evolutionary history. Similarities in gross external shape have invited comparisons in life modes and swimming capabilities with both extant coleoids (squid, cuttlefish, etc.) and nautilids (e.g., Nautilus). All...

Among marine organisms, externally shelled cephalopods have evolved unique solutions to locomotion and buoyancy management, becoming dominant components of marine ecosystems for much of the current eon. Today, cephalopods are the most complex and mobile group of mollusks, yet the swimming capabilities and life habits of extinct morphologies are poo...

Recent advances in digital biomechanical tools (Computational Fluid Dynamics; Finite Element Analysis; Motion Capture) have enriched the of study morphological performance while yielding a daunting volume of data. Traditional hypothesis testing may posit one functional scenario at a time: e.g., which shelled mollusk has the lowest drag, the greates...

Karst features in the Silurian dolomites of Taylorsville MetroPark (Dayton Metropolitan Area, Ohio, United States) were explored from 2017 to 2018 to identify sites of paleontological interest. Initial landscape surveys recovered 124 skeletal elements (from 12 sites) that were attributed to 17 vertebrate species—including evidence of such extirpate...

The Ordovician rocks on the north-central portion of the North American craton produce many examples of nautiloid and endoceratoid cephalopods which grow to lengths far in excess of almost all modern members of the Cephalopoda. Initial surveys of invertebrate fossils from Middle to Late Ordovician rocks in Michigan’s Upper Peninsula yield similar o...

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, phylogen...

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 ha...

For centuries, paleontologists have sought functional explanations for the uniquely complex internal walls (septa) of ammonoids, extinct shelled cephalopods. Ammonoid septa developed increasingly complex fractal margins, unlike any modern shell morphologies, throughout more than 300 million years of evolution. Some have suggested these morphologies...

Of the many shell morphologies produced by ammonoid cephalopods, the helical torticone shape appears poorly-suited to rapid locomotion. We investigate torticone hydrostatics and hydrodynamics through virtual modeling, computational fluid dynamics simulations, and water-chamber experiments, using the Cenomanian (Cretaceous) turrilitid Mariella brazo...

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...

The peculiar high-spired coils of torticone ammonoid shells present distinct challenges, and advantages, for the potential locomotion of these extinct cephalopods. Ecological consequences for this shell shape are particularly relevant to re-creations of Cretaceous habitats, due to the abundance, diversity, and cosmopolitan distribution of Turriliti...

I´ve recently reupload the video, the new video tutorial link: https://youtu.be/Zos6oQYOSNE

The biomechanics of uncoiled heteromorph ammonoids with body chambers that terminate in U-shaped hooks (ancylocones) were investigated with virtual and physical models of Audouliceras renauxianum. Virtual models were used to compute the hydrostatic properties of this morphotype. Audouliceras has the capacity for neutral buoyancy and this suggests t...

Computed tomography has provided a wealth of biological data that now stands beside a vast, more traditional, morphometric database. By exploiting these two resources, we present a novel methodology to construct intricate, virtual cephalopod shells. As a case of study, we applied this method to Maorites seymourianus using data obtained from a previ...

Nipponites is a heteromorph ammonoid with a complex and unique morphology that obscures its mode of life and ethology. The seemingly aberrant shell of this Late Cretaceous nostoceratid seems deleterious. However, hydrostatic simulations suggest that this morphology confers several advantages for exploiting a quasi-planktic mode of life. Virtual, 3D...

The late Mesoproterozoic to early Neoproterozoic Middle Run Formation contains vital information about the crustal evolution of the North American Craton. Four reprocessed seismic reflection lines in the vicinity of the AK Steel facility in Middletown, Ohio, provide new insights into the structural and depositional setting of the Middle Run Formati...

Nipponites is a heteromorph ammonoid with a complex and unique morphology that obscures its mode of life and ethology. The seemingly aberrant shell of this Late Cretaceous nostoceratid seems deleterious. However, hydrostatic simulations suggest that this morphology confers several advantages for exploiting a quasi-planktic mode of life. Virtual, 3D...

This abstract reports on a previously studied vertebrate locality along the Kansas-Oklahoma border. New reports of taxa from this site indicate that the limestone from this region and time had a much higher species-richness than previously thought. These new reports also fill in gaps in our understandings of the biogeography of many marine vertebra...

Ectocochleate cephalopods have external shells filled with divider walls called septa. Ammonoid cephalopods had complex, marginally frilled septa that have been subjected to many hypotheses regarding possible biological functions. Among these hypotheses is the retention of chamber liquid via surface tension. The relative amount of liquid retained b...

Scaphitid ammonoids were ubiquitous and significant components of the Western Interior Seaway during the Late Cretaceous. This group is characterized by a recurved hook at maturity that deviates from the juvenile whorls. Such a modification seems counterproductive to active locomotion and to manage a biologically effective orientation that facilita...

The seemingly aberrant coiling of heteromorphic ammonoids suggests that they underwent more significant changes in hydrostatic properties throughout ontogeny than their planispiral counterparts. Such changes may have been responses to different selective pressures at different life stages. The hydrostatic properties of three species of Didymoceras...

The lower Pleistocene Waccamaw Formation of northeastern South Carolina and southeastern North Carolina is recently understood to contain at least ten species of echinoids making it the most diverse Pleistocene echinoid fauna along the east coast of North America. An exposure along the Intracoastal Waterway in North Myrtle Beach, South Carolina dis...

This manuscript, which will later be published in the journal Southeastern Geology, is the first report of a lower Permian (Artinskian) molluscan community, and the stratigraphy and biogeography associated with the community.

The boundary between the Permian and Triassic Periods represents the most severe global extinction event to have occurred during the Phanerozoic Eon. This extinction event led to the loss of an estimated 70% of land-based species and over 90% of marine species, and paved the way for the appearance of new groups in the Mesozoic and Cenozoic Eras. Ch...

This is a pop-science article, written by myself and David Peterman for The Professional Geologist: a magazine published by AIPG, the American Institute for Professional Geology

Hydrodynamic analyses of heteromorphic ammonoids with U-shaped body chambers reveal that they are very stable, yet can assume speeds similar to those of the Nautilus (and lower depending the metrics of thrust efficiency).

Theoretical 3D models were digitally reconstructed from a phragmocone section of Baculites compressus in order to investigate the hydrostatic properties of the orthoconic morphotype. These virtual models all had the capacity for neutral buoyancy (or nearly so) and were highly stable with vertical syn vivo orientations. Body chamber lengths exceedin...

Scaphitid ammonoids exhibit a considerable amount of sexual dimorphism in shell morphology between micro- and macroconchs (interpreted as males and females, respectively). These dimorphic pairs are particularly different for Hoploscaphites crassus. At maturity, both micro- and macroconchs of this species consist of a planispiral and somewhat involu...

A 2-D fractal wire antenna is a fractal (self-similar) shape that can receive and transmit electromagnetic radiation. 2-D fractals are shapes that increase in length with each iteration and at their mathematical limit (of infinite iterations) have an infinite length. The fractal dimension describes the degree of space filling. A fundamental propert...

The exposures of the Maquoketa Formation near Dubuque, Iowa have attracted interest for both their remarkably concentrated Ordovician cephalopod assemblage and their excellent fossil preservation: the phragmocones exhibit the oldest preserved cephalopod nacre yet discovered. The most common cephalopod phragmocones found here are from Isorthoceras s...

Heteromorphic ammonites (which exhibit irregular or non-planispiral coiling) are enigmatic in terms of their habit and paleoecological roles. This is especially true for the genus Didymoceras, which is characterized by a variable juvenile stage, followed by a torticonic (corkscrew) intermediate stage, then termination with a U-shaped hook. While Di...

The spatial scaling of 77 hemisutures from 65 species of Cretaceous heteromorphic ammonites was quantified with the fractal box‐counting method. Fractal dimensions within Baculites compressus did not significantly differ between adult hemisutures; however, the juvenile suture of this species did exhibit a significantly lower fractal dimension. This...

During the Early Ordovician, diversification of nautiloid cephalopods led to an increased occupation of the pelagic zone. Small longiconic and cyrtoconic nautiloids (Ellesmerocerida) dominated during the Upper Cambrian and almost exclusively inhabited the neritic zone. In the Early Ordovician, new orders appeared (including the Endocerida and Ortho...

Ectocochleate (external) cephalopod shells are comprised of a body chamber which houses the organisms soft parts and the phragmocone which consists of a series of progressively larger chambers (camerae) divided by septa. The phragmocone is used as a passive gas float for buoyancy regulation. The soft body and the mineralized shell are denser than w...

The reprocessing of four seismic reflection lines at the AK Steel facility in Middletown, Ohio, provides new insight on the age, deposition, and structural deformation of the Middle Run Formation in southwest Ohio. A new residual statics solution improved the resolution and coherency of pre-Mt. Simon reflectors. Processing focused on pre-Mt. Simon...

Geophysical techniques are vital in understanding the upper crust across the U.S. midcontinent. We interpret four 2-D seismic reflection surveys provided by CountryMark to analyze pre-Mt. Simon seismic stratigraphy below west-central Indiana. Analyzing these data hold implications for understanding of Precambrian to early Cambrian Laurentian crusta...

The spatial scaling of suture patterns from 44 ammonite species of the suborder Ancyloceratina was measured using the fractal box counting method. These specimens were selected from every stage in the Cretaceous and range between approximately 145 Ma to 66 Ma in age. The sutures analyzed in this study were found from published literature where half...