About
39
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Introduction
David M Grossnickle is an Assistant Professor in the Natural Sciences Department at Oregon Institute of Technology. David does research in comparative anatomy, mammalogy, evolutionary biology, functional morphology, and paleobiology, .
Current institution
Additional affiliations
September 2023 - present
Oregon Institute of Technology
Position
- Assistant Professor
March 2018 - present
August 2007 - June 2011
Wawasee High School
Position
- High school biology teacher
Education
September 2013 - March 2018
August 2011 - May 2013
August 1999 - May 2003
Publications
Publications (39)
It is often postulated that mammalian diversity was suppressed during the Mesozoic Era and increased rapidly after the Cretaceous–Palaeogene (K– Pg) extinction event.We test this hypothesis by examining macroevolutionary patterns in early therian mammals, the group that gave rise to modern placentals and marsupials. We assess morphological disparit...
The ecological diversification of early mammals is one of the most globally transformative
events in Earth’s history and the Cretaceous Terrestrial Revolution
(KTR) and end-Cretaceous mass extinction are commonly hailed as catalysts.
However, a confounding issue when examining this diversification is that it
comprised nested radiations of mammalian...
Ecological specialization is a central driver of adaptive evolution. However, selective pressures may uniquely affect different ecomorphological traits (e.g., size and shape), complicating efforts to investigate the role of ecology in generating phenotypic diversity. Comparative studies can help remedy this issue by identifying specific relationshi...
Ecology and biomechanics play central roles in the generation of phenotypic diversity. When unrelated taxa invade a similar ecological niche, biomechanical demands can drive convergent morphological transformations. Thus, identifying and examining convergence helps to elucidate the key catalysts of phenotypic change. Gliding mammals are often prese...
Theria comprises all but three living mammalian genera and is one of the most ecologically pervasive clades on Earth. Yet, the origin and early history of therians and their close relatives (i.e., cladotherians) remains surprisingly enigmatic. A critical biological function that can be compared among early mammal groups is mastication. Morphometric...
Bats are the only mammals capable of powered flight and have correspondingly specialized body plans, particularly in their limb morphology. The origin of bat flight is still not fully understood due to an uninformative fossil record but, from the perspective of a functional transition, it is widely hypothesized that bats evolved from gliding ancest...
Tests of phenotypic convergence can provide evidence of adaptive evolution, and the popularity of such studies has grown in recent years due to the development of novel, quantitative methods for identifying and measuring convergence. These methods include the commonly applied C1–C4 measures of Stayton (2015), which measure morphological distances b...
Adaptive radiations are bursts in biodiversity that generate new evolutionary lineages and phenotypes. However, because they typically occur over millions of years, it is unclear how their macroevolutionary dynamics vary through time and among groups of organisms. Phyllostomid bats radiated extensively for diverse diets—from insects to vertebrates,...
Metatherian mammals were taxonomically rich and abundant in Late Cretaceous faunas of North America. Although much attention has been paid to metatherian taxonomy, a comprehensive, quantitative study on the ecomorphology of this clade is lacking. Here, we predict the diets of a large sample of metatherians using three-dimensional dental topographic...
Evolutionary radiations generate most of Earth’s biodiversity, but are there common ecomorphological traits among the progenitors of radiations? In Synapsida (the mammalian total group), ‘small-bodied faunivore’ has been hypothesized as the ancestral state of most major radiating clades, but this has not been quantitatively assessed across multiple...
Adaptive radiations are bursts in biodiversity that lead to the origin of new evolutionary lineages and phenotypes. However, adaptive radiations typically occur over millions of years and it is unclear how the macroevolutionary dynamics that underpin them vary through time and among groups of organisms. Phyllostomid bats radiated extensively for di...
The skull shapes of mammals diversified more rapidly early in their history.
Tests of phenotypic convergence can provide evidence of adaptive evolution, and the popularity of such studies has grown in recent years due to the development of novel, quantitative methods for identifying and measuring convergence. These methods include the commonly applied C 1– C 4 measures of Stayton (2015), which measure morphological distance...
Bats are the only mammals capable of powered flight and have correspondingly specialized body plans, particularly in their limb morphology. The evolution of bat flight is still not fully understood due to an uninformative fossil record, but it is widely hypothesized that flying evolved from gliding. Here, we test the gliding to flying hypothesis of...
The remarkable evolutionary success of placental mammals has been partly attributed to their reproductive strategy of prolonged gestation and birthing of relatively precocial, quickly weaned neonates. Although this strategy was conventionally considered derived relative to that of marsupials with highly altricial neonates and long lactation periods...
The evolution of complex dentitions was a major innovation in mammals that facilitated the expansion into new dietary niches that imposed selection for tight form-function relationships. Teeth allow mammals to ingest and process food items by applying forces produced by a third-class lever system composed by the jaw adductors, the cranium, and the...
Evolutionary radiations generate most of Earth’s biodiversity, but are there common ecomorphological traits among the progenitors of radiations? In Synapsida (mammalian total group), ‘small-bodied faunivore’ has been hypothesized as the ancestral state of most major radiating clades, but this has not been quantitatively assessed across multiple rad...
Extant marsupials are less ecologically diverse than placentals, and this is reflected by placentals exhibiting a greater diversity of locomotor modes, including powered flight and fully aquatic swimming. One proposed explanation for this discrepancy is that the development of more disparate marsupial forelimbs is prevented by the neonate’s crawl t...
In non-mammalian synapsids and early mammals, evolutionary transformations in the feeding and hearing apparatuses are posited to have been prerequisites for the radiation of extant mammals. Unlike most vertebrates, including many early synapsids, mammals have precise dental occlusion, a lower jaw composed of one bone, and middle ear ossicles derive...
Extant marsupials are less ecologically diverse than placentals, and this is reflected by placentals exhibiting a greater diversity of locomotor modes, including powered flight and fully aquatic swimming. One proposed explanation for this discrepancy is that the development of more disparate marsupial forelimbs is prevented by the neonate's crawl t...
Selective pressures favor morphologies that are adapted to distinct ecologies, resulting in trait partitioning among ecomorphotypes. However, the effects of these selective pressures vary across taxa, especially because morphology is also influenced by factors such as phylogeny, body size, and functional trade-offs. In this study, we examine how th...
The asterisked footnote to Extended Data Table 1 should state '*Including Thomasia and Haramiyavia'. This has been corrected online.
Haramiyida was a successful clade of mammaliaforms, spanning the Late Triassic period to at least the Late Jurassic period, but their fossils are scant outside Eurasia and Cretaceous records are controversial1-4. Here we report, to our knowledge, the first cranium of a large haramiyidan from the basal Cretaceous of North America. This cranium posse...
Identification of locomotor modes in fossil taxa is critical for assessing paleoecological diversity. This is especially relevant for early mammaliaforms, since they were historically stereotyped as terrestrial generalists with limited ecological diversity. Recently described fossils have challenged this stereotype by demonstrating considerable eco...
Stem mammaliaforms are forerunners to modern mammals, and they achieved considerable ecomorphological diversity in their own right. Recent discoveries suggest that eleutherodontids, a subclade of Haramiyida, were more species-rich during the Jurassic period in Asia than previously recognized. Here we report a new Jurassic eleutherodontid mammaliafo...
Stem mammaliaforms are Mesozoic forerunners to mammals, and they offer critical evidence for the anatomical evolution and ecological diversification during the earliest mammalian history. Two new eleutherodonts from the Late Jurassic period have skin membranes and skeletal features that are adapted for gliding. Characteristics of their digits provi...
A new docodontan mammaliaform from the Middle Jurassic of China has skeletal features for climbing and dental characters indicative of an omnivorous diet that included plant sap. This fossil expands the range of known locomotor adaptations in docodontans to include climbing, in addition to digging and swimming. It further shows that some docodontan...
Fossil discoveries over the past 30 years have radically transformed traditional views of Mesozoic mammal evolution. In addition, recent research provides a more detailed account of the Cretaceous diversification of flowering plants. Here, we examine patterns of morphological disparity and functional morphology associated with diet in early mammals...
