About

Kevin Boyce is a Professor of Earth and Planetary Sciences at Stanford University and, by courtesy, of Earth System Science. He holds a Ph.D. from Harvard University in Organismic & Evolutionary Biology, obtained in 2001, and completed his undergraduate studies at the California Institute of Technology, earning B.S. degrees in Literature and Biology in 1995. His academic and research focus is within the fields of Earth and Planetary Sciences, contributing to the understanding of Earth's processes and systems. As a faculty member, he is involved in teaching, research, and departmental activities at Stanford University, located in Stanford, California.

Research topics

• Computer Science
• Physics
• Engineering
• Astronomy
• Astrophysics
• Systems engineering
• Optics
• Quantum mechanics
• Aerospace engineering

Selected publications

• Structural and physiological constraints on arborescent lycopsid establishment and growth

  New Phytologist · 2025-11-21 · 1 citations

  articleOpen accessSenior author

  The absence of fossil documentation of arborescent lycopsid life-history stages between preserved embryos and mature trees requires interpolation of establishment and juvenile growth. Here, a fossil specimen preserving both proximal and distal vascular anatomy of a single lycopsid tree was studied to compare proximal and distal trunk hydraulic conductivity. Proximal hydraulic conductivity was less than half that of the distal trunk, suggesting the proximal stem could not have been the conduit connecting the mature rooting system and distal shoot. Adding this constraint to other emerging evidence, we demonstrate that existing ontogenetic models could not have applied to arborescent lycopsid ontogeny. We propose a new model that, despite its unusual nature, agrees with all available evidence: sequentially larger stigmarian rooting axes must have been serially produced as the unipolar plant body grew upward and expanded its primary body during early ontogeny, thereby bypassing the proximal shoot. Previous ideas regarding arborescent lycopsid growth relied on highly unusual physiologies and uniquely high growth rates that would then imply extreme geobiological impact on the Earth system. The growth model advanced here accounts for their unique anatomy with much more typical plant biology.

  PublisherOA PDFDOI

• Climbing habit confirmed in the early Permian zygopterid fern Nemejcopteris haiwangii and its palaeoecological significance

  Palaeogeography Palaeoclimatology Palaeoecology · 2025-06-19 · 2 citations

  article
  PublisherDOI

• The <i>Geosiphon–Nostoc</i> symbiosis: recent elaboration or remnant of an enduring association?

  Annals of Botany · 2025-03-28 · 1 citations

  articleOpen accessSenior author

  BACKGROUND AND AIMS: Fungal associations with photosynthetic microbes have regularly been invoked as precursors to the evolution of land plants and their mycorrhizal associations. The fungus Geosiphon pyriformis (Glomeromycotina) deviates from its arbuscular mycorrhizal (AM)-forming relatives through the presence of an intracellular symbiosis with Nostoc cyanobacteria and is frequently viewed as the only extant representative of an ancient and formerly widespread association between fungi and cyanobacteria that occupied early terrestrial ecosystems. Here, we add to growing evidence suggesting the Geosiphon-Nostoc-like associations are not ancestral to AM associations and did not occupy landscapes prior to the evolution of land plants. In addition, we discuss the underlying drivers contributing to the origination and persistence of this argument and other ways in which Geosiphon has been misunderstood. METHODS: We inferred time-scaled phylogenies of Glomeromycotina and leveraged ancestral state reconstruction both to evaluate the plausibility of a Geosiphon-like ancestral state while highlighting the additional complexity required to maintain support for a Geosiphon-like ancestral state. KEY RESULTS: Our analyses overwhelmingly recovered the Geosiphon-like state as being derived from AM associations. CONCLUSIONS: Our work illustrates the diverse ways in which Geosiphon has been misunderstood and adds to a growing body of evidence suggesting that the Geosiphon-like ecology is derived from AM-forming ancestors and did not occupy terrestrial ecosystems prior to the evolution of land plants. We conclude by discussing outstanding questions pertaining to the ecology and evolution of Glomeromycotina fungi.

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• Which arthropods have feet and why? Addressing an argument for aquatic fossil scorpions

  Palaeontology · 2025-08-28 · 1 citations

  articleSenior authorCorresponding

  Abstract Scorpions are the first arguably terrestrial animals identifiable in the fossil record, with important implications for arachnid evolution and terrestrial ecosystem development. However, debate persists on whether some fossil scorpions from the Silurian and Devonian were, in fact, aquatic. This study assesses the claim that a digitigrade (‘footless’) posture implies an aquatic habitat for early scorpions by evaluating the distribution of feet among ambulatory arthropods and how their presence correlates with factors including aquatic versus terrestrial habitat as well as body size, number of legs, cuticle mineralization, and time since terrestrialization. The results demonstrate that these variables in isolation are poor predictors of leg posture, but become highly statistically significant in certain combinations. However, with as many lineages diverging from the usual pattern of plantigrady as adhering to it, predictive power is weak. Therefore, all factors influencing plantigrady must be accounted for when discussing its implications in fossil arthropods, and digitigrady alone does not provide compelling support for an aquatic habitat in fossil scorpions. We further argue that other lines of evidence for an aquatic habitat in Palaeozoic scorpions are equivocal and that the weight of phylogenetic and anatomical evidence supports a terrestrial origin for total group Scorpiones.

  PublisherDOI

• Terrestrialization: toward a shared framework for ecosystem evolution

  Paleobiology · 2025-02-01 · 6 citations

  articleOpen access1st authorCorresponding

  Abstract The Paleozoic evolution of a complex terrestrial biota has been among the most important events in Earth history. Here, we synthesize paleontological and neontological information across the different threads of the biota—including microbial life, fungi, animals, and plants—addressing discrepancies between the fossil record and time-calibrated molecular phylogenies. Four fundamental patterns are emphasized: (1) Most terrestrial animal lineages consist of diminutive inhabitants of soil and litter, with the soil fauna exhibiting remarkable continuity between the Paleozoic and present. (2) Faunal evolution tracks the ecological opportunities afforded by the evolution of the land flora. Flora and fauna alike were initially confined to the thin interface between soil and air, but animals explored both flight and burrowing as vascular plant size increased to encompass tree stature and deep rooting. (3) Skewed nutrient ratios of land plants present a fundamental challenge for animals that are accommodated through contrasting size-based dietary strategies. Detritivory and cell-by-cell herbivory are the diets most readily available for primary consumers but impose limits on the largest possible body sizes; only with subsequent evolution of herbivory in insects and then vertebrates could the dramatic increases in size in the Permian and Mesozoic have been achieved. (4) A second pulse of animal terrestrializations is apparent in the Cretaceous and Cenozoic that might be attributed to increased terrestrial productivity associated with angiosperm evolution. However, environmental changes to nutrient availability earlier in the Mesozoic prevent an unambiguous causal attribution, and the pulse may just be an artifact of our modern vantage point.

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• Organic geochemical evidence for life in Archean rocks identified by pyrolysis–GC–MS and supervised machine learning

  Proceedings of the National Academy of Sciences · 2025-11-17 · 3 citations

  articleOpen access

  Throughout Earth's history, organic molecules from both abiogenic and biogenic sources have been buried in sedimentary rocks. Most of these organic molecules have been significantly altered by geologic processes through deep time. Nonetheless, the nature and distribution of those ancient fragmentary organic remains have the potential to reveal diagnostic biomolecular information after billions of years of burial. Here, we analyzed 406 fossil, modern biological, meteoritic, and synthetic samples using pyrolysis gas chromatography and mass spectrometry. We explored these analytical data via supervised machine-learning methods to discriminate samples of biogenic vs. abiogenic origin, plant vs. animal phylogenetic affinity, and photosynthetic vs. nonphotosynthetic physiology. Dividing 272 samples with known phylogenetic affinity and physiology into 9 categories, each further divided into 75% training and 25% testing sets, our random forest models accurately predict pairwise assignments of modern vs. fossil or meteoritic organics (100% correct assignments), fossil plant tissues vs. meteoritic organics (97%), modern vs. fossil plant tissues (98%), and modern plants vs. animal tissues (95%). Pairwise comparisons between fossil biogenic samples vs. abiogenic samples resulted in 93% correct classifications, while analysis of modern and ancient photosynthetic vs. nonphotosynthetic samples also resulted in 93% correct assignments. Our analyses demonstrate that molecular biosignatures can survive in ancient fossils and allow for the identification of organismal origins and traits. Consistent with previous morphological and isotopic inferences, we present evidence for biogenic molecular assemblages in Paleoarchean rocks (3.33 Ga) and for photoautotrophy in Neoarchean rocks (2.52 Ga).

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• Evolutionary implications of stipule occurrence in Permo-Carboniferous wetland forests dominated by Psaroniaceae

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-06-27

  preprintOpen access

  Abstract Stipules are specialized appendages borne at the leaf base with roles as diverse as sheltering of delicate growing tissues from environmental exposure, vegetative propagation and dispersal, and modification into climbing hooks or protective spines. Stipules are widely present in extant vascular plants, but their origins in geological history remain obscure and must have involved convergent evolution more than once, perhaps as early as the late Paleozoic emergence of forested terrestrial ecosystems. Based on extraordinary collections from the early Permian Wuda Tuff Flora, the earliest known stipule structure in the plant kingdom has been identified in marattialean tree ferns Psaroniaceae, the dominant element of Permo-Carboniferous wetland forests. Psaroniaceous stipules are consistent with protection of juvenile fronds and the stem apex as well as retention of a functional role in mature and withered fronds. Furthermore, the continued and perhaps indeterminate growth and the fully laminated stipules invite speculation of a potential role in vegetative propagation following detachment from the parent frond. However, no direct fossil evidence of stipules acting as vegetative propagules is currently available.

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• Earliest evolution of stipules among vascular plants documented in the late Paleozoic stem group of Marattiales

  BMC Biology · 2025-12-08

  articleOpen access

  BACKGROUND: Stipules are specialized appendages borne at the base of a leaf petiole and may perform a variety of functions including sheltering delicate growing tissues from environmental exposure, facilitating vegetative propagation and dispersal, and providing climbing hooks or protective spines. While stipules are widespread in extant angiosperms and a few fern groups, their origins in geological history remain poorly understood. This study critically reconsiders the absence of stipules in the ancestry of Marattiales. RESULTS: Based on extraordinary collections from the early Permian Wuda Tuff Flora, we report, for the first time, aphlebia fossils organically attached to psaroniaceous petioles. The psaroniaceous aphlebiae are homologous to marattiaceous stipules, as evidenced by numerous shared characteristics. Functionally, psaroniaceous stipules appear to shelter juvenile fronds and the stem apex, with a continued role in mature fronds. Furthermore, their continued and potentially indeterminate growth, along with their fully laminated structure, suggests a possible role in vegetative propagation after detachment from the parent frond. However, no direct fossil evidence of stipules acting as vegetative propagules is currently available. CONCLUSIONS: Our discovery provides unprecedented view of stipules in psaroniaceous tree ferns. The discovery of psaroniaceous stipules is significant, as it represents the earliest known stipule in the plant kingdom and underscores their multifunctional roles in plant development.

  PublisherOA PDFDOI

• Linking host plants to damage types in the fossil record of insect herbivory – CORRIGENDUM

  Paleobiology · 2023-05-01

  erratumOpen accessSenior author

  An abstract is not available for this content. As you have access to this content, full HTML content is provided on this page. A PDF of this content is also available in through the ‘Save PDF’ action button.

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• Linking host plants to damage types in the fossil record of insect herbivory

  Paleobiology · 2023-01-09 · 8 citations

  articleOpen accessSenior author

  Abstract Studies of insect herbivory on fossilized leaves tend to focus on a few, relatively simple metrics that are agnostic to the distribution of insect damage types among host plants. More complex metrics that link particular damage types to particular host plants have the potential to address additional ecological questions, but such metrics can be biased by sampling incompleteness due to the difficulty of distinguishing the true absence of a particular interaction from the failure to detect it—a challenge that has been raised in the ecological literature. We evaluate a range of methods for characterizing the relationships between damage types and host plants by performing resampling and subsampling exercises on a variety of datasets. We found that the components of beta diversity provide a more valid, reliable, and interpretable method for comparing component communities than do bipartite network metrics and that the rarefaction of interactions represent a valid, reliable, and interpretable method for comparing compound communities. Both beta diversity and rarefaction of interactions avoid the potential pitfalls of multiple comparisons. Finally, we found that the host specificity of individual damage types is challenging to assess. Whereas bipartite network metrics are sufficiently biased by sampling incompleteness to be inappropriate for fossil herbivory data, alternatives exist that are perfectly suitable for fossil datasets with sufficient sample coverage.

  PublisherOA PDFDOI

Frequent coauthors

• F. S. Porter

  197 shared

• G. V. Brown

  Lawrence Livermore National Laboratory

  159 shared

• Richard L. Kelley

  Goddard Space Flight Center

  155 shared

• C. A. Kilbourne

  Goddard Space Flight Center

  130 shared

• P. Beiersdörfer

  Cheetah Conservation Fund

  115 shared

• S. M. Kahn

  87 shared

• Kazuhisa Mitsuda

  National Astronomical Observatory of Japan

  67 shared

• C. K. Stahle

  59 shared

Labs

• Vice Provost for Student AffairsPI

Education

• Ph.D., Geology

  Stanford University

  1996

• M.S., Geology

  University of California, Berkeley

  1991

• B.S., Geology

  University of California, Berkeley

  1988