About

Timothy Bralower is a professor in the Penn State Department of Geosciences. He earned his Ph.D. from the University of California, San Diego, in 1986. His research interests include micropaleontology, paleoceanography, marine geology, and paleobiology. His work focuses on understanding Earth's history through the study of microscopic fossils and oceanic past environments, contributing to the broader knowledge of geosciences and Earth's evolutionary processes.

Research topics

• Geology
• Physics
• Astrobiology
• Earth science
• Biology
• Environmental science
• Astronomy
• Paleontology
• Computer Science
• Chemistry
• Ecology
• Materials science
• Mechanics
• Oceanography
• Seismology
• Nanotechnology
• Astrophysics
• Botany

Selected publications

• New species evolved within a few thousand years of the Chicxulub Impact

  Geology · 2026-01-16

  article

  Abstract The immediate aftermath of the Cretaceous/Paleogene (K/Pg) mass extinction (ca. 66 Ma) in the marine realm was characterized by the initial recovery of productivity and the originations of new species. These major events are recorded in sediments a few centimeters above the K/Pg boundary and are typically dated via planktic foraminiferal biostratigraphy. The first Paleocene planktic foraminifer biozone is Zone P0, defined as the interval between the extinction of Cretaceous species and the first appearance of the new Paleocene taxon Parvularugoglobigerina eugubina. Constraining the age of the top of the global Biochron P0 is crucial for understanding how quickly this initial diversification occurred. However, the long-accepted value, ~30 k.y. after the boundary, is based on the assumption of constant sedimentation rates across the K/Pg boundary. We provide a new calibration for this important biostratigraphic marker using published records of 3He, a proxy for instantaneous sedimentation rates, from six K/Pg boundary sites. We find Biochron P0 durations between 3.5 k.y. and 11.1 k.y., with an average of 6.4 k.y. Taxonomic concepts vary among researchers, but as many as 10 new species of planktic foraminifera have been observed within Zone P0, with many more reported at or just above its top. Based on our new calibration, the first of these new species appeared <2 k.y. after the Chicxulub impact. The ages and order of these first appearances vary slightly from site to site, suggesting biogeographic differences between sites as novel taxa evolved and dispersed.

  PublisherDOI

• Millennial-timescale thermogenic CO2 release preceding the Paleocene-Eocene Thermal Maximum

  Nature Communications · 2025-06-30 · 1 citations

  articleOpen access

  Abstract Geologic records support a short-lived carbon release, known as the pre-onset excursion (POE), shortly before the Paleocene-Eocene Thermal Maximum (PETM; ~ 56 Ma). However, the source and pace of the POE carbon release and its relationship to the PETM remain unresolved. Here we show a high-temporal-resolution stratigraphic record spanning the POE and PETM from the eastern Tethys Ocean that documents the evolution of surface ocean carbon cycle, redox and eutrophication, confirming the global nature of the POE. Biomarkers extracted from the sedimentary record indicate a smaller environmental perturbation during the POE than that during the PETM in the eastern Tethys Ocean. Earth system modeling constrained by observed δ 13 C and pH data indicates that the POE was driven by a largely thermogenic CO 2 source, likely associated with sill intrusions prior to the main eruption phase of the North Atlantic Igneous Province and possibly biogeochemical feedbacks involving the release of biogenic methane.

  PublisherOA PDFDOI

• Destroyer of Micro Worlds: high-resolution forest fire and terrestrial input records across the K-Pg boundary at El Kef

  Abstracts with programs - Geological Society of America · 2025-01-01

  article
  PublisherDOI

• A neritic record of Oceanic Anoxic Event 2 from coastal Utah: new insights into US Western Interior Seaway paleoceanography and foraminiferal paleoecology

  Gulf Coast Section SEPM eBooks · 2025-01-01

  book-chapter
  PublisherDOI

• Calcareous nannofossil assemblages from El Kef (Tunisia) reveal strong bathymetric controls on Northern Hemisphere recovery patterns following the Cretaceous/Paleogene (K/Pg) mass extinction

  2025-10-12

  articleOpen accessSenior author

  The Cretaceous/Paleogene (K/Pg) bolide impact ~66 million years ago caused the near-demise of calcareous nannoplankton (coccolithophores): key primary producers and major contributors to the biological pump that exports organic carbon from the surface ocean to the deep sea. Although their mass extinction likely had a profound impact on ecosystem structure and function, the interpretation of early Danian recovery patterns remains challenging due to global heterogeneity in both nannoplankton community dynamics and carbon-cycling responses. To explore this further, we generated a ~3.65 Myr nannofossil record from sediment cores recovered near the classic El Kef (Tunisia) K/Pg boundary section, representing an outer continental shelf/upper slope setting in the peri-Tethys Ocean. Our data revealed four distinct nannoplankton acmes, with transitions between them likely influenced by the progressive restoration of biological pump efficiency. Comparison with previously published datasets from multiple ocean basins and paleoenvironmental settings indicates that the sequence of taxa comprising Northern Hemisphere acme successions were predominantly controlled by paleobathymetry at both a regional and global scale. We speculate that these bathymetric controls on nannoplankton acme characteristics were intrinsically linked to global heterogeneity in the restoration of biological pump efficiency. In particular, nannoplankton acmes marked by extremely small average cell volumes persisted for more than two million years at continental shelf sites, whereas contemporaneous open-ocean sites were dominated by taxa with average cell volumes an order of magnitude larger. Because coccolith calcite enhances organic matter ballasting, we suggest that biological pump efficiency was restored faster in open-ocean settings than in continental shelf environments.

  PublisherOA PDFDOI

• Investigating assessment types in an online climate change class: moderating and mediating effects

  Educational Technology Research and Development · 2024-06-21 · 3 citations

  articleSenior author
  PublisherDOI

• Paleogene Earth perturbations in the US Atlantic Coastal Plain (PEP-US): coring transects of hyperthermals to understand past carbon injections and ecosystem responses

  Scientific Drilling · 2024-04-02 · 4 citations

  articleOpen accessCorresponding

  Abstract. The release of over 4500 Gt (gigatonnes) of carbon at the Paleocene–Eocene boundary provides the closest geological analog to modern anthropogenic CO2 emissions. The cause(s) of and responses to the resulting Paleocene–Eocene Thermal Maximum (PETM) and attendant carbon isotopic excursion (CIE) remain enigmatic and intriguing despite over 30 years of intense study. CIE records from the deep sea are generally thin due to its short duration and slow sedimentation rates, and they are truncated due to corrosive bottom waters dissolving carbonate sediments. In contrast, PETM coastal plain sections along the US mid-Atlantic margin are thick, generally having an expanded record of the CIE. Drilling here presents an opportunity to study the PETM onset to a level of detail that could transform our understanding of this important event. Previous drilling in this region provided important insights, but existing cores are either depleted or contain stratigraphic gaps. New core material is needed for well-resolved marine climate records. To plan new drilling, members of the international scientific community attended a multi-staged, hybrid scientific drilling workshop in 2022 designed to maximize not only scientifically and demographically diverse participation but also to protect participants' health and safety during the global pandemic and to reduce our carbon footprint. The resulting plan identified 10 sites for drill holes that would penetrate the Cretaceous–Paleogene (K–Pg) boundary, targeting the pre-onset excursion (POE), the CIE onset, the rapidly deposited Marlboro Clay that records a very thick CIE body, and other Eocene hyperthermals. The workshop participants developed several primary scientific objectives related to investigating the nature and the cause(s) of the CIE onset as well as the biotic effects of the PETM on the paleoshelf. Additional objectives focus on the evidence for widespread wildfires and changes in the hydrological cycle, shelf morphology, and sea level during the PETM as well as the desire to study both underlying K–Pg sediments and overlying post-Eocene records of extreme hyperthermal climate events. All objectives address our overarching research question: what was the Earth system response to a rapid carbon cycle perturbation?

  PublisherOA PDFDOI

• ERRATUM: Stratigraphy of the Cretaceous/Paleogene (K/Pg) boundary at the Global Stratotype Section and Point (GSSP) in El Kef, Tunisia: New insights from the El Kef Coring Project

  Geological Society of America Bulletin · 2024-01-25

  erratumSenior author

  “X-ray diffraction (XRD)” rather than “X-ray fluorescence (XRF)” was printed in the captions to Figure 7, Figure 9, and Figure 10. See PDF file for details.

  PublisherDOI

• Paleoceanographic Significance of Calcareous Nannofossil Assemblages in the Tropic Shale of Utah during Oceanic Anoxic Event 2 at the Cenomanian/Turonian Boundary

  Micropaleontology · 2024-05-01 · 3 citations

  articleOpen accessSenior author

  Oceanic Anoxic Event 2 (OAE2) at the Cenomanian/Turonian Boundary (CTB: 93.9Ma) involved the global deposition of organic carbon-rich sediments, a distinctive positive shift in carbon isotope values, and significant species turnover, including changes in calcareous nannofossil assemblages. While it is thought that volcanism triggered organic C-rich sediment deposition during OAE2, it is unclear whether enhanced productivity, increased stratification, of some combination of the two increased organic matter preservation. Calcareous nannofossil assemblages have the potential to qualitatively assess changes in ocean nutrient and temperature conditions to disentangle such ecological dynamics during OAE2. Here we study an expanded section of the Tropic Shale in a drill core in southern Utah near the western margin of the Western Interior Seaway (WIS) to understand how circulation changed during the event and how this may have influenced primary productivity and organic carbon burial. Relative abundance data of well-preserved nannoplankton are complemented with measurements of trace metal, and organic carbon and carbonate concentrations to determine changes in temperature and water column structure, as well as controls on surface water productivity. Detailed statistical analysis helps refine species paleoecologies combined with information from planktic and benthic foraminiferal assemblages and organic biomarkers. Changes in calcareous nannofossil assemblages indicate that near the start of OAE2 the western WIS surface ocean actually cooled for a short time. Following this, surface waters became warmer and more stratified as a Tethyan water mass invaded the seaway. Assemblages suggest that warmth persisted for much of the OAE2 interval, while stratification waxed and waned. The local seaway cooled near the end of OAE2 as Boreal water masses streamed along the western margin. Variations, including the decrease in the abundance of Biscutum constans and short-lived peaks in the abundance of Eprolithus spp. are super regional or possibly global in extent. There is no correlation between calcareous nannofossil assemblages and trace metal concentrations, suggesting they were unaffected by volcanism-related nutrient inputs. Assemblages support other data that suggest increased stratification influenced organic carbon burial in the Western Interior Seaway, and possibly elsewhere, during OAE2.

  PublisherOA PDFDOI

• RECALIBRATION OF PLANKTIC FORAMINIFERAL BIOZONE P0 WITH ³He DATA IMPLIES LIGHTNING-FAST SPECIATION AFTER THE K/PG BOUNDARY

  Abstracts with programs - Geological Society of America · 2024-01-01

  article
  PublisherDOI

Recent grants

• Collaborative Research: Chicxulub impact effects and the recovery of life using scientific drilling investigations at ground zero

  NSF · $193k · 2017–2022

• Ocean Acidification: Collaborative Research: The response of calcareous nannoplankton to ocean acidification during the Paleocene-Eocene thermal maximum

  NSF · $747k · 2014–2020

• Collaborative Research; The Dynamics Of Carbon Release And Sequestration: Case Studies Of Two Early Eocene Hyperthermals

  NSF · $474k · 2006–2012

• ELT Collaborative Research: Perturbation of the Marine Food Web and Extinction During the Oceanic Anoxic Event at the Cenomanian/Turonian Boundary

  NSF · $423k · 2013–2020

Frequent coauthors

• James C. Zachos

  University of California, Santa Cruz

  103 shared

• S. P. S. Gulick

  The University of Texas at Austin

  84 shared

• Christopher M. Lowery

  International Ocean Discovery Program

  77 shared

• Mark E. Patzkowsky

  Pennsylvania State University

  75 shared

• Wolfgang Kiessling

  66 shared

• Shijun Jiang

  66 shared

• Sara Marcus

  Fullerton College

  65 shared

• Michael T. Whalen

  University of Alaska Fairbanks

  65 shared