ESSDD Earth System Science Data Discussions ESSDD Earth Syst. Sci. Data Discuss. 1866-3591 Göttingen, Germany 10.5194/essd-2026-17 Paleozoic-Mesozoic Terrestrial Total Organic Carbon and Organic Carbon Isotope Database Tian Yaokai 1 Chu Daoliang 1 Lai Jiankang 1 Shu Xiang 1 Zhang Cidong 1 Cui Fangyu 1 Lou Liangyu 1 Liu Xiaokang 1 Wu Yuyang 2 Liang Qingzhong 3 Li Xinchuan 3 Yao Hong https://orcid.org/0000-0002-0367-9528 3 Song Haijun https://orcid.org/0000-0002-2721-3626 1 State Key Laboratory of Geomicrobiology and Environmental Changes, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China College of Marine Science and Technology, China University of Geosciences, Wuhan 430074, China School of Computer Science, China University of Geosciences, Wuhan 430074, China 09 03 2026 2026 1 17 Copyright: © 2026 Yaokai Tian et al. 2026 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://essd.copernicus.org/preprints/essd-2026-17/ The full text article is available as a PDF file from https://essd.copernicus.org/preprints/essd-2026-17/essd-2026-17.pdf

Studies of the terrestrial carbon cycle commonly rely on geochemical proxies such as total organic carbon (TOC) and the organic carbon isotopic composition (&delta;<sup>13</sup>C<sub>org</sub>). However, terrestrial TOC and &delta;&sup1;&sup3;C<sub>org</sub><sub> </sub>data are widely dispersed across the literature and lack a unified compilation, limiting large‑scale synthesis and cross‑comparison. Here, we present a global, standardized dataset of TOC and &delta;<sup>13</sup>C<sub>org</sub><sub> </sub>measurements derived exclusively from terrestrial sedimentary facies: Paleozoic-Mesozoic Terrestrial Total Organic Carbon and Organic Carbon Isotope Database (PM-TOCI). The dataset compiles 66,587 individual data points (49,016 TOC and 17,571 &delta;<sup>13</sup>C<sub>org</sub>) from 619 publications, spanning the Devonian to Cretaceous (419&ndash;66  Ma). Each entry is accompanied by 34 standardized metadata fields, covering geographic information, stratigraphic age, lithology, and depositional facies, thereby enabling consistent filtering, comparison, and reuse across spatial and temporal scales. This dataset is intended to facilitate future data-driven studies of terrestrial organic carbon accumulation, paleoclimate variability, source-rock assessment, and long-term carbon cycle dynamics, as well as the link between carbon cycle and biotic evolution. The dataset is openly accessible at <a href="https://doi.org/10.5281/zenodo.18163858" target="_blank" rel="noopener">https://doi.org/10.5281/zenodo.18163858</a> (Tian et al., 2026).