Credits & licences
Strata pack 2026.09, built 2026-09-21: 1182 data articles compiled from the sources below, 291 editorial articles written by Stratum, 1051 photographs. Each article footer names its sources; each photograph's caption names its author, source and licence. If you reuse an article's facts, cite the source it names; if you reuse a photograph, follow its licence.
Data sources
| Source | Licence · retrieved · attribution |
|---|---|
| Cleveland Museum of Art Open Access | CC0 · 2026-09-21 The Cleveland Museum of Art, Open Access (CC0) CC0 for the works the museum has released as open access (clevelandart.org/open-access). Only records with share_license_status = CC0 are bundled. |
| Wikimedia Commons | CC-BY-4.0 · 2026-09-21 Images from Wikimedia Commons; author and licence shown per image Per-file licence (PD, CC0, CC BY, CC BY-SA); the reuser must credit the author and licence per file (Commons:Licensing). Only CC0, CC BY and PD files are bundled. |
| Macrostrat | CC-BY-4.0 · 2026-09-16 Data from Macrostrat (CC BY 4.0), retrieved 2026-09-16 "All data are provided under a Creative Commons Attribution 4.0 International license (CC-BY-4.0)." (macrostrat.org) |
| The Metropolitan Museum of Art Open Access | CC0 · 2026-09-21 The Metropolitan Museum of Art, Open Access (CC0) "Images of public-domain artworks and basic data on all accessioned works ... available for unrestricted use under Creative Commons Zero (CC0)" (The Met Open Access). Only records with isPublicDomain = true are bundled. |
| Natural History Museum (London) Data Portal | CC-BY-4.0 · 2026-09-18 Natural History Museum, London, Data Portal (CC BY 4.0) © The Trustees of the Natural History Museum, London; retrieved 2026-09-18 Specimen images CC BY 4.0 "© The Trustees of the Natural History Museum, London"; dataset metadata CC0. The Museum cannot warrant the accuracy of the data and use must not imply endorsement. |
| Paleobiology Database | CC-BY-4.0 · 2026-09-16 Data from the Paleobiology Database (CC BY 4.0), retrieved 2026-09-16 CC BY 4.0 — "All records are made available to the public based on a Creative Commons license that requires attribution before use" (PBDB, December 2013). |
| PeriodO — Periods, Organized | CC0 · 2026-09-21 Period definitions from PeriodO (CC0), retrieved 2026-09-21 The PeriodO dataset is published under CC0 (perio.do; LOD Cloud listing). Each period definition cites the scholarly source it was taken from. |
| Smithsonian Open Access | CC0 · 2026-09-21 Smithsonian Institution, Open Access (CC0) CC0 — "for commercial purposes without any attribution, permission, or fee" (Smithsonian Open Access FAQ). Only records flagged CC0 are bundled. |
| Stratum editorial | Stratum editorial · 2026-09-21 Stratum editorial Text written by the Stratum editors; © Stratum. Facts cite the sources listed on each article. |
| Wikidata | CC0 · 2026-09-21 Identifiers from Wikidata (CC0), retrieved 2026-09-21 "All structured data in the main, property and lexeme namespaces is made available under the Creative Commons CC0 License" (Wikidata:Licensing). |
| WoRMS / MolluscaBase | CC-BY-4.0 · 2026-09-16 WoRMS Editorial Board (2026). World Register of Marine Species. Available from https://www.marinespecies.org at VLIZ. Accessed 2026-09-16 Creative Commons Attribution License (CC BY). Required citation: WoRMS Editorial Board (2026). World Register of Marine Species. Available from https://www.marinespecies.org at VLIZ. MolluscaBase: MolluscaBase eds. (2026). MolluscaBase. Accessed at https://www.molluscabase.org. |
| Stratum editorial | Stratum editorial · 2026-09-21 Stratum editorial Written by Stratum in our own words; © Stratum. Sources cited per article. |
Photograph licences
| CC0 | 230 photographs |
|---|---|
| CC-BY-4.0 | 214 photographs |
| CC-BY-SA-3.0 | 167 photographs |
| CC-BY-SA-4.0 | 167 photographs |
| US-PD | 144 photographs |
| CC-BY-2.0 | 50 photographs |
| CC-BY-SA-2.0 | 37 photographs |
| CC-BY-3.0 | 25 photographs |
| CC-BY-SA-2.5 | 9 photographs |
| CC-BY-2.5 | 8 photographs |
CC BY-SA photographs are displayed unmodified apart from resizing, each with author, source and licence in its caption. Nothing from the sources above is altered in substance; boundary ages, classifications and formulas are reproduced as published.
Linked to, not reproduced
| Mindat (Hudson Institute of Mineralogy) | CC BY-NC-SA — not reproduced; mineral articles link out |
|---|---|
| CITES Species+ | No commercial redistribution — a hand-curated list of trade-relevant taxa cites the Appendices instead |
| AAPS Code of Ethics | Reproduction prohibited without permission — paraphrased and linked |
| Canadian Conservation Institute | Crown copyright — conservation science rewritten in our own words and cited |
| American Museum of Natural History — fossil preparation | © AMNH — cited, not reproduced |
| International Commission on Stratigraphy — chart | © ICS — boundary ages taken from Macrostrat/PBDB (CC BY); the chart graphic is not reproduced, ours is drawn from the data |
Warranty
The Natural History Museum, London, requires reusers to note that the Museum cannot warrant the accuracy of its data; the same is true of every source here and of Stratum's own text. Strata is a reference, not an appraisal, a legal opinion or an identification. Collecting rules change; each law article carries the date it was checked and, where a rule could not be confirmed against a primary source, says so.