Darwin Core Chronometric Age Extension

This Task Group will produce a set of chronometric age terms and with them construct an extension to Darwin Core.

task group
Image by Wolfgang Hasselman

Darwin Core Chronometric Age Extension Charter

A Task Group of the Earth Sciences and Paleobiology (ESP) Interest Group


Core Members

  • John Wieczorek
  • Laura Brenskelle
  • Robert Guralnick
  • Kitty Emery
  • Michelle LeFebvre
  • Denné Reed


The Task Group is required in order to produce a new TDWG standard vocabulary. The new vocabulary to be produced by the Task Group is an extension to Darwin Core for chronometric age information. Chronometric age information is not covered by terms in Darwin Core, and is important in paleontology, zooarchaeology, and archaeobotany.

Goals Outputs and Outcomes

  • Formal definitions for chronometric age terms following the Darwin Core model.
  • Specification for a Chronometric Age extension to Darwin Core that can be used as supplementary information in a Darwin Core Archive. Depends on term definitions.
  • Quick Reference Guide to the Chronometric Age extension following the Darwin Core Quick Reference Guide model. Depends on term definitions.
  • All of the above have already been developed and tested with zooarchaeological and paleontological data sets published in an extension via an instance of IPT.
  • Community discussions have suggested the need for uncertainty measures around both minimum and maximum age. We will finalize the term definitions for these and include them in the extension.
  • We will include mappings from the Chronometric Age terms to EFG (http://geocase.eu/efg). This will be done in the same way that mappings between Darwin Core and ABCD is done - with the term attribute abcd_equivalence.


  • Most of the outputs have already been produced and used for the publication of chronometric age data for multiple zooarchaeology and paleontology data sets. We will try to finalize the definitions of the uncertainty terms through continued community discussion to try to achieve a consensus.
  • The outputs will follow the TDWG Standards Documentation Standard (SDS) and will be reviewed as required processes by the TDWG by-laws https://www.tdwg.org/about/process/ for the ratification of standards.

Becoming Involved

  • Interested parties are invited to watch and contribute to the GitHub repository.


  • Presentations (see references) at the annual meetings of TDWG in 2017 and 2018 as well as in the Darwin Core Hour showed the need for terms to capture chronometric age information for non-neontological information spanning recent archaeological to paleontological biodiversity data. Prototypes and testing were done in a collaboration between ZooArchNet and VertNet, resulting datasets published with a functional Chronometric Date extension, and later with a replacement Chronometric Age extension.
  • Review of the Chronometric Age extension was done in the Paleontology Interest Group meetings in 2017 and 2018, and with researchers in the representing the following groups:
  • Neotoma Paleoecology Database (https://www.neotomadb.org/)
  • The Paleobiology Database (https://paleobiodb.org/)
  • Open Context (https://opencontext.org/)
  • Paleo Core (https://paleocore.org/)
  • Strategic Environmental Archaeology Database (https://www.sead.se/)
  • Smithsonian Institution Department of Paleobiology (https://naturalhistory.si.edu/research/paleobiology)
  • Functional Trait Resource for Environmental Studies (https://futreswebsite.netlify.com/)
  • Florida Museum of Natural History, Environmental Archaeology
  • Florida Museum of Natural History, Biodiversity Informatics
  • Florida Museum of Natural History, Florida Archaeology and Bioarchaeology

  • This Task Group was created to do the followup work necessary to make the already developed material into a ratified TDWG standard, the process and standards for which did not exist when the work on the Chronometric Age extension began.


  • The Task Group will produce a set of chronometric age terms and with them construct an extension to Darwin Core.