giga-annum

plural giga-annums

1. Synonym of gigayear: a billion years.

   Possible cyanobacteria from the Apex charts of western Australia, which have been dated at ~3.5 (giga-annums, or billions of years).

   2018, Ronald Martin, Earth’s Evolving Systems: The History of Planet Earth, 2nd edition, →ISBN, page 214

   2 more examples

   Geophysicists today estimate the earth’s age to be 4.5–4.6 Ga (giga-annums = 1 x 10⁹ years) based on data from lead isotopes (Dalrymple 403).

   2000, A. S. Weber, Nineteenth-Century Science: An Anthology, →ISBN, page 387

   We report here the sequencing and genomic analysis of the SDR of Ectocarpus, a brown alga that has been evolving independently from plants, animals, and fungi for over one giga-annum.

   2014, Sophia Ahmed et al., “A Haploid System of Sex Determination in the Brown Alga Ectocarpus sp.”, in Current Biology, volume 24, number 17, →DOI

   Synonyms: gigayear