Avitaxonomicon is a private website that intends to put together up-to-date scientific information on the systematics of birds. Individual families are treated to genus level, but the
exceedingly speciose perching birds (Passeriformes) are treated to family level only.
The project started in 2016, driven by my fascination for birds (and science). Over the years, I realised that today’s taxonomy is still incomplete, lacking a specification how to assign
categorical ranks to taxa. I consider the application of temporal thresholds the only universal way to delimit categorical ranks, including species rank. A first step towards a possible solution
to the rank-allocation issue is suggested on the page “(Chrono-) Taxonomics”.
Fänger, H (2022), Avitaxonomicon website, https://www.bird-phylogeny.de