I plan on building on a published paper (doi:10.1093/gbe/evaf206). This publication reports mitogenome analysis and I will now take a look at nuclear genomic data to further define the yak X clade, an extinct and previously unknown clade sister to all known yak diversity. While dating based on mitogenomes places the split time of this clade with other yaks to around 675 000 years ago, analysis of nuclear data is now required to fully characterize this newly discovered lineage.