I have come across tMRCA and TMRCA, I have also come across expressions like: 'time of tMRCA'. When I enquired about 'time of tMRCA', I was told it meant 'time of the Most Recent Common Ancestor' where the small 't' represents 'the'. This left me confused about what the 't' stands for in the two terms, i.e. TMRCA or tMRCA.