Table 4.

Comparison of phylogenetically implied gaps and formation numbers for Triassic archosaurs

SubstageDuration (My)Ghost rangeArchosaur formationsStratigraphic gapsAll-tetrapod formationsStratigraphic gaps
Ind1.5059324
Ole(l)1.503111719
Ole(u)1.5577360
Ans(l)3.58682313
Ans(u)3.51068306
Lad(l)1.5123111026
Lad(u)1.5162121620
Crn(l)3.35101131521
Crn(u)3.57131342
Nor(l)6.511041620
Nor(m)6.511402016
Nor(u)6.511311818
Rht(l)30861620
Rht(u)30311927
Totals46.857194102292212
  • Data are tabulated from a recent cladistic analysis in Brusatte et al. (2010, fig. 8), from which phylogenetically implied gaps (‘Ghost range’) are drawn, and then compared with the inverse of the number of formations, as a measure of absence of information (‘Stratigraphic gaps’=maximum number of formations in a time bin [14] minus actual number). Comparisons are made with the strict FFC (‘Archosaur formations’) and the comprehensive FFC (‘All-tetrapod formations’).

  • Abbreviations of stratigraphic stage names as in Table 1, plus Rht, Rhaetian.