Non-canonical introns are at least 10(9) years old.
Wu
H J
HJ
Gaubier-Comella
P
P
Delseny
M
M
Grellet
F
F
Van Montagu
M
M
Rouzé
R
R
D000818:Animals; D017360:Arabidopsis / Q000235:genetics*; D019143:Evolution, Molecular; D017343:Genes, Plant; D007438:Introns; D008969:Molecular Sequence Data; D016415:Sequence Alignment