This data set describes the phylogenetic relationships of the orders
of birds as reported by Sibley and Ahlquist (1990). Sibley and
Ahlquist inferred this phylogeny from an extensive number of DNA/DNA
hybridization experiments. The ``tapestry'' reported by these two
authors (more than 1000 species out of the ca. 9000 extant bird
species) generated a lot of debates.
The present tree is based on the relationships among orders. The
branch lengths were calculated from the values of \(\Delta
T_{50}H\) as found in Sibley and Ahlquist (1990,
fig. 353).