LOS ANGELES -- The lowly louse may have a more impressive
pedigree than once thought: Dinosaurs may have hosted the
parasitic bugs, a study says. The findings, published Tuesday in
the journal Biology Letters, also show -- through comparison of
lice -- that mammals and birds may have begun to flourish before
the dinosaurs went extinct 65 million years ago. That's counter
to a long-held idea that they ascended and diversified only once
the dinosaurs were gone. Lice spend their entire lives on one
species, so they evolve along with their hosts. That means their
similarities can be used as a way to study evolutionary
relationships between the creatures they live on. "Some people
have described lice as heirlooms -- they're just inherited --
which is why they tend to track the evolution of their hosts
pretty well," said study coauthor Kevin Johnson, an
ornithologist at the University of Illinois, Champaign. The
international team of researchers looked at DNA differences
between 69 modern lineages of lice that feed