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has softened over the years. Paleontologists now suggest its huge beak was better
suited for large fruits and nuts or for scavenging. Still, an encounter with one of
these birds surely would have inspired at least as much fear in a small mammal as
running into a medium-sized theropod during the Jurassic.
Other birds of the past also echo feelings normally evoked by dinosaurs, or at
least a few of their Mesozoic contemporaries such as pterosaurs. For an example of
the latter, the largest flying bird known from the fossil record is the giant teratorn
(
Argentavis magnificens
) from the Miocene Epoch (about 15 million years ago) of
South America. This bird had an estimated weight of 75 kg (165 lbs) and a wing-
span of 7 m (23 ft). If transplanted into the Mesozoic Era, it would have been big-
ger than most pterosaurs, including
Pteranodon
. On land, terror birds—known by
paleontologists as phorusrhacids—lived in South America and the southern part of
North America from about 60 to only 2 million years ago. These flightless birds
ranged from less than a meter to about 3 m (10 ft) tall, the bigger ones fulfilling
their nicknames as top-niche predators in their ecosystems.
Among these terror birds was the Miocene
Kelenken guillermoi
of Argentina,
whichpossessedthelargestskullofanyknownbird:71cm(28in)long,justsmaller
than that of an
Allosaurus
. Again, think of what it was like to be a little mammal
during the Miocene in Argentina, with
Argentavis
in the sky and
Kelenken
on the
land: not so different than living in the Cretaceous, but with a few big mammalian
predators thrown in for good measure, too.
Other huge birds that preceded humans during the Cenozoic included
Drom-
ornis
and its relatives in Australia. Like the South American
Kelenken
that also
livedduringtheMiocene,
Dromornis
stoodabout3m(10ft)tallbutwasbig-boned
enough to have supported about 500 kg (1,100 lbs) on its frame. Its relatives, dro-
mornithids, thrived in Australia until only about 30,000 years ago, including
Geny-
ornis
, a bird almost as large as
Dromornis
. This means that people who first colon-
ized Australia about 50,000 years ago probably saw, interacted with, and ate these
birds. Scientists still do not agree on whether the extinction of dromornithids was
