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Verbal·Information and Ideas·Reading Closely: Implicit Meanings
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This passage is adapted from Sarah Gibson, “Meet Garganornis: The Giant, Flightless, Weapon-Winged Goose From Ancient Italy.” © 2017 by Sarah Gibson.

When it comes to evolution, islands are weird places.
Species living on islands often experience fascinating changes
in their lifestyle and anatomy. Famously, many small creatures
experience “island gigantism,” as in the case of the huge rats of
Flores, the big lizards of San Esteban, or the massive lemurs of
Madagascar. In recent years, fossil evidence has revealed
another island oddity: the giant goose of Gargano.

Garganornis ballmanni was an odd duck – literally. It didn’t
fly, possibly spent a lot of its time away from the water, and
had a habit of fighting with its wings. On top of that, it was big,
estimated at up to 23kg (50lbs). For a living comparison, that’s
the size of a greater rhea, South America’s largest extant bird.

Dr. Hanneke Meijer of the University of Bergen, Norway,
has been studying island evolution for a long time. She
explained to me that big predators often cannot make it to
islands, and this is a big deal for island denizens. “There’s a
very strong selection pressure that basically is lifted without
those predators present,” she said. So island animals can evolve
traits that might be detrimental in a more threatening
continental ecosystem.

Which brings us to Gargano. Today, this region is part of the
Italian mainland, but during the late Miocene, around 5–7
million years ago, it consisted of one or more isolated islands.
Fossils from the area tell of an ancient insular fauna, including
many small rodents, a “moon-rat” of unusual size, a five-
horned deer, and of course plenty of birds.

Meijer recounted seeing Garganornis for the first time. “I
remember that one of my colleagues … showed me this really
big tibia fragment,” she told me. “He thought it was a mammal
because it was so big.” She originally identified and named the
big bird in 2013 from just that bone. This year, she and
colleagues have published on new Garganornis fossils,
including more leg pieces as well as wing bones.
The author of Passage 2 suggests that the giant goose may have developed its unique features as a result of
A
a lack of big predators.
B
a threatening ecosystem.
C
competition with similar species.
D
a need to migrate to the mainland.