Antediluvian

Under a leaden sky, a sky fraught with threat and portent, they moved.
Their inexorable line threaded beyond the horizon, and still they came
in pairs, two by two, side by side, together,
a rainbow-hued serpentine,
male and female, large and small, furred or feathered, the mean and the mild,
some ponderously, some lightly with a hop, skip, jump, or flutter.
On they came, a seemingly endless progression of blood and bone.
On and on they came, and on… and on,
to be the last of their kind, to be the first.