[T]The first birds appeared during late Jurassic times. [T]These birds are known from

four very good skeletons, two incomplete skeletons, and an isolated feather, all from

the Solnhofen limestone of Bavaria, Germany. [T]This fine-grained rock, which is

Line   extensively quarried for lithographic stone, was evidently deposited in a shallow

(5)     coral lagoon of a tropical sea, and flying vertebrates occasionally fell into the water

and were buried by the fine limy mud, to be preserved with remarkable detail In this

way, the late Jurassic bird skeletons, which have been named Archaeopteryx, were

fossilized. [T]And not only were the bones preserved in these skeletons, but so also

were imprints of the feathers. [T]If the indications of feathers had not been preserved in

(10)    association with Archaeopteryx, it is likely that these fossils would have been

classified among the dinosaurs, for they show numerous theropod characteristics.

[T]Archaeopteryx were animals about the size of a crow, with an archeosaurian type of

skull, a long neck, a compact body balanced on a pair of strong hind limbs, and a

long tail. [T]The forelimbs were enlarged and obviously functioned as wings.

(15)              [T]Modern birds, who are the descendants of these early birds, are highly

organized animals, with a constant body temperature and a very high rate of

metabolism. [T]In addition, they are remarkable for having evolved extraordinarily

complex behavior patterns such as those of nesting and song, and the habit among

many species of making long migrations from one continent to another and back

(20)    each year.

[T]Most birds also have very strong legs, which allows them to run or walk on the

ground as well as to fly in the air. [T]Indeed, some of the waterbirds, such as ducks and

geese, have the distinction of being able to move around proficiently in the water, on

land, and in the air, a range in natural locomotor ability that has never been attained

(25)    by any other vertebrate.