MESOZOIC ERA: THE AGE OF REPTILES 



56l 



flying. The hind limb was much like that of modern birds and had 

 four digits. The vertebrae were biconcave, as in fish and some rep- 

 tiles. The tail was one of the most peculiar features in that it was 

 vertebrated, with a pair of feathers springing from each joint. In 



modern birds, the ^ „ _ „■ 



feathers are arranged . - 



like the sticks of a " .■'.."_„, 



fan. Archaeopteryx '. ~/sj£,~ "'. " ./'-'.'"; r 



was not well adapted 



for flying, as is shown ' %Jj - ~ - I* ; 



by the poorly de- / 0p ;. - V ^ 



veloped breastbone. -JT ; ■'.'■}■ / ~~ -'*. 



With the exception - / , ^^ ." C 



of occasional short MXv t^V , .^ l : ;i-? 



flights, it probably ; ^ $ :: X ..:.-•■: t ;; ? 



soared somewhat as / ' r -y (. -~ . : 



flying squirrels do to- ^*^~ 



day. Birds probably !f r ; r J -/ ■ ■ :{ 



id not have dino- \\ I" ' v ^-7^. J . : ^^^^ 



saurian ancestors, but ; \ ' ; .. ■' '-'^' ■■;-". .'■• .; 



were presumably de- |^ lU 

 rived from a group of 



primitive, dinosaur- 



Fig. 521. — Restoration of Archceopteryx (Jurassic). 

 The long vertebrated tail, clawed wings, and teeth are 

 well shown. (Modified after Hutchinson.) 



like reptiles that were 



capable of running on 



their hind legs. Archaeopteryx is not known to have lived in 



America ; and only a few specimens have been found in Europe, all 



of which are from the Jurassic. 



Hesperornis. — This bird (Fig. 522) was adapted for life in water 

 instead of in air. It was the largest bird of its time, attaining a 

 length of nearly six feet. The jaws were supplied with small teeth 

 which, instead of being set in sockets as in Ichthyornis (p. 562) were 

 in grooves. As in snakes, the jaws were so constructed as to per- 

 mit the bird to swallow large prey. The tail was vertebrated, but was 

 intermediate between Archaeopteryx and modern birds. Hesperornis 

 was perfectly adapted for aquatic life. Wings were wanting, and only 

 a rudimentary bone was left to show that a wing existed in its remote 

 ancestors. The feet were modified in a manner not found in any other 

 bird, living or fossil, being so joined to the leg as to turn edgewise 

 as the foot was brought forward. The resistance of the water was in 



