96 



GENERAL ORNITHOLOGY 



modifications intermediate in structure between existing Reptilia 

 and Arcs,'' and are therefore inferentially in the direct ancestral 

 line of modern Birds. 



Geologic Succession of Birds. — Birds have been traced back in 

 geologic time to Cretaceous and Jurassic epochs of the Mesozoic or 

 Mid-Life period of the world's history. The earliest ornithichnitcs, — 

 the fossils so called because supposed to indicate the presence of 



Birds by their 

 footprints, Avere 

 discovered about 

 the year 1835 in 

 the Triassic for- 

 mation in Con- 

 necticut. But the 

 creatures which 

 made these tracks 

 are now reason- 

 ably believed to 

 have been all 

 Dinosaurian rep- 

 tiles. The oldest 

 ornitholite, or fos- 

 sil certainly 

 known to be that 

 of a true Bird, is 

 the famous ArcJuv- 

 opteryx, found by 

 Andreas Wagner 

 in 1861 in the 

 Oolitic slate of 

 Solenhofen in 

 Bavaria. This has 

 a long lizard-like 

 tail of twenty ver- 

 tebrae, from each 

 of which springs 

 a well-developed feather on each side ; feathers of tlie wings 

 are also well preserved ; bones of the hand are not fused to- 

 gether, as they are in recent Birds ; and the jaws bear true 

 teeth. This Bird has served as the basis of one of tlie primary divi- 

 sions of the class Aves ; though it has many reptilian characters, it 

 is a true Bird. The great gap between this ancient Avian and 

 latter-day birds has been to some extent bridged by the discovery 

 and restoration of Birds from the Cretaceous formations of North 

 America, such genera as IcUliyornis and Eesperornis forming types of 



Fig. 14. — Oldest known onutholngical treatise, illustrating also 

 the art of lithography in the Jurassic period, engraved by Archwo- 

 pteryx lUhographiai. From the original slab in the British Museum ; 

 after A. Newton, Ency. Brit. 



