AFFINITIES 417 



vergent analogies. The upriglit walk, which has been assumed 

 and improved upon independently by members of l)Oth Theropoda 

 and Orthopoda, has produced the same, or nearly the same 

 modifications in them as in the birds. 



It is easy to show that these features are mere coincidences. 

 The oldest bird known is Archaeojoteryx from the Upper Oolite of 

 Bavaria. Consequently all those Dinosaurs, which are (if the 

 same and of later date, have to l)e excluded from the supposed 

 ancestry, and they happen to be those in which (as in Ceratoscmms, 

 CompsognatJiKs, OrnitJiomimus, Iguanodon) the resemldances are 

 greatest. There remains only Anchisaurus of the Upper Trias, 

 more or less contemporary with the Brontozoum, which left its 

 three-toed footprints {Archaeopteryx has four well-developed toes) 

 with Zanclodon. Moreover, the most bird-like foot is either that 

 of the Theropoda, which, like Anchisaurus and Zanclodon, differ 

 from birds by the formation of the pelvis, or of some of the 

 latest Ornithopoda. What, then, is the good of selecting a 

 number of bird-like features from members of Dinosaurs which 

 we are bound to class in different groups, and which existed, 

 some in the lower, others in the middle, or even in the latest 

 Mesozoic periods ? 



Lastly, the advocates of the Dinosaurian ancestry of ))irds 

 cannot have fully appreciated the enormous differences Ijetween 

 the wing of Archaeopteryx and the fore-limb of any Dinosaur 

 with the most avian resemblances in the hind-limbs. The fore- 

 limbs of these reptiles are modified in a direction diametrically 

 opposed to that from which a bird-like wing could be developed. 

 The skull presents another difticulty,and here again Compsognathus, 

 a contemporary of Ao-chaeo2}teryx, comes perhaps nearest to that of 

 a generalised bird's skull. The ancestors of the birds must have 

 combined the followinu- characters: — Of not later than Mid- 

 Oolitic age, with bifurcated pubic bones, four functional toes, elon- 

 gated metatarsals, complete clavicles, premaxillary teeth, and free, 

 not firmly fixed quadrate bones. But such creatures are not 

 Dinosaurs. 



We divide the enormous number of Dinosaurs according to 

 the formation of tl)e pelvis, that of the hind- limbs, and the 

 dentition, into four orders. 



VOL. VIII 2 E 



