8 
DRAGONS OF THE PRIME. 
Jan., 1892. 
their upper ends join with the lower of the two rows of little 
tarsal or ankle bones. (T 2 .) On the other hand, the upper 
row of tarsals -(T 2 ) joins with the lower end of the tibia to 
give rise to a single bone. ( Tt .) 
Starting, then, with the limb of the crocodile as typical 
of that of the reptiles, we find forms among the Dinosaurs 
leading to the condition of the limb in the embryo bird, and 
so to that in the adult, which, is itself so different from that 
in reptiles. The hind-limb, then, of Dinosaurs is intermediate 
in structure between that of the typical reptiles and that of birds. 
In another respect, too, these bird-like Dinosaurs differ 
from typical reptiles and resemble birds, namely, in the 
structure of the limb-bones ; these contain air spaces, just as 
do the limb-bones of birds, and for the same purpose, also, to 
make them lighter. 
The highest forms of the Dinosaurs, then, were animals 
which were very like birds in many ways, but they differ in 
some important particulars. Thus :— 
(1) .—As far as we know they had no feathers, and could 
not flv. 
i/ 
(2) .—The structure of the fore-limbs was unlike that of 
modern birds: in the latter, the bones which correspond to 
those of the palm of the hand are coalesced into one ; in the 
Dinosaurs, these bones are separate. 
(3) .—Again, modern birds have no teeth in their jaws ; in 
the Dinosaurs, the jaws carry many sharp teeth. 
The two last mentioned differences between Dinosaurs 
and modern birds are bridged over by the structure of the 
celebrated fossil bird Archceopteryx ; in it the palm bones or 
carpals are not united together, but are separate as in the 
former, and corresponding to them are three well developed 
fingers, each of which bears a claw. 
Then, again, Archceopteryx has teeth in its jaws like those 
of Dinosaurs, and, in addition, its tail is very long, like that 
of a lizard, instead of being short as in birds. 
Archceopteryx , then, was a very reptilian bird and certainly 
bridges over the space between the Dinosaurs and the modern 
birds. The resemblances between it and the former naturally 
lead us to suppose that we have before us, in the Dinosaurs, 
animals which represent stages in the evolution of birds from 
reptiles; we can trace, as it seems, the reptile gradually 
giving up the old way of walking on all its four limbs, and 
instead, rising into a semi-erect attitude, and stalking along 
on its hind limbs; we see the bones becoming lighter, and it 
seems as if only feathers were needed to change the most 
bird-like Dinosaur into a form like Archceopteryx. 
