140 EXTINCT MONSTERS 
only in outline. It was discovered in 1902 in Montana, U.S., by 
the members of an expedition for the American Museum of 
Natural History in Cretaceous rocks below the Laramie beds. 
Previous discoveries were made in 1856, 1866, 1868, 1876, 1892, 
and 1900, <A specimen found in the last-named year was 
described under the name of Dynamosaurus, thus indicating the 
strength of the beast. It seems to have been contemporary with 
the Ceratosauria, to be described later on (p. 184). Allosaurus and 
Laelaps were related forms, The limb-bones in all these forms 
are hollow. 
Another remarkably bird-like form of Dinosaur, also found by 
Professor Osborn at Como Bluffs, is the Ornitholestes, an active 
little creature, which seems to have walked on its hind legs only, 
like a bird. The hind limb is extremely bird-like and resembles 
that of the oldest known bird, Archzopteryx (see p. 213) with 
its back claw. The hand also is very bird-like, the digits being 
armed with strong claws. Its bones are hollow (in fact mere 
shells), another bird-like feature. The present writer was so 
much struck by the resemblance between this skeleton and that 
of Archeopteryx, that he even ventured to suggest that possibly 
this supposed Dinosaur may have been a bird, perhaps the first 
bird that ever existed ! 
It is perhaps hardly necessary to remark that to any one 
thoroughly acquainted with the structures of living animals, a 
tooth, or a series of teeth, will furnish material from which 
important conclusions with regard to the structure and habits of 
an extinct animal may be drawn. So also with regard to some 
other parts, such as limb-bones, but more especially the bones of 
which the back-bone is composed (known as vertebre). Professor 
Owen has said, “If I were restricted to a single specimen on 
which to deduce the nature of an extinct animal, I should choose 
