That the variability of an organism to a certain extent is a constant and certain condition of life we admit, otherwise there would be no distinguishable individuals of a species.
Richard OwenThe combination of such characters, some, as the sacral ones, altogether peculiar among Reptiles, others borrowed, as it were, from groups now distinct from each other, and all manifested by creatures far surpassing in size the largest of existing reptiles, will, it is presumed, be deemed sufficient ground for establishing a distinct tribe or sub-order of Saurian Reptiles, for which I would propose the name of Dinosauria.
Richard OwenThe laws of Coexistence;-the adaptation of structure to function; and to a certain extent the elucidation of natural affinities may be legitimately founded upon the examination of fully developed species;-But to obtain an insight into the laws of development,-the signification or bedeutung, of the parts of an animal body demands a patient examination of the successive stages of their development, in every group of Animals.
Richard Owen