What is "transitional"

Usage examples of "transitional".

So that we might obtain the parent-species and its several modified descendants from the lower and upper beds of a formation, and unless we obtained numerous transitional gradations, we should not recognise their relationship, and should consequently be compelled to rank them all as distinct species.

The two states of reality overlapped in these transitional stages, and the criterion I used to differentiate the latter from either state of reality was that their component elements were blurred.

A few of the unconscious aliens were obviously genetically unaltered, since they had entered the transitional or lepi-dodermoid phase of their allomorphic cycle.

Thus in lower Egypt the transitional Amratian culture -- a Neolithic culture that was acquiring the use of metal -- knew of gold from Nubia before 4000 B.

Of course, scientists may point to Archaeopteryx, but it arrived fully formed, showing no fossil record of any transitional forms.

Chapter VI Difficulties on Theory Difficulties on the theory of descent with modification -- Transitions -- Absence or rarity of transitional varieties -- Transitions in habits of life -- Diversified habits in the same species -- Species with habits widely different from those of their allies -- Organs of extreme perfection -- Means of transition -- Cases of difficulty -- Natura non facit saltum -- Organs of small importance -- Organs not in all cases absolutely perfect -- The law of Unity of Type and of the Conditions of Existence embraced by the theory of Natural Selection.

Furthermore, we may conclude that transitional grades between structures fitted for very different habits of life will rarely have been developed at an early period in great numbers and under many subordinate forms.

A couple of years ago I became fascinated by the Aquatic Ape Hypothesis, the notion that our transitional ancestors spent a period in a semiaquatic environment.

If then, there be some degree of truth in these remarks, we have no right to expect to find in our geological formations, an infinite number of those fine transitional forms, which on my theory assuredly have connected all the past and present species of the same group into one long and branching chain of life.

These difficulties and objections may be classed under the following heads:- Firstly, why, if species have descended from other species by insensibly fine gradations, do we not everywhere see innumerable transitional forms?

We should be extremely cautious in concluding that an organ could not have been formed by transitional gradations of some kind.

Although we must be extremely cautious in concluding that any organ could not possibly have been produced by successive transitional gradations, yet, undoubtedly, grave cases of difficulty occur, some of which will be discussed in my future work.

If such gradations were not fully preserved, transitional varieties would merely appear as so many distinct species.

In the cases in which we know of no intermediate or transitional states, we should be very cautious in concluding that none could have existed, for the homologies of many organs and their intermediate states show that wonderful metamorphoses in function are at least possible.

If this had been effected, who would have ever imagined that in an early transitional state they had been inhabitants of the open ocean, and had used their incipient organs of flight exclusively, as far as we know, to escape being devoured by other fish?