(i) 2 million years ago tree trunks that got buried along the river, incourse of time the organic matter was replaced by silica and was fossilized.
(ii) They retained their colour, shape and texture and was converted into solid rocks.
(iii) The annular rings, the texture, colours of the layers, nodes and every properties of plants are still visible.

Natural selection is a driving force for evolution.
Over production:
(i) Living beings have the ability to reproduce more individuals and form their own progeny. 
(ii) They have the capacity to multiply in a geometrical manner.
(iii) This will increase reproductive potential leading to over production.
Struggle for existence:
(i) Due to over production, a geometric ratio of increase in population occurs.
(ii) The space to live and food available for the organisms remain same
(iii) This creates an intense competition among the organisms for food and space leading to struggle.
The struggle for existence are of three types:
(i) Intraspecific struggle: Competition among the individuals of same species.
(ii) Interspecific struggle: Competition between the organisms of different species living together.
(iii) Environmental struggle: Natural conditions like extreme heat or cold, drought and floods can affect the existence of organisms.
Variations:
(i) The occurrence of variation is a characteristic feature of all plants and animals.
(ii) Small variations are important for evolution.
(iii) According to Darwin favourable variations are useful to the organism and unfavourable variations are harmful or useless to the organism.
Survival of the fittest or Natural selection:
(i) During the struggle for existence, the organisms which can overcome the challenging situation, survive and adapt to the surrounding environment.
(ii) Organisms which are unable to face the challenges, are unfit to survive and disappear.
(iii) The process of selection of organisms with favourable variation is called as natural selection.
Origin of species
(i) According to Darwin, new species originates by the gradual accumulation of favourable variations for a number of generations.

(i) Fossils are remains or impressions of organisms that lived in the remote past.
(ii) Fossil provide the evidence that the present animal have originated from previously existing ones through the process of continuous evolution.

Yes, he is correct.
Reason: The function of the wings of a crow (the wings of a bird) and wings of an insect are similar, but the basic structure is different.