(i & ii) Dinosaur bones could be the bones of possible living creatures in the time of very early prophets (Alaihimus Salam). As the height and size of previous nations reached heights of approximately 90 feet, dinosaurs (as refered to by science) were most probably regular sized animals in comparison to the size of the humans then.
Skeletons are probably not found because of the following scientific perspective of decomposition of the body.
The rate of decomposition relies solely on the activity of microorganisms and soil structure. In the case of single or shallow graves (Like nowadays), the process of decomposition is usually more rapid, while in mass graves, where bodies are usually packed very tightly and there is little oxygen to promote growth of organisms and decomposition, the bodies may stay well preserved.
This could be the reason why some [i:19c0bba182]dinosaur[/i:19c0bba182] bones still remain.
Some ‘Ulamaa state that dinosaur bones could be the remains of some animals who drowned in the time of Nooh (Alaihis Salaam). As bones are discovered, they are not in the original places and all structures of dinosaurs are rough estimates of those who discover it and name it. This opinion logically makes sense too.
keep in mind that this is not Fiqh related. These are merely opinions of the ‘Ulamaa who have shed some light on the issue. And Allah (swt) knows best.
(iii & iv) A living thing can be from tiny sea particle to creations the human eye can not see. Allah (swt) has created everything for a reason. Islam does not deny scientific evidence unless it opposes Islamic principles. The Qur’aan also demonstrates a deep intellect in science.
Bacteria could be considered alive as there is nothing unislamic about that. It is still a creation of Allah (swt). However, the life of germs and the life of creatures differ in many ways.
And Allah knows best