If you want to clone a dinosaur this way, then you'd need a nucleus from a dinosaur cell. But you'd also probably need a dinosaur egg to transfer it to. Dinosaur genes will create dinosaur proteins which would probably work best in dinosaur cells. Well, maybe they might work in bird cells but that's something we don't know.

Dinosaur cells are really difficult to come across. Even if you do find one, the DNA and any associating proteins would most likely be destroyed through the processes of fossilisation.

Fortunately, or unfortunately (if you like), we cannot clone dinosaurs.  We simply do not have any  DNA to reconstruct the genome of a dinosaur.  Bone marrow and blood, the best parts of an animal to get DNA from don't survive the fossilisation process to provide the complete sequence of DNA required (although some scientists claim to have extracted fragments of DNA fom the long bones (legs) of dinosaurs).

The ideas in Jurassic Park were fun, and made a good story.  However, even if you take 'biting insects' from amber (to look for blood from the last meal they ate, before becoming entombed in tree sap) there are two problems:  Firstly the blood that they are eating is a meal, so it will be (in the process of being) digested, and secondly we don't have any amber with biting insects in as old as the dinosaurs (to the best of our knowledge).

The book  'The Science of "Jurassic Park" and the "Lost World": How to Build a Dinosaur' by Rob DeSalle and David Lindley is a fun read that will highlight all the problems (from the point of view of Jurassic Park at least) in making a dinosaur.  However, one group of dinosaurs is still with us.  The birds are avian (flying) theropod dinosaurs.  They have no teeth like their non-avian (non-flying) relatives but they still have many of the genes required to make them.  These genes have just been switched off.  Developmental biologists have been able to switch them back on, in the embryos of chickens, so that teeth actually start to develop.
So, as the 'Science of Jurassic Park' suggests, maybe the way to get a sort of dinosaur is to reverse engineer a chicken, but we will never be able to bring  T. rex back from the dead.