good start.

question - are you using reference images?

The t-rex has a very un-usual shape to it. Its very hard to get it right especially without refs. I was doing a rex (still need to finish) and had a lot of trouble with leg areas as the images I found where not very suitable so a lot of eye balling was invoved.

but keep going mate! also post up a wire frame and ill see if i can help you more