Here is a easy way to beat a t-rex on this game. When you first start the level.there will be an intermission sequence showing the t-rex.then as kong you will fight. An easier way to beat it is two press the a and y button and keep hammering it.(you have unlimited health). Also when it tries to bite yuor neck press the x button as fast as you can to break loose.Keep doing this till it falls on the ground . When it falls press x real fast time break its jaw. Congrats,you just beat the t-rex

Also-you can just press the y button and run and press it again till it falls and then finish it.