Okay, I will break it down and give you my opinion on all of them.
1. Segno - This looks really good! Got a really colourful dinosaur there!

The only thing is I think there might be a little too many colours that don't all really go well with each other.
2. Ateo - Hmm, he really doesn't really remind me of a plateosaurus when I see him, no offense. Something just seems...off. I can't quite put my finger on it. Also, the colouring makes me need to squint a bit.
3. Kronos - This one I really like! You did a very good job!

My only comment would be the way you drew the base of his tail. It should probably look more, oh how do I explain this, more like an extension of his body rather than another appendage.
4. Another good job here!

There is really nothing I can say other than it's a very good job!

I personally, am not one for big triangular spikes, but I am sure you can make them look good

5. Very good! Lovely colours here! He does look a bit...bulky for a troodon. (In my mind troodon are very slim creatures

) Regardless, it is still a very good drawing!
Okay, all in all, I must say wonderful job! You have good drawings, and I know in the future you will only get better!
