You say I’m wrong but then you say that birds are descended from dinosaurs? Are you saying that reptiles are not descended from dinosaurs because…they branched off before dinosaurs?
You have a little bit of a misunderstanding about reptiles and dinosaurs. Yes, birds are directly descended from dinosaurs, in fact they are usually thought of as being dinosaurs. “Reptile” is a higher taxa which contains the living subgroups dinosaurs (only surviving representatives are birds), crocodilians, turtles, tuataras, and squamates (snakes and lizards).
And your language - “older”, “same age” - it sounds like you’re saying they lived at the same time.
They do live at the same time and have since the Jurassic, since again “reptiles” is the higher group containing these subgroups. Crocodilians evolved first in the Triassic, then dinosaurs, then turtles in the Jurassic, then lizards in the Jurassic or Cretaceous (if I remember correctly). Which is what I mean by ‘older’. Reptiles as a group are much older than its subgroup ‘dinosaurs’.
To summarize dinosaurs are not the ancestors of the group we call reptiles. Dinosaurs themselves are reptiles and evolved from preexisting reptiles.
And “evolved” at certain times? I think you mean they branched off - they never stopped (or started) evolving
In this case it is correct to speak of them as ‘evolved’. In this case “Evolved” doesn’t imply they stopped evolving it just means that they perceptibly diverged into a separate major lineage.
Edit: Forgot I was going to include this to help you visualize. This is an (obviously) very simplified version of the reptilian evolutionary tree, along with some relatives. I’m not sure how accurate it is as a whole but the part pertaining to reptiles should be accurate. The branch ‘synapsids’ aren’t considered reptiles according to the strictest interpretation as others have mentioned above, and for some reason fish and amphibians are included; everything else is a reptile. For some reason turtles aren’t included…? (it’s the best I could find super quick on google 
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