In my personal opinion, people naturally connect the presence of a dinosaur to prehistoric times. It's what kept me from putting anything like that in my stories. It just... conflicts with the story in rather... annoying ways. However, I managed to get away with my dragons looking dinosaur-like.
I have giant fish in my story world... does that count?
I personally think that prehistoric and fantasy are two different genres that must be handled carefully to bring together. Si-fi and normal fantasy are divided into their separate categories for this reason. I'm sure it's possible! It just... Doesn't click for me. I find it hard to visualize a scientist and an elf together.
However, my friends once worked on this RPG about scientists and other military people traveling to Illudia, a planet frolicking with dragons, elves, blue plants, and other mysteries. It's proof that these two contradicting subjects can be co-used in a story. Allow me to give an expert as an example...
(Oh by the way... The words in the [ ] is dragon speak.)
Seabird wrote:
Meri: Bored beyond boredom. She paws a bush beneath her claws, frightening a little family of pekingsee drakions. She mutters a quick apology and ventures farther away from her mother’s den in the clearing behind her. Deciding that since her father was out with Rodney, and her mother was up in some tree, she could sneak out. hee hee
Morgan: *He wakes up, the mourning light bouncing off his last piece of useful armor, a breastplate made of the finest and lightest metals found on earth. His wife.... *(No... I mustn't think of her...) *Despite his best efforts he couldn’t shake off the memory of their last moments together... How she caressed his chest with her paled and frail fingers before- Out of nowhere a hot-red lizard with leathery, fuzz covered wings lands silently on the polished floor. He ducks his head and scurries under Grawn’s dragon sized table, complete with table cloth to conceal him of course.*
Meri: Once at the spectrum lady’s cave, Meri tentatively pokes her head in. Psshhh mother’s kidding. There’s no on here. But she sees a shuffle in the far corner of the dark den. Its not the spectrum lady, too small. She blinks her eyes, trying to see better. The copper lids echo lightly through the cave. Another couple more seconds and she decided she was mistaken. Quickly she scurries back into the safe outdoors
and hides behind a large blue fern that does little to hide her.
Morgan: *The feathered devil creature flew off just as quickly as it came, fluttering away in a playful way, spinning in the air and dancing with wings stretched out. Morgan crept out of his fortress of cloth and wood. He scratched his head, wondering what the heck that was. It sounded like it had said something in the dragon language but Morgan couldn’t make much sense of it. His brain was still adapting to the native speak. The threat was gone so he took to asking Grawn what the bird thing was. But... Grawn wasn’t in the cave. A stiff breeze blew in and a large sheet of paper-like material landed at his feet. Symbols of sorts covered it. It was a note. Even his translator couldn’t make it out.* (It’s probably about why she left. Oh well! I’m about to do that myself.) *He grabbed a fur from his bed along with some dried food from a ceramic pot that tasted like fish. His wound no longer hurt so he didn’t bother putting on any ointment. He stashed his food in a well sized bag he salvaged from the back of the cave. He then proceeded to continue his journey of running... Running from what he caused.*
Meri: Cocks her head at the odd creature leaving the cave. She had seen two-leggers before, basilisks who walk in their odd way, waddling like birds, legs stuck out as if attached to a stiff stick, and two other appendages hanging uselessly. But this two-legger walked differently, as if his legs were as efficient as dragon’s, with joints, but still his forelegs hanged pointlessly at his side. How does he balance? Meri murmured to herself. He seemed safe, though, and Meri was debating whether or not to leave her scant shelter when her pekingsee friends flew out at the two-legger, twittering in circles a good 2 feet from his head.
Morgan: *He needed to get to a place that wasn’t effected by the war... He wanted to forget all about it. He just wanted things to go back to the way they were. He tromped through the undergrowth in a fashion in order to scare off any bad-hearing creatures and alert them of his presence. It was a technique used in order to avoid startling a bear, but he hadn’t seen any bears. Anyway, there wasn’t any harm of doing it, as long as he kept a weary eye for any good-hearing dragons and the other beasts that roamed the area. The flying creatures that flew out of some undergrowth startled him. They approched him in a curious but wary manner. He was well annoyed by their presense. He began to wave his arms around in an attempt to scare them off. He also progressivly moved away from them in order to just get away from the nunsince. In doing this, he didn’t see the root in front of him and tripped over it. He landed with a grunt into the dirt. The flying creatures flew above, not sure what do next. Morgan rose to his knees and spat dirt out of his mouth and cursed at his luck while sighing angerly.*
Meri: The poor creature was fleeing her flying friends, flapping his useless appendages over his head. When he tripped, Meri shook her head at his foolishness. She crossed the distance between them in two less-than-graceful flying leaps, and, turning her head to the side to see him better, opened her copper eye wide with a click, revealing bright purple eyes. Are you alright, she crooned softly, as she would to any little creature. Seven years old and nearly six feet long, she was hardly much bigger than the creature, but it was hard not to pity the broken one in front of her. And besides, she thought haughtily, she was only a few years from dying. Then she’d be much bigger than she was now.
Morgan: *He continues to growl at his luck with unsavory words and then glances up at the sky to relax himself. But instead of seeing a blue sky dotted with fluffy clouds, he sees a large red bird with bright purple eyes!* {Waahhh!} *He fell onto his back, startled. The lizard-bird spoke softly to him.* At least the language is becoming easier to dissect! Wait... This bird speaks the same language as Grawn! Is she some sort of dragon? Nah... *He decides to talk back, wondering all the while if the red... bird might decide to make him breakfast or not.* {I’m... fine. Uh... You’re not going to eat me, right?} *The language felt strange on his tounge, making rolling sounds and clicks that felt odd, but were speakable through the human mouth. The birds that were pestering him flew over to the bird, like she was some sort or shield. The voice was fememine so he assumed it was female... There wasn’t any way to tell the gender, not with this creature.*
Meri: He speaks! Meri stepped back cautiously. Whipping her tail uncertaintly, she said, [ You have a terrible accent] The birds that were pecking him flew to her. [shhhh, its ok], calming them down. [who are you? … do you know the spectrum lady? my mother says she’ll lock me up in a swamp bubble if she finds me in her cave!! Did the spectrum lady lock you up in a bubble? Rodney, he was in one once. He says they’re really smelly. You’re really smelly.......but then again Rodney’s always smelly, cause he’s a boy. Are you a boy?]
Good luck solving the dinogan (dinosaur-dragon) paradox!
And dinosaurs are something I've always wanted to use, too. 
) and becoming good friends with their charge when it's a boy. They also are spies and scouts during times of war, they are extremely sly and good at talking themselves out of trouble (which will hopefully be somewhat humorous to hear!).
Great stuff!
They will give their own lives to protect their charge, when they develop a close friendship with a child, they may also provide moral support and even encouragement to go in God's direction (so yes they are able to talk, and are very intelligent in their own way). 
