It might sound stupid to say, but rexes are the smallest threat you will face. "But how is that?!" you might ask. "It's a giant tanky eating machine that can get 70+ kills and never die once! D:" Well, I'll tell you.

Rex Attacks
Chomp: The rex eats you whole. It has a somewhat impressive range and can catch you offguard. Stay away from the mouth and you should be fine. Netting the rex temporarily takes away the rex's ability to bite. (NOTE: when a rex eats you they regain health. DO NOT GET EATEN AT ALL COSTS. When you are eaten you have just undone most if not all of the damage you and your friends have done to the rex.)
Stomp: A rex can step on you just as easily as chomp on you. This area of effect passive attack will get you if you're not careful. Give the rex's feet a wide birth to avoid this.

Size Isn't a Good Thing
Rexes are the only dinosaurs that can't go inside buildings. Along with that they get stuck on the terrain very often. Use this to your advantage! If the ground starts shaking get to a rex proof spot as fast as you can. if you are in one of these spots you can easily stay out of the reach of their feet and mouth chomp.

Don't Get Cocky
When the rex can't touch you you might be tempted to turn around and unload into it. However, usually it's just a waste of ammo as the rex has no shortage of health. DO NOT follow the rex when it turns around to walk away. Particularly sneaky rexes can hide around the corner and nom you when you do this. When I play rex most of my kills are from eating people who got too cocky and tried to persue me.

Not A Threat
When you are out of reach of a rex don't pay any attention to it. It can't hurt you while you're in there. However, a carno or raptor can. If you waste all of your ammo in vain trying to kill a rex you will either be reloading or out of ammo when a dino that can get to you comes around. This is easily avoided by paying attention to your surroundings and ignoring the rex.

Don't Prevoke It
If you see a rex in the distance don't take potshots at it. It's really just a waste of ammo and can draw the rex's attention to you. I can't tell you how many times I have played rex and just walked around passively waiting for someone to give away their position so that I can go and eat them.

Raptor Attacks
Pounce: The raptor lunges foward and pins you to the ground. Quickly gnawing your face off. Extremely fast and hard to avoid. Try to stay at a seperate height than the raptor. It will be harder for them to pounce you that way. Only way out of a pounce is if the raptor runs out of stamina or a friend does any damage whatsoever to the raptor.
Claws: The raptor can claw at you doing a decent amount of damage. It only takes 4 swipes of the claws to kill you at full health. netting, shooting or chainsawing the raptor will either kill it or make it run off.

It's Dangerous To Go Alone
Raptors are ambush predators. If you are alone they WILL pounce you and you WILL die because there is no one to save you. As soon as you spawn find your way to other humans. When a raptor pounces you the raptor makes a loud screech noise and your character screams. This tips off friends that a raptor is pouncing you.

Be Aware
Listen to the noises around you. A screech and a scream can tell you of a teammate in need while a hissing roar tells you that a raptor is about to attack. The raptors roar makes it attack ludicrously fast with its claws but drains its stamina. These guys can completely destroy you unless you A: net them, B: shoot them with a hight damage weapon like a shotgun, or C: chainsaw the raptor to death.

Opportunistic
Raptors will stalk you and wait for the opportune moment to kill you. BE AWARE OF SURROUNDINGS. More than once I have been tipped off to the presence of a raptor by its shadow or footsteps. If you spend all of your time trying to shoot a rex that can't reach you you might find yourself in the jaws of a raptor.

Dilo Attacks
Bite: Very weak bite attack that does little damage but does poison you. The poison does damage over time and makes your screen go wobbly. DO NOT PANIC. That's what it wants. If it is in close range get out of any foliage and shoot it.
Spit: The dilophosaurus has the only ranged attack of all of the dinosaurs. This spit attack requires the dilo to roar before use. It has 2 spits until it has to recharge. The spit can damage you with splash damage and blind you with a direct hit. If it is sniping you try to step out of the way of the obvious slow flying line of black goop.

Stealthy Creature
Due to it's small size and some great skins the dilo can hide with ease. It can strike from foliage and due to its low profile fit in small spaces. Due to their low health a few hits with anything will end them.

Spit
The dilo's spit attack can be very annoying and cause havoc among a group of people. Try to avoid the spit or find the dilo and kill it. However, chasing down a dilo might not turn out well if it decides to run off then spit in your face and keep running.

Confusion
The dilo's goal is to confuse you, make you vulnerable so other dinos can take you out. Deny them this by not freaking out and staying aware of more dangerous dinos

Carnotaur Attacks
Bite: A relatively powerful bite attack. Will heal carno if it has roared recently. Will kill you in a few hits. Avoid by walking in circles around the carno, taking advantage of its ridiculous turning circle
Ram: The carnotaur rams into you doing huge damage. Can take out varying amounts of health depending on the speed of the carnotaur. Avoid by strafing when the carno charges.
Head Swing: The carno swings its head at a 90 degree angle doing good amounts of damage. usually used when you walk circles around them. Avoid by staying out of reach of its head.

Hit and Run
Carnos are hit and run predators. They run in, do some damage, and run off to get any lost health back and repeat this cycle. Can wear down a group of people over time. Stop this by doing overwhelming amounts of damage when it comes around or dodging the charge.

Not That Strong
Carnos only have 1000 health and can easily be killed by every human single handedly. Pyro's chainsaw for example, can tear through a carno in seconds.

Turning Turning Turning
Carnos have ridiculously huge turning circles. They can become powerless to fight you if you circle them correctly.

pterasaur Attacks
Bite: A weak bite attack. If it's doing fly-by bites shoot it as it lines up the shot. If the ptera is on the ground then just shoot it. Pteras have very little health and terrible mobility on land.
Grab: Why kill you conventionally when gravity can do the work? The ptera picks you up and drops you from extreme heights. Once picked up you can only hope a friend shoots the ptera before it gets too high or that it runs out of stamina at low altitude.

Take Cover
Pteras usually can only operate in open spaces. Being indoors and staying next to walls can help prevent them from spotting and grabbing you.

Gotta Go Fast
Pteras are the fastest dinosaurs in the game. They can get to max speed, grab you, and take you half-way across the map before your friends even know what happened.

Glass Cannon
Pteras can be deadly but they need to carefully line up their grabs. You can easily kill most pteras on their approach with nets and flames.