This is my original guide published on playstationtrophies.org. Re posting here.

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Overview:

• Estimated trophy difficulty: 2/10
• Offline trophies: 13 (1, 11, 1)
• Online trophies: 0
• Approximate amount of time to Platinum: 30min - 1 hour
• Minimum number of playthroughs: Less Than 1
• Number of missable trophies: None
• Glitched trophies: None
• Does difficulty affect trophies?: No difficulty levels
• Do trophies stack?: Yes, there are 3 PS4 stacks available: NA, EU and Asia.
• Do cheat codes disable trophies?: No cheats available
• Additional peripherals required?: None

Introduction:

Prehistoric Dude is a metroidvania style game developed by LightUp and released on the PS4 by Ratalaika Games. The game intro sees you, a caveman, having his lunch stolen by a dinosaur, and so you set out on a quest to retrieve it. 

The game is very basic, with a short map of screens/zones to explore. Nothing is too hard and with some agreeable music, bright 8-bit graphics and reasonably good level design for how simple it is, the game is overall pretty enjoyable.

Trophy-wise you are looking at a quick and easy platinum, as most of the trophies are related to doing some simple exploration, with the platinum coming by the time you defeat the second boss. No trophies are missable and if the platinum has not unlocked by the time you defeat the second boss, all zones remain accessible and backtracking is available.


Walkthrough:

Set 1: Start a New Game and Play Through to The Second Boss:

Simply start a new game, there is no difficulty select. Under each of the trophy descriptions below you will find instructions on how to find the location you need. The game is not linear, some back tracking is required and there are zones and paths that are not necessary.

For Well invested?, you will need to have 100 pieces of fruit in your possession at the time. As you move through the world and pass the leafy bushes on the ground, fruit will pop out and be available for collection from time to time. The amount of fruit you have is shown on the screen in the top right corner. Every time you die you will restart at the beginning of the particular zone you are in, and you will loose half the fruit you are carrying. If you get to the point in the game where you are required to unlock Well invested? and you don't have 100 fruit it is easy to farm fruit pickups as they respawn every time you leave and revisit a zone.

Full game completion is not required for the platinum. Long neck requires you to defeat the second boss and by this time, if you are following the guide, the platinum is also possible. If you have missed something don't panic, all zones are still accessible and clean up can be achieved during step 2.

Below is a video showing a platinum playthrough.

Video created by the_game_nerd.

At the end of this step, you will have the following trophies:

Looks useful 
I like this 
I Might need this 
Better safe than sorry 
Healthy 
Athletic 
Roasted bird 
Long neck 
Need a keychain? 
Well invested? 
Evolve 
Treasure 

Step 2: Clean up:

If, after the second boss fight with the Supersaurus, you have not unlocked Platinum Dude, then you will have to back track through the zones to collect anything you have missed.

By the end of this step, you will have unlocked the following trophies:

Platinum Dude 

• Platinum Dude

  Get all other trophies.

  You know what you have to do, unlock all other trophies for this shiny platinum

• Looks useful

  Find the Mountaineer Gloves.

   

  The mountaineer gloves give you the ability to cling onto the edges of higher up platforms, allowing you to reach ledges that would be unreachable with just a standard jump.
  
  To find the gloves, from your starting point in the game, move one zone to the right, then one zone down. The gloves can be found in the left hand side of this zone.
  
  To use the gloves, push either  or  (depending on the direction you are jumping) as you jump to a high up ledge.

• I like this

  Find the Club.

   

  You start the game with the ability to throw an axe, though these are not unlimited however and must be collected from the leafy bushes much like the fruit. The Club is a melee weapon, and finding it will unlock this trophy.
  
  To find the club, from the Mountaineer Gloves, return 1 zone up, then 1 zone right, then 1 zone down. The Club can be found on the far right of this zone.

• I Might need this

  Find the Tonic of Fortitude.

   

  The Tonic of Fortitude is your will appear as your reward for defeating the first boss fight with the Ptecsaurus. It must be manually collected and the trophy will unlock as soon as you have it. The tonic allows you to push boulders which will be necessary later on in the game.

• Better safe than sorry

  Find the Bamboo Stick.

   

  The bamboo stick allows you to breath underwater. To find the Bamboo Stick, from the first boss fight area, go 1 zone back left, then 1 zone up. In this zone head to the left to find a locked fence. To open this fence, you must push the grey colored rock on the ledge above the fence off, then onto the button below. For this you need the tonic from I Might need this, and by pressing  while walking into the rock you are able to push it.
  
  Once the rock is on the button, the fence will open and you can go through. In this next zone, go all the way to the left to find 5 switches on floating platforms above some water. Trigger all 5 switches to open another fence on the left, behind which is the bamboo stick. Collect it to unlock this trophy. 

• Healthy

  Get more health.

   

  For this trophy you need to find a health upgrade, this will increase your health by 1 bar. To find this, go 1 zone to the right from where you found the chest for Treasure. A health upgrade can be found in the top right of this zone.
   

• Athletic

  Get more stamina.

   

  For this trophy you need to find a stamina upgrade, this will give you an additional bar to your stamina gauge. To find it, from the silver key location for Need a keychain?, go 1 zone up. In this zone go left along the bottom, jumping over the spike pits until you find the stamina upgrade in the far left of the zone.
   

• Roasted bird

  Defeat the first boss.

   

  To get to the first boss fight, from the location of the 100 fruit fence from Well invested?, head 1 zone left, then 2 zones down. In this zone go to the far right and you will see a blue colored area with a monster face sign and a fence. This fence requires a silver key which, if you have been following this guide, you will already have. If not, see Need a keychain?.
  
  Go through the fence and enter the next area to start the boss fight against the Ptecsaurus, a flying dinosaur much like a pterodactyl. This is pretty easy as far a boss fights go. It will swoop down at you when it is directly above you, so to defeat it stand on the edge of the lava pit and and wait for the bird to fly over the pit, and when it does, jump across to the other side and it will swoop down into the lava. The boss' health bar is in the bottom left of the screen, 6 dunks in the lava pit and the boss is....toast. The trophy will unlock as soon as the boss is dead.
   

• Long neck

  Defeat the second boss.

   

  From the location you found the bamboo stick for Better safe than sorry, you will need to find 2 more silver keys to unlock fences to the second boss.
  
  Key 1: From the bamboo stick location return to the area of the first boss fight, 1 zone right, 1 zone down then another zone right. From the first boss fight area go another zone right and you are now in the caves world. From here go 2 zones up and in this zone you must kill all enemies before flipping the switch in the middle and opening the fence to get the silver key.
  
  Key 2: After finding key 1, return 2 zones down to the first of the cave world zones, then another 2 zones down to a zone with a grey pushable rock at the top of some levels and a silver key locked behind a fence. To open the fence push the grey rock onto the button on the right. Once the fence is open collect the key and return 2 zones up to the first of the cave world zones.
  
  Now that you have 2 silver keys, you are ready to face the second boss. Head to the right of this zone to see the first locked gate which will open as you approach. In the next zone go far right again and open the last fence to the second boss, enter this zone to start the boss fight against the Supersaurus.
  
  This boss fight is a little more complicated that the first, but still pretty simple. I found it easiest to stay on the platforms on the left of screen and as the dinosaur's head appears in random locations either drop down, jump up or turn around and hit it with an axe shot or two before dodging its fire shot. 10 hits and the Supersaurus is dead and this trophy will unlock.

• Need a keychain?

  Find your first silver key.

   

  Immediately after using the lever for Evolve the fence will open and the silver key will be available for collection. Collect it to unlock this trophy.

• Well invested?

  Open a 100 fruits fence.

   

  For this trophy you need to unlock the fence with the 100 X Fruit sign in front of it. To find this fence, from the location you found the stamina upgrade for Athletic, head 1 zone to the right. It can be found in the bottom right corner of this zone.
  
  The fence will automatically open if you are holding 100 pieces of fruit or more in your inventory, but will remain closed if you do not have 100 or more. If you are carrying less than 100, don't despair. Each time you leave and re-enter a zone the random fruit drops respawn, so simply leave the zone, re-enter and collect more fruit. Rinse and repeat this process until you have 100 fruit then return to the fence.

• Evolve

  Use a lever.

   

  From the health upgrade you found for Healthy, go back 1 zone to the left, then 3 zones up. In the top right of this zone you will see a silver key locked behind a fence. Interact with the lever in front of the fence to unlock this trophy.
   

• Treasure

  Open your first chest.

   

  Chests contain bulk fruit and axes. You can find your first chest 1 zone down after picking up the Club, in the top right hand part of this zone.