How did Buddha Explain the Creation Of the World?
Which explanation is true? Buddha's or Scientists'? Did Buddha lie When explaining the creation of the world...
  


No enlightened being lies for any purpose. Scientific knowledge is based on hypothesis. The Dhamma is what the Buddha understood through direct knowledge.


  
  It is said that the humans evolved from monkeys. It's evident that
  Dinosaurs lived on earth before humans.
  


In Buddhism, humans are not identified as animals. They devolved from self-luminous gods(brahmas). Not monkeys! Agganna sutta is about how human beings came to dwell on Earth. It doesn't mention about the origin of the animals.

In any case, dinosaur bones being older than human bones doesn't prove that humans came later. 


  " they dwell, mind-made, feeding on delight, self-luminous, moving
  through the air, glorious — and they stay like that for a very long
  time." -Agganna Sutta


A being with such a form cannot be expected to leave any bones behind when they die. It's only much much later their bodies started to harden. 

According to Science, dinosaurs lived between 230 and 65 million years ago. Land plants had evolved on Earth by about 700 million years ago and land fungi by about 1,300 million years ago. According to Agganna sutta, the earth didn't even have trees when the first humans came. 

We were here even before the first mushrooms(fungi) appeared on earth:


  Then, mushroom-like plants began to grow so fast that they replaced
  the mud-like ocean. The creatures began to devour them as well, and
  they also found it delicious, like sweet honey and milk. Their body
  hardened more and details began to turn finer. -Agganna Sutta