SilverWook said:

The original Land of the Lost, which aired the same year, has much better dino FX. And that was a mix of stop motion and "live" puppets.

I'm guessing the Beeb couldn't afford Ray Harryhausen's services? ;)

Yeah the budget for Doctor Who was much lower then even children's shows in the states at the same time.

To give you some idea of just how much lower Doctor Who's budget was then the average American show I will compare the budget of two episodes of Doctor Who to one episode of Star Trek made in the 1960s since they have the same run time. Now remember Star Trek's special effects have been mocked from time to time. Well any way for the same run time Doctor Who had a budget of between five and six thousand pounds converted to dollars that makes just under ten thousand dollars give or take. Star trek had a budget of between one hundred and fifty thousand and one hundred and eighty thousand dollars for a fifty two minute episode. That means that Star Trek had a budget of around fifteen to eighteen times what Doctor Who did.

I know this conversion isn't perfect and that both shows had there own problems to contend with(Such as Star Trek's larger cast and model shots that were needed every week)but I bring it up to demonstrate why some times Doctor Who would come up short in the special effects department. Personally it never bothered me,even as a kid. As long as the actors reacted as if they were seeing monsters and space ships I believed in the monsters and space ships even if they were bits of clay and pieces of old toy. Then again I grew up watching a lot of stuff that had bad special effects and was always more interested in the ideas that made up a story then how it looked on screen so I know I do not represent your average viewer.