Some species can evolve to be smaller, birds for example, are said to come from dinosaurs.
Said? I thought it’s a fact.
I'm not an expert in everything evolution, so I leave those details to them, but evolution is a fact, humans are getting taller through time, our bodies have also changed over time as well.
Why is it called the theory of evolution?
The Darwinian theory of evolution has not been proven and is more likely held in esteem as a guiding philosophy that promotes and inspires scientific thought rather than proof.
Other lesser ambitious examples of evolution can be seen within a species. There just isn't any evidence of one species changing into another species as Darwin asserted. I am not sure Darwinian theory is a mandate on any evolutionary examples. Scientists reject dogma, even Darwinian dogma. Scientists let the evidence speak for itself. It isn't obligated to meet Darwin's standards. We have more information than Darwin had.
You are using the Darwinian term of evolution. Taz is using the word in a broader sense.