Many Young Earth Creationists (not all) are happy to accept Micro-Evolution; but denounce Macro-Evolution. They make the claim that macro changes within species cannot happen, because as just one example: one never sees a "cat turn into a dog". Creationists often use the word 'kind' ...You don't see one "kind of animal" change into another.
Of course this claim that if Evolution by Natural Selection, was a real phenomena of nature, then macro changes should be directly observable, is not a claim made by scientists, it is a claim made by Young Earth Creationists and Intelligent design advocates.
If we did observe cats changing into dogs, right before our eyes, that would not be proof of Evolution by Natural Selection and more specifically it would not be proof of Macro-Evolution. If this were to ever happen, it would turn the theory of evolution on its head. One would be tempted to call such a physical phenomena, a miracle.
Biologists are not sat in labs waiting for cats to turn into dogs. This is a straw man argument dreamed up by religious quacks.
So, what is Macro-Evolution? - Macro-Evolution relates to time. It is simply multiples of Micro-Evolution over time. In other words, Macro-Evolution is Micro-Evolution writ large. There are not two different phenomena. There are just lots of multiplications of the same process over time. When you add these multiples together, it is convenient to use the word macro.
The fact that Macro-Evolution is just a concept to describe a sum or a totality of micro changes over time, is precisely why you will never see a cat change into a dog. It is also precisely why there is no contradiction between micro and macro evolution.
Though one will never see a cat change into a dog. We do know that given enough time and the right natural conditions within the environment, one species can gradually evolve into another species through the process of Evolution by Natural Selection. There is no contradiction whatsoever in calling that change Macro-Evolution... But a synonym for that same process is: Multiples of micro-changes through time, that lead to dramatic physiological changes.
We know that these Macro changes do take place through identifications within the fossil record... For example:
(Reference Talk Origins: http://www.talkorigins.org/faqs/comdesc/section1.html#morphological_intermediates_ex1)
1) Birds to Reptiles: The finding of a complete set of dinosaur-to-bird transitional fossils with no morphological "gaps" (Sereno 1999), represented by Eoraptor, Herrerasaurus, Ceratosaurus, Allosaurus, Compsognathus, Sinosauropteryx, Protarchaeopteryx, Caudipteryx, Velociraptor, Sinovenator, Beipiaosaurus, Sinornithosaurus, Microraptor, Archaeopteryx, Rahonavis, Confuciusornis, Sinornis, Patagopteryx, Hesperornis, Apsaravis, Ichthyornis, and Columba.
2) Reptiles to Mammals: complete series of fossils for the reptile-mammal intermediates, ranging from the pelycosauria, therapsida, cynodonta, up to primitive mammalia.
3) Human-Apes: Collection of fossil hominids.
4) Legged Fossil Whales: land mammal-to-whale fossil intermediates.
5) Legged Sea Cows: (manatees and dugongs) are fully aquatic mammals with flippers for forelimbs and no hindlimbs.
The above are prime examples and all qualify as Macro-Evolutionary transitional fossils.