Alectrosaurus is not a very well known tyrannosaurid, although there is a decent amount of the skeleton known. It seems to have been quite rare. It is found in the Gobi, and because it is quite slender, it does not preserve well. There was confusion when it was found originally, due to the fact that it was found with a segnosaur. The two animals were thought to be one. What that gave us was a tyrannosaurid with huge arms. Once this was sorted out, it seems to have just been a primitive tyrannosaurid.
There have been a few findings of Alectrosaurus, but little has been printed about them. If more made it to print (especially in English), it might become one of the better known theropods. One important find is that it had a furcula (wishbone). This is now known to be common for a theropod, but until recently, theropods were not thought to have them. Alectrosaurus was found to have one almost ten years ago, but recently, many theropods have turned up with them.