I obtained some matrix from the Aguja formation, which is late Cretaceous, from Brewster, County, Texas. I have been finding all kinds of good stuff, but will start with the following. The first two pics are from what I believe to be a therapod - maybe Tyranasaurid? There are approx. 5 serrations per mm. The next two are of an unidentified tooth. The last is a group photo of what may be Champsosaurus teeth? The hash marks are 1mm. Any ideas?