This tooth comes from a full-grown adult Spinosaurus dinosaur. At 4.5 inches in length, it is of a size you will seldom see today in a genuine single tooth. With such a large creature, it is nearly impossible to find teeth in this size range that are not severely damaged and severely worn considering the amount of food a large dinosaur would have had to consume to sustain such massive body mass. Not only is this a massive tooth, it is especially rare to have such a sharp tip!
What is important is that it is ONE SINGLE TOOTH and NOT a typical fake made up of a base of one glued onto the tip or body of another. This is a VERY COMMON trick in today's market so LARGE dinosaur teeth from ANY world source, should always be suspect.
WARNING: A common trick to fake large dinosaur teeth in the market is to attach either a bunch of sand mixed with glue on the end of the tooth's root to exaggerate the length or even worse, fabricate a giant impressive tooth by combining and blending multiple teeth sections together to appear as one massive tooth or to fabricate the bottom portion of the tooth and extend, by a much as DOUBLE OR MORE, the original length of the tooth before work started. The workmanship of a few notorious United States-based fakers is of the finest workmanship and VERY convincing in appearance. There have been European fakers also known to create and sell these large teeth. Don't be fooled when you are shopping for large dinosaur teeth of ANY SPECIES, not just Spinosaurus. These are common practices of both unscrupulous and uninformed dealers. We see these "doctored" large dinosaur teeth offered quite frequently and numerous junk, worthless teeth that have been converted and heavily modified are selling for ridiculously high prices, mostly at shows and on the internet. Ebay is one of the worst places for this where fraud runs rampant and unchecked in the entire rare collectibles field but some fossil show dealers and internet sites have been pawning these "creations" off for years now, as well!