Miyashita T, Tanke DH, Currie PJ. 2010. Variation in premaxillary tooth count and a developmental abnormality in a tyrannosaurid dinosaur. Acta Palaeontologica Polonica 55: 635-643. APP is an open access journal, so you can download the article for free!
Tetsuto measures a little Tarbosaurus at the Paleontological Institute in Moscow.
2. Why is it important to consider development when studying fossils?
If you have two different species in front of you and wonder where the differences come from, you will find an answer in development. In other words, a sequence of evolutionary transformations are a history of modifications in developmental processes. Evidence is hard to find -- you can never visualize expression of genes in fossils. You rely on inferences, or simply speculate. But developmental interpretations based on morphology are arguably the most powerful voice in the narrative of evolution, because they explain how a diversity that we see in fossils and living forms was generated.
3. Did this particular individual have enormous teeth?
Yes. The tooth sockets are 25% larger than you expect for a normal tyrannosaurid. The teeth must have been larger accordingly. It is a trade off -- you reduce the number of teeth and create a space to accommodate larger teeth.