Yes, there are problems with using growth rates of modern reptiles as a guide to determine those of dinosaurs. If we look to the modern relatives of the dinosaurs to determine growth patterns, we are again baffled. All these animals also show different types of growth patterns. Reptiles continue to grow as long as they live, though the rate slows with age; this is called indeterminate growth. On the other hand, birds cease growing as they reach adulthood; this is called determinate growth.

Some, if not all, dinosaurs probably had a much different metabolism than modern, cold-blooded reptiles, which would drastically alter the growth rate calculations. Also, the actual growth rate depends on the climate where the dinosaur lived. Animals that live in warmer climates grow faster than those in colder ones.