Although the analysis of lines of arrested growth (LAG) rings in dinosaur bones has yielded some estimates of growth rates, the technique is not without its problems. It is not known if LAGs truly form in one year. For example, one hadrosaur fossil supposedly had a different number of growth rings in its legs versus its arms. Secondly, growth rates could be size-dependent; in other words, a larger dinosaur might grow slower than a smaller one, just like elephants grow more slowly than mice. Thirdly, some animals may have had indeterminate growth rates like crocodiles. Finally, different species may have different metabolisms, especially when one compares warm-and cold-blooded creatures.