Some of these animals are reptiles. Others are not. Click on the reptiles without clicking on anything else!
In a strict phylogenetic system of classification (based on genetic similarities) birds can be considered as reptiles. However the Linnaean system groups by physical similarities and considers them as separate. This subject is a still in frequent debate amongst scientists but for the purpose of this quiz, common usage and grouping is used and birds are not a correct answer.
Ditto on the birds. If the crane doesn't count, then neither should the saltwater crocodile. The crocodile is way closer to the crane than it is to anything else on the list, phylogenetically speaking.
It doesn't really matter how close they might be or whether they had similar origins, birds are not reptiles according to the standard system of taxonomic classification which is what this quiz uses. The kingdom animalia includes the phylum chordata (vertebrates) which is divided into five distinct common classes: reptiles, birds, fish, amphibians and mammals.
This isn't accurate. While these are typical ways for us to organize groups of animals by shared traits, the standard system of taxonomic classification nests aves (birds) distinctly within the larger clade reptilia. If birds are not reptiles, then either the only reptiles are crocodilia or the only reptiles are lepidosaurs. It is not possible to create a monophyletic clade that includes both crocodiles and lizards but does not also include birds (and by extension, all dinosaurs).
Fair enough, thanks for that. The quiz is intended to use common groupings by shared traits, as per the Linnaean system of classification so I've added a caveat to clarify.