2. FUTURE TRENDS
3. NO. OF SPECIES?
4. OTHER DEBATES
WANT MORE DETAIL? CHECK OUT KING & BURKE 1997
READ THE DEBATE ABOUT CAIMAN CLASSIFICATION
BACK TO THE
If you thought that classifying crocodiles was easy, think again. There has been a lot of confusion over crocodilian taxonomy for decades, and the debate is still very lively!
Traditionally, the relationships between various species have been described using "Linnean ranks", which places organisms into increasingly specialised groups depending on their apparent shared characteristics. For example, crocodiles are covered in scales, have four legs and a tail, and bask in the sun. This is very similar to a green iguana, and hence both have been classified as reptiles, or more specifically the Class Reptilia. However, crocodiles are clearly physically different to green iguanas in other ways, show different behaviours, and live in totally different ecosystems. To reflect this, green iguanas are placed in the Order Squamata, and crocodiles are placed in the Order Crocodylia.
Taxonomists, however, do not necessarily agree on which species are more closely related to which others, and naming conventions can vary. Revision takes place all the time, which often makes matters more convoluted and leaves interested observers wondering just what to believe. The most recent revision and review of the Linnean system for crocodilians was undertaken by King & Burke (1997) (see link to left if you want to read it), and they classified crocodilians as follows:
Recent discussions in palaeontology have also resulted in the accepted use of another level above families to include extinct forms. This uses the suffix "-oidea" (i.e. Alligatoroidea, Crocodyloidea and Gavialoidea). However, the list of species shown above is perhaps the most widely recognised classification in use today, and is the one adopted by this website. Of course, the story does not end here. Much of the above is now being reappraised through phylogenetic taxonomy, and there are still many debates on areas yet to be adequately resolved with the current system (e.g. whether Tomistoma should be classified with the Crocodylidae or the Gavialidae, which will be discussed here in more detail in a later update).
* NB. King & Burke (1997) actually use the name Crocodylus johnsoni (without a "t") on the basis that it was the original spelling used by Krefft in 1873. However, there is debate over the preferred usage, and johnstoni is widely used (see discussion later).