Are crocodiles dinosaurs?
Crocodiles are in the news again, for all the wrong reasons.
They are reptiles like lizards, turtles and snakes and they have a very ancient lineage.
Crocodiles belong to the clade Archosaur. A clade is a group of organisms that have a common ancestor. Interestingly, Archosaurs also include dinosaurs and pterosaurs.
The earliest fossil crocodile known, lived more than 300 million years ago and the crocodilians developed alongside the dinosaurs.
Like birds, which are now considered dinosaur descendants, crocodilians survived the K-T extinction, 66 million years ago.
Why aren’t crocodiles considered dinosaurs also?
There are a number of reasons particularly surrounding the Archosaur “family tree” and when crocodiles branched off. For you and I, the answer is fairly simple.
A key aspect of dinosaur morphology, or shape, if you like, is that their hind legs are positioned directly under their body. This is true for birds, for instance, but not for crocodiles.
For this reason, also, pterosaurs, flying reptiles from the time of dinosaurs and prehistoric marine reptiles, such as ichthyosaurs, pliosaurs and plesiosaurs are not dinosaurs.
In recent years, crocodiles have appeared in our news as the culprits in attacks on humans. This shouldn’t surprise us and, in fact, crocodiles are fairly easy to avoid.
Those who’ve been attacked took unnecessary risks either through bravado or ignorance. In Australia, the warnings about estuarine crocodiles are clear and simple.
Where are crocodiles found in Australia?
You can expect crocodiles in any watercourse or basin from Fraser Island, across the northern coastline, to Shark Bay in WA.
Don’t go in or on the water, even in small boats or skis and kayaks. Don’t develop habits such as fishing, cleaning fish or dumping fish or meat scraps in the same place regularly. Crocodiles are smart and they learn.
Crocodiles are quite common in Australian tropical waters and the largest grow to at least 5 metres. You are not going to survive a meeting with an animal that size.
How big are crocodiles?
The largest measured crocodile was Lolong, which was captured and measured at 6.17 metres. Lolong was captured in the Philippines. He was suspected of the deaths of several people in his vicinity.
There have been claims of bigger crocodiles, including Krys. He was shot in 1958 near Normanton in Far North Queensland and was claimed to be 8.64 metres long. The accuracy of this measurement is contested though.
There is a skull in the Paris Museum that is 76cm long. Lolong’s skull was only 70cm.
Returning to prehistoric crocodilians, the largest known was Sarcosuchus imperator which may have grown to 12 metres.
Feature photo: Crocodile in the Northern Territory of Australia, by Jocelyn Watts.