The print version of the story carried the following caption (you'll have to imagine the pictures here, I'm afraid):
Freak show: Some of the creatures on the Edge list – the olm (top), a blind amphibian which hunts using electric pulses; the Chinese giant salamander, a pre-historic creature (left); Darwin's frog (below left); and the Gardiner's Seychelles frog, which is smaller than a fingernail
Disregarding the hyphen, why refer to the giant salamander as prehistoric? The OED says 'prehistoric' is "of or relating to prehistory", 'prehistory' being "the period of time before written records". So this particular species predates writing – which has been with us for around 5,000 years. In evolutionary terms, that's not long at all.
The OED does give a second definition of prehistoric: "very old or out of date (informal)" – as in, 'Wow man, that salamander is prehistoric."
Here's a web version of Metro's Edge story, obviously without all the pictures and the caption above. The Metro site did include a gallery of 'ugly amphibian pictures', but that doesn't appear to be working at the moment. So instead here is a photo of a Chinese giant salamander (he's the one on the right):