You see, it turns out that scientists have recently split C. novaeguineae into two species - the original, and a new one called Hall's New Guinea Crocodile (Crocodylus halli). This has been done on the basis of skull morphology - Hall's crocodile (named for herpetologist Philip Hall) has a shorter, wider snout. The newly described species hails from the southern portion of the island, while the original species is from the north. The two are separated by the New Guinea highlands. That different species should be isolated like this on an island isn't surprising - take a look at the island's human inhabitants. New Guinea boasts of hundreds of languages and ethnic groups, as its rugged terrain fosters isolation splendidly.
(For what it's worth, based on the picture above, I suspect the animal in the picture is C. halli)
Discoveries like this pose major headaches for zoo breeding programs. There is not a Species Survival Plan in place for New Guinea crocodiles, but imagine if there was - and then than 25%, 50%, who knows how many of your animals of a different species, or that you'd been hybridizing two species for years? In many managed populations, there is an increased emphasis on doing genetic analysis to determine relatedness and genetic variability.
Taxonomy, the science of classifying living things, is in a constant flux between the splitters, who are always breaking species into more species, and lumpers, who disagree with such distinctions. Lately, armed with genetic tools, the lumpers are winning. There were 12 species of crocodile when I was a kid. Now there are, I don't know, 17? 18? It keeps changing. And it's not there are more animals in the world - it's just a question of how we count them.
How we count and classify them, however, influences how we manage and breed them - so it pays to have a little more certainty.
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