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Concept
Crocodile de Johnston
Résumé
The freshwater crocodile (Crocodylus johnstoni), also known as the Australian freshwater crocodile, Johnstone's crocodile or the freshie, is a species of crocodile endemic to the northern regions of Australia. Unlike their much larger Australian relative, the saltwater crocodile, freshwater crocodiles are not known as man-eaters, although they bite in self-defence, and brief, nonfatal attacks have occurred, apparently the result of mistaken identity.
When Gerard Krefft named the species in 1873, he intended to commemorate the man who first reported it to him, Australian native police officer and amateur naturalist Robert Arthur Johnstone (1843–1905). However, Krefft made an error in writing the name, and for many years, the species has been known as C. johnsoni. Recent studies of Krefft's papers have determined the correct spelling of the name, and much of the literature has been updated to the correct usage, but both versions still exist. According to the rules of the International Code of Zoological Nomenclature, the epithet johnstoni (rather than the original johnsoni) is correct.
The genus Crocodylus likely originated in Africa and radiated outwards towards Southeast Asia and the Americas, although an Australia/Asia origin has also been considered. Phylogenetic evidence supports Crocodylus diverging from its closest recent relative, the extinct Voay of Madagascar, around 25 million years ago, near the Oligocene/Miocene boundary.
Below is a cladogram based on a 2018 tip dating study by Lee & Yates simultaneously using morphological, molecular (DNA sequencing), and stratigraphic (fossil age) data, as revised by the 2021 Hekkala et al. paleogenomics study using DNA extracted from the extinct Voay.
The freshwater crocodile is a relatively small crocodilian. Males can grow to long, while females reach a maximum size of . Males commonly weigh around , with large specimens up to or more, against the female weight of . In areas such as Lake Argyle and Katherine Gorge, a handful of confirmed individuals exist.
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