Pretty ugly. Same difference. Awfully good. Definite possibility. Those are good examples of an ‘oxymoron’ – a figure of speech in which apparently contradictory terms appear in conjunction. Some oxymorons from the animal kingdom are dwarf elephant and jumbo shrimp. It turns out oxymorons have been around for a long time – longer than language itself, in fact. For proof, we present the recent news that the oxymoron existed 15 million years ago in the form of two newly discovered creatures known as the (get ready) giant dwarf crocodile. This presents the oxymoronic conundrum – was this crocodile a dwarf that grew or a giant that shrank?
“These were the biggest predators our ancestors faced. They were opportunistic predators, just as crocodiles are today. It would have been downright perilous for ancient humans to head down to the river for a drink.”
Did Christopher Brochu, professor in the Department of Earth and Environmental Sciences at the University of Iowa and author of the research on this discovery, say our ancestors could have encountered giant dwarf crocodiles? Well, if you go back to the Hominini taxonomic tribe which dates back to at least 8 million years ago, he’s probably right – especially since the fossils were discovered in what is now Kenya, the accepted birthplace of the human species.
The fossils of Kinyang mabokoensis and Kinjang tchernovi (photos here) were discovered in the areas of the Lake Victoria basin and Lake Turkana basin respectively. The kinyang were true crocodiles, but belonged to the subfamily Osteolaeminae which includes modern dwarf crocodiles and slender snouted crocodiles. The modern African dwarf crocodiles have broad snouts and rarely reach a length of 4.9 feet (1.5 meters), making the smallest living species of crocodile. Despite its small size, the dwarf crocodile has evolved tools to protect it from predators – a heavily armored neck, back, and tail and bony skin on its belly and the underside of neck.
“They had what looked like this big grin that made them look really happy, but they would bite your face off if you gave them the chance.”
In the University of Iowa press release, Professor Brochu describes what the K. mabokoensis and K. tchernovi looked like. For starters, they typically grew to 12 feet (3.6 meters) in length, so these were dwarfs who became giants. One of the fossil specimens was a skull, which was “exceptionally broad and robust” and much wider than that of any living crocodile species -- dwarf or otherwise. The researchers found four unique characteristics that provided unambiguous support for these two to be classified as a new species -- occlusal patterns (pits in their teeth) in different teeth than other crocodiles; an unusual quadratojugal (skull bone); a subdivided lateral collateral ligament (a thin band of tissue running along the outside of the knee connecting the thighbone to the fibula) that is not found in any other crocodile; and a less than average number of teeth in the upper jaw. All of those characteristics together made Kinyang unique and gave it that ‘killer’ grin.
“Kinyang lived in the East Africa Rift Valley, in parts of present-day Kenya, in the early to middle Miocene period—a time when the region was largely blanketed by forests.”
Modern dwarf crocodiles are found living western Africa, primarily in the Upper Congo River Basin in what is now the Democratic Republic of Congo. That plus their relatively small size makes them less dangerous to modern land-dwelling humans of any size. On the other hand, the dwarf giant crocodiles spent most of their time in the dense African forests where they could easily blend into the ground cover and wait for their prey, which the researchers say was quite diverse and estimated to often be as large of even quite larger than the themselves. With plenty of food – possibly even some tasty archaic humans – and a land mass covered in lush forests perfect for an earth-toned beast to blend into, why did these giant dwarf crocodiles go extinct?
“Modern dwarf crocodiles are found exclusively in forested wetlands. Loss of habitat may have prompted a major change in the crocodiles found in the area.”
Loss of habitat that was caused by – you guessed – climate change. Brochu speculates that climate change 15 million years ago led to less rainfall in the east African region where the giant dwarf crocodiles lived. As the forests receded, they were left to live, nest, hide and feed in the grasslands and the less lush savanna woodlands which replaced them. Could the characteristics that made them unique – the broad skulls, unusual teeth and jaws and oddly positioned nostrils – have also made them unable to adapt or evolve to live in these new ecosystems? Brochu suggests that the changing environment definitely affected the dwarf giant crocodiles, but in an entirely different way.
“These same environmental changes have been linked to the rise of the larger bipedal primates that gave rise to modern humans.”
Humans! Could the prey have become the predator as the forest and climate changed to forms more suited for bipedal creatures with big heads full of brains in need of meat? Why didn’t they evolve into just plain old smaller, river-dwelling dwarf crocodiles? Brochu acknowledges that the extinction of the Kinyang is a mystery and requires more fossils and research to solve. In fact, more fossils might help solve a second mystery – why is there a gap in the fossil record between giant dwarf crocodiles, which ended around 15 million years ago, and the new species of crocodile African crocodiles that began showing up about 7 million years ago? Those species, like the famous Nile crocodile, thrive in modern Kenya – the ancient stomping grounds of the giant dwarfs.
The study, “Giant Dwarf Crocodiles From the Miocene of Kenya and Crocodylid Faunal Dynamics in the Late Cenozoic of East Africa” is published online in the journal Anatomical Record. It’s an ‘awfully good’ collection of facts, not ‘unbiased opinions’ that would interest any ‘wise fool’ interested in the Kinyang crocodiles, a ‘small crowd’ in the paleontology field who are nonetheless concerned about the ‘conspicuous absence’ of more information about the ‘giant dwarf’.
Not to mention oxymorons.