“Horns” seem to have convergently evolved multiple times in crocodiles over the last few million years, including in a couple of living species. These triangular crests are formed from the squamosal bone, just above their ears, and tend to be a sexually dimorphic feature used in territorial displays between males, serving to make them look bigger when they arch their necks.
But there’s another horned crocodilian known from much earlier in the Cenozoic – and this one was an alligator!
Ceratosuchus burdoshi lived in Colorado and Wyoming in the western United States during the late Paleocene and early Eocene, about 57-56 million years ago. It was a fairly small alligator, around 1.7m long (5’6″), with a broad snout featuring sharp teeth at the front and blunter teeth further back – an arrangement that suggests it was a generalist predator eating a variety of small prey, using those teeth to first grab and then crush whatever it managed to catch.
It also had large blade-like osteoderm armor on the back of its neck, which may have been arranged in line with its “horns” to make its visual displays look even spikier.
Along with their weird giant birds, the islands of New Caledonia were also home to a small crocodilian unlike any alive today.
It was one of the last known members of a lineage of crocodiles known as the mekosuchines, which originated in Australia during the early Eocene about 50 million years ago and later island-hopped out into the South Pacific — mostly around the Coral Sea, but with some making it as far as New Zealand. By the start of the Holocene, about 12,000 years ago, they’d already declined and disappeared from the vast majority of their range, with only a few isolated island species remaining.
Named Mekosuchus inexpectatus, the New Caledonian mekosuchine was only about 2m long (6’6″), just slightly bigger than the modern dwarf crocodile. It was much more terrestrial than living crocs, spending most of its time on land, and it had teeth in the back of its jaws that were specialized for crushing, suggesting it mainly preyed on hard-shelled invertebrates such as snails and crabs.
Based on its limbs anatomy it may also have been able to climb trees. Although this idea was ridiculed when it was originally suggested back in the 1990s, a more recent discovery has shown that modern crocs can actually climb trees too.
Like with many other Holocene island species, the extinction of Mekosuchus inexpectatus seems to be directly linked to the arrival of humans, who reached New Caledonia around 1500 BCE.
Bones in archaeological kitchen waste sites show that the settlers actively hunted and ate Mekosuchus, but dating of the last known remains is uncertain. The most generous estimate is actually as recent as about 300 CE, so much like Sylviornis these small land crocs may have persisted for some time before finally going extinct.
Did you know some crocodiles have “horns”?
Formed from the corners of the squamosal bone at the back of their skulls, just above their ears, these structures are seen in living crocs like the Cuban crocodile and the Siamese crocodile, as well as some fossil species.
But perhaps the most impressively-horned croc was Voay robustus here.
Voay lived on the island of Madagascar during the Late Pleistocene and Holocene, between about 100,000 and 2,000 years ago. At about 5m long (16′5″) it was similar in size and build to a large male Nile crocodile – but despite this resemblance its closest living relative is actually the much smaller dwarf crocodile.
It had a fairly short and deep snout and chunky limbs, adaptations associated with a more terrestrial lifestyle that suggest it was specialized for hunting its prey on land rather than just at the water’s edge.
Much like modern horned crocodiles its particularly prominent horns were probably used for territorial displays, and may have been a sexually dimorphic feature with big mature males having the largest examples.
Voay’s disappearance just a couple of thousand years ago may have been the result of the arrival of human settlers on the island, either from being directly hunted or due to the large native species it preyed on also going extinct around the same time.
Boverisuchus magnifrons*, a crocodilian from the early Eocene of Germany (~50-40 mya). Reaching about 3m long (9′10″) it was much more heavily armored than its modern cousins, with an interlocking “exoskeleton” of bony osteoderms covering its body and limbs – leading to it being given the nickname “panzer croc”.
It was adapted for walking and running on land, with relatively long legs and surprisingly hoof-like claws. It may even have carried its weight directly on these hooves similar to mammalian ungulates.
And if that’s not unusual enough, its hind leg musculature suggests it also might have been capable of short bursts of bipedal sprinting.
[ * Originally known as Pristichampsus rollinatii before being reassigned in 2013.]