Weird Heads Month #14: Horns and Frills

We can’t go through this month without having an appearance from the most famous group of weird-headed dinosaurs: the ceratopsids!

Their distinctive-looking skulls were highly modified from those of their ancestors, with large bony frills extending from the back of their heads, various elaborate horns and spikes, enormous nasal cavities, large hooked beaks at the front of their snouts, and rows of slicing teeth further back.

And while typically depicted as purely herbivorous, ceratopsids’ powerful parrot-like beaks and lack of grinding teeth suggest they may actually have been somewhat more omnivorous – the Cretaceous equivalent of pigs – still feeding mainly on plant matter but also munching on carrion and opportunistically eating smaller animals when they got the chance.

Machairoceratops cronusi here lived during the late Cretaceous of Utah, USA, about 77 million years ago. Only one partial skull has ever been found belonging to an individual about 4.5m long (14’9″), but it wasn’t fully grown and so probably reached slightly larger sizes.

It had two long spikes at the top of its frill, similar to its close relative Diabloceratops but curving dramatically forward and downwards above its face. Whether they were purely for display or used in horn-locking shoving matches is unknown, but either way it was a unique arrangement compared to all other known ceratopsids.

Weird Heads Month #13: Many-Horned Mammals

The dinoceratans were a lineage of hoofed herbivorous mammals whose evolutionary affinities are a little uncertain, but may have been related to the South American meridiungulates. Found in Asia and North America from the late Paleocene to the late Eocene, they had bulky rhino-like bodies and were some of the largest terrestrial animals of their time.

Eobasileus cornutus was one of the biggest of them all, measuring around 2.1m tall at the shoulder (~7′) and living in the Western United States during the early Eocene, about 46-40 million years ago.

And it had a very odd-looking head, with six blunt ossicone-like horns, large sabre-like fangs, bony flanges on its lower jaw, a concave forehead, and a proportionally tiny brain for its body size. The horns and fangs were sexually dimorphic, much smaller in females, suggesting they were mainly used for display or combat between males.

Weird Heads Month #08: Nose-Forks and Handlebar Heads

Modern ruminants are the only living mammals with bony headgear, with four different  lineages each sporting a slightly different type: deer antlers, bovid horns, giraffid ossicones, and the prongs of pronghorns.

We still don’t actually know much about the evolutionary origins of ruminant headgear, although a recent genetic study suggests they’re all derived from a single common ancestral structure (and that deer antlers started off as controlled bone cancer).

And some extinct species were even stranger.

The protoceratids were an early group of North American ruminants whose relationships are uncertain, but may have been related to modern chevrotains. They were convergently deer-like in appearance, with teeth adapted for grazing on tough grasses – and along with having a pair of horns in the usual position on their heads, males also sported an additional pair of ossicone-like growths on their noses.

Synthetoceras tricornatus lived during the Late Miocene, around 10-5 million years ago, and was one of the largest protoceratids, standing about 1.1m tall at the shoulder (3’7″). Its two nose-horns were partially fused into a single long structure with a forked tip, which may have been used for sparring in a similar manner to the antlers of modern deer.

A colored line drawing of an extinct deer-like animal. It has a pair of horns on its head, along with a long horn on its nose that has a two-pronged forked tip.
Synthetoceras tricornatus

Meanwhile on a different branch of the ruminant family tree, closer related to deer and giraffes, a group known as the palaeomerycids independently developed a similar sort of extra head appendage – but at the opposite end of their skulls.

These ruminants were a little more heavily built than the protoceratids, and specialized in feeding on soft vegetation in humid forest environments. They were a highly successful group, existing for almost 30 million years, ranging across Eurasia, Africa, and North America, and even ventured into South America during the early phases of the Great American Interchange.

Males had two giraffe-like ossicones above their eyes, along with a third crest-like one at the very back of their heads. In some species this formed a single central “horn” shape, while in others it forked out to each side. They also often had long saber-like canine teeth similar to modern water deer and musk deer, which were probably used for fighting while their elaborate headgear was purely for visual display.

Xenokeryx amidalae lived in Spain during the mid Miocene, about 16 million years ago. It stood around 0.8-1m tall at the shoulder (2’7″-3’3″) and had a unique T-shaped “handlebar” crest which ended up inspiring its genus name – a reference to the similar shape of one of Queen Amidala’s headpieces in Star Wars, which was itself based on Mongolian imperial fashion.

A colored line drawing of an extinct deer-like animal. It has fang-like tusks protruding from the sides of its mouth, a pair of giraffe-like ossicones above its eyes, and a T-shaped handlebar-like crast on the back of its head.
Xenokeryx amidalae

Peltephilus

Peltephilus ferox, an armadillo from the Early Miocene of Argentina (~17-16 mya) that was similar in size to a large dog, probably around 1.5m long (5′). It had less solid armor than its modern relatives, with its bony osteoderms being arranged more like chain mail, loosely connected to each other and slightly overlapping, creating a much more flexible body covering.

Its most unusual features were the horns on its snout, convergently resembling the later horned gophers of North America. But unlike other mammals Peltephilus‘ horns were actually modified plates of its face armor, enlarged pointed osteoderms that were only connected to its skull by soft tissue membranes – meaning that after death they tended to fall off, and the exact number and position of them is still a little uncertain.

Its unusually broad snout and large teeth were originally interpreted as evidence of it being an active carnivore, but more recent studies of its anatomy have suggested that it was much more likely to have been a herbivorous or omnivorous digger, mainly feeding on underground plant matter like roots and tubers.