Prenocephale (Sloping Head) is a genus of pachycephalosaurid marginocephalian dinosaur that lived in the Nemegt Formation, Mongolia, 70 million years ago, during the Maastrichtian stage of the Late Cretaceous Period.
Prenocephale intimidated by Tarchia. The one on the lower left is male, as indicated by the keratinous bristles on his tail.
Prenocephale is a small animal, merely 2.2 meters (7 feet, 2 inches) long and 40 kilograms (88.2 pounds) in mass.[1] As a pachycephalosaur, the frontal and parietal bones of its skull are fused and thickened with bone deposits to form a prominent dome (in its case, forming a round, sloping shape, hence its name),[3] surrounded by crown of small, bony spikes and knobs. It resembles Stegoceras, a closely-related pachycephalosaur that lived 77.5 - 74 million years ago in North America, with a few differences, like some closed-up openings on top of the skull as well as the absence of paired grooves above its eye sockets.[4] Like its relatives, not much of Prenocephale is known aside from fragments of its skull, but it can be reasonably assumed to possess the standard pachycephalosaur body plan, with a short, thick neck, short arms that ended in hands with five fingers (of which only the first three have claws), broad hips, long legs, and a thick, heavy tail made rigid by tendons that were ossified (turned to bone), though this bundle of solidified bony rods does not necessarily make the tail especially bulky.[DN 1]
A Prenocephale nips at a juvenile Tarchia in an attempt to drive it away from an oasis
On Prehistoric Planet, Prenocephale and its relative Pachycephalosaurus are depicted without cheeks, in sharp contrast with ceratopsians like Triceratops and Pachyrhinosaurus, which are depicted with cheeks. According to paleontologist and anatomist Dr. Ali Nabavizadeh, pachycephalosaurs and other basal ornithischians had features consistent with those of lepidosaurs (lizards and tuataras), like short coronoid processes (the blade-like protuberances on either side of the mandible), similar buccal emarginations (the raised ridges that run along the outer side of the teeth next to the cheeks, defining the cusp tips and guiding chewing forces), foramina (blood vessel pits) concentrated rostrally (near the front), and thin, rounded, rostrally elongated labial dentary ridges (bone ridges lateral to the teeth). Their retroarticular processes (the bony walls that form the back of the temporomandibular joints, which connect the mandible to the skull) are noticeably long, and their pterygoid bones (which form part of the palate) have large flanges, indicating that their medial pterygoid muscles (important for mastication, the act of chewing) are hypertrophied, heavily developed compared to those of ceratopsids, stegosaurs, and ankylosaurs, which have retroarticular processes that are small or almost nonexistent. Overall, the idea is that pachycephalosaurs had simpler, more primitive teeth and a more basic lizard-like chewing style compared to the complex manner in which ceratopsians and more derived ornithischians chewed using their comparatively more advanced dental batteries. These basal ornithischians would have likely had lizard-like "lips" formed by large scales, but no cheek-like flaps connecting the upper and lower jaws.[AN 1][AN 2] Regardless of whether they had cheeks or not, current understanding has it that dinosaur cheeks are not like those of mammals given how, contrary to popular belief, dinosaurs did not need cheeks to hold food since they did not chew from side to side like mammals.[AN 3] Although at least some dinosaurs had skin covering the adductor muscles extending across their upper and lower jaws (some birds like condors do indeed have flaps of skin stretching across the sides of their mouths, while the nodosaurid Panoplosaurus of the Campanian Dinosaur Park Formation in Canada shows evidence of buccal flaps), no sauropsid (what is understood to be "reptiles", including avian dinosaurs) possesses cheeks or lips that are analogous to the more complex facial muscle anatomy of mammals.[AN 1][AN 2][TH 1]
Citing Dr. Ali Nabavizadeh's works as justification, Dr. Darren Naish had the show's pachycephalosaurs depicted without cheeks, instead only possessing large scales lining their jaws, resembling those seen forming the "lips" of lizards,[DN 2] fit for chewing food more like a lizard rather than engaging in the more complex mastication styles of ceratopsians and ornithopods.[DN 3]
Prehistoric Planet's Portrayal[]
Concept art by Gabriel N. Ugueto shows that the male Prenocephale were originally supposed to be brighter in coloration
On Prehistoric Planet, the Prenocephale are countershaded, their back riddled with tiny bumps, while stripes run down across the body. Their most defining feature, their keratin-covered domes, appear faint blue in a few lighting conditions when viewed from certain angles. The females have a dark gray back and light gray belly, while the males were intended to be depicted with brighter colors, including facial stripes and orange hindquarters, though this was ultimately darkened for the show and made even duller by dirt and ambient lighting.
Concept art by Gabriel N. Ugueto shows that the female Prenocephale were originally also designed with tail bristles
Concept art by Gabriel N. Ugueto reveals that the both male and female Prenocephale were supposed to have tail bristles, while the males would have been more brightly colored, sporting an orange back half. In the end, only the males retained tail bristles to differentiate them from the females, as their overall coloration was toned down in the final product.[PhP 1] Tail bristles (determined in a 2016 study to be highly modified scales as opposed to feathers due to the different morphology and anatomy of these structures)[5] are known in the primitive Psittacosaurus, a basal ceratopsian, and, though there is barely any evidence of such structures in others, some of the later, more advanced members of the ceratopsian clade are occasionally depicted with similar-looking filaments running down the back and tail (hence why the adult Pachyrhinosaurus males were depicted with such bristles in the sixth segment of Ice Worlds). This speculative characteristic is sometimes extended to the other marginocephalian clade, pachycephalosaurs like Prenocephale. These keratinized bristles likely served as an additional means of display.
Juvenile Tarchia disturbs a group of seven Prenocephale
The Ömnögovi is the largest aimag (province) of Mongolia, found in the south of the country, in the northeast portion of the Gobi Desert. Within this aimag is an area called the Nemegt Basin, known locally as the "Valley of Dragons" due to its rich fossil content. It encompasses three formations showing the states the area underwent throughout the Late Cretaceous, namely, the Djadochta (75 - 71 million years old), Barun Goyot (72 - 71 million years old), and Nemegt (70 million years old) Formations. Prenocephale lived in the last of the three formations, which showed evidence of a rich, humid environment with large river channels, tidal flats, and forests. However, the Nemegt Formation is also known to have undergone periodic droughts, and there is precedence for arid regions much like the Gobi Desert today existing in Mongolia during those times, thus somewhat justifying the depiction of Prenocephale living in a vast desert environment. Fittingly, Prenocephale is depicted as preferring to live around a small spring in the show, hidden within a canyon where they are less likely to be found and hunted by predators. Because of the old idea that pachycephalosaurs lived in elevated areas like mountain goats, Prenocephale was once believed to prefer high upland wooded areas. However, it is not portrayed that way in the series, and, as clarified by Dr. Darren Naish, Prehistoric Planet's lead consultant, Prenocephale escaping to higher ground in the second segment of Badlands is not meant to reference this old view, and it is a sequence simply inspired by the Saudi Arabian terrain where the story was filmed. Nevertheless, it is also said that dinosaurs (and most animals alive and extinct, for that matter) in rocky places were likely good climbers, adept at climbing slopes, either to escape predators or to hunt prey, with the great height and gravity itself being useful killing tools for them as they still are for birds of prey, certain big cats, and other hunters today.[DN 4]
Paleofauna[]
A Prenocephale gets chased by a Velociraptor up a cliff, right into an ambush
Prenocephale is one of the two pachycephalosaurs of the Nemegt Formation, the other being the smaller, flat-headed Homalocephale, which was previously theorized to be merely juvenile forms of their larger relative until actual young Prenocephale specimens were found with rounded domes, proving that both are different species.[6]Prenocephale also coexisted with similarly-small creatures like Mononykus and at least eight oviraptorosaurs, and would have faced threats from hunters like Adasaurus and other indeterminate velociraptorine dromaeosaurids, as well as troodontids like Borogovia, Tochisaurus, and Zanabazar.
It is believed that Prenocephale is a selective forager due to its mouth and premaxillary teeth not being as wide as those of its relative, Stegoceras. It is also suggested that they are omnivorous, feeding on plants and insects, like their relative, Pachycephalosaurus (which has theropod-like blade-shaped teeth in the front indicating a degree of omnivory, and, as shown in the fourth segment of Swamps, feeds on some insects).[2]
Evasive and Defensive Tactics[]
A Velociraptor chases a group of Prenocephale escaping up a cliff, aiming to single the most vulnerable target out
Given their small size, the Prenocephale are cautious, and hence travel with larger dinosaurs like Nemegtosaurus and the Mongolian Titan for protection from predators like Tarbosaurus. However, when panic rises within the herd, they may try to evade danger by using their small, agile form to escape to higher ground, though this, in turn, puts them at risk of being pursued by similarly agile predators like Velociraptor. Given how resources are limited in the desert, animals may be justifiably greedy and competitive over resources, explaining why the Prenocephale react with hostility when a juvenile Tarchia drinks from their oasis, growling, screeching, and nipping at the newcomer with their beaks as opposed to headbutting with their hardened skulls, though, given their small size, they were easily scared off when the Tarchia intimidated them by slamming its tail club on the ground, reminding them of its far greater size and power. This story, an idea by Dom Walter, the segment's producer, initially had the Prenocephale try to defend their secluded valley "spa" more aggressively than they did in the final version.[DN 5]
In the second segment of Badlands, on the way to a temporary oasis hidden behind a plateau riddled with canyons that form a massive maze, a group of Prenocephale are seen traveling with a herd of Nemegtosaurus and Mongolian Titans for protection. Suddenly, the herd is thrown into panic by a trio of Tarbosaurus, scaring the Prenocephale into running up a canyon to escape to higher ground, an option the sauropods cannot take as they try to travel through the maze as quickly as possible.
The Velociraptors approach the Prenocephale they fatally kicked off the cliff
“ Only the Prenocephale can escape to higher ground. And this is what the Velociraptors have waited for. Now, the Velociraptors can finally spring their ambush. ”
Unfortunately, this put them right where another type of hunter is waiting for them. As they ran up the slope of the canyon, a Velociraptors rushes in and pursues them, singling out one of the Prenocephale and pursuing it up a path where another Velociraptor is waiting. Upon reaching the ambush point, the other Velociraptor springs from behind the wall to kick the pachycephalosaur off the edge of the cliff to its death. As the trio of Tarbosaurus feed on a Nemegtosaurus that died during the stampede, the two Velociraptors, along with their chicks, descend from the canyon to feed on the fallen Prenocephale, a meal secured for the whole family.
Filming Location Some places in Saudi Arabia, like Al-'Ula city in the Medina Province and Tabuk City of the Tabuk Region[PhP 2]
A juvenile Tarchia is confronted by a small group of Prenocephale
In the fourth segment of Badlands, a juvenile Tarchia comes across a small spring hidden within a canyon, surrounded by seven Prenocephale. The ankylosaur walks through the group of pachycephalosaurs, which are surprised and displeased by the newcomer drinking some of their precious water. They growl, screech, and nip at the juvenile with their beaks, though the ankylosaur reminds them of its superior size and strength by slamming its tail club on the sandy ground, scaring the Prenocephale off and causing most of them to scurry behind a rock.
The seven Prenocephale watch two Tarchia juveniles drinking from their small oasis
“ Tensions often run high around an oasis. But a display of strength can prevent a dangerous battle. In the end, the Prenocephale are little more than annoying. ”
After the juvenile Tarchia and its companion get the adult Tarchia that owns the oasis to back off and let them have a share of the place, the Prenocephale watch the ankylosaur brothers drink from atop the rocks on the opposite side of the spring, unable to do anything about the situation.
Gallery[]
Trivia[]
Prenocephale is the only Nemegt Formation species to debut in the second season of Prehistoric Planet, as all the other featured Nemegt Formation inhabitants already appeared in the previous season.
Prenocephale is the only marginocephalian dinosaur featured on Prehistoric Planet that never got involved in intraspecific combat. On a more general note, it is also the only marginocephalian dinosaur never depicted using its headgear for any purpose, preferring to run from predators like Velociraptor (which is half the pachycephalosaur's weight) and nip at rivals with their beaks. By contrast, Pachyrhinosaurus, Pachycephalosaurus, and Triceratops are all shown using their heads for display, physical altercations, and, in the case of Pachycephalosaurus, a means to obtain food (as shown when one bumped a tree down to feed on the insects within).
However, given their conflict with a young Tarchia in the fourth segment of Badlands, Prenocephale is the only herbivore (as a member of a family that showed omnivorous traits, it still technically counts as a plant-eater) portrayed fighting another herbivorous species (the same cannot be said for Tarchia, which did not actually fight back, but managed to intimidate its foes). A close case involved one Ornithomimus trying to keep two Edmontosaurus away from his nest in the second segment of Ice Worlds, though both animals never actually made contact with each other, unlike the Prenocephale, which nipped at the young Tarchia until the juvenile scared them off by slamming its tail club on the ground.
