Across the globe, herds of giant herbivorous ornithopods dominate the landscape. However when trudging through the forests and swamps of tropical Asia and South America, observers will often come face to face with dinosaurs of a very different kind - the parrot-beaked ceratopsians. Owing to the diversity of ceratopsian evolution since the end of the Cretaceous, most spec-taxonomic schemes regard the Ceratopsia as a superorder with a single extant order, the Cenoceratopsia.

 

HISTORY
The ceratopsians first appeared in Early Cretaceous Asia and soon branched into two successful Laurasian families. The predominantly Asian Protoceratopsidae were comparatively primitive forms that were usually hornless or, at most, in possession of a small nasal horn. While staying small, they became exceedingly abundant in places like the arid plains of Mongolia.

 

Far more spectacular were members of the North American family Ceratopsidae which attained huge sizes and sported a dizzying array of facial horns, spikes and bosses. During the Campanian perhaps a dozen species of these frilled giants marched along the western shores of the interior seaway. However as the Maastrichtian progressed, ceratopsid diversity waned. The family made a comeback of sorts during the Paleocene and Early Eocene, evolving into spectacular behemoths such as Brontoceratops , the most massive ceratopsian ever known. Alas, these magnificent beasts were unable to cope with the climatic fluctuations of the Late Eocene and vanished at the start of the Oligocene.

 

At the same time however, their smaller protoceratopsid cousins were having a more productive time. They grew larger and stranger, moving into niches vacated by their recently departed cousins. In terms of higher-level diversity, the Late Oligocene was the heyday of the protoceratopsians when a variety of weird lineages could be found throughout the Northern Hemisphere.

 

As the Neogene dawned, a number of factors conspired against this parrot-beaked menagerie. The Haughton impact at the close of the Oligocene led to localized extinctions in Asia and practically wiped them out in North America. New kinds of advanced ornithopods appeared, providing stiff competition to the now scattered ceratopsian populations. Finally they may have had difficulty coping with the spreading grasslands. The narrow beaks and slicing dentition of most species was great for tearing into tough bark and cycads, but considerably less efficient at processing grass than the square bills and grinding teeth of hadrosaurs.

 

While the other families dwindled, one line of protoceratopsians abandoned the characteristic scissor-teeth of their ancestors allowing them to exploit a wider range foods (although they never produced a specialised grazer). These were the Cenoceratopsia which by the Late Miocene had regained much evolutionary lost ground. They soon became the dominant large browsers of southern Eurasia and made headway into Africa. During the Pliocene, they entered North America and marched across the Panama isthmus to become established in South America for the first time (as far as we
know) in ceratopsian history.

 

Then came the climatic seesaw that was the Quaternary. The lush woodlands which the ceratopsians favored appeared and vanished with the ebb and flow of the glaciers to the north. Today the cenoceratopsians are no longer present in North America, Africa and most of northern Eurasia. However they continue to thrive in the warmer parts of Asia and throughout South America.

 

FEATURES
One glance at its homely face is enough identify the creature in front of you as a ceratopsian. Jutting out the back of its skull is a frill of bone formed by the parietals and squamosals. This frill can be used for display as well as providing an extended surface area for huge adductor muscles, giving the animal a formidable bite. A unique bone called the rostral sits in front of the premaxilla which, when combined with the lower predentary, creates a narrow beak.

 

Members of the extant clade Cenoceratopsia share a number of features which separate them from their protoceratopsian ancestors. The ischium is now fairly straight, losing the pronounced downward curve. On the face, many of the ornamental features of the long extinct Ceratopsidae have convergently re-evolved including horns on the nose and brow. Unlike the smooth-edged frill of protoceratopsians, those of cenoceratopsians may be decorated with prominent parietal knobs and epoccipital spikes.

 

The most characteristic feature is however in the teeth. The tooth batteries of early ceratopsians were arranged to form a set of vertical blades. In effect, they chewed their food with a set of garden shears---a trait which probably allowed them to subsist on tougher vegetation than their contemporaries. However, it is difficult to imagine this mechanism as being anywhere as effective as the grinding batteries of hadrosaurs.

When the cenoceratopsians appeared in the Late Oligocene, their dentition progressively shifted towards a duckbill-like configuration where the crowns of the teeth rasp against each other to crush and grind plant food. This made chewing far more efficient than in earlier designs and was probably the key to their success. However, the teeth of cenoceratopsians can easily be distinguished from those of hadrosaurs in being fewer in number, more robust in form and are two to four times larger relative to body size. The teeth often bear prominent cusps and ridges which helps them to process plant matter that most ornithopods consider unpalatable.

PLATEOCEROTIA (Dawnhorns, megahorns)
Fairly primitive and generalized cenoceratopsians that are currently restricted to Asia but include the giant extinct monocerotids of North America. All plateocerotians possess a well-developed nasal horn or series of nasal hornlets as well as parietal and epocciptial spikes on the frill. They have a fairly long, low-slung bodies and short, down-curved tails. Unusually, the hatchlings are born with one or two pairs of large fang-like premaxillary teeth which may be retained, reduced or lost in the adults.

 

PLATEOCEROTIDAE
This Asian family contains two living species that are characterized by a total lack of osteoderms and unusual crushing dentition. The nasal horn is large and unusually broad based. They are creatures of dense tropical forest and woodlands, using their powerful teeth to break open the fallen seeds and nuts of rainforest trees.

The dawnhorn is a 4 metre long cenoceratopsian that dwells in the forests and woodlands of southern Asia. Males of this species have a curious, laterally flattened nose horn, which flushes bright yellow-orange during the mating season and has inspired this creature's common name.

 

These ceratopsians root around on the forest floor, consuming fallen branches and fungi whilst browsing on low foliage in clearings and at the forest edge. Their specialty, however, is in the consumption of the tough fallen fruit of several kinds of rainforest tree.

 

The most remarkable feature of the dawnhorn is in the mouth. A pair of stout, triangular premaxillary teeth are present in the roof of the mouth while the cheek teeth are massive and robust. In short, the dentition of the dawnhorn has become a giant nutcracker and it is one of the few animals capable of tackling a fruit as intimidating as the zlatkonut.

The half-dozen or so species of zlatkopalm (Marjanophytaceae) are a relict family of unusual primitive angiosperms found only in tropical Asian lowlands. These remarkably ugly, foul-smelling and fast growing small trees or bushes produce immense fruiting bodies all year round. These so-called zlatkonuts are protected by an incredibly resilient spiny husk, superficially similar to a WWII naval contact mine. The dawnhorns eagerly snatch up these fruits when they fall to the ground or use their powerful beaks to violently rip them from low-growing species.

Once in a dawnhorn's mouth, a powerful biting action brings its teeth to bear on the husk and the zlatkonut is soon noisily cracked open. The ceratopsian then feeds on the stuff inside, a pulp, which contains the seeds of the zlatkopalm. These pass through the dinosaur's digestive tract to be deposited on the forest floor a few days later within a pile of beautiful, nutritious poo. The dawnhorn is thus a vital element in the reproduction of these plants, which is why the zlatkopalms do not grow in otherwise suitable habitats where these ceratopsians are absent.

The auryngo or sunhorn is a subspecies of dawnhorn that was at first mistaken for a species of its own by early specbiologists. The Auryngo lives only in the Terai region (southern Nepal) while P. soloriens soloriens is more widespread, and can be found throughout mainland Southeast Asia. At least two more undescribed subspecies dwell on the islands of Sumatra and Borneo whilst an entirely new Plateoceros species has recently been discovered in southern India.

FURCICERATOPSIDAE

The furciceratopsids form the largest family of Asian ceratopsians, with over a dozen species, ranging from small forest dwellers to the giant megahorns. They have generalised dentition, a large narrow nasal horn or series of hornlets and prominent jugal spikes. Most have spiny or stud-like osteoderms set in their scaly hide. They tend to be unfussy feeders, eating any greenery they can easily get to.

 

Most of the larger species are known to be extremely nearsighted and bad-tempered. Even giant priscataurs will usually give an adult megahorn a wide berth. Smaller forms on the other hand can be extremely shy and cryptic.

Indian megahorns, the largest living furciceratopsids, range from eastern India to the shores of the South China Sea. Females and young live in small herds whilst adult males are usually solitary. Their preferred habitat is grassland and open areas in forests, usually close to a watercourse where they wallow and bathe. Its powerful beak can demolish even the toughest of plants.

 

Research suggests that the extracts of the Megahorn's horn possesses an extremely potent aphrodisiac quality and could form the basis of a highly lucrative pharmaceutical trade.

 

 

 

(fig. 3) Indian megahorn, Fuciceratops grandis (South and Southeast Asia)

Spec is plagued by cryptic ceratopsians! While the frill-tusker/till-cheek dinoceratopsian debate rages on in South America, this strange little Indian dinosaur has gone virtually unnoticed. Known only by its Latin name Terramoloch spinifer, this enigmatic ceratopsian long frustrated specbiologists by refusing to fit in with any other ceratopsian clade. Many believed (and some still maintain) that T. spinifer is a Eurasian dinoceratopsian, but with the aid of mitochondrial DNA studies, we have concluded that T. spinifer is, in fact, a close relative of the Indian megahorn.

 

(fig. 4) Terramoloch spinifer (South Asia)

To compare the massive megahorn to the tiny Terramoloch at first seems as ridiculous as comparing the little herbivore with the frill-tusker, but a number of physiological, as well as genetic features support this theory. Firstly, the branching nasal horn is diagnostic of Furciceratopsidae, the clade to which the megahorns belong. Also, the enlarged, curved jugal horns (once touted as links to the dinoceratopsians) are present in many megahorns, including the Indian megahorn. Even the bizarre covering of spiny scutes, unique among ceratopsians, is present (though to a much lesser degree) in young megahorns.

The habits of T. spinifer are largely unknown, but this denizen of the high plateaus of India and Nepal seems to be a low-level browser, feeding mostly on roots and shrubs, p-Rhododendron being this species's food of preference. T. spinifer's mating and child-rearing behaviors are unknown.

POTAMOCERATOPSIA (Behomoths)

 

This suborder contains only a single family which might better belong with the closely related brachioceratopsians.

POTAMOCERATOPSIDAE
The Potamoceratopsids are large semi-aquatic dinosaurs that roam the bottom of rivers and lakes if southern Asia in large herds. Each of the major tropical asian river systems plays host to at least one species of these aptly named river behemoths. They share several features with the Brachioceratopsia, including a reduced frill, a straightened sacral region and a number of biochemical similarities. However their massively built skull, muscular tail, short neck and stubby forelimbs clearly separates them from their sauropod-like cousins.

 

Potamoceratopsids are massively-built animals that spend most of their lives submerged in water. Their eyes and nostrils are positioned at the tops of the skulls and protrude from the water when these dinosaurs rest near the surface. They feed primarily on aquatic plants but will sometimes come onto land to browse after sundown.

The Indian river behemoth is the largest behemoth species, and can weigh up to 8 tons. Behemoths have massive heads with short frills, and long barrel-like bodies that end in a flattened tail that is used for swimming. The legs of behemoths are rather small, and they usually move slowly on land. Like the brachioceratopsids, behemoths don't have true horns, though males of some species have horny growths above the nostrils and eyes. These creatures often rest near the surface with only eyes and nostrils protruding.

 

 

 

 

(fig. 5) Indian river behomoth, Potamoceratops obesus (South Asia)

The enigmoceratopsians are basal brachioceratopsians which were at their most diverse in the Late Miocene. Today they are restricted to a single diminutive species from Southeast Asia.  (See, the Horned Riddle)

These are the giants of the Cenoceratopsia, enormous graviportal high-browsers of tropical Asia. Along with the pseudosauropods of South America and the extinct indricotheres of Arel, they have done a marvellous job in ripping-off the sauropods . Their skulls are light-weight (although retaining a pair of stubby brow horns) allowing the greatly elongated neck to raise the head high into the trees. All four limbs are pillar-like; the forelimbs are elongated and are now held straight under the body, losing the characteristic "bow-legged" posture of other ceratopsians.

 

The tooth-batteries of brachioceratopsids have also been reduced in size as a weight-saving feature and the brachioceratopsids have reverted to a system once used by their distant psittacosaur ancestors but long since abandoned by the rest of the Cenoceratopsia. They swallow stones, storing them in the gizzard to grind up plant-matter after a brief chewing-phase in the mouth.

 

Young and adolescents stay close to one another whilst the adults are generally solitary. Breeding may occur throughout they year. A male in "dinomusth" will aggressively clear an area of rival bulls before trumpeting loudly to attract receptive females. Egg-laden females gather together in small herds before depositing their brood in pits on the forest edge and going their separate ways. The newly hatched young frantically scamper into the darkness of the undergrowth where they spend up to five years before leaving to form an adolescent herd.

 

Unless in the mood for mating, adult brachioceratopsians are the most peaceful of all ceratopsians, lacking the jittery shyness of the smaller forms and the psychotic aggression of the large low-browsers. When one flick of your leg can send a priscataur flying, you can afford to be docile.

Their distant protoceratopsian ancestors made a brief foray with high-browsing during the Oligocene (producing such giants as
Titanoceratops ). We now know that these were not closely related to the brachioceratopsians as once believed.

Standing before an adult 15 metre long balandaur gives takes one to new levels of humbleness. At up to 14 tonnes, this is probably the largest living ornithischian, surpassing even the giant neotropical pachamacs.

 

Balandaurs may be spotted throughout the Indian subcontinent to as far east as the Indochinese peninsula but are not found north of the Himalayas. They can be found just about anywhere where they are trees, roaming far and wide in search of fresh greenery leaving a trail of dung and destruction in their wake - providing opportunities for a host of other organisms.

 

 

The greater undaur is nowhere near as large as the towering balundaur (10 metres long, 7 tonnes) but is still an impressive animal, nonetheless. Unlike its larger cousin, the undaur prefers to stay close to forested environments, venturing out onto the wooded plains only in particularly bad years. As a result of it's wider distribution coupled with a more restricted habitat requirement, up to six different subspecies of this creature have cropped up in India, Sri Lanka, China and Southeast Asia.

 

 

The placement of this remarkable, little known animal in the same genus as the greater undaur is a point of some contention. Found only in the dense upland forests of Sumatra, this animal looks to be nothing more than an overgrown hatchling greater undaur (c.4 metres long, c.500 kg). Like a hatchling, the body is compact and dumpy whilst the brow-horns, epioccipital studs and dorsal scales (which all other brachioceratopsians acquire when over 2 m in length) have not developed. It scales also bear an almost identical cryptic spotted pattern to the juvenile greaters.  

 

However, one of these "big-babies" was witnessed laying a clutch of 25 eggs which were unfortunately plundered by an unknown raider before they hatched (whatever it was also chopped/bit off the heads off the two field researchers who were watching over the nest). All in all, this animal would appear to be an extreme case of neoteny and it has been suggested that it is no more than a mutant form of the greater undaur, a subspecies of which occurs in the Sumatran lowlands.

DINOCERATOPSIA (Dinoceratopses, tuskhorns, and ramskulls)
Dinoceratopsia represent a group of South American survivors of a largely extinct North American radiation.

Text by Brian Choo,  Daniel Bensen, and Matti Aumala