Outwardly, viriosaurs closely resemble such late-Cretaceous ornithopods as Thescelosaurus, with small, birdlike heads atop long necks, long tails, and (generally) a bipedal stance. This resemblance to familiar ornithopods is quite misleading, however. In their 65 million years of evolution, the viriosaurs' internal anatomy has gone through some changes.
Most of the features that distinguish clade Viriosauria from their basal ornithopod ancestors are cranial. Unlike the hypsolophodonts of the Cretaceous, the viriosaurs lack teeth on the premaxilla, bearing an iguanodont-like battery of beak and ridged, grinding cheek teeth. The premaxilla, itself, is large and fused with the nasal to produce a large, broad bone (called the "facial") that is often expanded into knobby display structure. In addition to these cranial features, viriosaurs are also generally possessed of an enlarged middle toe that gives these little herbivores a splay-footed appearance. These claws are probably a primitive shared feature of the entire clade, although several lineages have lost them.
Viriosaurs are most common in their homeland of South America, but have made significant inroads into North America in the wake of the Great Faunal Interchange. For the most part, these dinosaurs occupy small herbivore niches, and are most common in forests. The clade has produced some larger, grazing forms, but most of these were driven to extinction by the hadrosaur torgs.
VIRIOSAURIDAE (Viries)
Most viriosaurs fall into this family of small, bipedal herbivores. All viriosaurids have four-fingered hands (although digits I and IV are often reduced) and the enlarged inner toe. Viriosauridae is a long-lived clade, with fossil representatives as old as 20 million years.
The spectacled viri is a common lower-story browser in the forests and jungles of central South America. The largest species in genus Viriosaurus (1.5 meters long in adult females), the spectacled viri is most at home in the cooler cloud forests nestled within the Andes. These little browsers can often be seen along the forest margins at dusk, when the males venture onto the pampas to call for prospective mates.
(fig. 1) Spectacled viri, Viriosaurus ("Marasaurus") sinkkoneni (Central and western South America)
Viriosaurs spread rapidly northwards during the Pliocene, as the Panama landbridge became firmer. They are now the principal small herbivores of most of southern and central North America, but these warm-adapted ornithopods cannot diversify much beyond the snow belt.
In the valleys of the Sierra Navada mountains lives the lesser western viri. These viriosaurs vary greatly over their range (pictured here is a male of the Stanislaus subspecies) but all are rather small (no longer than two meters), with long legs and necks and short, robust beaks for cropping tough vegetation.
(fig. 2) Lesser western viri, Viriosaurus occidentalis (Central and western North America)
Song's viri is a particularly small, lively creature with a high pitched call. These creatures eat tubers and low-growing plants and have been reliably reported to dine upon grubs and other invertebrates. These viries are common during the spring or summer, but become much rarer during the winter. Whether this species hibernates or simply migrates is unknown.
(fig. 3) Song's viri, Viriosaurus songi (Western North America)
The yellow-headed viri is a deep-forest browser common in forests all over central and western North America. Yellow-heads are selective feeders and dart their heads in and out of the underbrush, searching for the tastiest bits of foliage.
(fig. 4) Yellow-headed viri, Sylvapascis vulgaris (Central and western North America)
KRANILIDAE (Cranili)
Ranging from only a meter in length to nearly four, these marsh-loving herbivores are common in the warmer, wetter parts of South and Central America. Their bodies are generally robust, with powerful hind legs, and very small, four-fingered forelimbs. The neck is long and muscular, anchored by a series of enlarged neural spines over the shoulders. In the larger species, the inner toe-claw is often reduced.
As one travels south across the Americas, one notes an obvious change in fauna from the Eurasian therizinosaurs to the hadrosaurids, and finally to these viriosaurs, bipedal ornithopods that have migrated from South America. Thus, while the bogs of Canada harbor tirgs, the swamps of warmer America are home to sludgers, the bayous of southern and Central America are the domain of the cranili.
The long-necked, bottom-heavy cranil form is ubiquitous in the marshy areas of central and South America. The common (or striped) cranil ranges across Central America, with vagrants relatively common in the brackish swamps of southern North America. Cranili eat a variety of riperine vegetation and (during times of drought) will venture from the water to strip small trees of their leaves.
(fig. 5) Common kranil, Kranilis russelae (Southern North America and Central America)
Riparisaurs (Riparisaurus amazoniensis) are the most common small herbivores of the Amazon rainforest. These little creatures weave and doge through the trees, feeding upon vegetable detritus and avoiding the watchful eyes of the jagulars.
(fig. 6) Riparisaur, Riparisaurus amazoniensis (Central South America---Amazon)
Some North American kranilids (genus Javalinoides) have abandoned the water-loving lifestyle of their ancestors and have colonized the arid American Southwest. The rooter (Javalinoides robustus ) is a 2-meter-long, heavily built viriosaur that inhabits the dry grasslands of the Great Valley, where the Rockies split into two mountain ranges (the Coastal Range and the Sierra Nevadas), leaving a long track of flat land in between. Rooters feed on the roots of the plants growing in the Valley, and tend to congregate around rivers.
(fig. 7) Rooter, Javalinoides robustus (Southwestern North America)
LEVIPODIDAE (Levantadores)
Endemic to South America, the levantadores are the last remnants of an archaic radiation of giant viriosaurs that achieved some successes during the Oligocene and Miocene. Extinct levipodids are thought to have grown to lengths of nine meters, but no modern species is longer than six.
These viriosaurs are grazers, picking through the pampas for tubers and weeds, leaving the bulk of the grass to torgs. Most species have long, horse-like snouts, with broad facial bones, allowing them to graze while keeping their eyes above the grass, watching for predators. Levantadores possess only three fingers, and their inner toe bears a normal-sized claw. Many of the larger levipodids are quadrupeds, spending most of their time on four legs.
At 6 meters in length, the levantadores are the largest viriosaurs on the South American pampas. Grazing on all fours, levantadores will rear up on their hind legs to escape predators. This transition between bipedal and quadripedal plant eater has happened a number of times in dinosaurian evolutionary history, and the levantadores are thus quite reminiscent of the much more primitive Lesothosaurus of the Jurassic.
(fig. 8) Levantador, Levipodus philogramis (Southern South America---Pampas)
The 3-meter-long levantino is a smaller relative of the six-meter-long Levantador. These are most southern-dwelling of the levipodids, and live upon the high grasslands of Patagonia.
KENTROPODIDAE (Kentropods)
Kentropods are the most highly derived and unusual of the viriosaurs. With the exception of Dracorhea, the kentropods are small omnivores and insectivores, mostly of thickly forested areas.
Kentropods are immediately recognizable from other viriosaurs in have 3-fingered hands that bear large curved claws that are also present on the feet.
This 2 metre long species is common on the rainforest floor as well as the large tracts of degraded land created by pseudosauropod herds. The hookjaw kentropod is immediately recognisable by its greatly expanded, spike-like predentary. It is perhaps the most predatory of the kentropods, but still takes fruit and some leaves. It hunts mammals and small reptiles, often using it's claws and uniquely adapted beak to pry open rotting wood to expose prey or to impale them in their burrows.
(fig. 9) Hookjaw kentropod, Kentropus therizinorhynchos (Southern South America---Patagonia)
The Caribbean winklecracker (Klinebergella carcinovorax) is the northernmost-dwelling of the kentropod species and aslo the smallest, seldom exceeding a metre in length. This species is common along the Caribbean and Yucatan coastlines of South American.
The winklecracker hunts along beaches, and at low tide out onto the reef flats, for the marine bivalves and snails that form most of its diet (although the species has been observed to eat fruit, and will frequently take any crabs it discovers whilst hunting).
(fig. 10) Caribbean winklecracker, Klinebergella carcinovorax (Central America and Caribbean)
The winklecracker is, in all aspects of its anatomy, a beach-comber. The wrists of kentropod viriosaurs (as opposed to those of maniraptors) are flexible enough that the winklecracker can dig, turn small coral boulders and debris, and handle prey---certainly a useful adaptation in the winklecracker's unique niche. Shells and flesh are gripped between four tusks (convergently similar to those of the Australian rhyncoraptors) then crushed by the powerful flattened beak and swallowed.
This combination of kentropod and general dinosaurian features - beak, hands, and gizzard - has enabled the winklecracker to occupy a niche no animal in Home-Earth has colonized---that of a large shore-dwelling molluscivore. Home-Earth shorebirds, for example, would not be capable of bearing the extra weight of shell and still be able to fly efficiently, and other species lack the crushing beak, and digging adaptations, that make a diet of large shelled molluscs possible.
(fig. 11) Head of Caribbean winklecracker
Mainland-dwelling winklecrackers usually live in small family groups. Those on islands and in more marginal habitats tend towards more solitary behaviour.
(fig. 12) Feeding winklecracker
Despite its common name, the largest of the kentropods is probably more closely analogous to our world's Neotropical camelids rather than the rheas. It dwells in arid montane areas along the length of the Andes but also occurs at sea level in Tierra del Fuego. Dragon-rheas move in small herds made up of one male and up to a dozen females and their young. They are skitterish animals that will flee at great speed at the slightest hint of danger.
(fig. 13) Dracorhea, Dracorhea gracilis (Western South America---Andes)
(fig.14) Dire rhea, Diarhea marjanovicoides (South American lowlands south of the Tropic of Capricorn)The awe-inspiring expanse of the South American grasslands plays host to a wide range of deadly animals, the majority of which are theropod dinosaurs. However, there is one very different kind of killer on the pampas that can pose a dreadful risk to the human spexplorer. For this endless golden vista is the domain of the dire rhea, a notoriously bad-tempered and exceedingly unpleasant kentropod viriosaur. Although commonly associated with the grasslands, this adaptable ornithopod can be found in a variety of habitats including Antarctic beech-forest, semi-desert and rocky shores.
The dire rhea is an impressive animal that stands taller than a man. It bears a certain similarity to the unrelated old-world vulgures, which fill a broadly similar niche on the African savannah. Like other kentropods, they are formidably armed with wicked claws and are fast runners. It shares the erectile filamentous scales of it’s highland cousin, the dracorhea. These are highly developed in Patagonian animals, helping them to keep warm during the bitterly cold winters.
Dire rheas are highly omnivorous and will eat just about anything with a veneer of nutritional value. Small vertebrates such as mammals and lizards seem to be their favoured repast but they will also gobble down eggs, insects, leaves, seeds and fruit. They are efficient carrion-feeders, aggressively driving off other scavengers and using the narrow heads to probe the carcass for hard-to-reach bits of flesh. They appear to be quite intelligent and innovative, sometimes burying food in caches for future consumption. Dires on the Patagonian coast will wade into the shallows to pluck gastropods off kelp fronds or winkle for crabs. Those on the plains often follow large herbivores, both to snatch up small animals disturbed by their passing as well as rumaging through their dung for insects and undigested seeds. Although not primarily predaceous, they can easily dispatch a human-sized animal if the opportunity presents itself.
Adult dire rheas usually exist in mated pairs, the sexes are similar. Their way of life changes drastically as the year progresses. During the drier months, they are highly nomadic, roaming far and wide in search of suitable food, sometimes gathering in large feeding congregations around a carcass or watering hole. With the onset of the rains, breeding pairs of dire rheas soon adopt a sedentary lifestyle, staking out a nesting territory of between 100-200 square metres, usually near a reliable water source. As permanent freshwater is at a premium in many parts of the southern Neotropics, competition for prime nesting-territories is understandably intense and violent.
Both animals consume a far greater quantity of water than is needed for their survival during this period. Although, like other archosaurs, dire rheas do not urinate, the surplus water quickly passes through their excretory system, maintaining it’s clear liquid state. At the same time, a dietary increase in fruits and pond algae soon makes their faeces exceptionally runny. Water and faeces meet and are churned together in an enlarged colon where it is mixed with glandular secretions, the end result being a foul, odorous greenish-brown fluid. The raw stench of this liquid or “poojuice” is overpoweringly strong and is akin to rove-beetle spray combined with a very stale Indian curry plus doggie droppings.
(fig. 15) Spring is in the air by a small lake on Chiloe Island as pair of dire rheas mark their territory and reinforce their pair-bond with a charming nuptial ritual. After consuming mass-quantities of water, the ornithopods prance about their turf together, cawing loudly as they spray poojuice on everything in sight with breathtaking synchronicity. The noise of their cries (and flatulance) along with the stench of their sprayings give ample warning to any other dire pairs in the area that this stretch of lakeshore is occupied.
(fig. 16) A picture of the same stretch of lakeshore, taken several days later at twilight, reveals one of the most haunting sights on Spec - the ground lit up by glowing trails of dire rhea poojuice. The green glow is caused by luminescent bacteria whose spores were injested with the lake water. A glandular secretion mixed in with the poojuice causes these bacteria to flourish once expelled, creating this vivid display of light.
Only a minority of pairs produce luminescent poojuice as the bacteria only thrive in areas with constant moisture and a relatively mild temperature (such as on this lakeshore). However, those that do enjoy a significantly higher success rate in raising their offspring and as a result, these sites are much sought after and fiercly contested. Precisely what kind of advantage is brought about by glowing poo is a mystery. Perhaps the light attracts insects that have a similarly luminescent breeding display, providing additional food for the juveniles. Alternatively, as the substance readily clings to anything that touches it, it creates a deterrant to predators for whom glowing green and stinking to high heaven would be a severe handicap to successful hunting.
Pairs of dire rheas become exceedingly aggressive and combatative during this time, even more so once they begin nesting, and will attack anything they perceive as a threat to their offspring. They will maliciously coat intruders with their noxious excretions, following up with a vicious flurry of pecks and kicks to those that fail to take the hint. Even magnoraptors, pachas and stormriders have been known to be subjected to this treatment although the kentropods are not suicidal and will retreat if a large, dangerous opponent appears unswayed by the initial spray-attack.
While getting sprayed in the line of field-research is not uncommon, several spexplorers have sustained serious and sometimes fatal injuries when venturing too close to a dire nest. There can be few deaths on Spec more stomach-curdling than a prolongued and agonizing (not to mention messy and noisesome) attack of the dreaded dire rhea! This is made especially frightening when out in the field, where one is naturally deprived of the facilities that one would normally seek out during such a biological emergency.
"Spineback kentropods" [Kentropodidae incertae sedis]
Known only from eyewitness accounts, the spinback kentropod is probably a kentropodid, but its affiliations within this family are unknown.
The 1.2 metre long spineback kentropod is rare species only known from a few specimens and photographs that dwells in dense tropical upland rainforest. It is an insectivore of the forest floor, apparently using its beak and elongated claws to search for food amongst leaf litter or to winkle bark beetles out of fallen logs.
Despite their formidable appearance, the row of quill-like scales along the back are actually quite soft and pliable.
(fig. 17) "Spineback kentropod"
Brian Choo, Daniel Bensen, and Drhoz
,=V. sinkkoneni
(Spectacled viri)
,=|
| `=V. occidentalis(Lesser
western viri)
,=Viriosaurus=|
| `=V. songi
(Song's
dryad)
,=Viriosauridae=|
| `=Sylvapascis vulgaris
(Yellow-headed viri)
,=|
| | ,=Kranilis russelae
(Cranil)
| `=Kranilidae=|
| | ,=Riparisaurus amazoniensis
(Riparisaur)
| `=|
| `=Javalinoides robustus
(Rooter)
,=|
| | ,=L. philogramus
(Levantador)
| `=Levipodidae=Levipodus=|
| `=L. sinkkoneni
(Levantino)
=Viriosauria=|
|
,?~Spineback kentropod
`=Kentropoidea=|
| ,=Kentropus therizinorhynchos
(Hookjaw kentropod)
| ,=|
| | `=Klinebergella carcinovorax
(Caribbean winklecracker)
`=|
`=Dracorhea gracilis
(Dragon-rhea)
