Living hadrosaurs can be divided into two broad groupings. The neohadrosaurs are, despite their name (which refers to their diversity in the New World), the older and more conservative of the two and are found throughout the Americas and the eastern half of Eurasia (The other great hadrosaur group, the ungulapedes , will be dealt with later). They first appear at the start of the Eocene in North America and are probable descendents of flat-headed Maastrichtian giants such as Edmontosaurus. In a very short space of time, the clade had spread into Eurasia and South America.(fig. 1) Eastern galumph, Galumphia hebes (South-eastern North America)Their first wave of expansion in the Eocene was to be a false start. The climatic turmoil at the end of this epoch ended their brief foray into Gondwana while their diversity in Eurasia mysteriously waned as the Oligocene progressed. In North America, evolution continued unabated and they branched into a host of spectacular lineages from giant swamp-dwellers like the big-headed paramegahadrids to speedy two-legged runners such as the flamboyant crested megacaudids. Then disaster struck (literally) at the end of the Oligocene in the form of the Haughton Impact and they entered the Neogene with just two out of six families.
The North American duckbills quickly made up for their losses in the Miocene, once again speciating into giants and midgets (although the small bipeds did not reappear). Their formidable chewing abilities made them particularly well suited to life in the spreading grasslands and, as sea-levels fell in the Pliocene, they launched fresh invasions into Eurasia and South America. However, dinosaurs marched both ways across the land bridges and new competitors and (perhaps) diseases led to a decline in the smaller neohadrosaur lineages. The Ice Ages of the Quaternary led to further extinctions as suitable habitats expanded and contracted with the glaciers.
As with their distant ungulapede cousins, the neohadrosaurs are united by peculiarities of the manus. With the loss of digit 5, the hand possesses only three fingers, each terminating in a large, hoof-like ungual that is comparatively larger than those of earlier hadrosaurs. In their Cretaceous ancestors, the weight-bearing digits were enclosed within a fleshy pad, but in the neohadrosaurs, the three manual hooves protrude from the flesh and play a greater role in supporting the animal and protecting the forefoot. This may be an relict of the neohadrosaurs' brief foray into bipedalism during the late Paleogene when the fingers were partially freed for defensive and manipulative purposes.
All neohadrosaurs appear to retain breeding habits similar to those of Cretaceous duckbills. 12 to 24 elongated oval eggs are deposited in a circular pit, incubation being provided with a cap of rotting vegetation. Megahadrines often form large communal nesting colonies whilst the stellasaurs keep their broods isolated and hidden.
MEGAHADRIDAE (Hmungos, galumphs, hipposaurs, and torgs)
The bulk of America's hadrosaurs belong to the recently erected Megahadridae. At a glance, these dinosaurs appear quite conservative when compared with their Mesozoic forebears, and for a long time were classified as living representatives of the Cretaceous-Eocene family Hadrosauridae. More detailed studies have revealed that these animals are far more removed from their Cretaceous ancestors than a cursory examination might suggest. Rather than representing a steady progression of the large Cretaceous-type hadrosaurines, it is now known that the earliest megahadrids in the Oligocene were medium-sized bipeds, similar to (but not immediately related to) the crested megacaudids. When the big paramegahadrids died out at the end of the Oligocene, the early Megahadridae quickly moved to seal the ecological gap, evolving into the large four-footed forms of today.
With the exception of the primitive galumphs, which can rear up on their hindlimbs, the megahadrids all obligate quadrupeds. The limbs, particularly the forelegs, have become thickened and pillar-like to better support the animals' weight. These graviportal adaptations give them a plodding, elephant-like gate unlike the more dainty motions made by stellasaurs and ungulapedes. All megahadrids tend to be rather slow moving and none can sprint. Thus they tend to rely more on size, a tightly knit herd structure, or aggression for protection (An adult bull hmungo is a far stronger and more solidly built animal than the largest theropod and can do some real damage to a careless tyrannosaur). The vertebrae have been strengthened although the ossified rods found in other duckbills have been reduced. Another unique feature (amongst ornithopods) is the possession of a large and muscular tongue that can quickly and efficiently transfer food from the beak to the cheek batteries.
Present day megahadrids can be divided into at least 2 subfamilies, the megahadrines and the hipposaurines.
MEGAHADRINAE (Hmungos and galumphs)
Megahadrines are large (none weigh under 1000kg), but not particularly diverse, with at least nine species distributed throughout North and Central America, eastern Eurasia and the northern half of South America. Most likely, these creatures evolved as riverside and swamp herbivores, where they evolved their distinctive short necks and long snouts. This cranial anatomy soon proved to be a useful adaptation not only for dredging up aquatic plants, but for grazing. Megahadrines also possess large and complex nasal chambers giving them a sharp sense of smell and a loudspeaker (and boy do we mean loud!) to keep in touch with other members of the herd or to intimidate enemies.
The two North American galumph species (genus Galumphia) live in the forests of southeastern North America, and look rather like the Mesozoic Edmontosaurus (though they are only distantly related). Despite their name, galumphs are actually quite agile, and can move with surprising speed when threatened, their latterally compressed bodies easily slipping between the trees. These forest browsers feed upon forest undergrowth, shrubs, and saplings, its batteries of diamond-shaped teeth mashing even the ubiquitous Deinorubus brambles into a digestible paste.
A galumph's physiology is very similar to that of its Mesozoic ancestors, with relatively weak hind legs, and a center of balance close to the hips. Galumphs never developed the enlarged neural arches over the shoulders (a common feature of many modern quadripedal herbivores) and will often rear onto thier hind legs to reach succulent branches.
With a mass of 5000 kilograms, the eastern galumph is small for a megahadrine, but it is the largest animal in the deciduous forests of eastern North America that are the creatures' home.
Three megahadrine species are to be found on South America. Two of these are southern outliers of primarily North American forms - a "dwarf" (7 metre long) morph of the greater hmungo and scattered populations of the eastern galumph - both of which are restricted to the north of the continent.(fig. 2) Zebra galumph, Galumphia bicolor (Central South America---Cloud forest)
The 5 metre-long zebra galumph is, however, an endemic species. These 4-meter pygmies live in the cloud forests of central South America.
The other group of megahadrines, the hmungos (sometimes alied with the shambala of northeast Eurasia) are larger than their forest cousins, dwelling as grazers on the great interior plains of North America. These elephantine herbivores are highly migratory, and, during the summer, hmungo herds habitualy pass only just south of the Arctic Circle.
The upper and lower bills of a hmungo's mouth function as the cutting blades of this living lawnmower. Grass is clipped off near the roots by the beak, and then slid back into the cheeks by means of an extremely long and muscular tongue. Batteries of diamond-shaped grinding teeth (a gift from the hmungos' hadrosaur ancestors) reduce the high-silica vegetable matter to a digestible paste, which is then passed into the crop for further digestion before finally entering the stomach. This peculiarly dinosaurian digestive process is far more efficient than any mammalian system (although Home-Earth's ruminants, with their multiple stomachs, come close) and so hmungos can grow much larger on a diet of grass than can any furry creature.
(fig. 3) A herd of greater humgos and palid singers and menaced by a threesome of pecos draks, Megahadrus titanus, Neostellasaurus pallidus, and Paraboreonychus horridus (central North America---Great Plains)
Greater hmungos (Megaharus titanus) are elephantine grazers, the culmination of the megahadrid radiation of giant grazers. Dwarfing the other herbivores of the plains, greater hmungos most closely resemble the African grassbags in their habits; they are biological vacuum-cleaners.
The greater hmungo may be found across the plains of central North America, the small, closely-knit herds migrating past the 60th parallel during the summer and the 30th in the winter. A non-migratory, dwarf subspecies of greater hmungo can even be found in northern South America.(fig. 4) Sludger or swamp hmungo, Megahadrus mississippiensis (southern North America and central America)
Hmungos mate for life, and roam about the grasslands in pairs or in groups of immediate family. The herds only collect during the spring (northward) migration, when the unmated bulls trumpet their challenges across the prairie, hoping to impress potential mates with the strength of their voices. Courting and mating take place during the move, and by the time the herds have reached their summer breeding grounds in northern Canada, their eggs are ready to be laid. Incubation is short, no more than four weeks, and the young are ready to walk within 14 days of hatching. In the North, the season's turn takes place soon after the hatching, and the hmungo calves have to grow up fast. Many are still wobbling on their feet when the herds begin their migration south, and it is at this time that the hmungo population is most vulnerable to predators. Draks hide in clumps of brush to ambush unwary juveniles, while striders pursue the herds' sick and aged population with lethal dedication.
Despite this periodic thinning of the herds, hmungos generally suffer little predation. A 15 meter-long, 6000kg bull hmungo is more than a match for any carnivore; even sabre-tryants tend to leave the giant herbivores alone. Because of the protection they offer by their presence, hmungo family groups often form the nucleus of much larger mutli-species herds composed of singers, viriosaurs, and therizinosaurs. Smaller species, such as the hawk-sized hmungo-swoops (Agilifuga rufa ) have become totally dependent upon the giant megahadrids and the insects they flush out of the grass.
An organism as large as a hmungo cannot exist without altering its environment. Over the millennia, the grasslands of North America have adapted to the constant grazing of the greater hmungo and its ilk, giving them a distinctly different feel from the relatively untouched prairies of our home timeline. Some prairie grasses are very fast-growing, almost visibly pushing skyward in the spring growing season, relying on their metabolic speed to outpace hmungo appetites. Other species tend to be shorter than on Home-Earth, offering a smaller surface to be gripped between lawnmower jaws. The blades and stalks of all these grasses are high in silicates, with slicing or sawing edges capable of cutting even a hmungo's leathery hide. Older hmungos may carry scars of grass-wounds on their snouts, but the giant herbivores seem not even to notice these defenses, scything through the grasslands as if the saw-toothed blades were not even there.
The hmungos probably do a great deal to preserve their environment, however. Were it not for these leviathans ripping the soil apart, trampling small trees and bushes, and cutting their swaths across the prairie, North America's great grasslands would be a fraction of their current size. In fact, America's seas of grass extends quite a bit farther than those of our own timeline.
Sludgers are the second largest species of megahadrid, frequenting the rivers, lakeshores, and bayous of southern North America and central America, towering over the little kranili as they scoop vegetable matter into their wide, flat-tipped maws.
Like their cousins, the greater hmungos, sludgers travel in small family groups with a single mated pair leading a bevy of children and siblings. When the faces of the young males flush with red and green mating colors, they leave the bevy to find females. Upon finding an attractive bride, the young male displays, not to her, but to her father, the bull of the bevy. During the March mating season, old bulls sometimes find themselves surrounded by suitors, each displaying madly.
The east-Asian shambla is unmistakably a megahadrid, and not related to the Eurasian/African ungulapeds. This old-style herbivore pre-date the ungulapeds, and represents a Miocene radiation of grass-eating hadrosaur. Shamblas' habits are poorly known and additional species may be awaiting discovery. Strangely, Asia shares no extant megahadrine genera with North America, although there was a significant fossil correspondence early in the Quaternary.
(fig. 5) Shambla, Belusaurus benseni (North-eastern and eastern-costal Eurasia)
HIPPOSAURINAE (Rawheads, torgs, and snufflelumps)(fig. 6) Rawhead, Hycephale longicaudus (Eastern-costal North America)With thirty species, the hipposaurs ("horse lizards" - an allusion to their large hooves and the horse-like whinnying produced by some species) can be found throughout the Americas south of the tundra. While producing a number of supertitans in the past, no living hipposaur comes close to rivaling the giant megahadrine hmungoes in size, but they are all big animals, ranging from 350 to 3500kg in weight.
While generally similar to their megahadrine cousins, a number of features distingusih the hipposaurs. They do not gather in massive herds like the hmungoes and, with the exception of the South American torgs, tend to avoid the open habitats, preferring more sheltered environments such as woodlands and swamp forests. While possessing large nasal cavities, the fleshy chambers are not as complex as those in the megahadrines, making the hipposaurs' vocalizations less complex, but no less loud.
The forelimbs are proportionally longer than those of megahadrines and share a greater burdern of bearing the animals' weight. The tail tends to be rather narrow and stubby, possibly because their function as balancing devices is no longer required for these front-heavy herbivores. Finally, while megahadrines are all "smooth-backed", many species of hipposaur possess dorsal ornamentation in the form of triangular osteoderms or elongated scales.
The most notable anatomical feature of the hipposaurs is the almost total loss of the network of ossified rods associated with the neural spines of all other duckbills (these struts are reduced in their megahadrines, but still present). The solid limbs have eliminated the need for these support structures and allowed the tail and torso to become more flexible, a bonus when moving between the tree trunks.
Although originating in North America during the Miocene, the loss of moist woodland habitats at the end of the last Ice Age have made the hipposaurs sparse and scattered on their original home continent. The eight or so hipposaurs tend to be rather smaller than their southern counterparts and their distribution is restricted.
The rawhead reaches a length of just under 6 metres and weighs in at 1.5 tonnes. Unusually gracile for a hipposaurine, it is considered to be the most primitive living representative of that subfamily, with less prominent graviportal features and an unusually long tail. Small rawhead herds dwell in the temperate deciduous forests on the east coast of North America.
Rawheads desperately need to build up reserves of fat during the summer and the long tail provides a large surface area for the buildup of apidose tissue to help see it through the winter. When the snows arrive, the herd huddles together in one spot to conserve energy and the animals spend their time listlessly chewing on twigs.(fig. 7) Greater torg, Epippiosaurus sinkkoneni (South-central South America)With the coming of spring, the gaunt rawheads browse ravenously and, with the breeding season imminent, develop the rosy-pink facial colours from which inspired their common name. Breeding leks are loud and violent spectacles as the males club each other with their thickened domed snouts.
It is in South America that today we find the full flowering of hipposaur diversity. With relatively little competition, the twenty-two Neotropical hipposaur species are the most common low-browsers and grazers on the continent. On the open plains to the south of the Amazon, they have produced the torgs, large grazers that echo their hmungo cousins in the North.
The torgs of South America are the only specialized grazers amongst the hipposaurines, and the 3.5 tonne greater torg is the largest and most widely distributed of these hadrosaurs. These creatures dwell in small, closely-knit herds from the Amazon basin south to Spec's pampas grasslands. Smaller than both pachamacs and k'z'ks, greater torgs are far more common than either of these giant herbivores, and can almost always be spotted grazing upon the pampas grasses. Like their North American cousins, the hmungos, greater torg herds are often associated with smaller animals, most notably the fuzz-butts that feed upon herbs uprooted by the hadrosaurs.
(fig. 8) Darwin's torg, Epippiosaurus darwini (Southern south America)
With a mass of about 3000 kg the darwin's torg is slightly smaller than the greater torg. These animals migrate across the patagonian pampas alone or in mated pairs. The female darwin's torg lays 3-5 eggs and takes care of her calves for about a year, protecting them from magnoraptor packs the occasional courageous errosaur.
(fig. 9) Snufflelump,Longicephaloides inexpectatus (Central south America---Amazon)
With its compact, heavy-set body, awkward plodding gait, beady-little eyes and extraordinary long, narrow bill, the snufflelump is about as weird as they come.
This solitary animal roots around on the forest floor, probing into the leaf litter with its schnozz in search of roots, tubers, fungi and fallen fruit. During times of flood, it wades in the shallows, consuming entire seedlings and small shrubs by plunging its beak into the soft mud to grasp the plant by the roots. Like the frill tusker and the spineback kentropod, this remarkable half-tonne hadrosaur is a secretive and poorly known denizen of the South America's tropical jungles.
(fig. 10) Head of snufflelump
STELLOSAURIDAE (singers)(fig. 11) Grasbuck, Gramesaurus americanus (central North America)
Singers represent the last remnant of the the once-great American diversity of small hadrosaurs. These dinosaurs formerly occupied all the small herbivore niches in North America, as well (the smallest known stellosaur, Microhadrus , likely massed less than 10 kg), but these forms have been largely pre-empted by the viriosaurs from the South and the dwarf therizinosaurs from the North. Additionally, a number of larger forms (over 500kg in weight) were around during the Pliocene and early Quaternary. They are (apparently) restricted to warm-temperate to tropical North America although the fossil evidence suggests that they once ranged from the Subarctic to Patagonia.
Today, the singers occupy most of the small-to-medium (from about 50 to 200 kg) herbivore niches in central North America. These creatures are most common in the great American prairies, but can be found in enclaves across the continent. Even as far north as the 60th parallel, the domain of the therizinosaurs, the summer sun brings vast herds of migratory herds of grasbucks, Stellosauridae's most nomadic species.
Fossil and morphological evidence suggests that the stellosaurines split off the main neohadrosaur line early in the Cenozoic, although they do not appear in the fossil record until the very end of the Oligocene. These dinosaurs are easily distinguished from their relatives, the megahadrids by the the bizarre construction of their respiratory passages, which resemble nothing so much as those of a bird. Stellosaurines, of course, do not possess the air sac system of their distant cousins, but their larynx (voice box) has evolved in startling convergence with the avian syrinx. With the aid of their modified vocal chords, stellosaurines can produce a wide range of bird-like calls that are easily differentiable from those of other hadrosauroids, which use their nasal passages rather than their voice boxes as resonating chambers.
The grasbuck (Gramesaurus americanus ) is the most common and well-known species of the singers. These selective grazers form small herds that migrate across the North American praries, often heradling the arrival of larger animals such as painted singers and hmungos.
A nomadic species, grasbuks migrate from southern North America as far north as the 60th parallel as the seasons change.
(fig. 12) Valley singer, Stellosaurus valensis
(southern coastal North America)
Equally at home in forests or the dry grasslands of the Sierra rain-shadow, the valley singer is ubiquitous across the southern portion of North America's west coast. Valley singers are isolated from other singer populations by the Rocky mountains, and so are often the only herbivores of any size in their environments (although some parts of their range overlap with the least hmungo). These fleet footed, graceful herbivores eat a variety of plant material, including such unpalatable of wood urchins and sagebrush.
Valley singers are not as social as grasbucks, but they do tend to gather in small herds of no more than a dozen individuals, and have no apparent hierarchy of power among adults. Valley singers communicate within and between herds with their voices, which, due to their stellosaurid syrinxes, are quite variable. Recordings of singer 'conversations' within a single herd in the San Joachin Valley have been made, and some last for hours, but what meaning these vocalizations convey is unknown.
The starry singer is not a prairie
species, but inhabits the deep deciduous hardwood forests of the
southern part of North America. As the creature is a forest dweller,
it lacks the flat tipped beak of the hmungos , having evolved
to feed upon low flowering bushes. They can occasionally mix with hmungo
and other singer herds.
This singer's skin, patterned with dark colors and light bands, helps it to camouflage from potential predators, its disruptive pattern will splendidly blend them with the surroundings. This dinosaur exhibits distinct sexual dimorphism, males having a much more heavily spotted skin and a thicker nose bump and being rather smaller than the females. Males also adopt a black mask during the courtship period.
The females often form small groups (reports telling of 4 females and respective calves if any) with only one dominant adult male (other adult and juvenile males with no harem usually go solitary or in pairs).
The singer's specific name indicates a curious characteristic of this dinosaur. Like other stellosaurs, starry singers make use of their bird-like vocal organs to communicate with each other. Males have a rich repertoire, which is only used during the breeding season. Each "song" has a specific purpose. One is used by a dominant male to keep other males at distance, one other may be used to find a lost element of the herd, and so on.
This dinosaur cannot be confused with any other in the forest, because of its bright stripes of spots which give the dinosaur its name. Several pattern variants are known.
Walking through a singer-inhabited forest, one can easily miss the animals, superbly camouflaged as they are, but one will probably hear their beautiful singing.
(fig. 13) Starry singer,Stellasaurus communicatorius (southern North America)
(fig. 14) Painted singer, Neostellasaurus pictus (central and southern North America)
Another member of the singer complex, the painted singer is closely related to the starry singer . This species primarily dwells in the prairie and in outer ridges or forests, usually along the course of rivers.
Thought not as vocally talented as the starry singer, this species is also strongly vocal, music consisting in metallic clicks and high pitched sounds, and an occasional thunder like roar used by the male to alert the herd of adjacent dangers.
In opposition to all other stellosaurid species,
which only form small herds, pale singers gather into gigantic collections,
often forming mixed herds with hmungos and other hadrosaurid
species in search for tall grasses and flowering bushes in spring and
summer. 
A half-ton alpha bull leads the herd, commanding the respect of the other male members. These bulls often engage in ritualized dominance fights, where they flash the striking pale dots along their flanks. The two-meters long, 250 Kg, females are whitish brown in color.
(fig. 15) Pale singer, Neostellasaurus pallidus (central North America---Great planes)
Pale singers (and their cousins, the painted singers) are remarkable for their extreme sexual dimorphism, expressed as brilliant "dominance colors" in a herd's alpha male. A year after being born, young males rapidly increase in size, and the bulls will attain their adult masses at 5 years, at which point they are sexually mature. Cows, however, reach adulthood at 3 years of age, although they rarely lay eggs before their fifth year.
Upon reaching sexual maturity, bulls begin to engage in dominance battles, the losers forming small fraternal herds and parting from the main herd body. Most often, the only males in a large herd are subadults and a single alpha bull, who is constantly challenged by younger suitors. The resident bull almost always wins these battles, but even these big bulls will get old (thought they may reach over 100 years) and younger males may get lucky.
If a young bull manages to defeat a resident alpha, its body changes suddenly and in a few weeks into its "dominance coloration". While of pale brown coloration when adolescent, a new alpha bull's hide will darken quickly upon his rise to power. After a few weeks, five buff splashes appear on both frontal flanks, his cheeks turn into rusty red, the frontal part and forehead become black, the tip of the muzzle and the chin pale to white. The hump increases in size and the neck skin dewlap turns scarlet on the upper fringe. A full adult male pallid singer is a truly spectacular sight.....now imagining two bulls fighting.
The perennial question as to the existence of a stellasaurid in the highland tropical mist forests of South America remains a controversial topic amongst specbiologists. No human has ever set eyes upon a living South American singer although fossils of several large Early Quaternary forms are known from Patagonia. A haunting, flute-like song has been recorded on several occasions near Cerro Neblina, drifting through the early morning highland mists. The creator of these sounds has never been seen but the song shares sequential similarities to that of the the North American painted singer. Casts and photographs of small quadrupedal ornithopod tracks have also been produced from the region which do not seem to belong to any known viriosaur. Many authorities remains skeptical and the capture of this animal on film or in the flesh has become a sort of holy grail for specryptozoologists.
Daniel Bensen, Brian Choo, João Boto , and Ville Sinkkonen
,=G. hebes
,=Galumphia=|
| `=G. bicolor
,=Megahadrinae=|
| | ,=M. titanus
| | ,=Megahadrus=|
| | | `=M. mississippiensis
| `=|
| `=Belusaurus benseni
,=Megahadridae=|
| | ,=Hycephale longicaudus
| `=Hipposaurinae=|
| | ,=E. sinkkoneni
| | ,=Epippiosaurus=|
| | | `=E. darwini
| `=|
| `=Longicephaloides inexpectatus
Neohadrosauia=|
| ,=†Microhadrus
`=Stellosauridae=|
| ,=Gramesaurus americanus (Grasbuck)
`=|
| ,=S. communicatorius (Starry singer)
| ,=Stellasaurus=|
| | `=S. valensis (Valley singer)
`=|
| ,=N. pictus (Painted singer)
`=Neostellasaurus=|
`=N. pallidus (Pale singer)
