Although their ancestors seem to have been fairly ordinary looking generalist ornithopods, Laurasiornithopoda of today consist of three highly derived clades, each adapted to a very different lifestyle. The jackalopes (Struthiodactylidae) have remained most true to their ancestors' lifestyle, being small fleet-footed grazers or low-browsers although they've taken the running lifestyle to its extremes, while the vanguards (Vanguardidae) have become huge plodding armoured tanks that echo the nodosaurs and ankylosaurs of old, though several species of the both nodosaurs and ankylosaurs do survive in the Spec World. Even stranger still are the duckongs (Laticanatidae) which have taken to a new element, paddling in rivers and oceans like weird duck-manatee-hybrids, while being clumsy and near helpless when they venture on land out of the necessity to lay their eggs.
The Earliest fossils of animals with recognizably struthiodactylid characters appear in the fossil record in the Early Eocene, but these animals had yet to change much from their Cretaceous ancestors. By Middle Oligocene they had evolved into forms like Protostruthiopes, that had already clearly shortened arms and elongated metatarsals. Pedal digit V was completely lost and digit I seems to have been greatly reduced. There was no sign of the typical crest, but otherwise this animal had clear resemblance to some present day forest jackalopes. Some semi-cryptic Southeast Asian forest jackalopes have been claimed to be surviving protostruthiopods, although they more probably represent a primitive miostruthiodactylid lineage. However, it is commonly believed that the ancestry the Jackalopes can be traced back to Thescelosaurus.
The Miocene brought about a great evolutionary spurt in jackalopes as they began to adapt to the new grassland environment. It is believed that at this point true jackalopes diverged from some of the most primitive Asian forest jackalopes (the blanket term forest jackalope is misleading, as the group consists of different separate clades, some further away from Old World jackalopes than those are from American jackalopes.) The feet of Miostruthiodactylus had elongated metatarsals, it had lost pedal digit I and digit III was clearly longer and more robust than the other weight bearing toes, which all bore hoof-like claws. It also had a simple arching laterally flattened cranial crest. Miostruthiodactylus has been found in both Eurasian and North American deposits, and it is thought to be a likely common ancestor of Struthiodactylus and Hippodactylus (the American jackalope). While on the subject of the Eurasia and the Oligocene epoch, some Specreasechers believe that the Eurolophs are considered a part of the Laurasiornthiopodia family. However, this is still under debate.
In the Old World jackalopes flooded the African continent in various forms, filling the small grazer and browser niches in both in forests and the newly appeared savannas. The savanna dwelling forms seem to have given rise to modern gazelle-like struthiodactylids with their characteristic long legs, three-toed feet, shortened torsos and reduced forelimbs. The forest jackalopes (Parastruthiodactylidae) of Africa seem to be descended from early grassland or forest edge dwelling forms, but lack certain advanced dental features, which struthiodactylids and hippodactylids seem to have evolved convergently to feed on grasses, as well as possessing functional if very short arms with two or three clawed digits.
Besides certain Asian taxa, all present day jackalopes sport cranial crests of some kind, which in American jackalopes have evolved into a antler-like laterally forked crown, but tend to be less flamboyant in Old World jackalopes, especially forest-dwelling froms. Although horn-like in appearance, these ceratin-covered crests seem not to be used in intraspecific combat or defense, probably due to their lightweight brittle structure, but serve mainly as sexual ornaments. In some species the female's crest is almost absent, but in many Struthiodactylus species females have crests comparable to those of young adult males. Possibly the shape and coloration of the crest serve identification purposes within the herd.
Jackalopes (genus Struthiodactylus) are small (15 - 40 kg) and fleet-footed ornithopods that roughly the niche of HE's gazelles. Thought to have evolved from antarctornithopods of possibly Indian origin, these animals are the fastest runners in the Spec Old World. Their adaptations to conserve water and survive night-time freezes has given them the upper hand in arid habitats, but elsewhere they have lost the competition to other ornithiscians and oviraptorosaurs. Three genera consisting of a total 9 species of jackalopes have been identified in Africa, India and the Middle east, where they inhabit dry savannas and deserts.
STRUTHIODACTYLIAE (Old World Jackalopes)
The jackalopes are probably the most famous Spec ornithischians. The clade is wondrous, with their complete devotion to bipedality. Jackalopes have a very complex pelvis with the "puschium" and boot possessing quite a few ligament and muscular attachments not seen on any other dinosaur. They also have exquisitely developed ear canals, both for sensitive hearing and to maintain a sense of balance that puts most other bipedal dinosaurs to shame. Jackalopes have been observed casually balanced on slippery, diagonally angled epiphyte covered logs that the same observers slide right off of trying to scale. Like the errosaurs and abelisaurids who are among their most feared predators, jackalopes have tiny, often pointed stubs for arms.
Jackalopes have the most extensively pneumatic bones of any non saurischian tetrapod. These air sacs connect to the trachea however; they do not directly contribute to respiration. The diaphragm of jackalopes is directly connected to both femur muscles. When jackalopes run, they shift over to a macropod mimicking breathing system; resulting in an intake of breath with every leg push. This allows them to supercharge their bodies with oxygen; coupled with their unusual leg structure, plains jackalopes can propel themselves at velocities akin to HE pronghorns with ease. However, although tendons and muscles can handle the load, it still takes jackalopes some time to reach optimum cruising speeds.
The Old World jackalopes are far more diverse and numerous than their American relatives. It is estimated that some 120 to 160 species range throughout the Paleotropics. Although jackalopes were originally creatures of the plains, during the Miocene, the first struthiodactylines show up in miombo woodlands. By the Pliocene, the tropical forests of Africa and Asia were becoming a hotbed of jackalope evolution. This jungle radiation has also resulted in a turnover for plains and desert jackalopes, as many rainforest jackalopes expanded outward into those biomes.
Arabian Jackalope (Struthiodactylus arabicus)
The Arabian jackalope (Struthiodactylus arabicus) is a modest-sized jackalope, weighing around 20-35 kilograms. This species is restricted to the Arabian peninsula. Arabian jackalopes feed mostly on grasses, but may also feed on leaves and scrubs. Arabian jackalopes rarely drink, mainly surviving on the moisture they get from plants. They are the only jackalope species with dinofuzz .
Golden Jackalope (Struthiodactylus chrysafenios)
The golden jackalope (Struthiodactylus chrysafenios) is the largest living jackalope species in Specworld, with proportionally longest legs of any jackalope and weighing up to 100 kilograms. It is found in the dry scrubland of Africa south of the Sahara desert. Its name comes of its coloration that is a combination of white, gold and dark brown. The crest is striped in black and dark orange.
CERVOCEPHALINAE (Forest jackalopes, Muntjackalopes, Rusabeluas)
This clade consists of the basal struthiodactylids, basically equivalent to the Asian deer species and african forest antelope in niche partitioning.
Malayan Muntjackalope (Sauromuntjac malayanus)
The Malayan muntjackalope (Sauromuntjac malayanus), a 1.5-metre-long browser of southeast Asian forests, most notably in places like Indonesia, Thailand and Myanmar. Numerous species of Sauromuntjac can be found all over mainland Asia and the Indonesian archipelago, all of them similar in most respects except horn shape and colouration. This species is mainly mottled red-brown and dark green, with black bands on its tail. Most species make a deep groan to proclaim their territory.
Two-Horned Rusabelua (Rusabelua duocornis)
The two-horned rusalope (Rusabelua duocornis) found over most of mainland southern Asia, in marshland, scrub, woodland and rainforest. Like all members of Rusabelua (numerous species over mainland southern Asia and the Indonesian archipelago) it can run very fast through the forest undergrowth. At 3.5 m in length, this species fits in the upper level of the size range for rusabeluas; the smallest, the five-horned Indian rusabelua (Rusabelua indicus), is only 2 m long, and the largest, the Bornean rusa-beast (Rusacephalus borneensis), gets to a length of 4 m. The species shown here is most often a lime green on top, speckled with red-brown, with a yellow-white underbelly. The rusalopes make a beautiful trilling whistle that is a comfort in the hostile environment of Indonesia's jungle.
Red Duke (Casauriodes agilis)
The 1 m long red duke (Casauriodes agilis) is a common sight in the dry forests of Africa. Being a browser, it is quite common, and can get up to a good clip as it runs through the scrub. Other species are found all over Africa; for example, the 1.5 m blackback duke (Casauriodes nigrodorsum) is a denizen of the Congo rainforest, as is the spotted duke (Casauriodes pardalis), which is only 1 m in length. Most species of Casauriodes have white skin on their undersides. The 2 m long savanna duikerlope (Casauriodes bicolor), coloured a handsome gold colour with a white underbelly, is an exception to the rule. It is a small grazer that is very common on the east African savannas. Most varieties make a doglike high-pitched bark.
Blackback Duke (Casauriodes nigrodorsum)
Both the blackback and the spotted dukes C. pardalis are .5 to 1.5 meters in length. These critters can be found along the western flanks of the Ruwenzori Mountains. The blackback duke often can be seen soaking up the early morning sun after especially chilly nights. Monogamous pairs dig out dry burrows on the driest sides of mountain flanks. The burrows are lined with mosses and dry grasses to keep both the mated pair and their young dry and warm during the coldest nights.
Bristlehorn Scrub-Jackalope (Nanocasauriodes ornatus)
A native to Africa's Sahel zone and with a name which is not to be confused with the massive afrohadrosaur, the bristlehorn scrub-jackalope (Nanocasauriodes ornatus) is a member of a clade of denizens of thorn-scrub savanna. They possess brightly coloured faces and branching single horns. Only the weight of a large rabbit, the bristlehorn scrub-jackalope is a small browser common in the Sahel. It makes a piping trill when agitated or proclaiming territory.
Loper (Antillobelua saurotigris)
The 3 m long Loper (Antilobelua saurotigris) is an elusive browser of the Congo rainforest, most commonly seen on "hoser" highways and in other clearings at dawn and dusk, feeding on soft herbage and leaves. A stunning emerald green with striking maroon spots and stripes, it blends in perfectly with the jungle undergrowth. It makes a startling barking grunt as it forages.
HIPPODACTYLIAE (NEW WORLD JACKALOPES)
American Jackalope (Hippodactylus americanus)After the Old World Jackalopes, it's time to move on to the other branch of the struthiopod family tree. The American jackalope (Hippodactylus americanus). This small and speedy dinosaur has taken the pedal adaptations even further, having functionally only one toe left in its foot. This is even more extreme than the condition seen in ostriches, and proved controversial, as some Spec members didn't think a one-toed creature could work. Perhaps they were right, but I'd like to see someone prove that a one-toed quadraped would work either in a world with no horses. It would be hard to build a case on artiodactlyans and kangaroos, that's for sure. Besides the different feet of hippodactylids, they differ from their struthiodactylid cousins in having branching crest that vaguely resembles a pair of antlers. American jackalopes are also proficient leapers, because these small dinosaurs often have to venture into grass taller than themselves, where jumping up is the only way to look around. Jumping up while running is also a way to make themselves a harder target to American khinners.
Florida Jackassalope (Hippodactylus floridius)
This Florida jackassalope races through the central Florida scrub at a top speed of nearly 60 mph. Males have a harem of some 3 to 6 females that both retreat to bastardsloth and meiolanid burrows during the January/February freezing season. These 7 kilo critters begin laying eggs within sheltered burrows by April. Late June has the chicks piping out of their eggs. The chicks form a crèche largely isolated from their parents until October.
Jacklizard (Hippodactylus vulgaris)
Jacklizards are widespread throughout the limited range of New World jackassalopes. Although many successive glaciers have resulted in isolated populations developing unique characteristics; however, the current inter-glacial has allowed much interbreeding north of Central America, resulting in an relatively homogenized species.
Llanos Jackassalope (Hippodactylus venezueliasis)
The llanos jackassalope is the largest of the hippodactylids found in the region. Adult bucks reach nearly 120 kilos. These jackassalopes graze heartily through the end of the wet season. They mate with spectacular displays by both sexes. When a buck chooses up to three does for breeding, they secrete themselves within scrub and form a large mound to lay up to 80 eggs in. From this clutch, about 50 chicks hatch out after three months. The babies retreat into dense scrub for nearly six months before joining their parents in the main herd.
Mexican Jackassalope (Hippodactylus grandis)
This is the most widespread species of New World jackassalope, found from southern Mexico tropical dry forests north into the Sonora and Baja deserts and the central Californian valley. Mexican jackassalopes are quite scrappy, they can tolerate very cold night time temperatures as long as they can retreat to abandoned mammalian or vanguard burrows. Mexican jackalopes frequently enlarge bastardsloth and diggadum burrows for entire herds of nearly 20 members. Even though the jackalopes themselves are nearly 90 kilos, their benefactors mass hardly less than a third at times.
These jackalopes depend upon the warm burrows during the cold winter nights. Freezing temperatures don't affect adults too much; but the eggs and newly hatched spring chicks must be protected from the cold by shivering and rotted vegetation. Late May brings all the members of the flock out in full force. The November mast has all the fatten jackalopes chasing out vanguards and bastardsloth from exploratory winter burrows. Mexican jackalopes store some stolen foodstuffs as well as layer up some fat. However, they primarily use the burrows for night time shelter and browse during the warmth of the day.
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