Among the plant-eating dinosaurs, the hadrosaurs or duckbills must rank as one of the all-time great success stories. Appearing midway through the Cretaceous, they rapidly diversified and spread across the globe. Spared from annihilation at the close of the Mesozoic, they continued to spread and diversify past what would have been the K/T boundary, producing a host of weird forms during the Palaeogene. Despite suffering a number of setbacks as the Cenozoic progressed, they remain today as the dominant terrestrial megaherbivores on Spec and are found on all warm landmasses except Australasia, Antarctica and Madagascar.

Hadrosaurs are highly derived ornithopods notable for their expanded beak (giving the characteristic "duckbilled" appearance), a reduction in the number of wrist bones and the loss of the first digit on the forefoot. The dentition is extraordinary and consists of up to 1600 tiny cheek-teeth wedged together in tight batteries. These teeth are being continually replenished, giving the hadrosaur an effective grinding surface throughout its life. The lower jaw can be moved fore-and-aft, and the upper jaws can swing out to the sides as in most other ornithopods, which makes the duckbills' tooth batteries supremely efficient processors of plant matter.

The enigmatic chuanlong (Allohadros magnificus) is a recently-discovered herbivore that lives deep within the forests of eastern Asia. Known only from a single skin and observations gleaned from a Specbiologist from a boat on the Yangzi.

The chuanlong was at first assumed to be a formosicorn ungulapede, but examination of the head (unfortunately, the nature of the tell-tale hooves were not recorded) leads one to believe that this dinosaur belong to the more basal hadrosauroid clan. In fact, the chuanlong bears a striking resemblance to the shamblas and hmungos of Eurasia and North America.

Perhaps this cryptic herbivore is the descendant of the Miocene migration that brought the shambla to the Old World. If so, the chuanlong is descended from a hitherto unknown branch of the hadrosauroid tree, for it exhibits a number of unique features, such as an inflatable nasal pouch and a series of bony scutes along its back.

Without better specimens, it is impossible to know whether the chuanlong is an aberrant neohadrosaur, an aberrant ungulaped, or something else altogether.

(fig. 1) Chuanlong,Allohadros magnificus (South China)

 

NEOHADROSAURIA (Hmungos, galumphs, torgs, snufflelumps and singers)

Hadrosauridae consisted of two major groups, the flat-headed Hadrosaurinae and the hollow-crested Lambeosaurinae. The latter died out sometime near the end of the Eocene (except in Asia where †Sauropodimimus hung on through the Oligocene). The hadrosaurines survived, however, and as the global forest fragmented, these dinosaurs radiated ispread onto the grasslands and became grazers. The first of these animals had evolved in the forests as small creatures superficially similar to today's singers, but when the forests began to recede, some left their traditional modes of life. When the Miocene arrived and grasses spread across the continents of Earth, these grazing hadrosaurids began their golden age. The large grazing neohadrosaurs have changed little since this time, and are still the largest herbivores in North America (although in Eurasia they have been largely replaced by ungulapedes).

UNGULAPEDIA (Palaeungulapedes, saurolopes, cirafs, hornmeisters, and formosicorns)

With about 150 species worldwide, the ungulaped hadrosaurs are a major herbivore clade of the Old World. Ungulapeds are found throughout Africa and the warmer parts of Asia. Their origins are unclear, but some evidence ties them to Telmatosaurus from the end-Cretaceous of Europe, one of the minor groups of Hadrosauridae.

                                               ,=NEOHADROSAURIA
                               ,=Hadrosaurinae=|
               ,=Euhadrosauria=|               `?~Allohadros magnificus (Chuanlong)
               |               |
               |               `=†Lambeosaurinae=†Sauropodimimus
=Hadrosauridae=|
               |
               | ,=†Telmatosaurus
               `=|
                 `=UNGULAPEDIA

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