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Description
Curiously, medium sized herbivorous dinosaurs were very rare in Early and Middle Oligocene Asia. This arid environment was a place of extremes: a land of giants and dwarves. On the one hand, massive Titanosaurs were widespread and on the other a diversity of small Ornithischians were present as well. Hadrosaurs and Ceratopsids, previously a mainstay of Asia’s Eocene forests, fell at the Oligocene boundary, with their replacement not completed until the end of the period; although the Ankylotarsiiforms were gradually moving in this direction. These derived, flat headed Pachycephalosaur descendants originated in the Middle Eocene of Asia and increasingly showed adaptations for browsing and grazing on tough vegetation. While rare and marginal during the Eocene, never exceeding 2m in length, the extinction of Hadrosaurs across most of Asia allowed them a chance to diversify. And diversify they did. By the end of the Oligocene, large graviportal forms with chewing batteries of teeth had emerged, sporting all kinds of bizarre cranial horns and bosses. However, during the earlier stages of the period, most were small, speedy bipeds.

Tsaganodon was a representative of the Dorsodontid family, the smallest and most basal of the Ankylotarsiiformes. Although once very common across Eurasia and Africa during the Oligocene and Miocene, they declined severely during the Pliocene before eventually dying out by the Late Pliocene. T. constans itself was a 2m browser with a high tooth count and strong jaw muscles for chewing tough desert vegetation. Its later, more derived relatives would build on these traits, eventually evolving full batteries of chopping teeth for grazing on grasses. In modern times, Ankylotarsiiformes are found on all continents except for Australia and Antarctica, being Alter Earth's premier group of grazing herbivores akin to the Artiodactyls of Our Earth.

Description
Curiously, medium sized herbivorous dinosaurs were very rare in Early and Middle Oligocene Asia. This arid environment was a place of extremes: a land of giants and dwarves. On the one hand, massive Titanosaurs were widespread and on the other a diversity of small Ornithischians were present as well. Hadrosaurs and Ceratopsids, previously a mainstay of Asia’s Eocene forests, fell at the Oligocene boundary, with their replacement not completed until the end of the period; although the Ankylotarsiiforms were gradually moving in this direction. These derived, flat headed Pachycephalosaur descendants originated in the Middle Eocene of Asia and increasingly showed adaptations for browsing and grazing on tough vegetation. While rare and marginal during the Eocene, never exceeding 2m in length, the extinction of Hadrosaurs across most of Asia allowed them a chance to diversify. And diversify they did. By the end of the Oligocene, large graviportal forms with chewing batteries of teeth had emerged, sporting all kinds of bizarre cranial horns and bosses. However, during the earlier stages of the period, most were small, speedy bipeds.

Tsaganodon was a representative of the Dorsodontid family, the smallest and most basal of the Ankylotarsiiformes. Although once very common across Eurasia and Africa during the Oligocene and Miocene, they declined severely during the Pliocene before eventually dying out by the Late Pliocene. T. constans itself was a 2m browser with a high tooth count and strong jaw muscles for chewing tough desert vegetation. Its later, more derived relatives would build on these traits, eventually evolving full batteries of chopping teeth for grazing on grasses. In modern times, Ankylotarsiiformes are found on all continents except for Australia and Antarctica, being Alter Earth's premier group of grazing herbivores akin to the Artiodactyls of Our Earth.