Aetosauria

From Tokaia

Aetosaurs were crurotarsian reptiles that resembled large armoured iguanas or herbivorous dinosaurs (specially stegosaurs and nodosaurs), although their closest modern relatives are crocodiles.

[edit] Evolutionary History

Like all crurotarsian groups, aetosaurs evolved during the Triassic period, and were among the major herbivore groups, alongside dicynodonts, rhynchosaurs and herbivore dinosaurs. Eventually, the later became more diverse and outcompeted them.

However, in Terra Alternativa, dinosaurs never evolved, and crurotarsians remained in a dominant position. Without the evolution of herbivore dinosaurs, both aetosaurs and dicynodonts became the dominant plant eating tetrapods. Unlike other crurotarsians, like rauisuchians, aetosaurs never became very diverse in terms of body designs, presumably because of their specialization to a slow herbivore lifestyle (pretty much like our world's armoured dinosaurs); however, this didn't prevented their success, as they were present in all continents, neither their variation in sizes: the smaller species were as big as alligators, while the largest competed with sauropods in terms of body weight and length (although not in height).

The golden age of these reptiles was the Jurassic period, and at least 15 genera are known from that era; however, with the arrival of the Cretaceous period, they declined very much, due to changes in vegetation and climate, and later from competition with herbivore crocodiles. By the end of this period, only a single genus, Daragonosaurus, survived in the southern continents, before it was exterminated during the K-T event.

[edit] See Also

Aetosauria on wikipedia