Before Ankylosaurs, There Were Aetosaurs

Dr. Andrew Heckert (Appalachian State University) discusses how aetosaur discoveries from the last four decades have given us new insights into these animals. During the Triassic Period, before ankylosaurs appeared, aetosaurs were the evolutionary prototype of the heavily armoured animals. These “crocodile-line” reptiles are known from late Triassic rocks from across much of Pangaea . Like ankylosaurs, aetosaurs were covered in armour, with hundreds of overlapping osteoderms arranged in two columns on the back and sides of the animal. Most aetosaurs had additional armour on the underside of the body. Adult aetosaurs were typically 1.5 – 2.5 metres long, but exceptionally large individuals may have reached six metres. Many famous early palaeontologists worked on aetosaurs at some point in their careers, but these animals have remained relatively obscure for 150 years. Scientific understanding of aetosaur palaeobiology remains in its infancy, and details of their diet, origin and development, locomotion, and metabolism remain elusive. Largely considered herbivorous, it appears that some aetosaurs may have been insectivorous. Histological studies often indicate slow growth, with adult specimens older than 20 years old. Thumbnail photo credit: Appalachian State University Commercial Photography Class, Spring, 2018