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Article: Novel data on aetosaur (Archosauria, Pseudosuchia) osteoderm microanatomy and histology: palaeobiological implications

Palaeontology Cover Image - Volume 61 Part 5
Publication: Palaeontology
Volume: 61
Part: 5
Publication Date: September 2018
Page(s): 721 745
Author(s): Ignacio A. Cerda, Julia B. Desojo, and Torsten M. Scheyer
Addition Information

How to Cite

CERDA, I.A., DESOJO, J.B., SCHEYER, T.M. 2018. Novel data on aetosaur (Archosauria, Pseudosuchia) osteoderm microanatomy and histology: palaeobiological implications. Palaeontology, 61, 5, 721-745. DOI: /doi/10.1111/pala.12363

Author Information

  • Ignacio A. Cerda - CONICET‐Instituto de Investigación en Paleobiología y Geología Museo Carlos Ameghino Universidad Nacional de Río Negro Belgrano 1700, Paraje Pichi Ruca (predio Marabunta) 8300 Cipolletti Río Negro Argentina
  • Julia B. Desojo - División Paleontología de Vertebrados Museo de La Plata CONICET Paseo del Bosque s/no B1900FWA La Plata Argentina
  • Torsten M. Scheyer - Paläontologisches Institut und Museum Universität Zürich Karl Schmid‐Strasse 4 8006 Zürich Switzerland

Publication History

  • Issue published online: 03 August 2018
  • Manuscript Accepted: 12 February 2018
  • Manuscript Received: 06 September 2017

Funded By

Fondo para la Investigación Científica y Tecnológica. Grant Numbers: PICT 2012‐925, PICT 2014‐0609
Swiss National Science Foundation. Grant Numbers: 31003A‐149506, 205321‐162775

Online Version Hosted By

Wiley Online Library
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One of the most striking features of aetosaurs is the possession of an extensive bony armour composed of dorsal, ventral and appendicular osteoderms. With the purpose of establishing the main histological changes during ontogeny and the degree of histological variation within the armour, we analysed the bone histology of dorsal (paramedian and lateral), ventral and appendicular osteoderms from different taxa from the Late Triassic of South America, including Aetosauroides scagliai, Aetobarbakinoides brasiliensis and Neoaetosauroides engaeus. Histological data support an intramembranous origin for osteoderms. Nevertheless, evidence for metaplastic ossification (i.e. structural fibres) at advanced ontogenetic stages, in at least some elements, is also present. A variant type of parallel fibred bone, which we have named ‘crossed parallel fibred bone’, is characterized for aetosaurs. In this pseudosuchian group, osteoderms exhibit very important microstructural changes during ontogeny, which can be useful for determining ontogenetic stages from isolated elements. Histological data suggest a relatively early onset of sexual maturity among aetosaurs. Microanatomical analysis from different taxa reveal that having high values of compactness is the plesiomorphic condition for Aetosauria. The notably increased compactness of the osteoderms does not appear to be related to size, ontogeny, sex or reproductive status of the individuals. Although a high degree of compactness of osteoderms and other bones has been considered as evidence for an aquatic lifestyle in vertebrates, such an inference contradicts the current concept of a fully terrestrial lifestyle in aetosaurs.

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