Evolution of the temporal skull region

 

 

The temporal region describes the area between the orbits and occiput in the tetrapod skull. While it was ancestrally fully covered by dermal bone, many later tetrapods distinctly reduced their dermal armor in this region, often forming different sets of temporal openings like fenestrae or emarginations. Especially in amniotes (mammals, birds, reptiles) the configuration of these openings has been traditionally argued to be phylogenetically informative; hence, inspiring the naming of several taxa like Synapsida, Diapsida, or Anapsida.

 

However, new fossil finds, genetics, and large-scaled phylogenetic analyses raised doubts on the phylogenetic value of such openings. Instead, they may be responses to functional demands caused by the arrangement of the jaw musculature, cranial kinesis, or developmental strategy.

 

In this project we review the research history on the temporal skull region. Additionally, we analyze the evolutionary causes for the formation of temporal openings, especially in context of their initial evolution in early amniotes

 

This project is conducted as part of my doctoral thesis at the SHEP Tübingen in the lab of Prof. Dr. Madelaine Böhme, supervised by PD Dr. Ingmar Werneburg in collaboration with Yannick Pommery, Dr. David Ford, Dr. Neil Brocklehurst, and Prof. Dr. Daisuke Koyabu.

Skull of extant tuatara (Sphenodon punctatus) with two pairs of temporal fenestrae (red).

The early reptile Captorhinus aguti from the Permian of the USA, a model organism used for this project. Artist: Markus Bühler.


Related publications:

  • Abel, P. & Werneburg, I. (2021). Morphology of the temporal skull region in tetrapods: research history, functional explanations, and a new comprehensive classification scheme. Biological Reviews 96 (5): 2229–2257. doi: 10.1111/brv.12751
  • Abel, P., Koyabu, D. & Werneburg, I. (2019). Evolution of the temporal region in the early amniote skull. Paleo & Life Abstracts of the 90th Annual Meeting of the Paläontologische Gesellschaft, Munich 2019.
  • Abel, P., Pommery, Y., Ford, D.P., Koyabu, D. & Werneburg, I. (2021). Sutures and skull mechanics in the ‘anapsid’ Captorhinus aguti – what are their implications for early amniote evolution? XVIII Conference of the European Association of Vertebrate Palaeontologists: 19. https://sites.google.com/view/eavp2021/abstract-book.
  • Abel, P., Pommery, Y., Ford, D.P., Koyabu, D. & Werneburg, I. (2022a). Skull sutures and cranial mechanics in the Permian reptile Captorhinus aguti and the evolution of the temporal region in early amniotes. Frontiers in Ecology and Evolution 10: 841784. doi: 10.3389/fevo.2022.841784
  • Abel, P., Pommery, Y., Ford, D.P., Koyabu, D. & Werneburg, I. (2022b). 3D models related to the publication: Skull sutures and cranial mechanics in the Permian reptile Captorhinus aguti and the evolution of the temporal region in early amniotes. MorphoMuseuM 8:167. doi: 10.18563/journal.m3.167
  • Werneburg, I. and Abel, P. (2022). Modelling skull network integrity at the dawn of amniote diversification with considerations on functional morphology and fossil jaw muscle reconstructions. Frontiers in Ecology and Evolution 9: 799637. doi: 10.3389/fevo.2021.799637