, Volume 90, Issue 10, pp 473–476

Early loss and multiple return of the lower temporal arcade in diapsid reptiles

Short Communication


The temporal arches of diapsid reptiles have received attention for several decades. In particular, it has been observed that the lower temporal bar at the ventral margin of the cheek is frequently reduced due to the absence of a contact between jugal and quadratojugal. The loss of the arcade was formerly considered to be of high systematic value, but is now often interpreted as being autapomorphic for the respective taxon, and the presence of both arcades is generally regarded as a plesiomorphic feature. Here I show, based on a cladistic analysis as well as on further anatomical evidence, that the lower temporal arcade was lost only once in diapsid evolution, and that the presence of the arch in "higher" diapsids is secondary, which is indicated by the different ratio between jugal and quadratojugal as well as by ontogeny. This result also sheds new light on the understanding of the cheek configuration of enigmatic taxa such as ichthyosaurs and turtles.

Supplementary material

S1 Character list of the phylogenetic analysis

Muller_S1.pdf (60 kb)
(PDF 60 KB)

S2 Data matrix of the phylogenetic analysis

Muller_S2.pdf (848 kb)
(PDF 849 KB)

Copyright information

© Springer-Verlag 2003

Authors and Affiliations

  1. 1.Department of BiologyUniversity of Toronto at MississaugaMississaugaCanada

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