First Phytosaur Found in Carnian/Norian Triassic Portugal

The first phytosaur (Diapsida, Archosauriformes) from the Late Triassic of the Iberian Peninsula

Authors:

Mateus et al

Abstract:

The Triassic was first defined based on the characteristic threefold sequence of rocks that crops out across much of Europe, and many of the first records of Triassic dinosaurs, crocodile-line archosaurs, and other vertebrates were discovered in Great Britain, France, Switzerland, and Germany. These discoveries helped paint a general picture of the Triassic as a critical transitional interval in Earth’s history, during which Earth recovered from a devastating extinction and more modern terrestrial ecosystems composed of dinosaurs, crocodylomorphs, squamates, and mammals were first established (e.g., Sues and Fraser, 2010). Over the past 50 years, however, the focus of Triassic vertebrate research has shifted to the fossil-rich deposits of South America and western and northeastern North America. The European record has been overshadowed, but new discoveries are stimulating a major expansion of Triassic vertebrate work across Europe, especially in Germany and Poland (e.g., Gower, 1999; Dzik, 2001; Schoch, 2006; Dzik and Sulej, 2007).

Despite considerable exposures of Triassic terrestrial sedimentary rock, the Iberian Peninsula of southwestern Europe has to date contributed little to this renewed focus on the European Triassic vertebrate record. This situation is changing with recent descriptions of Triassic terrestrial vertebrates from Spain (e.g., Fortuny et al., 2011) and Portugal (Witzmann and Gassner, 2008; Steyer et al., 2011). Here, we describe the first Iberian record of a major clade of Triassic vertebrates, the long-snouted, semiaquatic phytosaurs that are part of the great post-Permian archosauromorph radiation (e.g., Stocker and Butler, 2013). This specimen, the posterior end of a mandible and associated teeth, was discovered in southern Portugal, 2.7 m above and about 5 m lateral to a bonebed of the temnospondyl Metoposaurus in a mudstone unit within the same stratigraphic section as Central Atlantic Magmatic Province (CAMP) basalts, in a classic northern Pangean rift sequence (Fig. 1). The discovery of this specimen helps to better constrain the age of the Portuguese site and provides further evidence that basal phytosaurs were widely distributed in areas with a monsoonal-type climate during the Triassic (e.g., Buffetaut, 1993; Brusatte et al., 2013).