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Placodus gigas is an unarmored placodont marine reptile (Diapsida, Sauropterygia) known from the Middle Triassic of Europe, most commonly found in the shallow marine carbonate facies of the German Muschelkalk (lower Anisian to middle Ladinian, approximately 243–235 Ma). Generally, the morphology of the skull is well understood, with the exception of the braincase, which is partially obscured by dermatocranial bone. Two skulls that display well-preserved and intact chondrocranial elements were scanned using industrial micro-computed tomography (μCT), thus revealing parts of the braincase that were previously obscured and allowing a new three-dimensional reconstruction of the region to be constructed. This includes a complete osteological description, the first reconstruction of a sauropterygian vestibular apparatus, and a new virtual cranial endocast. The morphology of the braincase and sphenoid region has been revised, revealing the position of the hypophyseal pit. The enigmatic ‘alisphenoid bridge’ has been reinterpreted as being a dorsally extended dorsum sellae. The vestibular apparatus is shown to have strongly dorsoventrally compressed vertical semicircular canals, a commonly observed morphology of other marine reptiles, and an ‘alert’ head position of about 20°, indicating a highly aquatic lifestyle. Because placodonts are the sister group to all other sauropterygians, these new data are of great comparative and phylogenetic significance, providing insight into some of the morphological and functional changes that occurred on the stem leading to the more derived sauropterygians. [ABSTRACT FROM AUTHOR]

A recent article published by Diedrich (2011a, Hist Biol. iFirst online, 1–19, doi: 10.1080/08912963.2011.575938) aspired to provide a complete revision of the known material of the placodont genus Cyamodus Meyer, 1863 from the Germanic Basin of central Europe. It is the latest in a series of similar articles by the same author (see Diedrich 2010, Palaeogeogr Palaeoclimatol Palaeoecol. 285(3–4):287–306; 2011b, Nat Sci. 3(1):9–27 for overview) focussing on the European members of the Placodontia (Reptilia: Sauropterygia), a diverse group of enigmatic marine reptiles known from Triassic shallow marine deposits. In a similar fashion to some previous works by Diedrich (see Tintori 2011, Palaeogeogr Palaeoclimatol Palaeoecol. 300(1–4):205–207 for similar points of criticism), this newest article demonstrates a narrow scope of presenting and discussing data, including omitted articles relevant to the topic, and over-interpretation of results, all with the aim of embedding the idea of placodonts being herbivorous Triassic ‘sea cows’ feeding on macroalgae (Diedrich 2010, 2011b). The present contribution is intended to clarify mistakes and misinterpretations made by Diedrich (2011a), to incorporate vital citations previously omitted which allow alternative interpretations, and to put the paper into perspective by including a more general evolutionary and paleoecological overview of the remaining placodonts. [ABSTRACT FROM AUTHOR]