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Palatodonta is an extinct genus of Neodiapsida reptile known from the early Middle Triassic (early Anisian stage) of the Netherlands. It was initially described in 2013 as a basal Placodontiformes closely related to a group of marine reptiles called , characterized by their crushing teeth and shell-like osteoderm. Under this interpretation , Palatodonta is transitional between placodonts and less specialized reptiles. Like placodonts, it has a row of large teeth on its palate, but while these teeth are thick and blunt in placodonts, Palatodonta has palatal teeth that are thin and pointed (like the teeth that line the jaws of most other reptiles). A 2023 study instead classified it as a sauropterygomorph and the sister taxon to Eusaurosphargis. In other words, it is close to, but not within, Sauropterygia (the group containing placodonts and other marine reptiles such as and ).
The temporal region (behind the orbit) has two large openings: an upper temporal fenestra which is encircled by bone, and a lower temporal excavation which is open from below. This form of modified diapsid skull is common in early sauropterygians (including Paraplacodus) as well as modern . The upper rear part of the skull roof is composed of the Parietal bone, which enclose a large Pineal foramen and each possess a convex bulge in their outer rear portion. Two large curved bones separate the orbit from the upper temporal fenestra: the Postfrontal bone and Postorbital bone. The postorbital sends back a rounded plate; this plate makes up part of the postorbital bridge, a bony bar which separates the two temporal openings. The postorbital bridge is set relatively low on the skull, so that both temporal openings are well-exposed from the side. The jugal also contributes to the postorbital bridge, as well as the front edge of the lower temporal opening. It extends back far enough to contact the large and complex Squamosal bone, thus excluding the postorbital bone from the lower temporal opening. The tendency of the jugal to contact both the prefrontal and squamosal is a trait only shared with Placodus among placodonts. The rear edge of the lower temporal opening is formed by a tall and narrow bone. This bone was originally identified as a Quadrate bone, which would have articulated with the lower jaw. An alternative interpretation considers it to be a reduced quadratojugal, which was previously reported as absent in Palatodonta and basal placodonts.
Micro-CT of the specimen reveals more details of the jaw and internal structures of the skull. The mandible was much more slender than in placodonts, though the rear part is not fully preserved. The dentary has at least 14 pointed teeth which are sharp and narrow, though they become larger and more robust further back in the jaw. The rear of the jaw includes a low Coronoid bones, a thin surangular, and an elongated Angular bone which likely contains the jaw joint. The palatine bone, which lies along the palate (roof of the mouth) parallel to the maxilla, hosted a single row of large teeth similar to those of the maxilla. This is a specialization relative to most other reptiles, which lack palatine teeth or have multiple rows of tiny denticles. Placodonts are another exception with a single row of large teeth on their palatine, though their teeth are broad and plate-like. Other fragments of palate bones, such as the vomer and Pterygoid bone, lack teeth or denticles. The only preserved portion of the braincase is a basisphenoid, the bone which connects the base of the braincase to the palate. The basisphenoid has two holes for each internal carotid artery as well as stout vertical prongs. Various disarticulated phalanges (finger bones) are mixed up with the skull.
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