Araripemys barretoi (Price 1973, Meylan 1996; Early Cretaceous, 120 mya) is one of the oldest known pleurodires (side-neck turtles). It had a very long neck and a rather low skull. The palate is solid. A lateral temporal fenestra appears. The rostrrum was very short. The posttemporal fenestra extend anterior to the jugal. The cervicals and unguals were both arrow-shaped. Metatarsal 5 is a deep crescent. Three fenestrae pierced the plastron. No interclavicle appears to be present.

Distinct from Meylan, the squamosal is actually fused with the quadratojugal and the supratemporla was earlier misidentified as the squamosal.

Chelus frimbriata (Matamata; extant, Schneider 1783; 45 cm carapace length) a side-neck turtle (pleurodire) with huge hyoids that help its neck expand quickly to suck in swimming prey items. This skull also qualifies for a top-ten position among the weirdest of all reptile skulls.

It was first named Testudo fimbriata by Schneider 1783. It was renamed 14 different times over two centuries and renamed Chelus fimbriata in 1992. CT image copyright Digimorph.org and used with permission.

Meylan PA 1996. Skeletal morphology and relationships of the early Cretaceous side-necked turtle, Araripemys barretoi (Testudines: Pelomedusoides: Araripemydidae), from
the Santana Formation of Brazil. Journal of Vertebrate Paleontology 16(1):20-33.

Price L 1973. Quelonio amphichelydia no Cretaceo inferior do nordeste do Brazil. Revista Brasileira de Geociencias 3:84-96.

Schneider JG 1783. Allgemeine Naturgeschichte der Schildkröten, nebst einem Systematischen Verseichnisse der einzelnen Arten. Müller, Leipzig. xlviii + 364 p.

wiki/Chelus
wiki/Araripemys