Қоңырқайлар тұқымдасы

Family of turtles
Automatic taxobox
| image = Chelus fimbriatus 2005. jpg
| image caption = Chelus fimbriatus
| fossil range =
| taxon = Chelidae
| authority = Gray, 1831 The family is distributed in Australia, New Guinea, parts of Indonesia, and throughout most of South America. It is a large family of turtles with a significant fossil history dating back to the Cretaceous. The family is entirely Gondwanan in origin, with no members found outside Gondwana, either in the present day or as a fossil.

Like all pleurodirous turtles, the chelids withdraw their necks sideways into their shells, differing from cryptodires that fold their necks in the vertical plane. They are all highly aquatic species with webbed feet and the capacity to stay submerged for long periods of time. The snake necked species (genera Chelus, Chelodina, and Hydromedusa) are largely strike and gape hunters or foragers feeding on fish, invertebrates, and gastropods. The short necked forms are largely herbivorous or molluscivorous, but are also opportunistic, with several species having specialized to eating fruits. The highly aquatic nature of the group is typified by the presence of cloacal breathing in some species of the genera Elseya and Rheodytes. However, some species, such as the eastern long neck turtle (Chelodina longicollis) from Australia spend significant periods of time on land and are considered highly terrestrial. The smaller members of the family include the Macleay River turtle (Emydura macquarii) at around 16 cm, twist necked turtle (Platemys platycephala) at 18 cm and the western swamp turtle (Pseudemydura umbrina) at 15 cm, whereas the larger species such as the mata mata (Chelus fimbriata) and the white throated snapping turtle (Elseya albagula) both exceed 45 cm in shell length. Chelids exhibit XX/XY genetic sex determination, in contrast to most other turtles, which have temperature dependent sex determination.

Members of Chelidae have unique shell morphology. The carapace often has reduced surface exposure of neural bones, or even none at all. This is due to less requirement for enlarged longissimus dorsi muscles in side necked turtles. The inside of the carapace is often heavily buttressed. This has sometimes been seen as a defense mechanism, that is it increases the strength of the shell against biting force, however Thomson (2003)

The oldest records of Pan Chelidae (the clade containing Chelidae and all other species more closely related to Chelidae than other pleurodires) first appear in the mid Cretaceous in South America and Australia, represented by Prochelidella cerrobarcinae from the Cerro Barcino Formation of Argentina, which dates from 118 to 110 million years ago, and indeterminate remains from the Griman Creek Formation, of New South Wales, Australia, dating to around 100 million years ago.

Relationships of the living forms based on Georges et al., 2014. The species in the Chelidae family are distributed across Australia, New Guinea, and South America. Over time they were required to disperse out of concerns of food shortage, habitat destruction, and weather disruptions. In all of these warmer climates, they can be found in turbid waters covered by muck and the root mats of underwater vegetation. The waters that they are found in often lack large species of fish that would put them at risk of predation.