Vertebrate Zoology - V. M. Konstantinov 2011

Chordates
Terrestrial, or Tetrapod, Vertebrates — Vertebrates with Embryonic Membranes
Class Reptilia, or Reptiles — Subclass Anapsida — Order Testudines (Turtles) — Suborder Pleurodira

Representatives of the suborder Pleurodira (Side-necked turtles, about 50 species), when retracting their HEAD into the shell, bend the neck to the side so that the head rests in either the right or the left armpit. Consequently, the transverse processes of the cervical vertebrae and their associated musculature are strongly developed. A characteristic feature is the rigid fusion of the pelvis with the ventral and dorsal shields of the shell. All species in this group are aquatic and distributed across the Southern Hemisphere: in Africa, Australia, and South America.

In the rivers of the Orinoco and Amazon basins lives a distinctive species locally known as the arrau or tartaruga (Podocnemis expansa). This is a large turtle whose shell reaches up to 80 cm in length. It inhabits forest rivers and swamps, occasionally forming large aggregations, and lays its eggs in the sand on shallow riverbanks.



Last update: 13/08/2026

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