name 'turtle' in scientific terms includes all forms of turtles,
tortoises and terrapins. These names have been applied to infer
something about the life habits of the animals concerned: turtles tend
to be marine, tortoises terrestrial and terrapins freshwater.
Turtles are found in the group Testudines (or Chelonia), and a
further divided into Pleurodira ('side necked') and Cryptodira ('hidden
necked'). The Pleurodira make a sideways bend in the neck to retract
the head, and the Cryptodira make a vertical bend.
The earliest modern turtle was Proterochersis,
a pleurodire from the late Triassic of Germany, and fossil forms were
worldwide in a range of habitats. Today, pleurodires are all freshwater
and restricted to the southern hemisphere. The earliest cryptodire was Kayentachelys from
the early Jurassic of Arizona. Most modern turtles are cryptodires, and
are found worldwide.
there are over 290 species of turtle in 99 genera and 14 families,
although many are endangered.
The Hawksbill Seaturtle (Eretmochelys
imbricata), a critically endangered Caribbean turtle, 90cm
long. Halliday & Adler 2004
The Eastern Box pond turtle (Terrapene carolina),
15cm long, North America, freshwater. http://www.turtleatlas.com/IDtool.cfm
The Indian Star Tortoise (Geochelone
elegans), dry forests in southern India, 25cm long. http://www.thebigzoo.com/animals/zoom/Geochelone_elegans_001.asp
The Matamata (Chelus
fimbriatus), a large (45cm long) freshwater turtle from
the Amazon basin. Halliday & Adler 2004