Reptiles

• Reptiles


  From the Latin word "repere" or "reptum", to creep or crawl
• Reptile mouth


  • Terminal; jaws bear simple conical teeth; in turtles teeth replaced by horny beaks
• Reptile circulatory system


  • Heart usually 3-chambered, 4-chambered in crocodiles; sinus venosus reduced; two systemic arches present; red blood corpuscles oval and nucleated; cold-blooded
• Reptile reproduction

  • Sexes separate; male usually with muscular copulatory organ
  • Fertilization internal; mostly oviparous; large yolky meroblastic eggs, covered with leathery shells, always laid on land; embryonic membranes (amnion, chorion, yolk sac and allantois) appear during development; no metamorphosis
  • Parental care usually absent
• Reptile skeletal and nervous system

  • Brain with better development of cerebrum than in Amphibia; cranial nerves 12 pairs
  • Endoskeleton bony; skull with one occipital condyle (monocondylar); characteristic T-shaped interclavicle present
  • Lateral line system absent; Jacobson's organs present in the roof of mouth
• Cotylosauria


  • Extinct primitive reptiles of the Carboniferous to Triassic period
  • Labyrinthodont amphibians that gradually took on reptilian characters
  • Massive heavy-bodied, four-legged splay-limbed, long-tailed, plant-eating reptiles
• Carnivorous turtle examples

  • Chelhydra serpentina (Snapping Turtles)
  • Macrolemys (Alligator Turtles)
• Tortol

  • Trionyx, Amyda (Aquatic Soft-shelled Turtles)
  • T. gangeticus (Indian Soft-shelled Turtles)
  • T. leithi (Indian Soft-shelled Turtles)
• Tortol

  • Chelhydra serpentina (Snapping Turtles)
  • Macrolemys (Alligator Turtles)