HISTORY

Class Reptilia includes the turtles and tortoises (order Chelonia), lizards and snakes (order Squamata), crocodiles and alligators (order Crocodilia) and tuatara (order Rhynchocephalia). These represent only 4 of the 16 orders that lived and flourished in Mesozoic era. Class Reptiles are first vertebrates adapted for life on dry land. The class name refers to the mode of travel (Latin reptum=to creep). Class Reptiles animals show advance over the amphibians in having (i) dry scaly body covenng, adapted to life away from water, (ii) limbs suited for rapid locomotion, (iii) further separation of oxygenated and non-oxygenated blood in the heart, (iv) complete ossification of skeleton, and (v) eggs sutted for development on land with membranes.

Most reptiles live in tropical and subtropical regions, their number declining towards poles. Turtles and snakes are abundant in humid regions. Class Reptiles have radiated towards all kinds of habitat, i.e., land, water and air. In winter they lead dormant life, hibernate in crevices. Snakes are injurious to mankind and still man fears them very much. Many kinds of snakes and lizards benefit man by providing food, by destroying harmful rodents and insects. Skin of snakes and crocodiles is of great economic importance.

DIAGNOSTIC CHARACTERS OF CLASS REPTILIA

  • Body covered with dry skin.
  • Horny epidennal scales, shields, plates and scutes fonn exoskeleton.
  • Hind and forelimbs present. Digits with horny claws.
  • Single occipital condyle.
  • Bony endoskeleton.
  • Fertilization internal.

CLASSIFICATION OF CLASS REPTILIA

CLASS REPTILIA

SUB-CLASS A :- ANAPSIDA​​

  • Skull roof solid.
  • No temporal opening behind eye.

Order 1. Cotylosauria

  1. Primitive reptiles.
  2. Resemble Labyrinthodont amphibians.
    Example :- Seymouria

Order 2. Chelonia

  1. Body broad, covered with a finn shell of rounded dorsal carapace and flat-ventral plastren.
  2. No teeth. Jaws with horny sheath.

Sub-order 1. Atheca – Extinct

Sub-order 2. Thecaphora

    • Neck bends in vertical scurve if retractile.
    • Pelvis not fused with plastron.

Family 1. Testudinidae

  • Shell usually complete with scutes.
  • Limbs with claws, not paddle-like.
    Example :- Chrysemys, Terrapene, Testudo, Kachuga

Family 2.  Chelonidae

  • Limbs flipper-like, shell shield smooth.
  • Horny scutes large.
    Example :- Chelonia, Coretta, Chelone

Family 3. Trionychoidae

  • Soft, shelled turtles.
  • Shell reduced covered by skin.
    Example :- Trionyx
CHELONE (GREEN TURTLE)
CHELONE (GREEN TURTLE)

SUB-CLASS B :- EURYPSIDA​​

  • Skull with single dorsolateral temporal opening bounded by post -orbital and squamosal.
  •  Extinct.
    Example :- Plesiosaurus.

SUB-CLASS C :- PARAPSIDA​

  • Dorsolateral temporal opening in skull bounded by supra-temporal and post Frontal.
  • Extinct.
    Example :- Ichthyosaurus.

SUB-CLASS D :- SYNAPSIDA

  • Skull roof with lower opening behind eye bounded above by post-orbital and squamosal.
  • Extinct mammal-like reptiles.
    Example :- Dimetrodon, Varanosaurus.

SUB-CLASS E :- DIAPSIDA​

  • Skull roof with 2 openings behind eye separated by a bar formed by post-orbital and squamosal.
  • No antero-orbital opening or depression.

Order 1. Rhynchocephalia

  • Living reptiles, lizard-like.
  • Scales granular, a mid-dorsal row of long spines.
    Example :- Sphenodon

Order 2. Squamata

  • Lizards and snakes.
  • Skin with horny epidermal scales or shields.

Sub-order 1. Sauria or Lacertilia

    • Lizards. Body slender. Limbs typically 4.
    • Eyelids movable.

Family 1. Geckonidae

    • Toes often with rounded adhesive pads.
    • Tongue protrusible.
      Example :- Gecko, Hemidactylus

Family 2. Iguanidae

    • Limbs normal. Teeth homodont. (alike). New world lizards.
    • Tongue fleshy, non-protrusble
      Example :- Anolis, Phrynosoma, Sauromalus, Iguana, Crotaphytus

Family 3. Agamidae

    • Limbs normal. Teeth differentiated. Old world lizards.
    • Tongue short and thick.
      Example :- Agama, Draco, Moloch, Calotes

Family 4. Scincidae

    • Limbs and toes often reduced sometimes absent.
    • Scales commonly smooth.
    • Skinks.
      Example :- Mabouia

Family 5. Chamaeleonidae

    • Head angular produced into snout.
    • Tail prehensile. Changes colour.
      Example :- Chameleon

Family 6. Varanidae

    • Large trunk. Limbs stout. Neck and tail long. Monitors.
    • Teeth pleurodont. Tongue long bifid and protrusible.
      Example :- Varanus

Family 7. Helodermidae

    • Poisonous lizards. Rounded limbs. Trunk and tail stout
    • Tongue fleshy and protrusible.
    • Venom potent, fatal to small animals, rarely to man.
      Example :- Heloderma

Family 8. Anguidae

    • Alligator lizards. Body slender with deep fold in skin on each side.
    • Limbs small or none. Tail long, fragile and regenerates.
      Example :- Anguis, Ophiosaurus
  •  
HELODERMA (GILA MONSTER​)
HELODERMA (GILA MONSTER​)

Sub-order 2. Ophidia or Serpentes

  •  Snakes, limbs, feet, ear openings, sternum and urinary bladder absent.
  • Mandibles joined anteriorly by ligament.
  • Poisonous and non-poisonous snakes.

Family 1. Typhlopidae

    • Eyes vestigial under opaque scales, teeth on maxillary bones only.
    • Scales thin, overlapping.
      Example :- Blind snakes (Typhlops)

Family 2. Leptotyphlopidae

    • Teeth only on lower jaw.
    • Vestiges of femur and all pelvic bones present.
      Example :- Leptotyphlops

Family 3. Boidae

    • Vestiges of pelvic girdle and hind limbs as  2 spurs on ventral sides.
    • Cosmopoliton.
      Example :- Python, molurus, Eryx

Family 4. Anilidae

    • Head small, cranium firm.
    • Tail short, scales smooth.
      Example :- Anilius, Cylindrophus

Family 5. Uropeltidae

    • Head small and pointed. Tail short, shield tailed snakes.
    • No vestiges of hind limbs and pelvic girdle.
      Example :- Uropeltis

Family 6. Colubridae

Family 7. Dasypeltidae

    • Ventral spine on anterior vertebrae used to crack shells of birds eggs.
    • Teeth long and slender.
      Example :- Elachistodon, Dipsas

Family 8. Hydrophiidae

    • Tail compressed, used for swimming, venomous and dangerous to man.
    • A pair of short, rigid, erect venom-conducting teeth or fangs.
      Example :- Sea snakes (Hydrophis), Pelamis

Family 9. Elapidae

    • 2 or more short, rigid, erect fangs. Venom powerful and dangerous to man.
    • Tail round and tapered, not compressed.
      Example :- Poisonous snakes. Bungarus, Naja-naja, Elaps

Family 10. Viperidae

    • Paired erectile fangs in front of upper jaw, one on each maxillary bone and folded backward when not in use. Venomous.
    • No pit between nostril and eye.
      Example :- Vipera russelii (pitless viper)

Family 11. Crotalidae

    •  A pit like depression on each side of upper jaw between nostril and eye.
    • Some with horny rattle at end of tail.
      Example :- Ancistrodon (Pitviper), Rattlesnake
snake, terrarium, toxic, Ancistrodon : Pit Viper
Ancistrodon (Pit Viper)

Order 3. Crocodilia

  •  
CROCODILE 8 MOST DANGEROUS ANIMALS IN THE OCEANS​
CROCODILE

Order 4. Pseudosauria  :- Extinct. Ex. Saltopseudois.

Order 5. Saurischia

  • Ischium and pubis diverge.
  • Bipedal or huge 4-footed.
    Example :- (Extinct) Dinosaurs, Tyrannosaurus, Brontosaurus, Diplodiscus

Order 6. Ornithischia

  • Pelvis bird-like.
  • Ischium and pubis together.
  • Extinct. Example :- Dinosaurs, Iguanodon, Triceratops, Stegosaurus

Order 7. Pterosauria

  • Flying reptiles.
  • Forelimbs with wing membranes. Tail long.
    Example :- (Extinct) Pteranodon, Rhamphorhynchus
  •  
OUR POSTS

Leave a Comment

Your email address will not be published. Required fields are marked *