Dinosaur and Reptile Classification traditional classification scheme



Yüklə 473 b.
tarix10.07.2017
ölçüsü473 b.


Dinosaur and Reptile Classification

  • traditional classification scheme

  • Subclass Anapsida (cotylosaurs, turtles)

  • Subclass Synapsida (pelycosaurs, mammal- like reptiles; Dimetrodon)

  • Subclass Euryapsida (marine reptiles; ichthyosaurus & Plesiosaurs)

  • Subclass Archosauria (ruling reptiles)

  • Subclass Lepidosauria (scaly reptiles- mosasaurs)


Temporal Fenestre



Cladistic Scheme



Dinosaurs: A General Overview

  • "age of reptiles" mid-late Triassic (250 mya)- Cretaceous (180 mya)

  • Thecodont ancestry

  • size: initially small--->huge



skeleton

  • hollow bones

  • bipedalism

  • unique pelvic structure (triradiate & quadraradiate pelvic structures)

  • tail large; carried off the ground as a counterweight



"The Great Extinction"

  • occurred at the end of the Mesozoic (65 mya)

  •  

  • > 50% of all species became extinct

  • all tetrapods > 10kg & all marine reptiles went extinct

  • ~ 90% of all protists went extinct

  • extinctions occurred over a period of 10,000-100,000 years or immediately



extinction hypotheses

  • climatic change- equitability and seasonality changed

  • impact with extra terrestrial body

  • exotic species exchange via land bridges



Modern Reptiles

  • diversity: 6000 species

      • turtles (anapsid reptiles)
      • snakes & lizards/squamates (lepidosaurs)
      • crocodilians
      • tuatara (Spenodon)
  • amniotes

  • ectotherms (Their blood is NOT cold!)



Integument

  • epidermal scales

      • dry; water proof & mechanical barrier
  • chromatophores

  • ecdysis = molting/shedding

  • claws

  • few skin glands



Skeleton

  • one occipital condyle

  • ossified skull

      • temporal openings- anapsid, diapsid, synapsid
  • secondary palate in some



Circulation/Respiration

  • three or four chambered heart

  • no diaphragm

  • lungs



Excretory System

  • metanephric kidneys

  • uric acid & urea



Feeding

  • herbivores & carnivores

  • venom glands

  • Jacobson's organ



Reproduction

  • internal fertilization

  • oviparous, ovo-viviparous, & viviparous

  • hemipenis

  • parthenogenesis



Chelonia (Turtles)

  • bizarre skeleton

      • ribs fused & outside limb girdles
  • carapace

  • plastron

  • dermal scales

  • ridged beak- no teeth

  • true penis

  • long lived & long generation times

  • oviparity



Squamata (snakes & lizards)

  • diapsid lineage

  • second largest tetrapod group

  • paired copulatory organ

  • protrusible tongue

  • Jacobson's organ





Lizards (Suborder Lacertia)

  • 3300 species; (3 cm- 3 m); 75 Kg

  • most are small (80% < 20 grams)

  • differences from snakes:

  • zygodactylous feet

  • prehensile tails

  • protrusible tongue



Lizard Families

  • Iguanidae- North & South America

  • Scincidae- cosmopolitan

  • Teiidae- North & South America





Snakes (suborder Serpentes)



Snake Venom

  • Hemotoxic- Crotalus, Agkistrodon

  • Neurotoxic- Elapidae

  • Symptoms & Treatment



Crocodylia




Verilənlər bazası müəlliflik hüququ ilə müdafiə olunur ©azkurs.org 2016
rəhbərliyinə müraciət

    Ana səhifə