Flashcards in Chordates III (Amphibians, Non-Avian Reptiles) Deck (37)
How did the pharynx evolve to support terrestrial vertebrates?
The increased respiratory function supported high metabolic rates
How did the Nervous system evolve to support terrestrial vertebrates?
Evolution of new cell types
-Neural Crest cells (neurons) promoted development of brain, skull and sensory organs
What synapomorphic trait do tetrapods share?
Paired limbs used for terrestrial locomotion
What synapomorphic trait do amniota (mammalia, reptilia (including aves)) share?
Egg with amnion
What is the clade Gnathostomata? Which Classes does it include?
Craniata with jaws
-Chondrichthyes, Actinopterygii, Sarcopterygii, Amphibia, Mammalia, Reptilia (including aves)
What is the Clade Craniata and which classes does it include?
Craniata = Vertebrata
-Euchordates with a cranium
Mychi, Petromyzontida, Chondrichthyes, Bony Fishes, Tetrapods
When did Vertebrates invade land? Who preceded them?
During the Devonian period (~400 mya)
-Beat by vascular plants, molluscs, arthropods
-Means there was plenty of food available for them
How did Vertebrates adapt to life on land?
LIMBS from lobe-fins for support air has less buoyant density than water
LUNGS and cutaneous respiration oxygen content higher in air than water
Prevent DESICCATION through behavioral, physiological, and morphological adaptations
TEMPERATURE Regulation through behavioral, physiological, and morphological adaptations (ectothermic to endothermic)
What are the characteristics of Class Amphibia?
4 limbs with bony skeletal frame
-Lungs with internal nostrils
-Ears & Eyes adapted for air
-Larvae and some adults have lateral line systems
-Thin, moist skin desiccates easily
How does the brain in Amphibia develop?
All carnivorous so need to be clever
-Forebrain - olfaction
-Midbrain - vision
-Hindbrain - hearing, balance
How did Amphibia heart develop?
3-Chambered Heart (2 atria and 1 ventricle)
-Double circulation: oxygenated blood returns to heart
-Skin has lots of blood vessels (cutaneous respiration)
What are the features of the Class Amphibia, Order Gymnophiona (Caecilians)?
Elongated, limbless amphibian with dermal scales
-Burrowing or aquatic
What are the features of the Class Amphibia, Order Urodela (Salamanders)?
-Mostly in temperate regions
-Most with limbs of similar size and set at right angles
-Larvae and adults carnivorous
What are the features of the Class Amphibia, Order Anura (Frogs/Toads)?
Aquatic and Terrestrial
-Temperate and Tropical regions always close to water
No tail in adults, present in larvae
Hibernation in temperate zones (freeze as larvae)
Herbivores as larvae
What is the life cycle of the Class Amphibia, Order Anura?
External fertilization by amplexus (male holds on to female and releases sperm on to eggs)
-Tail, gills reabsorbed
-legs, lungs develop
What kind of skeletal system do Class Amphibia have?
What mode of feeding do Class Amphibia have?
Carnivores but larval herbivores
What kind of reproduction do Class Amphibia exhibit?
What is significant about the Clade Amniota?
Further adaptations to terrestrial life
-Shelled egg, no gilled larval form
-Presence of Amnion
What is the Amnion?
Protects embryo in the amniotic cavity
What is the Yolk sac?
Encloses a reserve of nutrients. Gets smaller with ages
What is the Allantois?
Contains wastes from embryo. Gets bigger with age.
What is the Chorion?
Together with allantois, allows gas exchange.
From outside to inside, what are the parts of the Amniotic egg?
Shell > Albumin > Chorion > Allantois & Yolk Sac > Amnion > Amniotic Cavity > Embryo
What further adaptations to terrestrial life do Clade Amniota exhibit?
-Thicker, keratinized skin (scales, feathers, hair) not involved in respirations
-Stronger jaws with mobile tongue
Clade Amniota have a more active life-style, what did this result in?
Transition to high-pressure blood vascular system
-Non-avian reptiles: similar to amphibians (3-chamber heart allows lung bypass)
-Crocodilians, birds, mammals: 4-Chamber, no mixing, high pressure
Expanded brain and sensory organs
What is an Anapsid, Synapsid, and Diapsid skull?
Clade Amniota evolved from ancestors with an Anapsid skull (no temporal opening)
Synapsid Skull (1 temporal opening)
Diapsid Skull (2 temporal openings)
-Lizards, Snakes, Turtles, Crocodilians, Birds (Diapsida)
What is animals are part of the Order Sphenodonta?
Tuataras (type of lizard)
What is animals are part of the Order Squamata?
Other lizards, Monitors, Snakes