Chapter 18: Amniote Origins and Nonavian Reptiles Flashcards
What are the extant members of Reptilia (Clade Amniota)?
Birds, Turtles, Lizards, Snakes, Tuataras, Crocodilians and Nonavians
About how many species of Nonavian reptiles are there?
9500 species
What are the special derived characters of Amniotes? (4)
-Amniotic egg
- Rib ventilation
- Desiccation resistant skin
- Head, shoulder, and ankle skeletal characteristics
What did the Amniotes Adaptions promote?
Allowed them to be more energetic and exploit dry, terrestrial habitats
What are the 4 extraembryonic membranes associated with Amniote eggs?
Amnion, Allantois, Chorion, & Yolk Sac
Describe the Amnion (Function, Location)
Encloses embryo in fluid (inside); cushions and provides aqueous medium for growth
Describe the Allantois (Function, Location)
Respiration & Excretion; important role in placental development in mammals
Describe the Chorion (Function, Location)
Outer layer of double membrane; contributes to placenta; forms efficient respiratory organ
Describe the Yolk Sac (Function, Location)
Membraneous Sac filled with nutrients that support growth
Describe the Shell of an amniotic egg
May be mineralized (tough), flexible and leathery,
Do all mammal species have a shell?
No, it is absent in most species
What is the function of a shell?
Mechanical support; acts as semipermeable barrier that allows gas exchange and limits water loss
How did amniote skin adapt and change from that of reptiles?
Much thicker, more keratinized, and less permeable to water
How did amniote lungs change/adapt?
Large with larger surface area and ventilated which reflects in the increased metabolic demands
How do aquatic turtles breathe?
Pharyngeal of cloacal respiration
How do sea snakes breathe?
Cutaneous respiration
How did the mouth of amniotes adapt/change?
Stronger jaws for seizing prey, tongue is more muscular and mobile for moving food in mouth
Most amphibians excreate metabolic waste as ____ or ____
ammonia or urea
Describe ammonia
Toxic, even at low concentrations, not adaptive for vertebrates
What do mammals excrete waste as? Describe the sustance
Urea, less toxic and concentrated in kidneys
What do bird/nonavian reptiles excrete
concentrated acid
How did the brain of amniotes change?
Larger brain for more complex behaviors and senses
What are the most distinctive features of a turtle shell?
Dorsal carapace and ventral plastron
What type of reproduction do turtles demonstrate?
Oviparity, eggs are buried in nests in the ground
Describe environmental sex determination
The temperature of the incubation can influence the sex of turtles
What species of turtles is the exception to showing no parental care? What do they do differently?
South American River Turtle; females stay near the nests and when the hatchlings hatch she will call to them and they will migrate together to the flooded forests
What is a major danger to turtles that humans introduced?
Automobile mortality, especially in the Great Lakes region up to 25% of populations are being hit by cars
What are Lizards & Snakes scientifically called?
Squamata
What shared characteristics between lizards and snakes?
Skin with overlapping, keratinous scales
Leglessness- reduction or complete loss of limbs
Are all snakes limbless?
Yes
What is unique about male squamata?
The presence of hemipenes
True/False: Male Squamata use both forks of hemipenes for copulation
False; they are either right or left penised
What have lizards adapted to have in order to survive and maintain prey population?
Determinate growth; 80% of extant species weigh less than a mouse, making them able to eat small insects and become fulfilled with the food
Describe the variety in body forms of Lizards
Smallest: 3cm long (geckos and chameleons) to Largest 3m long (Komodo dragon)
What is another name for snakes?
Serpentes
Snakes usually lack ____ and ____ girdles
pectoral and pelvic
Snakes limbs are said to be _____, meaning _____
Vestigial; reduced in size and no longer functioning
True/False: Snakes unhinge their jaws to eat prey
False, they have extremely kinetic skulls, which allows extensive movement
What is the function of Jacobson’s Organ in snakes?
Receives sensory inputs from tongue and passes them to the brain for interpretation
What is the function of a forked tongue in snakes?
Collects scent molecules and draws them past Jacobson’s organ to transmit the info to the brain
Pythons, boas, and pit vipers have what unique structure?
Pit organs
What is the function of pit organs
Heat senesitive, can distinguish the difference between heat, used to track warm prey and aim strikes
Describe the anatomy of Vipers
large moveable tubular fangs at the front of mouth (venomous)
venom is injected through canals in fangs, after prey is injected viper releases it and follows until it dies
What are the most common species of Vipers in North America?
Rattlesnakes, Cottonmouths, and Copperheads
What species of snakes comprise Family Elapidae?
Cobras, Mambas, Coral Snakes, and Kraits
What is different about Family Elapidae’s fangs?
short, permanent erect fangs in the front of the mouth
How many natural populations of Tuatara are there? What country are they found in?
32 natural populations; Small islands off of New Zealand
Crocodilians are considered _____ because ____.
Living fossils, they have remained relatively unchanged for more than 300 million years
Describe the adaptations that Crodilians have
Well-reinforced skull
Massive jaw musculature
Teeth set in sockets
Complete secondary palate
Describe the birth/reproduction in Crocodilians
Oviparity, 20-90 eggs in clutch, buried in dead vegetation the eggs are laid
Crocodilian eggs sex are determined by temperature. High temp yields ____. Low temp yields _____.
female; male
