Chapter 31 Reptiles & Birds

Evolution

Hylonomus (hylo- "forest" + nomos "wanderer") earliest known reptile lived 315 MYA - about 12 inches long -

Dinosaurs are reptiles that walked leg below hip and either had: 1.Bird hips (Ornithischia)2.Lizard hips (Saurischia).

Evolution - Mesozoic Era

Earliest known reptile lived 315 MYA / earliest dinosaur 245 MYA

Mesozoic Era

2-7 centimeters a year = 730-2,555cm = 7.3-25.55m

Dinosaur Evolution

Extinction - 65MYA

Adaptive Radiation

Groups of Reptiles & BirdsReptiles1. Lizards2. Snakes3. Crocodilians4. Turtles & Tortoises5. Tuataras - primitive

scales, no external ears, third eye

Birds1. Song Birds2. Shore Birds3. Birds of Prey4. Wading Birds5. Sea Birds6. Game Birds

Amphibians1.Toads2.Frogs3.Salamanders

Mammals1.Placental Animals2.Marsupials3.Monotremes

Monotremes &

Kangaroo

Evolution

Reptile: 1. Dry scaly skin2. Ectothermic3. Tetrapods4. Amniotes – terrestrial eggs

Birds:1. Feathers2. Endothermic3. Amniotes

Amphibians1.Permeable Moist Skin2.Tetrapod3.Four Digits Front & Five on Back Limbs4.Ectothermic

Mammals1.Produce Milk2.Have Hair3.Lower Jaw Single Bone4.Middle Ear 3 Bones5.Have a diaphragm6.Live birth all but..7.Endothermic

Avian Skeletal StructureBones1.Hollow reinforced with struts2. Fused collar bone3. Large keeled sternum

Amphibians1. Reduced or No ribs that do not meet the sternum

Snake Skeleton

Snake Jaws

Scales

Evolution of Feathers

Feathers

Contour FeathersDown

-Preening-Molting

Movement

Types of Flight1.Straight2.Hovering3.Soaring4.Dive5.Swimming6.Landing7.Take Off

Avian - Respiratory SystemAir Sacs expand rather than lungs

1. Inhalation - air flows into abdominal and posterior sacs – through lungs2. Exhalation – air in sacs moves to lungs3. Inhalation – air in lungs moves to

interclavicular, thorasic, & anterior sacs

4. Second Exhalation – air moves out

Reptilian Respiratory System

Limited cloacal breathing

Lungs are necessary in all reptiles, but filling them is achieved differently. Many reptiles must hold their breath to run as they use the same muscles for breathing and physical effort.

Snake Respiration

Snakes breathe by contracting muscles between their ribs. Unlike mammals, they lack a diaphragm.. Inspiration is an active process (muscles contract), whereas expiration is passive (muscles relax).

In most snakes the right lung is usually the largest and extends for over a 1/3 of the body. The left lung is then VERY small or absent.

Bull SnakeTrachea

Snake Digestion

During periods of fasting the lining, or mucosa, of the small intestine becomes atrophied, conserving the snake’s energy and resources.

Snakes become dormant after large meals and if threatened right after a meal they may regurgitate to escape.

Feeding stimulates rapid growth of the intestinal lining and the liver and enters into a period of rapid growth and increased activity.

Digestion

Crop - stores & moistens food (crop milk)

Gizzard - part of stomach used for grinding hard materials - rocks are often used

Stomach

Small Intestine

Large Intestine

Nictitating Membrane

Nictitating Membrane

Put in with eye sight