Reptiles and Birds

Adaptations for Living on Dry Land Amniotic egg –Leathery shell –Amniotic membrane –Retains fluid in egg Lung breathing young Internal fertilization Water proof skin Kidneys can reabsorb water

Amniotic Egg

Amniotes

Lung Breathing Young

Reptile Skin

Kidney Structure

Scales Fish – dentin (bone-like) Reptile – keratin –Evolved Feathers - birds Hair - mammals

Feather Structure Made of keratin –Same protein found in nails, hair and skin Modified scales

Bone Structure Reduce weight Pneumatized – filled with air Marrow some marrow still present –Blood cell production

Forelimb Structure

Pectoral Muscles

Wing Aerodynamics

Flight Feathers Reduction in weight –Pneumatized bones – air filled bones –One functional oviduct and ovary Large breast muscles Enlarged sternum with keel

Bird Breathing One way system No diaphragm – air sacs act like bellows to pump air into lungs No alveoli – exchange occurs in thin tubes More efficient than mammalian breathing –Allows birds to breath in low oxygen conditions

Bird Breathing

Dodo Bird – Flightless Bird

Ovary One functional ovary and oviduct (left) Fertilization occurs in upper oviduct Albumin added Shell gland produces hard shell Complete fertilized egg exits through cloaca

Parental Care of Young Nest preparation Egg incubation Feeding Protection

Mating Systems Monogamy –Mate for life Swans, pigeons, geese –Seasonal monogamy Most songbirds Polygamy –Male with many females Turkey, grouse

Newly Hatched Young Precocial –Covered with down –Can see –Mobile (walk, run, swim) –Forage for food Altricial –Naked –Blind –Remain in nest –Fed by parent or parents

Altricial Both parents often needed for feeding –Insects, fruit, rodents, birds Pigeons –Pigeon “milk” –Produced in crop

Nest Parasites Lay eggs in smaller birds nest –Parasitic bird usually hatches first –Parasitic bird is larger and pushes out other young and eggs Cowbird, cuckoo –Host birds are often smaller songbirds Wrens, blackbirds, sparrows

Cowbird