Vertebrates

The Origin of Tetrapods  The first vertebrates on land were amphibians in the Devonian  May have arose from the rhipidistian (features) or a lungfish (DNA)

Origin of Tetrapods

Classification  Phylum: Chordata  Subphylum: Vertebrata  Superclass: Gnathostomata  Class: Amphibia –Order: Urodela (Salamanders) –Order: Anurans (Frogs and Toads) –Order: Apodans (Caecilians)

Class: Amphibia  Two lives –refers to metamorphosis of many frogs  Skin smooth and moist (cutaneous respiration)  Three chambered heart with a double circulation system  Mesolecithal eggs with jelly-like membrane

Order: Urodela  400 species  Salamanders  Retain their tail as adults  Limbs are at right angles to the body  Carnivorous

Order: Anurans  3500 species  Frogs and Toads  Lose their tail as adults  Hind limbs are adapted for jumping  Tongue connected to front of mouth  Secrete mucus

Order: Apodans  150 species  Caecilians  Legless and blind

Evolution of the Amniotic Egg  Allows animals to complete their entire life cycle on land  Has shell that retains water (or is lost when kept inside mammals)  Specialized extraembryonic membranes (not part of the animal)

Evolution of the Amniotic Egg  Amnion - Protects from dehydration and mechanical shock  Yolk Sac - Nutrient storage  Albumin - Nutrient storage  Allantois - stores waste, gas exchange  Chorion - gas exchange

Amniotes

Amniotes

How Reptiles differ from Amphibians  Tough, dry skin  Amniotic egg  Crushing or gripping jaws  Copulatory organs  More efficient circulatory system with a higher blood pressure  More developed lungs (thoracic breathing)  Better water conservation  Better body support and limbs  Better nervous system

Classification  Phylum: Chordata  Subphylum: Vertebrata  Superclass: Gnathostomata  Class: Reptilia (not real) –Class: Testudines (Turtles and Tortoises) –Class: Spenodontia (Tuataras) –Class: Squamata (Lizards and Snakes) –Class: Crocodilia (Crocodiles and Alligators)

Reptile Radiation  Synapsids (therapsids) - led to mammals  Sauropsids –Anapsids (turtles) –Diapsids (all others)

Class: Testudines (Chelonia)  Evolved on land and returned to water (lay eggs on land)  Protective Shell –Carapace –Plastron

Class: Sphenodontia  Tuataras –Two living species (New Zealand) –Not a True Lizard (no external ears) –Very Primitive (similar to mesozoic reptiles –Well developed eye below skin?

Class: Squamata  Lizards –geckos, iguanas, skinks, chameleons  terrestrial, burrowing, aquatic, arboreal  moveable eyelids  Paired copulatory organs  Lower jaw not attached to skull

Class: Squamata

 Snakes  Lack limbs  Lack moveable eyelids  Jacobson’s organ  Pit Vipers (heat)  Venom –neurotoxins –hemolytic enzymes

Class: Squamata

Feeding Adaptations  Teeth curved and pointed inward  Hinged Quadrate bone  Bones of jaw are attached by muscles and ligaments  Moveable palate  Elastic skin  No sternum

Class: Crocodilia  Largest living reptiles  Most closely related to dinosaurs  Complete secondary palate  Four chambered heart  Nest temperature

Dinosaurs and Pterosaurs  Dinosaurs –Ornithischian –Saurischian (closely related to birds)  Pterosaurs –flying reptiles

Class: Aves

 Feathers  Hollow Bones  Wings  Endotherm  Organs reduced  Beak without teeth  No bladder

Class: Aves  Wishbone – Called a Furcula made up of the fused clavicles.

Class: Aves  Muscles – –Pectoralis muscle pulls wing down –Supracoracoideus raises wing

The Origin of Birds  Feathers  Beak with teeth  Long Tail  Wing with claw

The Origin of Birds  Sinoauropteryx - protofeathers?  Caudipteryx - true feathers

Bird Classification  8600 species of bird (28 orders) –60% are passeriformes (perching birds)  Two major Types –Ratites  Ostriches, Emus –Carinates  Song birds

Class: Mammalia  Hair  Endothermic  Mammary glands  Live birth (2 exceptions)  Teeth differentiation  Jaw modified to incorporate bones into inner ear

The Evolution of the Mammal  Reptile’s lower jaw made up of several bones  Reptile’s middle ear made up of one bone  Mammal’s lower jaw made up of one bone  Mammal’s jaw joint has shifted  Mammal’s middle ear made up of three bones

Mammal Classification  Monotremes –lay eggs –no nipples

Monotreme

Mammal Classification  Marsupials –born early –develops in pouch

Marsupials

Marsupials

Mammal Classification  Placentals –Eutherian mammals –development in uterus joined by placenta

Proboscidea

Sirenia

Edentata

Rodentia

Lagomorpha

Carnivora

Artiodactyla

Cetacea

Perissodactyla

Chiroptera

Insectivora

Primate Evolution  Ancestral primate (arboreal) (65 mya) –binocular vision –opposable thumb  Prosimians –lemurs, tarsiers pottos

Primate Evolution  Ancestral primate (arboreal) (47 mya) –binocular vision –opposable thumb  “Ida” – Missing Link –No claws –Lack a tooth comb –Short limbs –Short face –Talus – corner of leg/foot

Primate Evolution  Anthropoids (50 mya) –Monkeys  Old World –External nares close together –Opposable thumbs –Calloused ischial tuberosities

Primate Evolution  Anthropoids (50 mya) –Monkeys  New World –Broad flat nasal septum –Nonopposable thumb –Prehensile tail

Primate Evolution  Hominoids (30 mya) –apes

Human Evolution  Brain Size  Jaw Size  Bipedalism  Reduced Size difference in sexes  Family Structure

Human Evolution  Sahelanthropus  (6.5 million years ago)

Human Evolution  Laetoli Footprints  (3.5 million years ago)

Human Evolution  Australopithecus  (3.24 million years ago)

Primate Evolution  Homo genus ( mya) –Homo sapiens (200,000 years ago)

Primate Evolution  Neanderthals (40,000 years old)

Human Evolution  Turkana Boy (Homo ergaster)  (1.7 million years ago)  Between H. habilis and H. erectus

Origin of Modern Humans  Out of Africa (monogeneus) –all races of humans evolved from an ancestor in Africa  Multiregional –Each race evolved from regional populations of Homo erectus