REPTILES • Scientific Classification of Reptiles • To creep Kingdom: AnimaliaPhylum: ChordataSubphylum: VertebrataClass: Reptilia
REPTILES • REPTILES • tetrapods - 4 legs adapted for land, hip/girdle • Amniotes - animals whose embryos are surrounded by a fluid filled amniotic membrane • Four surviving orders:
Crocodilia (crocodiles, caimans and alligators): 23 species • Sphenodonta(tuataras from New Zealand): 2 species - Wedge Tooth • Squamata (lizards, snakes and Worm lizards) approximately 7,600 species - scaly skin • Testudines (Tortoise) Chelonia (Turtles : approximately 300 species – to seize
Firs known reptile fossil • 350 MYA • Carboniferous period • Drier conditions gave rise to the first adaptive radiation of reptiles • by late Triassic and Jurassic periods • Age of Reptiles – Mesozoic • 245 MYA
REPTILES Reptiles are found on every continent except for Antarctica, main distribution comprises the tropics and subtropics. modern species of reptiles do not generate enough heat to maintain a constant body temperature and are thus referred to as "cold-blooded" (ectothermic).
REPTILES Sea Turtle an exception: a reptile that elevates its body temperature well above that of its surroundings.
REPTILES Reptiles evolved from tailed amphibian ancestors. There are nearly 8000 • A reptile has the following features; ectothermic dry, scaly skin tough shell on eggs eggs are laid on land - “enclosed the pond”
REPTILES • The Rise of Amniotes - Reptiles During the late Carboniferous, amphibians gave rise to the amniotes (birds, reptiles, mammals). A. Four features were critical to amniotes’ escape from water dependency: 1. They produce amniote eggs with internal covering membranes and a shell, which allow the eggs to survive in dry habitats.
REPTILES • Amniote egg contains a membraneous sac that surrounds and protects the embryo.
REPTILES • Allantois Greek word for sausage respiration and excretion webbed with blood vessels. liquid waste from the embryo.
REPTILES The allantois functions similarly in monotremes, which are egg-laying mammals.
REPTILES 3 They have internal fertilization. 4 Their kidneys are good at conserving water. 5 scaly skin water conservation
REPTILES • “Reptiles” demonstrate certain advantageous features compared to amphibians. Modification of limb bones, teeth, and jaw bones allowed greater exploitation of the insect life Development of the cerebral cortex permitted greater integration of sensory input and motor response. Well developed lungs
REPTILES Descendants of the surviving dinosaurs became the lineage of reptiles. 4 living orders
REPTILES • Circulatory systems Fish Bird, Mammal Reptile Amphibian
REPTILES Humans, birds, and mammals have a 4-chambered heart that completely separates oxygen-rich and oxygen-depleted blood. Fish have a 2-chambered heart in which a single-loop circulatory pattern takes blood from the heart to the gills and then to the body. Amphibians have a 3-chambered heart with two atria and one ventricle.
REPTILES The disadvantage of the three-chambered heart is the mixing of oxygenated and deoxygenated blood. Most reptiles have an incomplete division in the ventricle “ 3 ½ chambers” Crocodiles and alligators have 4 complete chambers
REPTILES • A Sampling of Existing Reptiles – (Latin, to creep) A. Turtles – Testudines 1. The distinctive shell offers protection while conserving water and body heat.
REPTILES 2. The shell is connected to the skeleton. Their teeth are tough, horny plates designed for gripping & chewing food. 3. Turtles lay their eggs on land, where predation is high.
REPTILES • Anatomy of a Box Turtle
REPTILES • Turtle shell structure
REPTILES • Turtle eggs and newborn
REPTILES • Lizards 1. Most lizards are small-bodied insect eaters; their most usual habitats are deserts and tropical forests. 2. Lizards are also prey for many other animals, but are quick in movement and have the unique ability to sever their own tails if it is grabbed by a predator.
REPTILES • Lizards
REPTILES & AMPHIBIANS • Scientific classification Order: Squamata 95% of all living reptiles are in this group
REPTILES & AMPHIBIANS • Snakes 1. Snakes are limbless but retain vestiges of hind limbs; they are excellent predators. 2. Snakes have the ability to swallow prey larger than they are due to flexible skull and jaw bones. 3. All snakes are carnivores. Some suffocate their prey, and some kill their prey with venom.
REPTILES & AMPHIBIANS 95% of all living reptiles are composed of Lizards and Snakes.
REPTILES & AMPHIBIANS • Tuataras 1. Although they resemble lizards, they are evolutionarily more ancient. They resemble amphibians with the brain and the way they walk. 2. They do not engage in sex until they are twenty years old!.
REPTILES & AMPHIBIANS 3. Only two species remain today; they live on islands off the shore of New Zealand. 4. Like lizards, tuatarus have a 3rd eye under the skin with a retina, a lens, and nerves to the brain. They also may live to be 60 years old.
REPTILES & AMPHIBIANS • Scientific Classification of Tuataras Order: Sphenodontia
REPTILES & AMPHIBIANS • Crocodilians 1. Crocodiles and alligators all live in or near water. 2. They are the largest living reptiles. 3. The body plan includes a long snout; body temperature is regulated behavior- ally (ectothermic).
REPTILES & AMPHIBIANS 4. The ventricle of the heart is divided into right and left chambers – more like the heart of birds than that of other reptiles.
REPTILES & AMPHIBIANS 4. Like other reptiles and birds, crocodilians adjust body temperature with behavioral and physiological mechanisms. 5. They are like birds in displaying complex social behaviors, such as parents guarding nests and assisting hatchlings into water. This trait and others suggest that crocodilians and birds share a common ancestor.
REPTILES & AMPHIBIANS • ReptilianOrders • Procolophonida (extinct) • Araeoscelidia (extinct) • Avicephala (extinct) • Younginiformes (extinct) • Ichthyopterygia (extinct) • Placodontia (extinct) • Nothosauria (extinct)
REPTILES & AMPHIBIANS • Orders (cont.) • Plesiosauria (extinct) • Prolacertiformes (extinct) • Pterosauria (extinct) • Saurischia (extinct) • Ornithischia (extinct)
REPTILES & AMPHIBIANS • Reptilian Orders (cont.) • Testudines • Squamata • Sphenodontia • Crocodilia