Reptiles, Birds And MammalsPresentation Transcript
Reptiles, Birds and Mammals Our scaly, feathered and hairy friends!
3 Key Adaptations for Life on Land
1. Amniotic Egg
2. Internal Fertilization
3. Water-tight skin
An amniotic egg is a waterproof egg with a shell.
It is named for a particular membrane called the amnion.
The amnion protects the embryo from drying out and surround a fluid filled cavity that cushions it.
The other membranes formed during development of the embryo function in gas exchange, waste removal and supplying nutrients.
The amniotic egg makes it possible to lay an egg on land without needing to return to the water like an amphibian.
In internal fertilization, the male deposits sperm within the female’s body.
The sperm then swims inside the reproductive tube towards the egg.
This allows for reproduction to take place outside of water.
Amniotes have a water-tight skin enriched with a waterproofing protein called keratin.
The keratinized skin prevents dehydration.
Reptile skin has scales which are hard, overlapping structures made of keratin.
Birds have feathers made of keratin.
Mammals have hair, nails and horns made of keratin.
Ectotherms-main source of body heat is the environment-cold-blooded
Endotherms-body heat generated internally by cell metabolism, warm-blooded
History of Reptiles
The oldest reptile fossils have been found in rocks dating from the Carboniferous period about 300 mya.
Reptiles diversified in the Mesozoic era.
At that time, dinosaurs occupied every habitat and ecological role.
Some were very quick and agile indicating that they might have been endotherms.
Some fossils of dinosaurs have been found with feathers.
Dinosaurs became extinct 65 mya from a massive collision with a comet or asteroid.
Diversity of Living Reptiles
6,500 known species
Turtles and Tortoises
Shell of bony plates called scutes
Some aquatic turtles’ shells are soft and leathery
Jaw with horny ridges
Terrestrial turtles are called tortoises
Turtles and Tortoises
Lizards and Snakes
Lizards usually have 4 limbs with the exception of legless lizards
All snakes are predators
Snakes evolved from lizards and some still have pelvises
25% of snakes are venomous and 2 lizards are.
Largest living reptiles
Closely related to dinosaurs
Highly developed brain
Only reptiles with 4 chambered hearts, the others have 3
Alligators have rounded snouts, crocodiles have pointed snouts
Crocodilians Alligator Crocodile
Crocodilians Gavial Caiman
Rare, old species
Different structures than lizards, vestigial third eye and slowest metabolism in reptile class
Live only on islands near Australia and New Zealand
Molecular and fossil evidence indicated birds and crocodilians are more closely related to dinosaurs than any other reptiles.
Feathers-modified scales made of keratin used for flight and insulation
Birds have a system of branching air sacs that function with their lungs in respiration.
The air sac system helps supply the high levels of oxygen that support a high rate of metabolism.
Air sacs also reduce the overall body weight of the bird.
Bird bones are honeycombed and mostly hollow but are still structurally strong.
Bird’s Adaptations to Decrease Body Weight
1. Air sac system
2. Honeycombed bones
3. Absence of many internal organs
4. Absence of teeth
Gizzard- muscular organ often containing small stones that grind seeds and other food
Crop- sac like organ used for temporarily storing food
4 chambered heart is efficient by keeping oxygen rich blood completely separate from the oxygen poor blood.
Origin of Birds
Many paleontologists agree the ancestor of birds was a small, feathered dinosaur.
A famous bird fossil, Archaeopteryx lived 150 mya.
It had a mixture of bird and reptilian features.
The hoatzin-resembles early birds
Diversity of Birds
Rapid altitude changes-finches, cardinals
Soar and glide on air currents-falcons and albatrosses
Flap or buzz quickly and can hover or go backwards-hummingbirds
Flightless swimming/diving birds-penguins
Flightless running birds-ostriches, emus
Made of keratin
Modified to the food source
Toothless and cannot chew
Awww preeeety birdie
Complex courtship behaviors
Complex song communications
Caring for offspring
Origin of Mammals
The oldest fossils of mammals date back about 200 mya to early Mesozoic era.
Fossil evidence indicates mammals evolved from reptiles called therapsids.
Early mammals coexisted with dinosaurs but were mouse-sized and ate insects.
These early mammals were nocturnal and endothermic.
Mammals took over all habitats and diversified once the dinosaurs went extinct.
Mammal-endothermic vertebrate that possesses mammary glands and hair
Therapsids-ancestors to mammals
All Mammals have:
1. Mammary glands (got milk?)
4. Muscular diaphragm that separates lungs and heart from the rest of the body
5. 4 chambered heart
6. Reproduce sexually with internal fertilization (a few exceptions)
7. Most give live birth with few exceptions
Diversity of Mammals
4,500 known species
Mammals Placentals Monotremes Marsupials Embryo develops In a uterus Lay eggs Have a pouch Placenta provides Nutrients to embryo Only live in Australia and Neighboring islands Young born before Fully developed Contains amnion like bird and reptile eggs Mixture of reptilian And mammalian characteristics Most live in Australia and Neighboring Islands, except opossum 4,200 species Platypus and echidna Kangaroos Koalas Opossums Etc..
Lemurs, monkeys, apes and humans
Evolved from tree-welling, insect-eating ancestors about 65 mya.
Flexible shoulder joints
2 eyes with binocular vision
Care for young and nurture offspring for extended period of time
2 Groups of Primates
Lorises, Galagos and lemurs
Madagascar and Comoro islands
Lorises in Africa and Southern Asia
Many have claws not nails
2 Groups of Primates
Tarsiers, New World Monkeys, Old World Monkeys, apes and humans
Tarsiers from Southeast Asia
NW monkeys in Americas have prehensile tails that grasp and are tree-dwelling
OW monkeys are usually ground dwelling like baboons, mandrills or macaques, no external tail
Apes are gorillas, siamangs, orangutans, gibbons, chimps, bonobos and humans
Closest relatives to humans
Prosimians or early primates
Tarsiers are cute!!!!
Primates Asian and African Monkeys
Ape Family Gibbons
Bonobos-Our closest relatives
Human or not?
Bonobos are endangered!
Oldest evidence for bipedalism or upright walking was Australopithecus about 4 mya.
Famous fossil called Lucy.
Other Hominid relatives
How did Humans Arise? Why are we the only ones?
Homo sapiens the most intelligent?
1. Modern humans killed neanderthals?
2. Modern human interbred with neanderthals?
Reptiles Turtles and Tortoises Lizards and snakes Crocodilians Tuataras Hard shell Made of scutes Can be legless or Have limbs Alligators Crocs caimans Rare endangered Longest lived reptiles Snakes evolved From lizards Related to dinosaurs Different physical Characteristics Than lizards