reptiles, mammals, and birds
DESCRIPTION
Reptiles, Mammals, and Birds. Reptiles, Birds, & Mammals. Amphibians. ~400 MYA. Early Reptiles: Reptilomorphs. The earliest ancestors of reptiles are reptile-like amphibians. Remember: what is THE defining characteristic of an amphibian? - PowerPoint PPT PresentationTRANSCRIPT
Reptiles, Mammals, and Birds
Reptiles, Birds, & Mammals
Amphibians
~400 MYA
Early Reptiles: Reptilomorphs
• The earliest ancestors of reptiles are reptile-like amphibians.
• Remember: what is THE defining characteristic of an amphibian?
• The first “amphibian” that laid eggs on land… that’s our first reptile.
AMNIOTES: Reptiles, Mammals and Birds• An amnion is the
membrane “sac” in which an embryo develops.
• Labeled 2
• Both egg-laying and live-birthing animals may have an amnion
Reptiles: What is a Reptile?• Includes lizards, snakes,
crocodiles, turtles, and similar species.
• Aerobic, ectothermic amniotes with scales.
• The Komodo dragon (pictured) is the largest living reptile – it can grow to over 10 feet.
Oviparous Animals Lay Eggs
• For land-dwellers, fertilization is internal.
• Almost all embryonic development happens inside the egg.
Dinosaurs: Famous Reptiles
• The group of reptiles from which all true dinosaurs evolved includes crocodiles as well as ostriches…
• Appear around 250 MYA, during the Triassic period of the Mesozoic Eon… and some survive today!
Mammal-like Reptiles• Cynognathus (shown) is an example of one of
several fossil species that show divergence from the reptile line.
• The first true mammals (with mammary glands, fur, etc.) arise in the Triassic, about 200 MYA.
More about
mammals tomorrow
…
Class Aves: For The Birds
• Birds are close relatives to the dinosaurs
• This bird is preening – a feather cleaning activity that keeps them working just right.
Birds = Surviving Therapod Dinosaurs• Wishbone• Hollow bone structure• 3-toed foot• Oviparous and brooding (nesting)
What’s a Bird?
• Wings, two legs• Endothermic• Oviparous
• Modern birds all have:– Feathers– Toothless beak– Hard-shelled eggs– 4 chambered heart– Hard endoskeleton