The Animal Kingdom Reptiles Birds Phylum Chordata Review
The Animal Kingdom Reptiles & Birds
Phylum Chordata Review branch points in animal evolution. 1 st = presence of tissues 2 nd = symmetry 3 rd = type of body cavity – a coelom Acoelomate: Sponges, Cnidarians, Flatworms. Coelomate: Nematodes, Annelids, Mollusks, Arthropods, Echinoderm 4 th = embryonic development Protostomes (blastopore becomes stomach): Mollusks & Arthropods. Deuterostomes (blastopore becomes anus): Echinoderms, Chordates
Phylum Chordata Chordates Possess all the characteristics of animals farther down on the evolutionary ladder: nucleus, multicellular, heterotrophic. Possess tissues, Bilateral symmetry, A coelom, and A deuterostome.
Phylum Chordata includes 3 subphyla: the urochordates, cephalochordates, & vertebrates. All share 4 anatomical structures at some point in life. A notochord A dorsal nerve cord Pharyngeal gill slits A post-anal tail
Vertebrates An overview of vertebrate diversity. At the base: hagfishes & lampreys which lack hinged jaws. All others have true jaws & paired appendages. In fishes, paired appendages function in swimming. In tetrapods, the appendages become legs. Amphibians lay eggs in water or a moist environment. Others are amniotes; producing shelled, water-retaining eggs allows them to complete their life cycles on land. Ex: reptiles and birds. In mammals, offspring develop internally.
Amniotes Evolution of an amniotic egg expanded success on land. This group consists of reptiles, birds, & mammals. The amniotic eggs enabled terrestrial vertebrates to complete their life cycles entirely on land. Most amniotic eggs have a shell that retains water and can be laid in a dry place. Reptiles, birds, & mammals also have water-tight skin. 4 -chambered heart.
Class Reptilia Reptiles became the dominant terrestrial vertebrates for more than 200 million years during the Mesozoic. Oldest fossils date to Carboniferous period, 300 mya.
Class Reptilia Reptiles became the dominant terrestrial vertebrates for more than 200 million years during the Mesozoic. Water-tight skin and eggs adapted them to life on Pangaea.
Class Reptilia Many groups of reptiles have gone extinct, but the main groups today are the turtles, snakes, and lizards, and crocodilians. The birds evolved from dinosaurs. Note mammals share a common ancestor with reptiles.
Class Reptilia There were two dinosaur lineages: Ornithischians were herbivorous (below left). Saurischians were both herbivorous and carnivorous. Included the ancestors of birds (below right).
Class Reptilia Argentinosaurus huinculensis 100 feet tall; 98 to 115 feet long; 75 tons; 5 mph.
Class Reptilia Signs of parental care among some dinosaurs. Debate about whether dinosaurs were endothermic. Some anatomical evidence supports this hypothesis. The dinosaurs that gave rise to birds were endothermic, as are all birds.
Class Reptilia Pterosaurs First flying tetrapods. One species had a wingspan up to 45 feet – the largest creature ever to fly (it probably glided).
Class Reptilia By the end of the Cretaceous (65 mya), dinosaurs had become extinct.
Class Reptilia There about 6, 500 species of reptiles today, classified into four orders: Testudines (turtles & tortoises); Sphenodontia (tuataras); Squamata (lizards, snakes); & Crocodilia (alligators & crocs).
Class Reptilia Order Testudines: turtles and tortoises Turtles are water-dwelling; tortoises are landdwelling. They haven’t changed since the Mesozoic era. A hard shell is an adaptation against predators.
Class Reptilia Order Squamata: Lizards and snakes Lizards are the most numerous & diverse reptiles alive now. They decrease their activity during cold periods, this may have enabled them to survive the Cretaceous “crunch”.
Class Reptilia Order Squamata: Lizards and snakes Snakes descended from lizards that adapted to a burrowing lifestyle through loss of limbs. Have no ears. Snakes are carnivorous; some are poisonous. Loosely articulated jaws let them swallow prey larger than their diameter.
Class Reptilia Order Crocodilia: Crocodiles and alligators Among the largest living reptiles; confined to the tropics and subtropics. Four chambered heart; aquatic.
Class Reptilia Order Sphenodontia: Tuataras 2 species found only in New Zealand; terrestrial.
The Animal Kingdom Birds
Class Aves Birds began as feathered reptiles beginning in the Jurassic Period.
Class Aves The closest reptilian ancestors of birds were theropods: small, bipedal, carnivorous dinosaurs (like the velociraptors). The most famous Mesozoic bird is Archeopteryx, an extinct side-branch of birds.
Class Aves Besides amniotic eggs & scales, modern birds have feathers and other distinctive flight equipment. Almost every part of a typical bird's anatomy is modified in some way to enhance flight. Ex: females have one ovary. Their skeletons are light and flexible, but strong. Bones are honeycombed to reduce weight.
Class Aves In addition to amniotic eggs and scales, modern birds have feathers and other distinctive flight equipment. Wings are airfoils. Pressure differences created by differences in air flow over the top and bottom of the convex wing lift it and the bird.
Class Aves In addition to amniotic eggs and scales, modern birds have feathers and other distinctive flight equipment. Flying requires a great expenditure of energy. Birds are endothermic, using their metabolic heat to maintain a constant body temp. Efficient resp. & circ. systems with a 4 chambered heart.
Class Aves In addition to amniotic eggs & scales, modern birds have feathers & other distinctive flight equipment. Lungs are like sponges; air sacs act as bellows, powered by flying muscles, so lungs never deflate – hold air constantly.
Class Aves In addition to amniotic eggs & scales, modern birds have feathers & other distinctive flight equipment. Feathers and fat provide insulation. Made of the keratin, like reptile scales & mammalian hair.
Class Aves In addition to amniotic eggs & scales, modern birds have feathers & other distinctive flight equipment. Birds have downy feathers and contour feathers. Downy feathers produce a fluffiness that provides insulation. Contour feathers are the stiff ones that contribute to the aerodynamic shapes of the wing and body.
Class Aves In addition to amniotic eggs & scales, modern birds have feathers & other distinctive flight equipment. Flight enhances hunting and scavenging, and escape. It enables many birds to migrate great distances to exploit different food resources and seasonal breeding areas.
Class Aves 8, 600 living bird species are classified in ~28 orders. Flightless birds (ratites) lack a breastbone & large pectorals. Include the ostrich, kiwi, and emu.
Class Aves 8, 600 living bird species are classified in ~28 orders. Most birds are carinates: have a carina, or sternal keel to anchor the large pectoral muscles.
Class Aves 8, 600 living bird species classified in ~28 orders. ~ 60% of bird species are in the order Passeriformes, or perching birds.