Archaeopteryx.html: 34_29Archaeopteryx.jpg
Artist?s reconstruction of Archaeopteryx, the earliest known bird. Fossil evidence indicates that Archaeopteryx was capable of powered flight but retained many characters of nonbird dinosaurs.

amniotes.html: 34_23AmniotePhylogeny.jpg
Amniotes comprise

• Diapsids (including birds) and other reptiles,
• Synapsids.

amniotic.html: 34_24AmnioteEgg.jpg
The amniotic egg contains several membranes that allowed animals to live a fully terrestrial life style.

• The allantois holds metabolic wastes produced by the embryo.
• The chorion and the allantois exchange gases between the embryo and the air.
• The amnion protects the embryo in a fluid-filled cavity that serves as a cushion.
• The yolk sac provides nutrients via blood vessels; other nutrients are stored in the albumen (egg white).

amphibia.html: 34_21AmphibianDiversity.jpg

Class Amphibia.
Order Urodela. Urodeles (salamanders) retain their tail as adults.		Order Anura. Anurans, such as this poison arrow frog, lack a tail as adults.		Order Apoda. Apodans, or caecilians, are legless, mainly burrowing amphibians.

amphibian.html: 34_22FrogLifeStages.jpg
Amphibia lead “two ways of life”. Fertilization is external, and the eggs require a moist environment. Aquatic larva undergo metamorphosis into a terrestrial adult. Most amphibians have moist skin that complements the lungs in gas exchange

art.html: 34_45Art.jpg
Art, a human hallmark. The engravings on this 77,000–year–old piece of ochre, discovered in South Africa's Blombos Cave, are among the earliest signs of symbolic thought in humans. _Vid_Johnson4e/Wmv/Alex_the_Talking_Parrot.wmv

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Australopithecus, an early hominid.

1. Lucy, a 3.24-million-year-old skeleton, represents the hominid species Australopithecus afarensis.
2. The Laetoli (Tanzania) footprints, more than 3.5 million years old, confirm that upright posture evolved quite early in hominid history.
3. An artist’s reconstruction of what A. afarensis may have looked like.

birds.html: 34_30BirdDiversity.jpg

Emu. This Australian ratite has no keel on its sternum and cannot fly.		Like many bird species, the mallard exhibits pronounced sexual dimorphism between the sexes.		Like most birds, Laysan albatrosses have specific mating behaviors, such as this courtship ritual. (hint)		The barn swallow is a perching bird (order Passeriformes ); its toes can lock around a branch or wire, enabling them to rest in place for long periods.

birdwing.html: 34_28WingStructureFunct.jpg
(a) A wing is a remodeled version of the tetrapod forelimb. (b) The bones of many birds have a honeycombed internal structure and are filled with air. (c) A feather consists of a central air–filled shaft, from which radiate the vanes. The vanes are made up of barbs, which bear small branches called barbules. Birds have contour feathers and downy feathers. Contour feathers are the stiff ones that contribute to the aerodynamic shapes of the wings and body. Their barbules have hooks that cling to barbules on neighboring barbs. When a bird preens, it runs the length of each contour feather through its bill, engaging the hooks and uniting the barbs into a precise shape. Downy feathers lack hooks, and the free–form arrangement of their barbs produces a fluffiness that provides insulation by trapping air.

chondrichthyes.html: 34_15ChondrichDiversity.jpg

Chondrichthyes have a skeleton made of cartilage.
Blacktip reef shark (Carcharhinus melanopterus). Fast swimmers with acute senses, sharks have paired pectoral and pelvic fins.		Southern stingrays (Dasyatis americana) are bottom-dwellers that crush molluscs and crustaceans. Manta rays cruise in open water and scoop food into their gaping mouth.		Spotted ratfish (Hydrolagus colliei) feed on shrimps, molluscs, and sea urchins. Some species have a poisonous spine at the front of their dorsal fin.

chordata.html: 34_02ChordatePhylogeny.jpg
Phylum chordata, including humans, are bilateral animals that belong to the clade Deuterostomia. Vertebrates are a subphylum within Chordata that possess a vertebral column (backbone).

chordate.html: 34_03ChrodateCharacters_L.jpg
Phylum chordata are animals that possess:

• a flexible notochord
• a dorsal, hollow nerve cord
• pharyngeal slits or clefts
• a muscular, post-anal tail

coccyx.html: Vertebral_column.jpg

coelacanth.html: 34_18Coelacanth.jpg
Coelacanth (Latimeria) are lobe–fins that live in deep ocean, and were thought to be extinct until discovered in 1938. They are the closest link between fish and the tetrapods that colonized land.

craniate.html: 34_07NeuralCrest_L.jpg
Craniates have a head, which is derived from ectodermal cells called the neural crest.

crayfish.html: 34_crayfish_bottom.gif

crocodilian.html: 34_27ReptileDiversityE.jpg
Crocodilians exhibit temperature-dependent sex determination: high nest temperatures produce male offspring. They also show some parental care by guarding the nest and defending their young.

egg.html: 34_25HatchingReptile.jpg
These bushmaster snakes (Lachesis muta) are breaking out of a parchment–like shell, a common type of shell among living reptiles other than birds.

hagfish.html: 34_09Hagfish_LP.jpg
Hagfish can produce copious amounts of slime, which they clean off by tying themselves in a knot.
_WMV_Hagfish.wmv

hominoids.html: 34_40HominoidDiversity.jpg
Hominoids (or apes) include:

1. gibbons
2. orangutans
3. gorillas
4. chimpanzees
5. bonobos.

homo_erectus.html: 34_43HomoErectus.jpg
Homo erectus originated in Africa 1.8 million years ago. It was the first hominin to leave Africa.

homo_ergaster.html: 34_43HomoErgaster.jpg
Fossil and artist's reconstruction of Homo ergaster. This 1.7–million–year–old fossil from Kenya belongs to a young male Homo ergaster. This individual was tall, slender, and fully bipedal, and he had a relatively large brain.

homo_habilis.html: 34_43HomoHabilis.jpg
Homo habilis lived about 2.4 to 1.6 million years ago, and made stone tools.
Its name means “handy man”.

homo_neanderthalensis.html: 34_43HomoNeanderthalensis.jpg
Homo neanderthalensis lived in Europe and the Near East from 200,000 to 30,000 years ago. There may gave been limited gene flow between Neanderthals and H. sapiens before the former became extinct.

jaw.html: 34_13JawEvolution.jpg
The evolution of vertebrate jaws.
The skeleton of the jaws and their supports evolved from two pairs of skeletal rods (red and green) located between gill slits near the mouth.

lancelet.html: 34_05Lancelet.jpg
The lancelet displays all four main chordate characters: a flexible notochord, a dorsal, hollow nerve cord, pharyngeal clefts, and a muscular, post-anal tail. The notochord provides support for segmented muscles that allow wavelike swimming movements.

lateral_line.html: 34_sardine.jpg
The lateral line allows fish such as sardines to sense vibrations in the water and change directions in synchrony.

lizard.html: 34_27ReptileDiversityB.jpg
There are over 4,000 species of extant lizards, making them the most diverse reptiles, apart from birds. _Vid_Johnson4e/Wmv/Horned_Lizard_and_Coyote.wmv

lobe-finned.html: 34_19Acanthostega.jpg
Acanthostega from the Devonian period (365 MYA) had limb-like fins but also retained aquatic adaptations such as gills.
Tetrapods evolved from similar members of the bony fishes called Sarcopterygii (lobe-finned fishes).

lungfish.html: 34_lungfish.jpg
Lungfishes (order Dipnoi) have a modified swim bladder that allows them to breathe air.

mammalia.html: 34_MammalPhylogeny.jpg
Class Mammalia contains 20 orders of animals, including humans. Mammals possess hair (or fur) and produce milk from mammary glands.

mammals.html: 34_36MammalPhylogeny.jpg

mantaray.html: 34_mantaray.jpg
Manta Ray

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A young brushtail possum. The young of marsupials are born very early in their development. They finish their growth while nursing from a nipple in their mother’s pouch.		Long-nosed bandicoot. Bandicoots have rear-opening pouch to protect the young from dirt as the mother digs. Other marsupials, such as kangaroos, have a pouch that opens to the front.

marsupials.html: 34_35Marsupials.jpg
Marsupials belong to the Chordate class Mammalia that are born early and complete embryonic development within a maternal pouch (marsupium). Many marsupials in Australia resemble eutherians elsewhere that occupy similar ecological niches due to convergent evolution.

monkeys.html: 34_39Monkeys_LP.jpg

New World monkeys, such as spider monkeys (shown here), squirrel monkeys, and capuchins, have a prehensile tail and nostrils that open to the sides.		Old World monkeys lack a prehensile tail; their nostrils open downward. They include macaques (above), mandrills, baboons, and rhesus monkeys.

monotreme.html: 34_33Echidna.jpg
Short-beaked echidna (Tachyglossus aculeatus), an Australian monotreme.
Monotremes have hair and produce milk, but lack nipples and lay eggs. Milk is secreted by glands on the belly of the mother. After hatching, the baby sucks milk from the mother's fur.

nerve.html: Vertebrae.jpg
The nerve cord is a hollow tube comprising the central nervous system: the brain and a spinal cord enclosed by vertebrae.

notochord.html: 34_vertebra_discs.gif
The notochord is a stiff but flexible rod between the digestive tube and the nerve cord. In humans, it is reduced to gelatinous disks between the vertebrae.

oldestHSapiens.html: 34_44OldestHSapiens_UP.jpg
Oldest known fossil of Homo sapiens.
This skull differs little from the skulls of living humans.

osteichthyes.html: 34_16TroutAnatomy_L.jpg
Osteichthyes have a bony endoskeleton. They control buoyancy with a swim bladder, and breathe through gills covered by a protective bony flap called the operculum. A lateral line allows fish such as sardines to sense vibrations in the water and change directions in synchrony.

pharyngeal.html: 34_pharyngeal.jpg
Chordate embryos possess grooves (pharyngeal clefts) in the pharynx (region posterior to the mouth). Pharyngeal clefts develop into gills in fishes, and structures in the head, ear, and neck in terrestrial vertebrates.

pikaia.html: Cambrian/Pikaia.gif

primates.html: 34_37PrimatePhylogeny-L.jpg
Anthropoids began diverging from other primates about 50 million years ago. The human lineages branched off from other hominoids about 5 to 7 million years ago.

ray-finned.html: 34_17RayFinnedFishDivers.jpg
Actinopterygii (ray-finned fishes) have fins supported by bony spines ("rays"), which are adapted for maneuvering, defense, and other functions.

shark.html: 34_shark-anatomy.jpg

snake.html: 34_27ReptileDiversityC.jpg
Snakes evolved from lizards. Some snakes such as pythons and boas retain primitive limbs.

tail.html: Snake_skeleton.jpg
Chordates have a tail posterior to the anus. The tail contains skeletal muscles, and provides the propelling force in many aquatic species.

tetrapods.html: 34_20TetrapodOrigin_L.jpg
The origin of tetrapods. Tetrapods are terrestrial vertebrates with four legs. A great diversity of tetrapods emerged during the Devonian and Carboniferous periods.

tuatara.html: 34_27ReptileDiversityA.jpg

tunicate.html: 34_04TunicateStructure_CL.jpg

An adult tunicate, or sea squirt, is a sessile animal.		In the adult, prominent pharyngeal slits function in suspension feeding, but other chordate characters are not obvious.		A tunicate larva is a free-swimming but nonfeeding “tadpole” in which all four chief characters of chordates are evident.

turtle.html: 34_27ReptileDiversityD.jpg
The shell of turtles is made of an upper carapace and lower plastron. The vertebrae, clavicles, and ribs are fused to the carapace; the shoulders and pelvic bones are within the ribcage. This species is sold in pet shops, but not native to northern llinois.

vertebrae.html: 34_01SnakeSkeleton_UP.jpg
Vertebrae are made of a series of bones that make up the backbone and enclose the spinal cord.

vertebrate.html: ../ch32/32_06CambrianSea.jpg