CH 34

About how long ago did modern humans evolve (really rough estimate here).

6.5 mya

Are all chordates vertebrates?

No, because some chordates don't develop a backbone

Distinguish between Old World and New World monkeys.

Old World- Africa and Asia. Non prehensile tails. New World- South America. Arboreal, prehensile tails that help for swinging

What seems to be the general evolutionary trend in hominin species?

bipedalism and brain growth

Describe key adaptations of aquatic gnathostomes.

1. jaws 2. paired fins and tail for swimming 3. streamlined bodies 4. swim blader/ oily liver

In addition to a bony skeleton, what other key adaptations characterize the bony fishes?

A protective flap called the operculum that covered the chamber of gills and a swim bladder that helps them stay buoyant.

What class do amphibians belong to? What types of animals belong to this clade?

Amphibia. Frogs, salamanders, and caecilians.

Describe the adaptations of amphibians, reptiles, and mammals to life on land.

Amphibians are not fully adapted to life on land, they must live near water in order to survive. Reptiles have adapted to life on land with their lungs, even if they are living in water, they must come to the surface to breathe.

How can amphibians be distinguished from reptiles?

Amphibians do not have scales, they breathe through their skin and need to stay near water to survive.

"Amphibian" comes from the Greek word amphibios, which means "living a double life." Briefly explain why this is an accurate term to call these organisms.

Amphibians go through metamorphosis. In their larval stage they are fully aquatic with gills and a tail, in the tadpole stage they develop legs and lungs as well as eardrums and a carnivorous digestive system.

Distinguish between the major characteristics of amphibians, reptile, birds, and mammals.

Amphibians- slimy skin, lay eggs in water. Reptiles- scales lay eggs on land. Birds- feathers, fly. Mammals- fur and produce milk.

Which trait (larger brains or bipedalism) evolved in hominins first? What evidence supports this theory?

Bipedalism. Lucy.

Briefly describe the evolutionary origin of birds. Explain how birds are adapted for flight.

Birds evolved from a two-legged dinosaur called theropods, they have honeycombed bones, only one ovary, small gonads, no urinary bladder, lack teeth, wings, and keratin feathers.

What do scientists hypothesize might have been the original function of feathers?

Camouflage, insulation, or for mating purposes.

What clade do the cartilaginous fishes with jaws belong to? What types of fish belong to this clade?

Chondrichthyes. Sharks, skates, rays, sawfishes, and chimaeras.

Oviparous

Eggs hatch outside the mother's body

Briefly describe the characteristics of the two lineages of jawless vertebrates.

Hagfish have a cartilaginous skull, reduced vertebrae, and a flexible rod of cartilage derived from the notochord. Lampreys are parasitic and have a notochord and cartilaginous skeleton.

Which species of hominin was the first to extend humanity's range outside of Africa?

Homo erctus

The earliest fossils showing evidence of tool use in hominins belonged to which hominin species?

Homo halibis

Describe the adaptations reptiles have for living on land.

Keratinized skin and scaled to create a waterproof barrier, and shelled eggs to live on land.

Describe three key amniote adaptations for life on land.

Keratinized skin, larger lungs, rib cage to ventilate the lungs.

What are apes? What are the distinguishing characteristics of apes?

Larger than monkeys, long arms, short legs, no tail, highly social, large brains.

List the three main groups of primates.

Lemurs, lorises, and bush babies

What clade do mammals belong to? Describe the derived characteristics common to all mammals.

Mammalia. Mammary glands (produce milk), hair (insulation and warmth), endothermy (high metabolic rate), large brain, parental care.

Distinguish between monotremes, marsupials, and eutherian mammals.

Monotremes are small egg-laying mammals consisting of echidnas and the platypus, the females lack nipples and secrete milk from glands on their bellies; the baby sucks milk from the mother's fur. Marsupials include opossums, kangaroos, and koalas. The embryo develops within the mother's utuerus and is nourished by the placenta, is born very early in development and nurses in its maternal pouch. Eutherian mammals have a complex placenta and complete their embryonic development within the uterus.

Why are most marsupials found only in Australia?

Pangea had Australia isolated for 66 million years.

Describe the derived characters of primates.

Primates evolved from insect eating mammals during the late Cretaceous period 65 mya, they were tree-dwellers which explains their hands and feet adapted for grasping. They also have limber shoulder joints for swinging amongst branches, a large brain and short jaws, forward looking eyes for depth perception, complex social behavior and parental care, and opposable thumbs.

What two clades of fish have a bony skeleton?

Ray-finned and lobe finned fishes.

Which groups of vertebrates are considered to be amniotes?

Reptiles and mammals.

What class do reptiles and birds belong to?

Reptilia.

Briefly describe the adaptations of sharks that are responsible for their success as marine predators.

Sharks are successful predators because their dorsal fins provide stabilization and their paired pectoral and pelvic fins are used for maneuvering, their continual swimming keeps sharks from sinking and maintains continuous flow of water over gills, and their oily liver helps them maintain buoyancy.

What key characteristic distinguish diapsids and synapsids?

Synapsids have one skull opening and were mammalian ancestors, diapsids have a pair of openings and are reptilian ancestors.

Describe the origin of tetrapods and identify some of their key derived traits.

Tetrapods were the first lobe finned fishes to evolve the fins into limbs and feet. They have four limbs, a neck for movement, fusion of pelvic girdle to backbone, absence of gills, ears for detecting airborne sounds.

Briefly describe how the amniotic egg enables life on land.

The amniotic egg has a shell that protects the embryo from predators and pathogens and can be laid on land, hence cutting the amniotes dependence on the water for offspring.

Explain the evolutionary trade off associated with the amniotic egg adaptation.

The evolutionary trade off associated with amniotic eggs is that less eggs can be produced because more parental care is needed to ensure offspring survival, so the amount of offspring and parental involvement was traded.

What features do lobe-finned fish have that distinguishes them from ray-finned fishes?

The fins of lobe-finned fishes differ because they're borne on a fleshy, lobelike, scaly stalk extending from the body.

List the four key characteristics of chordates. Briefly describe the function of each of these characteristics.

The four key characteristics of chordates are the notochord, dorsal, hollow nerve chord, pharyngeal slits, and muscular, post anal tail. The notochord provides skeletal support throughout most of the length of the chordate. The dorsal, hollow nerve chord develops into the central nervous system: brain and spinal cord. The pharyngeal slits are for suspension feeding. The tail provides propelling force in aquatic species.

Which two lineages of vertebrates lack jaws?

The hagfishes and the lampreys.

Briefly describe the evolution and significance of the jaw.

The jaw evolved from the first gill bar which became hinged.

What was the original function of the jaw

The jaw was originally for respiration, but movement of the jaw created a current of water through the mouth and over the gills.

What is the significance of the neural crest?

The neural crest pinches off the ectoderm during embryonic development.

Briefly describe the evolutionary origin of mammals.

They were small nocturnal insect eaters, synapsids which created the middle ear.

Which two groups of chordates are invertebrates?

The two groups of chordates that are invertebrates are the urochordates and cephalochordates.

What features distinguish bony fish from sharks?

Their skeleton, bony fish skeleton's are made of bone, cartilaginous fish (sharks) skeleton's are made up of cartilage.

Why do amphibians have slimy skin?

Their skin is slimy for gas exchange.

What is interesting about Homo neanderthalensis and Homo sapiens?

There is suggested interbreeding between Neanderthals and some populations of Homo sapiens, roughly 2% of the genomes of most present-day is similar to Neanderthal genome,

What are some unique traits of H. sapiens that contribute to the evolutionary success of humanity?

They were the first group to show evidence of symbolic and sophisticated thought with cave paintings

What characteristics distinguish humans from other apes?

Upright posture and bipedal locomotion, larger brains, capable of language, symbolic thought, artistic expression, use of complex tools, reduced jawbones and jaw muscles, shorter digestive tract

Explain the misconceptions that (a) chimpanzees are our ancestors, (b) human evolution is a ladder.

a) Chimps and humans share a common ancestor, we are not derived from apes. b) Hominin evolution included many branches of coexisting species, only the humans survive today.

What are the three surviving lineages of lobe-fins.

coelacanths (Actinistia), lungfishes (Dipnoi), and tetrapods

How do amphibians reproduce?

external fertilization in water, because they are shell less.

What derived characters do sharks and bony fish share?

gills, idk man.

viviparous

live birth

What group of fishes shares a common ancestor with tetrapods?

lobe-finned fishes

Ovoviviparous

producing living young from eggs that hatch within the body

What is the function of vertebrae?

protect spinal cord

What is unique about the vertebrate brain?

segmentation of the hindbrain into 3 major regions: the hindbrain, the midbrain, and the forebrain.