BIOL 101 Exam 4 Learning Objectives

lect 22-27 prof. ekdale sdsu

What was Archaeopteryx?

Key transitional fossil b/c it exhibits a mix of dinosaurian traits: "long bony tail and teeth" with avian traits: "asymmetric flight feathers" and a furcula

If forelimbs of birds are modified for flying, how do they catch food?

They catch food using specialized beaks/bills (their jaws), beak structure is highly adapted to the bird's diet

Discuss wing mechanics (how do they work?)

Wings function as airfoils, lift is generated and maintained by cross-sectional area + constant angle of attack adjustment, the wings act directly forcing air over wing surface - prevents stalling at low speeds, the down stroke generates power while the up stroke slips directly past air

Discuss the origin of flight

"Ground-Up" hypothesis suggests that ancestors developed speed in their hind limbs and used forelimbs lengthened for grasping prey, feathers on forelimbs already present would provide lift

Which features of birds are adaptation(s) for flight and which are exaptation(s)?

Adaptations (evolved specifically for flight): keeled sternum, furcula (wishbone), and flight feathers; Exaptations (pre-existing traits co-opted for flight): feathers (originally for thermoregulation) and hollow bones (co-opted for the respiratory system)

Describe the unique method of respiration employed by birds

Birds use unidirectional airflow and two breath cycles, the rigid lungs use air sacs (posterior and anterior) to pump air, the flow ensures "stale air pushed out of trachea" and "fresh air pushes into lungs from posterior sacs" in a two-part inhalation and two-part exhalation process

Identify and discuss the major synapomorphies of mammals

Mammary glands (produce milk); Hair or fur (for insulation and sensory input); Three middle ear bones (malleus, incus, stapes); Diphyodont and heterodont dentition; Single dentary bone in the lower jaw

Distinguish between Polyphyodont/Diphyodont dentition

Polyphyodont: teeth are continuously replaced throughout life (most non-mammalian vertebrates); Diphyodont: only two sets of teeth in a lifetime (characteristic of most mammals)

Distinguish between Homodont/Heterodont dentition

Homodont: all teeth are of similar shape and size (dolphins); Heterodont: teeth are differentiated into specialized types (incisors, canines, premolars, molars) to perform different functions (characteristic of most mammals) How can the teeth of a mammal inform us about diet?

Discuss the evolutionary origins of the middle ear bones

The three mammalian middle ear bones evolved from bones of the ancestral synapsid lower jaw, the Malleus evolved from the articular bone and the Incus evolved from the quadrate bone, this transition shows jaw

Identify the major clades of mammals

Monotremes (Prototheria: egg laying); Marsupials (Metatheria: pouched); Placental Mammals (Eutheria: with a long gestation)

Distinguish between Oviparous/Viviparous

Oviparous: lays eggs (Monotremes); Viviparous: bears live young (Marsupials and Placentals)

Distinguish between Altricial/Precocial

Altricial: young are born underdeveloped and dependent (most marsupials and rodents); Precocial: young are born developed and self-sufficent

Identify the members of Theria

Theria is the clade containing Marsupials and Placental Mammals, they are viviparous (live birth) and have external nipples

What is a placenta?

A placenta is a circulatory and respiratory organ that connects the embryo to the mother for nutrient exchange, formed by embryonic membranes and the uterine wall What are pinnae and which mammals have them?

What is a marsupium and which mammals have one?

A marsupium is the external abdominal pouch where young are nursed, characteristic of most Marsupials

Compare gestation and lactation times between marsupials and placentals

Marsupials have a short gestation (birth is early) and a long lactation period (development is completed in the pouch); Placentals have a long gestation (fetus develops extensively in utero) and a relatively shorter lactation period

What is the only marsupial native to San Diego?

Virginia Opossum

Discuss the advantage of delayed implantation in kangaroos

Delayed implantation allows the female kangaroo to maintain an embryo while an older young is nursing in the pouch, this allows her to quickly resume gestation when the environment is favorable or the older young leaves, maximizing reproductive output

What is/ was a thylacine?

The thylacine ("Tasmanian Tiger") was a large carnivorous marsupial, now considered extinct since 1936

What type of placentas do placental mammals have, and how do they differ from marsupials?

Placental mammals develop a complex chorioallantoic placenta which fully implants and provides efficient, long-term exchange; Marsupials use a simpler, transient yolk sac placenta that results in a short gestation

What does it mean to be edentulous? Examples?

Edentulous means lacking teeth, anteaters What is the largest land animal?

Identify members of Afrotheria, Xenarthra, and Boreoeutheria (generally)

Afrotheria: originated in Africa, includes elephants, manatees, hyraxes, aardvarks; Xenarthra: originated in South America, includes sloths, anteaters, and armadillos; Boreoeutheria: includes most mammals of the N Hemisphere, the remaining placentals (rodents, primates, carnivores, whales, hoofed mammals)

Describe the wing of the only flying mammal. (What is that mammal, by the way?)

The only flying mammal is the bat (clade Chiroptera). The wing is a membrane (patagium) stretched between the elongated finger bones, arm and body

What is the most speciose clade of placental mammal?

the most speciose clade is Rodentia (Rodents)

Discuss the impact on humans that rodents have

Rodents have negative impacts on humans, incl destruction of food, structural damage from gnawing, and spreading disease

What is the difference between horns and antlers?

Horns (e.g., cattle) have an inner core of bone covered by a permanent, non-shedding outer sheath of keratin; Antlers (e.g., deer) are solid bone and are shed and regrown annually

What is the difference between rhino horns and cattle horns?

Rhino horns are made solely of keratin; Cattle horns have an inner core of bone covered by a permanent, non-shedding outer sheath of keratin

What are the two clades of completely aquatic mammals, and what are their closest relatives?

Cetacea (whales, dolphins, porpoises), closest relatives are the Artiodactyla (even-toed ungulates) specifically the hippos; Sirenia (Manatees, Dugongs), closest relatives are the Afrotherians (elephants and hyraxes)

List and discuss the synapomorphies of Primates

Grasping hands and feet w/ opposable thumbs/toes and flat nails; Forward-facing eyes (binocular/stereoscopic vision); Large brain size; Well-developed parental care and social behaviors

Which primate is the closest living relative of humans?

Chimpanzees and Bonobos (Our sister taxon)

Identify the importance of Homo habilis and Homo sapiens

Homo habilis (handy man): earliest Homo species, associated with the first simple stone tools (scrapers and hand axes) and an enlarged brain; Homo sapiens (wise man): the only extant hominin, characterized by fully modern anatomy, complex culture, and global distribution

How old are the oldest Homo sapiens fossils? (I.e., how old is our species?)

The oldest fossils from Ethiopia which provide evidence for the origin of Homo Sapiens in Africa, date to around 200,000 years ago

Place the following events in order: bipedal stance, large brain, speech

1. bipedal stance (4–7 mya, earliest derived human character); 2. large brain (2.5 mya); 3. complex speech (achieved later in Homo sapiens w/ vocal structures positioned lower in the throat)

What does it mean that you are a primate, mammalian, synapsid, amniote, tetrapod, sarcopterygian, osteichthyan, gnathostome, vertebrate, chordate, deuterostome, bilaterian, animal?

Primate (grasping hands), Mammalian (hair, glands), Synapsid (skull w/ one opening), Amniote (protective egg), Tetrapod (four limbs), Sarcopterygian (fleshy-limbed), Osteichthyan (bony skeleton), Gnathostome (jaws), Vertebrate (backbone), Chordate (notochord), Deuterostome (anus forms first), Bilaterian (bilateral symmetry), Animal (multicellular, heterotrophs, eukaryotic)