bio ekdale exam 4 sdsu

Modern birds are descendants (and therefore members) of.(Hint: don't be fooled by the name!)

Saurischia ("lizard-hipped" dinosaurs)

All mammals produce milk for their young. However, there is one clade of mammals that lacks nipples or teats. (Rather, the milk is secreted onto the mother's skin, which is then lapped up by the baby.) Which mammal clade lacks nipples or teats?

Monotremata

Archaeopteryx likely was capable of powered flight on account of the presence of fossilized:

asymmetrical feathers

Raindrops on roses and whiskers on kittens are some of Dr. Ekdale's favorite things. What is another name for whiskers, or sensory hairs used for tactile (touch) sensations?

vibrissae

Based on the number of temporal openings (or "windows"), mammals have a(n) skull.

synapsid

What feature shared by archosaurs and mammals (but no other amniotes) allows those animals to breathe with a mouth full of food?

secondary bony palate

Holy cow, you climbed all the way to the tippy-top of Denali (also known as Mount McKinley), the tallest mountain in North America. Way to go! On your way down the mountain, you encounter a large and hairy amniote and two of her offspring that are suckling from a couple of their mother's six nipples. The mother, who has four limbs with long claws extending from its fingers and toes, stands on its two back limbs and growls at you. As she growls, you can feel her warm breath, despite the chilly mountain air. You also notice that she has two long, conical, piercing canines in front of a series of shorter, bumpy, crushing molars protruding from the single bone of her lower jaw. What type of animal have you encountered?

a placental or eutherian mammal

In marsupial mammals, the placenta is composed of the chorion and the:

yolk sac

While large-bodied dinosaurs are extinct, their living descendants are represented by:

birds (Aves)

A marsupium is a(n):

pouch in which young finish their development

secondary bony palate

bony separation of nasal and oral cavities (hard palate, roof of mouth) that allows an animal to eat and breathe at the same time.

furcula

fused clavicles (wishbone) found in many theropod dinosaurs, including living birds

From which specific reptilian lineage did modern birds descend? (Be as specific as possible.)

Modern birds (Aves) are descendants of the ancestor of:- Archosauria- Dinosauria- Saurischia- Theropoda.

List the two major living clades of Archosauria.

1. Crocodylia (crocodiles and alligators)2. Aves (birds)

List the synapomorphies shared by all archosaurs.

- a four-chambered heart- nest building and parental care- a secondary bony palate(Birds, which are most archosaurs, have endothermy and legs held under the body, but these are not found in crocodylians.)

A secondary bony palate is a feature shared by all archosaurs (and independently evolved in mammals). What does the secondary bony palate allow the animal to do, which might give it a natural selective advantage over other amniotes?

A secondary bony palate:- separates the nasal and oral cavities in archosaurs and mammals- allows the animals to eat and breathe at the same time.
(A potential selective advantage is that mammals and archosaurs would be able to consume more food than those without a secondary bony palate.)

Dinosaurs are divided into two groups: Saurischia ("lizard-hipped") and Ornithischia ("bird-hipped"). To which of these groups do living birds belong? (Hint: don't let the names fool you!)

Despite the meaning of the name ("lizard-hipped"), living birds (Aves) are descendants of saurischian dinosaurs, and thus are members of Saurischia.

Are the furcula ("wishbone"), hollow bones, and feathers adaptations or exaptations for flight? How do you know?

The furcula, hollow bones, and feathers are exaptations for flight, because all of those features evolved before flight (i.e., found in early dinosaurs that were incapable of flying).

What was Archaeopteryx?

the earliest bird from ~150 million years ago.

Briefly discuss the "Ground-Up" hypothesis for the origin of flight.

- argues that bird ancestors were adapted for running on the ground to chase prey.- The grasping motion of ground-dwelling theropods is similar to the flight stroke of flying birds, and feathers on those dinosaurs would give them a little lift during prey capture.- (This is the prevailing hypothesis for the evolution of flight.)

How does respiration in birds differ from respiration in mammals?

- in birds is unidirectional- in mammals is bidirectional.

Identify four potential causes for the extinction of non-avian dinosaurs approximately 66 million years ago.

- asteroid impact- volcanos- fall in sea level- climate change

What aspects of bird wings provide lift during flight?

- Asymmetrical feathers provide lift during flight, and well as the cross-sectional area and shape of the wings.- Asymmetrical feathers are a synapomorphy of Aves, although feathers in general are an exaptation that they inherited from their theropod ancestors
Lift: is created when air moves faster over the top of the wing than below the wing

The wings of birds are modified for flight. What part of their body is modified for feeding?

The snouts of birds are modified as beaks. (Variation in beaks indicates variation in diets and function)

Are archosaurs diapsid, synapsid, or anapsid reptiles?

Archosaurs are diapsid reptiles

diphyodont

two sets (generations) of teeth, found in most mammals

monophyodont

one set (generation) of teeth

homodont

type of dentition in which all teeth look the same

heterodont

type of dentition in which teeth are shaped differently for different functions

cloaca

shared orifice (opening) for the urogentical system and digestive system (anus)

vibrissae

sensory hairs (whiskers) for tactile sensation (sense of touch)

marsupium

pouch (characteristic of most marsupial mammals)

pinnae

external ear flaps

placenta

vascular structure for nutrient exchange between the mother and the developing embryo

edentulous

no teeth (seen in some xenarthrans and some cetaceans)

Mammals are amniotes. Based on the pattern of temporal openings, would you consider mammals to be anapsids, diapsids, or synapsids?

Mammals are synapsids with only one temporal opening

List the three major living clades of mammals. Which is the largest in terms of number of species?

- Monotremata- Marsupialia (Metatheria)- Placentalia (Eutheria)
Placentalia is the largest of the three clades. (Placentalia and Marsupialia both compose Theria.)

Which mammals belong to the clade Theria?

Theria (mammals that give live birth/ bear live young)
- includes Marsupialia (marsupials) and Placentalia (placentals; same thing as Eutheria)

List four synapomorphies that unite all mammals

- mammary glands (produce milk)- hair- single bone in the lower jaw (dentary)- three middle ear bones (ossicles).

In what ways are living mammals convergent with living archosaur reptiles? (I.e., what features evolved independently in Mammalia and Archosauria?)

Mammals and archosaurs possess:- secondary bony palates- 4-chambered hearts- endothermy
Those features are considered to be homoplasies, or similarities not based on common ancestry (but rather common function).

Distinguish between the three groups of living mammals based on reproduction. (I.e., oviparous versus viviparous; precocial versus altricial)

- Monotremes are oviparous (egg-laying) and altricial (born at an early stage of development), lay shelled amniotic eggs, but heldinside mother for a while for nutrient exchange- Marsupials are viviparous (live birth) and altricial (born at an early stage of development)- Placentals are viviparous (live birth) and precocial (born at a late stage of development)

Discuss the evolutionary origin of the mammalian middle ear. (I.e., what are the reptilian homologues of the ossicles - hammer [malleus], anvil [incus], and stirrup [stapes]?)

- The hammer (malleus) and anvil (incus) of the mammalian middle ear evolved from bones of the reptilian jaw- The stirrup (stapes) of mammals is homologous to that of reptiles.- (The evolution of the three middle ear bones in mammals is documented in the fossil record as well as in the embryonic development of living mammals.)

How do the urogenital openings of therian mammals differ from monotremes?

- Monotremes possess a cloaca (shared opening for the urogenital and digestive systems)- therians openings are separate (the anus is separate from the urogenital opening)- All mammals have copulatory organs and reproduce using internal fertilization, including both therians and monotremes.

How does the placenta differ between placental and marsupial mammals?

- in marsupial mammals: the placenta (vascular structure for nutrient exchange between the mother and the developing embryo) is derived from the chorion and the yolk sac, forming a "yolk sac placenta".- the embryo does not implant into the uterus; no maternal component to the yolk sac placenta
- In placental mammals, the placenta is derived from a fusion of the chorion and allantois, forming a "chorioallantoic" placenta.-Placental embryos implant themselves into the wall of the uterus; is a maternal component to the chorioallantoic placenta.)

How does gestation differ between placental and marsupial mammals?

in marsupials:- gestation is relatively short (young are altricial) followed by a prolonged lactation period.
in placentals:- gestation is long (young are precocial) followed by a relatively short lactation period.

What is the benefit of delayed implantation of the embryo in female kangaroos?

- "freezes" the development of an embryo- allows the mother kangaroo to have multiple offspring at different stages of development at the same time.

What is the only species of marsupial native to the northern hemisphere (including San Diego!)?

the Virginia (American) opossum (Didelphis virginiana).

What is/ was the thylacine?

- The thylacine (commonly known as the Tasmanian wolf or Tasmanian tiger)- was the largest carnivorous marsupial to have ever lived.- Unfortunately, the thylacine is now extinct (and has been since 1936).

What is the advantage of "playing possum"?

"Playing possum" is a defensive strategy in which an opossum will act like it is dead. This behavior discourages predators from eating it.

Cetaceans (dolphins and other whales) are exclusively aquatic, but they are descended from a terrestrial ancestor. From what terrestrial placental mammal group are cetaceans descended?

Cetaceans are descendents of Artiodactyla (and thus are derived artiodactyls themselves, much like birds are derived dinosaurs).

Identify the only mammalian clade capable of powered flight.

Chiroptera (bats)

Distinguish between antlers and horns.

Antlers (grown by deer and their relatives): are temporary structures that are shed and regrown annually.- Only males have antlers in most species.
Horns (grown by cattle): are permanent structures that are not shed, consisting of a horny sheath over a bony core.- Both males and females can have horns.

List the major synapomorphies of Primates.

- a large brain- forward facing eyes with depth perception (binocular vision)- well-developed parental care and complex social behaviors- grasping hands (opposable thumb in most)

Are chimpanzees more closely related to humans or to gorillas?

- chimpanzees are more closely related to humans than they are to gorillas.- humans are more closely related to chimpanzees than any other animal!)

Place the following events of human evolution in order from first (earliest, oldest, first to occur in time) to last (latest, youngest, last to occur in time): enlargement of the brain, speech, bipedal stance

1) bipedal stance2) enlargement of the brain3) speech

What is the evolutionary importance of Homo habilis? What about Homo sapiens?

Homo habilis: is the first member of our own genus, and likely the first of our ancestors to fashion tools (~2.5 million years ago).
Homo sapiens: is our own species (appeared ~200,000 years ago).

How old are the oldest Homo sapiens fossils?

The oldest Homo fossils (Homo habilis) are approximately 2.5 million years old.
The oldest Homo sapiens fossils (representing our own species) are ~200,000 years old.

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

Humans are descendents of the most recent common ancestor of the clades:- Primates (have big brains and binocular vision)- Mammalia (have hair and three bones in our ears)- Synapsida (have a single temporal opening)- Amniota (developed within an embryonic egg)- Tetrapoda (land animals with fingers and toes)- Sarcopterygii (have internal limb bones with elbows and knees)- osteichthyes (have air sacs developed as lungs)- Gnathostomata (have jaws)- Vertebrata ( bony vertebrae and a pineal gland/ organ)- Chordata (endostyle/ thyroid and dorsal nerve cord is hollow)- Deuterostomata (nerve cord is positioned dorsally)- Bilateria (bilaterally symmetrical)- Animalia (multicellular eukaryotes gain nutrition through ingestion)

primates

- are eutharian/placental animals

Which correctly describes phylogenetic relationships among birds, mammals, and reptiles?
A. Birds share the closest common ancestor with dinosaursB. Reptiles and birds, but not mammals, are amniotesC. Birds and mammals are more closely related to each other than either group is to reptilesD. Among living species in the group we call reptiles, crocodilians and lizards are most closely related to each other because they are "cold blooded"

A. Birds share the closest common ancestor with dinosaurs

What are the 4 potential causes of the extinction of dinosaurs?

- Asteroid impact- Volcanoes- Sea-level fall- Climate change

How does air flow through the respiratory system of birds?

In one direction (unidirectional air flow)

How would you characterize mammals based in temporal openings (windows in side of skull)?

Synapsid

True or False: All mammals are viviparous!

False

How does the placenta of marsupial mammals differ from that of placental mammals?

Fusion of chorion and yolk sac

What kind of mammal is the Megalonyx Jeffersonii?

A giant, ground sloth

What is the order in which upright stance, big brain and speech occurred/evolved in humans from first to last?

Upright stance -\> big brain -\> speech

what is the most diverse reptile?

squamata (lizards and snakes)

Synapomorphies of Squamata

- Forked tongue used to detect chemicals in the air("smell")- Hemipenes in males (paired copulatory organs); males alternate during copulations

what does Squamata mean?

"scaly"

what does Archosauria mean?

"lead lizard"

How many holes do Archosaurias have in their head?

they are diapsid reptiles

key synapomorphies of Archosauria

- Four chambered heart- Nest building and parental care- Secondary bony palate (2nd roof of mouth)- Endothermy (in bird vs. ectothermy in crocs) Some- Legs held under body (in dinosaurs)

endothermic vs. ectothermic

temperature regulators vs. temperature comforters

Nest building and parental care - what's the benefit?A) Enhances offspring survivalB) Allows more offspring to be produced

a. enhances survival of the offspring

what would be the benefit of a secondary bony plate?A) Allows animal to eat food items larger than itselfB) Allows animal to swallow larger preyC) Allows animal to eat and breathe at the same time

C) Allows animal to eat and breathe at the same time

All Crocodylia are?

- aquatic- carnivorous- have long, powerful snouts- oviparous- build nests and exhibit parental care

What do you call it when crocodyles lay in the sun? what type of body heat retention do they use?

shore basking & ectothermic

sauropods vs. theropods

sauropods: herbivores, some of the largest land animals
theropods: carnivores, gave rise to birds

what does dinosauria mean?

"terrible lizard"

In order to fly, birds must have which of the following adaptations?A. A lightweight skeletonB. Powerful chest musclesC. A highly efficient respiratory systemD. A high-pressure circulatory systemE. All of the choices are correct

E. All of the choices are correct

respiration in Birds

- Unidirectional through lungs- Gas exchange occurs in lungs, posterior and anterior air sacs act as bellows (no gas exchange)

inhalation vs. exhalation

- Inhalation:Fresh air brought into lungs- Exhalation:Stale air pushed out of lungs through windpipe (trachea)

mammary glands

- Modified sweat glands- Delivered to young via nipples (teats) in placentals and marsupials; no nipples in monotremes, rather milk released onto surface of skin and is lapped upAll mammals produce milk, but not all have nipples

aposematic coloration

defensive warning signalex: skunks

what are Echidnas? what are there characteristics?

- "spiny anteaters"- Lay eggs (oviparous), eggs hatch after 10 days- Young born altricial (early)- Milk is secreted from mammary glands (no nipple or teat)- Long claws (for digging), long snouts & tongues (insectivorous)- Hair modified as spines (defense)

What is the clade Theria?

-Includes marsupials and placentals- External ear flaps ("pinnae") areprominent in most species- All therians are viviparous- Cloaca is lost, therians have separate urogenital openings- Males have external gonads- Milk delivered to young via nipples- Embryo is connected to mother via a placenta, connects embryo to mother for nutrient exchange

Three major clades of Placentalia

- Afrotheria (elephants, manatees, hyraxes, aardvarks)- Xenarthra (anteaters, armadillos, sloths)- Boreoeutheria (rodents, rabbits, carnivores, bats, whales, hoofed mammals, primates)

what is the clade Afrotheria?

- Mammals that originated in Africa• Proboscidea-elephants (Africa and Asia; extinct species in Europe and North America)• Sirenia - manatees and dugongs (coastal habitats)• Other species - aardvarks (Africa only), hyraxes (Africa only), tenrecs (Africa only)

what is Proboscidea?

- elephants- all herbivorous- two upper incisors modified as tusks- Big ears used for thermoregulation (large surfaces for heat loss)- Trunk allows the animals to smell the ground without bending over (as well as used as an appendage)- trunk is muscular (no bones)

what is Sirenia

- manatees• Lack hind limbs• Forelimbs are flippers, tail is a fluke • Strictly herbivorous• Very docile; easily injured by boats- body covered in vibrissae

impacts of clade Rodentia on humans

- Disease: plague, Hanta virus- Structural damage from gnawing-Destruction of food: up to 30% of human food is destroyed by rodents in developing countries

what is clade Cetacea?

- whales- Dolphins, porpoises,whales

Characteristics of Cetacea

- Exclusively aquatic (hind limbs lost; tails modified as flukes)-Terrestrial ancestry well- documented (from terrestrial artiodactyls)

what are the two major groups of Cetacea?

• Odontocetes (toothedwhales)• Mysticetes (baleen whales)

Where are prehensile tails only found at?

South American monkeys

Three Primate Lineages

- Lemurs & Lorises- Tarsiers- Anthropoids (monkeys, apes, humans)

Derived characters of Humans

• Stance - near bipedalism maybe 4.4 mya("Australopithecines")• Brain - enlargement, early Homo, 2.4 myaand tool use and manufacture-oldest evidence 2.5 my• Speech - possibly near origin of modern humans, 200,000 yrs ago(1) requires brain that can formulate and understand language(2) vocal power and control(3) sensitive hearing (chimps did not achieve 2)

What do the hollow bones in birds

May lighten the skeleton for flying, but really part of respiratory system

What do flight in birds do? benefits vs. cons?

- flight is an unoccupied niche that birds fill- increases travel ability (benefit)- increases energetic needs (cost)