Exam Review PDF

# Exam Review ## Lesson 14 - **Pelycosaurs → Therapsids → Cynodonts → Mammals** - **Basal Synapsids: Pelycosaurs** - Reptiles that arose in the Carboniferous before lineage that led to modern mammals. - Single temporal fenestrae (like modern mammals vs ancestor reptile lineage that had 2)...

# Exam Review ## Lesson 14 - **Pelycosaurs → Therapsids → Cynodonts → Mammals** - **Basal Synapsids: Pelycosaurs** - Reptiles that arose in the Carboniferous before lineage that led to modern mammals. - Single temporal fenestrae (like modern mammals vs ancestor reptile lineage that had 2) - Relatively posterior position of the orbit; most were carnivorous, but some were herbivorous. - **Carnivorous Pelycosaurs** - Sail: May have been used in intra-specific communication or as a solar collector. - **Herbivorous Pelycosaurs** - Herbivorous forms had blunt teeth organized as a crushing plate and a lateral, expanded rib cage suggesting a large gut used in fermentation of plant material. - **Synapsids: Therapsids** - Early groups evolved in the early Permian and radiated in the late Permian, replacing pelycosaurs. - Dominant throughout the world until the end of the Triassic. - Earliest therapsids (Biarmosuchia) displayed temporal fenestrae and reduction of palatal teeth. - **Therapsids: Dinocephalians** - Large animals of the middle Permian with heavy skulls (Probably used in intra-specific head-butting). - Begin a trend toward more erect limbs. - **Therapsids: Cynodonts** - Mammal-like reptiles that arose in late Permian and radiated mostly in the Triassic - Evolved changes in jaw musculature that allowed chewing. - Adductor differentiates into masseter (m) and temporalis (t) muscles, expand and invade larger areas of the skull roof bones. - **Other Cynodont Characteristics** - Nasal turbinates for regulation of heat and water exchange. - Division of food and air passages by secondary palate. - Suggest endothermy and active lifestyle. - **Synapsids: First Mammals** - Arose in late Triassic (~210 Mya) from Cynodont ancestor. - Small insectivores displaying agile, rapid movements. - Endothermy with enlarged brain for better hearing and smell. - **Mammalian Characteristics** - Feed young milk secreted from mammary glands. - Extended parental care of young. - Large brain/body size ratio. - Hair. (Cintegumentary derivative). - **Fossil Mammals: Skeletal Characteristics** - **Regional differentiation of vertebrae:** - **Cervical:** Lack or reduction of ribs, seven cervical vertebrae. 1) two condyles, 2) best atlas-axis rotation. - **Thoracic:** ribs - **Lumbar:** no ribs - **Sacral:** articulate with pelvic girdle - **Caudal:** Presence of hemal arch - **Fossil Mammals: Middle ear bones** - Evolved from 1st and 2nd branchial arches: 1. Palatoquadrate → quadrate → incus 2. Mechel's cartilage → articular → malleus 3. Hyomandibula → columella → stapes - **Fossil Mammals: Jaw evolution** - Lower jaw is now made up of a single bone, the dentary. - Jaw joint is now between dentary and squamosal. - Quadrate and articular are now part of the middle ear. - **Fossil Mammals: Dentition Evolution** - Mammals have teeth with specialized functions (Incisors, Canines, Premolars, molars) # Lesson 15 - **Mammals arose ~210 Mya; dinosaurs arose ~230 Mya** - **Traditional ideas** - Early mammals were small shrew-like animals. - They persisted amongst the dominant dinosaurs without diversification into new lineages and niches. - Evolved into many diverse lineages after extinction of the dinosaurs when niches became available. - **Modern Ideas** - Mammals started to diverge before the kT extinction ~65 MYA and continued to diverge. - **The rise of Modern Mammals and KT extinction** - Is there an association between the loss of dinosaurs and the diversification of mammals? - Yes! Increased diversification of living mammals after loss of dinosaurs. - Did the first true mammals persist as small insectivores without diversification into other lineages amongst the dominant dinosaurs? - No! Most diversification events before the KT extinction but often unsuccessful. - **Living Groups of Mammals** - Monotremes - Metatheria (Marsupials) - Eutheria (Placentals) - **Modern Mammal Integument: Specialized Glands** - **Sebaceous Glands:** - Alveolar glands. - Oily/waxy secretion often with hair. - Waterproof hair and protect skin from drying. - **Sweat Glands** - Tubular glands - Secrete water, salts, urea - Some important for thermoregulation - **Mammary Glands** - Develop from clumps of cells in the ectoderm during embryonic development - Number and location of nipples varies across species. - Provide nutrition for young offspring. - **Scent Glands:** - Some derived from sebaceous glands, others from sweat glands. - Defense, Sexual Selection. - **Modern Mammal Integument: Derivatives** - **Epidermal derivatives:** - Claws, hooves and nails at the end of digits. - Horns (most not shed; keratin over bony core) - Antlers (shed; mostly bone) - Hair (thermoregulation and sensory organs) - **Dermal derivatives:** - Osteoderms (only armadillos; exceptionally thick dermis) - **Modern Mammals: Monotremes** - Likely arose in the lower Jurassic and evolved independently ever since (e.g., no teeth in adults). - Share with mammals' hair, endothermy and suckling of young. - Lack nipples, external ears, and embryos develop in leathery eggs (primitive amniote character). - Modern representatives include the platypus and echidnas. - **Modern Mammals: Marsupials (Metatheria)** - Found predominantly in Oceania (~200 species). - ~100 species in the Americas, only one in North America (Virginia opossum). - Give birth to tiny young who suckle until they grow much larger, often in a specialized pouch of the mother. - **Modern Mammals: Placentals (Eutheria)** - Most diverse and widespread group of mammals. - Radiated extensively after the kT extinction but limited diversification during the last 50 My. - Prolonged gestation of embryo in uterus with placenta. - Distributions correlate with isolation of continents as they drifted away from the earlier supercontinent (Pangea). - **Importance of Continental Drift** - Marsupials likely arose in what would become North America. - Placentals likely arose in Asia. - Note: No living marsupials in Eurasia and Africa. - **Marsupial Diversity** - **South American (gray)** (Opossums and Shrew Opossums) - **Australian (black)** (Tasmanian devil, bandicoots, bilbies, wallabies, kangaroos, wombats, Koalas) groups are distinct as they became isolated after continental breakup. - Australian groups occupy the same niches as placentals elsewhere (convergence evolution). - **Eutheria (Placental) Diversity** - **Afrotheria:** - Evolved in Africa after breakup from other land masses (~105 Mya). - Species filled a diversity of ecological niches over ~70 My in relative isolation. - Africa collided with Europe/Asia ~30 MYA, so some species became located on those continents. - **Xenarthra:** - Diversified in South America after breakup. - Extant species are the armadillos, sloths and anteaters, but the group has a rich history. - Extinct forms include giant armadillo-like animals and giant ground sloths.. - **Boreoeutheria (Laurasiatheria + Euarchontoglires):** saw an explosive radiation of mammals in the Paleocene after the extinction of dinosaurs - Living orders are insectivores, true carnivores, dermopterans, bats, primates, perissodactyls and rodents arose during the Paleocene radiation, whereas other modern orders arose in the subsequent Eocene Period (56-34 MYA). - **Extensive Adaptive Radiations of Mammals?** - Is it... - Extended parental care - Greater intelligence - Versatile feeding mechanisms (dentition) - Locomotory adaptations - One or a combination of key adaptations promoted radiation into new terrestrial (and some marine) niches more quickly than reptiles, birds or amphibians. # Lesson 16 - **Respiration in Fishes (Re-Cap)** - Dual pump ventilation - Tidal ventilation - **External Gills in Amphibians** - **Pond type** (Ambystoma tigrinum) - **Stream type** (Gyrinophilus porphyriticus) - **Mountain brook type** (Rhyacotriton olympicus) - Amphibian larvae and some adult salamanders (Paedomorphosis) have external gills only briefly after hatching. - Typical anuran larvae have external gills that are internalized as part of their buccal pump mechanism used for filter feeding. - External gills reliant on flow of water in the environment or waving of the gills in stagnant water. - **Cutaneous Respiration in Amphibians (important)** - **How does it work?** - Low keratinization of the skin is required for efficient gas exchange. - Low keratinization = water loss in air. - Water or moisture needed to maintain integument and increased surface area. - Requires blood capillaries close to surface of exchange. # Lesson 17 - **Vertebrate digestive systems are involved with:** - Receiving, storing, breaking (physically and chemically) food. - Absorbing nutrients and water from food. - Storing and discharging wastes. - **Component Overview** - **Main digestive tract includes:** - Mouth - Pharynx - 'Tubular Parts' (Alimentary canal) - Esophagus - Stomach - Intestines (small + large) - **Accessory organs include:** - Tongue, teeth, salivary glands, pancreas, liver. # Attachment Types of Teeth - **Acrodont dentition:** teeth attached to the outer surface or to the summit of the jawbone (many teleosts). - **Pleurodont dentition:** Attached to the inner side of the jawbone (Iguanas, Salamanders, many lizards). - **Thecodont dentition:** teeth occupy bone sockets or alveoli (some fishes, crocodilians, fossil birds, mammals). - **Tooth Variation** - **Homodont:** teeth all the same size and shape. - **Heterodont:** teeth vary morphologically. - **Mammalian Teeth:** - **Heterodont dentition:** with species-specific number of teeth. - Evolved along with the ability to chew. - **Oral (Salivary) Glands:** - **Multicellular glands with ducts:** - Only found in tetrapods and not fishes. - **Primary Function:** moisten food for lubrication. - **Specialized functions:** - Allows tongue to be sticky to assist prey capture (frogs and anteaters). - Allows start of starch digestion (some mammals). - Modified into venom glands (some snakes/lizards). - Salt excretion near orbit (marine reptiles and birds). - **Esophagus** - Muscular tube between pharynx and stomach. - Greatly folded and distensible lining, rich in mucous glands. - Conducts food to stomach. - Modified into the crop in some birds (storage of grain). - Short in fish and hard to distinguish from stomach. - Involved in closing the pathway to the stomach during respiration when water is pushed through the gills. - **Stomach** - Muscular chamber that begins at the end of the esophagus and terminates at pylorus (opening surrounded by the pyloric sphincter). - Contains gastric glands that produce hydrochloric acid. - May have evolved as a storage sac. - Digestive function involves chemically breaking down food (little absorption). - **Stomach - Birds + Crocodiles** - Modified into 2 parts: - **Glandular Proventriculus:** secretes digestive enzymes. - **Muscular gizzard:** tough horny layer for grinding and mixing food with gastric secretions; sometimes contains little stones swallowed by bird. - **The stomach of a calf (ruminant)** - Rumen - Omasum - Reticulum - Abomasum # **Aspiration Pump of Amniotes** - **Buccal cavity changes little** - **Ribs and intercostal muscles:** Power the pump in most reptiles. - **Diaphragm muscles and rib cage:** Participate in lung ventilation in mammals. - **Air is sucked into lungs because of negative pressure (tidal air flow).** # **Bird Lungs** - **Aspiration pump** (like other amniotes) but lungs are coupled with air sacs- unidirectional air flow. - **Air flow in the lung** is dorsobronchus → parabronchus → ventrobronchus, but the complex network of air sacs involved. - **Gas exchange occurs in small capillaries in the walls of the parabronchi.** # **Bird Lung Ventilation** - **Two cycle breathing:** - Inhaled air is divided into lung and posterior air sacs; the latter perfuses lungs during first exhalation. - Second inhalation similar, but pushes air in the lungs into anterior air sacs, which is vented out during second exhalation. # **Respiratory System across Vertebrates** - **Is air or water flow unidirectional or bidirectional across the respiratory surface in these animals?** - **Which is most efficient?** - **Gas Transfer at Respiratory Surfaces** - **Mammals:** Blood encounters relatively constant gas concentrations (uniform). - **Birds:** Blood encounters increasing gas concentrations allowing progressive loading of oxygen in a cross-current exchange system. - **Fish:** Blood first encounters lower gas concentrations and is fully equilibrated with oxygenated water in a Counter-Current System. - **Evolution of Lung Ventilation** - Alveolar lung = many levels of branching. - Faveolar lung = 2-3 levels of branching. - Faveolar ≠ unidirectional (See Squamates). # **Circulation in Fishes** - **Most fishes:** - **Single-circuit circulatory system** - 2 'true' heart chambers (Atrium and ventricle) - 'accessory' chambers (Sinus venosus or bulbus arteriosus) # **Variations on Double-Circuit Pump Pattern (Reptiles)** - **3 Chambered heart:** (two atria, one partially divided ventricle). - **Ventricle partially divided into 3:** (Cavum pulmonale, Cavum arteriosum, Cavum venosum). - **Deoxygenated blood from the body (systemic) enters the heart at the right atrium.** - **Oxygenated blood from the lungs (pulmonary) enters the heart at the left atrium.** - **Ventricular cava allows transfer of deoxygenated blood to the lungs when breathing air and a lung bypass when diving, saving energy.** # **Variations on Double-Circuit Pump Pattern (Birds/Mammals)** - **4-Chambered heart:** (two atria, two ventricles). - **Complete separation of pulmonary and systemic circulation (no mixing).** - **Deoxygenated blood from the body (systemic) enters the heart at the right atrium.** - **Oxygenated blood from the lungs (pulmonary) enters the heart at the left atrium.** - **Absence of cardiac shunt:** probably an adaptation to allow different arterial pressure in lungs vs body in active animals. # **Fetal Circulation in Mammals** - **Uptake of oxygen and nutrients occurs at the placenta.** - **Need to shunt most of blood away from developing lungs and into systemic circulation.** - **Bypass 1:** Blood enters right atrium and exits through foramen ovale to left atrium and left ventricle, then to head and upper body. - **Bypass 2:** Remaining blood enters right ventricle and exits pulmonary artery; travels through ductus arteriosus to lower body and placenta to be oxygenated. # **Lesson 18** - **Vertebrate digestive systems are involved with:** - Receiving, storing, breaking (physically and chemically) food. - Absorbing nutrients and water from food. - Storing and discharging wastes. - **Component Overview** - **Main digestive tract includes:** - Mouth - Pharynx - 'Tubular Parts' (Alimentary canal) - Esophagus - Stomach - Intestines (small + large) - **Accessory organs include:** - Tongue, teeth, salivary glands, pancreas, liver. - **Esophagus:** - Muscular tube between pharynx and stomach. - Greatly folded and distensible lining; rich in mucous glands. - Conducts food to stomach. - Modified into the crop in some birds (storage of grain). - Short in fish and hard to distinguish from stomach. - Involved in closing the pathway to the stomach during respiration when water is pushed through the gills. - **Stomach:** - Muscular chamber that begins at the end of the esophagus and terminates at pylorus (opening surrounded by the pyloric sphincter). - Contains gastric glands that produce hydrochloric acid. - May have evolved as a storage sac. - Digestive function involves chemically breaking down food (little absorption). - **Stomach - Birds + Crocodiles** - Modified into 2 parts: - **Glandular Proventriculus:** secretes digestive enzymes. - **Muscular Gizzard:** tough, horny layer for grinding and mixing food with gastric secretions; sometimes contains little stones swallowed by bird. - **The stomach of a calf (ruminant):** - Rumen - Omasum - Reticulum - Abomasum