WFSC 302Exam # 4 Study Guide Lectures: 18 - Lecture 18 Know Amniote Characteristics. What is the synapsid temporal fenestration? Who does the synapsid clade include? Who are nonmammalian synapsids? When did the synapsids begin to radiate? Where the pelycosaurs monophyletic? When did the therapsids appear and how did they interact with the pelycosaurs? What are the two major purposes for the trends we see in non-mammalian synapsids? Amniote Characteristics: Amniotes:Tetrapods belonging to Amniota.Include turtles, lepidosaurs, mammals, reptiles, and birds.Monophyletic groupCannot lay eggs in water. Have dispensed with a free living larval stage.Anamniotes: Non-amniote vertebratesInclude majority of fishes and all amphibians.Paraphyletic groupAmniote Characteristics- Amniotic egg: egg with extraembryonic membranes surrounded by a shell.o Amniono Choriono AllantoisTemporal Fenestration:- Diapsid condition: two fenestrae behind orbit- Anapsid condition: No temporal fenestra - Synapsid condition: one fenestra behind orbitSynapsid clade:1) Nonmammalian synapsids, or “Mammal-like reptiles” (extinct)2) MammalsNonmammalian synapsids:- Pelycosaurs- non-monophyletic- Therapsids -o Non-cynodonto Cynadont1st synapsids appear in the Paleozoic, 300 mya, the late Carboniferous period. They were the first amniotes to radiate in terrestrial habitats.Therapsids appeared in the mid-late Permian, they were very diverse, and probably outcompeted the Pelycosaurs.Two Major Purposes:1. Trend toward increased metabolism endothermy.2. Trends toward a more mammalian form.Lecture 19 When did the majority of mammal evolution occur? What are the two major geographic eras? What amniotes masticate food? What are some of the earliest features of mammals? Explain the evidence of lactation. What is the order? Why was lactation believed to have started?2/3 of mammalian evolution occurred in the Mesozoic Era, 250-65 mya.Two major geographic eras:Northern super continent – LaurasiaSouthern super continent-GondwanaMammals are the only amniotes to masticate food.Features of earliest mammals:- Dentary- squamous jaws, articulation between two bones- Hair- Evidence of lactationo Diphyodonty o Precise occlusion- only 2 sets of teeth, one on the upper jaw and one on the lower jaw.o Lactation- tooth eruption would be delayed, allowing a prime time for young to feed on a liquid diet for food. Lactation---diphyodonty---precise occlusionLactation is believed to have started mainly for nutritional and selective pressures for immunity in young.Lecture 20Know what the two subclasses of Mammalia are. What are characteristics of Monotremata? List marsupial features. What are characteristics of Eutherians? Two subclasses: Prototheria & TheriaMonotremata:- Lay eggs- Mammary hairs for lactation (no nipples)- Small cochlea- No pinna- Cloaca- Lack teeth as adults- Male platypus have venomous spurs on the hind legs.Marsupial:- Young born underdeveloped and continue development in the pouch- Different tooth formula- Usually lack auditory bulba- Epipubic bones- used to keep the hind limbs in place and belly from swaying.Eutherians- Auditory bulba- Marsupials replace only the last premolar- Postorbital bar- seen more in arborial mammals active in day.Lecture 21 What are the reproductive similarities between Eutherians, Marsupials, and Monotremes? Explain Therian reproduction. What are the differences morphologically between Therians and Marsupials? What are some of the reproductive specializations?Reproductive similarities (Monotremes, Marsupials, & Eutherians): - Lactation- Blastocyst- forms after the sperm fertilizes the egg- Endometrium- major part of what forms from the placenta later- Corpus luteum- follicular cells leftover produces hormones necessary to start pregnancy.- All eggs are fertilized in fallopian tubes.- Live birth vivparityTherians:- Short gestation, still have placenta- Embryonic diapause- Body can determin when to have young, so the fertilized egg can sit until adequate environmental conditions arise for providing for fetus development.- Testes descend into scrotum during reproductionMorphological differences between Marsupials and therians:- Marsupials- Two lateral vaginae- Forked penis- Midial canal pseudovaginal canal forms during gestation- Milk contains high fat and protein for younger young, and higher sugar for older- can have two different types of milk for different aged young.Extreme reproductive specializations:o Eusocialityo Spotted hyenas- look masculineLecture 22 What is the digestion in herbivores like? Locomotion? What about Aquatic mammals? What roledoes sociality play? What are some characteristics of sociality in mammals?Digestive System:- Two types:o Rumination/foreguto hindgutLocomotion:- Adaptions:o Fossorial: Majority of life is underground Small stocky body shape Short powerful limbs for digging Lips close behind incisors- Cursorialo Running- limbs are elongated in distal portion of legs Longer legso Lost clavicle Carnivores have floating clavicle Artiodactyls have lost their clavicleAquatic Life- Spend majority of life in the watero Pinnipeds-come out to give birth (sea lions, walruses)- Axial swimming (dorsal undulation)- Cetacean:o Hind limbs lost If have remnants they are tiny body fragments, useless Use tail and fins for locomotion, cartilaginouso forelimbs: shortSociality:Being social- living in structured group, some form of sociality in every vertebrate group. Majority mammal species are asocial.Particularly social mammals:- large brains- longer associations between parents and young- high metabolic rates and endothermy.Sociality is also helped determined by resources, predators, helping determine social