Lecture 4 Flashcards
List the four classes of tetrapods and recognize examples and characteristics of each class.
Amphibian: Requires aquatic environment for reproduction and supplemental gas exchange, salamander.
Reptilian: ectothermic, scales, lungs
Aves: Feathers
Mammals: Hair or Fur
Identify the group of Devonian tetrapods that is presumed to have given rise to modern amphibians.
Temnospondyli Early carboniferous period (Mississippian) Example: Eryops
List the three orders of modern amphibians and list major characteristics of each order.
Caudates (Urodeles): Name implies tail, Modern Salamanders, Early Karurus from Upper Jurassic.
Anurans: Name implies lack of tail, modern frogs, Early Vieraella had longer vertebral column and shorter hind legs.
Apodans: Name implies lack of limbs, Caecilians are worm-like, externally segmented.
Characteristics (All): Pedicellate teeth, Cylingrical vertebral centra, two auditory ossicles.
Name the two groups of anapsids and indicate which one is the stem reptile for all other reptiles and list its characteristics.
Chelonia (tutles) and Cotylosauria (Didactomorph).
Cotylosauria are the Stem Reptile and have no arch or additional openings of skull, it does have dermal armor and a laterially flatted skull. Early forms were the carboniferous captorhinids.
Describe the distinguishing feature between the two groups of dinosaurs.
Ornithischians (Bird hipped dinosaurs): Tetraradiate pelvic girdle, included quadrupeds and bipeds. Example: Triceratops.
Saurischians (Lizard-hipped dinosaurs): Triradiate pelvic girdle, included quadrupeds and bipeds. Example: Tyrannosaurus.
List the three subgroups of modern lepidosaurs and compare their skull type with regard to lateral, postorbital openings.
Sphenodon, Snakes, and Lizards.
Sphenodon: True diapsid skull with two lateral openings, primitive pelvic girdle.
Explain why dinosaurs form a paraphyletic group.
Paraphyletic groups include a common ancestor and some but not all its descendants. Dinosaurs refer to ancestors of birds and dinosaurs, but does not include modern birds.
List reptilian characteristics found in early birds such as
Archaeopteryx.
Bony tail, separate fingers with claws, and teeth.
Describe theories on the origin of flight in birds.
Birds evolved flight (feathers) for thermal insulation, insect catching net, better pursue prey or escape predation, and to better roost in trees at night.
Identify the earliest group of synapsids.
Pelycosauria: Few feet long, not contemporary with dinosaurs, dorsal sail-like structure probably for thermoregulation.
Identify characteristics shared by mammals and
advanced therapsids.
Secondary palate (premaxillary, maxillary, and palatine bones)
Pterygoid bones solidly fused to braincase.
Enlarged dentary bone
Differentiation of teeth into incisors, canines, and cheek teeth.
Considerable regional differentiation if ribs and vertebrae.
Legs pulled in
Illium extended forward
Elongated sacrum
Feet well-developed.
Jaw articulation pattern: therapsids have both reptilian (quadrate and articular bone) and mammalian (temporal bone and mandible).
Identify mammalian characteristics.
Live births, endothermy, respiratory diaphragm, four-chambered heart with completely divided ventricles, Neocortex multiple layers of neurons covering cerebral lobes of brain, Double occipital condyle, mandible consisting of a single bone (dentary), Dony secondary palate, Loss of interclavicle (except for egg layers), Hair/fur, possesses mammary glands.
Name the three groups of modern mammals and the major characteristic that separates them.
Monotremes (Prototheria): Egg Laying
Marsupials (Theria): Trituberculate Molars
Placentals (Theria): Trituberculate Molars
Identify the earliest group of mammals and describe their dentition.
Morganucodonts: Hertodonts with triconodont molars
List and describe some of the requirements for terrestrials. How does Reptilian adaptive radiation factor into terrestrialism.
New adaptive changes allow for the ability to fill many new niches.
Reptilian Adaptive Radiation refers to the explosion of precursor characteristic that were responsible for traits required of a land animal which started with Cotylosauria. The evolutionary drive for terrestrial life was seeking new aquatic environments after water dried up as well as to find more food (insects).
Terrestrialism required a solution to desiccation (drying out). To do this, terrestrials started using ADH for water retention. Terrestrials had to resist gravity which the buoyancy of water preformed for aquatic life. The solution was to more dorsally position the vertebral column, develop the pectoral and pelvic girdles (attach it to vertebral column), and move axial musculature to limbs. Terrestrials changed sensory organs by not using Lateral Line System of EM wave detection in water, evolved hearing for air by changing Lagena to cochlea, and evolving the cornea for coarse adjustment and lenses for fine adjustment. Terrestrials also changed the excretion of nitrogenous waste and reproductive function.
