Vertebrate Zoology Test 3

What types of changes were required in the body plan to transition to land?

• musculoskeletal changes

• vertebral elements

• circulation and respiration changes

• kidney function with loss of gills

haversian systems

concentric layers around blood vessels forming cylindrical units. facilitate transport of nutrients through blood vessels and support bone health

What type of bone is external layers? What type of bone is internal layers?

external - lamellar

internal - cancellous

Describe vertebrate joints

• joints are covered by smooth layer of cartilage to reduce friction as joints move

• the bone within the joints is cancellous

• joint is enclosed in joint capsule that contains synovial fluid for lubrication

How was axial skeleton modified for support on land?

• bony connection between head and pectoral girdle is lost

  • now flexible neck

• atlas and axis highly differentiated in mammals

• zygapophyses - processes on vertebrate that resist twisting and bending so spine can support weight on land

• musculature assumes two new roles

  • postural support of body

  • ventilation of the lungs

True or False: epaxial muscles in fish are undifferentiated but derived tetrapods have differentiated epaxial muscles

true

What are hypaxial muscles essential for in land vertebrates?

• essential for respiration on land in early vertebrates because pressure of water column no longer aiding to force air out from the lungs

• three layers: external obliques, internal obliques, and transversus abdominis

what is the primary propulsive mechanism of the appendicular skeleton?

hind limbs

the pelvic girdle fused to modified sacral vertebrae to what three paired bones?

ilium, pubis, ischium

trapezius

large muscle that runs from top of neck and shoulders to pectoral girdle

double circulation

pulmonary circuit supplies lungs with deoxygenated blood and systemic circuit supplies oxygenated blood to the body

respiration in tetrapods

• early tetrapods similar to lungfish but internal gills are lsot

• aortic arch two lost because its missing in all living tetrapods

• some cutaenous circulation

• amniotes lack any cutaneous circuit

non-amniotic tetrapods

• not amphibians but had amphibious lifestyles

• much larger than amphibians

Stem tetrapods

• include acanthostega and ichthyostega

• two main groups of paleozoic tetrapods

• stem amphibians were temnospondyls

stem amniotes

reptiliomorphs

more amniote like than amphibian like

Amniotes vs Nonamniotes

Amniotes

• two major liniages Sauropsids (reptiles and birds) and synapsids (mammals)

• embryos surrounded by membrane sourced from embryo itself

• static pressure feeding

non-amniotes

• mostly aquatic, fish and amphibian

• embroys enclosed and protected by membranes produced by reproductive tract of female

• descendants of subclass lissamphibia

• inertial feeding

Evolutionary history of amphibian lineage

• evolved in Devonian

• diversified and became dominant during carboniferous and Permian periods

• reduction in body size and diversity decreased

what eras are present in the Phanerozoic eon

Paleozoic, Mesozoic, Cenozoic

What are the three modern orders of amphibians?

• anura - frogs and toads

• caudata (urodela) - salamanders

• Gymnophiona (apoda) - caecilians

Amniotic development

• embryo has fluid-filled layers surrounding embryo

• amnion filled with amniotic fluid surrounds embryo with stable fluid environment

• allantois - membranous sac in embryos that helps form umbilical cord and placenta

  • permits gas diffusion for embryos

  • removal of waste products

• yolk sac provides food for embryo as it develops and reduced in size as embryo matures

• chorion - outer surrounding membrane that makes up chorionic cavity in some species. protects embryo to provide stable internal environment

• albumen - exists around chorion in form of white of the egg

• hard shell to prevent dying on outside and allows for laying eggs on land

Placenta as modified egg

• embryos still surrounded by amnion filled with amniotic fluid

• allantois and yolk sac become umbilical cord

• physically attaches embryo to uterine wall of mother

how are amniotes typically classified by temporal fenestration (number of holes in head)?

• anapsid - without junction (early amniotes and turtules)

• sinapsid - joined, single arch

• diapsid - two arches

Why is air easier to breath than water?

• negative-pressure aspiration pump - expansion of rib cage by intercostal hypaxial muscles create negative pressure in abdominal cavity and sucks air into lungs

• air is expelled by compression of abdominal cavity and contraction of transervus abdominis muscle

Posture and balance on land

• communicate singles from periphery to brain

• proprioceptors involved in transporting information from limbs

• muscle spindles detect amount of stretch in muscle and tendon organs convey information about position of joints

ectothermal vs endothermal

• ectothermal - rely on environmental heat sources to regulate body temperature

• endothermal - generate heat through body processes to maintain constant body temeprature

True or False: Nonavian dinosaurs and all living reptiles and birds are diapsids

true

What are the two main groups of Diapsids

• archosauromorpha - extinct pterosaurs and dinosaurs, crocodilians, and birds

• lepidosauromorpha - tuatara and squamates (lizards and snakes), three groups of specialized marine tetrapods

Describe the different lepidosauromorpha groups

• placodonts

• Plesiosaurs

• Ichthyosaurs

• Mosasaurs