lab practical 2

aves skin

frog skin

fish skin

snake skin

mudpuppy temporal fenestration & adaptations

• does not have true fenestrae

• retains paedomorphic traits

frog temporal fenestration & adaptations

• does not have true fenestrae

• open (gymnokratophic) cheek regions

loggerhead turtle temporal fenestration & adaptations

• anapsid

• massive, wide jaws

• diet-driven shape shift (ontogeny)

• keratin beak

tuatara temporal fenestration & adaptations

• diapsid

• acrodont dentition

python temporal fenestration & adaptations

• diapsid

• loose lower jaws

• swinging quadrate & supratemporal bones

alligator temporal fenestration & adaptations

• diapsid

• secondary hard palate

wolf temporal fenestration & adaptations

• synapsid

• sagittal crest

human temporal fenestration & adaptations

• synapsid

• expansion of braincase

• facial reduction

• foramen magnum shift

• reduction of brow ridges

• chin development

key features of tuatara skull

• diapsid fenestration

• acrodont dentition

• double row of teeth on the upper jaw

• parietal “third” eye

• no external ear openings

what structure do turtles have that has functionally replaced teeth?

a beak

tuatara skull

• classic/ complete diapsid

• complete lower temporal bar

• akinetic cranial kenesis

• two upper rows of teeth, one lower

• acrodont dentition

• beak-like premaxilla shape

iguana skull

• modified diapsid skull

• incomplete/ absent lower temporal bar

• kinetic cranial kenesis

• single upper row, single lower row

• pleurodont dentition

• triangular/ blunt premaxilla shape

in what ways are the python teeth adapted for predation?

• backward- curving teeth

• 6 rows of aglyphous teeth

• rapid tooth replacement

what is the purpose of the secondary palate?

separates mouth from nasal cavity & allows us to breathe with our mouths closed

in what way is the frog skeleton modified for jumping?

• elongated hindlimbs

• urostyle

• rigid, short spine

• fused forearm ones

• specialized pelvic & hip girdles

• lightweight skull

what is the function of the urostyle?

transmits & absorb the immense backward thrust from the legs directly into the rest of the body without bending sideways

evolutionary origin and function of columella

• ancestral homolog of stapes in mammals

• derived from hyomandibular bone in fish

• transmits airborne sound vibrations from the external tympanic membrane to the inner ear receptors

what family do axolotls belong to?

mole salamanders

• Ambystomatidae

paedomorphic traits of axolotls

a developmental trait where it reaches sexual maturity & adulthood while retaining its larval, juvenile body structures

• feathery external gills

• dorsal & tail fins

• aquatic lifestyle

• underdeveloped facial features

• skin respiration

specializations of snake skeletons

• kinetic skull

  • unfused bone

  • independent L & R jaws

  • pterygoid walk

  • elongated quadrate

  • specialized fangs

• hyper-vertebral skull

  • high vertebral count

  • zygosphene-zygantrum joints

• ribs & absence of sternum

  • no breastbone

  • elastic expansion

  • locomotion aid

• vestigial limbs & pelvic remnants

  • no front limbs

  • pelvic spurs

why don’t lizards run marathons?

• they cannot run & breathe at the same time

  • evolutionary hold over from when early tetrapods moved onto land

  • monitor lizards have gular pumping

how did snakes lose their legs?

• sonic hedgehog- required for limb development

  • is only on very briefly on in snakes

• 3 mutations in the sonic enhancer

differences between snakes and legless lizards

• snakes

  • very flexible

  • very short tails

  • evolved from legless lizards

  • mandible is not fused

  • boas & pythons have vestigial legs

  • forked tounges

• leglesslizards

  • moveable eyelids

  • external ears

  • long tails

  • can drop tails

how do snakes slither?

• take advantage of rough scales on their underside

  • they catch & grab the ground to push themselves forward

• combination of friction & weight distribution

how do the bellies of snakes and legless lizards differ?

• lizard

  • longer tail

  • smooth

• snake

  • short tail & long trunk

  • scaly

hypotheses for the origin of the turtle shell

• The De Novo (Broadening Ribs) Hypothesis

  • The shell did not form from external skin scales (osteoderms) fusing together. Instead, it evolved from the deep skeletal structure through the broadening and flattening of the ribs and vertebrae

• The Composite (Osteoderm / Dermal Armor) Hypothesis

  • The shell is a complex composite structure formed by the fusion of dermal armor or scales (osteoderms) in the skin with the underlying endoskeletal ribs and backbone

what are scutes made out of?

keratin

marginal scutes

the series of scutes along the outer edge/ rim of the carapace

pleural scutes

paired rows of scutes on either side of the vertebral scutes, between the vertebrals & marginals

vertebral scutes

central longitudinal row of scutes running along the midline of the carapace

what are the relative positions of scutes and shell bones to each other?

• scutes overlap with each other & are not a direct replication of the bones beneath them

• provides extra protection

how do ribs contribute to the structure of the shell?

• the ribs make up the plastron & carapace

• they are flattened & widened

• protection evolved secondarily, they are hypothesized to have developed as a stable base for digging holes

what is unique about the turtle pectoral & pelvic girdles?

positioned inside rib cage rather than outside of it

synapomorphies of Lepidosaurs & Squamates

• keratinous, overlapping scales

• transverse cloacal slit

• autotomy plates in caudal vertebrae

what kind of dinosaur was Allosaurus? what significant bone was discovered and what is its significance?

• large, bipedal therapod (meat-eating)

• carpal bone (found in the wrists of therapods, reshaping out understanding of how bird-like flight evolved)

adaptations of Velociraptor skull

• light skull

• large temporal fenestration

• ziphodont teeth

• puncture-and-pull feeding

Velociraptor fenestration

• 5 fenestrae

  • maxillary

  • antorbital

  • upper temporal

  • lower temporal

  • mandibular

how has the hypothesis explaining the purpose of the giant claw on the foot of dinosaurs changed over time?

shifted dramatically from aggressive combat theories to behavioral, biochemical & ecological models

describe the hands of Megaraptor

• 3 digits

  • 1st is short with an extremely long claw

  • 2nd is long with a medium length claw

  • 3rd is slightly longer than 1st with a short claw

describe the hands of Utahraptor

• feathered

  • 3 digits

  • middle finger longest

  • all with relatively equal digits & claws

how is Archaeopteryx an intermediate between theropods & extant birds

it has many features seen in both theropods & birds, as well as transitional characteristics

• teeth: therapod-like

• tail structure: therapod-like

• forelimbs & digits: transitional

• sternum: theropod-like

• feathers: bird-like

• skeletal fusion: bird-like

• furcula: bird-like

key characteristics & temporal fenestration of Archaeopteryx

• small, shark, non-serrated teeth

• unfused cranial bones

• closed temporal bar

• unjoined premaxillae

• tetraradiate palatine

• bird-like palatine & mandible

• enlarged brain

significance of Confuciusornis sanctus fossil

• transition from teeth to beaks

• long, bony reptilian tail → pygostyle

• clawed wings

• ornamental feathers & sexual dimorphism

• crucial model organism for understanding how early birds transitioned between gliding, powered flight & alternative aerial lifestyles

pileated woodpecker skull & feeding habits

• long & narrow

• eats fruit, nuts & insects

northern cardinal skull & feeding habits

• short & thick

• adults eat seeds, young are fed insects

ruby throated hummingbird skull & feeding habits

• long & incredibly thin

• eat flower nectar & insects

american crow skull & feeding habits

• long & thick

• eats 70% plants & 30% animal matter

red-tailed hawk skull & feeding habits

• short & thick

• small to medium sized mammals

owl skull & feeding habits

• short & thick

• small mammals, insects & fish

features of a feather

pennaceous barb structure

rigid, interlocking structural units that makes up the smooth, flat vane of a bird’s flight & contour feathers

plumulaceous barb structre

loose, soft & fluffy arrangement found at the base of contour feathers making up the entirety of down feathers (no interlocking hooklets)

feather types in wings

which bones do the primary and secondary feathers attach?

• hand/ manus

  • major metacarpal

• ulna

what order do Cooper’s Hawk & Red Tailed Hawk’s belong to?

Accipitriformes

what order do American Tree Sparrows & Blue Jays belong to?

Passeriformes

what order to Wood Duck’s belong to?

Anseriformes

what order do Great Horned Owls belong to?

Strigiformes