lec 11: display, defense, and thermoregulation

what is the likely fxn of the plates of stegosauria? the thagomizer’s function?

thagomizer fxn: defense

plates:

• not likely defense or thermoregulation

• social display

  • sexually dimorphic

  • blood pumped into plates could alter color

compare and contrast ankylosauridae and nodosauridae defense

ankylosauridae:

• armor

• spikes and horns

• tail club instead of large shoulder spikes

• camouflage

nodosauridae:

• armor

• large shoulder spikes instead of tail club

• camouflage

what evidence suggests that pacchycephalosauria and ceratopsia dueled with rivals

intraspecific aggression

• pachycephalosauria

  • high-dome heads have highest injury (consistent with adults vying for mates)

  • little to no injury in flat-headed and low-dome heads (consistent iwht juveniles and adults choosing the mate)

  • pattern is consistent across diff species

• ceratopsia

  • preseved injuries are consistent with using the horns for combat

  • triceratops have more injuries on frills than centrosaurus

high-dome head injuries (adults)

• concentrated in frontal skull region

• head-butting behavior similar to bison

low-dome heads (subadults)

• more evenly distributed around top of skull

• head-butting and necking behavior similar to goats and giraffes

compare the visual display of hadrosaurinae with audiovisual display of lambeosaurinae

hadrosaurinae

• solid crests: visual display

• crestless species have a soft-tissue crest

lambeosaurine

• hollow → audiovisual display

which dinos have a sail and what are its 2 most likely fxn

spinosaurus,

amargasaurus (diplodocoidea)

deinocheirus(maniraptor)

(not dinos: pelycosaurs, crurotarsi)

fxns:

1. thermoregulation

2. display

which dinos have fossil evidence of camouflage

ankylosauridae and nodosauridae

borealopelta markmitchelli (ankylosaur)

ceratopsia

maniraptor

• microraptor

• sinosauropteryx

what are the pros and cons of endothermy

pros:

• generate heat internally

• commonly aided by insulation

cons:

• requires more food to metabolize

how is size related to body heat? what is gigantothermy?

gigantothermy

• larger animals retain more heat

• advantage for ectotherms

• easier retain heat as ectotherms get larger

whatare the signs of endothermy

warm internal body temperature - clumped isotope analysis: attraction of 18O and 13C isotopes to each other in bones, teeth, and eggshells depends on internal body temp (more they clump 2gether, higher temp when the teeth and bone were formed or when the egg was incubated)

fast growth rate:

• high metabolism

• indicated fibrolamellar bone

• present in dino since the triassic period

large brain

• requires high metabolism

• complex social behavior like mating display

• integration of multiple of senses

parental care of young - young unable to eat enough by themselves

small body size + high activity: small size loses heat easily

thermoregulation: body aprt adaptations for retaining body heat

which dinos have fossil evidence of parental care

ceratopsian

• nests with 1-yr old young and juveniles

ornithopods

• hadrisaurodae

  • maiasaura: altricial

maniraptora

• oviraptor incubating clutch eggs

• birds

what are the benefits of being large

niche partitioning: eat food no one else can reach

defense against predation: too big to eat

protection from drought: water and fat storage

gigantothermy: large body size retains more heat because of reduced surface area