Final Cards Flashcards
what is a theropod?
= all saurschians that aren’t sauropods
- mostly bipedal
- claws
- serrated teeth
describe theropod walking
Harrow legs with one foot nearly in front the other
Horizontal, with head and tail balanced over pelvis
Tail never touched the ground: no tail trackmarks
femurs in theropods
some evolved short femurs compared to the tibia to increase speed (ornithomimids)
describe theropod grasping claws
semi-opposable thumbs that could grasp prey - in dromaeosaurs and troodontids, second digit held erect, until attacking (3 toes, 4th up and sticking backwards)
describe theropod arms
three fingered hands are most common
- four digits in more primitive theropods, and some derived forms only had 2
myths about theropod arms (3)
1) they are small
- only small related to body
2) they are weak
- might have been able to lift heavy and had huge claws
3) they were useless
- options such as mating, grasping prey
theropod jaws
carnivorous theropods had larger heads, with powerful bites compared to herbivores (theropods or not)
carnivore vs herbivore jaws
carnivores had slicing, scissor like jaw that was designed to cut through prey, not chew vegetation. Herbivorous ornithischians had grinding jaw for chewing
theropod teeth
- curved backward to hold prey
- serrated for greater cutting ability
- more rounded = less for slicing and more for crunching
not all had huge teeth:
- ornithomimids had beaks for grinding small vegetation
- short jaws for crushing (shellfish)
theropod vision
- theropods had generally excellent vision
- eyes facing forward and overlapping = stereoscopic (3D similar to us but worse)
- also has shortened snouts, to help increase range
theropod brains
had the largest brains compared to body size in dinos
sexual dimorphism
the difference in appearance (colour, size, shape, structure) between males and females of the same species
- some evidence of ornamentation, but could’ve also been colourful
- some medium and smaller theropods were multi coloured with feathers
feathers
many dinosaurs had some sort of feathers. the point when these evolved is continuously being pushed further back. most of the adaptations needed for flight happened for other reasons first.
some of these feathers are not flight feathers, but for display, insulation, and other reasons
types of feathers
1) hollow, hair like filaments (mono filamentous feathers)
2) loose, unconnected barbs (downy feathers)
3) hooked barbs on vane (contour feathers)
4) asymmetrical vane with hooked barbs (flight feathers)
uses for feathers
1) insulation
2) display
3) flight
limb to wing transition
in the fossil record, we can see changes in the size, number, and fusion in the digits of theropods
three main hypotheses for the origin of flight
1) tree down
- climbing and gliding
- claws used for climbing
2) ground up
- running and leaping
3) the compromise
- started by helping them run
what kind of hip structure is this?
saurischian
what kind of hip structure is this?
ornithischian
theropod diversity
- first dinosaurs may have been saurischians with the basic theropod appearance
- there was rapid diversification during late triassic
- sauropods split from theropods a bit later (still in late triassic)
the earliest theropod genus
herrasaurus
herrerasaurus description
walked on all four hind toes, but more advances theropods (neotherapoda) walked on only the middle three with digit 1 greatly reduced
- boxy shull and bad 3D vision
neotheropods
- one of the next clades after theropoda
- loss of fifth digit on feet and development of furcula (wishbone; two collar bones fused together)
only in birds today
coelophysis
- taxon of neotherapoda
- late triassic - early jurassic
- smallish, fast and agile, pack-hunting carnivore
- four digits on hand, but one was embedded in the hand
tetanurae
- clade after neotheropoda
- diverse group marked by stiffened tails, compared to coelophysis
- also loss of 4th digit in hand
tetanurae tails
one idea is that stiff tails helped balance bigger heads
spinosaurus
- 15 m long tetanurae theropod, with a stiff tail
- all of this points towards spending a lot of time in water
-> lived near shores, hunted fish - long snout with nostrils in middle, not front
- long, powerful arms
- dense (non-hollow) bones
- relatively weak pelvis
- flat toes
avetheropoda
- clade after tetanurae
- this group developed pneumatic (hollow) bones
- presumable, these were used to counter the increasing size in theropods, but also present in small avetheropoda too
- formed independently in other dinos
carnosauria
- taxon of avetheropoda
allosaurus
- was one of the most abundant large theropod carnivores in the jurassic
- tooth marks in stegosaurus plates and puncture wounds in allosauruses indicate they frequently fought
coelurosaurs general definition
remarkably diverse: everything from tyrannosaurs to hummingbirds
tyrannosauroidae
largest terrestrial carnivores in earths history
- at least 20 types including both big and small dinos
bite force of t-rex
= 12 800 ibs
- roughly its own weight
- 3-5 times greater than any other terrestrial carnivore
- other aquatic species have been even greater
- high bite force therefore thicker teeth
coelurosaur feet
had a middle metatarsal that tapered proximally, so that the two outer metatarsals made up most of the proximal surface
- this increased strength and agility in coelurosaurs
carnosaur feet
had 3 robust metatarsals making up much of the mid foot
ornithomimids
- very bird like (ostrich)
- long legs
- small skull, large eyes
- no teeth – plants and small animals for food
- fast runner
- evolved for speed
- mostly not carnivores
deinocheirus
- “marvelous terrible hands”
- only fossilized arms were found originally
- very long claws
- thought to look like a tyrannosaur
- no teeth
- long and skinny skull (weak)
- semi aquatic piscivore/herbivore
- gastroliths in stomach
examples of maniraptors
oviraptor
maniraptors
- clade after coelurosauria
- characterized by a modified wrist bone that allowed more movement
paraves
- clade after maniraptora
- loger arms and hands
- ‘wings’ with layered feathers
- backwards pelvis (more ornithischian - pubic bone still separated from ischium, but tilts backwards as in birds)
examples of paraves
troodontids and dromaeosaurs
dromaeosaurids
- highly predaceous and intelligent cretaceous meat eaters with serrated teeth
- fully functional front limbs (unlike many theropods)
- probably social
- called raptors informally
posture of dromaeosaur
- horizontal balanced posture
- claw lifted for running and dropped for attacking
- high degree of activity and some developed flight feathers
troodontids
- possibly entirely covered in feathers
- specimens found with melanosomes (colourful)
avialae
- clade after paraves
- characteristic: fairly long list of what makes a modern bird: full flight and loss of teeth (beak)
- feathers, stiff tail, bipedal, semi-lunate carpal, furcula, mesotarsal ankle, rear-facing pubis, hollow bones (not originally evolved for flying, but then used for flying
archaeopteryx
- taxon of avialae
- birds now known to be theropods
- jurassic bird
- found preserved in fine-grained limestone
bird characteristics vs reptile
bird:
- feathers
- fused, broad wings
- furcula
- pneumatic bones
reptile:
- small teeth
- boney tail
- 3 fingers with claws (2nd claw extended)
melanosomes
= organelles in animal cells that store melanin (a type of pigment)
- different shapes for different colours
- found in feathers of well preserved fossils
- red, black, grey, orange, brown, etc
are feathers characteristics of all dinosaurs?
- we know some saurischians did/still do have feathers
- we know sauropods didnt have feathers
- psittacosaurus thought to not have feathers (basal ornithischian) but found to have melanosomes and feather impressions
sauropodomorpha
- saurischian pelvis, bt were more derived away from their bipedal ancestry: quadrupedal, herbivores, small heads, long tail/neck
- the earliest came from late triassic
- prosauropods (early sauropods) traced from earlier bipedal saurischian ancestors
- became more like true sauropods into the jurassic
- extinct in early jurassic, but were first large herbivores on earth
prosauropods
- mostly bipedal with half moon lunate thumb claw
- ex. plateosaurus
- increasingly evolved the following characteristics as they became more like sauropods: leaf-shaped teeth, new digestive system, longer arms, longer necks/tails, increase in overall size
arms of prosauropods
- longer arms than theropods
- derived prosauropods were quadrupedal, like sauropods
- longer arms = slower
prosauropod eating
- evolved leaf-shape teeth
-> good for stripping vegetation
-> not good for chewing vegetation - developed similar structures as other herbivores to digest vegetation
-> large torso for stomach fermentation
-> gastroliths
sauropod diversity
- became very large and diverse during the jurassic and continued into the cretaceous
- group included the largest dinosaurs known
sauropod defining characters
- > 40 characters, mostly related to their familiar shape and behaviour
- quadrupeds
- herbivored - small heads
- long tails/necks
sauropod teeth
- developed skinny, pencil like teeth
- in some derived versions, the teeth were spaced only at the front
sauropod skulls
- small with large holes
- nostrils moved upwards in more derived forms
- reduced skull size relative to body size
- skull is less than 5% of body length
sauropod necks
neck vertebrae had many pneumatic holes and air pockets to counter their size
- neck vertebrae had many pneumatic holes and air pockets to counter their size
- most helt their neck horizontally, balanced by the tail
- neck and tail held upright by strong, interlocking vertebrae
sauropod necks and blood pressure
- horizontal configurations are supported by studies on the blood pressure and heart size needed to pump blood to a raised head
- would need 1/2 ton heart, 2x the blood pressure of any other animal
- but there were partly vertical dinos known (brachiosaurus)
sauropods with short necks
brachytrachelopan was a small, late jurassic member of the diplodocoid group
sauropod legs
- leg bones had much higher density than the neck bones to support the large weight
- front foot = stood up on toes (digitigrade) with one large claw
- back foot = flat toes
sauropod walking
- narrow stance with no tail marks
sauropods as prey
- sauropods were up to 300%bigger than any predator
- long whip like tails and claws
- when in herds, they would’ve been very hard to kill
sauropod rebroduction
- large sauropod egg colonies discovered
- colonies composed of cluster of 15-30 eggs with entire colony having 10,000 of eggs
- sauropods reproductive strategy was to have many eggs, only a few of which would reach mature ages
- these colonies were layered, meaning sauropods maybe returned to the same spot to reproduce
sauropod classification
2 main branched:
- diplidocoids
- macronaria
diplidocoids
- longest dinosaur but may have been 1/2 the weight of some titanosaurs
- long skulls with teeth moved to the front
- ex diplodocus, apatosaurus/brontosaurus
macronarians
- shorter, but heavier
- smaller skull with a more powerful bite
- ex brachiosaurus, titanosaurs
what is the shared derived characters of ornithischian
1)in all ornithischians the pubis is rotated backward, close and parallel to the ischium
- may have evolved to allow a more barrel-shaped (bigger) hut for digesting fibrous gymnosperms
2) all ornithischians had a predentary, a scoop-like element at the front of the lower jaw. many had full beaks ti help dig up/snip vegetation
tools for chewing vegetation
1) cropping teeth
2) diastema = gap between teeth for moving the food
3) dental battery = blocks of close-fitted molars for grinding food
4) cheeks for storing food as its chewed
5) coronoid process = area where strong muscles attach to the jaw
teeth of ornithischians
leaf-shaped teeth that were well-adapted for grinding up vegetation
basal ornithischians
- the earliest known ornithischians were bipedal, but evolved the chewing skull and longer forearms: otherwise they looked a lot like theropods
tianyulong
basal ornithischian with mono filamentous feathers
scute
a separate armor plate, typically of bone, formed in the dermis (skin). often scutes are covered by leathery skin
early thyreophorans
mix of bipedal and quadrupedal forms with rows of simple dermal armour (scutes) along the neck, back, and tail
stegosaurs
- middle to late jurassic
- scutes were highly specialized and enlarged as two rows along the back and as armour around the neck
- hind limbs longer than fore-limbs: sloped to the front for better defence but harder to run
stegosaurs eating
- leaf-shaped small teeth, but not in close rows, small cheeks and small coronoid process = chewed but not efficiently
- probably ate low-lying gymnosperms, ferns, and maybe angiosperms later on
thyreophoran brains
- stegosaurus and anklyosaur were not very smart
- olfactory bulbs were bigger than normal = well developed sense of smell
stegosaurs plates
- all stegosaurs had two rows of osteoderms embedded in their thick back hide
- also had smaller, flexible osteoderms covering their neck
- diverse array of plates, spikes, cones, etc, on the backs of different stegosauridae
stegosaurs plates for display
- come in two distinct forms - bigger and smaller
- bigger forms have bigger plates
- sexual dimorphism
- plates are species specific
- juveniles didn’t have them
stegosaurs plates for thermoregulation
- surface of the plates had grooves on them
- inside had a honeycomb structure
- suggested to be for blood vessels to warm/cool them
stegosaurs plates for defence
- plates made them look bigger (passive defence)
- more derived forms have an even greater difference between front and hind limbs, suggesting keeping the head low and the tail high was advantageous
stedosaurus tail
- tail was all defence
- thagomizer = paired spikes, directed outward on distal part of tail
anklyosaur timeline
rare in jurassic but abundant throughout cretaceous, much heavier armour than earlier thyreophorans
physical characteristics of anklyosaurs
- continuous shield of osteoderms from head to toe
- hind limbs longer than forelimbs, but not as big of a difference as seen in stegosaurus
- head a little lower and tail higher, eating vegetation
- leaf shaped teeth and a broad gut for digesting vegetation
- more derived forms had broader beaks, bigger guts, and tail clubs
evolution in anklyosaurs and the 2 main grups
diveristy increase in the cretaceous
1) anklosaurs
2) nodosaurs
anklyosaurs vs nodosaurs
anklyosaurs:
- heavily armoured
- tail club for derence
- small side spikes
nodosaurs:
- no tail club - more like a baseball bat
- bigger spikes on shoulders
anklyosaurs defence
- likely dropped their front even further and used their tail to target predators legs
- club made of bony scutes, sometimes with spikes
- stiff at end and flexible at the base = bone breaking force
label the ornithischian phylogeny
1 - hip bones, predentary bone
2 - dermal armour on their back
3 - pronounced diastem
4 - shelf at the back of skull
A - ornithischians
B - cerapoda
C - thyreophora
D - marginocephalia
E - ornithipoda
two marginocephalian dinosaurs
ceratopsia
pachycephalosauria
marginocephalia characteristics
“fringe heads”: shelf of bone by the neck
pachycephalosauria skull
very dense skull roof, with bone fiber oriented perpendicular to the outside
- skull designed to withstand very high impacts
were pachycephalosauria head bangers?
strong muscles in neck + brain oriented away from impact zone = designed for bashing heads
- variation in dome size and spikes related to age and developmental stage
evidence of display for pachycephalosauria head
- some evidence of blood vessels in the skull
- sexual dimorphism
pachycephalosauria feeding
- similar to thyreophorans
- leaf-shaped teeth
- big gut for fermentation
ceratopsia description
- cretaceous quadrupedal herbivores
- skull with narrow beak, flaring cheecks and frill
- variable development of frills and horns
basal ceratopsian characters
- bipedal
- narrow skull plares towards the back (frill)
- rostral bone
- more derived versions got bigger, and had post and ant orbital horns
protoceratops
- evolved in mongolia
- expanded frill and more massive skull
- body 2 m long
- chode
evolution of ceratopsians
- neoceratopsians evolve in early cretaceous in asia
- they disperse into north america and rapidly diversify in cretaceous
- increase in body size, post- orbital and nasal horns
- larger/ more diverse frills
- evolved dental battery
ceratopsian stance
two hypotheses:
1) sprawling stance (like other archosaurs) = slow
2) erect stance = not as slow
ornithischian development
- young appear to have stayed in the nest much longer than saurischians
ornithopods/euornithopods
- clade after ornithopoda
- bird feet with stiff tails
- diverse, numerous, and successful
- all 3 toed ornithischians, including hadrosaurs, and iguanodons
major ornithopod groups and characteristics
iguanodons and hadrosaurs
- long, stiff tails
- broad beaks and dental batteries
- basal forms were bipedal, derived quadrupedals still have similar structures
- rear limbs 2x longer than forelimbs: run quickly over long distance
- dexterous forelimbs, specialized hands
ornithopod feet
feet are symmetrically tree-toed, as in birds but group is NOT related to birds
iguanodon hands
- evolved a conical thumb spike
- digits 2-4 had hooves on them (bony pads for weight bearing)
- opposable pinky
hadrosaur hands
- lost digit 1 and 5, was too small to be opposable
- also had hooves on digits 2-4 = quadrepedal
- hadrosaurs became dominant herbivore in late cretaceous
ornithopod diets and feeding
- twigs, berries, angiosperms, and harder plant material
- hyper-herbivores = could snip and chew through any type of vegetation
- cropping beak
chewing in ornithopods
- multiple mobile components in the skull - complex and efficient mastication
- circular grinding in mouth
hadrosaur crest
- combination of sexual selection and communication
mass extinction occered when
end of paleozoic is marked by the largest mass extinction event in the history of life
-more than 90% of species disappear over a very short interval
extinction classification
by severity:
major = 50% families, 80-95 % species
intermediate = 20-30% families, 50% species
minor = 10% families, 20-30% species
K-PG extinction
- the cretaceous-paleogene extinction
- marks end of mesozoic
- at least 50% of all species lost, maybe >75 %
- on land: almost nothing over 25kg survives
- not just terrestrial species
5 pieces of evidence related to global iridium anomalies and extinction
iridium spike found at end of cretaceous rock boundary (before tertiary rocks)
1) fern spores vs pollen: massive spike in fern spores after K-PG, ferns are first to colonize fire impacted landscape
2) soot layers associated with the iridium layer: evidence of massive global fires
3) tektites: natural glass produced by melting rocks during impact
4) shocked quartz: another “impact” feature -> cross hatched lines = a stress line in the quartz crystal (shocked lamellae) - quartz crystal shattered up
5) tsunami deposits: evidence of almost global tsunami activity at end of cretaceous
the crater of K-PG
- 180 km across
- tsunami deposits, shocked quartz and tektites: thicker towards this structure
initial effects of meteor
vaporizes all close by/forest fires/ tsunamis
long term effects of meteor
- sunlight shut off - nuclear winter, photosynthesis stops on land and oceans - after dust clears, water vapor remans in the atmosphere = greenhouse effect
- these two effects combined = rapid shift in environmental conditions - cold months and hot years (decades)
was the impact the only cause of the extinction?
flood basalts in india: acid rain, ozone depletion, climatic greenhouse effects
what killed the dinosaurs?
- cretaceous biosphere already stressed
- KPG impact = the final nail in the coffin
- impact probably THE causal factor in extinction of dinosaurs
