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paleontology
study of all prehistoric life
a paleontologists knowledge of prehistoric life comes primarily from ….?
fossils
fossil
any preserved evidence left behind by a prehistoric organism
literally means “dug up”
usually objects or structures found buried in ancient rock formations
what can dinosaur fossils include
footprints
eggshells
coprolites (fossil poop)
and sometimes skin and feather impressions
bones (most common)
why do bones have a greater chance of preserving?
theyre made of minerals
T/F: modern birds are considered to be dinosaurs
true
why is it hard to determine the weight of dinosaurs
fossils collect minerals
other aspects of the dinosaur have decomposed
air sacs in fossils
adaptations
traits that have evolved because they serve specific functions
what are the four major functions bones serve?
resisting gravity and maintaining the animals form
provide a ridged framework for muscle attachment
provide protection and can be components of weapons (horns)
store mineral reserves
are dinos vertebrates or invertebrates?
vertebrates
vertebrates
animals that have two special kinds of adaptations: skulls and vertebrae
vertebrae
structures made primarily of bone and/or cartilage that surround a portion of the spinal nerve cord
they interlock with each other in a series and form the vertebral column
what types of animas were the first vertebrates?
aquatic animals
invertebrates
animals that lack vertebrae
are there more invertebrates or vertebrates?
invertebrates
are vertebrates or invertebrates generally larger?
vertebrates
brain case
hollow chamber formed by multiple skull bones that houses the brain
rear portion of the skull
has many openings to allow nerves to pass through that connect to the brain
size and shape indicate the size and shape of the brain it housed and can provide clues to the dinos mental capabilities
nares
pair of openings for the nostril
orbits
pair of openings for the eyes
fenestrae
additional skull openings in dinosaurs
laterotemporal fenestrae
the fenestrae on the lateral sides of the skull
behind the orbit
supratemporal fenestrae
fenestrae on top of the skull
behind orbits
what is the purpose of the laterotemporal fenestrae and the supratemporal fenestrae?
providing extra room for large jaw muscles
antorbital fenestrae
located between each orbit and naris
function unclear
may have helped them breathe or adaptations to make the skull lighter
centrum
spool/disk shaped body of a vertebra
neural arch
cover the neural canal
neural canal
opening in each vertebra through which the spinal nerves run
vertebral processes
provide attachment surfaces for muscles and sometimes provide articulation surfaces for ribs
two common types of vertebral processes
transverse processes: extend from the lateral sides of the vertebrae
spinous processes: extend upwards from the neural arch
cervical vertebrae
vertebrae in the neck
often have extra large openings for blood and nerve channels and are adapted to support the weight of an animal’s head
dorsal vertebrae
vertebrae in the back
often have tall spinous processes and large rib articulation surfaces
sacral vertebrae
vertebrae in the hips
pelvic bones are fused to the sacral vertebrae
sacrum
the single solid bone formed when the sacral vertebrae fuse
further increases strength of hips
caudal vertebrae
vertebrae in the tail
chevrons
protect a large blood and nerve channel and provide support for tail muscles
underneath causal vertebrae
in dinos, _____, ________, _______, and ______ vertebrae may all support ribs
cervical, dorsal, sacral, caudal
what are the largest ribs in dinos?
those that connect to the dorsal vertebrae and form the ribcage
in dinos all dorsal vertebrae connect with the ribs (in mammals the dorsal vertebrae close to the hips do not)
gastralia
small ribs positioned across a dino’s underbelly, underneath the ribcage
tetrapods
animals that evolved from an ancient ancestor with four feet and four limbs
some have hands instead of feet (humans)
some have no limbs at all (snakes)
includes dinos, mammals, reptiles, and amphibians
limb girdles
connects limbs of tetrapods to the rest of the skeleton
pectoral girdle
where forelimbs connect
aka shoulder girdle
scapula
largest bone in each side of the pectoral girdle
aka shoulder blade
pelvic girdle
where hindlimbs connect
aka hip bones
what are the three bones of the pelvic girdle
ilium
pubis
ischium
these bones are tightly connected to one another
ilium
upper hip bone
sacral vertebrae fuse here
pubis
below ilium
positioned in front of the ischium (near belly)
ischium
positioned behind the pubis, nearer the tail
acetabulum
depression or the hole in the pelvic girdle into which the hind limb articulates
humerus
bone between the shoulder and elbow
largest bone in the forelimb
radius and ulna
parallel bones between the elbow and the wrist
radius is the thinner one
carpals
bones in the wrist
metacarpals
bones between the wrist and fingers
phalanges
finger bones
femur
bone between the kip and knee
largest bone in the hindlimb
fibula and tibia
two parallel bones between knee and ankle
tibia forms the shin
fibula is the one that’s usually broken (thinner)
tarsals
bones in ankles
metatarsals
bones between ankles and toes
phalanges
bones in the toes
T/F: patterns of bones are largely the same in all tetrapods
true
T/F: dinos only walked on their toes
true
allowed them to take longer steps and run faster
what are the two major groups of dinosaurs
saurischians and ornithiscians
saurischians
dinos that share an evolutionary ancestor that had a pubis that extended downwards and forwards (towards the ribcage)
"lizard hip”
ornithischians
dinos that share an evolutionary ancestor that had both a special beak-forming bone in the upper jaw (predentary) and a pubis that extended downwards and backwards, towards the tail
“bird hip”
are birds saurischians or ornithischians
saurischians that have changes their hips from extending forward to extending backward
what are the two major groups of saurischians
sauropodomorphs
theropods
sauropodomorphs
large herbivores with elongated necks and relatively small heads
prosauropods
sauropods
prosauropods
an early group of sauropods and were the first group of large-bodied herbivorous dinos to evolve
sauropods
later group of sauropodomorphs
gigantic
stood on four robust and column-like legs
cervical vertebrae filled with air sacks to reduce weight
simple and peg-like teeth
theropods
bipedal
shared a carnivore ancestor
most:
carnivorous
blade like teeth
sharp hooked claws
some:
herbivorous
lack teeth
birds are a kind of therapod
ornithischians
backward extending pubis
allows more space in the ribcage to better digest plants
herbivorous
have beaks (to eat plants better)
what are the 5 major groups of ornithischians
ornithopod
pachycephalosaurs
ceratopsians
stegosaurs
ankylosaurs
ornithopods
lack armour
walked bipedally all the time or just wen running
many were small but some were big
iguanodonts
large ornithopods with a spike-shaped claw on each hand
hadrosaurs
duck billed
boney crests
large beaks
dense, tightly packed teeth that form large chewing surfaces
dental batteries
pachycephalosaurs
bipedal
short arms
unusually stout and strong tails
armoured skulls
thick dull domed skull roofs and backward pointing horns (fighting with each other)
sharp conical teeth in the front of their mouths and leaf shaped teeth in the rear
omnivores
ceratopsians
large parrot-like beaks
skulls that expanded into the rear (large boney frill or neck shield)
quadrupedal and have short tails
triceratops
large ceratopsian
stegosaurs
group of quadrupedal dinos with rows of projecting osteoderm plates down their backs and long osteoderm spikes on their tails (and sometimes backs and shoulders)
osteoderms: bones that develop within the skin (armour)
front limbs ae shorter than hind limbs (not fast runners) but they could probably pivot quickly and could rear up and stand on their hind legs
small heads
narrow snouts
integument
dinos body covering
difficult to know this because they decay rapidly
keratin
tough but flexible material that also composes hair, feathers, fingernails, and the outside of claws, beaks, and horns
increases likelihood of fossilization
sinosauropteryx
therapod dino whose feathers were preserved
dinos body was buried in ash from volcano
how we know some small therapods had feathers
yutyrannus
largest known feathered dino
what are some examples of dinos suggesting that ornithiscians could have had feathers like therapods
psittacosaurus
bristles on tail
tianyulong
long filaments all over body
kulindadromeus
feather- like structures on tail
melanosomes
pigment cells within a feather
can be observed in some fossil feathers and give clues to dinos true colours
what do black and grey colours result from
long and narrow melanosomes
what do brown and reddish colours come from
short and wide melanosomes
what does white come from
no melanosomes
what does iridescence come from
narrow melanosomes aligned in the same direction
scipionyx
preserves the mineralized remains of the trachea