Lesson 1 Flashcards
T/F
All large reptiles that are extinct are known as dinosaurs
false
dinosaurs have a very specific definition!
the definition of a dinosaur is determined by anatomical details in the ______
eg
skeleton
eg air sinus present, hind legs: ankles move to tuck their legs underneath
who invented the term ‘dinosaur’? When?
Sir Richard Owen
170 years ago
- no complete dino skeletons had been found at this point!
bones had been found from 3 different dinosaurs at the time that Sir Richard Owen invented the term dinosaur. What were the 3?
- What were they previously described as?
megalosaurus, iguanodon, hylaeosaurus
- extinct giant reptiles
What do megalosaurus, iguanodon, & hylaeosaurus all have in common?
- teeth that grew out of sockets (like modern crocodiles)
- erect limbs (like modern mammals, birds)
Suggested these 3 creatures were more related to each other than to any modern reptile, so created ‘dinosauria’ group
___ are more likely to fossilize than other body structures
bones
paleontologists look at what to determine how many dino species there were?
- also to understand how ecosystems changed through time and adaptations of each species
the skeletons
______, or “long-necked dinos” include the largest animal that ever walked the earth
sauropods
Which of the following was the largest sauropod?
- argentinosaurous
- diplodocus
- giraffatian
depends on the definition of ‘large’!
- gieaffatitan= tallest dino
- diplodocus= longest
- argentinosaurous= heaviest
how is the weight of a dino estimated?
extrapolation based on comparison of limb proportions of the dino compared to those of large modern mammals whose weights can be measured directly
Why is it hard to estimate how heavy a dino was based on its fossils?
- usually incomplete skeleton
- only includes bones, no organs/ muscles etc
- bones have been infiltrated w/ minerals= heavier
- some had air sacs, which would make them much lighter than an equivalently sized modern mammal
the smallest dinos were smaller than a _____!
t/f
lots of these were meat eaters
chicken
true!
t/f
humans and dinos have basically the same skeletons with the same bones in the same places
why or why not?
true!
because we’re all vertebrates, so have a common ancestor
which of the following are vertebrates?
- humans
- sharks
- octopus
- snakes
all except octopus
what are the openings for the eyes in a skull called?
orbits
what are the openings for the nose in a skull called?
nares
openings in the skull that aren’t for the nose or eyes are called _____, which means ____
fenestrae
window
fenestrae are important for distinguishing between major _____ of _____
lineages of vertebrae
the antorbital fenestra will be ____ (in front of/ behind) the orbit, and the laterotemporal fenestra will be ____ (in front of/ behind) the orbit
antorbital = in front
laterotemporal = behind
where would the super temporal fenestra be located?
on top of the skull
t/f
neck vertebrae are different from back vertebrae
true
neck vertebrae are called ____
back=
hip=
tail=
neck= caudal
back= sacral
hip= dorsal
tail= cervical
t/f dinos don’t have ribs in the rear portion of their body
false!
dinos had ribs all the way to their pelvis
- mammals are unusual and do not have ribs in the rear portion of our body
_____ are “belly ribs” and are not found in mammals. They’re an adaptation for flexibility and posture
gastralia
your arms and legs connect to the rest of the body via the ___ ____
- for arms: ____ ______
- for legs: ______ ____
limb girdles
shoulder girdle
hip/ pelvic girdle
t/f
the bones of different animals may take different shapes, but the same kinds of bones will be present
true
give some similarities and differences between human vs tyrannosaurus arm bones
similarities:
- same bones are present! humerus, radius, ulna, and metacarpals present in both
differences
- dino has bigger arm
- dino only has 2 main fingers compared to our 5
- dino had large claws on fingers, while ours were replaced with fingernails
do humans and dinos share the same leg bones? which?
yes!
upper= femur
2 lower= tibia and fibula
t/f
Like most dinosaurs, all Tyrannosaurus walked on their toes and the soles of their feet were elevated off the ground.
true
sacral vertebrae are fused to the ___
hips
the first major division of dinos is based on the shape of the ___
pelvis
What are the 2 groups called that divide dinos based on pelvis shape?
- saurischia (lizard hipped dinos)
- irnithischians (bird hipped dinos)
did birds evolve from saurischia or irnithischians?
confusingly, birds evolved from lizard hipped dinos, not bird hipped dinos.
= saurischia
all dinos have __ pairs of bones that make up their pelvis
3
what’s the largest bone in a dino body?
ilium (in the pelvis)
explain the main 4 bones of the dino pelvis and briefly what they do
- sacrum= fused to vertebral column, designed to support great weight
- ilium= upper bone (largest in the body). pull the leg forward and back
- ischium= smaller bone beneath ilium: goes down and back
- pubis: goes down and forward. different in saurischians vs ornithischians
What’s the easiest way to tell a ornithischian from a saurischian dino based on the pelvis?
the pubis bone:
in ornithischians, the pubis reorientates itself so it’s back beside the ischium.
in saurischians, the pubis has a huge boot on the bottom to support weight
The saurischians can be divided into 2 major groups:
- sauropods (long-necked dinos)
- theropods (very diverse!)
- carnivores, herbivores, etc
t/f
all theropods walked on their front legs
false
all theropods walked on their hind legs
_____ were an early group of plant- eating dinos and were much smaller than their giant sauropod cousins (some were still massive)
Prosauropods
Prosauropods
- ___ heads and ___ necks
- ___ hands
- ability to stand and walk only on their __ feet
- successful at first, but had a __ reign
small, long
grasping
hind
short
there are two key traits that distinguish all ornithischians from thischians:
- ornithischians have a hip with a pubic bone that points backwards
- ornithischians have a special bone in the lower jaw, called the predentary. No other animals have one.
These adaptations were for a vegetarian lifestyle
the backwards pointing pubic bones of Ornithischians resembles those of birds.
Does this mean they’re closely related?
No, it’s an evolutionary convergence, so there is no close relationship
how did the predentory bone help with herbivory?
helped to form a cropping beak in the front of the mouth= tool for slicing off plant stems
how did the backwards pointing pubis give ornithischians an advantage as herbivores?
gave extra belly room for an enlarged digestive tract (plant matter is difficult to digest!)
t/f
ornithischians were all omnivores
false
they were all herbivores
what are the 5 main lineages of ornithischians?
- duck-billed hadrosaurs
- ceratopsians
- dome-headed dinos (pachycephalosaurus)
- stegosaurus
- ankylosaurs
ornithopods=
___-hipped dinos that typically walk on __ legs and are _____(herbivores/ carnivores)
bird
2
herbivores
ceratopsians walk on __ legs and have ___ at the back of the head, made up from elongated bones from the back of the skull
4
frills
what is a boss?
a bony mass
- can be nasal, supraorbital, etc
eg. pachyrhinosaurus has both
t/f
the dome-headed dinos had a very large brain
false
the large head was just bone, not brain :(
likely used the domes to recognize each other and/or headbutting
stegosauria walked on __ legs, although their ___ legs were shorter than their __ legs
4
front shorter than hind
what is the most distinguishing characteristic of stegosauria?
osteroderms= the plates/ spikes along the back –> formed from a special type of bone that forms in the skin
ankylosauria are known as the “_____ dinos” and have ___-shaped skulls.
They are covered in ___ of different sizes, and sometimes have a huge one at the end of the tail to form a ___ ____
armoured
block
osteoderms
tail club
t/f
muscles, organs, and skin of dinos are never preserved, so we don’t actually know the true appearance of any dino
false
although organs etc decay much faster than bones, sometimes we can get an idea of appearance from well-preserved tracks with scales etc
also, sometimes the body was covered with mud shortly after dying, so skin impressions were left before rotting away
mummified dinos=
dino skeletons with lots of associated skin (rare!). large regions of skin hanging off the bones
first found in wyoming in 1910
keratin (beaks, claws, etc) almost ‘fossilized’
integumentary structures=
The integumentary system includes the epidermis, dermis, hypodermis, associated glands, hair, and nails
t/f
sometimes integumentary structures revealed in the fossil record reveal an adaptation we never would’ve guessed a dino would have
true!
t/f
very few dino groups besides birds had feathers
false!
many dino groups did
eg. feathered velociraptor
what is the impact of volcanic ash on fossilization?
like mud, it preserves fossils very well.
however, it also alters the chemistry of the water, and bacteria can’t live in it, so feathers, etc are preserved
which of the following most likely had feathers based on evidence?
- tyrannosaurus
- edmontosaurus
- stegosaurus
- velociraptor
definitely velociraptor, probably tyrannosaurus too
for which group do we currently not have any skin impression?
pachycephalosaurs
do both ankylosaurus and stegosaurus have osteoderms?
yes!
what might be some benefits of having osteoderms?
-storing calcium (eg in sauropods)
- gathering heat from the sun (if the osteoderm was covered in skin/ blood vessels)
- protection from biting/ clawing predators
- to look good! (eg stegosaurus flaunting it)
mostly as protection though
scales, feathers, bristles, and osteoderms are called ______ _______
integumentary structures
what are eumelanosomes?
an arrangement of pigment cells that determines feather color in modern birds.
none= white
long & narrow= black and grey
this is a proxy to see what color dino feathers might’ve been!
t/f
evidence for dino colors of blue, green, and red have been found
false
no evidence for those colors existing
Do we have any idea what color dino skin might have been?
no
can’t use eumolanisomes for skin, only feathers
what does osteoderm mean?
“skin bones”
b/c these are bones that are formed completely within the dermis (lower layer of skin)
we don’t have anything like this!
from a ______, or dino dropping, from a tyrannosaur, we have the remains of muscle fibers
coprolite
the best evidence for soft anatomy of a dino comes from looking at the _____
bones
- can see striations where the muscles attached to it
____ are the descendants of dinos and ____ are the second cousins of dinos. Why is this useful in trying to understand muscles in dinos?
birds
crocodiles
if we find the same muscles attached to the same points/ bones in both birds and crocs, we can infer that those were the same muscles attached to those points in dinos
how do we know what tyrannosaurus teeth looked like?
there are tooth imprints in bone (they were strong enough to bite through bone!)
_____ has the strongest bite of any animal, alive or dead
t-rex
compare the jaws/ bites of t-rex vs gigantosaurus
gigantosaurus had longer skull and lower jaw
= less powerful bite than t-rex, but could close its jaws much faster
