Week 1 - Appearance and Anatomy Flashcards
What is a paleontologist?
A person who studies dinosaurs
What does the term ‘fossil’ mean?
“dug up”, any evidence of ancient life
What era did dinos live in?
Mesozoic era
How are bones considered adaptations?
- resist gravity and maintain an animal’s form
- provide a rigid framework for muscle attachment
- provide protection and can be major components of horns and other weapons
- bones store minerals such as calcium
Why are bones more likely to fossilize?
They do not rot away as quickly as muscle fibres, hair or feathers
What is an adapatation?
Features or traits that serve particular functions and are the result of evolution
What are the descendants of dinos?
birds
What sauropods are the tallest, longest, and heaviest?
tallest = giraffatitan
longest = diploclocus
heaviest = argentinosaurus
Why is mass hard to estimate?
- skeletons are usually not complete
- bones are mineralized –> heavier
- don’t have other tissues
- like birds, often have extensive air sac systems throughout their body
What are defining characteristics of vertebrates?
have a spine and skull
What are the major fenestrae found in vertebrates, specify where they are found in dinos
- orbits = eye openings
- nares = nose openings
- laterotemporal fenestrae = behind the orbits of dinos, lateral side
- supratemporal fenestrae = behind the orbits of dinos, on top of skull
- antorbital fenestrae = between each orbit and naris of dinos
What is the brain case? Where is it located, any notable features?
- brain case = hollow chamber formed by multiple bones that houses the brain
- found in the rear of skull
- contains small holes for nerves to pass through
What makes up the axial skeleton?
vertebrae
What are the components of vertebrae?
vertebrae = centrum + many posthesis + hole
- centrum = disk
- prosthesis = attach muscle
- hole = room for spinal cord
Where is the neural arch found and what does it do?
- found = above centrum
- function = covers the neural canal
What is the neural canal?
opening through which spinal nerves run through
What are the functions of vertebral prosthesis? What are the different prosthesis and where are they found?
Functions:
- attachment for muscle
- surface for ribs
Types of prosthesis:
- transverse prosthesis –> extend from lateral side of the vertebrae
- spinous prosthesis –> extend upwards from the neural arch
What are the different vertebrae called?
- neck vertebrae = cervical
- back vertebrae = dorsal
- hip vertebrae = sacral
- tail vertebrae = caudal
What are differences between mammalian ribs and dino ribs?
- mammals don’t have ribs in the rear portion of our body, dinos have ribs all the way to their pelvis
- mammals don’t have gastralia (body ribs), dinos do
What do the shapes of vertebrae represent?
adaptations for flexibility and posture
What bones are found underneath caudal vertebrae and what do they do?
Chevrons –> protect a large blood and nerve channel and provide support for tail muscles
What makes up the appendicular skeleton?
limbs - arms and legs
How are arms and legs connected to the rest of the body?
via limb girdles:
- pectoral/ shoulder girdle
- hips/pelvis girdle
What is the scapula?
shoulder socket
What is the acetabulum?
hip socket
what do the shapes and proportions of bones in our body represent?
adaptations to the environment
describe how the arm bones are similar and different between a human and tyrannosaurs
Similarity:
-same bones in humans and tyrannosaurs - humerous = upper arm bone –> same location and function in humans
- radius + ulna = lower arm bone that attach to humerous and wrist (carpals)
Differences:
- tyrannosaurs arm is bigger and has two main fingers
- phalanges in tyrannousaurs = two outer fingers became smaller and eventually disappeared, same with the middle finger (seen as a thin bone in the palm)
- large claws on fingers (fingernails in humans
Describe the leg bones of dinos
- femur = upper bones
- tibia and fibula = lower bones
- ankle (tarsals) = small and support long feet bones (metatarsals)
- toes (phalanges): inside = small and doesn’t touch the ground; 2nd, 3rd, and 4th toes = support dinos weight; outer toe = lost in dinos
What is the advantage of walking on your toes?
helps dinos take longer steps and run faster because leg length was effectively longer
What are the three bones that make up the pelvis of dinos and which bone divides dinos into saurischians and ornithischians?
- ilium
- pubis (diff in saurischians and ornithischians)
- ischium
Describe the features of the ilium (i.e which hip bone is it, functions, anatomical features)
- upper hip bone
- sacral vertebrae are fused here = sacrum
- muscle attatchments at font –> go to the front of the leg and pull the leg forwards
- muscle attachments at back –> go to tail and back of leg and pull the leg backwards
Describe the features of the pubis (i.e which hip bone is it, functions, anatomical features)
- middle hip bones
- supports weight of animal when squatting on the ground
- attaches muscle
- in ornithischian dinos, the pubis reorientates itself back beside the ischium
Describe the features of the ischium (i.e which hip bone is it, functions, anatomical features)
- lower hip bone
- attaches and orientates muscle
Describe the orientation of the pubis bone in saurischians and ornithischians and if they are bird-hipped or lizard-hipped
Saurischians:
- lizard-hipped
- pubis facing foward
Ornithischians:
- bird-hipped
- pubis facing backward (might have small projection facing forward)
Describe the defining features of sauropods
- largest land animals to exist
- long necks and tails
- walked on all fours
- limb bones are thick and look like columns
- vertebrae are complex and many of them have cavities for air sacs
- skulls are small compared to the rest of their body
- teeth are simple and peg-like
Describe the defining characteristics of theropods
- highly diverse –> carnivores (sharp teeth vs toothless beaks), omniovores, herbivores, long snouts vs short snouts, horns over eyes vs over nose
- walked on hindlegs
- modern birds evolved from theropods
- usually have 3 clawed fingers, but some had two fingers (e.g. T rex), or a single claw
Describe the defining features of prosauropods
- early group of herbivores
- smaller
- small heads and lock necks
- grasping hands
- walked on hind legs
Describe some general features of ornithischians
- bird hipped dinos (evolutionary convergence)
- special bone in lower jaw = predentary
- all herbivores
What are some ornithischian adaptations to a vegetarian lifestyle?
- predentary = forms a cropping beak in the front of the mouth –> slice off plant stems –> allowed teeth to become specialized for grinding and chewing (dental batteries)
- backward pointing pubis –> more room for a larger GIT –> digest tough plant matter
Describe some features of hadrosaurs
- duck billed dinos
- some bipeds and some quadrapeds
- complex dentations for shearing and grinding plants (broad beaks)
- flat vs elaborate crests on heads
- hand encased in a mitten of skin
Describe some features of igaunodons
- evolved complex dentations for shearing and grinding plants (broad beaks)
- had a spiky thumb
Describe some features of ceratopsians
- quadrapeds
- shorter tails
- frills at back of head
- horns and spikes can develop on frills
- many have horns over their eyes
- narrow skulls
- parrot like beak
Describe some features of pachrhinosaurus
- ceratopsian
- nasal boss over its nose
- superorbital boss
Describe some features of pachycephalosaurs
- high dome skull –> mostly bones, used as a marker to recognize each other, battering rams
- smol brain
- shorter legs –> don’t run fast
Describe some features of stegosaurs
- 4-legged –> front legs shorter than back
- small, long, narrow skull
- teeth are leaf-shaped
- narrow beak
- plates/spikes along the back –> formed via osteoderms
- long tail –> spikes at the end
Describe some features of ankylosaurs
- armoured dinos –> osteoderms of many sizes and shapes
- 4-legged
- round fat bodies
- blocky shaped
- small, leaf shaped teeth
- some had tail clubs
How do we know that a dino has been mummified vs fossilized?
mummified dinos are rare and have lots of skin associated with the dino
What are claws, beaks and feathers made of, and what is a consequence of this?
keratin - harder than flesh, but still rarely fossilized
Name and describe some examples of feathered saurischians
Sinosuaroptyrex
- theropod
- body had feathers –> body was buried in volcanic ash –> preserves soft tissues
Yutyrannus
- large tyrannosaurid with feathers
Name and describe some examples of feathered ornithischians
Psitiacosaurus:
- ceratopsian
- long bristle like structure on its tail
Tianyulong:
- had long filaments over most of its body
Kulindadomeus:
- bristle-like filaments
- branching feather like structures
Why is volcanic ash and mud good for preserving details?
alters the chemistry of the water –> prevents decomposition by bacteria
What dinos have we found scaly impressions of?
hadrosaurs, ceratopsians, ankylosaurs, stegosaurs, sauropods, don’t have impressions for pachycephalosaurs
Describe characterisitics of osteoderms
- formed completely within the dermis
- cros and armidillos have osteoderms
- some sauropods have osteoderms
What are the advantages of osteoderms?
- store calcium
- gathers heat from sun (some had skin and blood vessels)
- protection from bites and clawing predators
- to look good
What is feather colour influenced by?
the shape and arrangement of pigment cells called eumelanosomes
Describe the different known arrangements of eumelanosomes and what colour they correspond to
- long and narrow –> black and grey
- short and wise –> brown and reddish brown
- none –> white
- narrow and aligned in same direction –> iridescence
What lines of evidence tell us about muscles in dinos?
- coprolite (poopies) from a tyrannosaur have the remains of muscle fibres
- some fossils have preserved cartialginour tracheal rings in the throat and muscle fibres in the base of the tail
- looking at the bones
Describe how tyrannosaur bones have demonstrated soft anatomy
Upper arm bone:
- can see striations where muscles attach to the bone
- scars on bone –> where muscles attached and that those were powerful muscles
Femur:
- crest by the head –> lever for muscle attatchment to pull the dino forwards
Describe how different positions of jaw muscles vary
- e.g jaw muscles of tyrannosaurus are relativley short and broad and attached to the lower jaw muscle in a way to maximize bite force
- e.g. longer jaw muscles of gigantosaur –> less powerful bite, but can close its jaws much faster
