Lesson 1: Appearance and Anatomy

Question 1

What is paleontology?

Answer 1

the study of dinosaurs is a subdivision of the branch of science known as paleontology

it is the study of prehistoric life

a paleontologist’s knowledge of prehistoric life comes primarily from fossils

Question 2

What is a fossil?

Answer 2

a fossil is any persevered evidence left behind by a prehistoric organism

means “dug up”

fossils are usually objects or structures found buried in ancient rock formations

dinosaur fossils include footprints, eggshells, coprolites (fossil poop), and in rare instances even skin and feather impressions

most dinosaur fossils are bones

Question 3

Why are most fossils comprised of bones?

Answer 3

bones are partially made of minerals, which do noy decay as easily as flesh and other soft tissues

for this reason, bones have a much greater chance of being preserved as fossils

Question 4

How can the sizes of dinosaurs be compared to modern animals?

Answer 4

although birds are the smallest dinosaurs that we know of, we still have many examples outside this group of living dinosaurs that were no larger than a house cat

Question 5

Why is it hard to accurately estimate the weight of dinosaurs?

Answer 5

dinosaurs filled with air sacs like birds so it’s hard to estimate weight

Question 6

What are adaptations?

Answer 6

traits that have evolved because they serve specific functions

Question 7

How are bones adaptations that help an animal survive?

Answer 7

bones passively resist gravity and maintain an animal’s form

bones provide a ridged framework for muscle attachment

bones provide protection and can also be major components of horns and other robust weapons

bones store mineral reserves

Question 8

What are vertebrates?

Answer 8

are animals that have two special kinds of skeletal adaptations: skulls and vertebrae

fish, amphibians, turtles, snakes, birds, and mammals are all examples of vertebrates

Question 9

What are vertebrae?

Answer 9

structures made primarily of bone and cartilage that surround a portion of the spinal nerve cord

together, vertebrae interlock with each other in a series and form the vertebral column

Question 10

What are invertebrates?

Answer 10

animals that lack vertebrae

include animals like insects, spiders, snails, squids, clams, jellyfish, and worms

Question 11

Why are vertebrates more numerous when it comes to species of large animals?

Answer 11

this success is probably related to the vertebral column’s ability to passively support weight and to anchor enlarged muscles

Question 12

What is the skull?

Answer 12

the skull is not a single bone

rather, the skull is made up of many bones that are tightly locked together

Question 13

What are the upper and lower jaws in the skull?

Answer 13

the upper and lower jaws may contain teeth and/or include a beak, and they are critical for interpreting what a dinosaur was adapted to eat

Question 14

What is the brain case?

Answer 14

is a hollow chamber formed by multiple skull bones that houses the brain

there are many small openings into the brain case

nerves pass through these opening and connect to the brain

the size and shape of a brain case can indicate the size and shape of the brain case can indicate the size and shape of the brain that it housed, and , therefore, can provide clues to a dinosaur’s mental capabilities

Question 15

What are the nares openings in the skull?

Answer 15

the nares are the pair of openings for the nostrils

Question 16

What are the orbit openings in the skull?

Answer 16

the orbits are the pair of openings for the eyes

Question 17

What are the fenestrae openings in the skull?

Answer 17

additional skull openings

behind each orbit, dinosaurs have two fenestrae

Question 18

What are the laterotemporal fenestrae in the skull?

Answer 18

fenestrae on the lateral sides of the skull

Question 19

What are the supratemporal fenestrae in the skull?

Answer 19

fenestrae on the top of the skull

Question 20

What is the function of the laterotemporal fenestrae and supratemporal fenestrae?

Answer 20

provide extra room for large jaw muscles

Question 21

What are the antorbital fenestrae in the skull?

Answer 21

between each orbit and naris

the function is unclear

they may have simply been adaptations that made dinosaurs skulls lighter, or they may have also housed large sinus cavities that helped warm the air that dinosaurs breathed

Question 22

What is the vertebral column?

Answer 22

is comprised of a series of interlocking vertebrae that begins with the first vertebra in the neck and ends with the last vertebra in the tail

Question 23

What is the centrum?

Answer 23

spool or disk shaped body on the vertebra

Question 24

What is the neural arch?

Answer 24

above the centrum

covers the neural canal

Question 25

What is the neural canal?

Answer 25

is the opening in each vertebra through which the spinal nerves run

Question 26

What are vertebral processes in the vertebra?

Answer 26

extending from the centrum or neural arch provide attachment surfaces for muscles and sometimes provide articulation surfaces for ribs

Question 27

What are transverse processes in the vertebra?

Answer 27

extend from the lateral sides of the vertebrae

Question 28

What are spinous processes in the vertebra?

Answer 28

extends upwards from the neural arch

Question 29

What are cervical vertebrae?

Answer 29

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

Question 30

What are dorsal vertebrae?

Answer 30

vertebrae in the back dorsal vertebrae often have tall spinous processes and large rib articulation surfaces

Question 31

What are sacral vertebrae?

Answer 31

vertebrae in the hips because the pelvic bones in terrestrial vertebrates serve as solid anchors for powerful leg muscles, the pelvic bones are fused to the sacral vertebrae

Question 32

What is the sacrum?

Answer 32

to further increase the strength of the hips, the sacral vertebrae are also fused with one another and form a single solid bone structures called the sacrum

Question 33

What are caudal vertebrae?

Answer 33

vertebrae in the tail

Question 34

What are chevrons?

Answer 34

underneath caudal vertebrae are bones called chevrons chevrons protect a large blood and nerve channel and provide support for tail muscles

Question 35

In dinosaurs, how do the vertebrae support the ribs?

Answer 35

cervical, dorsal, sacral, and caudal vertebrae may all support ribs the largest ribs are those that connect to the dorsal vertebrae and form the ribcage in dinosaurs, all dorsal vertebrae connect with ribs

Question 36

What are gastralia?

Answer 36

"belly ribs" small ribs positioned across a dinosaur's underbelly, underneath the ribcage

Question 37

What are tetrapods?

Answer 37

animals that evolved from an ancient ancestor with four feet and four limbs most tetrapods still have four feet and limbs, although some, like humans, have hands instead of front feet and some, like snakes, have lost their limbs altogether

Question 38

What are limb girdles?

Answer 38

the limbs of a tetrapod are connected to the rest of the skeleton by limb girdles

Question 39

What is the pectoral girdles?

Answer 39

the forearms connect to the pectoral girdle

Question 40

What is the scapula?

Answer 40

is the largest bone in each side of the pectoral girdle

Question 41

What is the pelvic girdle?

Answer 41

the hindlimbs connect to the pelvic gridle each side of the pelvic gridle is composed of three bones that are tightly connected to one another

Question 42

What is the ilium?

Answer 42

the upper hip bone it is to the ilium that the sacral vertebrae are fused below the ilium are the pubis and the ischium

Question 43

What is the pubis?

Answer 43

is positioned in front of the ischium, nearer the belly

Question 44

What is the ischium?

Answer 44

is positioned behind the pubis, nearer the tail

Question 45

What is the acetabulum?

Answer 45

is teh depression or (as in dinosaurs) the hole in the pelvic girdle into which the hind limb articulates

Question 46

What is the humerus?

Answer 46

between the shoulder and elbow is the largest bone in the forelimb, the humerus

Question 47

What are the radius and ulna?

Answer 47

between the elbow and wrist are two parallel bones, called the radius and ulna in most tetrapods, the radius is the thinner of the two

Question 48

What are carpals?

Answer 48

the bones in the wrists

Question 49

What are the metacarpals?

Answer 49

the bones between the wrist and fingers

Question 50

What are phalanges?

Answer 50

finger bones

Question 51

What is the femur?

Answer 51

between the hip and knee is the largest bone in the hindlimbs, called the femur

Question 52

What are the fibula and tibia?

Answer 52

between the knee and the ankle are two parallel bones, called the fibula and tibia

Question 53

What is the tibia?

Answer 53

the bone that forms our shin the thinner of the two lower leg bones

Question 54

What are the tarsals?

Answer 54

bones in the ankles

Question 55

What are the metatarsals?

Answer 55

bones between the ankle and toes

Question 56

What are Saurischian dinosaurs?

Answer 56

those that share an evolutionary ancestor and had a pubis that extended downwards and forwards, towards the ribcage

Question 57

What are Ornithischian dinosaurs?

Answer 57

those that share an evolutionary ancestor that had both a special beak-forming bones in the upper jaw (called the predentary) and a pubis that extended downwards and backwards, towards the tail

Question 58

What are the two major groups of saurischians?

Answer 58

sauropodomorphs and theropods

Question 59

What are sauropodomorphs?

Answer 59

were large herbivores with elongated necks and relatively small heads

Question 60

What are prosauropods?

Answer 60

were an early group of sauropodomorphs and were the first group of large-bodied herbivorous dinosaurs to evolves

Question 61

What are sauropods?

Answer 61

were a later group of sauropodomorphs many sauropods attained truly gigantic size, and the group includes the largest animals to ever walk the earth they stood on four robust and column-like legs sauropod vertebrae (particularly the cervical vertebrae) are filled with complex air sacks, which helped reduce weight the teeth of sauropods are usually simple and peg-like

Question 62

What are theropods?

Answer 62

were bipedal saurischian dinosaurs that shared a carnivorous ancestor many theropods were carnivorous and have serrated blade-like teeth and sharp hooked claws, but some were herbivorous and a few lack teeth altogether birds are a kind of theropod, making theropods the only group of dinosaurs that is not completely extinct

Question 63

How is the backwards extending pubis found in ornithischians an adaptation?

Answer 63

created more space in the ribcage this extra space was probably filled by extra-large digestive organs

Question 64

What are the characteristics of ornithischians?

Answer 64

plant matter is much harder to digest than meat, and most herbivores need larger stomachs and intestines than do carnivores all known ornithischian dinosaurs are thought to have been primarily herbivorous the beaks are also herbivorous adaptations that helped ornithischians to chop off large mouthfuls of vegeation

Question 65

What are the five major groups within ornithischians?

Answer 65

ornithopods pachycephalosaurs ceratopsians stegosaurs ankylosaurs

Question 66

What are ornithopods?

Answer 66

include a wide range of dinosaurs that lack armor and that either walked bipedally all the time or assumed a bipedal stance when running many ornithopods are small antelope-sized dinosaurs, but some, like the iguanodonts and hadrosaurs, grew to be multi-ton giants

Question 67

What are iguanodonts?

Answer 67

are large ornithopods with a spike-shaped claw on each hand

Question 68

What are hadrosaurs?

Answer 68

"duckbilled dinosaurs" hadrosaurs evolved late in the history of dinosaurs, but were highly successful some hadrosaurs have elaborate boney crests, and all hadrosaurs have strikingly large beaks in the front of their mouths and dense, tightly packed rows of small teeth in the rear of their mouths together, these teeth form large chewing surfaces and are collectively referred to as dental batteries

Question 69

What are pachycephalosaurs?

Answer 69

were bipedal with short arms, unusually stout and strong tails, and armored skulls some pachycephalosaurs have thick, domed skull roofs and backwards pointing horns they may have rammed predators or have butted heads with each other in competitions for territory or mating rights have sharp conical teeth in the front of their mouths, behind their beaks, and leaf-shaped teeth in the rear these front teeth have led to the hypothesis that they might have been omnivores

Question 70

What are Ceratopsians?

Answer 70

are another group that evolved late in the history of dinosaurs have large parrot-like beaks and skulls that are greatly expanded in the rear this rear skull expansion is taken to an extreme and a large boney frill, or neck shield, is present have large horns and also possess dental batteries Triceratops is easily the most famous of the ceratopsians and is one of the largest most were quadrupedal and have short tails

Question 71

What are stegosaurs?

Answer 71

are a group of quadrupedal dinosaurs with rows of projecting osteoderm plates down their backs and long osteoderm spikes on their tails some stegosaurs also have osteoderm spikes on their backs and over their shoulders front limbs are much shorter than their hind limbs heads are small relative to their bodies and their snouts are narrow

Question 72

What are osteoderms?

Answer 72

bones that develop within the skin and are a common component of animal armor

Question 73

What are ankylosaurs?

Answer 73

the most heavily armored of all dinosaurs are quadrupedal with short legs and wide ribcages the backs and skulls of most ankylosaurs are covered in spikey protective osteoderms some ankylosaurs also have large osteoderms on the ends of their tails, forming a mace or "tail club" unlike their relatives, the stegosaurs, most ankylosaurs have short snouts and broader, rounded beaks

Question 74

What is integument?

Answer 74

body covering

Question 75

How can skin impressions be preserved in fossils?

Answer 75

skin impressions from other regions of a dinosaur's body can be preserved if a dinosaur was covered by mud shortly after it died and before its flesh rotted away direct fossilization of skin and other soft parts is also possible, but such instances are exceedingly rare

Question 76

Why is the scaly skin of dinosaurs more likely to be perserved?

Answer 76

the scaly skin of dinosaurs has a slightly better chance of being fossilized than would our own skin, because scales are coved by a substance called keratin

Question 77

What is keratin?

Answer 77

is a tough but flexible material that also composes hair, feathers, fingernails, and the outside of claws, beaks, and horns

Question 78

What was the major breakthrough in the study of dinosaur integument in 1996?

Answer 78

a small therapod specimen with fossil feathers was discovered in Liaoning, China this little carnivorous dinosaur called Sinosauropteryx the feathers had been preserved, because the dinosaur's body was buried suddenly by extremely fine ash from a volcano

Question 79

What aremelanosomes?

Answer 79

pigment cells within a feather under microscopic examination, melanosomes can be observed in some fossil feathers, and they give clues to a dinosaur's true colors black and gray colors results from long and narrow melanosomes brown and reddish colors come from short and wide melanosomes white feathers have no melanosomes

Question 80

How can the muscles of dinosaurs be interpreted from fossils?

Answer 80

one of the major functions of bones is to provide attachment surfaces and a rigid frame work for muscles the shapes of bones often correspond to particular muscle shapes muscles often leave behind scars on the surfaces of bones where they are attached