Dinosaurs! Class Study Guide-Exam 2

Which of the two clades of Dinosauria do theropods belong to?

Saurischia

Describe the characteristics of the Saurischian clade.

-Blade like serrated teeth
-Promaxillary fenestra
-Intramandibular joint
-Enlarged hands with increased grasping ability
-Bipedal
-Bird-like feet
-Lightly built theropod skulls
-Feathers
-Pneumatic bones

When did pterosaurs originate?

Late Triassic

When did Pterosaurs go extinct?

End of Cretaceous

What are key characteristics of the Pterodactyloid?

Mono-fenestra (fused external nares and ante-orbital fenestra), short tail, no teeth (beaks)

What are key characteristics of the Rhamphorhycoid?

Long tail, teeth

Which is paraphyletic; Pterodactyloid or Ramphorhycoid?

Rhamphorhynchoid, does not include all descendants

What environments are most Pterosaurs preserved in?

marine/lacustrine environments; fine grained sediments preserve soft tissue

Why are most Pterosaur bones crushed flat?

Hollow, pneumatic bones

Can you draw a cladogram showing the relationships in Archosauria between crocodylomorphs, pterosaurs, and dinosaurs?

Archosauria: Nests with vegetation; parental care of young; extensive vocal communication; parasagittal stance?; flow-through lung?

Crocodylomorphs: part of Pseudosuchia; enlarged calcanea tuber ("heel"); two rows of dorsal osteoderms

Pterosaurs: part of Ornithodira; cervicals distinct from dorsals; elongate tibiae and metatarsi; ? loss of boy armor

Dinosaurs: part of Dinosauromorpha; parasagittal stance? Hinge-like ankle joint AND Dracohors; elongate pubes and ischia

(picture of chart can be found on study guide)

How is Herrerasaurus related to Theropods?

One of the most primitive dinosaurs

Caused Saurischian and Ornithischian clades to split

Was originally thought to be a theropod but does not contain all of its features/evolutionary novelties

What are the features that are diagnostic of the theropods?

Blade like serrated teeth

promaxillary fenestra

intramandibular joint (extra joint in lower jaw, allows motion)

enlarged hands with increased grasping ability

Tyrannosaurus, Velociraptor, Allosaurus

Many were feathered

Bird like feet

Enlarged hand with pinky, 4 or 3 fingers with sharp claws, grasping hands with large claws

Theropod skulls are lightly built

Based on the features that are diagnostic of the theropods, what types of behavior can be inferred?

Bird like
Predatory
All bipedal

What are the bird-like features of theropods?

Head-neck joint (theropod skull was attached to the neck at a highly mobile joint), had bird-like feet, tail: changes midway from flexible proximally to being stiff distally, hollow, and light bones-kept the skeleton light and bones from bending

Which clade of theropods is most closely related to birds and what features do birds and this clade share?

Coelurosauria

Enlarged brains, Tridactyl hand with long second and third digit, feathers, hinge-like ankles

What is the major function of the furcula?

Fused collar bones

To strengthen skeleton and hold wings

Which theropods are known to be feathered and had wings?

Archaeopteryx
Insulation and/or display

What was the function of the wings in non-flying taxa?

insulation or display

How are ceratosaurs distinguished from other theropods?

Six or more sacral vertebrae

very deep coracoids

small forelimbs

very small, maybe nonfunctional

What are the distinguishing features of carnosaurs?

Feathers

Extra opening in maxillary

very large nasal bones

What are the distinguishing features of coelurosaurs?

most bird like dinosaur

enlarged brains

Tridactyl hands with long second and third digit

boat shaped chevron bones

feathers

What are the unusual features of enigmatic coelurosaurs, such as oviraptorids and therizinosaurs?

Therizinosaurs:
Small skulls
Long necks
Huge Claws
Short legs

Oviraptorids:
Toothless jaws
Short snouts
Boxy skulls
Large fenestra in mandible
Crest of sponge-like bone on tip of snout

Using Plateosaurus as a representative prosauropod review the main characters of the group.

-Small teeth with large serrations
-Elongated necks (feeding over wide arc)
-Jaw articulation offset-all teeth occluded simultaneously
-Poorly pneumatized vertebrae

What anatomical evidence supports the notion that prosauropods were plant-eaters?

Long necks that feed over a wide arc side to side

Jaw hinge below upper tooth row

Offset of jaws allowed parallel tooth rows to come in contact simultaneously

spatulate teeth, serrated

gizzard (small stones found in stomach to crush vegetation)

Explain why most paleontologists exclude any known prosauropod from the ancestry of sauropods.

Because theropods are ancestors to sauropods, but they're distinguished enough that they have been given their own clade

What are the two sauropodomorph groups?

Prosaurapoda and Sauropoda

What are the features that distinguish Prosaurapoda and Sauropoda from other dinosaurs?

very large; peg shaped teeth; teeth only in front; external nares pushed back on skull; long neck--pneumatic bones offset weight; oval/oblong leg bone cross section (lateral stress); lower jaw "hinge" (greater mechanical advantage when chewing)

Why are vertebrae in the shoulder region the most widely used diagnostic element in sauropod classification?

fragile skulls easily lost/destroyed after death so we can't rely on the skulls to classify species; intricate vertebrae vary great between sauropods

Compare and contrast the skulls of diplodocid, camarasaurid, and brachiosauri sauropods.

Diplodocus: only teeth in front and possibly a beak

Camarasaurus: rounded nose unlike Brachiosaurus that has a scooping nose

Brachiosaurus: enlarged nostrils above the eye, backwards L shape, dip in pre-maxilla

Shunosaurus: teeth facing forward, no dip in pre-maxilla like the brachiosaurus

How did the confusion about the name Brontosaurus resolve?

principle of priority (first name given is the name used)

What are the possible mechanisms for the development of long sauropod necks?

Robbing vertebrae from the back

Move shoulders back so dorsal vertebrae become cervical vertebrae

Adding extra vertebrae (happens only in early embryonic developmental)

Elongating individual vertebrae

What saurischian characteristics allowed sauropods to develop the longest necks of any vertebrates in the history of the earth?

Long neck:
-allows feeding over wide arc (side to side)
-are so long because vertebrae are so light (pneumatic)

Methods of Development:
-robbing vertebrae from the back
-move shoulders back so dorsal vertebrae become cervical vertebrae
-adding extra vertebrae (happens only in early embryonic development)
-elongating individual vertebrae

What is the significance of pneumatic vertebrae and their effect on the structure of the vertebrae in sauropods?

Added air so necks were lighter,

What is the relationship between skull size and neck length in sauropods?

Smaller skulls = Longer necks

What is the evidence that suggest diplodocids could not raise their heads above the shoulders?

Necks were straight but were angled down, necks weren't super flexible-only side to side motions

Compare and contrast the feeding strategies of grazers vs high browsers.

grazers, wide jaws, lots of food at once

browsers, more narrow jaws, "picky" eaters

When did ornithischian live and describe their distinguishing characteristics?

-lived: longest lived dinosaur, middle jurassic to end of cretaceous

-self sharpening teeth
-feathers
-scales
-cheeks

What are dental batteries?

teeth stacked on each other on sockets

How do dental batteries function?

dinosaurs grow and replace teeth throughout their entire lives, they are constantly replaced by these dental batteries.

What groups posses dental batteries?

sauropods, hadrosaurs, and ceratopsians, ornithischians

How did dental batteries allow ornithischians to be successful?

Constantly had new teeth, losing them wasn't a big deal, got worn down by chewing.

Which clade is first in Theropod phylogeny?

Ceratosauria

What was the main function of feathers on theropods?

Display

Which is among the most primitive theropods?
Staurikosaurus
Dimetrodon
Allosaurus
Herrerasaurus

Staurikosaurus
Herrerasaurus

Which clade is characterized by highly pneumatic (light) vertebrae, and primitive feathers?

Coelurosauria

Which clade is characterized by four fingered hands with sharp claws on first 3 digits?

Ceratosauria

Which clade is characterized by foramen in eye socket bone, and low spines at base of neck?

Carnosauria

Which clade includes primitive theropods, like Dilophosaurus?

Ceratosauria

Which is NOT a characteristic of Therizinosauria?

large teeth

What is true about Sauropods?

-Have air-filled (pneumatic vertebrae)
-Includes Camerasaurus
-long neck giants
-have VERY fragile skulls

What is FALSE about Prosauropods?

They are a monophyletic group.

What is a similarity of Prosauropods and Sauropods?

They are both clades of Sauropodomorphia

Why do paleontologists need permits to search for and collect vertebrate fossils on federal and state-owned lands?

-"keeps ya out of jail and out of trouble"-Brooks

-Helps protects the bones and know if there are bones of significance

What are the benefits of digital extraction of bones using CAT scanning vs mechanical bone extraction?

CAT scanning:
-high resolution
-put bones still inside of rock
-doesn't destroy specimen if you mess up the scan
-minute detail

Mechanical extraction:

What are the basic rules of naming animals? (It is the same for dinosaurs as it is for all other animals)

Whoever describes it in a technical jounral gets to name it first; genus must be unique, species can repeat;

What is the difference between taxonomic lumpers and splitters?

Taxonomic lumpers: groups several genera/species into one

Splitters: Think most discoveries are a new species

Why do many paleontologists end up teaching human anatomy at universities and medical schools?

few universities "need" a paleontologist, but they all need someone to teach pre-med or med-students anatomy

What is the paleoenvironment of the Saints and Sinners Quarry (Stratigraphic context)?

-Nugget Sandstone
-Based on radiometrically dated rock layers above and below the Nugget sandstone

What is the paleoenvironment of the Saints and Sinners Quarry (depositional environment)?

-Oasis in a vast desert, animals died during drought, bones in shallow water of oasis (buried by sand blown into lake)

What is age of the paleoenvironment of the Saints and Sinners Quarry

-Late Triassic and Early Jurassic (210 million years ago)
-based on Drepanosaurid and Procolophonid

True or false? Teeth of Diplodocidae are peg like.

True

True or false? Teeth of Camerasaurus are spoon shaped.

True

True or false? Sauropods necks elongate through the addition of vertebrae as ADULTS.

False

What is the use of long necks?

Feeding widely side to side

Besides their pelvic structure, what distinguishes Ornithischia?

Predentary bone

What is the evolutionary novelty distinguishing Neornithischia is?

Teeth with more enamel on one side than the other

What is the feature of multiple teeth stacked vertically and side-by-side?

Dental batteries

Which is a clade of Ornithischian dinosaurs?
Theropods
Sauropods
Ornithopods
Thyreophorans

Ornithopods
Thyreophorans

Which is NOT a characteristic of Ornithopods?
Predentary
Omnivores
Cheeks
Dental Batteries

Omnivores

What about dental batteries contributed to the success of Ornithopods?

Allow them to process much fibrous vegetation.

What are the three middle Iguanodon digits used for?

Walking

What is the fifth Iguanodon digit (pinky) used for?

Grasping

What is the first Iguanodon digit (thumb) used for?

Defense

Which is characterized by large size, toothless beaks, dental batteries, and no thumb?
Iguanodontids
Hadosaurids
Diplodicae
Hypsilophodontidae

Hadrosaurids

Hadrosauirids, "duck billed" ornithopods, contain two main variations:

Hadrosaurines and Lambeosaurines

Which is characterized by tubes and crests on their heads?
Hadrosaurines
Lambeosaurines

Lambeosaurines

What is the purpose of Lambeosaurines crests?

Display
Honking/Vocalizing

The diastema between the hadrosaur's beak and teeth provide evidence that?

The tongue could have been used to manipulate food

What does the additional joints in Hadrosaurs skulls provide evidence of?

They may have been able to move their jaws side to side

What evolutionary novelty distinguishes the Thyreophorans?

Boney plates in their skin (dermal ossicles)

What are the two clades of Thyreophorans?

Stegosauria
Ankylosauria

What are the evolutionary novelties that distinguish Stegosaurs?

Rows of large plates on back

True or false? Dermal ossicles were solid?

False

What filled dermal ossicle holes?

blood vessels

What is the difference between Ankylosaurids and Nodosaurid Ankylosaurs?

Nodosaurs have elongate snouts and no club on tail

What clade of Ornithischia is large headed and often horned?

Marginocephalia

Marginocephalia include

Ceratopsians and Pachycephalosaurs

Which is NOT true of Pachycephalosauria?

Divided into domed and non-domed

What do we now believe about non-domed Pachycephalosauria?

They are young juveniles

What does the image of damaged domes tell us about Pachycephalosauria?

Damage due to head butting

Which is NOT true of Ceratopsians?

They have dermal ossicles

What are the two main clades of Ceratopsidae?

Ceratopsinae
Centrosaurinae

Which is TRUE of Centrosaurinae (Pachyrinosaurinae) Ex. Pachyrhinosaurus?

Short face
Long nasal horn

Which is TRUE of Ceratopsinae (Chasmosaurinae) (ex. Triceratops)

Long face
Short nasal horn

Large bone assemblages of thousands of Ceratopsians tells us?

They traveled in herds

What caused the very backwards bent neck of a dinosaur skeleton?

Ligaments pulled the body into this pose after death

The animal was floating in water

Which describes bones that are in place when they are found?

Articulated

Which describes Continental Drift?

The continents were once together and have since drifted apart

What was a major concern of Continental Drift?

Wegener did not have evidence of a mechanism for movement

What event lead to the development of Plate Tectonics?

Mapping the sea floor topography