Midterm 2 Sauropods Flashcards
True or False: Sauropoda contained the largest land animals of all time.
True!!
What two clades make up Sauropodomorpha?
Sauropods and Prosauropods
When were Sauropods at their peak in diversity?
Jurassic-Cretaceous transition
What tooth shape was characteristic of early sauropodomorphs?
Spatulate with serrations
The Sauropod hiatus refers to an absence of sauropods in which continent?
North America
When did sauropodomorphs originate?
Late Triassic
What does Opisthocoeleous mean?
Refers to vertebrae with a ball on the front and a cup on the back of the centrum in sauropod dinosaurs.
What are the evolutionary novelties of Sauropodomorpha?
heads small relative to their bodies, spatulate teeth, elongated vertebrae, very large claws on their forefeet, short feet
What does spatulate mean?
Spoon-shaped
What is the biggest difference between prosauropod and sauropods?
Prosauropods were basically built the same, but they were much smaller and more slender
True or False: Prosauropods are the ancestors of Sauropods
False. But they are closely related
Know the phylogeny of the Sauropodomorph clade
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Were prosauropods bipedal or quadrapedal?
They were likely obligatory quadrapeds
What modern day animal has teeth similar to those of the sauropodomorphs?
Iguana
What evidence suggests that sauropodomorphs were herbivores?
Jaw hinge, long necks, offset of the jaw similar to modern plant animals, mass of small stones in the stomach
What does Mussaurus mean?
Mouse lizard
What are the oldest known dinosaur eggs
Mussaurus eggs
What event coincided with the diverse speciation of sauropods?
The extinction of prosaurupods
What are some examples of sauropods?
Apatosaurus, Brachiosaurus, Diplodocus
Evolutionary Novelties of Sauropods
Gigantic size, long neck and tail, tiny head, dorsally located nostrils
What are the 3 distinct types of sauropods?
Diplidocoids, primitive macronarians, and Titanosauria (advanced macronarians)
Why is it normal to find sauropods without skulls?
Because they were relatively small and not connected to their spines very well.
What is it called when vertebrae are bound by two cavities?
Amphicoelous
What are Pleurocoels?
Deep side cavities
What was the function of Pleurocoels?
They helped to lighten the enormous sauropods. They may have had intricate air sacs or other materials that made them lighter.
What’s another name for the most primitive sauropods?
Eusauropods
Where were Diplidocoids primarily found?
Europe, North America, Antarctica
Evolutionary novelties of Diplidocoids
Long and slender skulls and muzzles, peg-like teeth at the front of mouth, nostrils on the top of skull above eyes, neck vertebrae had short ribs, neural spine had deep V-shaped groove
What is the humerus-to-femur ratio of a diplidocoid?
0.66
What is the astragalus?
Major bone in the ankle of Diplidocoids. It’s the ONLY bone in the ankle
How did the bones of Diplidocoids resist the weight of the animal?
They were packed with cartilage which resists pressure
What is the difference between diplidocoid chevrons and those of other sauropods?
Regular: Tuning fork shape
Diplidocoid: Look like 2 clothing hangers put together, rods extending from side
Brontosaurus or Apatasaurus?
Apatasaurus is the correct name because it was the first one used.
What does Macronaria mean?
Large nose
Evolutionary novelties of primitive Macronarians
Short heavy skull with a blunt snout, Jaws with large spatulate teeth, large nostrils on the sides of skull just in front of the eyes
What type of dinosaur is a Camarasaurus?
Primitive macronarian
What is the humerus to femur ratio of a camarasaurus
0.7
Famous macronarians?
Camarasaurus, brachiasaurus, haplocanthosaurus
Evolutionary novelties of Titanosaurs
proceloeus anterior tail vertebrae, widened sacrum, short and robust limbs, short forefeet, humerus and femur bowed out while walking (instead of being vertical)
What age were Titanosaurs prevalent?
Mostly the Cretaceous
Where did Titanosaurs live?
Mostly the areas that became the southern hemisphere
What is Procoelous?
In the vertebrae: When the socket is anterior and the ball is posterior
What is Opisthocoelous?
Vertebrae: Socket is posterior and ball is anterior.
Opposite of Procoelous
Amphicoelous
Vertebrae bounded by two cavities (instead of just having one cavity facing either posteriorally or anteriorally)
What are the two possible explanations for the sauropod hiatus in North America?
- We haven’t found the bones yet/bones were not preserved well
- Sauropods went extinct in NA in the early cretaceous and then migrated back up there 30 million years later (Alamosaurus)
True or False: Some Titanosaurs weighed more than a Boeing 737 airplane.
True… the airplane weighs 50 tons, an elephant weighs 5 tons, and some of the titanosaurs were 78 tons…
Blue whales weigh more though
What is the name of the giant sauropod vertebrae that Edward Cope found in the 1800’s?
And why is it significant?
Amphicoelius Fragillimuss
Supposedly the largest animal to ever exist, being 150 tons in total. But it’s possible that Cope may have incorrectly entered the height of the vertebrae he found (1.05 meters instead of 1.5)
What are the two types of sauropod teeth?
Spatulate teeth and peg-like teeth of the Diplidocoids
Homeothermy
Being able to maintain a constant body temperature
Thermal Inertia
Large dinosaurs take longer to warm up and have more trouble warming up because of their large mass.
Graviportal
Designed to bear great weight on land
Why did people think Sauropods were aquatic?
Because their bones couldn’t hold them up on land, their nostrils were on the top of their head, and their teeth could only chew soft aquatic vegetation
What is gregarious behavior and does it apply to sauropods?
Group activities, and maybe. There are tracks shown together, but nothing is conclusive.
Characteristics of the sauropod 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 pteradactyloid?
short tail, no teeth (beaks), mono-fenestra
Mono fenestra
fused external nares and anteorbital fenestra
Key characteristics of ramphorhycoid
long tail, teeth
Which is paraphyletic: pteradactyloid or ramphorhycoid?
Ramphorhycoid, does not include all descendants
What environment are most pterosaurs preserved in?
Marine/lacustrine environments
Fine grained sediments preserved soft tissue
Carnosaurs
Theropod: Meat lizards with short necks and small forelimbs
Coelurosaurs
Theropod: hollow tail lizards, smaller with long necks and long forelimbs
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 theoropod but does not have all of its evolutionary novelties
Theropod characteristics
Blade like serrated teeth
promaxillary fenestra
intramandibular joint
enlarged hands with grasping ability
predatory
feathered
bird-like feet
bipedal
lightly built skulls
What is the intramandibular joint for?
It’s an extra joint in lower jaw, allows for extra movement
What clade of theropods is most closely related to birds?
Coelurosauria
What are shared features of Coelurosauria and birds?
Enlarged brains, tridactyl hands with long second and third digit, feathers, hinge-like ankle
What are the major functions of the furcula?
Fused collar bones, strengthen skeleton, hold wings
What is the funtion of wings in non-flying taxa?
Insulation and/or display
Which theropods are known to be feathered?
Archaepteryx and Yutyrannus
Ceratosaurs distinguishing features
Theropod:
6 or more sacral vertebrae
Very deep coracoids
small forelimbs (maybe nonfunctional)
4 fingers
Examples of Ceratosaurs
Limusaurus, Aucasaurus, Abelisauroids
Carnosaur distinguishing features
Theropod
Extra opening in maxillary
Very large nasal bones
Examples of Carnosaurs
Allosaurus
Giganotosaurus
Coelurosaurus distinguishing features
Theropod
Most bird-like dinosaur
Enlarged brain
Boat shaped chevron bones
feathers
Tridactyl hand with long 2nd and 3rd digit
Examples of Coelurosaurus
Tyrannosaurus
Maniraptoriformids
Compsognathus
Unusual features of oviraptorids (theropod - enigmatic coelurosaurus)
Toothless jaw
Short snout
boxy skull
large fenestra in mandible
crest of sponge-like bone on tip of snout
Unusual features of therizinosaurs (theropod - enigmatic coelurosaurus)
Small skulls
long necks
huge claws
short legs
Using Plateosaurus as a representative prosauropod, describe the main characters of the group.
Small teeth with large serrations
Leaf shaped teeth
Short necks- not as long as sauropods
Feeding over wide arc
Jaw articulation offset– all teeth occluded simultaneously
Poorly pneumatized vertebrae
Obligate quadrupeds
Can be bipedal (more primitive feature)
No sharp claws
Know what anatomical evidence supports the notion that prosauropods were plant-eaters.
Long necks that feed over a wide arc side to side
Teeth look like modern Iguanas and are known as herbivores
Do not have sharp claws- not theropods (meat eaters)
Explain why most paleontologists exclude any known prosauropod from the ancestry of sauropods.
Because theropods are ancestors are sauropods, but they’re distinguished enough from sauropods that they have been given their own clade
Prosauropods have a small 5th digit
Compare and contrast the skulls of diplodocid, camarasaurid, brachiosaurid 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
Longer humerus than femur
Dip in pre-maxilla
Shunosaurus
Teeth facing forward
No dip in pre-maxilla like the brachiosaurus
Methods of developing long 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
Understand the significance of pneumatic vertebrae and their effect on the structure of the vertebrae in sauropods.
Added air so it was lighter
Keeps their necks strong but light
Allows them to feed with necks extended
Understand the relationship between skull size and neck length in sauropods
Smaller skulls= longer necks.
Know the evidence that suggests diplodocids could not raise their heads above the shoulders.
Necks were straight but heads were angled down, necks were not very flexible only side to side motions
Good for side to side, neck posture oriented down
Compare and contrast the feeding strategies of grazers vs high browsers.
High browser - longer humerus than femur, reaching into trees to feed from branches
Grazers - (no grasses, most likely ferns and other), low energy to graze on the ground, longer femur than humerus
Know when ornithischia lived and describe their distinguishing characteristics.
Self sharpening teeth, feathers, scales, have cheeks, ridges in maxilla and dentary
Longest lived dino-middle jurassic to end of cretaceous
Explain which ornithischians have asymmetrical tooth enamel, which clade is defined by this feature, and describe its function.
Neornithischia
Self-sharpening teeth
Thick enamel on the outside, thin on the inside
Know what features of the skeletons of different groups of ornithopods identify them as either bipeds or facultative bipeds.
Bipeds: Walks on 2 legs; much shorter forelegs. How the head is anchored.
Facultative bipeds: Walks on 4 but can on 2 for mating and eating; The head would be anchored more at the back of the head rather than the bottom so it is better for eating on all fours.
Prosauropods
Describe the hand of Iguanodon and its diagnostic features.
Thumb claw, spikey
Opposable pinky finger with 6 bones to grasp things with.
3 fingers to walk on like hooves
Compare and contrast the Hadrosaurine and Lambeosaurine clades of the Hadrosauridae
Both: extra motion to process food in jaw that grinds food
Hadrosaurine: heavily built, wide snouts, dental batteries, enlarged nares sometimes,
Lambeosaurines: crested skulls (impacted by age and sex), relatively lightly built, narrorwer snouts compared to hadresoaurine, dental batteries
Explain the specialized features of hadrosaurid skulls, particularly those related to feeding (beaks, diastema, cheeks, extra skull joints, tongue).
Diastema
Gap between beak/premaxilla teeth and back teeth
There so the tongue can bring food from the cheek to in the mouth
Cheeks
There to catch the food that falls out of the teeth during the grinding process
Extra skull joints
Allows teeth on maxilla to move back and forth
Better grinds the food
Beaks
Broad with no teeth
Know the function of the hollow tubes and crests on the lambeosaurine skulls.
Display and sound
Know which clade most likely had cheeks and the evidence to support this.
Evidence: ridges on skull above teeth is where cheek muscles would’ve connected
Clade: Ornithischians
Explain what the beak shape reveals about feeding habits.
Wider beak = grazer
Narrow beak = browsers
They’d use beaks to clip the vegetation before chewing it in their weird way. Likely grazed on horse tail like plants like thick and fuzzy grasses and leaves. Likely low browsers based on copperlites. But not grass, grass didnt exist until L cretaceous and wasn’t common even then.
