Geol 120 Vocabulary Exam 3

air sac

thin-walled, hollow structures connected to the lungs in many dinosaurs, aiding in efficient breathing and possibly regulating body temperature

argentinosaurus

one of the largest known land animals ever, this titanosaurian sauropod lived in South America and could reach over 100 feet long

bipedal

walking on two legs, a common trait among many theropods and early dinosaurs

ceratopsia

a group of herbivorous dinosaurs known for beaked faces and often elaborate frills and horns

Cope’s rule

a hypothesis that lineages tend to increase in body size over evolutionary time due to advantages in predation and resource acquisition. This trend is observed in various animal groups.

facultative biped

an animal that can walk on two legs when needed, but usually moves on all fours

furcula

this fused clavicle bone is found in birds and some dinosaurs; important and some dinosaurs; important in flight mechanics and muscle attachment

hadrosauridae

“duck-billed” dinosaurs; herbivorous and often very social, with complex crests used for communication

herbivore

an organism that primarily eats plantsand is adapted to digest plant material.

iguanodontidae

a family of large, plant-eating ornithopods, including Iguanodon, known for their thumb spikes and semi-quadrupedal stance

maiasauria

a hadrosaurid dinosaur whose name means “good mother lizard”; evidence suggests it cared for its young in nests

maniraptora

a group of theropods that includes birds and bird-like dinosaurs with grasping hands and often feathers

marginocephalia

a clade of dinosaurs including ceratopsians and pachycephalosaurs, characterized by a bony shelf or frill at the back of the skull

opisthopuby

a pelvic structure where the pubic points backward, found in ornithischians and birds important in digestive and balance adaptations

ornithischia

one of the two main divisions of dinosaurs, all herbivorous, with a “bird-hipped” pelvis

ornithopoda

a subgroup of ornithischians known for agility and complex chewing, includes hadrosaurs and iguanodonts

pachycephalosauria

dome-headed dinosaurs that likely used their thick-skulls in head-butting or display behaviors

pennaceous feathers

the stiff-vane like feathers seen in modern birds; present in some theropods, indicating flight or display functions

pleurokinesis

a type of skull flexibility allowing dinosaurs to process plant matter more efficiently

prosauropods

early, mostly bipedal relatives of the giant sauropods; transitional forms between small bipeds and huge quadrupeds

protoceratops

a small, frilled ceratopsian from Mongolia; key to understanding dinosaur nesting and reproduction

quadrupedal

walking on all four limbs

rostral bone

refers to the front part of the head/skull; in ceratopsians, the rostral bone forms the upper part of the beak

saurischia

the “lizard-hipped” dinosaurs, including theropods and sauropodomorphs

sauropodomorpha

long-ecked herbivorous dinosaurs, ranging from smaller forms to massive sauropods that include features such as long necks and tails, a relatively small head, and elongated limbs.

sauropods

giant- quadrupedal herbivores with long necks, and tiny heads that lived during the Mesozoic era and were known for their massive size and long tails.

semilunate carpal bone

a crescent-shaped wrist bone in maniraptoran theropods, allowing wing-like motion, is crucial for the evolution of flight

spinosauridae

a family of theropods with crocodile-like skulls and often semi-aquatic habits

spinosaurus

a large, possibly aquatic theropod with a sail-like structure on its back; one of the longest known carnivorous dinosaurs that lived during the Late Cretaceous period, characterized by its elongated snout and adaptations for hunting in water.

tetanurae

a major subgroup of theropods, including most carnivorous dinosaurs and birds, is characterized by stiff tails and advanced limb mechanics

theropoda

bipedal, mostly carnivorous dinosaurs; includes T. rex, Velociraptor, and modern birds

thyreophora

armored dinosaurs, including stegosaurs and ankylosaurs, are known for their body plates, spikes, and clubbed tails that provided protection against predators and exhibited a diverse range of sizes and shapes.

tyrannosauridae

the group that includes Tyrannosaurus rex and is relatively large, apex predators with strong jaws and robust bodies, known for their powerful bite and significant size in the dinosaur clade.

ziphodont teeth

blade-like, serrated teeth found in carnivorous reptiles like theropods, designed to slice flesh efficiently

what are the two branches of marginocephalia?

pachycephalosauria and ceratopsia

what are the two main branches of ornithopoda?

iguanodontidae and hadrosauridaeare the main branches of this dinosaur clade, characterized by their herbivorous diet and varied body shapes.

what are the two main branches of Saurischia?

theropoda and sauropodomorpha

what is the use of the interlocking caudal vertebrae in tetanurae?

it served as a dynamic stabilizer, helping these dinosaurs turn faster and maintain balance

how did the tyrannosaurids modify their body to become better active hunters?

their eyes were move forward, their brains got progressively larger, and the visual cortex expanded with improved hearing.

what was the purpose for the thickened skull rood in pachycephalosauria?

they have a high incidence of cranial injuries and the thickened skull roof likely served as protection during intraspecific combat.

how did hadrosaurs modify their teeth for effective chewing?

hadrosaurs developed broad, flat teeth that were continuously replaced, allowing them to efficiently grind and process tough plant material.

what are the main synpomorphies for saurischian dinosaurs?

elongated cervical vertebrae, predentary bone, toothless tip of snout, 5 sacral vertebrae, forward-facing pubic bone. They also have hollow air sacs that make their body lighter.

what group of dinosaurs were major herbivores that first appeared in the late triassic?

sauropodomorpha

what is the largest dinosaur?

the argentinosaurus that lived during the late Cretaceous period

what group of dinosaurs were a major group of carnivores that first appeared in the late Triassic and were exclusively bipedal?

theropoda

what group of dinosaurs first appeared in the early cretaceous and went extinct in the late cretaceous?

pachycephalosauria

what group of dinosaurs first appeared in the late jurassic and went extinct at the end of the cretaceous?

ceratopsia

what group of dinosaurs first appeared in the middle jurassic and went extinct at the end of the cretaceous? they are known as the “hitch-hiker” diinosaurs.

iguanodontidae

what group of dinosaurs first appeared in the middle jurassic and were strictly carnivorous?

tyrannosauridae