discovering dinosaurs midterm 2

saurischia

the smallest of dinosaurs and the largest animals that ever lived on land

agile and ferocious predator and the slowest and clumbsiest plant eaters

the smartest and the dumbest

aerial and earth bound

theropoda

saurischians that are not sauropods, worldwide distribution, monophyletic,

toothy carnovores eg t-rex

sauropoda

long necked herbavores

derived characteristic from Saurischia

Elongate cervical vertebrae Fossa expanded into the anterior corner of the external naris

Lacrimal expanded over the rear part of antorbital fenestra

A concave facet on the axial intercentrum for the atlas Elongation of the centra of anterior cervical vertebrae Distinctly large hand, loss of distal carpal V

Twisting of the first phalanx of manual digit I

Metatarsals overlapping

hands designed for grasping

Large size (almost half arm length), long fingers, distinctive thumb that falls across the palm instead of outwards

powerful feet

Large size (almost half arm length), long fingers, distinctive thumb that falls across the palm instead of outwards

ziphodont

"sword tooth" laterally compressed, with serrated cutting edges, recurved

knife like teeth

killing machines

packs of highly social, sharp-eyed, large-brained, agile small theropods, armed with grasping hands and slicing claws.

obligate bipeds

unable to walk or run on anything but their hind legs

cursorial

having limbs adapted for running

digitigrade

foot is supported by its toes

walking on toes

plantigrade

Walking on the soles of the feet and heels

shorter femur than tibia

a condition typical of fast-running bipeds

how fast can theropods move

fastest theropods- 40-60kmh

stroll-4kmh

large theropods- 40kmh>

clawed feet

good for attacking prey

extreme extension

semi opposable 1st digit

can grasp

theropod heads

proportionally large

Tyrannosauroids--deep-jawed skulls with a powerful bite

Carcharodontosaurus-- had much more lightly built skulls toothless ornithomimosaurs noncarnivorous therizinosaurs-- had proportionately smaller heads, toothed

how do theropods eat

without chewing their food

teeth are for puncturing and slicing

large theropod teeth

recurved teethkeep prey from e

scaping mouth

accomodated the geometry of theropod jaw--when jaw closed it could more efficiently puncture

curved towards back, straighter more towards the from

small theropod teeth

pointed serrations, narrow cross-section

Sliced

Mineral crystals of tooth enamel arranged in a simple pattern

teeth were subjected to uniform stresses

Tyrannosauroid Teeth

Bulbous teeth w/ rounded serrations

Weaker cutting ability, but greater bite power

strong for holding prey

Enamel has a complex pattern of crystal orientations

bone crushers

teeth replace themselves-like sharks

gastroliths

common in Ornithomimosaurs

kept in the gazzard- stones ground down unchewed plants for better digestion

peg-like projections on palate

suggests that its jaws were designed to feed on hard objects that required crushing, such as clams, oysters, and mussels

theropod vision

a 55° range of binocular vision

large eyes for sharp vision

theropod hearing

good sound perception

able to hear low frequency sounds

able to identify direction of sound

zygapophyses

supportive processes on each vertebra that prevent twisting

give the tail rigidity, enabling it to move as a unit in any direction from the articulation near the base of the tail

key element of balance

theropod brains

significant cerebral powers

troodontids had the largest brain to body size of any nonavian theropod

complex perceptual ability and more precise motor-sensory control

types of prey

•Compsognathus --> Sinosauropteryx (lizards and mammals), Baryonyx (fish), Daspletosaurus (hadrosaurid bones)

Coprolites: •Tyrannosaurus-sized poo containing 30 to 50% bone fragments

Tooth marks on bones of triceratops and edmontosaurs

Spinosaurus

flattened foot bones, larger hands and arms then other theropods of its size, sharp, conical teeth

aquatic

gender features

sexually dimorphic

morphologic differences and colour for sexual selection

display- frills, horn, crests

Melanosomes

cells that produce color in feathers, whose shape gives an indication of some of the colors in non-avian theropods.

Neotheropoda

3 toed foot with one off ground

furcule present

furcula

single bone composed of the two clavicles (collar bones) fused together, is the familiar "wishbone" of chickens and turkeys

tetanuraw

inflexible tail- beyond the base, the tail doesnt bend

teeth only at front of jaw

proportionally large hands

pleurocoels

internal system of cavities in the skeleton

pneumatic foramina

Openings in the bones of birds for extension of the air sacs. Diverticuli from the air sacs will extend into most of the bones of the skeleton via these holes

Unidirectional respiration

inhalation: air enters the trachea and posterior air sacs-- expand. Air is moved to lungs, where it is deoxygenated, and stored in anterior air sacs, which expand and fill with deoxygenated air.

Exhalation: the deoxygenated air in lungs and anterior air sack, is expelled via contraction out of the trachea

Avitheropoda

(avis - bird, a reference to bird-like features of many members of this group)

2 clades- carnosauria, coelurosauria

Carnosauria

carn - meat, includes some very large dinosaurs such as the allosaur and carcharodontosaur

Coelurosauria

(coel - hollow), includes both small and large forms, most famously the tyrannosauroids

convergent evolution

Process by which unrelated organisms independently evolve similarities when adapting to similar environments

Compsognathidae

lightly build; highly cursorial (having limbs adapted for running); bladed, recurved teeth suggesting carnivory, however insectivory is also a possibility

Ornithomimosauria

(orni - bird; mimus - mimic), highly cursorial, mostly medium-sized, long legs, small heads, large eyes, toothless

more or less veggie eaters

Maniraptora

(manus - hand; raptor - stealer), contains everything else within Coelurosauria

• Proportionately longer forelimbs • Bony sternum

• Semi-lunate carpal

Oviraptorosauria

didnt look like their relatives the therizinosaurs

highly successful, lived throughout the Cretaceous, started with teeth, but by the Late Cretaceous, were without teeth.

paraves

Comprised of the last two groups of highly predaceous and crazily intelligent maniraptorans: Deinonychosauria and Avialae

extremely long arms and hands, wings made up of multiple layers of quill-like feathers, backwards facing pubis, large retractable sickle claw on the second digit of the foot.

Deinonychosauria

2 main clades: dromaeosauride and roodontidae

Dromaeosauridae

smart, social, gracile bones, large claws, powerful hands, locked tail

Troodontidae

enigmatic, distinctive teeth

sickle shaped claw, large brains, stereoscopic vision, rigid tail, grasping hands

avialae

(all living birds + Archaeopteryx)

fused scapula and coracoid; humerus longer than scapula; ulna longer than femur (again, a character indicating extremely long arms); ≤ caudal vertebrae.

arboreal hypothesis

suggests that bird flight evolved by "birds" gliding down from trees

cursorial hypothesis

suggests that bird flight evolved by "birds" running along the ground until the animals became airborne

Synsacrum

Fusion of the pelvic girdle and vertebral column

pygostyle

the fused terminal vertebrae of the spine, supports the tail feathers

carpometacarpus

fusion of the distal bones in the wing

keeled sternum

helps to increase power, large flight muscles attach here, when breastbone has extra length in skeletal terms

Sauropodomorpha

relatively small skull

delicate lower jaw

elongate lanceolate teeth with coarsely serrated crowns

very long neck

big thumb

elongate femur

nuchal ligament

Helps to stabilize head and allows shoulders and head to be more independent. Allows improved balance during running

opisthopubic

part of the pubis rotated backward to lie close to or parallel with the ischium

predentary

an unpaired scoop-shaped element that capped the front of the lower jaws

3 sections of a herbivorous mammal

Cropping part at the front, with blade-like incisors

A gap, or diastema, that is toothless

Cheek teeth, or molars (in mammals)

Rhamphotheca

keratinized covering of beak

keratin

protein-based substance that makes up horns, nails, hooves, and claws.

jugal

cheek bone

scutes

A bony external plate or scale, as on the shell of a turtle or skin of a crocodilian

Nodosauridae

Relatively long snouts, well-muscled shoulders (reflected by acromial process, a large knob of bone on the shoulder blade), many had tall shoulder spines (parascapular spines), no tail club

Ankylosauridae

well armored, fewer tall spines along body, tail ends in massive bony club, head shorter and broader, large triangular plates attached to the rear corners of the skull (squamosal horns)

convolute nasal sinuses

running from the external nasal opening towards the braincase. were involved in a heightened sense of smell