Final Cards Flashcards
what is a theropod?
= all saurschians that aren’t sauropods
- mostly bipedal
- claws
- serrated teeth
describe theropod walking
Harrow legs with one foot nearly in front the other
Horizontal, with head and tail balanced over pelvis
Tail never touched the ground: no tail trackmarks
femurs in theropods
some evolved short femurs compared to the tibia to increase speed (ornithomimids)
describe theropod grasping claws
semi-opposable thumbs that could grasp prey - in dromaeosaurs and troodontids, second digit held erect, until attacking (3 toes, 4th up and sticking backwards)
describe theropod arms
three fingered hands are most common
- four digits in more primitive theropods, and some derived forms only had 2
myths about theropod arms (3)
1) they are small
- only small related to body
2) they are weak
- might have been able to lift heavy and had huge claws
3) they were useless
- options such as mating, grasping prey
theropod jaws
carnivorous theropods had larger heads, with powerful bites compared to herbivores (theropods or not)
carnivore vs herbivore jaws
carnivores had slicing, scissor like jaw that was designed to cut through prey, not chew vegetation. Herbivorous ornithischians had grinding jaw for chewing
theropod teeth
- curved backward to hold prey
- serrated for greater cutting ability
- more rounded = less for slicing and more for crunching
not all had huge teeth:
- ornithomimids had beaks for grinding small vegetation
- short jaws for crushing (shellfish)
theropod vision
- theropods had generally excellent vision
- eyes facing forward and overlapping = stereoscopic (3D similar to us but worse)
- also has shortened snouts, to help increase range
theropod brains
had the largest brains compared to body size in dinos
sexual dimorphism
the difference in appearance (colour, size, shape, structure) between males and females of the same species
- some evidence of ornamentation, but could’ve also been colourful
- some medium and smaller theropods were multi coloured with feathers
feathers
many dinosaurs had some sort of feathers. the point when these evolved is continuously being pushed further back. most of the adaptations needed for flight happened for other reasons first.
some of these feathers are not flight feathers, but for display, insulation, and other reasons
types of feathers
1) hollow, hair like filaments (mono filamentous feathers)
2) loose, unconnected barbs (downy feathers)
3) hooked barbs on vane (contour feathers)
4) asymmetrical vane with hooked barbs (flight feathers)
uses for feathers
1) insulation
2) display
3) flight
limb to wing transition
in the fossil record, we can see changes in the size, number, and fusion in the digits of theropods
three main hypotheses for the origin of flight
1) tree down
- climbing and gliding
- claws used for climbing
2) ground up
- running and leaping
3) the compromise
- started by helping them run
what kind of hip structure is this?
saurischian
what kind of hip structure is this?
ornithischian
theropod diversity
- first dinosaurs may have been saurischians with the basic theropod appearance
- there was rapid diversification during late triassic
- sauropods split from theropods a bit later (still in late triassic)
the earliest theropod genus
herrasaurus
herrerasaurus description
walked on all four hind toes, but more advances theropods (neotherapoda) walked on only the middle three with digit 1 greatly reduced
- boxy shull and bad 3D vision
neotheropods
- one of the next clades after theropoda
- loss of fifth digit on feet and development of furcula (wishbone; two collar bones fused together)
only in birds today
coelophysis
- taxon of neotherapoda
- late triassic - early jurassic
- smallish, fast and agile, pack-hunting carnivore
- four digits on hand, but one was embedded in the hand