lecture 15 Flashcards
What does theopoda mean?
beast foot
What are the characters of the therapoda? (5)
- are bipedal
- active runners
- have knife-like teeth
- have extra openings in front of the antorbital fenestrae called the promaxillary fenestrae
- have large hands with grasping abilities
How do therapods move away from the classical characteristics we think of them having?
They evolve omnivory and herbivory, are very toothy to toothless, have diverse ecology and morphology, range from the size of a small bird to a t.rex
Are birds living theropod dinos? How?
Yes, they are the lineage of therapods that survived the end cretaceous mass extinction 65 million years ago
What is the most diverse group of terrestrial vertebrates? How many species?
birds, have nearly 10,000 species
How did hollow bones help therapods as predators? Do birds also have these?
The limb bones of theropods were hollow and likely housed air sacs, the combo of light skeleton and unidirectional breathing made them very active predators
Why are therapods so diverse?
They were around the entire age of the dinos so Diversity in therapod habitats led to diversity in morphology of theropods
What is the global distribution of therapods?
They have been found on every single continent, rom virtually every kind of terrestrial environment
What are the seven main groups of therapods, start from primitive to most derived?
Therapoda
Neotheropoda
Tetanurae
Avetheropoda
Coelurosauria
Maniraptoriformes
Maniraptora
All other therapods outside the herrerasaurus are what?
neotheropoda
What are the three characteristics of the neotheropods?
Lose digit 5 (pinky) on hand
functionally 3-toed foot (fourth toe suspended in air)
have the furcula present
What is the difference between the theropod and the ornithopod footprint?
Theropod footprint has claws, slender toes, longer foot then wide, more of a v shaped outline
The ornithopod footprint has blunt rounded tips, wider toes, wider foot than long, and has a more u shaped foot outline
What is the furcula? What does it do?
Is a wishbone/clavicle, it strengthens the thorax but also acts as a spring which allows for efficient flight
How does the furcula act like a spring and allow for more efficient flight?
When breast muscles contract, the furcula expands, energy is released when the furcula snaps back to normal position which helps lift wings
What else does the furcula aid in outside of strengthening thorax and helping flight?
Aids in respiration, helps to pump air through the air sacs.
Why was it hard to identify dinos as the ancestors of modern birds?
Because we couldn’t see the furcula preserved
What did the discovery of the furcula do to change our perception of the therapod body plan?
moved the arms from out to the side towards the front of the body
Large neotherpods frequently had what on their heads?
elaborate head ornamentation
The ceratosauria belong to which clade? What were they named for?
They’re named for having cranial ornamentation and belonged to the neotheropoda
What were the characters of the tetanurae?
All have an inflexible tail, all have interlocking zygopophyses on tail vertebrae
What are zygopophyses?
projections from neural arches
What group of dinosaurs are within the tetanurae?
The megalosauroidea and spinosaurus
What dinosaur was the first to be named? What clade is it in?
Is in the tetanurae, is the megalosaurus
Spinosaurus and it’s relatives (belonging to tetanurae) are considered what? Why?
crocodile mimics, because they have a croc like snout and conical teeth- the teeth are not laterally compressed
