Midterm 2 Theropods Flashcards
What does Theropoda mean?
Beast foot or mammal foot
True or False: Most meat eaters belong to the Theropoda clade.
True
When were the Theropod dinosaurs on earth?
Late Triassic to Cretaceous (entire span of dinosaurs)
Was a Tyrannosaurus Rex a Theropod?
YES!
Theropods are the most diverse group of dinosaurs. What modern group of tetrapods is the most diverse?
Birds
What does carnosaur mean?
Meat lizard
What does coelusaur mean?
hollow-tailed lizards
What does ceratosaur mean?
Horned lizards
What clade of theropods are birds descended from?
Tetanurans
Be able to draw the basic Theropod phylogeny.
k
What does Tyrannosaurus Rex mean?
King of the Tyrant Lizards
What does Allosaurus mean?
Different lizard
When was the term Theropoda introduced?
1881
Who coined the term theropoda?
Othniel Charles Marsh
What does Ornithopoda mean?
Bird foot
Who coined the name Ornithopoda?
Othniel Charles Marsh
When was the name Ornithopoda introduced?
1871
What does Sauropoda mean?
Lizard foot
Who coined the name Sauropoda?
Othniel Charles Marsh
When was the name Sauropoda introduced?
1878
What does Stegosaur mean?
Plated lizards
What did Marsh use to classify dinosaurs?
Foot structure
What is the strange controversy that came up relating to the foot structure of theropods and ornithopods?
Theropod means beast feet but those dinosaurs have bird-like feet, and ornithopod means bird feet but those dinosaurs have mammal-like feet…. so it seems like Marsh mixed the two up accidentally.
Why is it hard to classify theropods and identify a standard phylogeny?
Because the group is so diverse.
What evolutionary novelties are used to distinguish theropods from other archosaurian animals?
They were highly specialized runners and predators, exposure of lachrymal bone on the skull roof, a joint within the jaw, a sacrum comprising at least 5 vertebrae, clavicles fused into a wishbone (furcula), 4 or fewer digits on the hand, and a unique hind foot that is compact, narrow, and long with three functional digit and another separated from the rest.
What is a furcula?
Wishbone
True or False: Theropods had the largest and most sophisticated brains of any dinosaurs.
True
What was the primary sense used by theropods to hunt their prey?
Sight
What feature on the neck allowed rapid and precise head movement?
Highly mobile neck joint
What is a possible use of the extra digit on a theropod’s hand?
It’s possible it acted like a thumb and allowed them to grasp things.
True or False: All theropods were quadrapeds.
FALSE!
They were all obligate bipeds
Why was the pelvis of theropods large?
To allow for large muscle attachments in the legs
What is the similarity between a bird tail and a theropod tail?
There were flexible vertebrae near the base of the tail, but as you move towards the posterior, the bones lose their functionality and serve mostly as a balance.
What feature of theropods eventually aided their descendants (birds) to fly?
Hollow bones. It originated in theropods to make locomotion easier.
What are the three groups of theropods?
Primitive taxa, ceratosaurs, and tetanurans
What was the first relatively large theropod predator in the Jurassic that marked the beginning of theropod dominance?
Dilophosaurus
What are the evolutionary novelties of Ceratosaurs?
6 or more sacral vertebrae, very deep coracoids, weak forelimbs, and weak/perhaps nonfunctional hands.
What was the first non-carnivorous theropod?
Limusaurus
True or False: All theropods were carnivores
FALSE. There were even herbivorous theropods
What does Tetanurae mean?
Fused tails
What is the difference between tetenurans and ceratosaurs/other theropods?
They were much more bird-like
What are the three biggest groups of Tetanuran theropods?
Megolosaurs, Carnosaurs, Coelurosaurs.
The Carnosaurs and Coelurosaurs are united in a group called Avetheropoda because that’s the group that birds came from.
What characteristics did megolosaurs have?
long skulls, elongated snouts, small or no crests on skull roof,
Who discovered Megolosaurus
William Buckland in 1824 (first dinosaur)
What was the largest theropod?
Spinosaurus
True or False: Spinosaurids were carnosaurs.
False! They were megolosaurs.
What were the evolutionary novelties of the avetheropods?
additional fenestra in their maxilla, complicated air sac chambers in their vertebrae (remember the latex duck), and a reduced fourth digit in the hand.
What were the most dominant group of theropods?
Carnosaurs
Most well-known Carnosaur?
Allosaurus
What were the most bird-like Tetanurans?
Coelurosaurs
Evolutionary novelties of Coelurosaurs
Largest brains, tridactyl hands with extra long second and third digits, narrow metatarsals, and boat-shaped chevron bones
What are protofeathers?
Primitive feathers, mainly used for insulation (don’t look like feathers, look almost like thin, wavy tentacles)
What are the three groups of Coelurosaurs?
Primitive, Tyrannosaurids, and Maniraptoriformes
What is the best example of a primitive coelurosaur?
Compsognathus
Evolutionary Novelties of Tyrannosaurids
Fused nasal bones, incisor-like premaxillary teeth, very slender third metacarpal
What is the function of the forelimbs of a tyrannosaurus rex?
It’s unclear. They’re basically useless when compared to the size and weight of the dinosaur. We know they couldn’t reach the mouth and they couldn’t lift the dinosaur up… .so they’re dumb.
There is SOME research that suggests the forelimbs could have been used for balance purposes or to clutch prey. mebbe
True or False: Tyrannosaurus Rex was one of the first predators to evolve in the theropod group?
FALSE! They were one of the last, they were also some of the last dinosaurs alive.
Evolutionary novelties of maniraptorformes
Even LARGER brains, skulls small relative to body size, increased number of smaller teeth
What are the two groups of maniraptoriformes?
Ornithomimosaurs and maniraptorans
What does ornithomimus mean?
Bird-mimic
What modern day birds do ornithomimosaurs look like?
Ostriches and Emus
Evolutionary novelties of ornithomimosaurs
Lightly built skull, large orbits, short snouts, lack of almost all teeth, and long neck.
What was the diet of a struthiomimus?
Probably omnivorous.
Evolutionary novelties of maniraptorans
Larger brains, large bony sternum, elongate forelimbs
Best known groups of maniraptorans?
Oviraptosaurs, deinonychosaurs,
Which theropod group is generally considered to consist entirely of herbivores?
Segnosaurs
Which of the following is NOT a tetanuran theropod?
Compsognathus
Szechuanosaurus
Dilophosaurus
Allosaurus
Megalosaurus
Dilophosaurus
The skeleton found in the gut region of a Compsognathus pertains to a…
lizard.
It was originally thought to be a cannibal, but now they aren’t sure.
True or False: The arctometatarsal metatarsus is a derived character diagnostic of Theropoda
False
Why is it difficult to prove theropod relationships?
Because most speciments are incomplete and there is a lot of diversity
Which clade is characterized by long, slender necks and generally toothless skulls?
Ornithomimids
