Lecture 14: Theropoda

Question 1

The late triassic

Answer 1

Origin and early diversification of theropods, not the undisputed top predators around; coexisted with large land-dwelling carnivorous archosaurs

Question 2

The early jurassic

Answer 2

Theropods thrive in post triassic recovery, first large theropods are top predators

Question 3

The middle jurassic

Answer 3

Major radiation of new theropod groups, complete replacement of earlier models. Record consists of mostly medium to large, predatory forms

Question 4

The late jurassic

Answer 4

great diversity of size and form, giant slasher predators, early experiments in toothlessness and herbivory, tiny theropods with wings (including first birds), oldest fossil feathers, oldest fossil theropod eggs

Question 5

The early cretaceous (145-100 mya)

Answer 5

continued diversification of theropods

Question 6

Jurassic-cretaceous transition

Answer 6

Scarce terrestial record from earliest early cretaceous, ceratosauria worldwide in jurassic; absent from NA and asia in cretaceous, loss of some megalosauroid and allosauroid families, but more derived members of these groups are succesful, major increases in coelursaur and bird diversity

Question 7

Carcharodontosauria

Answer 7

Derived allosauroids, widespread in EK, acrocanthosaurus top predator in NA

Question 8

Spinosauridae

Answer 8

Derived megalosauroids, widespread in early cretaceous. Big hooked thumb claws; jaws and teeth specialized for catching fish (piscivory), sensitive snout for detecting prey underwater, and amazing convergence with pike conger eels

Question 9

Cretaceous coelurosaur diversity

Answer 9

Diverse diets and body types, relatively bigger brains than other theropods. Jehol Biota in northeastern china, approx. 125 mya- very diverse assemblage of feathered dinosaurs

Question 10

Sinosauropteryx

Answer 10

First “feathered dinosaur” discovered 1996. Showed that origin of feathers was unrelated to origin of flight

Question 11

Caudipteryx

Answer 11

Early oviraptorosaur from the jehol biota, secondarily flightless?

Question 12

deinonychosaurs

Answer 12

The sickle clawed raptors, some jurassic maniraptorans may belong, but small and difficult to distinguish from early birds. Most popular species are cretaceous

Question 13

Microraptor

Answer 13

Four winged dinosaur:did it fly/glide? new studies show plumage was iridescent

Question 14

Deinonychus and utahraptor

Answer 14

Mid sized north american Ek predators, known from multi individual assemblages: living and hunting in packs?

Question 15

Cretaceous birds

Answer 15

Diverse spectrum of fairly primitive to near-modern early cretaceous birds. Modern avian traits such as tooth reduction/loss fused and reduced hand, perching foot, pygostyle. Refinement of powered flight stroke

Question 16

The late cretaceous (100-66 mya)

Answer 16

Divided world of the last non-avian theropods

Question 17

Mid cretaceous giants

Answer 17

Biggest known theropods are carcharodontosaurids and spinosaurids from the early late cretaceous of south america and africa.

Question 18

Gigantosaurus

Answer 18

Giant carcharodontosaurid from Patagonia, 13m long (skull about 1.8m) and 7000 kg.

Question 19

Spinosaurus

Answer 19

Giant spinosaurid from north africa, most aquatially adapted non-avian theropod

Question 20

other gondwanan theropods

Answer 20

large and small abelisauroids (derived cerotosaurs) Megaraptorids (tetanurans of uncertain affinities)

Question 21

Abelisauroids (ceratosauria)

Answer 21

Diverse large and small predators, strange procumbent teeth in masiakasaurus: for catching small prey?
South america, africa, madagascar, india france. Deep ornamented skulls, very short arms and hands (shorter arms than T rex)

Question 22

Unenlagiines

Answer 22

small to large, close relatives of birds

Question 23

Asia and North america

Answer 23

Last asian carcharodontosaurids and spinosaurids about 92-85 mya. Last 20 million years of the cretaceous: all known theropods in Asia and North America are coelurosaurs. Paralllel acquisitions among cursorial groups of an arctometatarsalian foot with a pinched metatarsal

Question 24

Small theropods

Answer 24

good skeletons are rare in north america. Because of a taphonomic problem: small delicate skeletons easily destroyed before burial, well represented by isolated teeth and certain isolated bones. Did they hunt small prey?

Question 25

Ornithiomimosaurs

Answer 25

Late cretaceous species are toothless, ostrich like body plan. Among the fastest dinosaurs. Previously unrecognized diversity in North America

Question 26

Oviraptosaurs

Answer 26

Short, deep beaks. Some with crested skulls, large eggs produced in pairs, bird like brooding posture on nests

Question 27

Non predator theropod giants

Answer 27

Late cretaceous of Asia, size comparable to tyrannosaurids, deinocheirus arms 2.4 m long; skull and rest of body recently only described

Question 28

Tyrannosauridae

Answer 28

Last radiation of giant carnivorous dinosaurs, 80-65mya. Asia and western North america, related tyrannosauroids in eastern NA

Question 29

Tyrannosaurus rex

Answer 29

Over 12 m long, about 6000 kg. Very well studied theropod, only giant carnivorous dinosaur in North America at the end of the cretaceous. They hunted hadrosaurs and ceratopsians, southern range overlapped with sauropods

Question 30

Tyrannosaur Teeth

Answer 30

Front teeth are smaller and D shaped in section, large thick maxillary and dentary teeth, strongest bite force of any terrestial carnivores, tooth markes bones

Question 31

Tyrannosaur skulls

Answer 31

Back of skull massively expanded in t rex (less in other tyrannosaurids

Question 32

Tyrannosaur arms

Answer 32

Short only 2 digits, powerfully muscled, probably not useless

Question 33

Where was the first tyrannosaurid trackway discovered?

Answer 33

BC, 2014. shows 3 individuals walking together in the same direction

Question 34

Does small skull represent Nanotyrannys or a juvenille t rex?

Answer 34

Juvenille T rex appears most likely. Low diversity of large predators in the latest late cretaceous NA, compared to late jurassic

Question 35

The fate of theropods

Answer 35

Massive loss of diversity at end cretaceous mass extinction, all non avian theropods, plus many bird groups also became extinct

Question 36

Survival of birds

Answer 36

Beaks and seed eating may have been key to survival. Veagviidae- late creatceous to paleogene diving anserifromes (same order as modern ducks and geese) Distribution around southern oceans, implies at least a limited radiation of other modern bird groups before the end cretaceous extinction