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Questions and Answers
What is a distinguishing feature of Oryctodromeus?
What is a distinguishing feature of Oryctodromeus?
- It had a long neck for reaching high vegetation.
- It was primarily a carnivorous species.
- It is known for its swimming abilities.
- It was the first dinosaur to show burrowing and denning behavior. (correct)
Why is the systematics of basal ornithopods considered volatile?
Why is the systematics of basal ornithopods considered volatile?
- Many species are well-preserved and abundant.
- Taxa are often known only from complete skeletons.
- There are no fossil records available from this period.
- Fragmentary specimens can closely resemble one another. (correct)
What time period do Oryctodromeus and other ornithopods generally belong to?
What time period do Oryctodromeus and other ornithopods generally belong to?
- Triassic Period
- Jurassic Period
- Early to Late Cretaceous Period (correct)
- Paleocene Epoch
What can be inferred about Basal Iguanodontoidea and Hadrosauridae based on their classification?
What can be inferred about Basal Iguanodontoidea and Hadrosauridae based on their classification?
What is the significance of Burianosaurus augustai's discovery?
What is the significance of Burianosaurus augustai's discovery?
What is the significance of Yandusaurus in the context of Ornithopoda?
What is the significance of Yandusaurus in the context of Ornithopoda?
What distinguishes basal ornithopods from euornithopods?
What distinguishes basal ornithopods from euornithopods?
Which of the following statements is true about the size of ornithopods?
Which of the following statements is true about the size of ornithopods?
What evolutionary period is associated with the emergence of Ornithopoda?
What evolutionary period is associated with the emergence of Ornithopoda?
Which of the following taxa is classified as a basal ornithopod?
Which of the following taxa is classified as a basal ornithopod?
What is a defining feature of Lambeosaurinae hadrosaurids?
What is a defining feature of Lambeosaurinae hadrosaurids?
How many individual teeth can the dental battery of hadrosaurids contain?
How many individual teeth can the dental battery of hadrosaurids contain?
What distinguishes hadrosaurid teeth from those of other vertebrates?
What distinguishes hadrosaurid teeth from those of other vertebrates?
Which of the following features is NOT associated with hadrosaurids?
Which of the following features is NOT associated with hadrosaurids?
During which geological period did hadrosaurids exclusively exist?
During which geological period did hadrosaurids exclusively exist?
How do hadrosaurids achieve continuous grinding of food?
How do hadrosaurids achieve continuous grinding of food?
What is the function of replacement teeth in hadrosaurids?
What is the function of replacement teeth in hadrosaurids?
How does the complexity of hadrosaurid teeth compare to that of mammals?
How does the complexity of hadrosaurid teeth compare to that of mammals?
What characteristic is NOT associated with Iguanodontoidea?
What characteristic is NOT associated with Iguanodontoidea?
Which of the following statements about Tenontosaurus is true?
Which of the following statements about Tenontosaurus is true?
What is a distinguishing feature of Hadrosauridae?
What is a distinguishing feature of Hadrosauridae?
How long could Iguanodon grow?
How long could Iguanodon grow?
What ecological role did Hadrosauridae play in their environment?
What ecological role did Hadrosauridae play in their environment?
What evidence suggests social behavior among Iguanodon?
What evidence suggests social behavior among Iguanodon?
Which dinosaur is associated with having a toothless premaxilla?
Which dinosaur is associated with having a toothless premaxilla?
Deinonychus is suggested to have engaged in what kind of hunting behavior?
Deinonychus is suggested to have engaged in what kind of hunting behavior?
The term 'unguals' refers to which part of the Iguanodontia?
The term 'unguals' refers to which part of the Iguanodontia?
Which feature is unique to the Hadrosauridae family?
Which feature is unique to the Hadrosauridae family?
What describes the likely social behavior of hadrosaurs during the Late Cretaceous?
What describes the likely social behavior of hadrosaurs during the Late Cretaceous?
What type of evidence supports the idea of social behavior in hadrosaurs?
What type of evidence supports the idea of social behavior in hadrosaurs?
What is a significant characteristic of hadrosaur jaws?
What is a significant characteristic of hadrosaur jaws?
What does the evidence suggest about the breeding behavior of derived ornithopods like hadrosaurs?
What does the evidence suggest about the breeding behavior of derived ornithopods like hadrosaurs?
What is indicated by the presence of large subadult and adult-sized bones in hadrosaur bonebeds?
What is indicated by the presence of large subadult and adult-sized bones in hadrosaur bonebeds?
Which hadrosaur species is mentioned as having evidence of child-rearing behaviors?
Which hadrosaur species is mentioned as having evidence of child-rearing behaviors?
How many disarticulated elements have been found in some hadrosaur bonebeds?
How many disarticulated elements have been found in some hadrosaur bonebeds?
What type of biomechanical process was maximally efficient in hadrosaurs?
What type of biomechanical process was maximally efficient in hadrosaurs?
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Study Notes
Ornithopoda
- Oldest fossil: Yandusaurus (Middle Jurassic)
- Survived until the end of the Cretaceous
- Known from all continents
- Size range: 2 to 14 m in length
- Basal members: Agile bipeds
- Large derived forms: Mostly quadrupedal
- Basal ornithopods (non-euornithopods): 4 hoofed-toes for weight support
- Euornithopoda: 3 functional hoofed-toes
- Systematics of basal ornithopods and ornithischians is volatile due to fragmentary specimens and similar morphology
Basal Ornithopods
- Burianosaurus augustai: Cenomanian of the Czech Republic, known from one femur
Orodrominae
- Early to Late Cretaceous, NA & Asia
- Oryctodromeus: First dinosaur to show burrowing and denning behavior
- An adult and two juveniles found in a den
- Bipedal with forelimbs adapted for digging
Basal Iguanodontians
- Tenontosaurus: Common dinosaur in the Early Cretaceous of western NA
- 75% of Tenontosaurus localities contain Deinonychus remains, suggesting pack hunting
Iguanodontoidea
- Longer, broader snouts
- Larger size
- Thumb spike (digit I)
- Digit V opposable
- Digits II & III robust with large, rounded, weight-bearing unguals
Iguanodontoidea: Basal Iguanodontoideans
- Iguanodon: Early Cretaceous, Europe; adults up to 10 m, ~3 tons
- Named in 1825 by Gideon Mantell
- 38 skeletons from a Belgian Coal mine
- 15 individuals from a bonebed in Germany: Evidence for sociality
- Forelimbs ~75% the size of hindlimbs
Iguanodontoidea: Basal Iguanodontoideans
- Ouranosaurus: Early Cretaceous, Niger; ~8 m in length, ~4 tons
- Toothless premaxilla; one row of replacement teeth
- Small crest in front of the skull
- Tall neural spines
Hadrosauridae
- Cretaceous; globally distributed
- Larger size: > 14 m in length (Shantungosaurus)
- Bipedal and quadrupedal capability
- Dominant mode: Quadrupedal
- "Duck bill" is a flaring of the premaxilla and predentary covered by a keratin-covered beak (rhamphotheca)
- Evidence for gregariousness and herding behavior
Hadrosauridae
- Two major clades: Hadrosaurinae and Lambeosaurinae
- Up to 15 m in length; 2 m skulls
- Exclusively Late Cretaceous in age
Hadrosauridae: Hadrosaurinae
- "Solid-crested"
Hadrosauridae: Lambeosaurinae
- "Hollow-crested"
- Cranial crest formed by the nasal bone
- Tall, symmetrical lancelet tooth
- Dental battery with three or more teeth
Hadrosaurids vs. Basal Iguanodontia
- Further expansion of the snout ("duck bill")
- Increase in the number of tooth positions
- Grinding dental battery with a continuous grinding surface
- Teeth with greater structural complexity
Hadrosauridae: Dentition
- Up to 1400 diamond-shaped, tightly packed teeth
- 5 replacement teeth constantly pushing
Hadrosauridae: Dental Histology
- Each tooth is comprised of at least 6 different dental tissues
- More complex than teeth of mammals, including horses
- Sophisticated dental system
Hadrosauridae: Abundance
- Most abundant dinosaurs in the Late Cretaceous of NA
- Moved in large herds
- Efficient jaws maximized energy from plant resources
Hadrosauridae: Social Behaviour (Bonebeds)
- Monodominant hadrosaur bonebeds are known from NA and Asia
- Dozens of Edmontosaurus bonebeds from the L Campanian and Maastrichtian of Canada and the US
- Some preserved >10,000 disarticulated elements
- Large subadults and adult-sized bones dominate
- Evidence for social and/or herding behavior
Hadrosauridae: Reproduction
- Not much evidence from basal ornithopods
- Derived ornithopods (Hadrosauridae) show evidence of child-rearing and parental care (e.g., Maiasaura, Hypacrosaurus)
- Nesting sites reused for multiple generations
- Evidence for 1 and 2 year juvenile cohorts
Hadrosauridae: Reproduction (Hypacrosaurus)
- Hypacrosaurus Nesting Site at Devil's Coulee, AB
Hadrosauridae: Soft Tissue Preservation
- Edmontosaurus regalis (L. Cret)
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