Lecture 22 - Dinosaur Flashcards
When was the mass dinosaur extinction?
65 million years ago
What periods make up the Mesozoic era?
Triassic, Jurassic and Cretaceous
A bipedal dinosaur needed a long tail for:
Locomotion
What were dinosaurs?
Archosaurian diapsid reptiles
What posture did dinosaurs have?
Upright posture with limbs under the body
What are the three dinosaur groups?
Ornithiscia - Herbivores
Saurpods - Herbivores
Theropoda - Carnivores
What is the classic interpretation of dinosaur relationships?
Ornithischia within their own group with bird hip characteristics.
Saurischian ‘lizard hip’: which included sauropods and theropods
What is the modern interpretation of dinosaur relationships?
Ornithoscelida: Ornithischians and theropods
Sauropods by themselves
What separates dinosaurs from other reptiles regarding their posture?
Dinosaurs have an upright posture unlike other reptiles that have their legs on the side of their body
What are some different types of fossils?
Amber Feathers Skin impressions Skeleton Eggs Footprints Coprolites
What do fossilised footprints and trackways allow use to estimate about an animal?
Allow use to estimate the leg length (due to imprint left and distance between imprints), body width (distance between imprints), and speed (distance between imprints)
Obligate bipeds
Walked only on two legs, e.g., raptors
Facultative bipeds
Walked on hind legs as a juvenile, transferred to four legs when adult e.g., Hadrosaurs
Obligate quadrupeds
Stays on four legs for its entire lifetime e.g., sauropods
A recent study discovered that a Spinosaurus had adapted what for aquatic locomotion?
Spinosaurus has adapted a large fin-like tail for propulsion
How is the diet of dinosaurs determined?
Diet is inferred from the skulls and teeth
A study by our lord Alistair Evans found Spinosaurus’ teeth had…?
Fine ridges on the teeth which correlate with aquatic feeding
What were dinosaurs relationships with brain size?
They showed the general relationship between relative brian size and metabolic rate. Generally dinosaurs brain size was slightly larger than those of modern reptiles
Encephalisation quotient in dinosaurs
Showed a similar range in mammals as in dinosaurs
Do dinosaur bones have more similarities with reptiles or mammals?
They are more like mammals.
There is a higher proportion of remodelled secondary bone.
Bone remodelling may be due to great weight
Did dinosaurs have low (reptiles) or high growth rates (mammals)?
Dinosaurs have high growth rates
What does a dinosaur’s bone histology tell us about its relationship to reptiles and mammals?
A dinosaurs bone blood supply suggests more rapid metabolic processes than modern reptiles, more similar to modern mammals
Are dinosaurs Endotherms or Ectotherms?
they are neither, dinosaurs fall in their own area called Mesotherms, which is in between both
What is the evidence of group behaviour within dinosaurs?
Display structures Sexual dimorphism Allomorphic growth Mass-death assemblages Parental care and nesting behaviour Multiple trackways
What is some evidence supporting the Alvarez hypothesis (asteroid) in dinosaur extinction?
Iridium-rich time period
Faunal mass death
Fish contain spherules in gills
Exceptional preservation of plants, birds, fish, mammals and dinosaurs
What would have been the major consequences of an asteroid impact 65 million years ago?
Reduction of photosyntheis
The layering of rare elements
Climate change
Extinctions
