final Flashcards
What type of animals were in parts of Gondwana?
small predators and herbivores that were often crocodyliformes
What were the two major landmasses during the Late Jurassic?
Laurasia and Gondwana
What are the two types of causes of events?
Ultimate and direct
When was the major mass extinction at the end of the Mesozoic?
65 million years ago
What percentage of the existing species disappeared in the Cretaceous-Paleogene mass extinction?
30%-70% over span of thousands to millions of years
What was the ultimate and direct cause of the mass extinction?
Ultimate: maybe earthquake, rising sea level, or meteor
Direct: Habitat loss
What were the massive eruptions in India at the end of the Cretaceous period called?
Deccan Traps
Where is the massive crater at?
Yucatan Peninsula
When did many mammal clades arise?
During the Cretaceous
What was the most important event of the Cenozoic?
The Grand Coupure, the change from hothouse to icehouse
Cenozoic saw the emergence of what?
Grasslands
What was the “Ice Age”?
series of glacial periods over the past 2 to 2.5 million years
What were some important changes by the middle of the Cretaceous?
The appearance of angiosperms (flowering plants), the breakup of Laurasia and Gondwana
In the Late Permian, where were all continents conjoined as pangea?
Mostly in the southern hemisphere
What caused the mass extinction at the end of the Permian?
it is unclear, but perhaps changes in seawater climate and chemistry
In the early part of the Late Triassic, what type of animals were no longer present?
large cynodonts
By the end of the Triassic, what animals were no longer present?
dicynodonts and large pseudosuchians
What were the results of Pangea’s northward shift?
the expansion of tropical zones and the expansion of arid zones
How was wide dispersal allowed in the Late Triassic?
the continents were still connected
Sauropods, stegosaurs, ankylosaurs, ornithopods, and marginocephalians were what type of eaters?
herbivores
allosauroids, megalosauroids, ceratosaurs, and coelurosaurs were what type of eaters?
predators
What continents made up Laurasia?
N. America, most of Eurasia
What places were part of Gondwana?
S. America, Africa, South Asia, Madagascar, Australia, and Antartica
What is the general rule for Cretaceous land vertebrates?
Laurasia was dominated by dispersal, Gondwana was dominated by vicariance
Aves had a pneumatic hole where?
on the humerus
Why do Aves seem to appear at different times based on fossils and the DNA record?
The fossil record is incomplete and biased, and molecular dates are imprecise
On pterosaurs, what digit(s) supported the wings?
Only the 4th digit, which was elongated
What is the notarium?
fused dorsal neural spines
What are the synapomorphies for crocodyliformes?
skull table (skull flat behind orbits) and secondary palate
How can you tell the difference between a croc and an alligator?
Alligators have overbites, crocs have interweaving teeth
What are the general modes of locomotion in secondarily aquatic amniotes?
tail-driven (long tail, short humerus/femur) or flipper-driven (short tail, long humerus/femur)
How did secondarily aquatic amniotes modify their sensory system?
they had large eyes and well-developed ears
Where was the nares shifted in secondarily aquatic amniotes?
toward the top of the head
What are the two birth strategies in secondarily aquatic amniotes?
live birth or laying eggs on land
What causes a downwardly bent tail?
the shape of the caudal vertebrae
How were synapsids able to process microbes?
They had broad, barrel shaped torsos that allowed a big gut size
Why did therapsids have more of an upright posture?
the femoral head was inturned
What is important about cynodontian vertebrae?
The dorsal vertebrae were separated into lumbar and thoracic regions (thoracic have ribs), and therefore they had diaphragms
What is important about mammalia teeth?
They have true molars and premolars and only two sets of teeth
In humans, what does the postdentary bone move from the jaw to?
the ear
What are monotremes?
egg-laying mammals
What 3 structures never appeared in marsupials?
wings, hooves, and flippers (they need grasping hands)
Who realized the connection between dinosaurs and birds?
John Ostrom
What are some traits that arose independently in mammals and birds?
upright posture, the ability to breathe and walk at the same time, external body coverings, warm-blooded
When do crocodylians reach sexual maturity?
Before terminal size
When do most mammals and birds reach sexual maturity?
at or after terminal size
When do animals with seasonal growth tend to grow fastest?
during the warm season
If the source of body heat is external, animals are:
ectothermic
If the source of body heat is internal, animals are
endothermic
If body temperature is constant, animals are:
homeothermic
If body temperature is variable, animals are:
poikilothermic
If an animal has a high metabolic rate, it is:
tachymetabolic
If an animal has a low metabolic rate, it is:
bradymetabolic
How can an animal be ectothermic and a homeotherm?
By having a large body size and behavioral control
How can some animals be endotherms without mitochondria?
by having lots of muscular activity
What are some pros of being an endotherm?
having greater endurance and greater cold tolerance
What is biogeography?
the study of geographic distribution of organisms
What is vicariance?
the division of a population by a geographical barrier
What is dispersal?
the extension of a population across a geographic barrier
What are the 3 basic types of plate boundaries?
divergent, convergent, and translational
When is dispersal preferred over vicariance?
When geographic and organismal phylogenies don’t match
