Birds, Bird Evolution Flashcards
What markings were found on rocks in the limestone quarry?
Feather markings
These markings indicate the presence of prehistoric birds.
How old were the rocks in the limestone quarry?
150 million years old
This dating places them in the dinosaur period.
What significant fossil was discovered a year later at the same site as the limestone quarry?
Archaeopteryx
This fossil exhibits both avian and reptilian features.
List the avian features of Archaeopteryx.
- Wings
- Feathers
- Fused clavicle (furcula)
- Opposable hallux (big toe)
These features indicate its bird-like characteristics.
List the reptilian features of Archaeopteryx.
- Claws
- Teeth
- Bony tail
These features highlight its evolutionary link to dinosaurs.
What is the hypothesized phylogeny of birds from dinosaurs?
Birds evolved from theropods around 150 million years ago
This separation led to the ancestors of extant birds.
What were the early purposes of feathers?
- Insulation
- Camouflage
- Display
Flight evolved much later than feathers.
What is one benefit of flight?
Effective locomotion
Flight allows for movement over long distances.
Fill in the blank: Migration between seasonal feeding and breeding areas is a benefit of _______.
[flight]
What are two food sources that birds can access due to flight?
- Flying insects
- Fruit & flowers on trees
This increased range of food sources is crucial for survival.
What does adaptive radiation refer to?
Rapid diversification of species
It often occurs in response to ecological opportunities.
What is the cursorial model of wing evolution?
Flight evolved in running bipeds through a series of short jumps
This model suggests that wings were used for thrust and stability.
What are the negatives of the cursorial model?
- Implausible energetics
- No extant species uses wings to run faster
These points challenge the validity of this model.
How does the arboreal model explain the evolution of flight?
Flight evolved from gliding down trees
This model emphasizes the role of wings for balance.
What is a key observation related to the ontogenetic transitional wing hypothesis?
Ground-dwelling birds use wings to help run up inclines
This behavior has been observed in young birds incapable of flight.
List three adaptations to facilitate flight.
- Efficient wing & feather design
- Skeletal & muscular modifications
- Weight reduction
These adaptations are crucial for avian flight efficiency.
What are the three solutions to flight in convergent evolution?
- Common constraints (size, wing structure)
- Different solutions (supporting bones, muscle arrangements)
- Different directions (arboreal, cursorial, cliff jumping)
These factors illustrate the diversity of flight adaptations across species.
Define endothermy.
Maintenance of a high and stable body temperature by metabolic heat production
This adaptation allows birds to thrive in various environments.
What is shivering thermogenesis?
A mechanism for heat production in some insects and birds
It involves muscular activity to generate heat.
What are the characteristics of red muscle?
- Good blood supply
- Many mitochondria
- Much myoglobin
- Aerobic
- Sustained output
Red muscle predominates in endothermic animals.
What are the disadvantages of endothermy?
- Very expensive
- Need to eat more than ectotherms
- Can lose weight quickly
- Issues in food-scarce environments
- Detection by predators
These factors can impact survival.
How many bird species are there, and how many orders do they belong to?
10,000 bird species across 38 orders
This diversity is categorized under Class Aves.
What defines the subclass Neornithes?
It includes modern birds, with 3 flightless orders
These are believed to have evolved from flying ancestors.
What is an example of an evolutionary innovation that drives adaptive radiation?
Flight
Innovations like this can lead to rapid diversification.
