Lecture 19- Australian Birds I Flashcards
What are the topics we will discuss during this lecture?
• evolutionary history • diversity & species richness • diversity of breeding systems • communication & bird song • conservation
What is the shared evolutionary history of birds and dinosaurs?
-Shared ancestor between birds & dinosaurs: Dromaeosurid theropods - e.g. Velociraptor -therapod dinosaurs are the ancestors
What is the Archaeopteryx?
-oldest known fossil bird 147MY (Jurassic)
What are the characteristics of Archaeopteryx?
Theropod dinosaur with flight feathers
• “Missing link” between dinosaurs and birds
- 1.2 m lomng
- reptile characteristics: -have teeth unlike birds -had claws unlike modern birds
- avian characteristics: feathers, wings and airfoil wing -birds are closely related to crocodiles
Why did flight evolve in birds, what advantages does it confer?
•Air - unexploited habitat, gives them a big advantage •Abundance of prey (flying insects) •Escape from terrestrial predators •Allows wide and fast travel •Migration – access to year-round favourable climate and resources
What drove the evolution of flight?
1.Ground Up • Wings evolved from arms used to capture small prey • Wings evolved because bipedal animals were leaping into the air; large wings assisted leaping 2. Trees Down • Wings evolved from gliding ancestors who began to flap their gliding structures in order to produce thrust. 3. Sexual selection • Wings were used as sexual display structures; bigger wings were preferred by potential mates.
What are the Australian bird fossils like?
• birds make poor fossils - small delicate bones otherwise couldn’t fly • 110 MYA fossil feathers from Koonwarra, Vic • 30 MYA penguin fossils & dromornithid tracks • 20 MYA extensive fossils of wetland birds in Central Australia
What is the most likely explanation for what drove the flight evolution?
Ground Up • Wings evolved from arms used to capture small prey • Wings evolved because bipedal animals were leaping into the air; large wings assisted leaping
What are the characteristics of Dromornis stirtoni?
-aka “Stirton’s Thunder bird or the Giant Demon Duck of Doom • ‘Mihirung paringmal’ (giant bird) • Central Australia - 15 mya • Flightless, weight 500+ kg, 3m tall • Related to geese -largest birds ever, probably
What are the characteristics of Genyornis?
-present in Australia until approx 50,000 years ago. Rapid extinction due to climate change??
What are the 5 characteristics that define birds?
- • Feathers and wings (but not all can fly)
- • Very light, very strong skeleton, bones hollow
- • Beak (no teeth= so that is why not so common to have fossils of birds)
- • Lay hard-shelled eggs
- Endothermic
What is the classification of modern birds?
-Class: Aves - Order Passeriformies (passerines) = “perching birds”/song birds. Contains approx 1⁄2 worlds sp. Most diverse & widespread gp. & occurs in Australia - non-passerines 25 other Orders of birds (18 in Australia)
What is the diversity of bird worldwide?
-class: aves • Approximately 10,000 living species (more species than any other vertebrate group except fishes) • From 1.8g to 160 kg • Occur in all habitats • Highly social: interesting behaviour
How many bird species are there in Australia?
-800+ -large morphological diversity 8g (Weebill) to 85kg (cassowary)
What are the five broad categories of Australian birdsM
- Long-established non-passerines of Gondwanan origin
- Australasian passerines (perching/song birds) descended from Corvid family
- Recent passerine colonists from Eurasia
- Introduced species
- Worldwide groups
What are the characteristics of gondwanan non-passerines a) ratites?
- emu & cassowary : flightless, bulky
- the world distribution is gondawan
