1 Animal Diversity Flashcards
What are the largest to smallest units of time in Earth’s history?
Eon > Era > Period > Epoch
In which eon did life originate, and approximately when?
Archaean eon, ~3.5 billion years ago
What major development occurred during the Ediacaran period (635-541 Ma)
Evolution of multicellular invertebrate animals
What was the Cambrian radiation?
A sudden appearance of many new animal body plans, possibly due to increased atmospheric oxygen
What evidence supports a meteor impact causing the end-Mesozoic extinction?
A layer of clay with iridium (common in meteorites) found in global sediments
What major event occurred at the end of the Paleozoic era?
The greatest mass extinction (~90% of marine species, ~70% of land vertebrates)
What were the dominant land animals in the Triassic period?
Therapsids (reptiles), some of which evolved into mammals
What occurred during the Paleocene epoch?
Radiation of small, primitive mammals
When did humans evolve?
Holocene epoch
What is systematics?
he science of diversity and evolutionary relationships of organisms
What is the binomial naming system, and who developed it?
A system assigning each species a two-part name (Genus + Specific epithet), developed by Carolus Linnaeus
What is a phylogenetic tree?
A graphical representation of hypothesized evolutionary relationships
What is the difference between monophyletic, paraphyletic, and polyphyletic groups?
Monophyletic: Includes a common ancestor and all its descendants
Paraphyletic: Includes a common ancestor but not all descendants
Polyphyletic: Grouped together but do not share a common ancestor
What is a defining feature of all animals?
Multicellular eukaryotic organisms without cell walls, with collagen for support
What is cephalization, and why is it important?
Development of a head with sensory structures; it aids in movement and response to stimuli
What challenges do freshwater animals face compared to marine animals?
Hypotonicity, temperature changes, turbidity, and nutrient limitations
What adaptations help animals live on land?
Internal lungs, protective skin, internal fertilization, skeletal support
What are the two main types of body symmetry in animals?
Radial symmetry: Body arranged around a central axis (e.g., jellyfish)
Bilateral symmetry: Left and right halves mirror each other (e.g., humans)
What role do Hox genes play in animal development?
They specify the anterior-posterior axis during development and influence body plan evolution
