Vertebrate Origins Flashcards
What is systematics?
The study of biological diversity using phylogeny, the evolutionary relationship between groups of organisms
What is taxonomy?
The description, identification and classification of species
What is classification
The arrangement and hierarchy of taxa
What is a monophyletic group?
Groups of taxa that consist of a common ancestor plus all descendants
What is a paraphyletic group
A group that contains an ancestor but not all of its descendants
What is a polyphyletic group give an example
A group of organisms that do not all share the same ancestor (Indian river dolphin does not share same ancestor as other river dolphins)
What 2 infraphylums does vertebrata split into?
Agnatha - jawless fish
Gnathosomata - jawed vertebrates
What are the cyclostomata?
The living jawless dish (superclass)
Why are the Chondrichthyes
Cartilaginous fish
What are the Osteichthyes
Bony fishes
Common features of chordates
- bilateral symmetry
- notochord (dorsal rod of specialised nerves
- pharyngeal pouches - gill slits
How long ago did the chordates evolve/ how many species
540 May
52,000 species
What are the extant lower vertebrates?
Hagfishes Lampreys Cartilaginous fishes Ray finned fishes Love finned fishes Lungfishes Amphibians
Why are vertebrates a good model for studying evolution?
- monophyletic group
- free living
- basic anatomy and development in common
- diversity of form and function can be related to adaption and evolution
- vest studied eukaryotic group
- good fossil record
What are the extant higher vertebrates? (Amniotes)
- testudines - turtles etc.
- lepidosaura - snakes lizards etc.
- crocodilia - crocodiles etc.
- aves - birds
- mammalia
from where and when did amniotes arise?
From a tetrapods amphibian 370mya
What are the common features of vertebrates
- post anal tail
- vertebral column
- specialised sensory organs
- brain at anterior end or nerve cord
- closed loop circulatory system
- myomeres (muscle segments)
- have cranium
What are the 10 systems the organisms of vertebrates are organised into?
Skeletal Muscular Integumentary Digestive Respiratory Circulatory Excretory Immune Nervous Reproductive
When did the agnatha originate
500mya
What are the two extant groups of agnathans
Lampreys
Hagfish
Features of agnathans
- absence of paired fins
- seven or more paired gill pouches
- no identifiable stomach or appendages
- fertilisation and development are external
When did the Osteichthyes originate
410mya
How many species are there
25,000, 60% are marine
Characteristics of bony fish?
- scales
- gills
- cold blooded (apart from swordfish and tuna)
When did Chondrichthys appear and how many species?
420mya 1200 species (500 sharks, 600 rays and skates)
