Taxonomy and Phylogeny Flashcards
What is taxonomy?
The classification of organisms
It is a hierarchal classification
What were the problems with phylogenetic analysis before modern technology?
Evolutionary relationships were not acheived through rigorous scientific analysis - it was often done through hunches
Both the presence and absence of characters were considered
The lines of descent assumed we could identify ancestors
Too much reliance on stratigraphic distribution of fossils
How does cladistic analysis work?
Create character matrix - only presence of characters (NOT absence)
Analyse character distribution using parsimony or Bayesian methods
Identify homologous/analegous characters and hence synapomorphies, synplesiomorphies, autapomorphies in order to eliminate homoplasy
Establish sister group rather than ancestor-descendent relationships
Accepts only monophyletic groups
How did Seeley classify dinosaurs?
A non-monophyletic group
They arose from either the saurischia or ornithischia
Are pterosaurs dinosaurs?
No, found to be a sister group
What distinguished the Ornithischia and the Saurischia?
Their hip shape
Ornithischia = bird-hipped
Saurischia = lizard-hipped
Give some features of the Stegosauria
Had spines/plates down the back and tail - spines were basal and then the plates evolved
From the middle Jurassic to early Cretaceous
12 species identified
Up to 9m long
300-1500kg
Slow, around 6-7km/hr
Back legs longer than front legs
Herbivores
Probably didnt have any natural enemies
Not very intelligent - brain size was 0.001% of body mass
Give some features of the Anklyosauria
Bony plates across head and back
Large lump at the end of the tail
Middle Jurassic to early Cretaceous
Around 30 species discovered
5-9m long
~3500kg (max size)
Slow movement - ~10km/hr
Back legs longer than the front
As defence could either swing tail or hunker down and curl in to protect the head (due to armoured plates)
Not intelligent - wouldnt have had many predators
Give some features of the Pachycephalosauria
Thickened skull - could be 22cm thick
Lived in herds
Headbutted as a display for females
Lived mainly in the Cretaceous
Around 16 species discovered
2-8m in length
450kg
Fast
Bipedal
Average brain size - need some intelligence when you are a social animal
Give some features of the Ceratopsia
Have horn and shield - originally for defence but probably adapted for display
Around 40 species discovered
1-9m long
25-7000kg
2-4km/hr (walking) and 30-35km/hr (charging)
Herbivorous - had a beak-like structure to nip off vegetation
Charged as a defence - like a rhino
Lived in herds
Average brain size
Give some features of the Euornithopoda
Herbivores
1-15m
Up to 23,000kg
Bipedal
Long back legs but short front arms - could go down on their arms
Long tail
Lived in herds
Medium to high intelligence
Speed varies on size
Give some features of the Hadrosauridae
Duck-like appearance on the front
Have elabroation of the skull - sexual dimorphism of the skull
Lived in herds
Herbivorous
Varied in size
Give some features of the sauropods
Around 150 species discovered
Lived during the Triassic
23,000kg - 75,000kg
60km/hr (smaller species) and 20-50km/hr (larger species)
Tail and neck extened out
40m snout to tail
6m shoulder and 15m to head
Small skull - had a tiny brain and teeth
Herbivores
More active than people thought
Could go up on their hindlegs
Small when hatch and took around 20 years to mature and then stopped growing - could live to at least 100
Basal forms were bipedal, they went down on 4 legs and increased in size
Give some features of the Theropods
Around 160 species discovered
T.Rex was the largest species
40-60km/hr (smaller species were faster than larger ones)
Bipedal
Small front arms
Elongated tail
Only dinosaurs that hunted
Very intelligent
Efficient hunters
