Vertebrates Flashcards
Evidence for reconstructing vertebrate history (3)
- comparative anatomy
- development of extant taxa
- geologic context
Archaeopteryx lithographica
Late Jurassic, Germany
Shows soft tissue preservation of flight feathers
Acanthostega gunnari
Late devonian, Greenland
Series of traits that show early evolution of the ear complex, and transitions from aquatic to terrestrial environments
Index fossils
Forms of life that existed during limited geologic times and are used as guides to the age of the rocks they’re in
Fossil types (2)
Body- preserved remains, particles in sedimentary rock
Trace- evidence of of past behaviour, structures in sedimentary rocks
Taxon-based measures (4)
Taxon presence
Relative abundancescale
Genetic diversity
Millennium- scale baselines
Taxon free measures (8)
Biomass Diversity Trophic structure Ecological network Functional traits Gene flow Assessing species invasions
Adaptive radiation & how (4)
Rapid diversification usually in response to some form of change
- geographic colonisation
- new resources
- key innovations
- major extinctions
Taphonomy
Study of processes controlling preserv
Taphonomic bias
Some organisms or environments have a
Preservation potential
Relative likelihood that an organism will be preserved in the fo
Primary processes that contribute to how a fossil is found
Necrolysis
Biostr
Biostratinomy
Post decay transport and burial p
Bioturbation
Mixing up of skeleton eg t
Biological necrolytic and biostatinimic destructive agents
Predation/scavenging
Scattering
Biocenosis
Life assemblages
Reflects natural community (single event)
Thanatocenosis
Death assemblage
Derived from transport and winnowing processes
Generally incomplete representation of faunas/floras
Time averaged- over representation of high durability and high abundance
Lagerstätte
‘Storage place’ - environments of exceptional preservation
Konzentrat- Lagerstätten
Disarticulated accumulations, ‘bone beds’
Most common for marine invertebrates
Konservat-Lagerstätten
Articulated remains, often includes soft tissue preservation
Factors affecting biostratinomy
Depositional environment Body size (how far it can travel) Hydrodynamic qualities (flow in air and water)
Biogenic minerals
Formed by metabolic processes eg. Hydroxyapatite
Dissolve in water when buried
Disgenesis
Physical and/or chemical alteration after burial (temp < 250°C)
Compositional types: permineralization, replacement-exchange, recrystallization
Permineralization (diagenesis)
Filling of open spaces with sedimentary minerals
Formation of sedimentary SiO2
Replacement-exchange (diagenesis)
Biogenic minerals replaced with sedimentary minerals
Recrystallization (diagenesis)
Formation of minerals from precursors of see chemical formula
Typically calcium carbonate eg. Aragonite to calcite
Autochthonous assemblage
Assemblages with little or no transport or winnowing
Actively inhabited depositional environment
Allochthonous assemblage
Assemblages transported to depositional environment from separate environment of habitation
Phylogeny
Pattern of evolutionary relationships
Taxonomy
Naming system based on common ancestry, derived from phylogenetics, describes evolutionary relationships
Biological species concept
Population of at least potentially interbreeding individuals that is reproductively isolated from other such groups, and are able to produce fit offspring
Morphological species concept
Individuals United by common morphology that is distinct from other such groups and is presumed to correspond to a biological species.
Plesiomorphy
Primitive or basal character
Symplesiomorphy
Shared primitive or unspecialized character
Apomorphy
Derived or specialised character
Autoapomorphy
Derived character or an evolutionary novelty found in only one taxon
Synapomorphy
Shared derived character between taxa. Is a potential homology
Only informative character for inferring phylogenetics relationships
Homology
Any character in different or
Homoplasy
Convergent evolution
Acquisition of shared characters from different origins
Advantages of morphological characters
Primary data for majority of life
Provides historical information
Provides direct info about adaptation and development
Disadvantages of morphological characters
Phenotypic data approximated genetic evolution to an unknown degree
‘Character’ delineation is subjective- are characters real?
Weight of individual characters, likelihood of transformations unknown
Advantages of molecular data
Direct data of genetic evolution
Character delineation is more objective (still have to align sequences)
Likelihood of character transformations (transversions vs transitions) statistically predictable
Disadvantages of molecular data
Data absent for 99.9% of known life
Relationship to external environment unknown, adaptation not understood
Homoplasy in base pairs increases with divergence times and rates. Genes have deep time limits
Phylogenetic methods
Parsinomy (cladistics)
Maximum Likelihood
Bayesian Inference
Monophyly
Lineage of organisms that includes a common ancestor and all of its descendants
Paraphyly
Lineage that includes a common ancestor but not all of its descendants
Clade
defined by their most inclusive taxonomic composition
Diagnosed using derived characters (apomorphies) used to support topology at a node and diagnose the clade named at that node
Node-based clade
Subtending taxa, their common ancestor and all its descendants
Stem-based clade
All taxa more closely related to a defined taxon
Apomorphy-based clade
Clade named based on 1st occurrence of a particular morphology
