Pre christmas Flashcards
What is the biological species concept and what are its associated problems?
Its a definition of a species:
A group of actually or
potentially breeding natural
populations that are
reproductively isolated from
other groups
Problems:
* Not applicable to asexually reproducing organisms
* Cant tell if fossils could reproduce
* Borderline cases like crows where they overlap, is difficult to establish if produce fertile offspring or not
What is the phenetic species concept, and what are the problems associated it ?
Problems:
* Genotypes dont produce fixed phenotypes like in the case of Ecophenotypes
* Cryptic species and sibling species
* Some fossils look the same
What is cladistics?
A method of hypothosising the reationships between organisms based on uniquely shared characteristics or traits
What is paraphyletic and polyphyletic?
Paraphyletic:
(of a group of organisms) descended from a common evolutionary ancestor or ancestral group, but not including all the descendant groups.
Polyphyletic:
(of a group of organisms) derived from more than one common evolutionary ancestor or ancestral group and therefore not suitable for placing in the same taxon:
Define
Synapomorphy
Plesiomorphy
Synapomorphy: A shared, derived character state. This is an apomorphy that two taxa share and that is assumed to have been present in the common ancestor of those two taxa. An example would be feathers in birds. All birds have feathers
Plesiomorphy: An ancestral character state. This is any trait that was inherited from the ancestor of a group. For example, reptiles are exothermic, they do not maintain a constant internal body temperature. They have this characteristic because the ancestor of all reptiles was exothermic. This differs from a synapomorphy because some descendants of the first reptiles are not exothermic (birds are endothermic). In other words, this trait is ancestral, but is shared by some, but not all, of that ancestors; descendants.
Analogous vs homologous
Homo - same evolution orgin trait
anal - diff, but looks similar
Exaption
When a feature has been coopted to serve a new function
What are the metazoa and what are the 5 clades within this grouping?
- Kingdom consisting of Animalia
- A monophyletic group
Common characteristics:
* Multicellular
* Specialisation of tissues
* Motility
* Heterotrophy
Sexual reproduction
Describe Porifera
Part of the Metazoan kingdom
AKA Sponges
Anatomy
* Choanocytes line the cavities inside
* Choanocytes generate water flow and filter feed
Microscopic spicules are part of the structure of sponges
Describe Ctenophore
- Ctenophora is the sister group to other animals according to phylogenomic studies
- Motility from cilia
- Radial symmetry
- Diploblastic, both mouth and anus, through gut
- Combs of Cilia called Ctenes
Describe Cnidaria
- Part of Metazoan Clade
- Anthozoa and Medusozoa
- Diverse, jelly fish anemones and corals
- Characterised by stinging cells called cnidocysts
- Radial symmetry
Cnideria all have a life cycle involving a sexual medusa stage, mobile planula larval stage and a sessile budding stage - They differ in which part of the life cycle forms the adult
Describe placozoa
- part of metazoan clade
What is long branch attraction?
- Long branch attraction (LBA) is a phenomenon in phylogenetic analyses when rapidly evolving lineages are inferred to be closely related, regardless of their true evolutionary relationships. The problem arises when the DNA of two (or more) lineages evolve rapidly.
- Due to site heterogeneity where bases mutate at different rates, the ones which mutate faster may then confuse genetic analysis by making two species look more similar
List as many of the findings from the burgess shale
Ctenophore
Porifera
Cnidaria
Annelida
Mollusc
Priapulida - Ottola (penis worm)
Oncychophora - Halluciniga (spines on back)
Arthropoda
Deuterostomia
What was the burgess shale?
After a long period of relative stasis in the ediacaren, a rapid diversification appeared in the fossil record. The burgess shale exemplified this. Characterised by ‘weird wonders’
- rapid sea cliff collapse
- low sulfur and high alkalinity
These have been found in the burgess shale. Recall some characteristics.
Ctenophore
Porifera
Cnidaria
Annelida
Mollusc
Priapulida - Ottola
Oncychophora - Halluciniga
Arthropoda
Deuterostomia
Annelida
- Worm like segmentation
- Bristles for motility
Mollusc
- Large foot and radula
- split into several classes including Bivalvia, Gastropoda, Cephalopoda.
Priapulida - Ottola
- Preserved burrows
- U shaped gut
Oncychophora - Halluciniga
- Lobed limbs and spikes
Arthropoda
- Trilobites, preservation of antanae and legs
- Waptia, advanced compound eyes and legs
Deuterostomia
- Anus before mouth development
- Potential for hemichordates and Ecinoderms
- Hemichordates: triploblastic , enterocoelomate and bilaterally symmetrical marine deuterostome animals
- Echinoderms: most asexual and most 5 point radial symmetry
Deuterostomia: Metaspriggina
* Paired eyes
* Msucles on back
* Gill arches
* Chordate affinity
* A vertebrate! Closest cambrian relative
* Usefull for dispalying evolutionary points
Differentiate between stem and crown group
Crown group is a monophyletic group containing the living species down to their last common ancestor
Stem group is the last common ancester and its descendants excluding those alive today
What was the burgess shale?
After a long period of relative stasis in the ediacaren, a rapid diversification appeared in the fossil record. The burgess shale exemplified this. Characterised by ‘weird wonders’
What was the burgess shale?
After a long period of relative stasis in the ediacaren, a rapid diversification appeared in the fossil record. The burgess shale exemplified this. Characterised by ‘weird wonders’
What are the lophotrochozoa?
A very diverse clade of protosome animals within the spirilia.
What are the lophophore and trochophore?
Trochophore
* Larval stage for many of the lophotrochozoan clade.
* Characterised by bands of cillia and testicles for motilitity and feeding.
Lophophore
* Feeding apparatus that extends out
* used by many of the lophotrochozoans
What are the Bryozoa?
The moss animals
Phyla of lophotrochozoa
* Resemble aquatic plants, some individuals called Zoids for feeding, some for defence, division of labour, connected by a web of tissue
https://www.digitalatlasofancientlife.org/learn/bryozoa/
What are Entoprocta?
Superficially similar to bryozoa (ectoprocta). Lophotrochoza.
- Colonial
- Feeding crown not technically lophophore
Goblet animals
What higher phyla are the cycliophora apart of?
These are the ones which live in the mouth of a lobster.
Lophotrochozoa
What are the Gnathifera?
Rotifera: Thorny-headed worms, live in soil, spin their mouth parts
Micrognathizoa: Jaw animals, complex jaw, lay eggs
Gnathostomulida: Jaw Worms, eggs burst out their body
What phyla are the platyhelminthes in?
Lophotrochozoa
- contain flatworms, flukes and tapeworms
- Regenerative, some parasitic
- Bilateral
What are the Brachiopoda
- Bivalve appearance but lophophore inside
Lots in the palaeozoic
Lophotrochozoa
What are the Phoroniada (horseshoe worms)
Pretty sure the things that dissapear when you click.
* Phoronida - Have larvae - Bore into substrate - Filterfeed Horseshoe worms
What are the nemertae?
Lophotrochoza ribbon worms
Who are the freakin annelids am right!?
- Segmented
- Repeated segments of the body with ITS own organs and function
- Important ecological functions
Contain:
- Polychaetes, have bristles, diverse, predators to filter-feeders
- Clitellates, leeches, earthworms
What phyla do the mollusca belong to?
Lophotrochoza
- Diverse inside, giant squid, very small things
- Herbiverous,
- Emerged in mid cambrian
- Mainly marine, 23% all described marine organisms
Contain:
- gastropods
- cephlapods
What is the ecological importance of the annelids?
- Aeration
- Fertilisation
- Drainage
- Prevents compaction
What are the subphyla of the arthropods?
- Trilobites
- Chelicerates
- Mandibulates
What orders make up the Sub phyla chelicerata?
Contains orders:
- Meristomate
- Arachnida
-pycnigoda
What are Arthropoda characteristics?
- Segmented
- Jointed apendages
- Open circulatory system
- Moulting exoskelton
- Cephalized
Often sexually dimorphic
Who are the merostomata?
A class of Chelicerate containing:
The sea scorpions (Eurypterida)
- predatory
- known for gigantism, linked to the rising sea levels
Horseshoe crabs (Xiphosurida)
- Hemocyanin in blood
- compound eyes
Who are the Pycnognida?
A class in the Chelicerata.
- Sea spiders
- Parental behaviour, father
predatory
Describe the phylogeny of Arachnida.
A Class belonging to the subphyla Chelicerata.
Contain Order:
- Trigonotarbida (extinct)
* Araneae
* Opiliones
* Solifugae
* Scorpions
* Theyliphonda
* Amblypygi
- Acari
Describe the Order Trignotarbida
Trigonotarbida (class Arachnida)
* One of first to go to land
* Small around 4mm
Found in rhiney chert
Describe the order Araneae
- Aranae (class Arachnida)
- All but one obligate predator
- Silk production
- 40,000 species
Describe the Order Opiliones
- Opiliones (class Arachnida)
- One body section ish
- Can loose a leg if attacked
- known as harvestmen spiders
predator
Chew their food
Describe the Order Scorpiones
- Scorpiones (class Arachnida)
- Dominate arid predatory environments
- Very slow metabolism
- Some species can survive a whole year without food
- Generalists
Parental care, maternal
Describe the Order Theylyphonida (whip Scorpiones)
Theylyphonida (class Arachnida)
* ‘Whip scorpioins’
* Produce vinegar like chemical defense
* Tropical areas
Carniverous
Describe the Order Amblypygi (tailless whip scorpions)
Amblypygi (class Arachnida)
* Tailess whip scorpions
* Tropical
* Up to 70 cm legspan
* No silk or venom
Describe the order Acari
Acari (class Arachnida)
* Over 50,000 described species
* Million in one litre of lead litter
Fusion of abdomen
Describe the class Pycnogonid
Known as the sea spiders
* Structure called a Chelifore for feeding
- Carry eggs in a suck under the trunk
What are the mandibulates?
A clade of arthropods
Comprises the subphyla Myriapoda (millipedes and others), Crustacea and Hexapoda (insects and others).
What are the class Diploda
Millipedes and such
- A class within the Myriapoda, within the mandibulates
- two sets of legs per body segment
- decomposers
- body section 7 is used to transfer spermatophores
Describe the class Chilopoda
A Class within the Mandibulates, myriapods
* Chilopoda (centipedes)
* One set of legs per body segment *Predators
* Venomous fangs in front legs
* parental care
Within which grouping are the sub phyla crustaceans apart of?
The Mandibulates, along side myriapods and hexapods.
Describe the morphology of crustaceans
- Head
- Thorax
- Abdomen
- Soft bodies with hard calciocarbonate exoskeleton, or kitonous exoskeleton
- Shed for growth
- Legs for walking, for swimming, for defense
- Multijointed/biramous appendage
- Two antenna
- Larval stage, not every group
- Compound eyes
Are Crustaceans monophyletic or paraphyletic?
Paraphyletic
* some crustaceans are more related to other clades than their own according to genetic analysis
Describe the Order Isopoda
Part of the Crustacean sub phyla
- Terrestrial isopods woodlice
- Need humid environments as no cuticular cover
- lots scavengers
- some abisilgigantism (deep sea)
- some parasites
Describe the order decapoda
- lobsters
- Crabs
- Cray fish shrimp
- crab shape evolved 5 times, is a flexible shape for colonising habitats
- Part of the Crustacean taxon
Who are the Cirripedia?
Barnacles
* part of the Crustacean sub phyla
* Planktonic larval stage, unique to crustaceans
Describe the echinoderms
They are deuterostomes
- 5 point radial symmetry, shown to be a specialisation due to their bilateral larval stage
- star fish, sea urchins, sea cucumbers etc
What is cephalisation?
Concentration of nerves and sensory organs at the anterior (like our head)
What is the blastula?
A hollow ball of cells produced during the development of an embryo. Develops in the gastrula via invagination.
* Ectoderm, external layers * Endoderm, internal layers like gut lining * Mesoderm, between layers
What is the difference between a diploblastic and a triploblastic embryo?
Triploblastic has a mesoderm
Goes onto produce:
* Cardiac muscle
* Skeletal muscles cells
* Tubule cells of kidneys
* Red blood cells
* Smooth muscle
What does the presence of a mesoderm in the ctenophores suggest about the evolution of mesoderm?
- Ctenophore have classic mesoderm
- Nerve tissues, circulatory structures and muscles characteristics of triploblastic body plan
- If ctenophore is branches off early in the phylogenetic tree,
Then there must be two origins of mesoderms or multiple losses of mesoderms + all associated structures
What gave rise to bilatarian mesoderm?
Cnidarians
* Classic diploblast body
* Traditionally Inside layers of cnidarian endoderm gave rise to bilaterian mesoderm/ectoderm
Actually comes from the pharyngal area
In triploblastic body plans, there are three different levels of organisation with respect to the presence/ lack of a coelom.
Define Coelum and state the three levels
What are the two main divisions of bilataria?
State their differences
Protostomia (mouth-first development)
1) mesoderm develops inside the embryo
2) Each cell is determined to be a section, removal of one blastomere cell = embryo death
3) Spiral cleavage of the blastomere (cells divide in a spiral fashion
4) Nerve chord Ventral to the gut (below)
Deuterostomia (anus first development)
1) mesoderm develops as an offshoot from the digestive tube ring of cells
2) each cell is indeterminate, the removal of one blastomere cell creates the start of a second embryo
3) Radial cleavage of blastomere (cells divide in a radial fashion)
4) Nerve chord dorsal to the gut (above)
What are the 3 universally common features of Bilatarians?
- Bilateral symmetry
- Cephalization
- Mesoderm
What are the four superphyla of bilataria?
4 superphyla:
* Ecdysozoa
* Spiralia
* Deuterostomia
* Xenaceolomorpha
Describe the Superphylum Ecdysozoa.
A superhyla of bilataria
* contains arthropods and allied phyla
Describe the superphylum Spiralia
Spiralia, a Superphyla of bilataria
- Mostly Lophotrochozoa, so have lophophore and trochophore
- Spiral cleavage
For example, Platyhelminthes
Name a good example of a deuterostome.
A gill worm; Hemichordate
Fun fact! Hemichordates share many characteristics with us, the chordates. like:
- Pharyngeal Gill Slits
- specification along the anterior-posterior axis
Describe the superphylum Xenacoelomorpha.
Xenacoelomorpha; a superphylum of bilataria
* Simple and weird:
* Acoela, flatworm type
* nemertodermatida, worms
* xenoturbella, sac like phylum
Try and place the phylogentic groupings in order.
Mollusca
Bilataria
Spiralia
Cephalopoda
and
Hexapoda
Ecdysozoa
Bilataria
Metazoa
Arthropoda
What classification is Hexapoda?
A Subphylum of the arthropoda.
Metazoa > Bilataria > Ecdysozoa > Arthropoda > Hexapoda
What is the grouping hexapod?
A subphylum of arthropoda
* contains class insecta
* but also a couple of non insect hexapoda
What has made insects a successful species?
- high speciation rates coupled
with low levels of extinction - high reproductive capacity
- brief average generation time
- large effective population
size - an amalgamation of traits
that work synergistically - Body plan very mailable/open to adaptations, allows occupation of many niches
- Exoskeleton - flight, defence, prevents dessication
- Herbivory - a link between this and speciation due to specialisation and co-evolution with the plants they feed on
What is Hemimatabulus? aka Exopterygota
Semi metamophosis
Species like nymphs that have slow growth but can metamorphosis in a radical change such as aquatic to land.
What is Holometabulus? Aka Endopterygota
Holometabolous - Full Metamorphosis
- Larval stage
- Exploit different/multiple niches depending on stage, reduces competition between life stages
- Pupa to fly
Why did the Palaeodictyopterida (insect family) go extinct at the end Permian extinction but no others?
Perhaps…
* these were very big
* Gigantism linked to
increased 02 levels, but
disappearance of
gigantism due to the arrival of
aerial predators
* if nymph was aquatic, the death of lots of marine life may have affected it as well
What are the 5 orders of insects?
- Cleopatera: hardered wing sheath i.e ladybird
- Mecoptera: i.e scorpion flies
- Odonata: Dragonflies and damselflies, predatory
- Hymenoptera: Bees and ants, Sometimes eusocial
- Diptera: Flies
What are the key features of chordates?
1) Notochord
2) Dorsal Nerve cord
3) Pharyngeal gill slits
4) endostyle/thyroid
What three groups make up the Chordata?
1) Vertebrata
2) Cephalochordata
3) Urochordata/tunicates
Describe three groups that make up the chordates:
1) Cephalochordates
2) Urochordata/tunicates
3) Vertebrata
Cephalochordate: Amphioxus
* Small filter feeding
Simple, archetypal chordate
Urochordates: Tunicates
- all filter feeders, diverse lifestyles
* Sea squirts, undergo metamorphosis from a mobile juvenile stage with all the key features, to a sessile form and digest their brain
* Salps, Larvaceans
Vertebrata
* Jawless and jawed
Brain, pair sensory structures, branchial arches and some sort of vertebral column
How did the traditional view and the genomic view differ on the relationship between Chordata, tunicates and cephalochordates?
Tunicates according to genomic studies are actually closer related to chordates than cephalochordates.
Differentiate between Chordates and vertebrates in terms of characteristics/anatomy.
Chordates:
* Dorsal nerve chord
* Nortochord
* V shaped myomeres
* Post anal tail
* Pharyngeal gill slits
* endostyle
Vertebrates
* Brain
* Paired sense organs
* Fewer gill slits
* Thyroid
* Liver
* Heart
W shaped myomeres
What is the neural crest?
The neural crest is a migratory population of multipotent cells that form around the developing vertebrate neural tube
- Gives rise to a variety of cell types and forms important vertebrate characters (e.g. teeth, heart, nerve etc.)
Describe the ecology and anatomy of jawless vertebrates Lampreys and Hagfish
Lampreys
* parasitic, round mouths, oral sucker
* 7 gill openings, single nostril
* Cartilages instead of bones
* Backbone type thing
* Juvenile lamprey, more like a chordate, lacks eyes and an oral sucker
* Adult more like a jawless vertebrate
Hagfish
* single nostril, lots of gill openings
* No backbone type
* Neural crest (key characteristic)
* scavenger deep sea
Name some key characteristics of Vertebrata
- Developed brain
- Paired sensory structures
- Branchial arches
- Some sort of vertebral column
Who are the Gnathostomata?
Jawed vertebrates
What are some of the key anatomical characteristics of jawed vertebrates (Gnathostomata)?
Who are the cyclostomes?
The Jawless vertebrates
What did genomics reveal about phlogeny of verebrates?
That jawless fish are actually unique, with lampreys and hagfish being monophyletic.
What are Pikai and metaspriggina and why do they help with vertebrate phylogeny?
Early potential Cambrian vertebrates.
Metaspriggina
* Paired eyes
* Notochord
* Muscle bands
* gill arches
Pikaia
* Interesting early chordate
* Notochord
How can we remove decay bias?
Some tissues decay before others, causing stem ward slippage where we think they are less specialised than they are due to decay of specialist features.
- we can help remove this bias by comparing to known data
Who were the stem gnathostomes?
Ostracoderms; Jawless armoured fish
Placoderms; jawed armoured fish
What do the anaspids, conodonts and the Sacabambaspis, Heterostracans and the Galeaspids, Osteostracans represent?
They are types of Ostracoderms; jawless armoured fish that represent the evolution/ step-wise acquisition of Gnathostomes in stem- gnathostomes.
Conodonts (cone teeth)
* Mineralised teeth
* soft-bodied
Anaspids (no shields)
* Mineralized dermoskeleton
* Armour plates made of bone
2) More heavily ossified
Sacabambaspis
* Heavy armoured
* Paired sensory - two nostrils
* Widespread in the ordovician
Heterostracans
* Diverse head sheild shapes
Single gill
3) More complex anatomy
Galeaspids
* Single nostrils, individual nasal nerves going to it
Osteostracans
* Paired fins
* Bony shells
* Cool anatomy of inner ear and brain
Still jawless
4) development of placoderms
Name some of the step-wise acquisitions/transitions along the gnathostome stem.
Bone
* Started on the outside
* Mineralised
* Cellular bone
* Endochondral bone replacing the cartilage
Teeth
* Outside in hypothesis
* Derived from dermoskeleton
* Migrating into the oral cavity
Paired appendages
* Paired fins
* Paired nasal
Who are the cartilaginous fishies?
Name some characteristics
Chondrichthyes
Typical jawed vertebrate plus some specialiszatoins
* Closed blood system
* Vertebral collumns
Cartilage skeleton
* Cartilage mineralization of vertebral column tho
Scales
* Teeth like placoid scales
* Teeth derived from it
* Hydrodynamic efficient
Internal fertiisation
* using graspers
Senses
* Detect changes in water pressure
* Ampullae of lorenzini - cells able to detect electricity, find prey
What is the other name for Chondrichthyes?
Cartilaginous fish
Describe the diversity of Chondrichthyes
Holocephalans: Ratfish 50 species
Elasmobranchs: Sharks and rays 500 species
Who are the Elasmobranchii?
Sharks and rays
Name the four clades within gnathostomata
Who are the Actinopterygii
Actinopterygii; ray-finned fish
What are the key characteristics of the ray finned fish (Actinopterygii)
Key characteristics;
* Fin rays; lepidotrichia
* Bony Endoskeletonrr
* Swim bladder
* Operculum
* Bony scales (different to placoid cartilage)
Who are the Sarcopterygii?
Sarcopterygii; Lobe finned fished
- these were adapted to moving towards a terrestrial environment
Distinguish between Sexual dimorphism and hermaphroditism.
Sexual dimorphism: the difference in form between individuals of different sex in the same species. For example, the male is larger than the female in some species
Hermaphroditism: having both male and female reproductive organs. Hermaphroditic plants—most flowering plants, or angiosperms—are called monoecious, or bisexual.
Define parthenogeneis
Parthenogenesis: eggs develop into an embryo without fertilisation by sperm
Distinguish between oviparity and ovuliparity
Oviparity: internal fertilisation, eggs develop externally
Ovuliparity: external fertilization, obvs eggs external too
Distinguish between viviparity and ovoviviparity.
Viviparity: internal development of nurtured embryos
Ovoviviparity: internal development using resources from the egg only
Distinguish between Euryhaline, Semelparity and Iteroparity
Euryhaline: tolerates a wide range of salinity
Semelparity: one mass breeding event
Iteropartiy: continuos breeding throughout life
Who are the Teleostei?
One of the three divisions of ray finned fish
- have had a whole genome duplication event
- modified mouth parts; mobile premaxilla for protrusion feeding
- modified tailfins; homocercal tail
Non-Anchomophs and the Acnhomorpha are the divisions of what group?
The teleostei
Non-acnhomorphs
* salmon, herring, carp, eel
acnhomorphs
* Large diversity
* Cod
* Dories
What are the differences in bouyancy control in Chondrichthyes and in Osteichthyes
Osteichthyes
* Swim bladder, precise motor control
Chondrichthyes
* Oily liver, cant control bouyancy as much
Whats the difference between disparity and diversity?
Disparity shows more like the range of spread, high range of forms, diversity is just diff number of species.
Is quantified using mophometrics
What were the key events in the tetrapod transition to land?
Key events in transition:
* Land motility
* Change way lungs work
* Structural support
* Mainting amount of water in body
What evidence was there that tetrapods have evolved from lobe finned fish?
What was important about the sarcopterygian lobe finned fish?
Is the common ancestor to all tetrapods
What were the common features of early tetrapod fish?
- loose scales
- internal nostrils
- fins better able to support weight
What major anatomical differences allowed amphibians to progress out the water?
- Elongation of snout
- Reduction in the number of skull bones
- Loss of bones that covered gills and throats
- Interlocking vertebrae
- Limbs of supporting body weight
- Properly developed limb gurdles such as the petral gurdle, and detachment of the head to create a neck
- Nostrils on top of head
- gill covering changes
- Notochord is pressurised soft tissue that acts as support in early vertebrates
- In adult, role is minimal
In later tetrapods is replaced by bone
When did early amphibians begin to take shape?
Devonian (390ma)
what were some contributing factors to the extinction of many amphibians lineages, during the triassic. (also linked to Triassic mass extinction)
Was a time of Radical environmental change
- big rise in CO2 Concentration
- Desserts expanded
- No glacial activity
What is a sterospondyl?
An aquatic extinct group of early amphibians. Not plausibly the ancestor due to a completely different lifestyle. Also anatomy was to weak and simple to support weight, suggesting they were entirely aquatic.
Why is the ancestory of modern amphibians unknown?
Theres a gap in the fossil record where all other lineages die off and no linking fossil. Fossils were difficult to come by due to:
* Reduced skeleton
* Burrowing species
* Soft body parts
* Fertile environment
This coincided with the triassic extinction and was a time of radical environmental change:
* big rise in CO2 Concentration
* Desserts expanded
* No glacial activity
What evidence is there for modern amphibians to be a monophyletic group?
Pedicellate teeth
All have this tooth structure, unlikely to have convergently evolved, therefore suggesting monophyletic origin.
What is neotonic?
Neoteny also called juvenilization, is the delaying or slowing of the physiological, or somatic, development of an organism, typically an animal.
How do salamanders vary from other amphibians?
Have aquatic larvae, terrestrial adults and neoteny.
They are expected to be a monophyletic based on skull morphology.
What is romers gap?
A period of limited fossils linking ancestral amphibians to modern ambibians.
Who were the anapsids?
a clade of terrestrial vertebrates, which includes all of the descendants of the last common ancestor of the reptiles (including dinosaurs and birds) and mammals, is one of the most successful group of animals on our planet.
What 4 groupings made up the reptiles? According to what anatomical features?
synapsida
Euryapsida
anapsida
diapsida
When did reptilia orignate?
Carboniferous
Who was hylonomus and what was significant about it?
- was the earliest garunteed reptile and first known to be fully adapted for life on land
Describe the Ichthyosaurs
Ichthyosaurs
* Reptile
* Convergent evolution with fish/mammals
* Overtime reduction in size of flippers, propulsion begins to be dominated by tail
* Evolved from unknown land reptiles
Viviparous, lays an egg inside bodycavity and it hatches before birth
Describe the defining characteristic of amniotes
Egg the defining characteristic
* Permeable egg, enabling featurs to breath air
* Chorion allantois and amnion still in modern mammals who dont lay eggs
* Waste products put into the allantois
Limitations on size due to complexity so not too small and also gas diffusion needs to occur so cant get too big
Name some of the key changes from amphibian to reptile
- Dont metamorphosise
- Lay the eggs on the land with internal fertilisation
- Eggs can be hard or leathery
- Develop extra embryonic membranes for the embryo
Name some of the skeletal distinctions that equipped early reptiles for life on land
- bigger wider hip and shoulder gurdle
- larger hind and fore limb
- strongr vertebral column
Alongside stronger bones and less seized bones
Name some of the biological/anatomical charcteristics of reptiles
- Keratinised scale, waterproof, no gaseous exchange
- Single joint for neck - ossified skeleton
- Larger convoluted lungs
- Improved circulation, better separation between pulmonary and systemic systems
- But still ectothermic
- Internal fertilisation
- amniotic eggs, no aquatic larval stage like their predecessor amphibians
*
Who are the anapsids? Can you remember any species?
Turtles only ones alive today
- usually characterised by no holes in the skull aside from the eye sockets
- Extinct species include Procolophodon +
Scutosaurus
Describe order Testudines?
They are the turtles, part of the subclass anapsida.
- Fused ribcage to create shell called carapace
- oviparous
- lungs contracted by muscles instead of rib cage
Who are the diapsids?
Extant clade containing the reptiles. Originating in the upper carboniferous.
- had a late permian diversification with things like the Coelurosauravus, the gliding lizard
- contains the order squamata
Who are the Squamata?
An order of reptiles
* contains sub order sauria
Describe the suborder Surpentenes
In the Order Squamata. Snakes.
- Ribs along length of body
- Limbless
- Kinetic skull allows diverse feeding mechanisms, can thrust feeding glottis forwards
- Cornea protected by membrane so no blinking
- Chemosensory epithelium, tounge places particles onto organ
- Detect heat from pray
Who are the Archosauria?
birds, dinosaurs and crocodilians.
Describe the anatomical features of dinosaurs
- synapomorphies in bone structure such as their distinctive femur
- Unique rear skull
- Radius shorted than 80% of humerus length
Unique bone structures - Homeothermic
What are the two branches of dinosaurs? and what distinguishes them?
Saurischia
* Lizard hiped (angled pelvis)
* Upright theropoda
* Quad sauropodomorpha
Ornithischia
* Bird hipped
* Quadrapedal
* Herbiverous mainly
When are the earliest true dinosaurs?
(early) Late Triassic
E.g. Eoraptor
E.g. Herrasaurus
What are the major differences between birds and reptiles?
- Endothermic
- 4 Chambered heart
- Feathers, which are different to the extant non-avian reptiles
Name some similarites between birds and reptiles
What is the semilunate carpal?
Its the biggest piece of evidence that birds diverged from the arthropod lineage
- is a half moon shaped bone in the wrist that promotes flexibility
- it clearly formed via a fusion of two dinosaur wrist bones
What features showed the evolution of dinos into birdies?
Sinosauropteryx prima
* First feathered non avialian dinosaur
* Filamentous feathers, likely for insulation
Caudipteryx zoui
* Non-avialian therapod
* More modern feathers
* Large animal
Protarchaeopteryx
* Hollow bird-like bones, to enable fight?
* Feathers with symmetrical vanes
Avialae
* First evolution/appearance of flight
Archaeopteryx
* Darwins missing link between reptiles and modern birds
* Flat sternum which suggests flight muscles were much smaller, maybe too small for flight, maybe just gliding
* Asymmetrical feathers mean more adapted for flight
* Pneumatized (hollow?) bones
The confusciusornithidae
* Larger pectoralous muscles
* Sternum not yet keeled (extended)
The Enantiornithines
Alula (manouvarable flight) and pygostyle more evidence for flight by this stage
Hesperonithes
* Small wings (aquatic birds)
* Sharp teeth, fish eating
* Only mesozoic birds to colonise the oceans
What are the two Superorders of Aves
Palaeognathae and Neognathae
What is the main distinguishing characteristic of palaeognathae from naognathae?
Palaeognathae has a vomer that is fused to the palatine bone
Describe bird eye/vision
- Better vision
- 3 eyelids
- Large eyes
Indented fovea
- see ultraviolet and has four types of cones
Describe the transitions from reptiles to mammals
Synapside
* Simplification of skull bones in mammals * Movement to chewing based eating * Indications of specialisation of teeth
Therapside (mid-permian to triassic)
* Movement to an erect gait, standing up * Larger cerebellum, smarter? * More jaw muscle
Cynodonta (triassic to mid jurassic)
* Loss of lumbar ribs
* Post canine teeth for chewing
Early mammalia (triassic to present)
* Hair
* Mammary glands
* Diphyodont (two sets of teeth)
* Jaw articulation?
Mammalia
* Bigger brains (neopallium
* Monotremes
* Ear ossicles x3
What are they key characteristics of mammals?
Key characteristics of mammals
* Mammal glands, specialisation of sweat glands
* Occiptital condyles: distinctive bone structure
* Ossicles, the ear bones
* Normall 7 vertebre in the neck
* Fused pelivs
* Diphyodont teeth, first set we loose, keep second set
*
Types of glands in mammals
- Eccrine glands, mainly water, mainly cooling/gri[
- Sebaceous glands, keep skin protected via sebum
- Scent Glands: marking and communication
- Mammary glands
Describe mammalian reproduction
What are the subclasses of mammals?
What is the name for lizard-hipped and bird-hipped dinosaurs? Descibe their basic differences
Saurischia
* Lizard hiped (angled pelvis)
* Upright theropoda
* Quad sauropodomorpha
Ornithischia
* Bird hipped
* Quadrapedal
* Herbiverous mainly
