Chordates - Biodiversity
What is the chordates closest relative
Echinodermata - Sea stars and sea urchins due to having the most recent common anscestor
These are the only 2 deuterostomes
When did chordates first appear
First appeared in the cambrien era and therw are now 50-60,000 species
What are the notochords
These are 1 of the common derived chriodate traist that all have during embryonic development
They are longitudinal flexible rods between the nerve cord and digestive tube
Provide support for muscles to work on and not found in humans
Composed of large fluid filled sacs
What are dorsal nerve cords
These are 1 of the common derived chriodate traist that all have during embryonic development
They are developed by invagination of the dorsla ectoderm and are a hollow nerve cord that then develop into the CNS
What are Pharyngeal slits
These are 1 of the common derived chriodate traist that all have during embryonic development
Slits in the pharnyx to allow water to exit without enetring digestive tract and so can be used for filter feeding
They have been modified to gills in lower vetabrae
This what our ears evolved from due to went slits , gills, jaw , ears
What is the post anal tail
Muscle that extend beyond the anus to provide a propeling force for aquatic chordates
Non-chordate have digestive tract the full length of the body
What is Segmentation
The more segmentation is an indiactor of how many times the species evolved and is in humans
What were the earliest know chordates
Pikaia and Cathaymyrus both from 540 mn years ago
Both filter feed whilst swimming and were smal
What are Urochordata
They are sea squirts and tunicates that filter feed
They only have the pharyngeal slit out of the 4 common chordate traits
But the larvae has all of the chordate traits that then go during metamorphosis
What are Cephalochordata
These are lancelets that are plankton feeders and burrow in the sand
They have a somewhat brain at the anterior tip of the nerve cord
30-35 species
What are the craniata in the cephalochordata
They are pharyngeal slits that are modified to gill slits
They is a skull and head so evidence of cephalization
What are Haikouella
They have brain and eyes but dont have a skull and were found in China
A member of the cephalochordata
What are Mzxini
These are Hagfish and so have no jaw or vertabrae but do have a cartilage skull
Feed of sick or dead fish and have slime production as defence method
What are the verebrata
These all have a more extensive skull and have a vertabnrae in additon or to replace the notochord
They have ratys in the fins so are stiffer
What are Cephalaspidomorphi
These are lampreys that are parasites that live on fish and have a cartilage skeleton
Have a cartilage pipe around the notochord that also enclose the nerve cord
What are conodots
These are abundant tooth like fossils from late cambrien era to the triassic era
They all fit together in the mouth of early animas and is first instance of mineralisation due to not made of cartilage but minerals
What are vertabraes
These are chordates that have a vertbrae but nothing else after that
What are Gnathostomes
These are chordaytes that have evolved further than vertabae to have a spine to have a jaw
This was done due to gill slits support the modification to jaws and then greater mineralisation of the endoskeleton
There is also a 2 sets of paired fins
What are Placoderms
These are exsinct gnathostomes that were up to 6M long and the first evidence of internal fertilisation
What were acanthodians
The other species of exstinct gnathostomes that were less armoured and smaller than placoderms
What are Chondrichthyes
These are sharks and Rays + Ratfish with 1000 species
They have a mostly cartilage skeleton that is impregnated with calcium
They are mostly marine but some freshwater species as well
A extstinc close relative to Ratfish called helicoprion that could renew its teeth in lower jaw
What are Actinopterygii
These are the ray finned fish with 30,000 species with a fully mineralised endoskelton
What are Ray finned fish
They all have varying life styles and have 3 of the 4 chordate trait
They have a swim bladder bladder and a homologous lung with many bones in the skull
What are Sarcoptergyii
These are lobbed finned fish with up tio 20,000 species
There are 2 lineages in the group: Dipnoi , Actinistia ,
They all have rod shaped bonded surrounded by muscles
What are the actinistia
There are 100 species but onky 2 remaining
What are Dipnoi
These are lungfish and are 6 species
Have gills but can also breathe air due swim bladder that act as a lung
Can cocoon in mud shell to survive a drought for long time
What are Tetrapoda
These are the gnathostomes with limbs and feet and are the most modified lobe finned fish and are 20,000 species
The gill slits support modified ear bones
Why was the conquest of land hard
Due to gills dont work out of water
Their is the problem of drying out
The fertilisation of eggs and embryo survival
Body weighs more on land than in water
What are the Amphibia
These are frogs and salimanders
The adults live on land and have lungs and skin whilst tjhe larvae live in the water and breate through skin and gills befoire metamorphisis
What are the amniota group
These are the reptiles+ mammalss that breathe throigh lungs
They have scales to stop dessication and the embryo enveloped in membranes
There is no obligatory water stage in the life cycle
Appeadr in carniferous ear 365 mn years ago
What is the amniote egg
There is extra protection by the shell
It needs internal fertilisation
The extraembryonic membranes protect embryo from dessication and damage
What are some Reptile lineages
Dinosuars = exstinct = Parareptiles, Pterosaurs, Plesiosaurs and Ichthyosaurs
Living linages = Snakes and lizards, Crocodiles, Turtles, Birds
Further chordate evolution groups
Gnathostomes all have vetabrae and a jaw
Sarcopterygians all have added lobed fins added
Tetrapods all have growing limbs from the lobed fins
Amniotes all have envoloping embryo in membrane and radiation of amniotes after land conquered
What are mammalia
These are all the mammals = 5000 species
These produce milk for offspring and are endothermic
They have hair covering the skin
Mostly are Viviparous so give birth to live offspring
What are the exstinct Synapsida
These are mammal like reptiles that have no hair
Tjese were dominant tetrapods during the permain ear
How is the mammalian skull made
Is made by simplification of relativce skulls due to only 34 bones in the skull
What are Monotremata
These are platapus and are oviparous
Have hair and produce milk but no nipples
Found in Australia
What are Marsupialia
These Kangaroos, Koalas, Possoms
The new born move into a pouch for a second pregnancy as it lachted onto the nipple
Found in Australia and americas
What are Eutheria
All these animals are placental mammals and Viviparous
The embryo develop in the uterus and fed via Placenta
Why have eutherian mammals been successful
Independent from environment due to effcient circulatory system
Have a relative large brain size for behaviour adaptations
Teeth differentiation = Incisors, Molars , Premolars and Canines
What are Carnivores
These have teeth for killing prey and tearing meat
Found in Carnivoria) Cats and Dogs )and Pinnipedia (Seals)
What are Piscivores
Have teeth adapted for catching fish
Cetacea= Dolphins
What are Herbivores
Teeth for grinding vegtable material
=Artiodactyla ( Deers and Reindeers), Perissodactyla ( Rhinos ) , Proboscidea ( Elephants)
Teeth for chiesseling and Gnawing
= Rodentia(Squirrels) , Lagomorpha ( Rabbits)
What are Omnivores
Teeth for multi-purpose so meat and veg
Primates ( Monkeys, apes and humans )
Why are teeth a good indicator of evolution
Mammals have evolved teeth in differing shapes and sizes depending on food they eat
Enrelated mammals eating the same thing have similar teeth= Cnvergent evolution and adaptive radiation
Why are Dogs important
Most morphologically variable animal species
More variation in 1 species than there is across some genera in groups
There is evolutionary change reuslting from humans not natural selection
How has flight evolved
Has evolved independently 5 times
Insects were the first to evolve then, dinosaurs, bords, mammals then fish
What are Theropods
A group of dinosaurs containing birds and the t-rex
Archaeopteryx have a typical theropod skeleton and feathered arms and tail
Were capable of flight due to asymmetric feathers but was weak flier
Why have dinosaurs not gone exstinct
Taxon dinosauria never went exstinct all groups except the brids that have to be on the taxon to make it monophyletic
How have feathers evolved
They have evolved from scales initially for insulation and then later adapted for flight
Flight more likely to have come from the trees down rather than ground up
What is needed for flight to happen
Need asymettric feathers tro create an aerofoil
They need to be low weight by having air scas in bones and muscles
Get the energy from the endothermy
Birds dominate the air 9500 species
How is Dinosaur endothermy described
Origianlly thought to be reptile so cold blooded pressumed
The bone structure show endothermy
The larger species relying on bulk endothermy so variation in the levels of it
Bills can adapt for differing purposes like teeth
They are an example of adaptive radiaton and convergent evolution
Filter feeding Bills
These are for ducks and flamingoes
Have lamellae un the beak to filter the food by pump water through and lamellae catch the food for then the tongue to grab after water leaves
Bills for Nectar drinking
These are for hummingbirds and Sunbirds
Flesh eating bills
These are for owls, vultures and buzzards
Bills for eating insects
Have a snaller bill and for song birds and woodpeckers
Bills for catching fish
For Kingfisher and Herons
Female kingfisher have red bill and male don't
Bills for Seed eating
For peacocks and song birds
Some bills are adapted for all these things
These can eat anythign with their bill
Parrots and are the most intelligent bird
How do darwins finches vary
Have adapted bill size so can vary the type of seed that they can eat
Is adaptive radiation
How have chordates returned to the water
In orcas, penguins and both are streamlined fish shape due to convergent evolution