Vertebrates Flashcards
Describe Chordata
Deuterostomes, notochords (rod along dorsal axis), pharyngeal gill slits, thyroid
Name 3 chordate orders
Cephalochordate, urochordata, vertebrata
Vertebrates have a neural crest, describe it
Migratory multipotent cells that form around the developing neural tube. Leads to formation of teeth, heart, nerve (all vertebrate characteristics)
Describe 4 vertebrate characteristics
segmented brains, paired sensory organs, branchial arches, (most) vertebral column
Name the two categories of vertebrates
Cyclostomata (jawless, more primitive) and Gnathostomata (jawed, more derived)
What are the two types of Cyclostomata?
Lampreys and Hagfish. Monophyletic.
Describe lampreys
Eel-like morphology, oral sucker, undergo metamorphosis
Describe hagfish
Worm-like morphology, blind, neural crest, produce slime
Describe some features of the skeletal tissues of Gnathostomata
Ribs, ventral vertebrae, hinged jaw, bone and dentine
Describe some features of the soft tissues of Gnathostomata
Myelinated nerves, adaptive immune system, stomach
Name three mating behaviours of fish
Parthenogenesis (‘virgin birth’), sexual parasitism, semelparity (mass breeding event then death)
Name four types of rearing behaviours of fish
Oviparity, ovuliparity, viviparity, ovoviviparity
Describe euryhaline fish
Can live in a range of salinities
Name a behaviour that fish use to avoid predation
Schooling
What kind of fish are Teleosts?
Ray-finned
Describe Teleosts
Mobile premaxilla for protrusion feeding, homocercal (equal-lobed) tail that develops on ventral surface
What are the two categories of Teleosts?
Acanthomorpha (spiny ray-finned, includes seahorses, cod) and non-acanthomorpha (includes eel, catfish, dragonfish)
What are osteichthyes and how do they control buoyancy?
Bony fish. Swim bladder for gas exchange (homologous to lungs)
What are chondrichthyes and how do they control buoyancy?
Cartilaginous fish. Large oily liver for neutral buoyancy. Swim up and down.
What is the difference between anguilliform and ostraciform fish?
Anguiliforms use whole body to swim, high acceleration, low manoeuvrability (eels), ostraciforms are box shapes and only use their tail, low acceleration, high manoeuvrability (sunfish)
Discuss the convergent evolution of fish morphologies
Related to stable mode of life in niches. Convergent evolution arises from repeated niche occupation by different species. e.g. nektonic planktivores (Anomalocaridids in Cambrian, baleen whales in the present)
What phylum contains tetrapods and what are the two types?
In phylum Chordata. Amphibians and amniotes
Where did tetrapods evolve from and when did they first come on to land?
Arose from Sarcoptergians (lobe-finned fish). First on land in the Devonian
What fossil evidence is there for the evolution of tetrapods from Sarcopterygians?
Skull bones, amphibian limb from fin, opening to nostrils in mouth, lungs for air in shallow water
What were the requirements for the movement of tetrapods onto land?
Terrestrial locomotion, air-breathing, structural support, water balance
What did the late Devonian Eustheropteron show evidence for?
Body support in fins (fin exoskeleton) used when the water periodically dropped
What the the early-late Devonian Panderchthyes show evidence for?
Tetrapod-like tail and shoulder.
Describe the structure of the tetrapod skull
Skull structure linked to breathing and feeding. Unattached to shoulder girdle (allows foraging). TETRAPODS HAVE NECKS
Describe the evolution of tetrapod breathing
Gill arches reduce in size/number, invaginated lungs evolved in placoderms and bony fish in Silurian and Devonian (tidal flow is not as efficient as unidirectional flow. Pumps added)
Why do tetrapods have interlocking vertebrate and distinct vertebral regions?
Transfer forces and different loading regimes
Describe amphibians
Ectothermic vertebrates with aquatic larval stage that metamorphoses into terrestrial adult. Thought to be monophyletic. No obvious fossil ancestor.
What do the three categories of amphibians have in common?
Pedicellate teeth
How do amphibians respire?
Via skin, gills, and lungs
Name two similarities between amphibians and other tetrapods
Fenestration on back of skull, 10 cranial nerves
Name two adaptions of amphibians
Different heart structure to endotherms. Limbs for land locomotion
Describe the amphibian order Urodela (Salamanders)
Not always aquatic->terrestrial, can have paedomorphosis, prehensile tongue, single common ancestor in mid-Jur
Describe the amphibian order Gymnophonia (Caecilians)
Secondarily limbless (lack girdle and limbs), burrowers, viviparity, can concertina back bone internally, skin feeding
Describe the amphibian order Anura (Frogs and Toads)
Tailless adults, aquatic reproduction, jumping, large orbitals, no ribs, fused ulna-radius and tib-fib, max. 10 pre-sacral vertebrae
Describe amniotes
Egg-laying tetrapods. Egg-laying allows them to be fully terrestrial.
Describe reptiles
Ectothermic tetrapods with dry scaly skin and that lay soft-shelled eggs on land. Eggs have two membranes so less size restriction from O2 diffusion.
Describe the evolution of reptiles
Originate in Carboniferous, diverse taxa in Mesozoic, 3 branches in Permian, modern groups in Triassic
Define anapsids and give three examples
1 skull hole. Stem reptiles, turtles, tortoises
Define euryapsids and give two examples
2 skull holes. Ichthyosaurs, Plesiosaurs
Define Diapsids and give six examples
3 skull holes. Crocodilia, snakes, lizards, pterosaurs, dinosaurs, birds
Define Synapsids and give two examples.
4 skull holes. Mammals and stem-mammals
What preadaptation did amniotes have to have?
No metamorphosis, internal fertilisation, Ca deposit to build shell
Describe early reptiles
Robust limbs, no swimming, less sprawling gait
Give six examples of reptile characteristics that amphibians don’t have
More advanced body support, copulatory organs (internal fertilisation), complex nervous system, efficient circulatory system, jaws, no larvae
Describe the reptile order Testudines (Turtles)
Oviparous, carnivorous, shell of fused ribs, flexible neck, anapsid.
Describe the suborder Sauria (lizards), contained in the reptile order Squamata
Ectothermic, good vision, moveable eyelids. Includes Amphisbaeia (legless lizard, no visible eyes or ears)
Describe the suborder Serpentes (snakes), contained in the reptile order Squamata
Limbless, no girdle, rigidity from ribs, kinetic skull (python has mobile jaw), don’t blink, can be venomous, can sense body temperature
Describe the reptile class Archosauria
Contains Crocodilia (largest living reptiles), dinosaurs, and birds. Diapsids.
What was the ancestral state of dinosaurs
Bipedal
Give two synapomorphies of dinosaurs
Large single occipital bone in back of skull, radius length < 80% of humerus length.
What are dinosaurs?
Endothermic (easier to keep warm than cool as a large animal), diapsid archosaurs
Define and give examples of Saurischia
Lizard-hipped. Pubis points forward. Includes sauropods, T-rex, allosaurus. EVOLVE INTO BIRDS
Define and give examples of Ornithiscia
Bird-hipped. Pubis lines up with ilium. Several lineages revert to quadrupedality. Includes ceratopsians. DID NOT EVOLVE INTO BIRDS.
Give three techniques for estimating body mass of extinct animals
Scaling, trace fossils, bone strength
What adaptations did sauropods have for their long necks?
Valve system to maintain blood pressure up to head, springy tendon in neck so head up was relaxed state, small, light skulls
What may dinosaur horns and frills have been used for?
Sexual selection, fighting, ramming, protection
Describe theropods dinosaurs
Hollow bones, three digits on each limb, semilunate carpal for wrist flexibility. Evolved into birds
Name three characteristics present in birds and not reptiles
Endothermy, feathers, 4 heart chambers
Name three similarities of birds and reptiles
Egg-laying, leg scales, columella (single middle ear bone)
Describe the evolution of flight in birds
Filamentous insulating feathers -> symmetrical hind limb feathers -> feathers with symmetrical vanes, hollow bones -> asymmetrical vanes, pneumatised bones (Archaeopteryx, 150-145mya)
Give three synapomorphies of the clade Avialae (birds)
Flight, 25 or less vertebrae, 1 reversed digit
Describe the Avialian Confuciusornis
Early Cretaceous. Early birds, toothless beak
Describe the Avialian Enantiornis
Most abundant avialians in Mesozoic
Describe the Avialian Hesperonithes
Only Mesozoic birds to colonise water. Transitional shorebird that evolved into modern birds.
Name the two categories of modern Aves
Palaeognathe (6 orders. ratites, more primitive) and Neognathae (27 orders. water birds, ducks, soarers, forest birds, game birds)
Describe the Avian skull
Columella (single middle ear bone), keratinous beak relating to feeding, syrinx produces sound
Describe Avian vision
Superior vision to other vertebrates, tetrochromats, 3 eyelids
Describe four Avian adaptations for digestion
Crop (softens and regulates flow of food), gizzard (muscular stomach as no teeth to chew), caeca (bacteria to breakdown plant cellulose), cloaca (opening for excretion). Excrete solid uric acid to prevent water loss.
Describe Avian reproduction
Internal fertilisation, extensive parental care, precocial (mature) is ancestral state, now range of precocial to altricial
