Amniotes Flashcards
Who is an amniote
- Reptiles (sauropsids)
-turtles
-lizards and snakes
-crocodiles
-birds - Synapsids
-mammals
When did amniotes first appear
Carboniferous era only 20my after first tetrapod
Major radiation in the Permian
3 synapomorphies of amniotes
-amniotic egg
-characteristics of their skin
-ventilation: rub based ventilation or costal ventilation
Non-amniotic egg (amphibians) parts
-embryo with yolk sac originating from embryo (extra-embryonic membrane)
-Vitelline membrane
-thick-jelly layer (remains moist in water)
Gas exchange in the Non-amniotic egg is _______
Limited
-oxygen has to diffuse from water through the jelly like layer to the fluid surrounding the embryo to the embryo itself. Carbon dioxide has to do opposite.
-movement is mostly passive through diffusion but exchange of gases is slow
Amphibia embryos have a _____ metabolic rate
Low
-hatch at earlier developmental stage so they do not asphyxiate from lack of oxygen
Amniotic egg structure and functions
-shell: semipermeable protection that limits water loss and allows gas exchange
-albumin (egg white): shock absorption
-chorion: high vascularization gas exchange
-Allantois: stores metabolic waste, highly vascularized gas exchange
-amnion: inner case that encloses the embryo, protective and stable fluid environment
-yolk sac: energy
Which parts of the amniotic egg are extra-embryonic membranes?
Chorion
Allantois
Amnion
What extra-embryonic membranes are present in reptiles and mammals
Chorion
Allantois
Amnion
Amniotic egg advantages
-resists dedication
-source of calcium
-mechanical protection
-increased capacity for respiration: membranes specialized for gas exchange
-larger, faster growing embryo
-bypass larval stage
Amniote form of reproduction
Internal fertilization: eggs are fertilized in female before shell or placenta form
Amniote skin
External layer of skin and scales consists largely of keratin and lipids (keratinized cells=hard dead layers of epidermal cells)
-waterproof skin
-forms protective layer
-repels heat, water, physical attack and microorganisms
-conserves moisture
Amniote changes in respiration
Lungs are primary organ of ventilation in most amniotes. Lungs of amniotes have more surface area than the amphibian lung. Amniote a rely on different mechanisms to ventilate lung.
-costal ventilation
Costal or rib ventilation
Moving lungs up and down to inflate and deflate
Buccal pumping in amphibians
- Inspiration: nostril open, glottis closed, depress floor of mouth which expands Buccal cavity and draws air into mouth
2.inspiration 2: nostrils close, glottis opens, lifts floor of mouth, which pushes air into lungs.
3.expiration: depress floor of mouth, fill with air - Expiration 2: nostrils open, glottis closes, lifts floor of mouth which pushes air out through nostrils
Intercostal muscles
Located between ribs, move chest wall
-external intercostal muscles raise ribs, expands chest cavity and lungs, drawing in air (inhalation)
-internal intercostal muscles depress ribs and decrease space in chest cavity, forcing out air (exhalation)
Costal ventilation if more effective at______than Buccal pumping
Eliminating CO2 from lungs
Enabling Independence from cutaneous respiration, permits thicker skin that conserves water
3 important synapomorphies of amniotes
- Amniotic egg
2.skin
3.Respiration (intercostal)
Temporal fenestration
Holes in the head posterior to the orbit
-has two apsids or arches called temporal bar (arch) lying below and between holes
Diapsid
Two temporal archs in a skull
All living reptiles
Anapsid
Synapsid
Diapsid
Without arch
-ancestral amniotes, ancestral sauropods
Single arch
-mammals, extinct synapsids
two arches
-lizards, snakes, crocodiles, birds
What kind of fenestra do turtles have?
Living turtles have no opening, but are still considered diapause because extinct turtles had two openings. Secondarily derived trait to not have them.
What is the name of the group that turtles belong to
Testudines
Oldest potential ancestor of turtles and why was it significant to find
Eunotosaurus from the Permian had a diapsid skull atypical of extant turtles and it had no shell.
Carapace
Plastron
How are they both made
Incorporates ribs and spine vertebrate to make up top shell of turtles
Bottom shell of turtle that evolved separately
Made of bone that is covered with epidermal scutes.
Can turtles use costal ventilation?
No-shell prevents turtles from costal ventilation because ribs are fused to the carapace and turtles have no intercostal muscles.
What do turtles do to breathe
Muscles (abdominal oblique and serratus) expand the viscera cavity, which lowers the viscera and results in the lungs expanding and inhaling air.
To exhale, other muscles (transverse abdominis and pectoralis) contract the visceral cavity, which pushes the viscera up-and that deflated the lungs
Extant turtles belong to which lineages
Pleurodires-or side necked turtles that retract neck to the side and live in the southern hemisphere and only in freshwater
Cryptodires-hidden necked turtles that pull neck straight back and live in terrestrial, freshwater or marine habitats worldwide
Where do cryptodires move when seasons change
Terrestrial: bottom of ponds
Marine: greater distances to locate species areas for nesting or fessing
Physical adaptations that related to habitat of turtles
Terrestrial: shell domed, feet adapted for digging or walking
Marine: she’ll is reduced in size and streamlined to reduce water resistant. Epidermis is softer and more flexible, but carapace underneath is still hard. Flippers help propel on water.
Freshwater: shell more streamlined than terrestrial. Often walk on lane and dig so they have legs and feet with claws
All turtles have this physical adaptation
Camouflage
Turtle courtships may involve….
Colours, olfactory signs, visual displays, vocalizations, well endowed males
Are turtles viviparous or oviparous
Oviparous-lay eggs, typically in a nest that is buried in sand
Hatching and navigation of turtles
-turtles vocalize in their eggs to synchronize emergence from the egg )many turtles on the beach reduce the probability that any individual will be eaten)
-newborns walk downslope to the water and follow the light (moon) to navigate to the sea, then swim directly into waves. Use magnetic fields to travel and return to hatching beach to next several years later.
No parental care after hatching!!! Except Amazon river turtle
Mechanisms underlying Temperature Dependent sex determination of turtles
-environmental conditions during embryological development (middle third) determines the sex, not environmental conditions at fertilization
-in most turtles, females hatch at higher temps except snapping turtles where males are produced at intermediate temps and females at extremes
-intersex turtles may be born at intermediate temperatures. Some suggest they become male, but sometimes gonads are still undifferentiated months after brith.
Adaptive benefit of temperature sex determination
Turtles that evolved a sex determination strategy resulting in the birth of female offspring at higher temperatures develop faster in eggs, may hatch earlier, have more time to grow bigger as the season progresses and can produce more eggs which results in higher fitness
How does climate change affect turtles
Result in higher temperatures and therefore may cause female-biased populations to be produced. The low number of males make it difficult for members of populations to find a mate.
Direct threats to turtles
-by catch
-hunted for meat
-hatchling walking away from ocean because of bright street lights
-consuming plastic
Turtle life history type
Slow
Tuataras were common in what era?
Squamates (lizards and snakes) expanded during what ear
Triassic and Jurassic
Cretaceous (after Mesozoic)
What lead to the demise of tuatara populations
They live in new Zea lane where there are no rodents or other egg predators. But invasion of rats, cats and foxes causes their pops to decline.
What symbiotic relationship do tuataras have
Sometimes make homes in sea bird colonies and may rely on insects found in burrows made by the birds
Tuatara retain what ancestral trait?
Two skull temporal openings (diapsid skull). All other diapsid (lizards, snakes and birds) have a derived diapsid skull and the two openings are no longer present
What do tuatara have to regulate daily and seasonal cycles
Parietal eye with retina, lens and nerve endings but not used for seeing
What type of life history do tuataras have
Slow
What type of development do tuataras have
Oviparous- eggs take 5-11 months to hatch. This variation depends on temperature because they are ectotherms.
Tuatara and temperature dependent sex determination
Tuatara develop into females at a lower temperature (opposite of turtles)
What are the two groups within Lepidosauria
Squamata-lizards and snakes
Tuatara
How has squamata evolved separately from tuatara
Evolved to lose one (lizards) or both (snakes) temporal openings which is associated with their developing kinetic jaws
Reproduction is squamata
Males have a paired hemipenis help inside their cloaca except when bei mg used. They are paired but single is used during copulation.
Female snake have a paired hemiclitortis too!
Lepidosaurs are usually oviparous but some cane be viviparous (colder temp common)
Family Iquanidae
-feeding
-habitat
-Larger and more herbivorous than lizards: enlarged hind gut with caecum to allow for bacteria to have more time to ferment
-western hemisphere
Family Chamaeleonidae characteristics
-change colour
-rotate eyes independently
-ballistic tongue
Anoles
Have dewflaps that can spread out under their chin. They are usually brightly coloured and used in courtship and terrestrial displays.
Geckos
-nocturnal, arboreal, insect eating
-specialized foot adaptation to stick to surfaces: feet covered in elastic hairs ending in spatulae. Molecular interactions called van der waals forces at the tips of spatulae enable them to move at steep angles on surfaces
Skinks
-found all over world
-some have reduced limbs
-many can she’s their tails when attacked
-45% viviparous
Caudal autonomy
Skinks and other squamates have evolved caudal autonomy (self amputation of the tail) to distract predators while escaping.
They can do this because all but the first 4-9 caudal vertebrae have fracture planes, the muscles are segmented, the arteries have sphincters on either side of breakpoints and veins have valves. Bending the tail sharply to one side starts the break.
The tail piece twitches rapidly for a few minutes to distract the predator
Limbless lizards travel by _________
Independently moving their skin and inner body
Members of the monitor lizard family are often active ______
Carnivores with a high metabolic rate
Variable in size from 10cm to Komodo dragon
All are active predators with well developed limbs and long necks. They are active hunters and search for prey. They have higher blood pressure and metabolic rate to allow for this lifestyle.
How do Komodo dragons fill water Buffalo
Inject venom when biting the animal
Snakes evolved from what
Subterranean lizards with reduced eyes
4 types of snake movement
- Lateral undulation: move head side to side and body follows
- Concertina locomotion: stretch far with their head, hold on to something, then pull the rest of their body close to their head
- Rectilinear locomotion: hold onto ground with underside of body, while moving rest of body forward
- Side-winding locomotion: throw their head forward and are constantly in motion, (s) shape
Lepidosauromorpha includes what
Archosauromorpha includes what
Lepidosaurs, ichthyosaurs, plesiosaurs
Turtles, crocodiles, pterosaurs, dinosaurs
Lepidosauromorpha habitat
All marine
Mososaurs
Lepidosauromorpha
-squamates (same family as monitor lizards)
-predators with highly kinetic skulls
-lived in shallow continental seas
-aquatic derived forms had paddles
-viviparous
All marine tetrapods during Mesozoic were….
Sauropsids
marine reptiles dominated seas during ________ era
Mesozoic
Adaptations to marine reptiles (Lepidosauromorpha)
-streamlined body
-reduced limb bones, digits expanded to form paddles
-nostrils shifted more dorsally and posteriorly
-all viviparous
-plesiosaurs
-icthyosaurs
Placodonts
-coastal species
-vegetation and invertebrate diet
-bony protection on dorsal and ventral side
-Lepidosauromorpha marine reptile
Crocodylomorphs
-only marine radiation of archosaurs
-abundant from Jurassic to cretaceaous
-streamlined head, paddles and fishlike tail
-elongated, reinforced skulls
-massive jaw musculature
-good predators
Extant crocodylians can be distinguished how?
What does this group include
Distinguish families by jaw width
Crocs (more mobile on land) and gators
How do crocodylians capture prey
-ambush from waters edge
-pull prey down to drown or use death roll
Adaptations to snake body to allow for shape
• left lung reduced or absent
• gallbladder is posterior to liver
-right kidney anterior to left
-gonads similar
Snake eyes and ears
-no eyelids: have upper and lower transparent eyelids that are fused
-no tympanum, but have colmnella (stapes) that form connection to inner ear. Can hear 100-700hz
Chemoreception of snakes
Vomeronasal organ:
- a chamber that is above the roof of the mouth. Two ducts in the roof of
the mouth lead to this chamber. A snake uses its forked tongue to gather molecules from the air, and
then brings its tongue to these ducts and the VNO. This way, the snake can detect pheromones (re
mates) or chemicals associated with its prey.
Pit organ
In vipers, boas and pythons
specialized heat-sensitive
organs called pit organs, which are located between their nostril and eyes
organs are extremely sensitive to infrared energy and can
distinguish very small differences and use this to track prey
3 foraging strategies of snakes
- Grab and swallow live prey
- Kill prey first: constriction
- Inject venom
Aposematism and mimicry in snakes
Warning colours to indicate venomous
Some snakes adapted to have similar colours to pretend to be poisonous snakes
Red and black-venom lack
Red and yellow-kill a fellow
Extant crocodilians are similar in what ways to crocodiles from Mesozoic
-semi-aquatic predators: ambush at waters edge and pull down or death roll
-complete secondary palate: can breathe through nose when mouth filled with water or food, or sneak up on animals with only nostrils above water
Crocodilians-social behaviour
Highly vocal in courtship and terrestrial displays
Crocodilians development style and parental care
Oviparous: temperature dependent sec determination (intermediate temps=male)
Maternal care:
-buried best after eggs are laid
-responds to distress calls of hatching going
-helps carry young to water
-female may guard guard for 2-3 years
Pterosaurs-the first vertebrate with _____
Flight
NOT A DINOSAUR
Pterosaurs
-time period
-wing span
-diet
Late Triassic to end of Cretaceous
25cm-10m wing span
Diverse diet of fish, insect eaters, terrestrial vertebrates, fruit and mollusks
Are pterosaurs ancestors of birds?
NO!!!!!
Rhamphorhyncoid (Rhamps)
-Basal forms in late Triassic of Pterosuars
-long stiff tail
-gull sized or smaller
-teeth
Pterodactyloid (Dacts)
Pterosuars
-derives forms in Cretaceous
-large: wingspans of 10-11m
-convergent features to birds: no teeth, reduced tail, sternum with keel, open spaces in bone (pneumatization)
-many had head crests
Sexual dimorphism in pterodactyls
-Only males were crested
-Implies males used crest to compete for mates, for example by attracting females
Patagium
A membrane made of skin anchored to legs and neck used for flight
Similar to bats and gliding squirrels
How does a pterodactyl wing differ from that of a bird? From that of a bat?
Wings of pterodactyls are made of skin that extends from the upper arm to the forearm: patagium (like bats)
Pterodactyl wing is supported (anteriorly) by the arm bone, and then b an extremely elongated 4th digit (unlike bat)
Unlike birds, no evidence of a feathered wing in pterodactyls
Did pterodactyls only fly?
Also wakes as quadrupeds on the ground
Dinosaurs originated from …..
Small agile archosaurs during late-Permian and early Triassic
Change in hip and ankle structure led to a more erect stance
How did dinosaurs walk
Walked upright on pillar-like legs rather than on legs splayed outward like other reptiles and amphibians
Erect stance could support large body weight and led to longer, faster stride
Two main lineages of dinosaurs
- Ornithischians: bird-hipped
- Saurischians: lizard-hipped
Ornithischians diagnostic characteristics
-herbivorous
-most quadrupeds, some bipeds
-many had armour
-horns
-increased during Cretaceous
Include hadrosaurs: lived in large herds, has skulls with crests that probably serves as vocal resonators
Saurischians diagnostic characterisitics
Sauropods
-quadrupeds
-herbivorous
-largest terrestrial vertebrates known
Include brachiosaurus and argentinosaurus (long necks)
Theropods include what current group of animals
-birds are theropod dinosaurs
Theropods diagnostic characteristics
-carnivores
-bipedal, short fire limbs
-tail for counterbalance
Include T. rex and velociraptor
Dinosaur social communication
-colours and patterns in skin or feathers
-crests on head, necks or backs
-inflatable tissues and extensions of nasal passages could have been used to resonate sound
All implies highly sociable
Dinosaurs development store and parental care
-oviparous: many nests with eggs found
-sitting on nest of eggs to keep warm
Cretaceous Terrestrial Revolution (KTR)
120-80mya
-flowering plants (angiosperms) appeared in early Cretaceous; formed 80% of plants by end of Cretaceous
-Increase in insects and appearance of social insects; terminates, ants and hive-forming bees
-major radiations in reptiles and mammals
3 groups come to an abrupt demise at the end of the Mesozoic (Cretaceous era). This includes….
Who survived
Saurischians, ornithischians, pleiosaurids
Birds survived!!
K-Pg mass extinction
Cretaceous-Paleogene Extinction
-66mya
-occurred at end of Cretaceous
-disproportionately affected large animals: those weighing more than 10kg. Exceptions to this are crocodiles and large turtles.
-those that disappeared: all non-avian dinosaurs, all Pterosuars, all marine reptile, 75% of bird families, larger mammals
What vertebrates survived the K-pg
-Sauropsids (mostly smaller forms): crocodilians, turtles, Lepidosaurs (tuatara, lizards), smaller birds
Other vertebrates: lamprey, hagfish, Chondrichthyes, osteichthyes, lissamphibans, smaller mammal
Insects
What caused K-of extinction
A 10-15 km diameter asteroid hit the earth 66mya
Evidence: iridium (common in meteors) at the K-pg boundary, crater, tektites (shocked quartz from extreme impact surround crater)
