Amniote Lecture Flashcards
Amniote synapomorphy
amniotic egg (clade-defining)
Amniote monophyletic or paraphyletic?
monophyletic clade
Amniotic egg “synapomorphies” (3)
(3 new membranes)
- Amnion
- Allantois
- Chorion
Amnion
surrounds developing embryo & holds it in amniotic fluid (“enclosing the pond”)
Allantois
repository for nitrogenous waste
Chorion
gas exchange (together with Allantois)
Other derived characteristics of Amniotes (8)
- keratinized skin (resistant to water loss)
- keratinized epidermal scales in reptiles (dermal in bony fishes) (epidermal + dermal in cartilaginous fishes)
- hardened nails or claws
- ventilation/respiration via lungs filled by thoracic expansion (expansion of rib cage produces (-) pressure)
- no larvae or metamorphosis
- no gills
- loss of lateral line system
- internal fertilization (most w/ intermittent organ)
Amniotes originated in
early carboniferous
3 major groups of amniotes by
later carboniferous (based on skull morphology)
- Anapsida
- Diapsida
- Synapsida
Anapsida =
first amniotes! (extinct?)
Anapsida have no
no temporal skull opening behind orbits (completely roofed by dermal skull bones)
Turtles historically considered
Anapsids
Turtles now considered
derived Diapsids based on new data
- t.f. no extant anapsids
Diapsids have
2 temporal skull openings behind orbits (separated by bony arch)
Diapsids represented today by
all living reptiles & birds
Diapsida =
Testudines, Lepidosauria, Archosauria
Testudines (turtles) monophyletic or paraphyletic?
monophyletic clade
Lepidosauria monophyletic or paraphyletic?
monophyletic clade
Archosauria monophyletic or paraphyletic?
monophyletic clade
Testudines girdle located
w/in rib cage
Testudines lack
teeth (jaws w/ keratinized plates)
Testudines reproduction
oviparous & bury eggs in nests
Testudines sex det
Incubation Temperature Dependent Sex Determination
What groups exhibit Temperature Dependent Sex Determination?
all turtles, crocodilians, some snakes & lizards
Temperature Dependent Sex Determination:
high temp = female
low temp = male
~29 degree switch threshold
Current phylogenetic position of Turtles?
- closer to derived diapsids:
DNA evidence says closer to Archosaurs (crocs & birds)
Morphological evidence says closer to Lepidosaurs (snakes & lizards)
Transitional turtle
Odontochelys semitestacea (“toothed turtle with half shell”)
- most basal turtle
- teeth!
- only bottom half of shell present
Lepidosauria is w/in
Diapsida
Testudines is w/in
Diapsida (current)
Rhynchocephalia is w/in
Lepidosauria t.f. Diapsida
Lepidosauria animals consists of
all non-avian reptiles except crocs & turtles
Lepidosauria =
Rhynchocephalia (tautara) (most basal lineage) + Squamata (lizards)
Archosauria is w/in
Diapsida
Squamata is w/in
Lepidosauria t.f. Diapsida
Serpentes is w/in
Squamata t.f. Lepidosauria t.f. Diapsida
Amphisbaenians is w/in
Squamata t.f. Lepidosauria t.f. Diapsida
Rhynchocephalia aka
“tuatara” aka living fossil
Rhynchocephalia species
one one extant
Sister lineage to Squamata
Rhynchocephalia
Squamata =
Lacertilia (lizards) + Serpentes (snakes) + Amphisbaenia
Lacertilia is w/in
Squamata t.f. Lepidosauria t.f. Diapsida
Lacertilia (lizards) monophyletic or paraphyletic?
paraphyletic group (when snakes & amphisbaenians not included)
Serpentes (snakes) monophyletic or paraphyletic?
monophyletic clade
Squamata integument
periodically shed in 1 or large pieces
Squamata skulls are
kinetic skulls = significant movement of different parts of the skull relative to e/o
Squamata synapomorphies
- hemipenes: paired intermittent organ
- tail autonomy (lost in snakes & in some lizards)
Lacertilia feeding
most insectivorous
some large ones are herbivorous
some carnivorous on large prey
Lacertilia tail autonomy
fracture planes w/in vertebrae (how lizards regrow tails)
Squamata limblessness derived
convegently (evolved independently) btwn snakes & lizards
Amphisbaenia characteristics
- limbless (except one family w/ front limbs)
- one lung (L)
- fossorial (adapted for burrowing)
- robust akinetic skull used as burrowing organ
Amphisbaenia feeds on
mostly invertebrates
Serpentes occupy which habitats
all except antarctic
Serpentes lack (2)
- limbs (some forms w/ pelvic girdle vestiges)
- external ear openings
Serpentes eyelids
fused into spectacle
- lower eyelid of snake always closed & one of the scales became spectacle
Serpentes lungs
only one (R) (opposite of amphisbaenians) - why? no reason, LOL, just happened
Serpentes feeding
all carnivorous
Serpentes amount venomous
only <15%
Serpentes feeding specializations
skull extremely kinetic (parts moveable relative to e/o)
- paired joints on each side of head increase gape
- mandibular symphysis unfused (lower jaws move separately on each side to ingest large prey)
Archosaurian animals
crocodilians, birds, & extinct groups (pterosaurs, dinosaurs, etc)
Archosaurian flight evolved
twice (pterosaurs & birds)
Crocodylia is w/in
Archosauria
Most basal archosauria
Crocodylia
Crocodylia teeth =
thecodont (teeth in sockets)
Crocodylia oviparous or viviparous?
oviparous (egg laying)
Crocodylia sex determination?
temperature dependent
Crocodylia exhibit complex
vocalizations (associated w/ courtship, territoriality, etc)
Crocodylian parental care
nest guarding & taking young to water in mouth
Possible archosaur synapomorphies:
complex vocalization & nest guarding…
both in crocs & birds
Crocodylian secondary palate
separates breathing & eating pathway
birds and mammals are both
endotherms
Shared characteristics between non-avian reptiles & birds
- 1 middle ear bone (stapes)
- mandible (consists of several bones) (articulates w/ quadrate)
- excrete N-wastes as uric acid (urea in mammals)
Dinosaurs monophyletic or paraphyletic?
paraphyletic if birds not included
Therapoda =
various Dinos + birds
Aves aka
birds
Aves synapomorphies (6)
- bipedal
- neck (elongate, mobile, S-shaped)
- pneumatic (hollow) bones
- digitigrade posture (walks on digits)
- furcula (fused clavicles = “wishbone”)
- lunate carpals (allow swiveling movements key to flight)
Most basal bird
Archaepteryx
Archaeopteryx characteristics (therapod & bird)
“old + wing”
- therapod (non-bird) char.’s = thecodont teeth, long tail, clawed digits on forelimbs
- bird char.’s = asymmetrical feathers t.f. probably capable of true flight
(clearly shows bird-theropod relationship)
Neornithes is w/in
Aves
Neornithes monophyletic or paraphyletic?
monophyletic clade (including all extant birds)
Neornithes major radiation during
Cretaceous & early Tertiary
Neornithes =
Paleognathae + Neognathae
Intermittent organ in birds?
not in most (ostriches & ducks do tho)
Paleognathae aka
“ratites”
Paleognathae is w/in
Neornithes t.f. Aves t.f. Archosauria t.f. Diapsida
Paleognathae animals
ostriches (largest living bird), emus, kiwis, etc
Paleognathae flight?
flightless (have flat sternum)
Neognathae is w/in
Neornithes t.f. Aves t.f. Archosauria t.f. Diapsida
Neognathae animals
all other birds (besides paleognathae)
Neognathae flight?
- but…
- & evolutionary pattern?
strong flight muscles (keeled sternum)
- but flightlessness evolved independently (convergently) many times due to loss of keel
- & reversal/secondarily derived
Bird feathers homologous to?
scales of other reptiles
Bird feather origin?
epidermal (t.f. homologous to scales or reptiles)
Bird feathers made of
keratin
Bird feathers are functional when
they are dead
Other bird feather functions:
- thermoregulation (conserve body heat)
- flight (flight feathers)
- social displays (elaborate & colorful)
- bristles around mouth of some birds (sensory function that catches insects in flight)
Bird skeletal specializations
- pneumatic bones (filled w/ air cavities, strong but light)
- skull (lightly built “loss/reduction vs. ancestral archosaurs”)
- teeth lost (replaced by keratinized beak)
- axial skeleton (sternum w/ carina “keel” for powerful flight muscle attachment, & furcula “fused clavicles” that acts as a stabilizing strut)
Birds and endothermic w/
high body temperatures & high metabolic rate (requiring large food intake)
Bird metabolism evolved
- crop = storage chamber @ end of esophagus that increase digestive capacity
- gizzard = compartment of the stomach that grinds food w/ keratinized plates (replacing role of teeth)
Beak evolution due to
feeding specializations
gas exchange in birds is…
the most efficient (related to high metabolic rate and energetic demands)
bird gas exchange modifications (2)
- parabronchi = site of gas exchange (rigid lungs) that increase gas-exchange capacity (huge surface area, & thinnest gas-exchange membranes among vertebrates)
- air sacs = expand/contract to ventilate parabronchi (poorly vascularized elastic structures) increase volume of air sacs several times that of parabronchial lung, making body lighter
pattern of air flow though bird parabronchi
unidirectional & continuous
Structures on bird vertebrae show
non-avian dinosaurs had air sacs in same places as birds
vision in birds
- large eyes (eagles & owls have eyes size of humans)
- high acuity color vision (active & coordinated habits)
- retina w/ high density of rods & cones (to see in difficult to see environments)
birds mate
*but
monogamous
- both sexes equally capable of caring for young
- females gestate young & lactate
- but, DNA paternity analysis shows birds as “unfaithful”
- cuckoldry (poor guy lol)
what 2 things matter most in life????
energy & reproduction!!!!
