Lab 6 Flashcards
Which species are found within the clade Sauropsida?
turtles, lizards, snakes, crocodilians, birds
How are sauropsids distinguished from other amniotes?
- B-keratin
- reduction or absence of supratemporal bones
Crocodilians have what type of skull?
diapsid skull with additional fenestrae (antorbital fenestrae and mandibular fenestrae in lower jaw)
How are turtles unique? What type of skull do they have and why?
- shell composed of carapace and plastron (fused bony pieces)
- anapsid skull (secondarily lost temporal fenestrae)
What are examples of Squamates?
-lizards and snakes
What do lizards have that snakes don’t?
- lizards have moveable eyelids and external auditory opening
- snakes lack both
Birds have what type of skull?
diapsid skull
Mammals have what type of skull?
Synapsid skull
Anapsid vs Synapsid vs Diapsid skulls
Anapsid: no temporal fenestrae
Synapsid: one temporal fenestrae per side
Diapsid: two temporal fenestrae per side
Skeletal modifications and adaptations of extant sauropsids: Lizards
streptostyly jaw
Skeletal modifications and adaptations of extant sauropsids: Snakes
- pectoral girdle absent
- pelvic girdle absent or reduced to spurs
- zygantra
Skeletal modifications and adaptations of extant sauropsids: Turtles
- sternum absent
- secondary palate in some
- plastron and carapace
- coracoid, procoracoid and scapula of pectoral girdle lie within ribcage
Skeletal modifications and adaptations of extant sauropsids: Crocodiles
- clavicles absent
- secondary palate
- gastralia
- palpebral
Skeletal modifications and adaptations of extant sauropsids: Birds
- teeth absent
- clavicles fused to form furcula
- keeled sternum
- synsacrum
- fusion of forelimb and hindlimb bones
The amniote vertebral column is divided how?
cervical, thoracic, lumbar, sacral and caudal region (from cranial to caudal direction)
What is the function of the ribs in amniotes?
muscle attachment, protection of viscera, assist breathing
What do we mean by “true ribs”?
ribs that connect to the sternum
What are scutes? How can they be used for identification purposes?
- keratinized scales that form the outer layer of the shell of the turtle
- number and arrangement of scales are useful characters in identification
What are homologous to reptilian epidermal scutes?
- feathers of birds
- scales on snakes and lizards
Claws evolved from what and when?
a specialization of the epidermis that is not found in amphibians but in higher vertebrates
What are the functions of the scales in reptiles?
- to retain water
- for protection from predators
- allow for movement on land in snakes
What functions might be associated with coloured scales?
- attracting mates
- mimicry to ward off predators (think that they are poisonous)
- camouflage
Function of the sharp ridging on the turtle’s beak?
- since they don’t have teeth, need something to cut through their prey
- can’t extend their tongue to catch prey so instead use their beak
Which parts of the turtle are fused to the bony plates of the carapace? What might this suggest about their evolution?
- fused with endochondral ribs and vertebrae
- carapace is derived from the ribs
Which parts of the turtle are fused to the plastron?
incorporates the only remaining dermal elements of pectoral girdle, clavicles and interclavicles
How do you identify a male turtle from a female turtle?
male: anus opens beyond end of carapace, claws on front feet are longer than hind feet, plastron is flat or slightly concave
female: anus opens at or before end of carapace, front and rear claws are both short, plastron is convex
When a snake eats, what happens to the jaw?
- streptosyly jaw
- jaw doesn’t unlock when eating but quadrate swings
Why do some lizards like iguanas have modified scales with spines?
- deter potential predators
- make it look more intimidating
Snakes generally lack limbs. However, boas and pythons have ______?
small vestigial hind limbs
Describe the difference in scale pattern on the dorsal and ventral surfaces of the snake. What is the function of the shape of the ventral scales?
dorsal: longitudinal plates
ventral: large, long, flat shaped to allow for low friction with the ground during locomotion
Snakes do not have an eyelid. What is the structure called that protects their eyes?
single clear scute
Can snakes hear airborne sounds?
no, they lack a tympanum
How do snakes sense sound?
sense vibrations through the ground
How would you describe the body shape, stance and position of crocodilian limbs?
- lizard-like
- short limbs that are straddled sideways from their body (not directly beneath them like mammals do)
- semi-erect gait (stance halfway between a horse and a lizard)
- bipedal (two feet) stance when leaping or jumping to capture prey
What provides propulsion for a swimming crocodile?
tail provides all the thrust
What covers the nares of a bird?
a fleshy covering called cere
How did feathers evolve in birds?
a specialization of the skin unique to birds
What are the various functions of feathers for birds?
streamlined surface for flight, insulation, confer pattern and colour important for social behaviours (mating)
Why might birds like vultures not have feathers on their head and neck?
feathers are insulating, keeping in lots of heat so having no feathers helps keep them cool
Which feathers of the bird are the largest contour feathers?
flight feathers on the wing
What is another name for the tail feathers of a bird?
retrices
What are the two types of contour feather on the wings of the bird? Name their functions and where they are located.
Primary feathers: on the manus, produce thrust
Secondary feathers: on the forearm, produce lift
What are the down feathers of the bird? What are their functions?
soft and fluffy, lack a rachis, used for insulation, barbules lack hooks and form tangle of air pockets
The feet of birds are covered by what?
podotheca, a thick skin
How many toes does a bird have, and what is special about one of them?
4 toes with one pointing backwards called the halux
Do birds have scales?
yes, epidermal scales on feet and legs
Why do birds have claws?
- perching
- cimbing trees
- carrying food
- manipulating food
Why do birds that can fly have asymmetrical wing and tail feathers?
confers rigidity on the leading edge
What is the difference between the calamus and rachis of the feather of the bird?
calamus=is at the base of the feather and lies beneath the skin
rachis=lies above the skin and is solid
The stapes of the turtle are homologous to what?
homologous with the hyomandibular of fish
What forms the jaw suspension in turtles?
articular and quadrate of lower jaw
Through what structure does the spinal cord of the turtle enter its skull?
spinal cord enters the caudal end of the skull via the foramen magnum
What is the function of the flange on the supraoccipital of the turtle?
for shock resistance
How many occipital condyles does a turtle have?
one
What kind of joint is formed by the occipital condyles articulating with the atlas in a turtle? What motions can occur around this joint?
- atlanto-occipital joint=synovial type joint
- forward and backward nodding of the head, lateral movement
What part of the pterygoid is a reptilian characteristic?
ventrolateral flanges of the pterygoid
What is a choana in the turtle?
the internal opening of the nasal cavity
What forms most of the floor of the orbit of the turtle?
the palatines
How is the nasal cavity enclosed in the turtle?
a ventromedial flange of the maxilla which articulates with the ventral plate of the vomer anteriorly and the ventral plate of the palatine posteriorly
What is the function of the secondary palate in marine turtles and crocodilians?
- divides nasal cavity and oral cavity
- segregates airflow in the mouth when submerged in water
- allows for simultaneous breathing and chewing in water
The coronoid of the turtle has a coronoid eminence on it. What is its function?
allows for muscle attachment
With what does the articular articulate with to open and close the lower jaw of the turtle?
articulates with the quadrate
The hyoid apparatus is composed of? What are they derived from and homologous to?
- derived from hyoid and branchial arches of fish
1) corpus is homologous to basihyal and basibranchial of fish
2) cornua is homologous to first and second ceratobranchials
The humerus of the turtle articulates with what?
glenoid fossa
How many digits and metacarpals does a turtle have?
five
What is the articular socket for the head of the femur? What bones also contribute to this structure?
- Acetabulum
- pubis and ischium
What is the main difference between the caiman skull (crocodilian) vs a turtle skull?
- crocodillian bones in the skull are much more elongated (especially snout) than the turtle
- bones like the premaxilla, maxilla, nasal, frontals are all elongated forming a long thin snout
What is the function of the palpebral in crocodilians?
- a small bone glued to prefrontal
- embedded in eyelid
- gives eye some added protection
Compared to the turtle, the crocodilian’s secondary palate also includes what structure?
-pterygoid through which the choanae open
vomer is not visible in ventral view
What are gastralia?
- floating dermal ribs
- only found in crocodilians
- provide support for the abdomen and attachment points for abdominal muscles
Lizards have lost the entire lower bar of the inferior temporal fenstrae (crocodilians still have this bar). What does this permit?
permits greater mobility of the quadrate with the skull
The tympanum attaches to the quadrate. How is the quadrate adapted for attachment of the tympanum?
it is concave to allow the tympanum to sit inside of the quadrate
True or false? Lizards have a secondary palate.
False
Compared to crocodilians, the lizard skull is different how?
- no secondary palate
- smaller
- reduced squamosal
- superior temporal fenestra is larger
- more pronounced coronoid forming a distinct process
- splenial reduced
On what bones do you find teeth on the lizard skull?
dentary, maxilla and premaxilla
Lizards exhibit a phenomenon called streptostyly. What does this mean?
- as lower jaw drops, quadrate swings forward and snout rotates downward
- increases size of gape and keeps jaws more parallel for more effecient feeding
- maintains tension on tympanum
In venomous snakes, what is different about their teeth?
- have curved fangs to inject venom into their prey
- fangs incline forward and tips are favourably positioned for strike
Snout kinesis in snakes is aided by what structure? Jaw mobility?
- mobility of prefrontal relative to skull roof
- elongation of the quadrates and pterygoids
True or false? Snakes have lost both temporal arches.
True
The compound bone of snakes is formed by what?
fusion of the articular and prearticular
What additional intervertebral articulations are seen in the snake to strengthen the vertebral column? Function?
- zygantra
- additional zygapophyses that interlock and add additional protection against twisting of vertebral column
What are pneumatized long bones in the birds?
bones of skeleton that contain air spaces and lack marrow, light for flight
How did birds reduce their weight considerably for flight?
- pneumatized bone of skeleton
- light bones in skull
- lack of teeth in beak
The upper beak of the bird meets the skull due to what flexible hinge?
craniofacial hinge
How do birds have cranial kinesis?
upper jaw is raised at the same time that the lower jaw is depressed
What allows for the head of the bird to rotate freely?
- the atlas has a notch on ventral surface of its posterior end that receives the dens of the axis
- peg like projections allow for free rotation
- birds can reach all areas of their body
What is the synsacrum of the bird?
fusion of some of the thoracic vertebrae with all the lumbar vertebrae
Which feathers attach to the pygostyle?
retrices (tail feathers)
Name three strong pectoral girdle bones of the bird. Function?
scapula, coracoids, clavicle prevent collapse of the chest cavity during wing beats
The pelvic girdle and synsacrum provide a high surface area for what?
muscle attachment
What gives the birds skeleton rigidity?
keel-shaped sternum
How would you be able to identify a bird that cannot fly?
a bird without a keel cannot fly
What is the process of ecdysis?
in snakes, they shed their old SKIN (not scales!) to replace it with newer skin
What is a shared similarity between birds and turtles?
both have no teeth
What are the roles of temporal fenestrae in crocodilians?
holes that allow for muscle attachment of the jaw
-allows muscles to pass through and connect to the other side of the skull
Match.
Amniotes, Archosaurs, Lepidosaurs, Sauropsids, Testudines
Overlapping scales, shelled egg with extraembryonic membranes, fenestra anterior to orbit, loss of fenestrae, beta keratin present and supratemporal bones small or absent
Lepidosaurs-overlapping scales
Amniotes-shelled egg with extraembryonic membranes
Archosaurs-fenestra anterior to orbit (Crocodilians and birds)
Testudines-loss of fenestrae (turtles)
Sauropsids-beta keratin present and supratemporal bones small or absent (lizards and snakes)
Match.
Turtles, Crocodiles, Birds, Snakes, Lizards
Compound bone, Furcula, Gastralia, Streptosyly, Plastron
Turtles-plastron Crocodiles-gastralia Birds-furcula Snakes-compound bone Lizards-streptostyly
Match.
Furcula, Gastralia, Synsacrum, Lateral fenestrae, Scutes
Opening which lightens lower jaw, support abdomen, fused coracoids and clavicles, fused thoracic and lumbar vertebrae, shell scales
Furcula-Fused coracoids and clavicles
Gastralia-supports abdomen
Synsacrum-fused thoracic and lumbar vertebrae
Lateral fenestrae-opening which lightens lower jaw
Scutes-shell scales
What is the role of the atlas in birds?
with dens, it allows head rotation
How many occipital condyles does a turtle have?
only one
The position of the nares on crocodilian allows what?
allows the animal to breath while being almost completely submerged in the water
Match for structure of lizards.
Coronoid process, retroarticular process, squamosal, quadrate
Site of muscle attachment, swings forward during streptostyly, site of muscle attachment, articulates with the quadrate
Coronoid process-site of muscle attachment
Retroarticular process-site of muscle attachment
Squamosal-articulates with the quadrate
Quadrate-swings forward during streptostyly
