Lab 6: Amniotes Flashcards
What small carnivorous dinosaurs did birds revolve from
Theropods
Reptiles, birds and mammals are collectively called….
Why?
Amniotes
-amniotic egg have a shell that retains water and can be laid in a dry place. Inside the shell of the amniotic egg are several extra-embryonic membranes that function in gas exchange, waste storage and the transfer of stored nutrients to the embryo.
Most distinctive specializations of turtles
-live in a box of bone (exoskeleton)
-toothless
-limbs lie inside their rib cage.
The entire turtle body Including the shell is covered in…..
Scales known as epidermal scutes
-scores are mooted and replaced by underlying scutes at regular intervals
-formed from keratinized epithelium: form a barrier to prevent water loss
-contain species specific pigmentation
The bony top shell of titles is called a
Carapace
Digits of amniotes have epidermal derivatives called
Claws
The carapace consists of fused plates of ________.
Also have parts of the ______ skeleton like the ribs and vertebrate fused to it
Dermal bone
Axial skeleton
Lower shell of turtle is known as
Consist of
Plastron
9 fused plates of dermal bone- 4 paired elements and one median unpaired element, anteriorly.
The carapace and plastron are connected Where
Laterally by a bridge of bone
The edge of turtle jaws are covered in……
A horny beak composed of heavily keratinized epidermis
-sharp cutting and piercing surface
The anterior nares of turtles leading to the …..
Internal nares or choanae
Eyes of turtles have both upper and lower ______ and a ______ membrane
Eyelids
Nictitaing membrane- translucent membrane can be drawn across to protect eye while still allowing the eye to be open to detect light and movement
How do you determine the sex of a turtle?
-Females are generally larger
-Vent (opening of cloaca) opens at or anterior to the end of the carapace in females
-Tails of male turtles are linger and wider and the vent opens caudal to the end of the carapace in order to accommodate the penis.
-front claws are same length to rear claws in females. Front claws are longer in males
-Plastron is convex in females but concave in males
Type of teeth in turtles
Edentate - no teeth
The choanae open on either side of the cranial end of the _____
Vomer
Secondary palate
In sea turtles, a shelf of bone that partially covers the primary palate. Formed by extension of the vomer and palatine bones.
Allows animals with a secondary palate to manipulate food in the mouth and breathe at the same time.
Vertebral column of turtle has same basic vertebral groups as necturus:
Cervical trunk sacral caudal
However, all but the cervical and caudal vertebrae are fused to the carapace (top shell)
How many cervical vertebrae do turtles have?
What is first one called, what does it do?
What is second one called?
8- give reptile a more distinct neck region
Atlas-Forms a ball and socket joint with the single occipital condyle of the skull to permit slight up and down movements of the head
Axis-specialized joint with atlas which permits side to side rotational movements of the head
Unique adaptation of cervical vertebrae in turtles
Can be withdrawn beneath the carapace by contraction of the complex and powerful neck musculature
Defence mechanism
Trunk vertebrae of turtles
10-fused dorsally with the bony plates of the carapace.
-Zygopophyses are poorly developed or absent
-each bear a pair of ribs
-no sternum in turtles
-ribs do not extend ventrally to enclose and protect the heart, lungs and viscera, or participate in moving air
Reptiles tend to have stronger limbs which bear more weight compared with amphibians, hence they have 2 or more _______ instead of 1
Sacral vertebrae
First sacral vertebrae in turtles
Has enlarged ribs which fuse to the ilia of the pelvic girdle
Orientation of pectoral girdle in turtles
Unique among vertebrates as it lies inside the rib cage between carapace and plastron.
Endoskeleton girdle of turtles parts
What do they join together to form?
3 prongs that form a tripod of bone which functions to join the forelimb to the axial skeleton and permits the animal to bear the weight of the head, neck and trunk on the limbs.
-dorsal prong is the Scapula
-acromion
-Coracoid
Glenoid cavity-articulates with the arm
Pectoral appendage of turtle parts?
What is the phalanges formula?
Humerus
Radius (medial)
Ulna (flattened)
Carpals (wrist)
Metacarpals (palm)
Phalanges (digits)
5 digits: 2-3-3-3-2
What type of muscles in turtles are greatly reduced due to the plastron?
What are these muscles used for?
Hypaxial - expansion and compression of the pleural-peritoneal cavity. Ventilated the lungs by contraction of hypaxial muscles
The external and internal oblique muscles of turtles have fused to from a single:
Oblique abdominis
-deposit of greenish coloured fat which lies beneath the skin
Beneath the oblique abdominis lies another thin hypaxial muscle layer, ____
Transverse abdominis
Do turtles have a rectus abdominis?
Nope
Sternomastoid
Thin, narrow strap of muscle which runs diagonally from the pectoral girdle to the side of the head.
-a branchiomeric muscle homologous to the Cucullaris
-acts to turn the head
Oomohyoid
Hypobranchial muscle that forms paired strips running longitudinally beneath the sternomastoid. Helps retract the head into the shell, open the mouth and lower flow of the mouth.
Retrahens capitis collique
Major muscles involved in pulling the head and neck into the shell.
Trachea
Lies ventral to the esophagus and appears as a whitish tube supported by cartilaginous rings.
-main pathway of air to the lungs
Air pathway in turtles
Trachea - right and left bronchi-lungs-alveoli (air pockets in lungs creating surface area of gas exchange)
Is cutaneous respiration possible in reptiles
No, need thought outer skin to reduce desiccation, therefore no cutaneous respiration
Cloaca in turtles is divided how?
Into 3 parts by small ridges in its wall
Copeodeum
The large intestine opens into the anterior chamber called the coprodeum.
Dorsal and lateral to the opening of the large intestine are the opening into the cloaca of the ____
Accessory bladders, oviducts (female), ductus deferens (males), and the urinary bladder
Empty into the cloaca known as the urodeum
Proctodeum
Most posterior chamber of the cloaca and is a short segment leading to the outside via the anus
Accessory bladder function
Store water by the female for setting the earth during nest digging. Are also accessory respiratory organs and are heavily vascular used for extracting oxygen from water.
Kidneys of reptiles are of what type?
Metanephric-drained by ureter, smaller, more nephrons, higher glomerular filtration rate, higher rate of tubular reabsorption.
Most reptiles and birds are uricotelic meaning what?
Exception?
Excrete nitrogenous wastes as Uric acid, a semi-solid white paste which is nearly insoluble in water. Uses very little water to do so.
Except fresh water turtles who excrete urea
Evolution of a penis obviates the need to return to water why?
Don’t need water to transfer gametes
Parts of Turtle penis
-corpora cavernous penis: blackish-grey erectile tissue
-Urethral groove: where spent travel
-Glans penis: heart shaped
Erectile tissue is ______ and becomes filled with ____ from the _____ during erections
Spongy
Blood
Internal iliac vein
In terms of reducing the overall weight of birds, these modifications have occurred
-loss of teeth and heavy jaws
-loss and fusion of bones
-hollowing, thinning and flattening of bones
-reduction in length of intestine, loss of bladder, regression of gonads in non-breeding season
-air spaces in homes and body cavity
To achieve the enormous amount of power required for flight, birds evolved the following:
-high body temperature and being homeotherms
-feathers that conserve heat
-rapid heart rate to increase circulation
-one way flow of air through lungs
-breathing movements synchronized with flight movements
-air sacs to permit internal cooling of the body
-diet consisting of high energy food with little indigestible material
Elongated beak consists of….
Upper and lower jaws encased in a horny sheath composed of heavily keratinized epidermis that replaces teeth
Only well-developed skin gland in birds
Uropygial Gland - secretes oily substance which bird gathers on the beak and spreads on the feathers of the wings and body. Oil served to waterproof the feathers and maintain physical structure
Skin of birds
-Loose and thin
-scales on legs and feet similar to reptile scales
Claws and beak are thought to be modified ….
Scales
Feathers function
Flight and heat insulation
Synsacrum
5th thoracic vertebrae, 3 lumbar vertebrae, 4 sacral vertebrae and first 6 caudal vertebrae are fused together to from synsacrum. Supports the pelvic girdle to withstand shock of landing.
Most of the vertebral ribs bear posteriorly projecting ________ in birds
Uncinate processes
-brace thorax and produce attachment sites for muscles that support the girdle
Do birds have a sternum?
Yes-flightless birds have a ratite sternum with a flattened ventral surface. The variants sternum in flying birds has a large keel (carina)-site of attachment of the large flight muscles that operate the wings
Pectoral girdle function in birds?
Parts of the girdle?
Attach the wing firmly to the body and to withstand the powerful force of the wing on the down stroke
-Sternum
-Scapula
-Clavicle (fused clavicle is furcula-wishbone)
Furcula function
Spring-like connection between the two shoulder girdles
The Coracoid, clavicle and scapula come together proximally in such a way that a hole, _______is formed
Foramen triosseum
To unfold the wing, the triceps contracts and the forearm is extended. The pulls the _______ taut and automatically extends the wrist
Patagial tendon
How many fused carpals form wrist in birds?
The metacarpals (2,3,4) have fused with several carpals to form the large, elongate _________
How many digits?
2, others have fused with metacarpals
Carpometacarpus
3
Pelvic girdle of birds is composed of what 3 bones
Which parts converge in a deep socket, the acetabulum which receives the head of the femur?
Ilium, ischium, pubis
Ilium and ischium and pubis
Patella
Knee joint in birds
Tibiotarsus
Tarsometatarsus
Fusion of the tibia and tarsal bones
Fusion of tarsal and metatarsal bones
Pectoralis in birds
Supracoracoideus in birds
Flight muscle producing the power down stroke
Beneath the pectoralis- passes through the foramen triosseum-elevates the wing and produced the recovery stroke
Tensor patagialis longus
Tensor patagialis brevis
Assists in tensing the patagium-the fold of skin extending from the upper arm to the forearm.
Assists in flexing and elevating the wing
Opens the wing with very little muscle bull or energy expenditure
Airs sacs in birds
Thin-walled sacs filled with air which extend between various organs and into certain bones. Not involved in respiratory gas exchange but instead create air spaces in the bones and body cavity to reduce the animals weight and cool the animal.
Respiratory system of birds is unlike other vertebrates in that it results in a ____________
One way flow of air through the lungs
-allows counter current system between inspired air and the blood flowing through the lungs.
Crop
Esophagus leads from the pharynx into a thin-walled bilobed sac - crop
Food is retained temporality here before passing to the stomach.
Food can be regurgitated from the crop to feed young.
Lining of crop is glandular that secretes a milky substance fed to the young
Birds which feed extensively on vegetative plant parts have elongate ______ that are used to hold volumes of plant material which is digested by symbiotic bacteria
Cacae
Do birds have urinary bladders?
No-temporary storage of urine occurs in the urodeum.
Reproductive organs of birds
Females are on left side only (less weight)
Males mostly lack a penis. Instead, sperm are passed to the female directly
Through the cloacae.
Reproductive structures of both sexes shrink to very small sized between mating seasons to reduce body weight
Reptilian integument
-reduction in glandular tissue
-horny epidermal scales in epidermis
-skin shows more than one generation of cells
-Dermal and epidermal pigments
-claws are integumentary structures
Avian integument
-feathers from epidermal layer: large contour feather, down feather, filoplume feather
-scales like reptiles on skin of legs
-bill is integumentary structure
Mammalian integument
-hair and glandular structures
Hair is not homologous with scales and feathers
Feathers, hair and glands are derivatives of which skin layer
Epidermis
Bony scales of fish and bony parts of turtle shell are from which skin layer
Dermis
Epidermal scale example
Feathers
Contour feathers
Most common type of feather found on the body surface, wings and tail. Most complex in structure consisting of a hollow shaft imbedded in the skin and the feather vane. Vane is made up of a solid shaft, or rachis from which barbs extend on either side. Barbs have tiny branches on either side called barbules. They have small hooks to interlock with other barbs. Allows feather surface to remain smooth and unbroken.
Remiges
Flight feathers attached to the posterior border of the wing.
-primary remiges: attached to hand bones
-secondary remiges: attached to the edge of the ulna.
Semiplumes
Small, white feathers intermediate between contour feathers and down feathers.
-beneath contour feathers
-soft texture with no interlocking barbs
-assist in trapping air for insulation.
Down
Feathers found in young chicks and adult birds underneath contour feathers.
-thermal insulation layer and abundant on waterfowl
Filoplumes
Slender, hair-like feathers found all over the body, adjacent to the base of other feathers. Each consists of a rachis with few barns near the tip.
-sensory in function-few nerve ending in the follicles which likely connect to pressure and vibration receptors.
Feather colour
Black and brown caused by Melanophores
Red and yellow by carotenoids (xanthophores)
White by air filled spaces
Hair is an ______ derivative
Epidermal
Cans be Definitive growth - certain length only than shed or angora growth-grows continuously and may never shed.
Vibrissae
Long stiff hairs which function as tactile receptors
Guard hairs
Protective function and there are 3 types:
-spines: protect from predators
-bristles: angora growth
-awns: definitive growth
Underhairs
Primarily function as insulation
-wool: curly soft angora under hair
-fur: under hair with definitive growth
True horns
Permanent, unbranched. Composed of epidermally-derived sheath which covers an inner body core formed from the frontal bone. Grow from their base throughout life and never shed, although they may break. May be on males or males and females
Pronghorns
Similar to true horns except that the epidermal sheath had a simple small anterior projection. Shed annually.
Antlers
Covered by a layer of skin (velvet) which is shed to reveal the fully developed antler which is entirely a bony structure, an extension of the frontal bone. They are branched and she’s annually
Giraffe horns
Pair of permanent short, unbranched bony processes covered with skin and hair. The bony processes are situated over the sutures between the parietal and frontal bones and are fused to the skull.
Rhinoceros horns
Solid mass of hardened epidermal cells which resemble thick hairs cemented together. The skin bearing the horn is situated over the fused nasal bones. Used as offensive and defensive weapons and in courtship rituals.
The digits of most mammals, birds and reptiles are protected by sheaths of
keratinized epidermis composed of two scale-like keratin plates:
-upper plate=unguis
-subunguis
Most primitive type of digital keratinization is the _______
Claw
Unguis is well developed and hard more so than the subunguis and is covered longitudinally and transversely to enclose the subunguis.
A _____ is a modified claw
Nail- covers the dorsal surface of the end of the phalanx of the digit.
The unguis is broad and flattened.
Subunguis is reduced to a remnant lying under the tip of the nail.
Hoof
Unguis Forbes almost completely around the end of the digit and enclosed the subunguis within it.
