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