Reptiles and Birds Flashcards
1
Q
How many fenestra do anapsids have?
A
0
2
Q
How many fenestra do diapsids have?
A
2
3
Q
Why are turtles hard to place on a phylogenetic tree?
A
They have no fenestra (anapsids), so they would be placed before the divergence of synapsids and sauropsids, if not for other evidence
4
Q
What are the possible phylogenetic hypotheses on the placement of turtles?
A
- Diverged after split of Amniota as a sister taxon to Diapsida
- Diverged after Diapsida as a sister taxon to Sauria
- Diverged after split of Sauria into Lepidosauria and Archosauria, as a sister taxon to Lepidosauria
- Diverged after split of Sauria into Lepidosauria and Archosauria, as a sister taxon to Archosauria
5
Q
Where are turtles placed in the amniote phylogenetic tree based on our current hypothesis?
A
After the divergence of lepidosaurs and archosaurs, as a sister taxon to Archosauria
6
Q
What are some fossil pieces of evidence that support hypothesis 4 seen in stem turtles?
A
They have an upper temporal fenestra, and the development of a carapace, and plastron (which gastralia fused into). Gastralia are seen in Archosauria
7
Q
Although turtles are diapsids, why do they have no temporal fenestra?
A
Temporal emargination caused the loss of fenestrae
8
Q
Why might it be important for turtles to separate locomotion and lung ventilation, like crocodiles?
A
Lie-in-wait predation strategy requires little to no movement, and they can’t use buccal pumping due to their lack of gills
9
Q
How are members of Lepidosauria distinguished from each other (Rhynchocephalia, Serpentes, and “lizards”)?
A
The position and/or absence of their temporal bars
10
Q
What is the sister taxon to Squamata?
A
Rhynchocephalia (Tuataras)
11
Q
List the synapomorphies of Lepidosauria
A
Keratinous overlapping scales
Transverse cloacal opening
Autotomy planes in caudal vertebrae and muscles
12
Q
What dermal layer are scales made of? What biological mechanism determines its patterning?
A
Ectoderm; molecular pre-patterning by activators and inhibitors
13
Q
What three characteristics of scales are used to determine locomotive ability?
A
Organization, shape, and overlap tell us about the locomotive strategy
14
Q
Transverse vs. sagittal
A
Transverse goes across the body (lateral to lateral), while sagittal goes up and down the body (cranial to caudal)
15
Q
What mechanism may be regulating autotomy planes?
A
HOX genes
16
Q
True/False? The location of an autotomy plane on the vertebrae is the same for all lepidosaurs
A
False. Varies by species
17
Q
Why are autotomy planes useful in studying lepidosaur development?
A
They are well-preserved in the fossil record, as they are seen in the vertebrae
18
Q
How do lepidosaurs drop their tails without dying of blood loss?
A
Segmented muscular bundles prevent bleeding by restricting blood flow to that autotomy plane
19
Q
What is a unique feature of tuatarans?
A
They have no ear openings and have a pineal eye
20
Q
List the synapomorphies of Rhynchocephalia
A
Lower temporal bar re-evolved
21
Q
What can we infer about the skull structure of squamates in relation to the synapomorphy of Rhynchocephalia?
A
They lack the lower temporal bar
22
Q
List the synapomorphies of Squamata
A
Hemipenes
23
Q
What is a hemipene?
A
A 2-headed penis that squamates have that function independently of each other
24
Q
A phylogenetic tree based solely on morphology has what trends?
A
It tends to be polyphyletic (skinks), and some groups cannot fit into clades
25
A phylogenetic tree based solely on molecular evidence has what trends?
Tends to be more monophyletic
26
A phylogenetic tree based on morphology and molecular evidence has what trends?
Both monophyletic and polyphyletic, but more specific than just molecular evidence, strongest argument
27
List the synapomorphies of Serpentes
Upper temporal bar lost
28
The loss of the lower and upper temporal bars allow for what in snakes?
Cranial kinesis
29
What is cranial kinesis?
The ability of the components of the skull and jaw to move independently, especially when eating
30
What is jaw walking?
The independent movement of the left and right sides of the skull and jaw to move when eating large prey
31
What is another name for the upper temporal bar?
The jugal
32
The jugal makes up which important bones in the skull?
The upper and lower bars
33
What are some features of Dibamidae? What do they resemble?
Absence of ear holes
Rudiments of the hindlimbs
Highly fused head
Fossorial locomotion
Resemble caecilians (convergence!)
34
What is a synapomorphy of Gekkota?
Toe scansors
35
What is unique about Pygopodidae?
Limbless, but have pads and flaps where the pelvic and pectoral girdles would be
36
Fossilized gecko specimens show what evidence?
Toe pads
37
What organisms does Scincoidea include?
Skinks
38
What squamate clade is the most speciose?
Scincoidea
39
What is the main difference between Lacertidae and Teiidae?
They vary geographically (Lacertidae is old world, Teiidae is new world)
40
Where do mosasaurs fit into the Sauria phylogeny?
Sister taxon to Serpentes (under Squamata)
41
What evidence suggests mosasaur's positioning on the phylogenetic tree?
They have a forked tongue and similar palatal morphology to snakes
42
Helodermatidae
Gila monsters, extremely venomous, slice flesh which teeth and let venom seep into wound
43
Varanidae
Monitor lizards, semi-aquatic
44
What is the main difference between Agamidae and Phrynosomatidae?
Geography. Agamidae is old world, Phrynosomatidae is new world
45
Chamaeleonidae
Chameleons. Zygodactyls, arboreal, protrusible tongues
46
Dactyloidae
Anoles. Show extreme convergent evolution due to biogeographical separation
47
Iguanidae
Iguanas
48
What are the three sensory systems in Squamata?
Vomeronasal, nasal olfactory, and gustation
49
Describe the olfactory system in squamates
Large surface area in the nasal cavities allows for chemosensation
50
The vomeronasal system in squamates connects which structures?
Olfactory surface area and palate
51
Describe the gustatory system in squamates
Taste buds on lingual and oral surfaces
52
What are the two predatory modes seen in squamates?
Sit and wait and active foraging
53
What impacts predation mode?
Reliance on chemosensation
54
Sit and wait predators rely on:
Eyesight
55
Active foraging predators rely on:
Chemosensation
56
How do active foragers use chemosensation to hunt?
Able to use all three systems to determine strength of signals for directional sensing
57
What is usually associated with sit and wait predatory styles?
Cranial ornamentation, crypsis, and territoriality
58
What are the defense mechanisms seen in Squamates?
Autotomy, crypsis, venom, and deterrence
59
Describe autotomy
The loss of the tail along an autotomy plane. Its regeneration depends on the diet of the organism
60
Are squamates the only organisms that use autotomy?
No. In some cases, fish use this tactic too, with their scales
61
What is crypsis?
Blending in with the environment
62
Provide an example of an organism that uses deterrence
Horned lizard (Phrynosomatidae)
63
Explain how Phrynosomatidae uses deterrence
There is a lot of venous drainage behind the eye. When threatened, muscles squeeze these veins, which builds pressure in the head until they rupture and squirt blood onto the threat. Blood does not chemically differ from circulatory blood, so no other chemicals but the blood itself is used
64
What is important about venom glands in terms of development? How do we know?
Derived from salivary glands; they contain pancreatic enzymes
65
Why is venom important to study? Provide an example
Can be used to derive drugs. For example, the GLP-1 protein found in some venom is used in Ozempic
66
What is a gular fan?
A fan located on the throat of an anole used in communication in conjunction with head bobs
67
What kind of gular fan would be used in a very green, leafy area?
Red, for high contrast
68
What kind of gular fan would be used in a place with lots of light?
A translucent flap, that refracts light
69
Describe gular fans in the context of mating rituals. What colours mean which?
Orange: establishes large territory and roster of females
Blue: establishes small territory
Yellow: sneaker male, steals females from blue and orange
70
What is the tradeoff between gular fans and crypsis?
Bright fans may attract predators
71
Lizard dialects
Vary depending on species, using the same methods but in different ways (more head bobs than another species, for example)
72
The development of different lizard dialects may lead to:
Speciation by reproductive isolation
73
Describe what happens when only juvenile skinks are present in a basking setting
All get lots of time to bask
74
Describe what happens when only skinks within a family are present in a basking setting
All get lots of time to bask
75
Describe what happens when dominant and subordinate skinks are present in a basking setting
Dominant skinks get lots of time basking, while subordinate skinks spend most of their time in shade because they aren't permitted access by the dominant skinks
76
Describe how communication between skinks impacts fitness
Subordinate skinks have reduced fitness because they do not achieve the level of sunlight they need for proper thermoregulation. Dominant skinks have increased fitness for the opposite reason
77
True/False? Lizards can be viviparous
True
78
What is the difference between lizard placenta and placental placenta?
Placentals have much more physical connection to their mothers, while lizards don't have as much
79
What are the benefits of being a viviparous lizard?
Eggs don't have to be warmed, and movement isn't limited by a nest
80
What are the disadvantages of viviparity in lizards?
More parental care (energetically costly), which leads to smaller clutch sizes, and locomotion and communication are limited
81
What are the pressures that might have caused parthenogenesis to evolve?
No energy is spent on reproduction, and extreme temperature determines sex (usually favours females, which can undergo parthenogenesis again if need be)
82
Describe how you can get a fertilized egg through parthenogenesis
In extreme heat conditions, 1/3 polar bodies created by meiosis fuses with the oocyte, causing a fertilized egg
83
Which sex determination strategy do most lizards use? What clades are the exceptions?
Genetic; Gekkonidae, Scincidae, Chamaeleonidae
84
What is unique about geckos in terms of sexual reproduction?
They have similar sex chromosome complexes to Monotremes (can use XY or ZW)
85
An organism with ZZ sex chomosomes is _________
Male
86
An organism with ZW chromosomes is ________
Female
87
True/False? Serpentes uses both genetic and environmental sex determination
False. They use genetic sex determination
88
What sex determination method do Testudines use?
Environmental sex determination
89
How do homeothermic ectotherms regulate body temperature? How does this differ from endotherms?
Use behaviour rather than metabolism
90
Describe the behaviour of a homeothermic ectotherm lizard on a warm day
They actively seek out heat from the environment and bask with most of their body's surface area facing the sun. They are active once within their optimal temp range
91
Describe the behaviour of a homeothermic ectotherm lizard on a hot day
Utilize convective cooling from the environment (like wind) and reduce surface area exposed to the sun either by staying in the shade or facing directly towards the heat source
92
Describe the behaviour of a homeothermic ectotherm lizard on an extremely hot day
They avoid activity all together and seek shelter
93
How does activity level change in homeothermic ectotherms as environmental temperature increases?
No activity if cold, optimal range has most activity and it decreases as heat increases from there
94
In what conditions do homeothermic ectotherms and endotherms converge in terms of energy conservation
In extreme heat
95
What is a facultative endotherm?
Can occasionally use metabolism to generate body heat
96
What function does facultative endothermy serve in lizards?
Has links to sex determination in species that rely on the environment
97
Allopatric speciation
Speciation occurs due to physical barriers, like geography
98
Sympatric speciation
Speciation occurs due to niches within one geographical area
99
Provide an example of sympatric speciation
The *Ameiva* genera, that speciated due to light availability differences in a forest
100
How does weight impact sympatric speciation in *Ameiva*?
Species of lesser weight tend to spend more time in the unshaded areas, while greater weight species tend to spend more time in the inner forest. Species in the middle of this weight distribution spend time at the edge of the forest
101
Why do smaller *Ameiva* species spend more time in unshaded areas?
They gain and dissipate heat a lot faster and have a higher metabolism, so they can dart in and out of the sun without overheating
102
Why do larger *Ameiva* species spend more time in shaded areas?
They dissipate heat much slower, so are at risk of overheating in unshaded areas. They can bask, then spend much more time in the shade than smaller species
103
Where would juveniles of larger *Ameiva* species tend to hang out? What is this an example of?
Spend more time in unshaded areas because they dissipate heat faster, but as they grow they move towards the inner forest; niche partitioning
104
What is an ecomorph?
Two species with different phylogenetic origins that share a particular niche
105
The presence of an ecomorph suggests what for the niche the species share?
Convergence
106
What are the three key attributes of snake locomotion?
1. Epaxial and hypaxial musculature and connective tissue
2. Vertebral interactions
3. Relative position of the ribs to vertebrae
107
What do tendons connect?
Muscles to muscles
108
What modifications to the vertebrae do snakes have? How do they aid in locomotion?
Extra zygapophyses (zygosphenes and zygantra), which increase the stability of the vertebrae and disallow independent motion of each vertebra
109
Where are the ribs located in snakes? What does this allow for?
Attached to the vertebrae and present all along the body excluding the tail. They allow for the different modes of locomotion in snakes (rectilinear, gliding, concertina, etc)
110
Why do snakes have a loss of limbs?
Reduced HOX gene signaling in the limb buds
111
How does girdle position relate to limb reduction and movement?
The farther the girdles, the more reduced the limbs, the more lateral undulation
112
Why are snakes seen as the "reverse transition to land"?
Because in the transition to land, limbs were gained, but snakes lost their limbs
113
What was the primary environmental pressure for the loss of limbs and scale pattern on the ventral surface?
Substrate interactions
114
Describe lateral undulation
Hypaxial muscles within a segment on one side of the body work together to contract while the muscles of the same segment on the other side of the body are relaxed. These segments alternate throughout the body at any given time (first segment, left contracted. Second segment, right contracted. Etc)
115
What is an extreme of lateral undulation?
Gliding
116
Describe gliding locomotion (snakes)
The ribs move with the hypaxial musculature to flatten, creating a "wing" out of the snake's entire body
117
Describe sidewinding
Snake uses extra epaxial musculature to "skip" sideways along with the hypaxial movements of undulation
118
In what climates is sidewinding used? Why?
Hot climates (deserts) with loose substrate; it reduces surface area in contact with the hot sand, which helps in thermoregulation
119
Which snake locomotion strategy is the fastest but most energy consuming?
Sidewinding
120
Describe rectilinear motion
Most hypaxial muscles contract and stretch in segments along the ventral surface used in a caterpillar-like movement
121
What kind of ventral scales does a sidewinder require?
Porous to reduce friction and surface area exposed to substrate
122
What kind of ventral scales does a rectilinear snake require?
Thick dermis that can withstand high abrasion
123
What is the tradeoff with rectilinear motion?
Slow, but conserves energy
124
What kind of snake will use rectilinear motion?
Very venomous snakes that don't need to chase down prey
125
Describe concertina motion
Snake creates anchor points by pinching its substrate between its segments using hypaxial muscles. Used to climb. Epaxial muscles used to extend the neck after anchoring to move to the next anchor point
126
What is a pit organ? Which nerve innervates it?
An organ snakes use located near their mouth and eyes to sense thermal traces. Innervated by the cranial nerve that also attaches to the eye
127
How do snakes use their pit organs?
Use them in conjunction with their eyes
128
If snakes could only use their pit organ and eye contralaterally (one left and one right), what would happen? What does this imply?
Contradiction in their ability to pinpoint the location of prey; rely on both organs on both sides altogether
129
What do snakes use in their predation strategies?
Venom and constriction
130
What kind of motion do constrictors use to hold prey?
Concertina
131
Why do constrictors target mammals?
Mammals use diaphragmatic breathing, which is easy to stop if the prey item is squeezed so their lungs can't expand
132
What evidence suggests venom glands are derived from salivary glands? Are they homologous or analogous?
They have proteins that are similar to the enzymes (pancreatic-like) found in salivary glands. They are homologous structures
133
Which tissues have the potential to be venom glands in snakes? What does this show?
Venom gland, rictal, infralabial, and potentially the supralingual; convergence
134
Describe the head musculature in boas. Why?
Superficial and deep masseter; they are nonvenomous so don't need specialized muscles
135
Describe the head musculature in vipers. Why?
Superficial and deep masseter, with a specialized deep masseter looping around the superficial; used to squeeze venom out of the venom gland
136
Describe the head musculature in early snakes. Why?
Superficial and deep masseter, but venom gland is medial to superficial; muscles "stimulate" the venom gland rather than "squeeze" it
137
Describe how teeth, fangs, and venom glands have the same developmental origin
Form from the same developmental lamina as venom glands consisting of neural crest plus mesenchyme
138
Compare boid and viperid vertebrae
Boid: less lateral protrusion to allow for more lateral flexibility (needed to constrict prey)
Viperid: more lateral and dorso-ventral ornamentation to allow for more muscle attachment (faster striking)
139
What predation modality would we see in constrictors more often?
Active foraging
140
What predation modality would we see in venomous snakes more often?
Sit and wait, use crypsis
141
Describe cranial kinesis. What is this called?
Jaw is able to unhinge to allow consumption of large prey items; "jaw-walking"
142
What are the defense mechanisms snakes use?
Caudal lure, spitting venom, venomous resistance, and aposematism
143
What is aposematism?
Mimicry (non-venomous looks like venomous)
144
Aposematism is likely a result of:
Convergent evolution
145
Why do snakes have indeterminate growth?
Their low metabolisms allow them to put much more energy into producing new tissue than mammals, which use most of their energy just maintaining homeostasis
146
In terms of thermoregulation, snakes are:
Homeothermic ectotherms
147
Like other squamates, snakes can sometimes be ____________ endotherms
Facultative
148
When do squamates tend to use facultative endothermy?
When incubating eggs
149
Why is studying Titanoboa important?
Researchers able to deduct the environment in which it lived by studying the vertebrae and correlating its size to body temperature, which suggests it lived in cooler places due to its massive size
150
List the synapomorphies of Testudines
Ventral osteoderms fused together (plastron)
Axial skeleton fused to osteoderms (carapace)
Carapace and plastron fuse together to form the shell
Shell is covered with keratinous plates superficially (scutes)
Pectoral and pelvic limb girdles within the shell
Loss of teeth, have keratinous beak
151
Describe the placement of scutes relative to the fused bones underneath
Scutes are larger than the individual bones, so one scute covers multiple bones in order to distribute applied weight more evenly
152
What kind of organ are scutes?
Ectodermal
153
Which came first? The carapace or the plastron?
Plastron developed first
154
What was the function of the plastron in ancestral turtles?
Aquatic ballast
155
Gastralia are homologous to:
The plastron
156
Why do we believe the plastron developed from the gastralia?
They share the same organizational pattern
157
Why do turtles need an aquatic ballast?
They don't have a swim bladder like fish
158
Compare the amniote pectoral girdle to the testudine pectoral girdle
Amniotes:
- protrude dorsal to ribs
- muscle plate follows the curve of the rib
Testudines:
- internal to the shell (ventral to ribs)
- muscle plate follows the curve of the rib, then wraps around the scapula (change in muscle connectivity)
159
Why did turtles evolve their girdles the way they did?
They needed to be modified in order to accommodate the shell
160
Describe the differences and similarities between archosaurian and testudine ectodermal organ patterning in relation to teeth
The same in every way except turtles lack the ectodermal patterning pathways specific to teeth
161
What is the main difference between Cryptodira and Pleurodira?
Cryptodira folds its neck into a dorsoventral "c" shape, while Pleurodira folds its neck into a lateral "c" shape
162
What are the challenges of living within the shell?
Ventilation
Locomotion
Feeding
Muscular insertion and origins
Thermoregulation (linked to sex determination)
163
Describe the differences in the pelvic girdles between cryptodires and pleurodires
Cryptodires: pelvic girdle not fused with the shell
Pleurodires: pelvic girdle fused with shell
164
What were the results from a multi-varied analysis on turtle musculature between Cryptodira locomotion and Pleurodira locomotion?
The way in which the muscles worked was highly differentiated between Cryptodira and Pleurodira (different muscular insertions and origins), but they converged on muscle performance and efficiency (working together) in locomotion (walking muscles used similarly, swimming muscles used similarly)
165
Describe diagonal sequence locomotion
Left front foot and right back foot step forward together and vice versa
166
Describe lateral sequence locomotion. What is this type of locomotion seen in?
Left side works together, right side works together; big tortoises (Testudinidae)
167
Describe synchronous locomotion. What is this type of locomotion seen in?
Front flippers work together synchronously; sea turtles (Cheloniidae)
168
What kind of locomotion would you expect to see in a semi-aquatic (pond) turtle?
Both diagonal and synchronous
169
Contrast diaphragmatic breathing and Testudines breathing
Testudines: active inhale and exhale
Diaphragmatic: active inhale, passive exhale
170
Describe inspiration in turtles
Pectoral girdle is pulled cranially, pelvic girdle pulled caudally, which causes negative pressure within the gut, which then causes negative pressure within the lung
171
Describe exhalation in turtles
Pectoral girdle pushed caudally, pelvic girdle pushed cranially which causes positive pressure in the gut, which then causes positive pressure on the lungs
172
What is an important part of turtle respiration?
The gut
173
The snapping mechanism of a turtle's jaw is enabled by this component:
Otic capsule (part of the jaw joint)
174
Describe the sequence of selection pressures on turtles that resulted in the development of the otic capsule
The shell put pressure on the neck (needed increased mobility), which put pressure on the skull (mobility requires emargination), which then put pressure on the existing jaw structure (development of a new joint)
175
What is green fat?
Turtle homologue to brown fat in mammals
176
What thermoregulatory strategy do turtles use?
Homeothermic ectothermy
177
Why are turtles spending less time in the water, even at night?
The water is getting too hot for them during the day, then it retains that heat at night, so they don't go back in
178
Why is climate change an issue for Testudines?
They use environmental sex determination
179
What is the muscular ridge?
It is the shunt in Testudines that separates deoxygenated blood from oxygenated blood when the ventricle contracts
180
Describe what happens in the contraction of the atria in turtles
Atrioventricular valves are open, allowing oxygenated blood into the left side of the ventricle and deoxygenated blood into the right, separated by the intraventricular canal
181
Describe what happens in the contraction of the ventricle in turtles when the muscular ridge is contracted
Atrioventricular valves are closed and the muscular ridge is contracted, separating oxygenated blood and deoxygenated blood. Oxygenated blood goes to the right and left aorta, deoxygenated blood goes to the pulmonary artery
182
What is the advantage of having the intraventricular shunt?
Used for lower metabolism to allow for increased blood oxygen efficiency by reducing blood flow to the lungs when not in use (swimming). Also used to increase systemic blood flow when basking to warm up faster
183
The intraventricular shunt in turtles is convergent to what in crocodylians?
Inter-aortal sunt (Foramen of Panizza)
184
Explain testudine migration
They are born on an island east of Brazil and migrate west for most of their lives, until they're ready to reproduce, then they swim back to the same beach they were born at and lay their eggs there
185
What are the cues used by sea turtles in their migration back to the island they were born at?
Geomagnetic imprinting, light (direction and phase of the moon), and wave directionality (underwater currents act like highways)
186
How is turtle migration biology applied to ocean research collection?
Robots were developed to use the same cues to navigate the ocean
187
Describe type Ia sex determinism in turtles
Low temp: male
High temp: female
188
Describe type II sex determinism in turtles
Extreme temps: female
intermediate temps: male
189
What are the consequences of having mostly environmental sex determination in a climatically unstable environment?
- more of one sex than the other
- impacts their behaviour
- eggs need to be incubated at a specific temperature to conserved the bottle-necked sex
190
Describe the vulnerable hatchlings experiment
Hatchlings were put on a small island and exposed to various levels of white light and moonlight exposure to see what impacted their movement to the ocean
191
What was seen in the white light vs moon night treatment?
Most turtles moved towards the white light, but some were rescued by the moon and moved towards the ocean
192
What was seen in the weak white light vs moon night treatment?
Most turtles moved towards the white light, but some were rescued by the moon and moved towards the ocean
193
What was seen in the white light vs moonless night treatment?
Almost all turtles moved towards the white light
194
What was seen in the weak white light vs moonless night treatment?
Almost all turtles moved towards the white light
195
In the vulnerable hatchlings experiment, what was the difference between white light and weak white light?
No difference
196
In the vulnerable hatchlings experiment, what was the difference between moon night and moonless night?
Some hatchlings were rescued by the presence of the moon, whereas on moonless nights, none made it to the ocean
197
How can the vulnerable hatchlings experiment be applied to their conservation?
Coastal cities may impact where the hatchlings are attracted to, which negatively impacts them by attracting them away from the water
198
List the synapomorphies of Archosauria
Antorbital fenestra
Mandibular fenestra
Thecodont teeth (how they use the teeth)
Double row of osteoderms along vertebral column
Fourth trochanter on the femur
199
How many fenestrae do archosaurs have in total?
4
200
Osteoderms in general would be a(n) ___________ of Archosauria
Apomorphy
201
What are the hypotheses for the development of the mandibular and antorbital fenestrae?
Extra room for muscles or to make the skull lighter (sinuses)
202
How does the development of the 2 extra fenestrae assist birds?
Assists in the evolution of flight (lighter head if they were sinuses and not for muscle attachment)
203
What are thecodont teeth?
Teeth heavily rooted in the jaw
204
What is the shape of an early archosaur's upper jaw? Why?
Hooked at the rostral end; helps to prevent prey escape
205
What allows for the double row of osteoderms seen in archosaurs?
HOX gene expression
206
A heavily protruding fourth trochanter indicates:
Locomotion is more reliant on the tail
207
What does the fourth trochanter serve as?
A muscle attachment site for the main undulatory tail muscle
208
What is implied about the reduced fourth trochanter in avians?
They rely less on their tail for locomotion
209
Why is the majority of muscle strain on the fourth trochanter?
The muscle that attaches to this point is very reliant on this process, and the organism that uses this muscle is very reliant on the muscle
210
True/False? Archosauria includes the dinosaurs
True
211
What are the non-avian dinosaurs?
Everything except Neornithes
212
What are the avian dinosaus?
Neornithes
213
The faveoli in crocodylian ventilation are analogous to:
Lamellae in the gills of fish
214
What type of ventilation do crocodylians have?
Cuirassal ventilation
215
What type of ventilation do avians have?
Unidirectional ventilation
216
What is the general change in the structure of the ventilation from crocodylians to avians?
Increased rigidity of respiratory organs
217
True/False? Much like testudine ventilation, crocodylians actively exhale and inhale
True
218
Describe the difference in the relative position of testudine ventilation structures versus crocodylian ventilation structures
Turtles: dorso-ventral
Crocodylians: Cranio-caudal
219
Because turtles respiratory structures are dorso-ventral, what force are they more impacted by than crocodylians?
Gravity
220
Explain inhalation in crocodylians
Negative pressure in the lung is caused by contraction of the diaphragmatic muscles
221
Explain exhalation in crocodylians
Forced contraction of the gastralial muscles, which allows for the air in the lungs to be exhaled. Pulls the lungs cranially to force air out
222
How many of cycles of respiration are needed to exhale a single molecule of O2 in birds?
2
223
Describe inhalation in birds
Negative pressure draws oxygenated air into the posterior air sacs. At the same time, negative pressure brings deoxygenated air from the lungs into the anterior air sacs
224
Describe exhalation in birds
Positive pressure pushes oxygenated air from the posterior air sacs into the lungs. At the same time, positive pressure pushes deoxygenated air from the anterior air sacs out
225
Is the unidirectional ventilation system efficient?
Very efficient, as there is no anatomical deadspace as there is in humans (cannot breathe out all of the air in our lungs)
226
Why do birds need such an efficient ventilation system?
Needed for flying, as this is very oxygen-dependent
227
What is the name of the shunt in crocodylians?
Inter-aortal shunt (foramen of Panizza)
228
Describe typical blood flow through a crocodylian heart
Pressure in the systemic circuit (left ventricle) is typically greater than in the pulmonary circuit (right ventricle), causing oxygenated blood to flow from the right aorta through the foramen of Panizza into the left aorta. Small amount of deoxy blood mixing in left aorta
229
Describe blood flow through a crocodylian heart when submerged or basking
Basking: expanded capillaries reduce systemic pressure, so more deoxygenated blood is able to flow through the left aorta along with some oxygenated blood. Blood volume is increased in the systemic circuit to heat up faster
Submerged: blood is shunted away from the pulmonary circuit to increase oxygen efficiency when lungs cannot be used
230
What happens to the foramen of Panizza when the crocodylian is active? Inactive?
Open; closed
231
Why do crocodylians need their inter-aortal shunt?
They are homeothermic ectotherms, so already have a low metabolism. On top of that, they are sit-and-wait predators, so they need to be able to shunt so they don't have to breathe as often
232
What are the differences between the therian circulatory system and the avian circulatory system?
Therian is left systemic artery, avian is right systemic artery
233
What are the similarities between the therian circulatory system and the avian circulatory system?
Everything except their right-left inversion
234
Why do therians have a right systemic artery and birds a left?
No specific reason, the selection pressures kind of just worked out that way
235
Why do therians and avians have such similar circulatory systems?
Both homeothermic endotherms (convergence on circulatory system = most efficiency (no shunts))
236
What are the clades in Crocodylia?
Crocodylidae, Gavialidae, Alligatoridae
237
How to tell the difference between gators and crocodiles?
Gators have a U-shaped snout, their top teeth cover their bottom teeth. Crocs have a V-shaped snout, top and bottom teeth both jut out
238
What is a gavial's snout modified for?
Eating fish
239
What do ancient crocodylians show on their teeth
Wear (potentially from mastication)
240
Why do crocodylians not have distinct synapomorphies between each clade?
Adaptive radiation and fast evolution of some traits caused a lot of convergent evolution
241
What two things, when considered alone, do not determine evolutionary potential?
Morphology and molecular evidence
242
Provide three examples of "living fossils"
Coelacanth, tuatara, and crocodylians
243
Why do the "living fossil" species not entirely provide their evolutionary potential/background?
They are still currently evolving and diverged in their own way from their ancestors
244
Compare the difference between crurotarsal ankles and mesotarsal ankles. What clade shows each?
Crurotarsal: Calcaneus and astragalus not fused, so the ankle joint is between them, allows for more rotational freedom; Crocodylia
Mesotarsal: Calcaneus and astragalus are fused, so the joint is distal to them; Aves
245
Sprawling locomotion in crocodylians
Low energy, uses lateral undulation
246
Erect locomotion in crocodylians
High energy, but usually faster. May walk or gallop
247
Are crocodylian's girdles efficient?
Yes! They allow for both a sprawling and erect posture
248
The secondary palate in crocodylians allows for:
Breathing while the rest of the body is submerged, which is important for their predation strategy
249
What predation strategy do crocodylians have?
Sit and wait
250
What are the bones of the crocodylian palate?
Premaxilla, maxilla, palatine (secondary bony palate)
251
The evolution of the secondary palate in crocodylians is convergent with:
Mammals
252
Can crocodylians masticate?
No, they must swallow their prey whole, so break up their prey by death-rolling
253
What are the two types of crocodylian vocalizations? What are they used for?
Bellowing and subsonic vibrations; courtship or a threat display
254
What were the osteoderms seen on the dorsal side of crocodylians selected for?
Shape + size selected for most vibrations possible in courtship displays (more vibrations = better fitness)
255
What is a type 1 survivorship curve? Provide an example
Offspring have high survivability until late life; elephants
256
What is a type 2 survivorship curve? Provide an example
Constant decrease in survivability over time; birds
257
What is a type 3 survivorship curve? Provide an example
Low survivability in early life until maturity; tortoises, sea turtles, crocodylians
258
What variable has the greatest effect on crocodylian sex ratio?
Temperature changes
259
How does crocodylian nest temperature change between 4.5°C and 8.5°C temperature increase?
Nest temperature increases with ambient temperature, where an 8.5°C increase has a greater impact
260
How does crocodylian sex ratio change between 4.5°C and 8.5°C temperature increase?
In 4.5°C, we see a rapid increase to almost all males in the population. In 8.5°C, we see the same, except a sharp change in the sex ratio now favouring females over males once a certain temperature is reached
261
How does crocodylian sex ratio change between more southern sites vs. more northern sites?
Same trend, but northern sites see an increase in the male vs female ratio a little later due to the temperature difference
262
Below 31.5°C and above 34.5°C, what sex is most common in crocodylians?
Female
263
Between 32.5°C - 33.5°C, what sex is most common in crocodylians?
Male
264
Based on the environmental sex determination temperatures seen in crocodylians, what type do they have?
Type II (females at extreme temps, males at intermediate temps)
265
What is significant about the Galapagos finches vs. the mainland finches?
The Galapagos finches are very very diverse due to adaptive radiation, but mainland finches don't have as much diversity despite having the same amount of time to evolve and fill niches
266
What are the three big contributors to adaptive radiation in birds?
Their beak shape, habitat, and diet
267
Paleognathae
Possess an immobile palate, where the vomer and palatine are highly associated and the joint between the palatine and pterygoid does not move
268
Neognathae
Possess a mobile palate, where the vomer is reduced and the joint between the palatine and pterygoid is moveable
269
The moveable joint in Neognathae allows for:
Cranial kinesis
270
Which directions can the upper beak move in Neognathae?
Rostrally and caudally, as well as dorsally and ventrally
271
What does cranial kinesis in Neognathae allow for?
The filling of diverse niches (adaptive radiation)
272
What is the K-Pg boundary?
Meteor impact event
273
What was Galloanserae?
Primitive birds that had a neognathan palate, but they retained some primitive skull features
274
When did Neornithes rapidly diversify? Why?
After the K-Pg boundary; many ecological niches were left vacant due to the meteor impact that killed the dinosaurs, allowing Neornithes to fill those gaps and become super diverse
275
When did Galloanserae diversify?
Before the K-Pg boundary
276
What are the clades within Paleognathae?
Tinamidae (Tinamous), Rheidae (Rheas), Struthionidae (Ostriches), Apterygidae (Kiwis), and Casuariidae (Cassowaries, Emus)
277
When did Paleognathae diversify?
After splitting from Neognathae
278
Describe the Ratite tree before the discovery of ancient DNA in relation to the Moa
Monophyletic: The Moa was grouped with other large ratites due to their similar morphology
279
Describe the Ratite tree after the discovery of ancient DNA in relation to the Moa. What does this show?
Paraphyletic: The Moa is the sister taxon to Tinamous and is not as closely related to the other ratites as previously thought; shows convergence on large terrestrial birds
280
Apterygiidae
Small, flightless, and their eggs fill their entire body cavity
281
Rheidae + Casuariidae
Have quills on their arms, and fight using their feet, which have large, sharp claws. Some have casks on top of their heads
282
What is significant about the cask on the head of a cassowary?
Can be used to understand how dinosaurs developed their casks (none as a juvenile but grows over time)
283
Describe locomotion in Struthionidae
At slower speeds, their limbs are unloaded and force is exerted horizontally. At higher speeds, their limbs are axially loaded and force is exerted vertically, which is more efficient at greater speeds
284
The shorter the moment arm, _________
The more likely the joint is a snap joint
285
The longer the moment arm, _________
The more likely it acts as a regular muscle
286
Why are ostriches able to achieve such high speeds despite having such a high center of mass?
They have extremely efficient snap joints and increased area of the planar surface
287
How do Struthionidae increase the area of the planar surface?
Only have two toes, but each are covered in papillae that increase surface area
288
Why is ostrich locomotion so efficient?
Being acted on my sexual and natural selection (faster = better mate but also can run from predators)
289
What effects did tooth loss in birds have on other body systems?
Complete rhamphotheca (keratinous sheath over bill bone), and muscular gizzard with gastroliths and crop
290
What effects did the development of the muscular gizzard with gastroliths and crop have on other body systems in birds?
More efficient food processing and shift of center of gravity backwards and downwards
291
More efficient food processing in birds led to:
Homeothermy and endothermy (high basal metabolic rate)
292
Sustained active flight in birds was affected by:
Reduction in total body mass (skeletal lightening), homeothermy and endothermy, center of mass shifted back and down, and stronger flight muscles, extensive skeletal fusions, and tail reduction
293
What is significant about the K-Pg boundary?
Freed niches for birds to fill and diversify
294
After the K-Pg boundary, active sustained flight allowed for:
Diversification of modes of flight
295
After the K-Pg boundary, the complete rhamphotheca allowed for:
Diversification of beak shapes and uses (preening, diet, communication, thermoregulation, etc)
296
The origin of the rhinotheca (upper sheath) and gnathotheca (lower sheath) is homologous with:
The turtle beak
297
Large component of beak diversification caused by:
Differences in allometric growth
298
Positive allometry:
Body part increased relative growth to rest of body
299
Isometry:
Body part 1:1 growth rate
300
Negative allometry:
Body part decreased relative growth to rest of body
301
What are the important factors in beak diversification?
Allometry, development, size of the bird, foraging mode, and concerted interactions between other variables
302
What is a feather?
An ectodermal organ used in birds for many functions
303
What are the functions of feathers?
Flight, insulation (thermoregulation), courtship, sensation, contouring, predation,
304
What is a rachis
The central vein of a feather
305
What is a calamus
The part of the feather that inserts into the skin
306
What is a barb
A lateral branch from the rachis
307
What is a barbule
A branch from the barb
308
What are pennaceous barbs used for?
Colour deposition, structural colour, exposed to the environment
309
What are plumaceous barbs used for?
Soft filaments that make up the undercoat used for temp regulation
310
Feather type depends on:
Proportion of plumaceous : pennaceous barbs
311
True/False? Feathers have a unique genetic regulatory system compared to other ectodermal organs
False. Develop the same way
312
What are the five types of feathers?
- contour
- down
- semiplume
- filoplume
- bristles
313
Describe the anatomy of a contour feather
The barbs are asymmetrical (one side is longer than the other), and their barbules hook together with barbules from adjacent barbs to direct the flow of air during flight
314
Function of a contour feather
Flight
315
Ratio of pennaceous to plumaceous barbs on contour feathers
Many pennaceous, few plumaceous
316
What must contour feathers have lots of to function properly?
Surface area
317
Describe the anatomy of a down feather
Almost all plumaceous, very unorganized but hold lots of volume
318
Function of a down feather
Insulation
319
Why do diving birds have shorter down feathers than flying birds despite the fact they spend lots of time in cold water?
Shorter down feathers don't hold as much air, so the bird is overall denser and is better at diving because it doesn't have to fight the buoyancy of their air
320
Describe the anatomy of a filoplume
Very very small feathers with thin rachis and pennaceous filaments at the top
321
What are the functions of filoplume feathers?
Contouring (provide space between contour feathers for easier organization), sensation (allow birds to hear), and courtship (make vibrations)
322
How do peacocks use their filoplumes to attract mates?
They shake their filoplumes which emits <25Hz vibrations to attract mates
323
If filoplumes are clipped from the caudal tract, what happens?
Birds who signs of deafness
324
Describe the anatomy of a bristle
Rachis is mostly unbranched except for the bottom, which may have a few pennaceous filaments
325
What are the functions of bristles?
Sensation (like whiskers) and predation (funnel insects into mouth)
326
Are bristles a new trait in birds?
No, many different clades have them, which suggests their MRCA likely had bristles
327
Describe the development of a down feather
1. Outpocket of the epidermis
2. Invagination in the tissue around the outpocket
3. Involution of the rachis to form barbs
4. Barbules form
5. Rachis forms
328
Describe the development of a contour feather
1. Outpocket of the epidermis
2. Invagination in the tissue around the outpocket
3. Rachis develops
4. Involution of the rachis to form barbs
5. Barbules form
329
Why must the rachis form first in contour feathers?
Provides the structure for barbs
330
Why must the barbs form first in down feathers?
Require less organization than contour feathers, main focus is volume
331
What are feather tracts?
Areas set up to grow different feathers on different parts of the body
332
How fast is tract development in birds?
Very fast! Tracts are set up 4 days after neurulation
333
What does tetrachromatic mean?
Four colour cones instead of three
334
The fourth cone in bird's eyes allows them to see:
UV light
335
Why are birds tetrachromatic?
They rely heavily on colours for communication, so they need a broader spectrum to operate with
336
What are the three types of colour birds use for their feathers?
- pigment
- structural
- iridescence
337
Describe pigment colour in birds
Pigment is deposited into the pennaceous filaments
338
Describe structural colour in birds. What colours is this used for?
The organizational pattern of molecules results in colours that would be difficult to produce with pigments; blues, purples, greens
339
Describe iridescence in birds. What colours?
Also structural, though the colour reflected depends on the angle you view them at; blues, purples, and greens
340
What are the ways in which birds care for their plumage?
- anting
- bathing
- preening
- molting
341
Describe anting in birds
They squish ant into their feathers, which acts as an anti-parasitic for ectoparasites
342
Describe bathing in birds
Bathe in either water or dirt to maintain their feathers
343
Describe preening in birds
They spread oil from their uropygial gland (found on the pygostyle) onto their feathers to protect and waterproof them
344
Describe molting in birds
They shed their feathers depending on the time of year, which is very energetically costly, so it's under a lot of selection pressure
345
Describe molting in terms of thermoregulation
Density and mass of the feathers change depending on the season (degree of change depends what kind of feather)
346
Describe molting in terms of courtship
Mandarin ducks molt into a beautiful coat for courtship and dull coat any other time of the year
347
Describe how feathers aid in predation
Owls can fly almost silently because of the anatomy of their feathers and some herons use their wings to cover water to "calm" the fish before it attacks
348
Describe the flight feathers of owls that allow them to fly so silently
Fringed tail feathers, velvety exterior of feathers, and combs on the leading edge of the wings direct airflow in a way that makes owls fly almost completely silently
349
How are feathers used in courtship?
Bright colours, iridescence, and courtship behaviours are used to attract mates (speciation)
350
Why were birds able to achieve flight?
They have drastically reduced their mass by pneumatizing their bones
351
What is pneumatization?
Bone structure seen in birds where the majority of the bone is made up of air pockets
352
What are the four skeletal contributors to flight in birds?
- furcula (wishbone)
- keel
- synsacrum
- pygostyle
353
What is the purpose of the furcula?
Increased pectoral girdle stability
354
How was the furcula formed?
Fusion of the collarbones
355
What is the purpose of the keel?
Flight muscle attachment
356
What is the purpose of the synsacrum?
Acts as a counterbalance
357
What is the purpose of the pygostyle?
Holds the rectrices (tail feathers)
358
What are the four forces that act on birds during flight? Which direction does each act in?
- gravity (down)
- lift (up)
- thrust (forward)
- drag (backward)
359
Which forces inhibit flight in birds? Which allow for flight?
Gravity and drag; lift and thrust
360
Which forces can birds optimize in flight? Which forces can't they optimize?
Lift, thrust, and drag; gravity
361
What do birds show a convergence on in relation to flight?
Wing shape (acts as an airfoil)
362
Describe how lift is generated
Air velocity on the dorsal side of the wing is faster, while on the ventral side is slower. Because the velocity is higher on the dorsal side, it is lower pressure, so the wing is lifted in the direction of the lower pressure (upwards)
363
What are the metrics of wings that impact drag and lift?
Aspect ratio and wing loading
364
Describe a high speed wing shape. Aspect ratio and wing loading?
Small, comes to a sharp point. High aspect ratio, low wing loading. Usually used for fast flapping (hummingbirds)
365
Describe an elliptical wing shape. Aspect ratio and wing loading?
Broad wing meant for short bursts of movement and not long flight. Low aspect ratio and high wing loading
366
Describe a high aspect ratio wing shape. Aspect ratio and wing loading?
Long and thin. Used in active/dynamic soaring birds and is very rarely flapped. High aspect ratio and low wing loading
367
Describe a slotted high-lift wing shape. Aspect ratio and wing loading?
Long and broad, used for passive/static soaring. Low aspect ratio and high wing loading
368
How is wing loading calculated?
Mass of bird/total surface area of the wing
369
What is wing loading?
A measure of how much mass each meter squared of the wingspan is responsible for in order to achieve flight
370
High wing loading means?
Each square meter is responsible for a high amount of mass
371
What can wing loading be related to?
Metabolic rate
372
How is aspect ratio calculated?
Wingspan^2/surface area of the wing
373
What is aspect ratio?
A measure of how much space there is under the wing for air to flow over (measures maneuverability)
374
High aspect ratio means?
Low maneuverability
375
What is the function of the primary and secondary feathers?
They function as independent ailerons (control pitch, yaw, and roll)
376
What is the function of the covert feathers?
They reduce turbulence
377
What is the function of the alula?
Increases air velocity above the wing to reduce turbulence
378
The downstroke of the wing is controlled by the:
Pectoralis
379
The upstroke of the wing is controlled by the:
Supracoracoideus
380
Which pectoral bones are involved in bird flight?
Keel, coracoid, sternum, and furculum
381
What is powered flight?
Active use of the flight muscles
382
What is passive flight?
Using air currents to generate lift instead of flapping their wings
383
What are the three divisions of powered flight?
- full/powered
- hovering
- flapping
384
Describe full flight
Wings are almost always flapping. Seen in large birds like geese
385
Describe hovering flight
An incomplete downstroke and figure 8 motion is used to generate lift on both the upstroke and downstroke. Seen in hummingbirds
386
Describe flapping flight
Used for high wing loading. Wings touch on the upstroke and downstroke and they create lift on both, which is necessary for high wing loading species. Seen in pigeons
387
Describe dynamic soaring
Takes advantage of gravity to generate speed and air currents above the ocean to generate lift without flapping. Very energy efficient. Seen in albatrosses
388
Describe static soaring
Uses static thermal columns to generate lift, and glide down from there until they need to get back up again. They will sometimes flap to generate more lift within the column. Seen in eagles
389
Describe the relative wing loading in increasing order for the four wing types
High speed < high AR < slotted high-lift < elliptical
390
Describe the relative aspect ratio in increasing order for the four wing types
Elliptical < slotted high-lift < high speed < high AR
391
Are pelycosaurs dinosaurs?
No
392
Are pterodactyls dinosaurs?
No
393
Are plesiosaurs dinosaurs?
No
394
What defines Dinosauria?
The pelvic girdle, which allows for an erect posture
395
What is special about the dinosaurian hip that allows for their upright posture?
It has a perforated acetabulum (hole that femur fits into)
396
Perforated vs imperforated acetabulum
Perforated has a hole where it joins with the femur, imperforated just has a divot/bowl
397
How is the femur oriented in crocodylians? What kind of posture does this give them?
Femur is lateral to the pelvis, which gives them a sprawling posture due to how the muscles attach (can't physically become upright, one points ventrally, while the other points dorsally)
398
How is the femur oriented in dinosaurians? What kind of posture does this give them?
The head of the femur is offset, allowing the femur to be ventrolateral to the pelvis. This gives them an erect posture, as the muscle attachment allows for more stability for the upwards gait (both point dorsally)
399
What shape is the femur in dinosaurs that allows for their posture?
Head of the femur is offset, so it looks like an upside-down L
400
Which direction do the pubis and ischium point, respectively, in saurischian hips?
cranio-ventrally; caudo-ventrally
401
Which direction do the pubis and ischium point, respectively, in ornithischian hips?
Both point caudo-ventrally
402
Saurischia means:
Lizard-hipped
403
Ornithischia means:
Bird-hipped
404
Which clade gave rise to birds?
Saurischia
405
As the clades in Saurischia became more recent, what general trend can be seen?
A trend towards miniaturization, endothermy, and feathers
406
Describe why we see a gradual trend to miniaturization in contemporary carnivores
There is a wide range of meat variety to sustain every population
407
Describe why we see a sharp drop to miniaturization in carnivorous dinosaurs
It takes an enormous amount of resources to sustain large carnivorous dinosaurs, so they impede on other populations for food
408
Why were dinosaurs so much larger in the past than they are now?
The past was a lot warmer, thus there was more plant productivity, so herbivores flourished, so there was plentiful food for carnivores. It is much colder now, which decreases plant productivity and thus decreases the sustainable size of carnivores
409
Miniaturization is interplay between:
The changing climate and available resources
410
With a decreased body size, dinosaurs face increased _____________ and ____________, and retention of ___________________ need
Loss of heat; thermal conductance; homeothermic need
411
What is inertial homeothermy/gigantothermy?
The small SA/V ration permits retention of heat due to the sheer volume of the organism (maintains heat well)
412
Why was a shift towards endothermy seen in dinosaurs with dropping atmospheric temperatures?
As Ta decreases, miniaturization comes into effect, so heat is dissipated faster to the environment. In order to stay warm, maintaining heat from their metabolism was required
413
When was the evolution of feathers relative to the evolution of endothermy and trend to miniaturization?
As miniaturization became more prominent, feathers were evolved to insulate the body from the environment (could not rely on gigantothermy for heat retention). Endothermy evolved not long after that
414
What is the evidence used to argue for the existence of feathers before birds?
Integumentary filaments (proto-bristles) found on fossils, and osteological correlates show bumps on the bones where primitive feathers would've attached
415
List the features of Archaeopteryx that were important in determining its role as a stepping-stone to birds
- elongate digits to support flight feathers
- reduced caudal vertebrae
- pectoral girdle set up for powered flight (furcula)
- pubis directionality (points caudoventrally)
416
A fossilized feather from Archaeopteryx was discovered. What about its anatomy would suggest that it's a flight feather?
- made out of mostly pennaceous filaments
- asymmetry of barbs (one side longer than the other)
- barbs are organized, as seen in contour feathers
417
List the features of Pygostylia that were important in determining its role as a stepping-stone to birds
- caudal vertebrae fused to form the pygostyle
418
From Pygostylia, what must change to get to modern Aves? What is the general trend in these changes? When did these features diversify?
- metacarpal fusion
- keel development
- coracoid modifications
- pygostyle modifications
- rectrices
- synsacrum
- edentulousness
Strengthen active flight; after K-Pg boundary
