Lepidosauria (tuatara and squamata)

Question 1

What are some diagnostic features of Lepidosauria? (5)

Answer 1

Diapsid OR modified diapsid skull, body covered by keratinous overlapping scales, periodically shed skin cells in sheath or patches, cloacal slit is transverse (rather than longitudinal), caudal vertebrae from tail with weak plane for autonomy

Question 2

What are some features of the Tuatara? What clade does it belong to?

Answer 2

From the clade Rhynchocephalia, lives only on the small islands off the coast of New Zealand, used to live on main islands until the Māori people introduced Pacific rats which ate their eggs. They are nocturnal and live in burrows that may be shared with birds, have a lower body temp compared to normal lizards, bask in sun during the day. Diet consists of invertebrates and some birds

Question 3

Why do remote oceanic islands have fragile fauna?

Answer 3

1. They are far from the nearest land mass
2. They are not connected to it via a continental shelf

Question 4

What are some diagnostic features of tuataras? (6)

Answer 4

They are small (60cm long as adults), inflexible skull, unmodified diapsid skull, have parietal eye (covered by skin after 4-6 mths), upper jaw bears two rows of teeth with the outer row being true teeth and the inner row being palate denticles, vertebral ribs with uncinate process, gastralia, no true penis

Question 5

What is different about the fauna in island environments compared to mainland? What is the downside to living on an island?

Answer 5

Island fauna are more protected from predation, competition, as well as infection and there are also dramatic changes to body size, locomotion, as well as diet and other ecological factors. Formerly widespread organisms can colonize islands and sometimes survive even after disappearing elsewhere. The downside is that island ecosystems are easily disrupted by humans and their pets/pests

Question 6

What are some features of Squamata?

Answer 6

Most diverse group of extant non-avian reptiles.
Use three body types: typical quadrupedal lizard, Amphisbaenians with reduced limbs, as well as limb less such as snakes with cranial kinesis
Their diet is carnivorous, herbivorous, as well as insectivorous, some groups have a specific preference
They have cranial kinesis, no gastralia, hemipenis, determinate growth which leads to lower weight, easier access to prey insects and immune to the danger of falling.

Question 7

What is sprawling posture like in Lepidosauria?

Answer 7

But body elevated higher than Lissamphibia’s, trunk of body undulates during locomotion and they are susceptible to carriers constraints where there is a conflict between locomotion and ventilation which rely on trunk muscles

Question 8

What is reproduction like for Lepidosauria?

Answer 8

They have a grooved hemipenis (only use one at once), parthogenesis (female reproduction without male input) viviparity and parental care, and sex determination is temperature dependent

Question 9

What are the the 7 clades of Squamata

Answer 9

Gekkonidae, Amphisbaenidae, Scincidae, Chamaeleonidae, Iguanidae, Helodermatidae, and Varanidae

Question 10

What are some features of Gekkonidae? (5) What is their distribution?

Answer 10

Worldwide distribution insectivorous, large eyes with transparent spectacle, diurnal species with round pupil and nocturnal species with vertical pupils, long tail with variable morphologies, tail usually with caudal autonomy, toe pads and belly are sticky, covered in microscopic brush-like bristles in hierarchical fashion, have an adhesive effect so they can stick to vertical surfaces (due to intermolecular forces and Van Der Waals forces)

Question 11

What are some features of Scincidae? (7)

Answer 11

worldwide, can be many different types of locomotion, insectivorous, head is often wedge-shaped, stout/elongated body, tail has caudal autonomy, limb reduction/loss is common

Question 12

What is the genus of Scincidae that has a variety of digit loss?

Answer 12

Hemiergis, ranges from 2-5 digits lost, then there are less than 5 digits present digit I is lost first and then V and then II

Question 13

What are some features of Amphisbaenidae?

Answer 13

They are fully fossorial and eat arthropods, eye is absent or covered with skin, they are limbless (except Bipes), they lack external gill opening, have a solid skull without temporal fenestrae, short/expanded snout, girdles and RT ling reduced/lost and short tail

Question 14

What are the three snout orientations of Amphisbaenidae? What are they each used for ?

Answer 14

Blunt snout: burrowing through lose soil by rotating head
Shovel snout: burrowing through firmer soil by lifting soil with head
Keel head: burrowing through firm soil by moving head side to side

Question 15

What are some features of Chamaeleonidae? (6)

Answer 15

Prehensile tail, eyes move independently, arboreal and insectivorous, projectile tongues, zygodactylous feet (bones are unfused), can rapidly change colors (changing the nano guanine crystals in the skin) to become cryptic to hide from predators or for social signals

Question 16

What are some features of Iguanidae? (4)

Answer 16

Terrestrial/arboreal, herbivorous, tooth row on lower jaw takes up more than 50% of the mandible, have many diverse forms such as the basilisk

Question 17

What is the special species of Iguanid and why are they different?

Answer 17

Amblyrhynchus, found on the Galapagos islands, live on rocky shores and have specialized nasal glands to remove excess salt, and they swim/dive to eat algae

Question 18

What are some features of Helodermatidae? How many species in how many genera?

Answer 18

2 species in one genera Heloderma, they are omnivorous, large body size, head and body covered by button shaped osteoderms which gives body a beaded appearance (bones are formed within skin, and they are fused to the skull, tail lacks caudal autonomy, lower jaw has venom glands which are modified from salivary glands and it is delivered via ducts between teeth/lips

Question 19

What hormonal peptide is extracted from what clade for treatment of type 2 diabetes?

Answer 19

Helodermatidae and exendin 4

Question 20

What are the features of Varanidae? How many species/genus?

Answer 20

1 GENUS (Varanus), carnivorous and insectivorous, LARGE, upright position but not quire parasagittal, detects volatile oils from decomposing carcasses, teeth have serrations and are blade-like, lower jaw has venom glands and tail lacks caudal autonomy

Question 21

What are some general features of Serpentines?

Answer 21

They can be terrestrial, arboreal, fossorial and aquatic, they are all carnivorous or insectivorous predators, and they can be highly specialized

Question 22

What are some diagnostic features of Serpentines? (5)

Answer 22

Elongate body with increased vertebrae, lack girdles and limbs however some species retain rudimentary hind limb, and some have spurs. The ventral side of their body is covered in scutes (rectangular scales) that are often metameric and assist in locomotion, they have an eye with a mobile transparent eyelid, their eye has no ciliary body to deform the lens therefore they push the eye in and out to focus (same as fish), they have no external ear, tympanic membrane or middle ear so instead they gather vibrations through their skeleton (usually the lower jaw) and then it to the inner ear

Question 23

What are the five types of serpentine locomotion?

Answer 23

1. Undulation: use scutes to grip the ground and move forward to lift body off the ground to reduce friction
2. Sidewinding: limit contact with the ground to 1-3 points and body swings forward
3. Concertina: anchors portions of the body against the substrate to push against them to move forward
4. Rectilinear: rib walking with scutes
5. Gliding: unique to small groups, flare out ribs

Question 24

What are the five clades of snakes?

Answer 24

Colubridae, Elapidae, Viperidae, Boidae, Leptotypholidae

Question 25

What are diagnostic features of Colubridae? (4)

Answer 25

Small and harmless to large and venomous, worldwide, opisthoglyphous fang (rear pointed and placed towards the back of maxilla), fangs are solid or with grooves and have low mobility

Question 26

What are the diagnostic features of Boidae? (4)

Answer 26

They look like pythons and include the green anaconda which is the heaviest snake in the world, have a long head and long mouth, have vestigial hindlimbs in the form of spurs near the cloaca and the DO NOT produce venom

Question 27

What are the diagnostic features of Leptotypholidae? (4)

Answer 27

Small, eye and gape are reduced, only lower jaw bears teeth, use knotting

Question 28

What are the diagnostic features of Viperidae? (5)

Answer 28

Includes western rattlesnake (Crotalus oreganus), everywhere except antarctica and Australia, they are venomous and have a solenoglyphous fang (large fang is only tooth on the front end of the maxilla), fangs are hollow with high mobility

Question 29

What are the diagnostic features of Elapidae? (6)

Answer 29

Includes king cobra (Ophiophagus hannah), they are all small (except KC) have nasal valves in marine species to prevent water from entering the nasal passageways, have proteroglyphous fang (large fang on front of maxilla with small teeth behind it), fangs are hollow and teeth are solid and do not have high mobility

Question 30

What are the two fossil relatives of Lepidosauria?

Answer 30

Choristodera and Sauropterygia

Question 31

What are the three clades contained within Sauropterygia?

Answer 31

Placodontia, Pachypleurosauridae, Plesiosauria (Pliosaurids and Plesiosaurids)

Question 32

What are features of Choristodera? (3)

Answer 32

Found in the Jurassic to Paleogene and they were thought to be semi-aquatic after Cretaceous. The earliest one is the Cteniogenys

Question 33

What are features of Placodontia? (6)

Answer 33

Most basal, Triassic, short neck, large skull, paddle hands and feet, flat/crushing teeth for hard invertebrates

Question 34

What are some features of Pachypleurosauridae? (5)

Answer 34

Slender body, long skulls and small teeth, probably fed on invertebrates and small fish, thick ribs to decrease buoyancy, and live birth

Question 35

What are features of the two types of Plesiosauria?

Answer 35

Pliosaurids: large, stocky necks, long jaw and skull, swam rapidly after sizable prey
Plesiosaurids: small skull, long necks, slow swim and small prey

Question 36

What are some features of fossil rhynchocephalians?

Answer 36

Small, terrestrial, lizard-like, insectivorous, modified diapsid skulls

Question 37

What are the earliest fossil serpents?

Answer 37

3 jaw bones from the Mid-Jurassic England from Eophis Underwoodi