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Animal kingdom > Lepidosauria > Flashcards

Lepidosauria Flashcards

1
Q

Amniota: animals with an amniote egg, adaptations for land; divided into the Sauropsida and Synapsida

Sauropsida

division 1
Archosauria
Lepidosauria

division 2
Tuataras (Rhynchocephalia)
Lizards and Snakes (Squamata)

A

…

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2
Q

Summary

Amniota:

A

animals with an amniote egg, adaptations for land;

divided into the Sauropsida and Synapsida

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3
Q

Summary

division of sauropsida

A

Archosauria

Lepidosauria

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4
Q

Summary

division of lepidosauria

A

Tuataras (Rhynchocephalia)

Lizards and Snakes (Squamata)

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5
Q

What is a reptile

3 points

A
  1. All tetrapods whose ancestors had an amniote egg

Excludes the Lissamphians

Includes the mammals and birds

  1. Amniota
    Allow fertilised eggs to be laid on land

2 lineages

Synapsida
Sauropsida [focus of this deck]

  1. Not a taxonomic rank
    Paraphyletic or polyphyletic, depending on definition - Usually equates to Amniota
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6
Q

Amniota

2 points

A
  1. Evolved from the amphibian reptilomorphs about 312 Mya
  2. The amniote egg
    Extra-embryonic membranes: amnion, chorion, allantois

water-tight

allows gas exchange

copes with nitrogenous waste

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7
Q

Sauropsida 3 points

A
  1. One of two amniote radiations (the other is the Synapsida)
  2. All amniotes descended from the last common ancestor of extent reptiles and birds
  3. Lack a clearer definition based on morphology

Sauropsida [divides into]

Parareptilia
Diapsida [divides into]

Lepidosauromorpha
Archosauromorpha

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8
Q

Diapsida

Lepidosauromorpha

A
  1. Sprawling gait

Trunk and tail have sinusoidal movement

  1. Sliding “joint” in shoulder
  2. Pleurodont dentition
    Sides fused to inner surface of jaw bone
  3. Hemipenis
  4. Scales are keratinised structures of epidemis
    overlapping
    shed collectively
  5. Caudal autotomy
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9
Q

Diapsida

Archosauromorpha

A
  1. Parasagittal gait
    Limbs parallel to vertebral column
  2. Reduction / loss of sternum
  3. Thecodont dentition
    Teeth in sockets
  4. Penis
  5. Scutes made of dermis,
    may have bony component
    Non-overlapping
    shed in flakes
  6. Cannot shed tails
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10
Q

Ichthyopterygia
[division from lepidosauromorpha]
5 points

A

1/ Extinct taxon of aquatic lepidosauromorphs, dating from approx. 250 Mya

  1. Terrestrial ancestor that probably hunted in shallow water
  2. Later forms adapted for deep diving
  3. Large eyes, stiff trunk
  4. Live young, may have been warm-blooded
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11
Q

What is a lepidosaur

3 points

A
  1. A sauropsid amniote
  2. Only living members of the Lepidosauromorpha
  3. Modern tuatara, snakes, lizards
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12
Q

lepidosaur

Body Plan

A
  1. Ancestor was lizard-like
  2. Dry scaly skin with few dermal glands
    Shedding mechanisms
  3. Paired hemipenes in eversible pouches
  4. Hooked fifth metatarsal
    Like a mammalian heel
  5. Fracture planes in tail vertebrae for caudal autotomy
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13
Q

lepidosaur

Respiration

A
  1. Lungs lack bronchioles

Simple hollow sacs with internal folds

Large lizards have interconnected chambers

Snakes have one working lung

  1. No diaphragm
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14
Q

lepidosaur

Circulation

A
  1. Three-chambered heart

Two atria, one ventricle

Partial mixing of oxygenated and deoxygenated blood

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15
Q

lepidosaur
Digestion
2 points

A
  1. Simple, J-shaped stomach
  2. Temperature affects speed of digestion
    May not eat for months
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16
Q

lepidosaur

2 points

A
  1. Excrete uric acid with some ammonia and urea
    Uric acid secreted rather than filtered
  2. Snakes have one kidney
17
Q

lepidosaur
Nervous system
3 points

A
  1. Brain < 1% of body mass
  2. Expanded cerebrum and cerebellum compared to amphibians
  3. Spinal cord extends to tip of tail
18
Q

lepidosaur
Senses
3 points

A
  1. Vary according to dominant sense
  2. Vomeronasal organ

airbourne molecules transferred to Jacobson’s organ

  1. Usually poor hearing
19
Q

lepidosaur
Reproduction
3 points

A
  1. Sexual selection
  2. Males have hemipenes, usually inverted within their bodies
    Use one at a time, alternate
  3. Oviparous, viviparous and ovoviviparous species
  4. Parthenogenesis
20
Q

Rhynchocephalia
[division from lepidosaurmorpha]
(Sister-group to lizards and snakes)
4 points

A
  1. Pineal eye
  2. Acrodont teeth (fused to jaw bone)

Two parallel rows of teeth in upper jaw

Overhanging, incisor-like teeth

  1. Gastralia (ventral ribs, lost in squamates)
  2. Rich history in Mesozoic Era, now only 1 species

The tuatara Sphenodon punctatus

21
Q

Squamata
[division from lepidosaurmorpha]
3 points

A
  1. Kinetic (mobile) quadrate bone in skull
  2. Permits swallowing or large prey items
  3. Generalists have uniform teeth

Heterogeneous teeth

Highly specialised teeth of snakes

22
Q

Squamata: Gekkota

2 points

A
  1. Geckos

Long tails (equal to body length)

Often nocturnal

Adhesive toe pads in some arboreal species

  1. Australasian legless lizards

No pectoral skeleton

Vestigial hindlimbs and pelvic
girdle

Diurnal

23
Q

Squamata: Scincomorpha

2 point

A
  1. Skinks

No pronounced neck

Relatively small legs (some are legless)

Digging / burrowing adaptations

Carnivorous / insectivorous

  1. Girdled lizards
24
Q

Squamata: Lacertoidea

3 points

A
  1. “True” lizards
    Slender bodies and long tails
  2. Whiptails and tegus

Large rectangular scales ventrally, granular scales dorsally

Forked tongue

Some species wholly female

  1. Amphisbaenians or worm lizards

Burrowing mode of life

All species are limbless except for Bipes

Rings of scales

25
Q

Squamata: Toxicofera

A
  1. Forked tongue
  2. Venom

Molecular evidence for an early evolution of venom (200 Mya)

Originally for digestion of plants?

Animal kingdom (14 decks)

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