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VERTEBRATE EVOLUTION Flashcards

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1
Q

Chordate characteristics of Vertebrates

A

-Vertebral column
-Cranium
-Endoskeleton of Cartilage or Bone

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2
Q

What significant transition occurred during the Devonian Period?

A

The rise of tetrapods, marking the transition from water to land

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3
Q

What diseases threaten amphibian populations?

A
  • Ranaviruses
  • Chytridiomycosis
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4
Q

What adaptations occurred during the transition from bony fish to tetrapods?

A
  • Fins evolved into limbs
  • Development of lungs
  • Changes in skeletal structure for land movement
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5
Q

What is the Gill Arch Hypothesis?

A

It explains how hinged jaws evolved from modifications of the first two gill arches in early vertebrates

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6
Q

What are the three types of feathers found in birds?

A
  • Contour Feathers
  • Down Feathers
  • Flight Feathers

Contour feathers provide shape and protection, down feathers provide insulation, and flight feathers are essential for flight.

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7
Q

What does the Endoskeleton of Vertebrates consist of?

A

The cranium and vertebral column, composed of either bone or cartilage

It provides structural support and typically includes two pairs of appendages.

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8
Q

What distinguishes hagfishes from lampreys?

A

Hagfishes are deep-sea scavengers with elongated bodies and no internal bones, while lampreys are found in freshwater and marine environments, characterized by a sucker-like mouth.

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9
Q

If early mammals had remained ectothermic like reptiles, what might have affected their evolutionary success after the K-Pg extinction?

A

Mammals would have likely remained small and unable to fully dominate ecological niches

This suggests that endothermy was a key factor in their success.

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10
Q

What is the Greek origin of the term ‘amphibian’?

A

Amphibian comes from the Greek word amphis, meaning ‘double’, and bios, meaning ‘life’.

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11
Q

What adaptations did Acanthostega exhibit?

A

Acanthostega had fully formed legs but was still aquatic.

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12
Q

What are the notable characteristics of caecilians?

A
  • Legless
  • Aquatic or burrowing
  • Reduced eyes covered by skin or bone
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13
Q

What does the Arboreal Hypothesis propose about the evolution of flight?

A

Early birds evolved from gliding to powered flight while living in trees

This hypothesis suggests a tree-dwelling origin for avian flight.

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14
Q

What is the significance of the Cranium in vertebrates?

A

It encases the brain and is essential for cephalization, concentrating sensory and nervous tissues at the head

The anterior end of the nerve cord develops into a well-defined brain.

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15
Q

What are the origins of vertebrates from invertebrate ancestors?

A

Evolved from deuterostomes such as tunicates and lancelets, with genetic and structural changes over millions of years

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16
Q

What is an amniote egg?

A

An amniote egg is a specialized egg containing extraembryonic membranes that provides protection and facilitates gas exchange.

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17
Q

What is the significance of the dentary-squamosal jaw joint in mammals?

A

Defines a mammalian characteristic

It replaces the primitive reptilian jaw joint and is crucial for efficient chewing.

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18
Q

What are key traits of early vertebrate ancestors like Haikouichthys and Myllokunmingia?

A
  • Notochord
  • Dorsal hollow nerve cord
  • Pharyngeal slits
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19
Q

What characterizes pelycosaurs?

A
  • First appeared in the late Pennsylvanian
  • Known as ‘sailbacks’
  • Relied on external heat sources

Most pelycosaurs did not have sails, and their posture was sprawling.

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20
Q

What were the initial purposes of feathers in dinosaurs?

A

Feathers likely evolved for insulation or display rather than flight.

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21
Q

What is a distinctive feature of amphibians’ skin?

A

All amphibians have bare skins, essential for the exchange of water, ions, and gases.

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22
Q

What types of feathers are found in birds?

A
  • Contour feathers
  • Down feathers
  • Flight feathers
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23
Q

How did the evolution of limbs contribute to the diversification of vertebrates?

A

Limbs provided support and maneuverability, enabling vertebrates to exploit various environments and adapt to different ecological niches

This diversification includes groups such as amphibians, reptiles, birds, and mammals.

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24
Q

______________ are a subphylum of chordates that possess a backbone (vertebral column), a cranium (skull), and an endoskeleton made of cartilage or bone. They also typically have a well-developed brain and advanced sensory systems. They are members of phylum Chordata (named for the notochord: Greek notos, “back”; chorde, “string”). Only the arthropods (Arthropoda, which includes insects, crustaceans, and spiders) rival the People vertebrates in diversity of forms and habitat.

A

Vertebrates

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25
What are the two main groups of bony fish?
* Ray-Finned Fish (Actinopterygii) * Lobe-Finned Fish (Sarcopterygii)
26
What adaptations allowed therapsids to thrive in drier environments?
* Evolved in drier regions * Fed on terrestrial plants * More mammal-like traits than pelycosaurs ## Footnote Therapsids adapted to climate changes and habitat loss that led to the extinction of pelycosaurs.
27
What is the evolutionary significance of the transition from water to land in vertebrates?
It allowed vertebrates to fully adapt to terrestrial environments and led to increased size and complexity.
28
What adaptations facilitated the transition from water to land?
* Stronger skeletons * Fins evolved into legs * Lungs for air breathing * Modified Hox genes for body development
29
What is the primary function of down feathers?
Trap air to provide insulation ## Footnote Down feathers are soft and fluffy, playing a crucial role in thermoregulation.
30
What are cyclostomes?
Jawless vertebrates including hagfishes and lampreys
31
What is Tiktaalik and its significance?
Tiktaalik is a fossil from 375 million years ago that had fish-like scales and gills but tetrapod-like limbs and a mobile neck.
32
What is a significant feature of early tetrapods' limbs?
Early tetrapods had limbs that evolved from fins with bones like humerus, radius, and ulna.
33
What traits do ostracoderms share with jawed vertebrates?
* Cellular bone * Perichondral bone * Sclerotic rings
34
Fill in the blank: The earliest mammals are classified as _______.
Mammaliaformes ## Footnote These include derived cynodonts and the first true mammals.
35
What are the structures of an amniote egg?
* Amnion * Chorion * Allantois * Yolk Sac * Shell
36
What evolutionary developments occurred during vertebrate evolution?
* Vertebral column replaced the notochord * Cranial development for brain protection * Internal skeleton improved movement and stability
37
When did the first vertebrate-like animals appear in the fossil record?
Cambrian Period (~518 Ma)
38
What characterizes acanthodians?
* Slender, shark-like bodies * Paired spines in front of their fins * Early jaw development and cartilaginous skeleton
39
What adaptation in modern mammals aids in energy efficiency?
Four-chambered heart ## Footnote This adaptation improves circulation and metabolic efficiency.
40
What evolutionary milestone allowed mammals to dominate after the dinosaurs?
Cretaceous-Paleogene (K-Pg) extinction ## Footnote This event opened ecological niches for rapid mammalian diversification.
41
What are placoderms?
Extinct group of early jawed vertebrates with bony armor and true jaws, considered one of the first to evolve hinged jaws
42
What is the significance of the evolution of the cranium in vertebrates?
Enhanced the protection of neural tissues while supporting the development of advanced sensory systems ## Footnote It also limited further cranial changes by rigidly encasing the brain.
43
What characterized the Mesozoic Era?
The Mesozoic Era is divided into the Triassic, Jurassic, and Cretaceous periods, where reptiles dominated.
44
What is the evolutionary significance of the cranium in vertebrates?
Enhances protection of neural tissues and supports advanced sensory systems ## Footnote The cranium plays a crucial role in the evolution of vertebrate sensory capabilities.
45
What defines synapsids?
Single lower temporal fenestra ## Footnote This feature allowed for stronger jaw muscles and distinguishes synapsids from other amniotes.
46
How did the emergence of jaws in early vertebrates contribute to their evolutionary success?
By providing a greater range of feeding strategies and enabling the exploitation of varied food sources ## Footnote This adaptation significantly improved their survival and ecological niches.
47
What anatomical feature evolved to provide an anchor for flight muscles in birds?
Keeled Sternum ## Footnote The keeled sternum is a significant adaptation for powered flight.
48
List the major clades of Vertebrates.
* Cyclostomata (jawless fishes like lampreys and hagfish) * Chondrichthyes (cartilaginous fishes such as sharks, skates, and rays) * Osteichthyes (bony fishes) * Amphibians * Reptiles (including birds) * Mammals
49
What are key evolutionary adaptations that facilitated the transition from water to land?
* Fins to limbs * Lungs & gills * Stronger bones & rib cage * Neck development
50
What adaptation in therapsids allowed for more efficient locomotion?
Upright limb posture ## Footnote This shift from sprawling limbs to an upright posture increased agility and efficiency.
51
What is the significance of lungfish in evolutionary history?
Lungfish can breathe air, an adaptation for surviving in low-oxygen water. ## Footnote This adaptation is crucial for survival in environments where water oxygen levels are low.
52
What are dicynodonts?
Large-bodied herbivores with toothless jaws covered by a tough horny beak ## Footnote They survived the end-Permian mass extinction and thrived in the Triassic.
53
When did tetrapods evolve from lobe-finned fish?
Tetrapods evolved from lobe-finned fish during the Devonian period (~375 million years ago).
54
What are the functional advantages of hinged jaws?
* Improved feeding strategies * Increased predatory success * Expansion of vertebrate groups
55
What explanation best integrates the roles of climate variability and natural selection in the transition from aquatic fins to weight-bearing limbs?
Fluctuating water availability due to climate variability forced vertebrates to exploit terrestrial habitats, gradually favoring individuals with rudimentary limb-like appendages ## Footnote This illustrates the impact of environmental changes on evolutionary adaptations.
56
What are the three major evolutionary radiations of synapsids?
* Pelycosaurs * Therapsids * Mammals ## Footnote Pelycosaurs are early synapsids, therapsids are more derived and mammal-like, while mammals began evolving in the Late Triassic.
57
What is the Vertebral Column?
A bony or cartilaginous column of interlocking vertebrae that replaces the notochord in adults, providing support and protecting the nerve cord ## Footnote It runs through a tube-like structure within the vertebral column.
58
What are ostracoderms?
Extinct jawless fish with armored exoskeletons made of dermal bone, considered early relatives of jawed vertebrates
59
What are Vertebrates?
A subphylum of chordates that possess a backbone, a cranium, and an endoskeleton made of cartilage or bone ## Footnote Vertebrates typically have a well-developed brain and advanced sensory systems. They are members of phylum Chordata.
60
What are the characteristics of theria?
* Live Birth (Viviparity) * Neocortex Expansion * Tribosphenic Molars ## Footnote Theria includes marsupials and placentals, with adaptations that enhance cognitive abilities and food processing.
61
What environmental factor influenced the transition from fins to limbs during the Devonian period?
Droughts forced fish to use limbs to move between water bodies, enhancing survival and eventually leading to terrestrial adaptations ## Footnote This adaptation was crucial for colonizing land.
62
When did limb evolution begin?
Limb evolution began approximately 390 million years ago during the Devonian period.
63
What is adaptive radiation in the context of birds?
The emergence of numerous species adapted to different environments after a mass extinction ## Footnote This occurred following the mass extinction event at the end of the Cretaceous period.
64
What are general characteristics of cyclostomes?
* Elongated, limbless, scaleless, and slimy * Scavengers or parasites * No specialized reproductive ducts or mineralized tissues
65
What distinguishes cartilaginous fish from bony fish?
Cartilaginous fish have a skeleton made of cartilage, while bony fish have a skeleton made of bone
66
What is Archaeopteryx known for?
Archaeopteryx is often referred to as the first known bird, exhibiting both avian and reptilian features.
67
What is the role of mucus and granular glands in amphibians?
* Mucus glands produce slippery or adhesive mucus for defense * Granular glands contain toxic substances for predator defense
68
What role did genome duplications play in vertebrate evolution?
Allowed new traits to emerge
69
What are the three modern groups of mammals?
* Monotremes * Marsupials * Placentals ## Footnote These groups represent the major lineages of modern mammals.
70
What anatomical features do theropods and birds share?
* Hollow bones * Furculum (wishbone) * Similar foot structure
71
What are the three main groups of amphibians?
* Urodela (Salamanders) * Anura (Frogs) * Gymnophiona (Caecilians)
72
What adaptations did Ichthyostega have for land?
Ichthyostega was more adapted to land, with strong limbs for walking.
73
What are some key traits that bony fish evolved?
* Swim bladders * Gill covers
74
What is the role of respiration in energy use during feeding?
Minimizes energy use during feeding ## Footnote This highlights the efficiency of energy management in organisms.
75
How do the fossil record and genetic evidence complement each other in understanding vertebrate origins?
Fossils reveal morphological transitions and genetics clarify lineage relationships, together providing a comprehensive evolutionary narrative ## Footnote This integration allows for a more complete understanding of evolutionary history.

Evolutionary Biology (12 decks)

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