Questions and Answers
What is a transitional fossil?
Transitional fossils have features that are intermediate between ancestors and descendants.
Which of the following is a tetrapod?
Which evidence supports the hypothesis that four-limbed animals came from fish?
DNA analysis shows that fish are tetrapods' closest relatives. The fossil record shows more and more tetrapod-like fish before the appearance of tetrapods about 365 million years ago. Both fish and four-limbed animals are vertebrates. Fish and four-limbed animals have very similar embryos.
Why have we NOT found examples in the fossil record of every animal that ever lived on Earth?
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Why did Shubin and Daeschler search in the Canadian Arctic for fossil evidence of the transition from fish to tetrapods?
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What kind of habitat did Tiktaalik live in?
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Which were the tetrapod-like characteristics of Tiktaalik?
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How did the great transition from fish to tetrapod occur?
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Which of the following are considered reptilian characteristics of Archaeopteryx?
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Which discovery ultimately overturned the prevailing perception that all dinosaurs were large, slow, and lumbering?
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Which of the following shared characteristics of living birds and theropod dinosaurs provided support to the hypothesis that birds evolved from dinosaurs?
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How did Dr. Jack Horner's discovery of dinosaur nesting grounds support the hypothesis that birds evolved from a group of dinosaurs?
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Which pieces of evidence support the hypothesis that the first feathers served a purpose other than flight?
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Which of the following statements about bird evolution are accurate based on the evidence presented?
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Why was the discovery of organisms, such as Archaeopteryx, that have a mix of traits usually associated with two different groups considered validation of Darwin's theory of evolution?
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Without the taxonomic change of birds being considered as part of the reptile clade, what would be the consequence?
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What is the basis for categorizing the three major groups of mammals?
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Vertebrates and tunicates share what structures?
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Most members of which of the following groups are most closely associated with a wet or moist environment?
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What does the presence of a swim bladder allow typical ray-finned fish to do?
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Jaws first occurred in which extant group of fishes?
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Which of the following characteristics is shared by a hagfish and a lamprey?
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How did the evolution of the jaw contribute to the diversification of early vertebrate lineages?
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What is the major feature in coelacanths and lungfish that supports the hypothesis that they are a crucial link between other fishes and tetrapods?
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Which of the following chordates is most likely to look the LEAST like other chordates?
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Which of the following represents the strongest evidence that two of the three middle ear bones of mammals are homologous to certain reptilian jawbones?
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With which of the following statements would a biologist be most inclined to agree?
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Which of the following is NOT a diagnostic feature of the Chordata?
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What did chordate pharyngeal slits first function as?
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Which of the following are the only extant animals that descended directly from dinosaurs?
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Which of the following characteristics evolved independently in mammals and birds?
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In what respect do hominins differ from all other anthropoids?
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Which of these are amniotes?
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What group of mammals have embryos that spend more time feeding through the placenta than the mother's nipples, young that feed on milk, and a prolonged period of maternal care after leaving the placenta?
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What is believed to be the most significant result of the evolution of the amniotic egg?
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What anatomical change made depth perception possible?
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What does the conclusion about Chondrichthyes demonstrate as new evidence emerges?
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Which extant chordates are postulated to be most like the earliest chordates in appearance?
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What does the conclusion about Chondrichthyes demonstrate regarding characteristics in evolution?
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Mammals and birds eat more often than reptiles. Which of the following traits shared by mammals and birds best explains this habit?
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What is the diagnostic feature of Chondrichthyes?
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The Neanderthal DNA discovered in Homo sapiens is best explained by?
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Which of these primate groups is most closely related to humans?
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_____ are the oldest known primate group.
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What primates spend the most time walking upright?
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Which of these anthropoid groups consists of primates who are mostly tree dwellers and whose forelimbs and hind limbs are about equal in length?
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Which anatomical features of the 3.2-million-year-old Australopithecus fossil known as 'Lucy' suggest she was a bipedal hominid?
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Vertebrates and tunicates have what structures?
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Living vertebrates can be divided into two major clades. Select the appropriate pair.
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Unlike eutherians, both monotremes and marsupials?
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Which clade does not include humans?
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As hominins diverged from other primates, which of the following appeared first?
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Which of the following could be considered the most recent common ancestor of living tetrapods?
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Study Notes
Transitional Fossils and Evolutionary Evidence
- Transitional fossils display features that bridge gaps between ancestors and descendants, providing insights into evolutionary processes.
- Evidence from DNA analysis indicates that fish are the closest relatives of tetrapods, supporting the evolution of four-limbed animals from fish.
- The fossil record reveals increasing similarities between fish and tetrapod-like creatures prior to the emergence of true tetrapods around 365 million years ago.
- Both fish and four-limbed animals share vertebrate traits and exhibit similar embryonic development patterns.
Fossilization and Discovery
- To fossilize, an organism must be quickly buried in sediment or ash to prevent decomposition, which makes finding fossils rare.
- Many fossils remain buried and can only be uncovered through erosion or excavation processes.
- Shubin and Daeschler targeted Canadian arctic strata older than 365 million years for fossil evidence of the transition from fish to tetrapods.
Tiktaalik: A Key Transitional Species
- Tiktaalik inhabited warm, freshwater swamps and displayed both fishlike and tetrapod-like traits, such as interlocking ribs and a neck.
- The gradual transition from fish to tetrapod was marked by a series of intermediate forms.
Archaeopteryx and the Evolution of Birds
- The Archaeopteryx fossil, dating back 150 million years, combines birdlike features (feathered wings) with reptilian characteristics (teeth, claws, long tails).
- Deinonychus, a small theropod dinosaur, challenged the notion of dinosaurs as large and slow by showcasing agile features.
- Shared traits between birds and theropods, such as hollow bones, feathers, S-shaped necks, and the wishbone, support the hypothesis that birds evolved from dinosaurs.
Nesting and Feather Evolution
- Dinosaur nesting grounds discovered by Dr. Jack Horner suggest that dinosaurs cared for their young similarly to modern birds.
- Some early feathered theropods were not capable of flight, indicating that feathers may have initially evolved for purposes other than flight, such as communication or insulation.
Taxonomy and Classification
- Birds are considered part of the reptile clade; this classification change prevents Reptilia from being paraphyletic.
- Mammals are classified into three major groups based on their reproductive methods, including monotremes, marsupials, and eutherians.
Characteristics and Features of Chordates
- Vertebrates and tunicates share key traits like a notochord and a dorsal, hollow nerve cord.
- Most amphibians are closely associated with moist environments, while a swim bladder in ray-finned fish allows buoyancy without constant swimming.
Evolutionary Milestones
- Jaws first appeared in chondrichthyans, while the evolution of the jaw facilitated access to new food sources.
- Coelacanths and lungfish exhibit limb-like skeletal structures, acting as a critical link between fishes and tetrapods.
- Adult tunicates resemble primitive chordates less than other groups, while early chordates are postulated to be similar to lancelets.
Anecdotes from Evolutionary History
- The movement of ear bones from jaw development in mammals serves as strong evidence for the evolutionary link between reptiles and mammals.
- Hominins distinguish themselves from other anthropoids through bipedalism, with humans most closely related to apes.
Extant Groups and Evolutionary Changes
- The oldest acknowledged primate group is the prosimians, while hominids are recognized for their upright walking.
- Australopithecus fossils, like "Lucy," exhibit anatomical features indicating bipedal locomotion, critical to hominin evolution.
Final Insights into Evolutionary Relationships
- The majority of extant chordates, including humans, fit within established phylogenetic clades, with species descended from common ancestors exhibiting varying adaptations.
- Significant traits like endothermy evolved independently in birds and mammals, enhancing their survival and activity levels compared to reptiles.
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Description
Test your knowledge on transitional fossils and the evolution of tetrapods with this quiz. Explore how DNA analysis supports the connection between fish and four-limbed animals. Perfect for students mastering concepts from Chapter 34 in Biology.