Tiktaalik

Definition

Tiktaalik is an extinct genus of lobe-finned fish that lived about 375 million years ago and is considered a crucial transitional form between fish and tetrapods. Its discovery provided significant evidence of the evolutionary transition from aquatic to terrestrial life, showcasing important anatomical adaptations that illustrate how vertebrates adapted to life on land.

5 Must Know Facts For Your Next Test

1. Tiktaalik had a flat skull, a neck, and functional wrist bones, features that allowed it to prop itself up and navigate in shallow waters or on land.
2. The discovery of Tiktaalik in 2004 in the Canadian Arctic was groundbreaking as it was the first fossil found showing characteristics bridging the gap between fish and early land-dwelling vertebrates.
3. It possessed both gills for breathing underwater and primitive lungs, suggesting an ability to survive in both aquatic and potentially terrestrial environments.
4. The forelimbs of Tiktaalik contained jointed bones similar to those found in tetrapod limbs, indicating the evolutionary shift toward the development of limbs capable of supporting weight on land.
5. Tiktaalik's anatomy provides key insights into the evolutionary adaptations required for the transition from water to land, highlighting the gradual changes over millions of years.

Review Questions

• How does Tiktaalik illustrate the concept of transitional forms in evolution?
  • Tiktaalik serves as a prime example of a transitional form because it exhibits both fish-like and tetrapod-like characteristics. It had features such as fins with wrist-like bones that resemble the forelimbs of tetrapods, demonstrating how anatomical changes facilitated movement from water to land. Its mixed traits allow scientists to understand the gradual evolutionary process and highlight key adaptations that were essential for vertebrates transitioning to terrestrial habitats.
• Discuss the significance of Tiktaalik's anatomical features in understanding vertebrate evolution.
  • The anatomical features of Tiktaalik are significant because they showcase critical adaptations that contributed to vertebrate evolution. Its flat skull and functional neck suggest increased mobility and flexibility needed for navigating shallow waters or moving onto land. The presence of both gills and lungs indicates a versatile respiratory system, allowing it to thrive in varied environments. These traits provide direct evidence supporting the evolutionary link between aquatic fish and terrestrial tetrapods.
• Evaluate the impact of Tiktaalik's discovery on our understanding of the evolutionary transition from water to land among vertebrates.
  • The discovery of Tiktaalik had a profound impact on our understanding of vertebrate evolution as it filled crucial gaps in the fossil record regarding the transition from water to land. By providing concrete examples of anatomical features associated with this major evolutionary shift, Tiktaalik allowed researchers to reconstruct how early vertebrates adapted their bodies for life on land over time. Its findings sparked further research into transitional fossils and underscored the importance of studying these forms to fully comprehend the complexities of evolution.

Related terms

Tetrapod: Tetrapods are a superclass of vertebrates that include amphibians, reptiles, birds, and mammals, characterized by having four limbs or limb-like structures.

Lobe-finned fish: Lobe-finned fish are a group of bony fish characterized by fleshy, lobed fins that are more similar in structure to the limbs of tetrapods than the fins of other fish.

Transitional fossil: Transitional fossils are remains of organisms that exhibit traits common to both an ancestral group and its derived descendant group, providing evidence for evolutionary changes.