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Magazine Chapter 15: Problem 14
Arrange the events in order, from most ancient to most recent. _____1 _____2 _____3 _____4 _____5 _____6 a. Cambrian explosion of diversity b. Origin of animals c. Tetrapods move onto the land d. Extinction of dinosaurs e. Homo erectus leaves Africa f. First jawed vertebrates evolve
Short Answer
Expert verified
1. b, 2. a, 3. f, 4. c, 5. d, 6. e
Step by step solution
01
Identify the Earliest Event
The earliest event is typically the one where life first shows significant developments. In this context, 'Origin of animals (b)' marks the beginning of complex life forms in Earth's history. This event precedes the Cambrian Explosion.
02
Next Major Development in Biodiversity
After the origin of animals, the 'Cambrian explosion of diversity (a)' occurred, which is a period characterized by a rapid increase in the diversity of animal life approximately 541 million years ago.
03
Evolution of Key Vertebrate Features
Following the Cambrian explosion, 'First jawed vertebrates evolve (f)' signifies an important evolutionary milestone, taking place around 430 million years ago. These jawed vertebrates are crucial for the development of more complex life forms.
04
Transition to Terrestrial Life
Subsequently, 'Tetrapods move onto the land (c)' denotes vertebrates beginning to inhabit terrestrial environments approximately 370 million years ago, allowing for evolution in a new setting.
05
Major Extinction Event
The 'Extinction of dinosaurs (d)' marks a significant event around 66 million years ago, where a mass extinction led to the disappearance of these dominant terrestrial vertebrates, creating opportunities for mammals to diversify.
06
Human Migration Event
Finally, the 'Homo erectus leaves Africa (e)' is one of the more recent events, occurring around 1.9 million years ago when early humans began to migrate out of Africa.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Cambrian explosion
The Cambrian explosion is a fascinating era in Earth's biological history, occurring about 541 million years ago. This period marks a dramatic burst of evolutionary changes where the complexity and diversity of life multiplied rapidly. Before this event, life on Earth mostly consisted of simple, unicellular organisms.
During the Cambrian explosion:
During the Cambrian explosion:
- Many major groups of animals appeared, including arthropods, mollusks, and early vertebrates.
- Novel body plans emerged, resulting in predatory creatures, complex food webs, and heightened ecological interactions.
- Fossil records from this time, such as the Burgess Shale, provide important insights into early life.
Origin of animals
The origin of animals signifies a crucial transition in the evolutionary timeline, marking the rise of multicellular organisms from simpler, single-celled ancestors. This event predates the Cambrian explosion.
Key points about the origin of animals include:
Key points about the origin of animals include:
- It likely took place in the Precambrian era, around 700 to 800 million years ago.
- Early animals were probably similar to today's sponges, featuring limited specialization and simple structures.
- Genetic studies suggest that the last common ancestor of all animals was a simple, eukaryotic organism equipped with the basic genes for multicellularity.
Vertebrate evolution
Vertebrate evolution represents a significant chapter in biological history, characterized by the development of crucial anatomical structures. One of the pivotal moments in this evolution was the emergence of jawed vertebrates.
Noteworthy aspects of vertebrate evolution include:
Noteworthy aspects of vertebrate evolution include:
- Jawed vertebrates, appearing around 430 million years ago, introduced agility and diversity in feeding strategies.
- This evolution facilitated the rise of various vertebrate groups, including fish, amphibians, reptiles, birds, and mammals.
- Adaptations, such as the development of backbones and sophisticated sensory systems, supported the transition to diverse ecological niches.
Tetrapods
Tetrapods are vital in understanding vertebrate evolution, as they represent the first vertebrates to venture onto land. This transition occurred approximately 370 million years ago.
Important points about tetrapods include:
Important points about tetrapods include:
- They evolved from lobe-finned fishes, adapting limb structures to support weight on land.
- Early tetrapods, like Acanthostega and Ichthyostega, showcase a mix of aquatic and terrestrial features.
- This transition opened new evolutionary pathways, eventually leading to the dominance of amphibians, reptiles, birds, and mammals on land.
Dinosaur extinction
The extinction of dinosaurs, occurring around 66 million years ago, was a momentous event in Earth's history. This mass extinction marks the end of the Cretaceous period and the dominance of dinosaurs as the planet's top predators.
Significant aspects of dinosaur extinction include:
Significant aspects of dinosaur extinction include:
- The primary cause is believed to be a massive asteroid impact, leading to environmental upheavals.
- This event resulted in the extinction of approximately 75% of Earth's species, including all non-avian dinosaurs.
- The extinction paved the way for mammals to diversify and occupy ecological roles left vacant by dinosaurs.
Human migration
Human migration, especially the dispersal of *Homo erectus* from Africa, significantly impacted human evolution and diversity. The migration out of Africa occurred about 1.9 million years ago, marking the spread of early humans into new territories.
Key details on human migration include:
Key details on human migration include:
- *Homo erectus* was the first hominin to expand its range beyond Africa into Eurasia.
- The migration facilitated genetic exchange, cultural evolution, and adaptations to varied environments.
- This event laid foundational pathways for the emergence of modern humans and their subsequent global colonization.
