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The Fossil Record

The Fossil Record

The fossil record documents only a small fraction of all organisms that have ever inhabited Earth. Fossilization is a rare process, and most organisms never become fossils. Moreover, the fossil record only exhibits fossils that have been discovered. Nevertheless, sedimentary rock fossils of long-lived, abundant, hard-bodied organisms dominate the fossil record. These fossils offer valuable information, such as an organism's physical form, behavior, and age. Studying the fossil record helps...

What is Evolutionary History?

What is Evolutionary History?

Scientists record evolutionary history by analyzing fossil, morphological, and genetic data. The fossil record documents the history of life on Earth and provides evidence for evolution. However, both fossil and living organisms offer evidence that outlines Earth’s evolutionary history.

Convergent Evolution

Convergent Evolution

Evolution shapes the features of organisms over time, ensuring that they are suited for the environments in which they live. Sometimes, selection pressure leads to the rise of similar but unrelated adaptations in organisms with no recent common ancestors, a process known as convergent evolution.

The Evidence for Evolution

The Evidence for Evolution

Genetic variations accumulating within populations over generations give rise to biological evolution. Evolutionary changes can result in the formation of novel varieties and entire new species. These changes are responsible for the diverse forms of life inhabiting the planet. The evidence for evolution suggests that all living organisms descended from common ancestors.

Phylogeny

Phylogeny

Phylogeny is concerned with the evolutionary diversification of organisms or groups of organisms. A group of organisms with a name is called a taxon (singular). Taxa (plural) can span different levels of the evolutionary hierarchy. For instance, the group containing all birds is a taxon (comprising the class Aves), and the group of all species of daisies (the genus Bellis) is a taxon. Phylogenies can likewise include just one genus (i.e., depict species relationships) or span an entire kingdom.

Non-vascular Seedless Plants

Non-vascular Seedless Plants

The diverse plant life on Earth—consisting of nearly 400,000 species—can be divided into three broad categories based on biological characteristics: nonvascular, seedless vascular, and seed plants.

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Related Experiment Video

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Using Pharmacological Manipulation and High-precision Radio Telemetry to Study the Spatial Cognition in Free-ranging Animals

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Palaeontology: turtles in transition.

Michael S Y Lee¹

¹Earth Sciences Section, South Australian Museum, North Tce, Adelaide 5000, Australia. mike.lee@samuseum.sa.gov.au

Current Biology : CB

|June 22, 2013

Summary

The origin of turtles remains a puzzle in vertebrate paleontology. The reptile Eunotosaurus, with its shell-like structure, may be a key transitional fossil.

Area of Science:

Paleontology
Evolutionary Biology
Vertebrate Zoology

Background:

The evolutionary history of turtles is incompletely understood, representing a significant gap in the fossil record.
Identifying transitional fossils is crucial for reconstructing the evolutionary pathways of major vertebrate groups.

Purpose of the Study:

To investigate the potential of Eunotosaurus as a transitional fossil in turtle evolution.
To analyze the anatomical features of Eunotosaurus, particularly its shell-like structures.

Main Methods:

Comparative anatomical analysis of Eunotosaurus fossils.
Examination of paleontological evidence related to early turtle evolution.

Main Results:

Eunotosaurus exhibits a rudimentary shell structure.

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This shell bears resemblance to the carapace of modern turtles.

Conclusions:

Eunotosaurus presents compelling evidence as a potential transitional form in the origin of turtles.
Further research on Eunotosaurus can illuminate the early evolution of chelonian (turtle) morphology.