Mammal Species of the World: The Definitive Taxonomic Reference
In the field of mammalogy—the scientific study of mammals—having a standardized, authoritative record of every known species is essential for research and conservation. Mammal Species of the World (MSW) serves as this critical benchmark, providing comprehensive descriptions and bibliographic data for the world's mammal species.
By organizing species into a structured taxonomic framework, MSW allows scientists to track biodiversity and ensure that researchers across the globe are using consistent nomenclature when referring to specific animals.
The Evolution of the Reference Work
The publication has undergone several iterations to keep pace with new scientific discoveries. The third edition, published in late 2005, was edited by Don E. Wilson and DeeAnn M. Reeder. To ensure broader accessibility, an online version of this edition is hosted by Bucknell University.
The Transition to the Fourth Edition
The responsibility for compiling and updating MSW was entrusted to the Checklist Committee of the American Society of Mammalogists. This committee entered into a contract with Johns Hopkins Press to produce a fourth edition, edited by DeeAnn M. Reeder and Kristofer M. Helgen.
To modernize the workflow, the database was made editable for authors, allowing for more frequent updates via the web. While the fourth edition was originally anticipated for release in 2017 and later deferred to 2019, it remained unpublished as of 2025.
Modernizing Mammal Data
As the needs of the scientific community evolved, the organizational structure behind the reference also changed. The Checklist Committee was eventually repurposed into the Biodiversity Committee.
In 2018, this committee released and began maintaining the Mammal Diversity Database, providing a more dynamic way to track the diversity of mammal species than a traditional printed volume.
Key Facts
- Purpose: Provides descriptions and bibliographic data for all known mammal species.
- 3rd Edition: Published in 2005, edited by Don E. Wilson and DeeAnn M. Reeder.
- 4th Edition Editors: DeeAnn M. Reeder and Kristofer M. Helgen.
- Publisher: Johns Hopkins Press (for the 4th edition).
- Digital Evolution: The Checklist Committee became the Biodiversity Committee, which now manages the Mammal Diversity Database.
| Version/Tool | Key Editors/Entity | Status/Date | Primary Format |
|---|---|---|---|
| 3rd Edition | Wilson & Reeder | 2005 | Print & Online (Bucknell University) |
| 4th Edition | Reeder & Helgen | Deferred (as of 2025) | Print (Johns Hopkins Press) |
| Mammal Diversity Database | Biodiversity Committee | Released 2018 | Digital Database |
Frequently Asked Questions
What is Mammal Species of the World?
It is a standard reference work in mammalogy that provides taxonomic descriptions and bibliographic data for all known species of mammals.
Who edited the third edition of MSW?
The third edition, published in 2005, was edited by Don E. Wilson and DeeAnn M. Reeder.
What happened to the fourth edition of MSW?
The fourth edition, edited by DeeAnn M. Reeder and Kristofer M. Helgen and contracted to Johns Hopkins Press, was deferred from 2017 to 2019 and had not been published as of 2025.
What is the Mammal Diversity Database?
Released in 2018, the Mammal Diversity Database is a tool maintained by the Biodiversity Committee (formerly the Checklist Committee of the American Society of Mammalogists) to track mammal species.
Where can the third edition be accessed online?
An online version of the third edition is hosted by Bucknell University.