Why these African birds are the last survivors of a once global lineage

Nature · Published 3 October 2026 Swipe more like this →

In short: Mousebirds are the only bird order found exclusively in sub-Saharan Africa today, but their history is far more expansive. These acrobatic, rodent-like creatures were once widespread across Europe and North America. Today, they remain as living fossils, representing a tiny, surviving fragment of a formerly diverse evolutionary lineage.

The order Coliiformes, commonly known as mousebirds, comprises six extant species confined to sub-Saharan Africa. Their common name stems from their unique behavior: they are arboreal, greyish or brown birds that scurry through foliage in search of buds, fruit, and berries, much like rodents. They are highly gregarious, often traveling in bands of about 20, and possess specialized physical traits including crests, stubby bills, and pamprodactyl feet with reversible outer toes that allow them to feed while hanging upside down.

While they are now restricted to Africa, the fossil record reveals a much broader historical range. During the Paleogene, mousebirds were distributed across Europe and North America. They are considered living fossils because the six species alive today are the only remnants of a lineage that was significantly more diverse during the early Paleogene and Miocene epochs. The family is documented as far back as the Early Paleocene, and by the Late Eocene, at least two distinct families existed: the modern Coliidae and the extinct, longer-billed Sandcoleidae.

Reconstructing the evolutionary history of these birds has proven difficult. While fossils are relatively abundant, many forms are hard to classify. For instance, sandcoleids were once thought to be a separate order, but it was later realized that this group was a paraphyletic assemblage containing ancestral Coraciiformes. Even today, some extinct genera, such as Selmes, remain difficult to assign to a specific family. These ancient relatives often displayed different ecologies; some sandcoleids, for example, possessed talons similar to modern birds of prey and left behind stomach contents containing uncrushed seeds.

The survival of the Coliiformes as a distinct group is a testament to their adaptability, yet their current isolation highlights a dramatic contraction from their prehistoric distribution. Understanding their phylogeny remains a work in progress, as researchers continue to refine the relationships between these modern survivors and their diverse, extinct ancestors found in sites ranging from the London Clay in England to the fossil beds of Wyoming.

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