''Pengana robertbolesi'', also referred to as the flexiraptor, is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

bird of prey Birds of prey or predatory birds, also known as raptors, are hypercarnivorous bird species that actively hunt and feed on other vertebrates (mainly mammals, reptiles and other smaller birds). In addition to speed and strength, these predators h ...

that lived during the Early

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

(23–16 million years ago). Living relatives of ''P. robertbolesi'' may include the harriers. When alive, it may have resembled a cross between the

secretary bird The secretarybird or secretary bird (''Sagittarius serpentarius'') is a large, mostly terrestrial bird of prey. Endemic to Africa, it is usually found in the open grasslands and savanna of the sub-Saharan region. John Frederick Miller described ...

and

crested caracara The crested caracara (''Caracara plancus'') is a bird of prey in the family Falconidae. It is found from the southern United States through Central and South America to Tierra del Fuego. It was formerly placed in the genus ''Polyborus''. Descri ...

. Its remains were found in Riversleigh,

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...

, Australia. ''P. robertbolesi'' is only known from a

tibiotarsus The tibiotarsus is the large bone between the femur and the tarsometatarsus in the leg of a bird. It is the fusion of the proximal part of the tarsus with the tibia. A similar structure also occurred in the Mesozoic Heterodontosauridae. These sm ...

(ankle bone). However, this is of most peculiar construction, allowing the leg to be swivelled backwards and sideways. The

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

was thus well adapted to reaching into holes and crevices and extracting prey. The vernacular name ''flexiraptor'' was coined to reflect this ability.

References

* Boles, W. E. (1993a): ''Pengana robertbolesi'', a peculiar bird of prey from the Tertiary of Riversleigh, northwestern Queensland, Australia. '' Alcheringa'' 17: 19–26. * Boles, W. E. (1993b): The fabulous flexiraptor: a bird with a strange twist. '' Riversleigh Notes'' 22: 2–3.

External links

Australian Museum
Birds of prey Accipitridae Fossil taxa described in 1993 Miocene birds of Australia Riversleigh fauna {{Accipitriformes-stub