Pengana Temporal range: | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Aves |
Order: | Accipitriformes |
Family: | Accipitridae |
Genus: | † Pengana |
Species: | †P. robertbolesi |
Binomial name | |
†Pengana robertbolesi Boles, 1993 | |
Pengana, also referred to as flexiraptor, is an extinct bird of prey that lived during the late Oligocene in what is now Queensland, Australia. It is known only from a fragment of the tibiotarsus that was collected from the Riversleigh World Heritage Area. The tibiotarsus is unusual in that it allowed for the leg to be swivelled backwards and sideways, making it well adapted to reaching into holes and crevices and extracting prey. The genus is only known from a single species, Pengana robertbolesi.
The first known fossils of Pengana were collected from the Sticky Beak site at the Riversleigh World Heritage Area, northwestern Queensland. The holotype specimen, catalogued as QM F16865, is the distal end of the left tibiotarsus. [1] A fragment of a femur from the White Hunter site might be referable to the genus on the grounds of its size, age and uniqueness compared to other Australian accipitrids. [2] [3] The Sticky Beak and White Hunter sites are both interpreted as being late Oligocene in age, which would make Pengana one of the oldest known accipitrid from Australia. [4] [1]
In 1993, Walter E. Boles described Pengana robertbolesi as a new genus and species of accipitrid on the basis of the tibiotarsus. The generic name, Pengana, is stated to have been derived from an Aboriginal word for 'hawk', although no particular language was specified. The specific name, robertbolesi, is in honour of the author's father, Richard Boles. [1]
The only remains that can be confidently assigned to Pengana is the distal end of a tibiotarsus. The piece of bone is roughly rectangular in appearance and is overall flat. It shares a lot of similarities with the extant Harrier-hawks and Crane hawk. The supratendinal bridge, which is positioned just above the condyles, is almost horizontal, angled at 30°. Both the internal and external condyles are flattened mediolaterally (side-to-side) and run parallel to the proximodistal midline of the shaft. The shaft of the tibiotarsus is compressed from the front to the back. It, however, differs from the Harrier-hawks and Crane hawk in a number of ways. For instance, both the supratendinal canal and anterior intercondylar fossa have a greater proportional width. The distal opening to the supratendinal canal is situated above the internal condyle rather than at the lateral edge of it. In addition, tibiotarsus itself is twice as large as those of the modern taxa. [1]
Boles (1993) stated Pengana to be larger than any living species of Australian bird of prey, with the notable exception of Wedge-tailed eagle and White-bellied sea eagle. [1]
Due to the lack of material, the exact position of Pengana within Acciptiridae is currently unknown. Boles (1993) dismissed the idea of a close relationship with Harrier-hawks and Crane hawks, noting that similarities between the three taxa were limited only to the intertarsal joint. This would suggest that a double-jointed ankle had at evolved independently at least three times within Acciptridae. [1] Regardless, Pengana, and the similarly aged Archaehierax , demonstrate that there was at least two different clades of accipitrids present in Australia close to the Oligocene-Miocene boundary. [5]
Features of the intertarsal joint (i.e a more horizontal supratendinal bridge and flattened distal condyles) suggests a greater degree of flexion backwards and sideways than in most acciptirids. A comparable leg-structure can be found in Crane hawks and Harrier-hawks, which allows them to easily reach into holes and crevices in search of prey. Based on the leg proportions of the two aforementioned hawks, Pengana might have had a total hindlimb length of 585-630 mm (23-25 in). With its long legs, it may have been able to probe into hollows that were at least 400 mm (15.7 in) deep. Its larger size compared to the two hawks meant that it could have hunted larger prey, specifically in the 250-300 g (0.6-0.7 lbs) range. [1]
During the late Oligocene, the Riversleigh World Heritage Area would have been predominantly covered in temperate open forest or woodland. [6] Plant fossils from the late Oligocene or early Miocene-aged Dunsinane site indicate the presence of deciduous vine thickets and sclerophyllous vegetation. [7] However, undoubted rainforest plant taxa, such as Pleiogynium wannanii , are known from the same site, which suggests that patches of rainforest would have also been present, specifically around pools or along watercourses. [8] Australia's climate at the time was cool and dry, before shifting to a more warm and wet climate during the early Miocene. [9] [6]
The Accipitridae is one of the three families within the order Accipitriformes, and is a family of small to large birds of prey with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium-sized mammals, with a number feeding on carrion and a few feeding on fruit. The Accipitridae have a cosmopolitan distribution, being found on all the world's continents and a number of oceanic island groups. Some species are migratory. The family contains 256 species which are divided into 12 subfamilies and 75 genera.
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Moorhens—sometimes called marsh hens—are medium-sized water birds that are members of the rail family (Rallidae). Most species are placed in the genus Gallinula, Latin for "little hen." They are close relatives of coots. They are often referred to as (black) gallinules. Recently, one of the species of Gallinula was found to have enough differences to form a new genus Paragallinula with the only species being the lesser moorhen.
Riversleigh World Heritage Area is Australia's most famous fossil location, recognised for the series of well preserved fossils deposited from the Late Oligocene to more recent geological periods. The fossiliferous limestone system is located near the Gregory River in the north-west of Queensland, an environment that was once a very wet rainforest that became more arid as the Gondwanan land masses separated and the Australian continent moved north. The approximately 100 square kilometres (39 sq mi) area has fossil remains of ancient mammals, birds, and reptiles of the Oligocene and Miocene ages, many of which were discovered and are only known from the Riversleigh area; the species that have occurred there are known as the Riversleigh fauna.
Mekosuchinae is an extinct clade of crocodilians from the Cenozoic of Australasia. They represented the dominant group of crocodilians in the region during most of the Cenozoic, first appearing in the fossil record in the Eocene of Australia, and surviving until the arrival of humans: the Late Pleistocene on the Australian continent and during the Holocene in the Pacific islands of Fiji, New Caledonia and Vanuatu.
Marada arcanum is a species of Vombatiformes discovered in 2001 at the Oligocene Hiatus Site at Riversleigh. It is the only member of the genus Marada. It exhibits plesiomorphic and apomorphic features making the determination of its taxonomic placement difficult. It has been placed within its own family, Maradidae. The specimen consists of the right dentary, with the first incisor but missing the crown, the whole of the horizontal ramus with intact premolar three and molars one to four. The posterior is missing the coronoid process, the articular condyle and the angular process.
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Wakaleo is an extinct genus of medium-sized thylacoleonids that lived in Australia in the Late Oligocene and Miocene Epochs.
Emuarius is an extinct genus of casuariiform flightless bird from Australia that lived during the early Miocene and late Oligocene. It is one of two known genera of emu. There are two known species in the genus, Emuarius gidju and Emuarius guljaruba. The birds in this genus are known as emuwaries. This name comes from a combination of emu and cassowary. This is due to its cassowary-like skull and femur and emu-like lower leg and foot. Because of these similarities it is phylogenetically placed between cassowaries and emus.
Warendja is an extinct genus of wombat. It is known from two species, W. encorensis from the Late Miocene Riversleigh site in Queensland, and W. wakefieldi known from the Pleistocene of South Australia, New South Wales, and Victoria. The two species are primarily distinguished by features of their enamel. It became extinct as part of the Quaternary extinction event. Warendja wakefieldi is estimated to have weighed about 10 kg, considerably smaller than living wombats. Warendja thought to be relatively basal amongst wombats, being the most primitive member to possess hypselodont cheek teeth. The morphology of the humerus of W. wakefieldi suggests that it engaged in scratch-digging.
Litokoala is an extinct genus of marsupials, and along with Nimiokoala, is closely related to the modern koala. The three genera may have diverged at an earlier date, although the drying of the continent and the expansion of Eucalyptus forests towards the late Miocene may have delayed the evolution of cranial features unique to the modern genera. This indicates that either fossil genus could be an ancestor of the modern genus, or the modern genus has a common ancestor to both. More material needs collection to improve their taxonomical relationships.
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Longmornis robustirostrata is an extinct genus and species of bird in the Old World oriole family. It was described from Early Miocene material found at the Neville's Garden fossil site at Riversleigh in north-western Queensland, Australia. Its closest living relatives are the figbirds (Sphecotheres), which its beak most closely resembles. It was named in honour of Noel Wayne Longmore, an ornithologist of the Australian Museum, and for its broad, robustly built beak. It was a mid to large-sized passerine, comparable in size to the Australian black-faced cuckooshrike, and was presumed to be a frugivore like modern figbirds.
Corvitalusoides grandiculus is an extinct species of songbird, in a monotypic genus of uncertain familial affinities, from the Late Oligocene or Early Miocene of northern Australia. It was described from a distal tibiotarsal fragment found at Riversleigh, in the Boodjamulla National Park of north-western Queensland. The bone size indicates that the bird was among the largest of songbirds, within the size range of ravens and lyrebirds.
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Cookeroo is a genus of extinct kangaroos from the Late Oligocene and Early Miocene found in fossil deposits from the Riversleigh World Heritage Area, in Australia. The genus includes two species, C. bulwidarri and C. hortusensis.
Ganawamaya is an extinct genus of quadrupedal kangaroos that lived in Australia. Its fossils have been found in various Oligocene and Miocene deposits throughout South Australia and Queensland. Four species are currently recognised, G. acris , G. aediculis, G. gillespieae, and G. couperi.
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