|
|
Post by Runic on May 26, 2013 19:11:15 GMT 5
 Scientific classification Kingdom: Animalia Phylum: Chordata Class: Aves Order: Falconiformes (or Accipitriformes, q.v.) Family: Accipitridae Genus: Stephanoaetus Species: Stephanoaetus coronatus The Crowned Eagle (Stephanoaetus coronatus), more precisely known as the Crowned Hawk-eagle, is a very large, powerful, crested bird of prey (80-90 cm approx) found in tropical Africa south of the Sahara; in Southern Africa a common resident in suitable habitat in the eastern areas. It inhabits mainly dense forests; its staple diet consists of monkeys (particularly those of the genus Chlorocebus) and other mammals up to 20 kg (44 lb), such as the Cape Hyrax and small antelopes. To a far lesser extent, birds and monitor lizards are also taken, however 98% of the diet is mammalian. While smaller than the Martial Eagle, the Crowned Eagle is renowned as Africa's most powerful and ferocious eagle in terms of the weight and nature of prey taken. Due to their striking similarities, the Crowned Eagle is often considered Africa's analogue of the Harpy Eagle. The Crowned Hawk-eagle is the only extant member of the genus Stephanoaetus. A second species, the Madagascar Crowned Hawk-eagle (Stephanoaetus mahery) became extinct after humans settled on Madagascar (Goodman, 1994). It was the largest and strongest bird of prey of prehistoric Madagascar (see Elephant Bird) and together with the living Fossa (animal) Cryptoprocta ferox, the larger Giant Fossa Cryptoprocta spelea (Goodman et al. 2004) and the two malagasy crocodiles, the living Nile crocodile and the recently extinct giant dwarf crocodile Crocodylus robustus the apex predators on the island. Extinction by overhunting of the giant lemurs which constituted its main prey seems to have been the main reason for this species' disappearance, which took place at some time during the second half of the first millennium AD. |
|
|
|
Post by Runic on May 26, 2013 19:11:35 GMT 5
Face to face: a child killer and its prey
From Jonathan Clayton in Johannesburg
THE African crowned eagle was found guilty yesterday of the murder about two to three million years ago of arguably the most important human ancestor found.
The mystery of how the Taung child, the continent’s first hominid discovery, met its end, aged 3½, has puzzled scientists for decades and could throw important new light on the theory of human evolution.
“This is the end of an 80-year-old murder mystery . . . We have proved conclusively and beyond a reasonable doubt, which would be accepted in a court of law, that the African crowned eagle was the killer,” Lee Berger, an American palaeontologist, said.
The end of the mystery “gives us real insight into the past lives of these human ancestors,” he said. “It shows it was not only big cats, but also these creatures from the air — aerial bombardment if you will — that our ancestors had to be afraid of. These were the stressors and stresses that grew and shaped the human mind and formed our behaviour today.”
In 1924 the discovery of the half-ape, half-man fossilised skull about 300 miles (480 kilometres) northwest of Johannesburg overturned the view that humans originated in Eurasia and focused the search for the “cradle of humanity” on Africa.
Announcing the verdict, Professor Berger, a reader in palaeoanthropology at Wits University in Johannesburg, said new evidence showed that the child was not killed by leopards or sabre-toothed cats, the previous suspects.
He said “small punctures and keyhole slots” inside the eye sockets and brain area could not have been made by such large predators.
“Carnivores cannot create that sort of damage,” he told a press conference in the margins of an international conference on the origins of man. “This child was killed by a single blow of a 14cm long talon into the brain . . . It was later disembowelled. The eagle would have used its beak to eat out the eyes and the brain — some of the most nutritious parts — and created these marks.”
The Taung child was discovered by Raymond Dart, a British professor who had recently arrived to take up a new post in South Africa. He published a paper in Nature saying that the child, a specimen of the human ancestor species Australopithecus africanus, was the famed “missing link” between man and ape.
The bold claim was widely dismissed at the time, but subsequently other, older hominids, such as Lucy, believed to be more than three million years old, were found in the Great Rift Valley that snakes across the continent from South Africa through Kenya and Tanzania to Ethiopia.
Professor Berger and Ron Clarke, a fellow palaeontologist, first mooted the theory that the killer was a predatory bird similar to todayÂ’s African crowned eagle about ten years ago.
“The one big problem was the lack of multiple areas of damage that could be linked to a bird of prey,” Professor Berger said. “We had one little flap of bone on the top of the skull that looked like some of the damage we see made by eagles and nothing else. It was the ultimate two-million-year-old cold case!”
Five months ago researchers from Ohio State University submitted what Professor Berger called the most comprehensive study to date of eagle damage on bones. Asked to review the paper for the American Journal of Physical Anthropology, Professor Berger realised that he had stumbled upon his own missing link.
The study on primate remains from modern-day crowned eagle nests in the Tai forest in Ivory Coast showed that raptors routinely hunt primates much larger than themselves by swooping down at speed and piercing their skulls with their back talons.
The Ohio State paper also identified key features that distinguished damage caused by eagles from that of other predators. They include the flaps of depressed bone on top of the skull caused by the birdsÂ’ talons and keyhole-shaped cuts on the side made by their beaks.
They also identified puncture marks and ragged incisions in the base of the eye sockets, made when eagles rip out the eyes of dead monkeys with their talons and beaks.
Professor Berger returned to the skull of the Taung child and noticed a tiny hole and jagged tears at the base of the eye sockets. “I couldn’t believe my eyes, as thousands of scientists, including myself, had overlooked this critical damage. I felt a little bit of an idiot,” he said.
Professor BergerÂ’s research, which has already been reviewed and accepted by experts in the field, is due to be published in the February edition of the prestigious American Journal of Physical Anthropology.
|
|
|
|
Post by Runic on May 26, 2013 19:12:56 GMT 5
Taphonomic Aspects of Crowned Hawk-Eagle Predation on Monkeys
William J. Sandersa*, Josh Trapania,b, John C. Mitanic
This study provides a taphonomic analysis of prey accumulations of crowned hawk-eagles (Stephanoaetus coronatus)
from Ngogo, Kibale National Park, Uganda, collected over 37 months from below nests of two eagle pairs. Crowned
hawk-eagles are powerful predators capable of killing animals much larger than themselves, and are significant
predators of cercopithecoid monkeys in forest habitats throughout sub-Saharan Africa. At Ngogo, 81% of the
individuals in the kill sample are monkeys. Redtail monkeys (Cercopithecus ascanius) are particularly well represented
in the sample, making up 66% of monkeys identified to species. Despite an impressive killing apparatus, crowned
hawk-eagles are fastidious eaters that inflict far less damage to bone than mammalian predators. Examination of
skeletal material from the Ngogo kill sample reveals that crania, hindlimb elements, and scapulae survive predation
better than do other bones. Crania of adults are typically complete and accompanied by mandibles, while crania of
young individuals are usually dissociated from mandibles and lack basicrania and faces. Long bones are often whole or
show minimal damage. Thin bones, such as crania and innominates, are marked by numerous nicks, punctures, and
“can-opener” perforations. Scapular blades are heavily raked and shattered. Along with the strong preference for
cercopithecoids, these distinct patterns of bone survival and damage indicate the feasibility of recognizing specific
taphonomic signatures of large raptors in fossil assemblages.
Berger and Clarke (1995) hypothesized that crowned hawk-eagles or similar large raptors were principally
responsible for the accumulation of the late Pliocene fossil fauna from Taung, South Africa, including the type infant
skull of Australopithecus africanus. The results of our study suggest that the faunal composition and type of damage to
the hominid skull and other bone from Taung are consistent with the predatory activities of large raptors. More
rigorous assessment of their hypothesis will require sorting the Taung fauna by locality and further detailed analysis of
species composition and bone damage and survivability patterns.
|
|
