The Eagle Evolution

by Barry Williams and Ashley Powell

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COMPSOGNATHUS

For decades, Compsognathus were famed as the smallest dinosaurs known; the first specimen collected was around 1 m (3.3 ft) in length. However, dinosaurs discovered later, such as Caenagnathasia,Microraptor and Parvicursor, were even smaller. The largest Compsognathus specimen is estimated to have weighed somewhere between 0.83 and 3.5 kg (between 1.8 and 7.7 lb).

The lower jaw was slender and had no mandibular fenestra, a hole in the side of the lower jawbone commonly seen in archosaurs. The teeth were small but sharp, suited for its diet of small vertebrates and possibly other small animals, such as insects.

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VELOCIRAPTOR

Velociraptor, like other dromaeosaurids, had a large manus ('hand') with three strongly curved claws, which were similar in construction and flexibility to the wing bones of modern birds.  The structure of the  carpal (wrist) bones prevented pronation of the wrist and forced the 'hands' to be held with the parmal surface facing inwards (medillay), not downwards. The first digit of the foot, as in other theropods, was a small dewclaw .It bore a relatively large, sickle-shaped claw, typical of dromaeosaurid and tromodid dinosaurs. This enlarged claw, which could be over 6.5 cm (2.6 in) long around its outer edge, was most likely a predatory device used to tear into prey, possibly delivering a fatal blow it was discoverd in asia.

SINORNITHOSAURUS: Specimens of Sinornithosaurus have preserved impressions of feathers both covering the entirety of the body and forming the wings. These feathers were indistinguishable in form from those found on birds from the same geological deposits. The body (contour) feathers were generally between 3-4.5 cm long and included two types: the first type are formed of several filaments joined together into "tufts", similar to modern down feathers. The second type, including those on the arms, were composed of rows of filaments (barbs) . Some scientists have suggested that the feathers might have been allowedSinornithosaurus to glide for short distances after leaping from trees

In 2009, a team of scientists led by Empu Gong examined a well-preserved Sinornithosaurus skull, and noted several features suggesting it was the first-identified venomous dinosaur.

However, in 2010, another team of scientists led by Federico Gianechini published a paper casting doubts on the claim that Sinornithosaurus was venomous. They noted that grooved teeth are not unique to this genus, and in fact grooved teeth are found in many other theropods, including other dromaeosaurids .

Oviraptor philoceratops is known from a single partial skeleton (specimen number AMNH 6517), as well as a nest of about fifteen eggs that have been referred to this species (AMNH 6508).

When living, Oviraptor was one of the most bird-like of the non-avian dinosaurs. Its rib cage, in particular, displayed several features that are typical of birds, including a set of processes on each rib that would have kept the rib cage rigid. A relative of Oviraptor called Nomingia was found with a pygostyle, which is a set of fused vertebrae that would later help support the tail feathers of birds. Skin impressions from more primitive oviraptorosaurs, like Caudipteryx and Protarchaeopteryx, clearly show an extensive covering of feathers on the body, feathered wings and feathered tail fans. specimens implies the use of feathered wings to cover the eggs. Given the close anatomical similarity between these species and Oviraptor, it is highly likely that Oviraptor had feathers as well. On the other hand, there is one problem with the use of feathers to "brood" eggs. Since feather is good insulation, heat cannot easily transfer between the body of an animal and the eggs, if there is feather in between them. in was dicoverd in south america

Phorusrhacids, colloquially known as terror birds, are an extinct clade of large carnivorous flightless birds that were the largest species of apex predators in South America during the Cenozoic, 62–2 million years (Ma) ago.

They were roughly 1–3 metres (3.3–9.8 ft) tall. Their closest modern-day relatives are believed to be the 80 cm-tall seriemas. Titanis walleri, one of the larger species, is known from Texas and Florida in North America. Migrating north during the Great American Interchange (which occurred after the volcanic Isthmus of Panama land bridge rose ca. 3 Ma ago). Survival more recently than 1.8 Ma ago. discovered in Patagonia in 2006, represents the largest bird skull yet found. The fossil has been described as being a 71 cm (28 in), nearly intact skull. The beak is roughly 46 cm (18 in) long and curves in a hook shape that resembles an eagle's beak. Most species described as phorusrhacid birds were smaller, 60–90 cm (2.0–3.0 ft) tall, but the new fossil belongs to a bird that probably stood about 3 m (9.8 ft) tall. Scientists theorize that the large terror birds were extremely nimble and quick runners able to reach speeds of 48 km/h (30 mph).

Haast's Eagles were the largest known true raptors, slightly larger even than the largest living vultures. Female eagles are significantly larger than males. Most estimates place the female Haast Eagles in the range of 10–15 kg (22–33 lb) and males around 9–12 kg (20–26 lb). A comparison to living eagles of the Australasian region resulted in estimated masses in Haast's Eagles of 11.5 kg (25 lb) for males and 14 kg (31 lb) for females. One source estimates that the largest females could have scaled more than 16.5 kg (36 lb) in mass. This wingspan is broadly similar to the larger range of female size in some extant eagles: the Wedge-tailed Eagles (Aquila audax), Golden Eagles (A. chrysaetos), Steppe Eagles (A. nipalensis), Martial Eagles (Polemaetus bellicosus) and Steller's Sea Eagles (Haliaeetus pelagicus). However, even the largest extant eagles, none of which are verified to exceed 9 kg (20 lb) in a wild state, are about forty percent smaller in body size than Haast's Eagles. Several of the largest extantOld World vultures, if not in mean mass or other linear measurements, probably exceeded Haast's Eagle in average wingspan.

The upper side of the Harpy Eagle is covered with slate black feathers, and the underside is mostly white, except for the feathered tarsi, which are striped black. There is a broad black band across the upper breast, separating the gray head from the white belly. The head is pale grey, and is crowned with a double crest. The upper side of the tail is black with three gray bands, while the underside of it is black with three white bands. Female Harpy Eagles typically weigh 6 to 9 kg (13 to 20 lb). One source states that adult females can weigh up to 10 kg (22 lb). An exceptionally large captive female, "Jezebel", weighed 12.3 kg (27 lb).  The male, in comparison, is much smaller and weighs only about 4 to 4.8 kg (8.8 to 10.6 lb). Harpy Eagles are 86.5–107 cm (2 ft 10 in–3 ft 6 in) long  and have a wingspan of 176 to 224 cm (5 ft 9 in to 7 ft 4 in).  Among the standard measurements, the wing chord measures 54–63 cm (1 ft 9 in–2 ft 1 in), the tail measures 37–42 cm (1 ft 3 in–1 ft 5 in), the tarsus is 11.4–13 cm (4.5–5.1 in) long and the exposed  culmen from the cere is 4.2 to 6.5 cm (1.7 to 2.6 in).

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