Post by DinosaurMichael on Jul 11, 2012 6:35:42 GMT -5
Marsupial Lion - Thylacoleo carnifex
The Marsupial Lion (Thylacoleo carnifex, the "murderous (or 'meat-cutting') marsupial lion" from thylakos - pouch, leo - lion, carnifex - murderer, tormentor, 'butcher') is an extinct species of carnivorous marsupial mammal that lived in Australia from the early to the late Pleistocene (1,600,000–46,000 years ago). Despite its name it is not closely related to the lion, but is a member of the order Diprotodontia. The Marsupial Lion is the largest meat-eating mammal known to have ever existed in Australia, and one of the largest marsupial carnivores from anywhere in the world (although see Thylacosmilus and Borhyaena). Individuals ranged up to around 75 cm (29.5 in) high at the shoulder and about 150 cm (60 in) from head to tail. Measurements taken from a number of specimens show that they averaged 100 to 130 kg (220 to 285 lb) in weight although individuals heavier than 160 kg (350 lb) may not have been uncommon. This would make it quite comparable to female lions and tigers in general size. The animal was extremely robust with powerfully built jaws and very strong forelimbs. It possessed retractable claws, a unique trait among marsupials. This would have allowed the claws to remain sharp by protecting them from being worn down on hard surfaces. The claws were well-suited to securing prey and for climbing trees. The first digits ("thumbs") on each hand were semi-opposable and bore an enlarged claw. Palaeontologists believe that this would have been used to grapple with and slash at its intended prey as well as providing it with a sure footing on tree trunks and branches. The hind feet had four functional toes, the first digit being much reduced in size but possessing a roughened pad similar to that of possums, which may have assisted with climbing. It is unclear whether the Marsupial Lion exhibited syndactyly (fused second and third toes) like other diprotodonts. The Marsupial Lion's hindquarters were also well-developed although to a lesser extent than the front of the animal. Remains of the animal show that it had a relatively thick and strong tail and that the vertebrae possessed chevrons on their undersides where the tail would have contacted the ground. These would have served to protect critical elements such as nerves and blood vessels if the animal used its tail to support itself when on its hind legs, much like present day kangaroos do. Taking this stance would free up its forelimbs to tackle or slash at its intended victim.
Deinonychus - Deinonychus antirrhopus
Deinonychus ( /daɪˈnɒnɨkəs/ dy-non-i-kəs; Greek: äåéíüò, 'terrible' and ὄíõî, genitive ὄíõ÷ïò 'claw') was a genus of carnivorous dromaeosaurid dinosaur. There is one described species, Deinonychus antirrhopus. This 3.4 meter (11 ft) long dinosaur lived during the early Cretaceous Period, about 115–108 million years ago (from the mid-Aptian to early Albian stages). Fossils have been recovered from the U.S. states of Montana, Wyoming, and Oklahoma, in rocks of the Cloverly Formation and Antlers Formation, though teeth that may belong to Deinonychus have been found much farther east in Maryland. Paleontologist John Ostrom's study of Deinonychus in the late 1960s revolutionized the way scientists thought about dinosaurs, leading to the "dinosaur renaissance" and igniting the debate on whether dinosaurs were warm-blooded or cold blooded. Before this, the popular conception of dinosaurs had been one of plodding, reptilian giants. Ostrom noted the small body, sleek, horizontal posture, ratite-like spine, and especially the enlarged raptorial claws on the feet, which suggested an active, agile predator. "Terrible claw" refers to the unusually large, sickle-shaped talon on the second toe of each hind foot. The fossil YPM 5205 preserves a large, strongly curved ungual. In life, archosaurs have a horny sheath over this bone which extends the length. Ostrom looked at crocodile and bird claws and reconstructed the claw for YPM 5205 as over 120 millimetres (4.7 in) long. The species name antirrhopus means “counter balance”, which refers to Ostrom's idea about the function of the tail. As in other dromaeosaurids, the tail vertebrae have a series of ossified tendons and super-elongated bone processes. These features seemed to make the tail into a stiff counterbalance, but a fossil of the very closely related Velociraptor mongoliensis (IGM 100/986) has an articulated tail skeleton that is curved laterally in a long S–shape. This suggests that, in life, the tail could bend to the sides with a high degree of flexibility. Based on the largest known specimens, Deinonychus could reach at least 3.4 metres (11 ft 2 in) in length, with a skull length of 410 mm (16.1 in), a hip height of 0.87 metres (2 ft 10 in), and an estimated weight of 73 kilograms (160 lb). Its skull was equipped with powerful jaws lined with around seventy curved, blade-like teeth. Studies of the skull have progressed a great deal over the decades. Ostrom reconstructed the partial, imperfectly preserved, skulls that he had as triangular, broad, and fairly similar to Allosaurus. Additional Deinonychus skull material and closely related species found with good three-dimensional preservation show that the palate was more vaulted than Ostrom thought, making the snout far narrower, while the jugals flared broadly, giving greater stereoscopic vision. The skull of Deinonychus was different from that of Velociraptor, however, in that it had a more robust skull roof like that of Dromaeosaurus, and did not have the depressed nasals of Velociraptor. Both the skull and the lower jaw had fenestrae (skull openings) which reduced the weight of the skull. In Deinonychus, the antorbital fenestra, a skull opening between the eye and nostril, was particularly large. Deinonychus possessed large hands (manus) with three claws on each forelimb. The first digit was shortest and the second was longest. Each hind foot bore a sickle-shaped claw on the second digit, which was probably used during predation.
The Marsupial Lion (Thylacoleo carnifex, the "murderous (or 'meat-cutting') marsupial lion" from thylakos - pouch, leo - lion, carnifex - murderer, tormentor, 'butcher') is an extinct species of carnivorous marsupial mammal that lived in Australia from the early to the late Pleistocene (1,600,000–46,000 years ago). Despite its name it is not closely related to the lion, but is a member of the order Diprotodontia. The Marsupial Lion is the largest meat-eating mammal known to have ever existed in Australia, and one of the largest marsupial carnivores from anywhere in the world (although see Thylacosmilus and Borhyaena). Individuals ranged up to around 75 cm (29.5 in) high at the shoulder and about 150 cm (60 in) from head to tail. Measurements taken from a number of specimens show that they averaged 100 to 130 kg (220 to 285 lb) in weight although individuals heavier than 160 kg (350 lb) may not have been uncommon. This would make it quite comparable to female lions and tigers in general size. The animal was extremely robust with powerfully built jaws and very strong forelimbs. It possessed retractable claws, a unique trait among marsupials. This would have allowed the claws to remain sharp by protecting them from being worn down on hard surfaces. The claws were well-suited to securing prey and for climbing trees. The first digits ("thumbs") on each hand were semi-opposable and bore an enlarged claw. Palaeontologists believe that this would have been used to grapple with and slash at its intended prey as well as providing it with a sure footing on tree trunks and branches. The hind feet had four functional toes, the first digit being much reduced in size but possessing a roughened pad similar to that of possums, which may have assisted with climbing. It is unclear whether the Marsupial Lion exhibited syndactyly (fused second and third toes) like other diprotodonts. The Marsupial Lion's hindquarters were also well-developed although to a lesser extent than the front of the animal. Remains of the animal show that it had a relatively thick and strong tail and that the vertebrae possessed chevrons on their undersides where the tail would have contacted the ground. These would have served to protect critical elements such as nerves and blood vessels if the animal used its tail to support itself when on its hind legs, much like present day kangaroos do. Taking this stance would free up its forelimbs to tackle or slash at its intended victim.
Deinonychus - Deinonychus antirrhopus
Deinonychus ( /daɪˈnɒnɨkəs/ dy-non-i-kəs; Greek: äåéíüò, 'terrible' and ὄíõî, genitive ὄíõ÷ïò 'claw') was a genus of carnivorous dromaeosaurid dinosaur. There is one described species, Deinonychus antirrhopus. This 3.4 meter (11 ft) long dinosaur lived during the early Cretaceous Period, about 115–108 million years ago (from the mid-Aptian to early Albian stages). Fossils have been recovered from the U.S. states of Montana, Wyoming, and Oklahoma, in rocks of the Cloverly Formation and Antlers Formation, though teeth that may belong to Deinonychus have been found much farther east in Maryland. Paleontologist John Ostrom's study of Deinonychus in the late 1960s revolutionized the way scientists thought about dinosaurs, leading to the "dinosaur renaissance" and igniting the debate on whether dinosaurs were warm-blooded or cold blooded. Before this, the popular conception of dinosaurs had been one of plodding, reptilian giants. Ostrom noted the small body, sleek, horizontal posture, ratite-like spine, and especially the enlarged raptorial claws on the feet, which suggested an active, agile predator. "Terrible claw" refers to the unusually large, sickle-shaped talon on the second toe of each hind foot. The fossil YPM 5205 preserves a large, strongly curved ungual. In life, archosaurs have a horny sheath over this bone which extends the length. Ostrom looked at crocodile and bird claws and reconstructed the claw for YPM 5205 as over 120 millimetres (4.7 in) long. The species name antirrhopus means “counter balance”, which refers to Ostrom's idea about the function of the tail. As in other dromaeosaurids, the tail vertebrae have a series of ossified tendons and super-elongated bone processes. These features seemed to make the tail into a stiff counterbalance, but a fossil of the very closely related Velociraptor mongoliensis (IGM 100/986) has an articulated tail skeleton that is curved laterally in a long S–shape. This suggests that, in life, the tail could bend to the sides with a high degree of flexibility. Based on the largest known specimens, Deinonychus could reach at least 3.4 metres (11 ft 2 in) in length, with a skull length of 410 mm (16.1 in), a hip height of 0.87 metres (2 ft 10 in), and an estimated weight of 73 kilograms (160 lb). Its skull was equipped with powerful jaws lined with around seventy curved, blade-like teeth. Studies of the skull have progressed a great deal over the decades. Ostrom reconstructed the partial, imperfectly preserved, skulls that he had as triangular, broad, and fairly similar to Allosaurus. Additional Deinonychus skull material and closely related species found with good three-dimensional preservation show that the palate was more vaulted than Ostrom thought, making the snout far narrower, while the jugals flared broadly, giving greater stereoscopic vision. The skull of Deinonychus was different from that of Velociraptor, however, in that it had a more robust skull roof like that of Dromaeosaurus, and did not have the depressed nasals of Velociraptor. Both the skull and the lower jaw had fenestrae (skull openings) which reduced the weight of the skull. In Deinonychus, the antorbital fenestra, a skull opening between the eye and nostril, was particularly large. Deinonychus possessed large hands (manus) with three claws on each forelimb. The first digit was shortest and the second was longest. Each hind foot bore a sickle-shaped claw on the second digit, which was probably used during predation.