The Aves are the bird class of Craniates. They are similar to the reptiles, but are warm-blooded vertebrates (like the mammals) and have become adapted to flying, although some of the 8700 species cannot fly. Birds have light, hollow bones, a four-chambered heart (as do the mammals), the fore limbs are modified to form wings (a characteristic shared with the bats), and uniquely the body is covered with feathers which are moulted and replaced each year. Unlike mammals birds lay calcareous eggs, the number varying with the species from one to twenty or more. The Aves class is a very large class of animals and is subdivided into two subclasses, the Archaeornithes containing the most primitive birds which are closely related to the reptiles, and the Neornithes containing the more advanced birds. The Neornithes are again divided into four major divisions: the Odontognathae, or toothed birds; the Ichthyornithes which are all fossil forms with vertebrae like those of fish; the Impennes containing the penguins; and the
Neognathae which a more specialized modern type of palatal structure. These divisions are further subdivided into orders, sub-orders and families. Research Aves
Diplodocus was a dinosaur of the family Diplodocids or the late Jurassic period. Remains of Diplodocus were first discovered in the 19th century, with more skeletons discovered around 1900 in the western USA. Diplodocus was a herbivore, about 27 metres long with a long neck - formed from fifteen vertebrae - and a long tail that was whip-like at the end and formed of about 73 vertebrae. Diplodocus walked on four, pillar-like legs, the inner toes of which were furnished with long claws. Research Diplodocus
The Elasmobranchs (Elasmobranchii) is an order of fishes, including the sharks, dog-fishes, rays, and chimsera, in which the skull is not composed of distinct bones, but simply forms a kind of cartilaginous box, the vertebral column sometimes cartilaginous, sometimes consisting of distinct vertebrae, the integumentary skeleton in the form of placoid scales, the intestine being very short, and provided with a spiral valve. They have two pairs of fins (pectorals and ventrals), corresponding to the fore and hind limbs, and the ventral fins are close to the anus. The heart consists of an auricle, a ventricle, and a muscular arterial bulb. The gills are fixed, and form a number of pouches, which open internally into the pharynx, communicating outwardly by a series of apertures placed on the side of the neck. Research Elasmobranchs
Homalocephale was a dinosaur of the Cretaceous period. It was about three metres long, walked on its hind legs standing about 130 cm tall and had a flat head with a thickened roof to the skull covered with pits and bony knobs. Broad hip bones, loosely attached to the vertebrae suggest that Homalocephale may have given birth to live young, rather than to eggs. Research Homalocephale
Mamenchisaurus was a dinosaur of the Jurassic period. Mamenchisaurus was a huge animal, 22 metres long with a very long neck and tail, and a herbivore related to Apatosaurus. Prior to 1972 Mamenchisaurus was known from partial skeletons, then in 1972 an almost complete specimen was discovered which revealed the true extent of the long neck which was 11 metres long with 19 vertebrae in it - the longest neck of any known animal, ever. Research Mamenchisaurus
Noasaurus was a dinosaur of the Cretaceous period. Noasaurus is known from a few remains found in the 1970's which comprise a skull, some vertebrae and two foot bones, one of which has a hooked claw with a pit for a muscle to attach. It is thought from these remains that Noasaurus was a carnivore, about 240 centimetres long, and walked on its hind legs. Research Noasaurus
Pteranodon was a dinosaur of the family Pteranodontidae, of the mid to late Cretaceous period. A pterosaur (flying dinosaur) remains have been found in Kansas, North America. There wera number of species, Pteranodon ingens had a wing span of seven meters, Pteranodon sternbergi was larger. Pteranodon is distinguished by a large crest upon the back of the head, a short neck and powerful but short cervical vertebrae. The jaws were long, pointed and toothless. It is generally thought that Pteranodon fed on fish. Research Pteranodon
Pterodactylus was a dinosaur of the family Pterodactylidae, of the late Jurassic period. Remains of Pterodactylus have been found in Europe and East Africa, but only rarely. There were various species of Pterodactylus with wing spans up to about 50 cm - with one species reaching a wing span of 250 cm, and all characterised by a short tail consisting of a few small caudal vertebrae, and having a long, elongated beak. It is likely that Pterodactylus fed on insects and small fish. Research Pterodactylus
Rhamphorhynchus was a dinosaur of the family Rhamphorhynchidae, of the mid to late Jurassic period. Rhamphorhynchus was a pterosaur which hade evolved from earlier, similar dinosaurs over 70 million years. Rhamphorhynchus was a long-tailed flying dinosaur, various species have been identified with wing spans of between 40 cm and 175 cm, their remains having been found in Europe and East Africa. The skull of Rhamphorhynchus was large, elongated and with a pointed front end. The neck was short and compact, comprised of short vertebrae. The jaws were furnished with long, pointed teeth that curved forwards and outwards indicating they were used to catch moving prey. The arms were highly modified as wings, and an adaptation in the wrist supported a membrane which ran across to the neck and may have prevented the animal from stalling in low speed flight. Research Rhamphorhynchus
A snake is an elongated, limbless reptile of the suborder Serpentes of the order Squamata. Because of their 160 to 435 vertebrae, snakes are extremely flexible in their movements.
Snakes crawl along with their belly scales by pushing bends in their body against the surface over which they are moving. The tail is usually quite short, while the head is either indistinctly or clearly delineated from the body. Most snakes kill their prey either by suffocation (the constrictors) or by injecting venom (Venomous snakes), and then waiting for the prey to die, following it by scent. Smooth prey such as new-born mice, fish, amphibians and earthworms are swallowed alive. Snakes can dislocate their bottom jaw from the top, which combined with a bulging windpipe and 'floating ribs' enables them to swallow large prey. Research Snake
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Aves
