This study contributes to a better understanding of the mechanisms that underlie the evolution of the platypus genome, might extend the less-is-more evolutionary model to monotremes, and provides novel insights into the importance of gene loss events during mammalian evolution.ДЄ major goal in the sequencing of different genomes is to identify the genetic changes that are responsible for the physiological differences between these organisms. The observed loss of genes involved in gastric functions might be responsible for the anatomical and physiological differences in gastrointestinal tract between monotremes and other vertebrates, including small size, lack of glands, and high pH of the monotreme stomach. All of these genes are highly conserved in vertebrates, reflecting a unique pattern of evolution in the platypus genome not previously seen in other mammalian genomes. Other genes implicated in gastric functions, such as the ОІ subunit of the H +/K +-ATPase and the aspartyl protease cathepsin E, have been inactivated because of the acquisition of loss-of-function mutations. These include the aspartyl proteases pepsinogen A and pepsinogens B/C, the hydrochloric acid secretion stimulatory hormone gastrin, and the О± subunit of the gastric H +/K +-ATPase. Comparison with other vertebrate genomes revealed that the main genes implicated in the formation and activity of gastric juice have been lost in platypus. We show that several genes implicated in food digestion in the stomach have been deleted or inactivated in platypus. The platypus genome sequence provides a unique opportunity to illuminate some aspects of the biology and evolution of these animals. Pterosaurs flew in the air and fish, lungfish, crocodiles and marine reptiles, such as long-necked plesiosaurs lived in the oceans.The duck-billed platypus ( Ornithorhynchus anatinus) belongs to the mammalian subclass Prototheria, which diverged from the Theria line early in mammalian evolution. Perhaps these smaller dinosaurs moved in herds like modern antelope, always on the lookout for predators like the carnivorous theropod Rapator ornitholestoides, which reached a length of about 6m. Dinosaurs, including giant long-necked sauropods munched on vegetation along with the 1.5m long Lightning Beast Fulgurotherium australe. Steropodon galmani may have used electroreceptors in its snout to hunt crustaceans in a similar manner to the modern platypus.ДЇossils of other animals living at the time of these ancestral egg-layers have also been found at Lightning Ridge. The Cretaceous monotremes were probably similar in size and shape to the modern platypus, although in modern monotremes the well-developed teeth of the fossil forms are absent. Steropodon, was a fossil monotreme and is one of the ancestors of the modern Platypus and echidnas of Australia and New Guinea. Near the edge of this ancient continent, fragments of the remains of these animals accumulated in the sands of the inland sea. Dinosaurs and their relatives dominated this landscape, as well as our rare and tiny mammal ancestors. Fossil time period: Lightning RidgeДЎ10 million years ago the supercontinent Gondwana was a wilderness of forests of pines, ferns and palms separated by tracts of shallow sea. As well as being beautiful gems, the rare and often valuable fossils from Lightning Ridge have the potential to solve many mysteries about our ancient mammalian ancestors. Without the help of miners, many fossils, including Steropodon and Kollikodon, would never have been recognised. Palaeontologists searching for fossils of dinosaurs and primitive mammals at Lightning Ridge consult with opal miners to see what they have found, or obtain permission to sift through spoil heaps and excavate in opal mines. In Australia Cretaceous mammal fossils are almost unknown, which is why the Lightning Ridge fossils are so important. Mammal fossils are not often found in Cretaceous fossil deposits, since the generally rare, tiny and delicate mammals of this period were far outnumbered by the more successful and diverse dinosaurs. The most famous and significant fossils from Lightning Ridge are those of some early mammals. As they tunnel through these sediments searching for precious opal, miners sometimes find these fossils. The sandstone at Lightning Ridge once formed the floor of an ancient shallow inland sea where plants, aquatic life and occasionally the bones and teeth of animals were preserved. Deposits at Lightning Ridge yield some of the rarest, most beautiful and precious fossils in the world.

Platypus evolution gems