Mesozoic and Tertiary Fossil Mammals and Birds of Great Britain. Birds and mammals are important animal groups today, and the most conspicuous part of the modern fauna.
The mammals originated in the Triassic Period, part of the Mesozoic Era, over 225 million years (Ma) ago, and the first birds arose i n the Jurassic Period, over 150 Ma. The fossil record of the early Mesozoic mammals of the Triassic, Jurassic and Cretaceous periods is particularly good in Great Britain, representing well the early radiations of the initially small forms. For the first 160 Ma of their history, nearly all of the mammals were smaller than domestic cats, and most were shrew-sized. And yet they diversified considerably at the feet of the contemporaneous dinosaurs. The record of Mesozoic birds in Britain is much poorer. After the K–T (Cretaceous ['K']–Tertiary) mass extinction of 65 Ma, major changes occurred in the life on Earth. V32chap1Part2. V32chap1Part1.
Life Before Dinosaurs - Natural History And Fossils. What Are Life Before Dinosaurs?
Life before dinosaurs are creatures that existed before the Mesozoic era (see what are dinosaurs?) The creatures first evolved about 600 million years ago. The time life before dinosaurs inherit is called the Palaeozoic era. Even further back is the Precambrian, not much life at all. In the Palaeozoic era there are 6 periods.
The Cambrian (543-490 MYA) And The Ordovican (490-443 MYA) The Cambrian- The Cambrian was one of the first time periods to have life (not including bacteria). The Silurian (443-417 MYA) And The Devonian (417-354 MYA) The Silurian- The Silurian was an important part of the Earths history as it is the period when life (plants and animals) first crawled out onto land. The Carboniferous (354-290 MYA) And The Permian (290 - 248) The Carboniferous- This period was perhaps the hottest, wettest and most humid period in history. Image- Meganeura. Permian. The Permian witnessed the diversification of the early amniotes into the ancestral groups of the mammals, turtles, lepidosaurs and archosaurs.
The world at the time was dominated by a single supercontinent known as Pangaea, surrounded by a global ocean called Panthalassa. The extensive rainforests of the Carboniferous had disappeared, leaving behind vast regions of arid desert within the continental interior. Reptiles, who could better cope with these drier conditions, rose to dominance in lieu of their amphibian ancestors. The Permian Period (along with the Paleozoic Era) ended with the largest mass extinction in Earth's history, in which nearly 90% of marine species and 70% of terrestrial species died out.[6] It would take well into the Triassic for life to recover from this catastrophe.
Discovery[edit] Key events in the Permian An approximate timescale of key Permian events. The term "Permian" was introduced into geology in 1841 by Sir R. ICS Subdivisions[edit] Oceans[edit] Climate[edit] Prehistoric Life During the Permian Period. The Permian period was, literally, a time of beginnings and endings.
It was during the Permian that the therapsids, or "mammal-like reptiles," first appeared--and a branch of therapsids spawned the very first mammals of the ensuing Triassic period. However, the end of the Permian witnessed the most severe mass extinction of life in the history of the planet, even worse than the one that doomed the dinosaurs tens of millions of years later. The Permian was the last period of the Paleozoic Era (542-250 million years ago), preceded by the Cambrian, Ordovician, Silurian, Devonian and Carboniferous periods. Climate and geography. As during the preceding Carboniferous period, the climate of the Permian period was intimately linked with its geography. Terrestrial Life During the Permian Period Reptiles. Amphibians. Insects.