leniwce-i-pancerniki: Evolution of mammals

Evidence: 100 • authority: 72

The evolution of mammals has passed through many stages since the first appearance of their synapsid ancestors in the Pennsylvanian sub-period of the late Carboniferous period. By the mid-Triassic, there were many synapsid species that looked like mammals. The lineage leading to today's mammals split up in the Jurassic; synapsids from this period include Dryolestes, more closely related to extant placentals and marsupials than to monotremes, as well as Ambondro, more closely related to monotremes. Later on, the eutherian and metatherian lineages separated; the metatherians are the animals more closely related to the marsupials, while the eutherians are those more closely related to the plac…

Evidence: 67 • authority: 72

The Carboniferous ( KAR-bə-NIF-ər-əs) is a geologic period and system of the Paleozoic era that spans 60 million years, from the end of the Devonian Period 358.86 Ma (million years ago) to the beginning of the Permian Period, 298.9 Ma. It is the fifth period of the Phanerozoic eon. In North America, the Carboniferous is often treated as two separate geological periods, the earlier Mississippian and the later Pennsylvanian. The name Carboniferous means "coal-bearing", from the Latin carbō ("coal") and ferō ("bear, carry"), and refers to the many coal beds formed globally during that time. The first of the modern "system" names, it was coined by geologists William Conybeare and William Philli…

Evidence: 54 • authority: 88

Evidence: 54 • authority: 72

A mammal (from Latin mamma 'breast') is a vertebrate animal of the class Mammalia (). Mammals are characterized by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three middle ear bones. These characteristics distinguish them from reptiles and birds, from which their ancestors diverged in the Carboniferous period over 300 million years ago. Around 6,640 extant species of mammals have been described and divided into 27 orders. The study of mammals is called mammalogy. The largest orders of mammals, by number of species, are the rodents, bats, and eulipotyphlans (including hedgehogs, moles and shrews). The next thr…

Evidence: 54 • authority: 92

An early Pangaean vicariance model for synapsid evolution.. Genetic isolation due to geographic separation (vicariance) is the best understood cause of vertebrate speciation. Nevertheless, it has never been demonstrated in the fossil record across a wide range of taxa. Here, by reviewing in-depth the available data of the Late Palaeozoic (~ 350-250 million years ago), I reconstructed an early Pangaean junction-disjunction palaeogeographic model and showed that it coincides strongly with time-calibrated cladograms of the Late Palaeozoic synapsids (the primitive ancestors of modern mammals). The temporal development of the vicariant topology seems to fit closely with the emergence rhythm of t…

Evidence: 54 • authority: 72

Evidence: 54 • authority: 72

The Carboniferous rainforest collapse (CRC) was a minor extinction event that occurred around 305 million years ago in the Carboniferous period. The event occurred at the end of the Moscovian and continued into the early Kasimovian stages of the Pennsylvanian (Upper Carboniferous). It altered the vast coal forests that covered the equatorial region of Euramerica (Europe and North America). This event may have fragmented the forests into isolated refugia or ecological "islands", which in turn encouraged dwarfism and, shortly after, extinction of many plant and animal species. Following the event, coal-forming tropical forests continued in large areas of the Earth, but their extent and compos…

Evidence: 48 • authority: 88

Evidence: 48 • authority: 92

Early Origins of Divergent Patterns of Morphological Evolution on the Mammal and Reptile Stem-Lineages.. The origin of amniotes 320 million years ago signaled independence from water in vertebrates and was closely followed by divergences within the mammal and reptile stem lineages (Synapsida and Reptilia). Early members of both groups had highly similar morphologies, being superficially "lizard-like" forms with many plesiomorphies. However, the extent to which they might have exhibited divergent patterns of evolutionary change, with the potential to explain the large biological differences between their living members, is unresolved. We use a new, comprehensive phylogenetic dataset to quant…

Evidence: 42 • authority: 80

Evidence: 42 • authority: 72

Pelycosaur ( PEL-ih-kə-sor) is an older term for basal or primitive Late Paleozoic synapsids, excluding the therapsids and their descendants. Previously, the term mammal-like reptile was used, and Pelycosauria was considered an order, but this is now thought to be incorrect and outdated. The terms stem mammals, protomammals, and basal or primitive synapsids are instead used where needed. Because Pelycosaur excludes its own descendants, the advanced synapsid group Therapsida, the term is paraphyletic and contrary to modern formal naming practice. Thus the name pelycosaurs, similar to the term mammal-like reptiles, fell out of favor among scientists by the 21st century, and is only used infor…

Evidence: 36 • authority: 72

Synapsida is a diverse group of tetrapod vertebrates that includes all mammals and their extinct relatives. It is one of the two major clades of the group Amniota, the other being the more diverse group Sauropsida (which includes all extant reptiles and birds). Synapsids have a single lower temporal fenestra, an opening low in the skull roof behind each eye socket. These openings create a bony arch that allows for the attachment of larger jaw muscles and a more efficient bite. While previously argued to be distinctive to synapsids, single temporal fenestrae are also found in many primitive sauropsids. It has recently been argued that the last common ancestor of synapsids and sauropsids shar…