Crown groupIn phylogenetics, the crown group, crown clade, or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. It is thus a way of defining a clade, a group consisting of a species and all its extant or extinct descendants.
MammalClass of animals with milk-producing glandsA mammal (from Latin mamma 'breast') is a vertebrate animal of the classMammalia (). 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.
MorganucodontaMorganucodonta ("Glamorganteeth") is an extinct order of basal Mammaliaformes, a group including crown-groupmammals (Mammalia) and their close relatives. Their remains have been found in Southern Africa, Western Europe, North America, India and China. The morganucodontans were probably insectivorous and nocturnal, though like eutriconodonts some species attained large sizes and were carnivorous.
Most recent common ancestorA most recent common ancestor (MRCA), also known as a last common ancestor (LCA) or concestor (a term coined by Nicky Warren), is the most recent individual from which all organisms of a set are inferred to have descended. The most recent common ancestor of a higher taxon is generally assumed to have been a species. The term is also used in reference to the ancestry of groups of genes (haplotypes) rather than organisms.
CladeIn biology, a clade () (from Ancient Greekκλάδος (kládos)'branch'), also known as a monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach to taxonomy adopted by most biological fields. The common ancestor may be an individual, a population, or a species (extinct or extant).
TetrapodA tetrapod (; from Ancient Greek (tetra)'four' and (poús)'foot') is any vertebrateanimal of the cladeTetrapoda (). The main diagnostic and defining trait (synapomorphy) of tetrapods is having four limbs, connected to the shoulder- and pelvic girdles, for which the group is named. As a clade, Tetrapoda is defined such that it includes every organism which descended from four-limbed ancestors, including those which have lost some or all of these limbs, e.g. snakes.
ProbainognathiaProbainognathia is one of the two major subgroups of the clade Eucynodontia, the other being Cynognathia. The earliest forms were carnivorous and insectivorous, though some groups eventually also evolved herbivorous diets. The earliest and most basal probainognathian is the Middle Triassic (Anisian) aged Lumkuia, from South Africa, though probainognathians would not become prominent until the mid Norian stage of the Late Triassic.
ExtinctionTermination of a species' lineageThe thylacine (Thylacinus cynocephalus) is an example of a recently extinct species.Palaeotherium is an example of an extinct genus that is only recorded from fossil records before the existence of hominids.Extinction is the termination of a species via the death of its last member. A taxon may become functionally extinct before the death of its last member if it loses the capacity to reproduce and recover.
SynapsidaClade of tetrapodsSynapsida is a diverse group of tetrapodvertebrates 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.
Adaptive radiationIn evolutionary biology, adaptive radiation is a process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, alters biotic interactions or opens new environmental niches. Starting with a single ancestor, this process results in the speciation and phenotypic adaptation of an array of species exhibiting different morphological and physiological traits.
Late TriassicSubdivision of the Triassic according to the ICS, as of 2024.Vertical axis scale: Millions of years agoEtymologyChronostratigraphic nameUpper TriassicGeochronological nameLate TriassicName formalityFormalUsage informationCelestial bodyEarthRegional usageGlobal (ICS)Time scale(s) usedICS Time ScaleDefinitionChronological unitEpochStratigraphic unitSeriesTime span formalityFormalLower boundary definitionFAD of the AmmoniteLower boundary GSSP, Dolomites, Italy46°31′37″N11°55′49″E / 46.5269°N 11.9303°E / 46.5269; 11.9303Lower GSSP ratified2008Upper boundary definitionFAD of the Ammonite Psiloceras spelae tirolicumUpper boundary GSSPKuhjoch section, Karwendel mountains, Northern Calcareous Alps, Austria47°29′02″N11°31′50″E / 47.4839°N 11.5306°E / 47.4839; 11.5306Upper GSSP ratified2010The Late Triassic is the third and final epoch of the TriassicPeriod in the geologic time scale, spanning the time between 237 Ma and 201.4 Ma (million years ago).
CynodontiaCynodontia (from Ancient Greek κύων (kúōn) 'dog' and ὀδούς (odoús) 'tooth') is a clade of eutheriodont therapsids that first appeared in the Late Permian (approximately 260 mya), and extensively diversified after the Permian–Triassic extinction event. Mammals are cynodonts, as are their extinct ancestors and close relatives (Mammaliaformes), having evolved from advanced probainognathian cynodonts during the Late Triassic.*As an Amazon Associate I earn from qualifying purchases.