Concept
Crown group
Related concepts (23)
Amniote
Amniotes belong to the clade Amniota, a clade of tetrapod vertebrates that comprises sauropsids (including all reptiles and birds) and synapsids (including mammals and mammal ancestors like "pelycosaurs" and therapsids). They are distinguished from the other living tetrapod clade—the lissamphibians—by the development of three extraembryonic membranes (amnion for embryoic protection, chorion for gas exchange, and allantois for metabolic waste disposal or storage), thicker and more keratinized skin, and costal respiration (breathing by expanding/constricting the rib cage).
Opabinia
Opabinia regalis is an extinct, stem group arthropod found in the Middle Cambrian Burgess Shale Lagerstätte (505 million years ago) of British Columbia. Opabinia was a soft-bodied animal, measuring up to 7 cm in body length, and its segmented trunk had flaps along the sides and a fan-shaped tail. The head shows unusual features: five eyes, a mouth under the head and facing backwards, and a clawed proboscis that probably passed food to the mouth. Opabinia probably lived on the seafloor, using the proboscis to seek out small, soft food.
Crocodilia
Crocodilia (or Crocodylia, both krQk@'dIli@) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 94 million years ago in the Late Cretaceous period (Cenomanian stage) and are the closest living relatives of birds, as the two groups are the only known survivors of the Archosauria. Members of the order's total group, the clade Pseudosuchia, appeared about 250 million years ago in the Early Triassic period, and diversified during the Mesozoic era.
Lungfish
Lungfish are freshwater vertebrates belonging to the class Dipnoi. Lungfish are best known for retaining ancestral characteristics within the Osteichthyes, including the ability to breathe air, and ancestral structures within Sarcopterygii, including the presence of lobed fins with a well-developed internal skeleton. Lungfish represent the closest living relatives of the tetrapods. The mouths of lungfish typically bear tooth plates, which are used to crush hard shelled organisms.
Paleontology
Paleontology (ˌpeɪliɒnˈtɒlədʒi,ˌpæli-,-ən-), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossils to classify organisms and study their interactions with each other and their environments (their paleoecology). Paleontological observations have been documented as far back as the 5th century BC.
Synapsid
Synapsids are one of the two major clades of vertebrate animals that evolved from basal amniotes, the other being the sauropsids, which include reptiles (turtles, crocodilians and lepidosaurs) and birds. The synapsids were once the dominant land animals in the late Paleozoic and early Mesozoic, but the only extant group that survived into the Cenozoic are the mammals. Unlike other amniotes, synapsids have a single temporal fenestra, an opening low in the skull roof behind each eye orbit, leaving a bony arch beneath each; this accounts for their name.
PhyloCode
The International Code of Phylogenetic Nomenclature, known as the PhyloCode for short, is a formal set of rules governing phylogenetic nomenclature. Its current version is specifically designed to regulate the naming of clades, leaving the governance of species names up to the rank-based nomenclature codes (ICN, ICNCP, ICNP, ICZN, ICVCN). The PhyloCode is associated with the International Society for Phylogenetic Nomenclature (ISPN). The companion volume, Phylonyms, establishes 300 taxon names under PhyloCode, serving as examples for those unfamiliar with the code.
Palaeognathae
Palaeognathae (ˌpæliˈɒgnəθi; ) is a infraclass of birds, called paleognaths or palaeognaths, within the class Aves of the clade Archosauria. It is one of the two extant infraclasses of birds, the other being Neognathae, both of which form Neornithes. Palaeognathae contains five extant branches of flightless lineages (plus two extinct clades), termed ratites, and one flying lineage, the Neotropic tinamous.
Burgess Shale
The Burgess Shale is a fossil-bearing deposit exposed in the Canadian Rockies of British Columbia, Canada. It is famous for the exceptional preservation of the soft parts of its fossils. At old (middle Cambrian), it is one of the earliest fossil beds containing soft-part imprints. The rock unit is a black shale and crops out at a number of localities near the town of Field in Yoho National Park and the Kicking Horse Pass. Another outcrop is in Kootenay National Park 42 km to the south.
Euparkeria
Euparkeria (juːˌpɑːrkəˈriːə; meaning "Parker's good animal", named in honor of W. K. Parker) is an extinct genus of archosauriform reptile from the Triassic of South Africa. Euparkeria is close to the ancestry of Archosauria, the reptile group that includes crocodilians, pterosaurs, and dinosaurs (including birds). Fossils of Euparkeria, including nearly complete skeletons, have been recovered from the Cynognathus Assemblage Zone (CAZ, also known as the Burgersdorp Formation), which hosts the oldest advanced archosauriforms in the fossil-rich Karoo Basin.