taxon_rank lepospondyli
Adelospondyli is an ___MASK80___ of elongate , presumably aquatic , Carboniferous amphibians . The skull is solidly roofed , and elongate , with the orbits located very far forward . The limbs are well developed . Most adelospondyls belong to the ___MASK82___ Adelogyrinidae , although the adelospondyl " Acherontiscus " has been placed in its own ___MASK82___ , Acherontiscidae . The group is restricted to the Mississippian ( Serpukhovian Age ) of Scotland . Anatomy is the ___MASK39___ of biology concerned with the study of the structure of organisms and their parts . Anatomy is inherently tied to embryology , comparative anatomy , evolutionary biology , and phylogeny , as these are the processes by which anatomy is generated over immediate ( embryology ) and long ( evolution ) timescales . Human anatomy is one of the basic essential sciences of medicine . Salamanders are a ___MASK98___ of amphibians typically characterized by a lizard - like appearance , with slender bodies , blunt snouts , short limbs projecting at right angles to the body , and the presence of a tail in both larvae and adults . All present - day salamander families are grouped together under the scientific name Urodela . Salamander diversity is most abundant in the Northern Hemisphere and most ___MASK88___ are found in the Holarctic ecozone , with some ___MASK88___ present in the Neotropical zone . In animal anatomy , the notochord is a flexible rod made out of a material similar to cartilage . If a ___MASK88___ has a notochord , it is , by definition , a chordate . The notochord lies along the anteroposterior (" head to tail ") axis , is usually closer to the dorsal than the ventral surface of the animal , and is composed of cells derived from the mesoderm . The notochord has been observed to have many functions including developmental functions . The most commonly cited functions are as a site of muscle attachment , vertebral precursor , and as a midline tissue that provides signals to the surrounding tissue during development . The Silurian is a geologic period and system spanning 24 . 6 million years from the end of the Ordovician Period , at million years ago ( Mya ), to the beginning of the Devonian Period , Mya . As with other geologic periods , the rock beds that define the period ' s start and end are well identified , but the exact dates are uncertain by several million years . The base of the Silurian is set at a major Ordovician - Silurian extinction event when 60 % of marine ___MASK88___ were wiped out . Animals are multicellular , eukaryotic organisms of the ___MASK46___ Animalia ( also called Metazoa ). The animal ___MASK46___ emerged as a basal clade within Apoikozoa as a sister of the choanoflagellates . Sponges are the most basal clade of animals . Animals are motile , meaning they can move spontaneously and independently at some point in their lives . Their body plan eventually becomes fixed as they develop , although some undergo a process of metamorphosis later in their lives . All animals are heterotrophs : they must ingest other organisms or their products for sustenance . Morocco (', lit . " The West "; '), officially known as the ___MASK46___ of Morocco (', lit . " The Western ___MASK46___ "; '), is a sovereign country located in the Maghreb region of North Africa . Geographically , Morocco is characterized by a rugged mountainous interior , large tracts of desert , and a lengthy coastline along the Atlantic Ocean and Mediterranean Sea . Scotland ( Scots : ) is a country that is part of the United ___MASK46___ and covers the northern third of the island of Great Britain . It shares a border with England to the south , and is otherwise surrounded by the Atlantic Ocean , with the North Sea to the east and the North Channel and Irish Sea to the south - west . In addition to the mainland , the country is made up of more than 790 islands , including the Northern Isles and the Hebrides . Diplocaulus ( meaning " double caul ") is an extinct ___MASK49___ of lepospondyl amphibians from the Permian period of North America . It is one of the largest lepospondyls , with a distinctive boomerang - shaped skull . Remains attributed to " Diplocaulus " have been found from the Late Permian of Morocco and represent the youngest known occurrence of a lepospondyl . The axolotl ( from ] ) also known as a Mexican salamander (" Ambystoma mexicanum ") or a Mexican walking fish , is a neotenic salamander , closely related to the tiger salamander . Although the axolotl is colloquially known as a " walking fish ", it is not a fish , but an amphibian . The ___MASK88___ originates from numerous lakes , such as Lake Xochimilco underlying Mexico City . Axolotls are unusual among amphibians in that they reach adulthood without undergoing metamorphosis . Instead of developing lungs and taking to land , the adults remain aquatic and gilled . The Turkish Straits are a ___MASK21___ of internationally - significant waterways in northwestern Turkey that connect the Aegean and Mediterranean seas to the Black Sea . Snakes are elongated , legless , carnivorous reptiles of the ___MASK78___ Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears . Like all squamates , snakes are ectothermic , amniote vertebrates covered in overlapping scales . Many ___MASK88___ of snakes have skulls with several more joints than their lizard ancestors , enabling them to swallow prey much larger than their heads with their highly mobile jaws . To accommodate their narrow bodies , snakes ' paired organs ( such as kidneys ) appear one in front of the other instead of side by side , and most have only one functional lung . Some ___MASK88___ retain a pelvic girdle with a pair of vestigial claws on either side of the cloaca . Microsauria (" small lizards ") is an extinct ___MASK80___ of lepospondyl amphibians from the late Carboniferous and early Permian periods . It is the most diverse and ___MASK88___ - rich group of lepospondyls . Recently , Microsauria has been considered paraphyletic , as several other non - microsaur lepospondyl groups such as Lysorophia seem to be nested in it . Microsauria is now commonly used as a collective term for the grade of lepospondyls that were originally classified as members of Microsauria . The microsaurs all had short tails and small legs , but were otherwise quite varied in form . The group included lizard - like animals that were relatively well - adapted to living on dry land , burrowing forms , and others that , like the modern axolotl , retained their gills into adult life , and so presumably never left the water . Amphibians are ectothermic , tetrapod vertebrates of the ___MASK7___ Amphibia . Modern amphibians are all Lissamphibia . They inhabit a wide ___MASK6___ of habitats , with most species living within terrestrial , fossorial , arboreal or freshwater aquatic ecosystems . Thus amphibians typically start out as larvae living in water , but some species have developed behavioural adaptations to bypass this . The young generally undergo metamorphosis from larva with gills to an adult air - breathing form with lungs . Amphibians use their skin as a secondary respiratory surface and some small terrestrial salamanders and frogs lack lungs and rely entirely on their skin . They are superficially similar to lizards but , along with mammals and birds , reptiles are amniotes and do not require water bodies in which to breed . With their complex reproductive needs and permeable skins , amphibians are often ecological indicators ; in recent decades there has been a dramatic decline in amphibian populations for many species around the globe . The Ordovician is a geologic period and system , the second of six periods of the Paleozoic Era . The Ordovician spans 41 . 2 million years from the end of the Cambrian Period million years ago ( Mya ) to the start of the Silurian Period Mya . The Ordovician , named after the Celtic ___MASK54___ of the Ordovices , was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison , who were placing the same rock beds in northern Wales into the Cambrian and Silurian periods , respectively . Lapworth , recognized that the fossil fauna in the disputed strata were different from those of either the Cambrian or the Silurian periods , and placed them in a period of their own . It received international sanction in 1960 , when it was adopted as an official period of the Paleozoic Era by the International Geological Congress . The Cambrian Period ( or ) was the first geological period of the Paleozoic Era , of the Phanerozoic Eon . The Cambrian lasted 55 . 6 million years from the end of the preceding Ediacaran Period 541 million years ago ( mya ) to the beginning of the Ordovician Period mya . Its subdivisions , and its base , are somewhat in flux . The period was established ( as  Cambrian ___MASK21___ ) by Adam Sedgwick , who named it after Cambria , the Latinised form of " Cymru ", the Welsh name for Wales , where Britain ' s Cambrian rocks are best exposed . The Cambrian is unique in its unusually high proportion of lagerstätte sedimentary deposits , sites of exceptional preservation where " soft " parts of organisms are preserved as well as their more resistant shells . As a result , our understanding of the Cambrian biology surpasses that of some later periods . Eurasia is the combined continental landmass of Europe and Asia . The term is a portmanteau of its constituent continents . Located primarily in the Northern and Eastern Hemispheres , it is bordered by the Atlantic Ocean to the west , the Pacific Ocean to the east , the Arctic Ocean to the north , and by Africa , the Mediterranean Sea , and the Indian Ocean to the south . The ___MASK67___ between Europe and Asia as two different continents is a historical and cultural construct , with no clear physical separation between them ; thus , in some parts of the world , Eurasia is recognized as the largest of five or six continents . In geology , Eurasia is often considered as a single rigid megablock . However , the rigidity of Eurasia is debated based on the paleomagnet data . A newt is a salamander in the ___MASK45___ Pleurodelinae , also called eft during its terrestrial juvenile phase . Unlike other members of the ___MASK82___ Salamandridae , newts are semiaquatic , alternating between aquatic and terrestrial habitats over the year , sometimes even staying in the water full - time . Not all aquatic salamanders are considered newts , however . The more than 100 known species of newts are found in North America , Europe , North Africa and Asia . Newts metamorphose through three distinct developmental life stages : aquatic larva , terrestrial juvenile ( eft ), and adult . Adult newts have lizard - like bodies and return to the water every year to breed , otherwise living in humid , cover - rich land habitats . A chordate is any animal belonging to the ___MASK87___ Chordata , possessing a notochord , a hollow dorsal nerve cord , pharyngeal slits , an endostyle , and a post - anal tail for at least some period of its life cycle . The Chordata , together with sister clade Ambulacraria , form the deuterostomes as in the embryo development stage the anus forms before the mouth . Art is a diverse range of human activities in creating visual , auditory or performing artifacts ( artworks ), expressing the author ' s imaginative or technical skill , intended to be appreciated for their beauty or emotional power . In their most general ___MASK69___ these activities include the production of works of art , the criticism of art , the study of the history of art , and the aesthetic dissemination of art . The Paleozoic ( or Palaeozoic ) Era ( from the Greek " palaios " (  ), " old " and " zoe " (  ), " life ", meaning " ancient life ") is the earliest of three geologic eras of the Phanerozoic , from . It is the longest of the Phanerozoic eras , and is subdivided into six geologic periods ( from oldest to youngest ): the Cambrian , Ordovician , Silurian , Devonian , Carboniferous , and Permian . The Paleozoic comes after the Neoproterozoic era of the Proterozoic and is followed by the Mesozoic . Nectridea is the name of an extinct ___MASK80___ of lepospondyl tetrapods from the Carboniferous and Permian periods , including animals such as " Diplocaulus ". In appearance , they would have resembled modern newts or aquatic salamanders , although they are not amphibians . They had long , flattened tails to aid in swimming , and well - developed hind limbs , with a full set of five toes each . Their forelimbs were somewhat reduced , however , and like modern amphibians , typically had only four toes each . Lepospondyli is a diverse ___MASK98___ of Paleozoic tetrapods ( four - limbed vertebrates ) . With the exception of one late - surviving lepospondyl from the Late Permian of Morocco ( Diplocaulus minumus ) , the ___MASK98___ lived from the Early Carboniferous ( Mississippian ) to the Early Permian and was geographically restricted to what is now Europe and North America . Five major groups of lepospondyls are known : Adelospondyli ; Aïstopoda ; Lysorophia ; Microsauria ; and Nectridea . Lepospondyls have a diverse range of body forms and include ___MASK88___ with newt - like , eel - or snake - like , and lizard - like forms . Various ___MASK88___ were aquatic , semiaquatic , or terrestrial . None were large ( the biggest genus , the diplocaulid Diplocaulus , reached a meter in length , but most were much smaller ) , and they are assumed to have lived in specialized ecological niches not taken by the more numerous temnospondyl amphibians that coexisted with them in the Paleozoic . Lepospondyli was named in 1888 by Karl Alfred von Zittel , who coined the name to include some tetrapods from the Paleozoic , that shared some specific characteristics in the notochord and teeth . Europe is a continent that comprises the westernmost part of Eurasia . Europe is bordered by the Arctic Ocean to the north , the Atlantic Ocean to the west , and the Mediterranean Sea to the south . To the east and southeast , Europe is generally considered as separated from Asia by the watershed divides of the Ural and Caucasus Mountains , the Ural River , the Caspian and Black Seas , and the waterways of the Turkish Straits . Yet the non - oceanic borders of Europe  a concept dating back to classical antiquity  are arbitrary . The primarily physiographic term " continent " as applied to Europe also incorporates cultural and political elements whose discontinuities are not always reflected by the continent ' s current overland boundaries . Acherontiscus is an extinct ___MASK49___ of lepospondyl amphibian that lived during the Carboniferous . The type and only ___MASK88___ is " Acherontiscus caledoniae ", named by paleontologist Robert Carroll in 1969 . The ___MASK61___ Tetrapoda ( Ancient Greek s tetrapods , " four - footed "), or the tetrapods , comprises the first four - limbed vertebrates and their descendants , including the living and extinct amphibians , birds , mammals , reptiles and some ancient , exclusively aquatic creatures such as the Acanthostega . Tetrapods evolved from the lobe - finned fishes around 390 million years ago in the middle Devonian Period , with modern tetrapod groups having appeared by the late Devonian , 367 . 5 million years ago . The specific aquatic ancestors of the tetrapods , and the process by which land colonization occurred , remain unclear , and are areas of active research and debate among palaeontologists at present . Lysorophia is an ___MASK80___ of aquatic Carboniferous and Permian amphibians within the extinct ___MASK79___ Lepospondyli . Lysorophians resembled small snakes , as their bodies are extremely elongate . There is a single family , the Cocytinidae ( previously known as Lysorophidae ). Currently there are around five genera included within Lysorophia .