Journal of the Arkansas Academy of Science Volume 9 Article 6 1956 Scheme of General Classification in the Phylum Chordata Paul R. Harding Hendrix College Follow this and additional works at: http://scholarworks.uark.edu/jaas Part of the Zoology Commons Recommended Citation Harding, Paul R. (1956) "Scheme of General Classification in the Phylum Chordata," Journal of the Arkansas Academy of Science: Vol. 9 , Article 6. Available at: http://scholarworks.uark.edu/jaas/vol9/iss1/6 This article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able to read, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking prior permission from the publisher or the author. This Article is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the Arkansas Academy of Science by an authorized editor of ScholarWorks@UARK. For more information, please contact [email protected], [email protected]. Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 6 A SCHEME OF GENERAL CLASSIFICATION IN THE PHYLUM CHORDATA Paul R. Harding, Jr. Hendrix College Phylum, Chordata Subphylum, Hemichordata Balanoglossus, Sacco- glossus (Dolichoglossus ) Subphylura, Protochordata Class, Cephalochordata Branchiostoma (Am- phioxus) Class, Urochordata (Tunicata) Order, Ascidiacea sea squirts Order, Thaliacea salpians Order, Larvacea larvacians Subphylum, Vertebrata (Craniata) Branch, Agnatha (Monorhina) with single nos- tril and circular mouth without jaws Class, Ostracodermi armored fishes ; ex- tinct Orders: Osteostraci, Heterostraci, An- aspida Class, Cyclostomata Unarraored, eel-like Order, Myxinoidea hagfishes Order, Petromyzontia lampreys Branch, Gnathostomata (Amphirhina) two nos- trils and with jaws Grade, Pisces fishlike gnathostomes Class, Placodermi (Aphetohyoidea) ar- mored fishes; extinct Orders: Arthrodira, Acanthodii, An- tiarchi , Petalichthyida, Rhenanida, Palaeospondylia Class, Chondrichthyes ( Elasmobranchii) Cartilaginous fishes with gill septa (separate gill clefts) Published by Arkansas Academy of Science, 1956 20 20 Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 6 THE PHYLUM CHORDATA Order, Cladoselachii Cladoselache; extinct Order, Pleuracanthodii Pleuracan- thus, extinct Order, Selachii Suborder, Squali sharks Suborder, Raji (Batoidea) skates, rays, sawfish, guitar fish Order, Bradyodonti Ancestral to Ho- locephali. Extinct. Coch- liodus; Psammodus Order, Holocephali chimeras Class, Osteichthyes bony fishes with- out separate gill clefts Subclass, Choanichthyes primitive bony fishes; nostrils con- nected to mouth cavity Order, Crossopterygii lobe-finned fishes; ancestral to Tetra- poda Suborder, Actinistia Family, Coelacanthidae Latimeria chalumnae (193B, 1952, 1953, 1954) Suborder, Rhipidistia Families: Osteolepidae, Rhi- zodontidae, Urostheneidae, Holoptychiidae, Tarrasi- idae Order, Dipnoi (Dipneusti) Lung- fishes proper Subclass, Actinopterygii (Teleostomi) ray-finned fishes; nos- trils not connected to mouth cavity Superorders: Chondrostei, Holo- stei, Teleostei Grade, Tetrapoda http://scholarworks.uark.edu/jaas/vol9/iss1/6 21 21 I Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 6 ARKANSAS ACADEMY OF SCIENCE Subgrade, Anamniota without extraem- bryonic membranes Class, Amphibia Subclass, Stegocephalia skull and cheeks roofed with bony plates Order, Labyrinthodontia teeth with abundantly infolded dentine in the pulp cavityj body armored with scales or plates; extinct Order, Gymnophiona (Apoda)-- Caecilians Subclass, Caudata (Urodela) sal- amanders and newts Subclass, Salientia (Anura) frogs and toads Subgrade, Araniota with extraembryonic membranes Class, Reptilia Order, Squamata Suborder, Lacertilia (Sauria) lizards Suborder, Ophidia (Serpentes) snakes Order, Rhynchocephalia Spheno- don, unampsosaurusChamps osaurus Order, Testudinatainata (Chelonia)--(Chelon tortoises, terrapins, tur- tles Order, Crocodilia (Loricata) — crocodiles, alligators, gavials, caimans Order, Cotylosauria Primitive extinct reptiles, closely resembling the most primi- tive amphibians (Labyrin- thodontia) and of great phylogenetic importance as Published by Arkansas Academy of Science, 1956 22 22 Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 6 THE PHYLUM CHORDATA links with them. Example: Seymouria . Order, Mosasauria Extinct large aquatic reptiles with long snake-like scaly bodies, a crocodile-like head, strong recurved teeth, and two pairs of flippers in place of legs. Examples: Mosa- saurus , Clidastes, Tylo- saurus, etc. Order, Ichthyosauria —Extinct fish- like reptiles with long tapering rostrum. Exam- ples : Ichthyosaurus, Sten- opterygius . Order, Plesiosauria Extinct long- necked aquatic reptiles with flippers in place of legs. Example: ELasmosau- rus. Order, Pterosauria Extinct flying reptiles, pterodactyls . Examples: Pteranodon,Hham- phorhynchus. Order, Thecodontia (Phytosauria) Extinct crocodile-like reptiles with long narrow jaws, and nostrils close in front of the eyes rather than on the end of the snout. Examples: Belodon , Hystriosuchus . Order, Pelycosauria Fin -back lizards; extinct. Exam- pies: Dimetrodon, Eda- phosaurus. Ophiacodonti- dae (example: Ophiacodon) ancestral to mammals. 23 http://scholarworks.uark.edu/jaas/vol9/iss1/6 23 1 Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 6 ARKANSAS ACADEMY OF SCIENCE Order, Dinosauria Extinct gen- eralized bird-like and li- zard-like forms; contains ttie largest, most grotesque and most variable reptiles. Suborder, Ornithischia With bird -like pelvis; bird- beaked, duck-billed, bird- footed, seme ostrich-like, etc. Examples: Ornithom- imus and Struthiomimus , ostrich- like; Trachodon , duck -bUlsd dinosaur; £qry- thosaurus, hooded duck-bill dinosaur; Stegosaurug, two rows of vertical plates on back, brain exceptionally- small, spinal cord vdth brachial and sacral en- largements ; Trlceratops , head with three horns and the skull extended like a shield over the back and shoulde rs ; Ankylosaurus , armored . Suborder, -Saurischia VJ±fcli li- zard like pelvis. Exam- ples : Tyrannosaurus, Brcn- tosaurus, Brachiosaurus , Diplodocus, Comosognathus . Order, Therapsida Extinct mammal- like reptiles. Example: Cynognathus . Evolved fro:n order Pelycosauria, but not ancestral to mammals. Class, Aves birds Subclass, Archaeornithes "Ancient birds" showing reptilian ancestry; extinct. Exam- Published by Arkansas Academy of Science, 1956 24 24 Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 6 THE PHYLUM CHORDATA pies: Archaeornis , Ar- chaeopteryx. Subclass, Neornithes "New birds" Superorder, Odontormae Ich- thyornis; extinct. Toothed; good flyer. Superorder, Odontolcae Hes- perornis; extinct. Also with true teeth in sockets; a flightless (wingof hum- erus only) diver. Superorder, Ratitae Cursorial flightless birds with un- keeled sternum. Examples: ostrich, rhea, emu, casso- wary, kiwi, elephant bird, moa. Superorder, Carinatae Adapted for flight, sternum keeled. Great majority of modern birds. Class, Mammalia Subclass, Prototheria egg-laying mammals . Order, Monotremata duckbill and spiny anteater. Order, Multituberculata an extinct group of doubtful position. Subclass, Theria viviparous mam- mals. Infraclass, Metatheria (Didel- phia) —viviparous mammals usually without allantoic placenta. Order, Marsupialia pouched mammals. Opossum, kanga- roo, wombat, wallaby, fly- ing phalange r, koala, mar- http://scholarworks.uark.edu/jaas/vol9/iss1/6 25 25 ¦ Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 6 ARKANSAS ACADEMY OF SCIENCE supial mole, bandicoot, marsupial mouse, Tasmanian wolf, Tasmanian devil, ti- ger cat, etc. Extinct orders of doubtful position: ffcntotheria (also called Trituberculata probably ancestral to la- ter types of mammals). Triconodonta, Symmetrodon- ta. Infraclass, Eutheria (Monodel- fhia) viviparous mammals with allantoic placenta. Superorder, Unguiculata clawed mammals . Sloths, pangolin or scaly anteater, hairy anteater, rabbi ts , armadillos, aardvark, ro- dents, bats, carnivores, insect ivores, sealions, seals, walruses, etc. Superorder, Primates mam- mals with nails Order, Lemuroidea le- murs . Ruff e d lemur, mouse lemur, tiee shrews, slowloris, aye-aye (Chi- romys ), etc. Order, Tarsioidea tar- siers Order, Anthropoidea an- thropoids. Men, apes, monkeys . Superorder, Ungulata —hoofed mammals. Order, Condylarthra — condylarths; extinct Published by Arkansas Academy of Science, 1956 26 26 Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 6 THE PHYLUM CHORDATA Order, Dinocerata Uin- tatheres; extinct Order, Sirenia dugongs and manatees. Large fishlike forms believed to have an ungulate or- igin. Order, Peris sodactyla foot withan odd number of toes, each usually sheathed in a cornified hoof. Asses, zebras, horses, tapirs, rhinoc- eroses, titanotheres, chalicotheros . Order, Artiodactyla foot with even number of toes, each usually- sheathed ina cornified hoof. Pigs, hippopot- amuses, and such rumi- nants as camels, chev- rotians (mouse deer), deer, elk, moose, an- telope, giraffes, cat- tle, bison, ox, water buffalo, cape buffalo, sheep, goats, musk ox, llama, etc. Order, Proboscidea —num- ber of toes odd or even, each with small nail- like hoof, nose and up- per lip combined into along muscular probos- cis. Elephants, masto- dons, mammoths. Order, Hyracoidea