Chondrichthyes is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or bony fish, which have skeletons primarily composed of bone tissue. Chondrichthyes are aquatic vertebrates with paired fins, paired nares, placoid scales, conus arteriosus in the heart, and a lack of opercula and swim bladders. Within the infraphylum Gnathostomata, cartilaginous fishes are distinct from all other jawed vertebrates.
Placoderms are vertebrate animals of the class Placodermi, an extinct group of prehistoric fish known from Paleozoic fossils during the Silurian and the Devonian periods. While their endoskeletons are mainly cartilaginous, their head and thorax were covered by articulated armoured plates, and the rest of the body was scaled or naked depending on the species.
Bennettitales is an extinct order of seed plants that first appeared in the Permian period and became extinct in most areas toward the end of the Cretaceous. Bennettitales were amongst the most common seed plants of the Mesozoic, and had morphologies including shrub and cycad-like forms. The foliage of bennettitaleans is superficially nearly indistinguishable from that of cycads, but they are distinguished from cycads by their more complex flower-like reproductive organs, at least some of which were likely pollinated by insects.
Otodus is an extinct, cosmopolitan genus of mackerel shark which lived from the Paleocene to the Pliocene epoch. The name Otodus comes from Ancient Greek ὠτ- and ὀδούς – thus, "ear-shaped tooth".
The Saint Helena hoopoe, also known as the Saint Helena giant hoopoe or giant hoopoe, is an extinct species of hoopoe known exclusively from an incomplete subfossil skeleton. Once endemic to the island of Saint Helena, it was last seen around 1550, likely driven to extinction by various aspects of human activity.
Epihippus is an extinct genus of the modern horse family Equidae that lived in the Eocene, from 46 to 38 million years ago.
Mixopterus is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of Mixopterus have been discovered in deposits from Late Silurian age, and have been referred to several different species. Fossils have been recovered from two continents; Europe and North America.
Ganorhynchus is an extinct genus of prehistoric lungfish from the Devonian period. Fossils were found in Mansfield, Pennsylvania.
Incisoscutum is an extinct genus of arthrodire placoderm from the Early Frasnian Gogo Reef, from Late Devonian Australia. The genus contains two species I. ritchiei, named after Alex Ritchie, a palaeoichthyologist and senior fellow of the Australian Museum, and I. sarahae, named after Sarah Long, daughter of its discoverer and describer, John A. Long.
Histiostoma is a genus of mites in the family Histiostomatidae.
Microbrachius is an extinct genus of tiny, advanced antiarch placoderms closely related to the bothriolepids. Specimens range in age from the Lower Devonian Late Emsian Stage to the Middle Devonian Upper Givetian Stage. They are characterized by having large heads with short thoracic armor of an average length of 2–4 cm. There are patterns of small, but noticeable tubercles on the armor, with the arrangement varying from species to species. Specimens of Microbrachius have been found in Scotland, Belarus, Estonia, and China.
Venustodus is an extinct genus of cartilaginous fish from the Carboniferous of Russia and the United States. It has been assigned either to the family Cochliodontidae or an indeterminate position within the subclass Holocephali, although in 1984 researcher Rainer Zangerl insisted that nothing is known of the genus' classification and that it may be unrelated to holocephalans. All species of Venustodus are believed to have been nektonic, marine carnivores.
Galeocerdo alabamensis is an extinct relative of the modern tiger shark. Nomenclature of this shark has been debated, and recent literature identified it more closely with the Physogaleus genus of prehistoric shark, rather than Galeocerdo. The classification of Physogaleus is known as tiger-like sharks while Galeocerdo refers to tiger sharks. In 2003, P. alabamensis was classified as Galeocerdo. However, in 2019, they were proclaimed to be more morphologically similar to the genus Physogaleus. This definition was based primarily on tooth shape, as the majority of information on P. alabamensis is a result of studying tooth fossils. Distinctions between Physogaleus and Galeocerdo are difficult with extinct sharks from the Oilgocene/Miocene as there is little paleobiological information allowing for hard conclusions.
The borate carbonates are mixed anion compounds containing both borate and carbonate ions. Compared to mixed anion compounds containing halides, these are quite rare. They are hard to make, requiring higher temperatures, which are likely to decompose carbonate to carbon dioxide. The reason for the difficulty of formation is that when entering a crystal lattice, the anions have to be correctly located, and correctly oriented. They are also known as carbonatoborates or borocarbonates. Although these compounds have been termed carboborate, that word also refers to the C=B=C5− anion, or CB11H12− anion. This last anion should be called 1-carba-closo-dodecaborate or monocarba-closo-dodecaborate.
Sanmiguelia is an extinct plant genus, probably of flowering plants. The genus and the species Sanmiguelia lewisii were first described in 1956 from the Late Triassic Chinle Formation in Colorado, and later in Lower Jurassic Moenave Formation in Utah. The species has been suggested to be one of the more primitive angiosperm fossils.
Tragoportax is an extinct genus of bovid ungulate. It lived during the upper Miocene, and its fossils have been found in Europe, Asia and Africa. Tragoportax is sometimes considered to have been a close relative of the extant nilgai, though it may have formed its own subfamily, along with Miotragocerus.
Protea amplexicaulis, the clasping-leaf sugarbush, is a flower-bearing shrub that belongs to the genus Protea. The plant is endemic to the Cape Provinces of South Africa and occurs from Citrusdal to the Kogelberg, as well as in the Langeberg. The shrub remains low and spreads out, becoming 1.3 m in diameter and flowering from June to September.
Pelourdea is an extinct genus of conifer. Species belonging to the genus lived from the Triassic to the Middle Jurassic and have been found in Europe and North America.
Romerodus is an extinct genus of cartilaginous fish in the family Caseodontidae. While it and the rest of its family were historically considered elasmobranchs related to sharks and rays, they are now regarded as holocephalans, a diverse subclass which is today only represented by chimaeras. Romerodus is known from the Carboniferous and possibly Permian periods of North America, and the only named species, R. orodontus, was discovered in organic shale deposits in the U.S. state of Nebraska. It is one of few members of its order, the Eugeneodontida, that is known from multiple complete, well preserved body fossils, and is thus an important taxon for understanding the anatomy and ecology of less well preserved eugeneodonts such as Helicoprion. Unlike its larger relatives, the largest known Romerodus were approximately 50 cm (20 in) in total length.
Rhea fossilis is an extinct species of bird in the genus Rhea that inhabited the Southern Cone of South America during the Neogene period. Its closest living relatives are the greater rhea and the lesser rhea.
