Trilobites are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period and they flourished throughout the lower Paleozoic before slipping into a long decline, when, during the Devonian, all trilobite orders except the Proetida died out. The last extant trilobites finally disappeared in the mass extinction at the end of the Permian about 251.9 million years ago. Trilobites were among the most successful of all early animals, existing in oceans for almost 270 million years, with over 22,000 species having been described.
Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids than they are to shelled nautiloids such as the living Nautilus species. The earliest ammonites appeared during the Devonian, with the last species vanishing during or soon after the Cretaceous–Paleogene extinction event.
The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, these two parts are the neurocranium and the viscerocranium that includes the mandible as its largest bone. The skull forms the anterior-most portion of the skeleton and is a product of cephalisation—housing the brain, and several sensory structures such as the eyes, ears, nose, and mouth. In humans these sensory structures are part of the facial skeleton.
The occipital bone is a cranial dermal bone and the main bone of the occiput. It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone overlies the occipital lobes of the cerebrum. At the base of the skull in the occipital bone, there is a large oval opening called the foramen magnum, which allows the passage of the spinal cord.
Forceps are a handheld, hinged instrument used for grasping and holding objects. Forceps are used when fingers are too large to grasp small objects or when many objects need to be held at one time while the hands are used to perform a task. The term "forceps" is used almost exclusively in the fields of biology and medicine. Outside biology and medicine, people usually refer to forceps as tweezers, tongs, pliers, clips or clamps.
Goniatids, informally goniatites, are ammonoid cephalopods that form the order Goniatitida, derived from the more primitive Agoniatitida during the Middle Devonian some 390 million years ago. Goniatites (goniatitids) survived the Late Devonian extinction to flourish during the Carboniferous and Permian only to become extinct at the end of the Permian some 139 million years later.
Cauliflower ear is an irreversible condition that occurs when the external portion of the ear is hit and develops a blood clot or other collection of fluid under the perichondrium. This separates the cartilage from the overlying perichondrium that supplies its nutrients, causing it to die and resulting in the formation of fibrous tissue in the overlying skin. As a result, the outer ear becomes permanently swollen and deformed, resembling a cauliflower.
The frontal suture is a fibrous joint that divides the two halves of the frontal bone of the skull in infants and children. Typically, it completely fuses between three and nine months of age, with the two halves of the frontal bone being fused together. It is also called the metopic suture, although this term may also refer specifically to a persistent frontal suture.
The petrosquamous suture is a cranial suture between the petrous portion and the squama of the temporal bone. It forms the Koerner's septum. The petrous portion forms the medial component of the osseous margin, while the squama forms the lateral component. The anterolateral portion (squama) arises from the mesenchyme at 8 weeks of embryogenesis while the petromastoid portion develops later from a cartilaginous center at 6 months of fetal development.
The Andrenidae are a large, nearly cosmopolitan family of solitary, ground-nesting bees. Most of the family's diversity is located in temperate or arid areas. It includes some enormous genera. One of the subfamilies, Oxaeinae, is so different in appearance that they were typically accorded family status, but careful phylogenetic analysis reveals them to be an offshoot within the Andrenidae, very close to the Andreninae.
Tornoceratina is one of two suborders included in the Goniatitida, characterized by generally involute, subdiscoidal shells and by sutures in which the ventral ones are undivided.
The lambda is the meeting point of the sagittal suture and the lambdoid suture. This is also the point of the occipital angle. It is named after the Greek letter lambda.
Phantomosaurus is an extinct genus of ichthyosaur that lived during the late Anisian stage of the Middle Triassic. Fossils have been found in southern Germany. It was discovered in 1965 and named in 1997 as a species of Shastasaurus by Sander in the rocks of the Upper Muschelkalk.
The Naedyceras group comprises three similar and closely related openly coiled, gyroconic, genera within oncocerid family, Brevicoceratidae: Naedyceras, Gonionaedyceras, and Gyronaedyceras.
Siberionautilidae is a family in the nautilid superfamily Clydonautiloidea that contains only the genus Siberionautilus, which comes from the Upper Triassic (Carnian) of Siberia, Russia.
Surgical scissors are scissors specially manufactured as surgical instruments, typically used for cutting sutures, dressings, and cutting and dissecting biological tissue. Surgical scissors are usually made of surgical steel. Some have tungsten carbide reinforcements along their cutting edges, the hardness of which allows manufacturers to create sharper and more durable edges.
The cephalon is the head section of an arthropod. It is a tagma, i.e., a specialized grouping of arthropod segments. The word cephalon derives from the Greek κεφαλή (kephalē), meaning "head".
Lytoceratidae is a taxonomic family of ammonoid cephalopods belonging to the suborder Lytoceratina, characterized by very evolute shells that generally enlarge rapidly, having whorls in contact but mostly overlapping very sightly, or not at all.
Ophiceras is a genus of smooth, evolute ceratitid ammonites from the Early Triassic, with a rounded venter. Fossils of the genus have been found in Armenia, Azerbaijan, China, Greenland, and India.
Lepidus is a genus of extinct theropod from the Upper Triassic of the United States. It lived in the Otis Chalk localities of the Dockum Group in Texas, around 223 million years ago.
