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Psephoderma
''Psephoderma'' (meaning "pebbly skin", from the Ancient Greek ''psepho'' (ψῆφος), "pebbly", and ''derma'' (δέρμα), "skin") is a genus of placodonts very similar to the related genera ''Placochelys'' and ''Cyamodus''. ''Psephoderma'' had a flattened skull and a narrow, straight rostrum, much narrower than that of its relatives. Inside this skull, embedded in the jaws, were rounded teeth specialized for crushing the shellfish it ate. Unlike henodontid placodonts, ''Psephoderma'''s carapace was divided into two pieces, one on the shoulders and back, and another on the ventral end. ''Psephoderma'' grew to long, larger than many of its relatives, and lived in the Late Triassic ( Norian - Rhaetian), about 210 million years ago. It was one of the last placodonts to live. Fossils of ''Psephoderma'' have been found in the Rhaetian deposits in the Alps and in England, hence the specific names. Description ''Psephoderma'' had a long, narrow rostrum, which was the main differ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Psephoderma New NT
''Psephoderma'' (meaning "pebbly skin", from the Ancient Greek ''psepho'' (ψῆφος), "pebbly", and ''derma'' (δέρμα), "skin") is a genus of placodonts very similar to the related genera ''Placochelys'' and ''Cyamodus''. ''Psephoderma'' had a flattened skull and a narrow, straight rostrum, much narrower than that of its relatives. Inside this skull, embedded in the jaws, were rounded teeth specialized for crushing the shellfish it ate. Unlike henodontid placodonts, ''Psephoderma'''s carapace was divided into two pieces, one on the shoulders and back, and another on the ventral end. ''Psephoderma'' grew to long, larger than many of its relatives, and lived in the Late Triassic ( Norian - Rhaetian), about 210 million years ago. It was one of the last placodonts to live. Fossils of ''Psephoderma'' have been found in the Rhaetian deposits in the Alps and in England, hence the specific names. Description ''Psephoderma'' had a long, narrow rostrum, which was the main differ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Placodont
Placodonts (" Tablet teeth") are an extinct order of marine reptiles that lived during the Triassic period, becoming extinct at the end of the period. They were part of Sauropterygia, the group that includes plesiosaurs. Placodonts were generally between in length, with some of the largest measuring long. The first specimen was discovered in 1830. They have been found throughout central Europe, North Africa, the Middle East and China. Palaeobiology The earliest forms, like ''Placodus'', which lived in the early to middle Triassic, resembled barrel-bodied lizards superficially similar to the marine iguana of today, but larger. In contrast to the marine iguana, which feeds on algae, the placodonts ate molluscs and so their teeth were flat and tough to crush shells. In the earliest periods, their size was probably enough to keep away the top sea predators of the time: the sharks. However, as time passed, other kinds of carnivorous reptiles began to colonize the seas, such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyamodus
''Cyamodus'' (pron.: SIE-ah-MO-dus) is a genus of placodonts known from several species described from Middle-Late Triassic of Europe and China. The genus was described by Christian Erich Hermann von Meyer in 1863, based on specimens found in Germany. Like some other placodonts, ''Cyamodus'' has an armoured carapace composed of irregular hexagonal plates, with the mouth containing a small number of large, rounded teeth that were likely involved in crushing hard shelled organisms (durophagy). Discovery Thus far, six species of ''Cyamodus'' have been identified - ''C. rostratus'', ''C. munsteri'', ''C. tarnowitzensis'', ''C. hildegardis'', ''C. kuhnschneyderi'', and ''C. orientalis''. Initially considered to be an ancestral turtle due to its testudine-like head and large, bifurcated carapace. However further investigation resulted in its reclassification as a placodont, and it is closely related to other turtle-like reptiles of the Triassic period such as ''Henodus'' and ''Psephod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Triassic
The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch and followed by the Early Jurassic Epoch. The corresponding series (stratigraphy), series of rock beds is known as the Upper Triassic. The Late Triassic is divided into the Carnian, Norian and Rhaetian Geologic time scale, Ages. Many of the first dinosaurs evolved during the Late Triassic, including ''Plateosaurus'', ''Coelophysis'', and ''Eoraptor''. The Triassic–Jurassic extinction event began during this epoch and is one of the five major mass extinction events of the Earth. Etymology The Triassic was named in 1834 by Friedrich August von Namoh, Friedrich von Alberti, after a succession of three distinct rock layers (Greek meaning 'triad') that are widespread in southern Germany: the lower Buntsandstein (colourful sandstone'')'', t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protenodontosaurus
''Protenodontosaurus'' is an extinct genus of placodont Placodonts (" Tablet teeth") are an extinct order of marine reptiles that lived during the Triassic period, becoming extinct at the end of the period. They were part of Sauropterygia, the group that includes plesiosaurs. Placodonts were genera ... from Italy. References {{Taxonbar, from=Q5559564 Placodonts Prehistoric reptile genera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nasal Bone
The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face and by their junction, form the bridge of the upper one third of the nose. Each has two surfaces and four borders. Structure The two nasal bones are joined at the midline internasal suture and make up the bridge of the nose. Surfaces The ''outer surface'' is concavo-convex from above downward, convex from side to side; it is covered by the procerus and nasalis muscles, and perforated about its center by a foramen, for the transmission of a small vein. The ''inner surface'' is concave from side to side, and is traversed from above downward, by a groove for the passage of a branch of the nasociliary nerve. Articulations The nasal articulates with four bones: two of the cranium, the frontal and ethmoid, and two of the face, the opposite nasal and the maxilla. Other animals In primitive bony fish and tetrapod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbit (anatomy)
In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents. In the adult human, the volume of the orbit is , of which the eye occupies . The orbital contents comprise the eye, the orbital and retrobulbar fascia, extraocular muscles, cranial nerves II, III, IV, V, and VI, blood vessels, fat, the lacrimal gland with its sac and duct, the eyelids, medial and lateral palpebral ligaments, cheek ligaments, the suspensory ligament, septum, ciliary ganglion and short ciliary nerves. Structure The orbits are conical or four-sided pyramidal cavities, which open into the midline of the face and point back into the head. Each consists of a base, an apex and four walls."eye, human."Encyclopædia Britannica from Encyclopædia Britannica 2006 Ultimate Reference Suite DVD 2009 Openings There are two important foramina, or windows, two important fissu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pineal Foramen
A parietal eye, also known as a third eye or pineal eye, is a part of the epithalamus present in some vertebrates. The eye is located at the top of the head, is photoreceptive and is associated with the pineal gland, regulating circadian rhythmicity and hormone production for thermoregulation. The hole in the head which contains the eye is known as a pineal foramen or parietal foramen, since it is often enclosed by the parietal bones. Presence in various animals The parietal eye is found in the tuatara, most lizards, frogs, salamanders, certain bony fish, sharks, and lampreys. It is absent in mammals, but was present in their closest extinct relatives, the therapsids, suggesting it was lost during the course of the mammalian evolution due to it being useless in endothermic animals. It is also absent in the ancestrally endothermic ("warm-blooded") archosaurs such as birds. The parietal eye is also lost in ectothermic ("cold-blooded") archosaurs like crocodilians, and in turtles, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frontal Bone
The frontal bone is a bone in the human skull. The bone consists of two portions.''Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, part of the bony orbital cavity holding the eye, and part of the bony part of the nose respectively. The name comes from the Latin word ''frons'' (meaning " forehead"). Structure of the frontal bone The frontal bone is made up of two main parts. These are the squamous part, and the orbital part. The squamous part marks the vertical, flat, and also the biggest part, and the main region of the forehead. The orbital part is the horizontal and second biggest region of the frontal bone. It enters into the formation of the roofs of the orbital and nasal cavities. Sometimes a third part is included as the nasal part of the frontal bone, and sometimes this is included with the squamous part. The nasal part is between the brow ridges, and ends in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palate
The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly separated. The palate is divided into two parts, the anterior, bony hard palate and the posterior, fleshy soft palate (or velum). Structure Innervation The maxillary nerve branch of the trigeminal nerve supplies sensory innervation to the palate. Development The hard palate forms before birth. Variation If the fusion is incomplete, a cleft palate results. Function When functioning in conjunction with other parts of the mouth, the palate produces certain sounds, particularly velar, palatal, palatalized, postalveolar, alveolopalatal, and uvular consonants. History Etymology The English synonyms palate and palatum, and also the related adjective palatine (as in palatine bone), are all from the Latin ''palatum'' via Old French ''palat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tooth
A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tearing food, for defensive purposes, to intimidate other animals often including their own, or to carry prey or their young. The roots of teeth are covered by gums. Teeth are not made of bone, but rather of multiple tissues of varying density and hardness that originate from the embryonic germ layer, the ectoderm. The general structure of teeth is similar across the vertebrates, although there is considerable variation in their form and position. The teeth of mammals have deep roots, and this pattern is also found in some fish, and in crocodilians. In most teleost fish, however, the teeth are attached to the outer surface of the bone, while in lizards they are attached to the inner surface of the jaw by one side. In cartilaginous fish, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Premaxilla
The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has been usually termed as the incisive bone. Other terms used for this structure include premaxillary bone or ''os premaxillare'', intermaxillary bone or ''os intermaxillare'', and Goethe's bone. Human anatomy In human anatomy, the premaxilla is referred to as the incisive bone (') and is the part of the maxilla which bears the incisor teeth, and encompasses the anterior nasal spine and alar region. In the nasal cavity, the premaxillary element projects higher than the maxillary element behind. The palatal portion of the premaxilla is a bony plate with a generally transverse orientation. The incisive foramen is bound anteriorly and laterally by the premaxilla and posteriorly by the palatine process of the maxilla. It is formed from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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