The relationships of Uronemus : A Carboniferous dipnoan with highly modified tooth plates

1987 ◽  
Vol 317 (1185) ◽  
pp. 299-327 ◽  
Keyword(s):  
Tissue Type ◽  
Close Relative ◽  
Marginal Tooth ◽  
Thin Sections ◽  
Scanning Electron Microscope Study ◽  
Air Breathing ◽  
Dental Tissues ◽  
Lower Jaw ◽  
Tooth Plate ◽  
Evolutionary Phase

Previous accounts of the dentition of the Carboniferous dipnoan Uronemus have stressed the significance of the scattered small denticles. These, together with the marginal teeth and ridges, have been interpreted as primitive characters of the dipnoan dentition shared with three other genera: the Devonian Uranolophus and Griphognathus and the Carboniferous to Permian Conchopoma . Genera with tooth plates have been considered to be a monophyletic group in which tooth plates are a derived character; Uronemus has been excluded from this group in all previous investigations dealing with the significance of the dentition for determining relationships among dipnoans. The macromorphology of the dentition of Uronemus has been re-examined and correlated with the histology of all the dental tissues. Optical study of thin sections and scanning electron microscope study of the adjacent cut surfaces has shown that the hard, wear-resistant dentine of the teeth and ridges is petrodentine. The arrangement, growth, wear and histology of the dental tissues have been compared with those of denticulated and tooth-plated genera. The arrangement of new teeth relative to the tooth ridge, the pattern of wear along the ridge, and the type of dentine and its growth indicate that the dentition of Uronemus is best interpreted as a tooth plate with one long lingual tooth ridge and reduced lateral tooth rows. Therefore the marginal tooth ridges are not considered to be homologous with those of denticulate dipnoans such as Uranolophus . The presence of petrodentine, a tissue type only found in forms with tooth plates, is consistent with the view that the dentition is derived by modification of a radiate tooth plate. The denticles covering restricted regions of the palate and lower jaw are considered to have been a secondary acquisition. The suggestion that Conchopoma is a close relative of Uronemus is not accepted, and possible new relationships have been proposed. New data on Scaumenacia and Phaneropleuron , two other genera previously compared with Uronemus , are presented. Rhinodipterus , a form with elongate lingual ridges, is also discussed. Phaneropleuron is shown to have radiate tooth plates and not a marginal row of conical teeth as previously described. It is proposed that the tooth plate of Uronemus is derived from a dipterid type of plate. A discussion of some of the other factors involved in determining the relationships of the genus is given. From an examination of the use of the tongue for respiration and feeding by the extant Lepidosiren paradoxa , it is concluded that many features of dipnoan evolution in the tooth-plated lineage result from the adoption of air breathing after an early evolutionary phase of gill respiration, and that Uronemus was adapted for air breathing. The ‘denticulated’ lineage, which included genera such as Uranolophus and Griphognathus , shows none of the skeletal features associated with the presence of a tongue, and presumably did not become air breathing.

scholarly journals Incremental growth of therizinosaurian dental tissues: implications for dietary transitions in Theropoda

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e4129 ◽  
Author(s):  
Khai Button ◽  
Hailu You ◽  
James I. Kirkland ◽  
Lindsay Zanno
Keyword(s):  
Morphological Evidence ◽  
Thin Sections ◽  
Dental Tissues ◽  
Theropod Dinosaurs ◽  
Crown Volume ◽  
Dietary Strategy ◽  
Incremental Growth ◽  
Dental Microstructure ◽  
Dinosaur Teeth ◽  
Tooth Growth

Previous investigations document functional and phylogenetic signals in the histology of dinosaur teeth. In particular, incremental lines in dentin have been used to determine tooth growth and replacement rates in several dinosaurian clades. However, to date, few studies have investigated the dental microstructure of theropods in the omnivory/herbivory spectrum. Here we examine dental histology of Therizinosauria, a clade of large-bodied theropods bearing significant morphological evidence for herbivory, by examining the teeth of the early-diverging therizinosaurian Falcarius utahensis, and an isolated tooth referred to Suzhousaurus megatherioides, a highly specialized large-bodied representative. Despite attaining some of the largest body masses among maniraptoran theropod dinosaurs, therizinosaurian teeth are diminutive, measuring no more than 0.90 cm in crown height (CH) and 0.38 cm in crown base length (CBL). Comparisons with other theropods and non-theropodan herbivorous dinosaurs reveals that when controlling for estimated body mass, crown volume in therizinosaurians plots most closely with dinosaurs of similar dietary strategy as opposed to phylogenetic heritage. Analysis of incremental growth lines in dentin, observed in thin sections of therizinosaurian teeth, demonstrates that tooth growth rates fall within the range of other archosaurs, conforming to hypothesized physiological limitations on the production of dental tissues. Despite dietary differences between therizinosaurians and hypercarnivorous theropods, the types of enamel crystallites present and their spatial distribution—i.e., the schmelzmuster of both taxa—is limited to parallel enamel crystallites, the simplest form of enamel and the plesiomorphic condition for Theropoda. This finding supports previous hypotheses that dental microstructure is strongly influenced by phylogeny, yet equally supports suggestions of reduced reliance on oral processing in omnivorous/herbivorous theropods rather than the microstructural specializations to diet exhibited by non-theropodan herbivorous dinosaurs. Finally, although our sample is limited, we document a significant reduction in the rate of enamel apposition contrasted with increased relative enamel thickness between early and later diverging therizinosaurians that coincides with anatomical evidence for increased specializations to herbivory in the clade.

scholarly journals Climatic influence on the growth pattern of Panthasaurus maleriensis from the Late Triassic of India deduced from paleohistology

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9868
Author(s):  
Elżbieta M. Teschner ◽  
Sanjukta Chakravorti ◽  
Dhurjati P. Sengupta ◽  
Dorota Konietzko-Meier
Keyword(s):  
Growth Pattern ◽  
Environmental Influence ◽  
Wide Spectrum ◽  
Climatic Conditions ◽  
Bone Histology ◽  
Late Triassic ◽  
Tissue Type ◽  
Thin Sections ◽  
Local Climate ◽  
Limb Bones

Metoposaurids are representatives of the extinct amphibian clade Temnospondyli, found on almost every continent exclusively in the Late Triassic deposits. Osteohistologically, it is one of the best-known temnospondyl groups, analyzed with a wide spectrum of methods, such as morphology, morphometry, bone histology or computed modelling. The least known member of Metoposauridae is Panthasaurus maleriensis from the Pranhita-Godavari basin in Central India, being geographically the most southern record of this family. For the first time the bone histology of this taxon was studied with a focus on the intraspecific variability of the histological framework and the relationship between the observed growth pattern and climatic and/or environmental conditions. The studied material includes thin-sections of five long bones, a rib, an ilium and an intercentrum belonging most likely to eight individuals ranging from different ontogenetic stages. All bones have a large medullary region with progressively increasing remodeling, surrounded by a lamellar-zonal tissue type. The primary cortex consists of parallel-fibered matrix showing various degrees of organization, less organized collagen fibers in the zones and higher organized in the annuli. Growth marks occur in the form of alternating zones and annuli in every bone except the ilium and the intercentrum. The vascularity becomes less dense towards the outermost cortex in all sampled limb bones. Towards the outermost cortex the zone thickness is decreasing, in contrast to the avascular annuli, that become thicker or are of the same thickness. The growth pattern of P. maleriensis is uniform and represents changes in ontogenetic development. Multiple resting lines are prominent in the outer annuli of the limb bones and the rib and they presumably indicate climatic and environmental influence on the growth pattern. Therefore, a prolonged phase of slowed-down growth occurred during the unfavorable phase, but a complete cessation of growth indicated by Lines of Arrested Growth (LAGs) is not recorded in the studied samples. Based on the histological framework we conclude that the climate had an impact on the growth pattern. As we do not see any LAGs in the Indian metoposaurid, we assume that the local climate was relatively mild in India during the Late Triassic. A similar prolonged phase of slowed down growth without the occurrence of LAGs was observed in Metoposaurus krasiejowensis from the Late Triassic of Krasiejów (Poland). This is in contrast to Moroccan metoposaurid Dutuitosaurus ouazzoui from the Late Triassic of Argana Basin, where LAGs are regularly deposited throughout ontogeny indicating most likely harsher climatic conditions.

Plexiform Unicystic Ameloblastoma - A Diagnostic Dilemma

2021 ◽  
Vol 7 (2) ◽  
Author(s):  
Rai DV ◽  
◽  
Guttal KS ◽  
Burde KN ◽  
Hallikeri K ◽  
...  
Keyword(s):  
Definitive Diagnosis ◽  
Odontogenic Cysts ◽  
Diagnostic Dilemma ◽  
Dental Tissues ◽  
Lower Jaw ◽  
Unicystic Ameloblastoma ◽  
Odontogenic Origin ◽  
Phases Of Development ◽  
Slow Growing ◽  
Posterior Area

The 2nd most common tumor of odontogenic origin is Ameloblastoma which develops from epithelial cellular elements and dental tissues in various phases of development. It is a slow-growing, persistent and locally aggressive neoplasm of epithelial origin, affecting the posterior area of lower jaw in 80% of cases. Unicystic Ameloblastoma (UA) is one of the less encountered variants of Ameloblastoma. Radiographically it mimics many of the odontogenic cysts and tumors and hence becomes difficult to arrive at a definitive diagnosis. We report here a case of plexiform unicystic variant of ameloblastoma in a 26 years old male patient.

The role of carbohydrate-protein biopolymers and hyaluronic acid at the resistance formation of hard dental tissues against pathological processes of carious and non-carious genesis

10.12737/7378 ◽  
2014 ◽  
Vol 8 (1) ◽  
pp. 0-0
Author(s):  
Лещева ◽  
E. Leshcheva ◽  
Ипполитов ◽  
I. Ippolitov ◽  
Ипполитов ◽  
...  
Keyword(s):  
Hyaluronic Acid ◽  
Soft Tissues ◽  
Human Tooth ◽  
Cationic Protein ◽  
Thin Sections ◽  
Tooth Structure ◽  
Dental Tissues ◽  
Protein Nature ◽  
Hard Dental Tissues ◽  
Special Studies

At the series of histochemical studies hypothesis of existence of a "cationic protein" in human tooth structure and set of its amino acids components and hyaluronic acid has been checked. Taking into account histogenesis and cytogeny of tooth structure and the earlier results received from the epidermis and multilayer partly keratinous epithelium of the oral mucosa, special studies had been created, based on the original equipment preparation of paraffin sections, and thin sections of the whole teeth and modified histochemical identification technology of carbohydrate-protein biopolymers in hard dental tissues. Histological slides are prepared from extracted for orthodontic indications teeth. Sectioned and examined thin sections of teeth has investigated in transmitted light for issues related to topochemistry of carbohydrate-protein biopolymers and hyaluronic acid concerning the distribution in structures of enamel, dentin, predentin, cellular and acellular cement. Identified carbohydrate-protein biopolymers and substances of protein nature objectively fill inter prismatic enamel areas, dentin tubules and their walls, localized in the cement structure of tooth and its soft tissues forming a physiologi-cal barrier to microorganisms and their metabolic products as in the demineralizing processes as for the mechan-ical interventions during the vital activity and medical interventions.

scholarly journals A unique mineralization mode of hypermineralized pleromin in the tooth plate of Chimaera phantasma contributes to its microhardness

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Mayumi Iijima ◽  
Mikio Ishiyama
Keyword(s):  
Dietary Habits ◽  
Tooth Enamel ◽  
The Other ◽  
Mineralized Tissue ◽  
Mineral Phase ◽  
Lower Jaw ◽  
Other Hand ◽  
Tooth Plate ◽  
Dental Hard Tissues ◽  
Hard Tissues

Abstract Tooth plates of the chimaeroids, holocephalian fishes, are unique dental hard tissues. Unlike the teeth of other animals, the tooth plates are located on the roof of the mouth and in the lower jaw. Their tooth plates consist, to a large extent, of lightly mineralized tissue (osteodentin) and hypermineralized tissue (pleromin). Notably, the mineral phase of pleromin is whitlockite, while that of other animals is apatite. Dietary habits of chimaeroids and wearing features of their tooth plates suggest an extreme hardness of pleromin, but this has never been investigated. We examined the microhardness of the tooth plate of Chimaera phantasma and found that pleromin in the biting region was extremely hard, comparable with the hardness of mature tooth enamel, whereas the hardness of immature pleromin was lower than that of bovine dentin. The hardness of osteodentin, on the other hand, was equivalent to that of bovine dentin and almost the same throughout the tooth plate. Immature pleromin was sparsely packed with oval crystals of whitlockite and, as pleromin matures, the space between crystals was filled with small intercrystalline materials. The maturing process of pleromin could partly contribute to its remarkable hardness and have some implications for designing novel biomaterials.

scholarly journals A new short-necked chelid turtle from the Loncoche Formation (Late Campanian- Early Maastrichtian) Mendoza province, Argentina: Macro, microanatomy, and preliminary phylogenetic relationships

2015 ◽  
Author(s):  
Marcelo de la Fuente ◽  
Ignacio Maniel ◽  
Juan Marcos Jannello ◽  
Juliana Sterli ◽  
Bernardo González Riga ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Cancellous Bone ◽  
Phylogenetic Relationships ◽  
Cervical Vertebrae ◽  
Data Matrix ◽  
Appendicular Skeleton ◽  
Thin Sections ◽  
Lower Jaw ◽  
A New Species ◽  
Preliminary Phylogenetic Analysis

Background. The lower section of the Loncoche Formation (Late Campanian-Early Maastrichtian) outcropping at Ranquil-Có locality (Mendoza province, Argentina) has yielded a rich assemblage of vertebrates that was studied in 1995 by Gonzalez Riga. According to this author these vertebrate remains were found in a tidal paleoenvironment, resulting from transportation, mixing and deposition of continental remains mixed with those from near costal environments. Previously to these findings Jose F. Bonaparte recovered in 1990 a large turtle from the same locality and horizon. Methods. Remains of basicranium (basioccipital and basisphenoid), fragments of both quadrates, left opisthotic, a lower jaw, cervical vertebrae, one caudal vertebra, appendicular skeleton, a partial carapace and one almost complete plastron are preserved in MACN Pv M2. In order to explore the phylogenetic relationships of MACN Pv M2, this specimen was included in a data matrix built up by 48 characters and 17 taxa. One fragmentary costal plate was sampled for histological analysis. The bone microstructure of the thin sections was studied under light microscopy using normal and polarized lights. Results. The preliminary phylogenetic analysis suggests that MACN Pv M2 is nested in a clade also including Phrynops hilarii + Mesoclemmys nasuta + long-necked chelids. The pelvic girdle attached by suture to the shell in MACN Pv M2 and the synapomorphic characters such as splenial bone in the lower jaw, ilium extending over the eight costal and anterior margin of the suprapygal bones allow us to assign this specimen to Pleurodira Chelidae. The microanatomy of MACN Pv M2 shows a diploe structure as in other turtles. The internal cortex is equal or slowly thinner than the external one, and the cancellous bone occupy the main proportion (50-60%). The external cortex is composed of structural fibre bundles that extend parallel to the external surface and orient longitudinally and transversally to the progression of the elements. The cancellous bone is mostly well developed. The internal cortex consists of parallel-fibred bone that locally can grade into lamellar bone. Discussion. The unique combination of plesiomorphies (such as lateral mesoplastra, area articularis mandibularis concave, a short midline epiplastral suture, an anterior peripherals bones shorter than posterior ones) and autapomorphies (such as both rami of the lower jaw fused, extremely wide anterior plastral lobe, and a slightly epiplastral notch) recovered in this phylogenetic analysis allow to assigned MACN Pv M2 as a new species of short-necked chelid taxa. The histology of MACN Pv M2 shows features that suggest adaptation to the aquatic lifestyle (i.e., well vascularized external cortex, the vascularization of the internal cortex composed of scattered vascular canals and primary osteons of longitudinally orientation).

scholarly journals A new short-necked chelid turtle from the Loncoche Formation (Late Campanian- Early Maastrichtian) Mendoza province, Argentina: Macro, microanatomy, and preliminary phylogenetic relationships

2015 ◽  
Author(s):  
Marcelo de la Fuente ◽  
Ignacio Maniel ◽  
Juan Marcos Jannello ◽  
Juliana Sterli ◽  
Bernardo González Riga ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Cancellous Bone ◽  
Phylogenetic Relationships ◽  
Cervical Vertebrae ◽  
Data Matrix ◽  
Appendicular Skeleton ◽  
Thin Sections ◽  
Lower Jaw ◽  
A New Species ◽  
Preliminary Phylogenetic Analysis

Background. The lower section of the Loncoche Formation (Late Campanian-Early Maastrichtian) outcropping at Ranquil-Có locality (Mendoza province, Argentina) has yielded a rich assemblage of vertebrates that was studied in 1995 by Gonzalez Riga. According to this author these vertebrate remains were found in a tidal paleoenvironment, resulting from transportation, mixing and deposition of continental remains mixed with those from near costal environments. Previously to these findings Jose F. Bonaparte recovered in 1990 a large turtle from the same locality and horizon. Methods. Remains of basicranium (basioccipital and basisphenoid), fragments of both quadrates, left opisthotic, a lower jaw, cervical vertebrae, one caudal vertebra, appendicular skeleton, a partial carapace and one almost complete plastron are preserved in MACN Pv M2. In order to explore the phylogenetic relationships of MACN Pv M2, this specimen was included in a data matrix built up by 48 characters and 17 taxa. One fragmentary costal plate was sampled for histological analysis. The bone microstructure of the thin sections was studied under light microscopy using normal and polarized lights. Results. The preliminary phylogenetic analysis suggests that MACN Pv M2 is nested in a clade also including Phrynops hilarii + Mesoclemmys nasuta + long-necked chelids. The pelvic girdle attached by suture to the shell in MACN Pv M2 and the synapomorphic characters such as splenial bone in the lower jaw, ilium extending over the eight costal and anterior margin of the suprapygal bones allow us to assign this specimen to Pleurodira Chelidae. The microanatomy of MACN Pv M2 shows a diploe structure as in other turtles. The internal cortex is equal or slowly thinner than the external one, and the cancellous bone occupy the main proportion (50-60%). The external cortex is composed of structural fibre bundles that extend parallel to the external surface and orient longitudinally and transversally to the progression of the elements. The cancellous bone is mostly well developed. The internal cortex consists of parallel-fibred bone that locally can grade into lamellar bone. Discussion. The unique combination of plesiomorphies (such as lateral mesoplastra, area articularis mandibularis concave, a short midline epiplastral suture, an anterior peripherals bones shorter than posterior ones) and autapomorphies (such as both rami of the lower jaw fused, extremely wide anterior plastral lobe, and a slightly epiplastral notch) recovered in this phylogenetic analysis allow to assigned MACN Pv M2 as a new species of short-necked chelid taxa. The histology of MACN Pv M2 shows features that suggest adaptation to the aquatic lifestyle (i.e., well vascularized external cortex, the vascularization of the internal cortex composed of scattered vascular canals and primary osteons of longitudinally orientation).

Green Pigmentation in Human Teeth. A Stereomicroscopic Study

2014 ◽  
Vol 38 (4) ◽  
pp. 355-361 ◽  
Author(s):  
A Rakauskaite ◽  
G Juodzbalys ◽  
DH Pauza ◽  
M Cicciù
Keyword(s):  
Current Knowledge ◽  
Current Status ◽  
Primary Tooth ◽  
Human Teeth ◽  
Thin Sections ◽  
Dental Tissues ◽  
Microscopic Features ◽  
Proper Diagnosis ◽  
Uncommon Condition ◽  
Hard Dental Tissues

Green pigmentation in teeth is an uncommon condition associated with bilirubin deposits in hard dental tissues. Its occurrence can cause anxiety to both the child and parents and is not diagnosed easily by clinicians. The aim of this study is to analyze the current knowledge about the etiology, the intraoral alterations, and the macroscopic and microscopic features of green teeth pigmentation related to a high bilirubin levels. A primary tooth was extracted and manually sliced into 600 microns thin sections. The slenderized slices were examined with a light microscope AxioImager M1 to evaluate the microscopic teeth structure. The clinical characteristics of teeth may help in the diagnosis of current or past systemic diseases. Pediatricians should be able to quickly note the signs in order to perform the proper diagnosis. This study may help clinicians gain more knowledge about the current status of this uncommon pathology.

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