scholarly journals Sampling impacts the assessment of tooth growth and replacement rates in archosaurs: implications for paleontological studies

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9918
Author(s):  
Jens C.D. Kosch ◽  
Lindsay E. Zanno
Keyword(s):  
Dietary Habits ◽  
Small Sample ◽  
Formation Time ◽  
Alligator Mississippiensis ◽  
Central Axis ◽  
Tooth Replacement ◽  
Replacement Rate ◽  
Tooth Formation ◽  
Dental Tissues ◽  
Sampling Protocols

Dietary habits in extinct species cannot be directly observed; thus, in the absence of extraordinary evidence, they must be reconstructed with a combination of morphological proxies. Such proxies often include information on dental organization and function such as tooth formation time and tooth replacement rate. In extinct organisms, tooth formation times and tooth replacement rate are calculated, in part via extrapolation of the space between incremental lines in dental tissues representing daily growth (von Ebner Line Increment Width; VEIW). However, to date, little work has been conducted testing assumptions about the primary data underpinning these calculations, specifically, the potential impact of differential sampling and data extrapolation protocols. To address this, we tested a variety of intradental, intramandibular, and ontogentic sampling effects on calculations of mean VEIW, tooth formation times, and replacement rates using histological sections and CT reconstructions of a growth series of three specimens of the extant archosaurian Alligator mississippiensis. We find transect position within the tooth and transect orientation with respect to von Ebner lines to have the greatest impact on calculations of mean VEIW—a maximum number of VEIW measurements should be made as near to the central axis (CA) as possible. Measuring in regions away from the central axis can reduce mean VEIW by up to 36%, causing inflated calculations of tooth formation time. We find little demonstrable impact to calculations of mean VEIW from the practice of subsampling along a transect, or from using mean VEIW derived from one portion of the dentition to extrapolate for other regions of the dentition. Subsampling along transects contributes only minor variations in mean VEIW (<12%) that are dwarfed by the standard deviation (SD). Moreover, variation in VEIW with distance from the pulp cavity likely reflects idiosyncratic patterns related to life history, which are difficult to control for; however, we recommend increasing the number of VEIW measured to minimize this effect. Our data reveal only a weak correlation between mean VEIW and body length, suggesting minimal ontogenetic impacts. Finally, we provide a relative SD of mean VEIW for Alligator of 29.94%, which can be used by researchers to create data-driven error bars for tooth formation times and replacement rates in fossil taxa with small sample sizes. We caution that small differences in mean VEIW calculations resulting from non-standardized sampling protocols, especially in a comparative context, will produce inflated error in tooth formation time estimations that intensify with crown height. The same holds true for applications of our relative SD to calculations of tooth formation time in extinct taxa, which produce highly variable maximum and minimum estimates in large-toothed taxa (e.g., 718–1,331 days in Tyrannosaurus).

scholarly journals Relatively low tooth replacement rate in a sauropod dinosaur from the Early Cretaceous Ruyang Basin of central China

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12361
Author(s):  
Huali Chang ◽  
Hai-Lu You ◽  
Li Xu ◽  
Waisum Ma ◽  
Diansong Gao ◽  
...  
Keyword(s):  
Anatomical Study ◽  
Central China ◽  
Tooth Replacement ◽  
Replacement Rate ◽  
Tooth Formation ◽  
Single Crown ◽  
Feeding Mechanics ◽  
Data Points ◽  
Few Data ◽  
Rostral Portion

Tooth replacement rate is an important feature related to feeding mechanics and food choices for dinosaurs. However, only a few data points are available for sauropod dinosaurs, partially due to rarity of relevant fossil material. Four somphospondylan sauropod species have been recovered from the Lower Cretaceous Aptian–Albian Haoling Formation in the Ruyang Basin, Henan Province of central China, but no cranial material has been reported except for a single crown. Here we report the discovery of the rostral portion of a left dentary with replacement teeth in its first five alveoli. Comparative anatomical study shows the partial dentary can be assigned to a member of early diverging somphospondylans. The non-destructive tooth length-based approach to estimating tooth formation time and replacement rate is adopted here. The estimated tooth replacement rate is 76 days, faster than that of Brachiosaurus (83 days) and much lower than typical late diverging lithostrotian titanosaurians (20 days). Thus, this discovery adds an intermediate tooth replacement rate in the evolution of titanosauriform sauropods and supports the idea that evolution of tooth replacement rate is clade-specific. This discovery also provides more information to understand the Ruyang sauropod assemblage, which includes one of the most giant dinosaurs to have walked our Earth (Ruyangosaurus giganteus).

scholarly journals The Effects of Premature Tooth Extraction and Damage on Replacement Timing in the Green Iguana

2020 ◽  
Vol 60 (3) ◽  
pp. 581-593
Author(s):  
Kirstin S Brink ◽  
Ping Wu ◽  
Cheng-Ming Chuong ◽  
Joy M Richman
Keyword(s):  
Tooth Extraction ◽  
Tooth Development ◽  
Tooth Wear ◽  
X Rays ◽  
Tooth Replacement ◽  
Green Iguana ◽  
Dental Tissues ◽  
Functional Tooth ◽  
Green Iguanas ◽  
Replacement Cycle

Synopsis Reptiles with continuous tooth replacement, or polyphyodonty, replace their teeth in predictable, well-timed waves in alternating tooth positions around the mouth. This process is thought to occur irrespective of tooth wear or breakage. In this study, we aimed to determine if damage to teeth and premature tooth extraction affects tooth replacement timing long-term in juvenile green iguanas (Iguana iguana). First, we examined normal tooth development histologically using a BrdU pulse-chase analysis to detect label-retaining cells in replacement teeth and dental tissues. Next, we performed tooth extraction experiments for characterization of dental tissues after functional tooth (FT) extraction, including proliferation and β-Catenin expression, for up to 12 weeks. We then compared these results to a newly analyzed historical dataset of X-rays collected up to 7 months after FT damage and extraction in the green iguana. Results show that proliferation in the dental and successional lamina (SL) does not change after extraction of the FT, and proliferation occurs in the SL only when a tooth differentiates. Damage to an FT crown does not affect the timing of the tooth replacement cycle, however, complete extraction shifts the replacement cycle ahead by 4 weeks by removing the need for resorption of the FT. These results suggest that traumatic FT loss affects the timing of the replacement cycle at that one position, which may have implications for tooth replacement patterning around the entire mouth.

scholarly journals Improved Application of Bomb Carbon in Teeth for Forensic Investigation

Radiocarbon ◽  
2010 ◽  
Vol 52 (2) ◽  
pp. 706-716 ◽  
Author(s):  
N Wang ◽  
C D Shen ◽  
P Ding ◽  
W X Yi ◽  
W D Sun ◽  
...  
Keyword(s):  
Organic Matter ◽  
Tooth Enamel ◽  
Isotopic Fractionation ◽  
Formation Time ◽  
Birth Date ◽  
Forensic Investigation ◽  
Enamel Formation ◽  
Data Set ◽  
Tooth Formation ◽  
The Difference

While radiocarbon is widely applied in dating ancient samples, recent studies reveal that 14C concentrations in modern samples can also yield precise ages due to the atmospheric testing of thermonuclear devices between 1950 and 1963. 14C concentrations in both enamel and organic matter of 13 teeth from 2 areas in China were examined to evaluate and improve this method of forensic investigation. Choosing enamel near the cervix of the tooth can reduce the error caused by the difference between the sample formation time and whole enamel formation time because tooth enamel formations take a long time to complete. A proper regional data set will be helpful to get an accurate result when calculating the age of the sample (T1) by the CALIBomb program. By subtracting the enamel formation time (t), the birth date of an individual (T2) can be confirmed by enamel F14C from 2 teeth formed at different ages. Calculated enamel formation dates by 14C concentration are basically consistent with corresponding actual values, with a mean error of 1.9 yr for all results and 0.2 yr for the samples formed after AD 1960. This method is more effective for dating samples completed after AD 1960. We also found that 14C concentrations in organic matter of tooth roots are much lower than atmospheric concentrations in root formation years, suggesting that the organic material keeps turning over even after tooth formation is complete. This might be a potential tool for identification of death age to extract a proper component for 14C dating. We also observed that δ13C values between hydroxyapatite and organic matter indicate that isotopic fractionation during the biomineralization is 8–9%‰ more positive in mineral fractions than in organic matter.

scholarly journals Sanjad-Sakati Syndrome Dental Management: A Case Report

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
Hisham Y. El Batawi
Keyword(s):  
Health Education ◽  
General Anesthesia ◽  
Dietary Habits ◽  
Dental Treatment ◽  
Dental Health ◽  
Genetic Disorder ◽  
Growth Failure ◽  
Dental Tissues ◽  
Dental Management ◽  
Nutritional Needs

Sanjad-Sakati syndrome (SSS) is a rare genetic disorder with autosomal recessive pattern of inheritance characterized by hypoparathyroidism, sever growth failure, mental retardation, susceptibility to chest infection, and dentofacial anomalies. A child with SSS was referred to the dental departmentseeking dental help for sever dental caries which was attributed to his dietary habits and quality of dental tissues. Full restorative rehabilitation was done under general anesthesia. Two years later, the child presented with recurrent caries affecting uncrowned teeth. High carries recurrence rate was blamed for the nutritional habits endorsed by the parents. Only steel crowned teeth survived such hostile oral environment which suggested shifting of treatment strategy towards full coverage restorations instead of classical cavity preparations and fillings during a second attempt for dental treatment under general anesthesia and for the dental treatment of two cousins of the same child. The author recommends effective health education for parents including the nature of their child’s genetic disorder, nutritional needs, and dental health education to improve the life style of such children.

The dentition of the narrownose smooth-hound shark, Mustelus schmitti

2014 ◽  
Vol 65 (8) ◽  
pp. 688 ◽  
Author(s):  
Mauro Belleggia ◽  
Daniel E. Figueroa ◽  
Claudia Bremec
Keyword(s):  
Dental Formula ◽  
Tooth Replacement ◽  
Replacement Rate ◽  
Length Difference ◽  
Labial Side ◽  
Jaw Position ◽  
Established Technique ◽  
Trawl Surveys ◽  
Tooth Length ◽  
Mustelus Schmitti

The present study provides a quantitative and qualitative analysis on the dentition of Mustelus schmitti, and estimates the tooth-replacement rate. In total, 47 males and 56 females of M. schmitti were collected on scientific trawl surveys conducted by the National Institute of Fisheries Research and Development (INIDEP) in Argentina during the months of November 2007, November 2008 and December 2008. The dental laminas were extracted from the jaw cartilage and attached to onionskin paper for dehydration treatment, maintaining the original jaw position. Tooth replacement rate was estimated following established methods used for fossil sharks, instead of the established technique of clipping teeth, based on the premise that tooth length within each row decreases from the lingual to the labial side of the jaw as a consequence of wear. The length difference between consecutive teeth in four representative rows should be proportional to the tooth-replacement rate. Mustelus schmitti exhibited homodont dentition, where teeth were similar in shape or design, and are arranged in a semi-pavement-like dentition. The dental formula was 47-63/50-63 for juveniles and 50-77/50-69 for adult specimens. The estimated mean replacement rate was 4 days series–1.

scholarly journals SOME THOUGHTS ON INTERSPECIFIC MANDIBULAR MORPHOLOGY IN FOSSIL AND MODERN ALLIGATOR

2021 ◽  
Author(s):  
Jeremy Stout
Keyword(s):  
Fossil Record ◽  
Small Sample Size ◽  
Morphological Characters ◽  
Small Sample ◽  
Alligator Mississippiensis ◽  
Early Pleistocene ◽  
Species Determination ◽  
Fossil Species ◽  
Wide Variability ◽  
Anterior Extent

Alligator is diagnosed in the fossil record using discrete morphological characters.  These characters are used with systematic analyses to determine hypothetical phylogenetic relationships.  Examined here are two such characters for applicability in fossil species determination and relationship. One is the curvature of the dentary between the fourth and tenth alveoli (observed in several taxa), while the other is a further investigation into the anterior extent of the splenial (in modern Alligator mississippiensis and the early Pleistocene A. hailensis).  In a small sample size, the curvature of the dentary exhibits wide variability in character states both intraspecifically and interspecifically, bringing into question its utility in fossil crocodylian systematic applications.  The anatomy of the anterior extent of the splenial is phylogenetically informative, and a new method for inferring its presence as a basal or derived state (as a scar on the dentary) is described.

scholarly journals TEETH EXTRACTION WITH ROOT DELACERATION ON THE ORTHODONTIC INDICATIONS

2019 ◽  
Vol 31 (4) ◽  
pp. 853-857
Author(s):  
Pavel Stanimirov ◽  
Greta Yordanova
Keyword(s):  
Clinical Case ◽  
Treatment Approach ◽  
Tooth Replacement ◽  
Central Incisor ◽  
Tooth Formation ◽  
X Ray ◽  
Crown Root ◽  
Cystic Formation ◽  
Dental Eruption ◽  
Teeth Extraction

Dilaceration of root is a phenomenon that changes the axial axis of the tooth at an angle, at the crown or root’s level. The actual mechanical obstructions in the way of dental eruption can be: root canal infections in the neighborhood tissues, development of the ectopically located dental germs and lack of space for them, anatomically dense structures, ankylosis temporary tooth, and so on. The purpose of our study is to analyze the causes of dental root dilaceration in patients, the first with the upper central incisor affected, and the second with the lower first premolar affected, as well as the approaches to their orthodontic treatment. In the first clinical case, the root dilaceration of the lower right first premolar is due to the development of a large cystic formation from a devialized lower right first temporary molar. In the second clinical case a rectangular upper left central incisor with a delacerated apex and a reversed direction of a crown-root was found, with the crown near the nasal cavity. The most accurate morphology of the affected teeth may be performed by a CBCT study. The treatment approach in both patients is extraction of the tooth with root dilaceration. In the first clinical case, the mechanical force that compresses and changes the direction of tooth formation is the cystic collection. In the second clinical case, the real cause of the delaceration and inverted direction of the germ of an upper left central incisor is not clear. A trauma of temporary teeth is often overlooked by parents. An early and timely intervention can save patients from the consequences of this trauma. Clinicians, who treat such as cases should use pre-diagnostic means such as CBCT to plan the treatment. Parents and dentists should devote particular attention to the deviated temporary teeth which shift is delayed. It is necessary to carry check-ups out at the age of tooth replacement, obligatory with X-ray followed by the consultation with an orthodontist.

Eliminating Laser Induced Elemental U-Pb Fractionation using low sample volume multi-shot ablation protocols

2020 ◽  
Author(s):  
Eoghan Corbett ◽  
Antonio Simonetti ◽  
Phil Shaw ◽  
Loretta Corcoran ◽  
Quentin Crowley ◽  
...  
Keyword(s):  
Laser Radiation ◽  
Laser Ablation ◽  
High Frequency ◽  
Dimensional Space ◽  
Sampling Site ◽  
Small Sample ◽  
Incident Laser ◽  
Incident Laser Radiation ◽  
Icp Ms ◽  
Sampling Protocols

&lt;p&gt;The interaction of incident laser radiation and sample substrate is complex and difficult to predict. Natural zircons areoften both structurally and chemically heterogeneous in 3-dimensional space. Encountering growth-related, structural micro-heterogeneities, inclusions and chemical complexities is almost inevitable when employing &amp;#8216;conventional&amp;#8217; static, high-frequency laser sampling protocols often lasting several tens of seconds at a time.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;A multi-shot approach to laser ablation by contrast implements a minimal sample exposure time to incident laser radiation by applying multiple 1 Hz shots in delayed succession to a single sampling site. This process can be conceptualised as a &amp;#8220;slowing down&amp;#8221; of a high-frequency (10-20 Hz) static Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) analysis. Each laser pulse applied in this manner, produces signal peak which is distinct albeit transient. The ability to integrate and collate signal pulses for a small number of consecutive laser shots (10-30 shots), as opposed to continuously pulsing the laser, produces highly precise age determinations (&lt;1% reproducibility, 2slevel) on small sample volumes (~695&amp;#181;m&lt;sup&gt;3 &lt;/sup&gt;on 91500 zircon standard). The multi-shot LA-ICP-MS protocol employed here effectively eliminates &amp;#8216;downhole&amp;#8217; fractionation as the resultant craters are extremely shallow (as shallow as ~553nm on 91500 zircon standard) and maintain an aspect ratio of &lt;&lt;1. Further benefits include a reduced probability of thermally induced effects (e.g., substrate melting), plasma loading, and the potential for signal mixing (with depth) in a heterogeneous sample.&lt;/p&gt;

scholarly journals Enamel formation and growth in non-mammalian cynodonts

2018 ◽  
Vol 5 (5) ◽  
pp. 172293 ◽  
Author(s):  
Rachel N. O'Meara ◽  
Wendy Dirks ◽  
Agustín G. Martinelli
Keyword(s):  
Growth Rates ◽  
Polarized Light ◽  
Growth Patterns ◽  
Juvenile Growth ◽  
Tooth Replacement ◽  
Replacement Rate ◽  
Adult Growth ◽  
Evolution Of Mammals ◽  
Additional Explanation ◽  
Incremental Lines

The early evolution of mammals is associated with the linked evolutionary origin of diphyodont tooth replacement, rapid juvenile growth and determinate adult growth. However, specific relationships among these characters during non-mammalian cynodont evolution require further exploration. Here, polarized light microscopy revealed incremental lines, resembling daily laminations of extant mammals, in histological sections of enamel in eight non-mammalian cynodont species. In the more basal non-probainognathian group, enamel extends extremely rapidly from cusp to cervix. By contrast, the enamel of mammaliamorphs is gradually accreted, with slow rates of crown extension, more typical of the majority of non-hypsodont crown mammals. These results are consistent with the reduction in dental replacement rate across the non-mammalian cynodont lineage, with greater rates of crown extension required in most non-probainognathians, and slower crown extension rates permitted in mammaliamorphs, which have reduced patterns of dental replacement in comparison with many non-probainognathians. The evolution of mammal-like growth patterns, with faster juvenile growth and more abruptly terminating adult growth, is linked with this reduction in dental replacement rates and may provide an additional explanation for the observed pattern in enamel growth rates. It is possible that the reduction in enamel extension rates in mammaliamorphs reflects an underlying reduction in skeletal growth rates at the time of postcanine formation, due to a more abruptly terminating pattern of adult growth in these more mammal-like, crownward species.

Sign in / Sign up

Export Citation Format

Share Document