scholarly journals A Reevaluation of Sexual Dimorphism in the Postcranium of the Chasmosaurine Ceratopsid Chasmosaurus belli (Dinosauria: Ornithischia)

2006 ◽  
Vol 120 (4) ◽  
pp. 403 ◽  
Author(s):  
Jordan C. Mallon ◽  
Robert B. Holmes
Keyword(s):  
Sexual Dimorphism ◽  
Fossil Record ◽  
Statistical Significance ◽  
Separate Species ◽  
Moderate Amount ◽  
Show Evidence ◽  
Dinosaur Park Formation

The sexual dimorphism attributed to Chasmosaurus belli by Sternberg (1927) is revisited and reevaluated. A reexamination of the two specimens originally considered by Sternberg reveals that they are less complete than first suggested, with only a moderate amount of overlapping material between them. Only a few of the postcranial elements (humeri, sternal plates, and presacral vertebrae) show evidence of dimorphism, the significance of which is either doubtful or equivocal. Instead of representing sexual dimorphs, it is likely that the two specimens belong to separate species, C. belli and C. russelli, as evidenced by their distinct frill morphologies and by their stratigraphic segregation within the Dinosaur Park Formation of Alberta. These findings emphasize the need to remain sceptical about claims advocating sexual dimorphism in the fossil record in the absence of statistical significance or stratigraphic control.

scholarly journals Comparison of the Cerumenolytic Activities of New and Currently Used Agents

2021 ◽  
pp. 014556132098606
Author(s):  
Nguyen Quynh Anh ◽  
Pawin Numthavaj ◽  
Thongchai Bhongmakapat
Keyword(s):  
Salicylic Acid ◽  
Sodium Bicarbonate ◽  
Potassium Hydroxide ◽  
Glycolic Acid ◽  
Statistical Significance ◽  
In Vitro Study ◽  
Distilled Water ◽  
Moderate Amount ◽  
All Solutions

Objectives: This study compared the cerumen dissolution activities of 7.5% sodium bicarbonate, 5% potassium hydroxide, 10% lactic acid, 3% salicylic acid, 10% glycolic acid, and distilled water. Methods: An in vitro study was conducted with 36 cerumen samples. The cerumenolytic activities of the 6 agents were assessed by recording the degree of cerumen disintegration using digital photography at 15 minutes, 30 minutes, 1 hour, 2 hours, and 12 hours. The undissolved cerumen that remained after 12 hours was removed from the solutions and weighed after drying. Results: Potassium hydroxide showed the fastest cerumenolytic activity, dissolving a moderate amount of cerumen at 30 minutes, while glycolic acid and salicylic acid caused no visible changes in the cerumen samples. Samples treated with potassium hydroxide and sodium bicarbonate exhibited higher degrees of disintegration compared to samples treated with distilled water (odds ratio and 95% CI: 273.237 [0.203-367 470.4] and 1.129 [0.002-850.341], respectively). The greatest reduction in cerumen weight was associated with the use of sodium bicarbonate; however, this result did not reach statistical significance. Conclusions: Among the solutions tested, 5% potassium hydroxide showed the fastest dissolution activity, yielding moderate disintegration within only 30 minutes. In terms of residual cerumen weight within 12 hours, all solutions exhibited equivalent effectiveness in the disintegration of cerumen.

Anatomical, morphometric, and stratigraphic analyses of theropod biodiversity in the Upper Cretaceous (Campanian) Dinosaur Park Formation

2021 ◽  
pp. 1-15
Author(s):  
Thomas M. Cullen ◽  
Lindsay Zanno ◽  
Derek W. Larson ◽  
Erinn Todd ◽  
Philip J. Currie ◽  
...  
Keyword(s):  
High Resolution ◽  
North America ◽  
Fossil Record ◽  
Upper Cretaceous ◽  
Environmental Changes ◽  
Morphometric Analyses ◽  
Variable Distribution ◽  
Taxic Diversity ◽  
Dinosaur Park Formation ◽  
Broad Scale

The Dinosaur Park Formation (DPF) of Alberta, Canada, has produced one of the most diverse dinosaur faunas, with the record favouring large-bodied taxa, in terms of number and completeness of skeletons. Although small theropods are well documented in the assemblage, taxonomic assessments are frequently based on isolated, fragmentary skeletal elements. Here we reassess DPF theropod biodiversity using morphological comparisons, high-resolution biostratigraphy, and morphometric analyses, with a focus on specimens/taxa originally described from isolated material. In addition to clarifying taxic diversity, we test whether DPF theropods preserve faunal zonation/turnover patterns similar to those previously documented for megaherbivores. Frontal bones referred to a therizinosaur (cf. Erlikosaurus), representing among the only skeletal record of the group from the Campanian–Maastrichtian (83–66 Ma) fossil record of North America, plot most closely to troodontids in morphospace, distinct from non-DPF therizinosaurs, a placement supported by a suite of troodontid anatomical frontal characters. Postcranial material referred to cf. Erlikosaurus in North America is also reviewed and found most similar in morphology to caenagnathids, rather than therizinosaurs. Among troodontids, we document considerable morphospace and biostratigraphic overlap between Stenonychosaurus and the recently described Latenivenatrix, as well as a variable distribution of putatively autapomorphic characters, calling the validity of the latter taxon into question. Biostratigraphically, there are no broad-scale patterns of faunal zonation similar to those previously documented in ornithischians from the DPF, with many theropods ranging throughout much of the formation and overlapping extensively, possibly reflecting a lack of sensitivity to environmental changes, or other cryptic ecological or evolutionary factors.

scholarly journals Lophyra flexuosa (Fabricius, 1787) (Coleoptera: Cicindelidae) in desert countries: morphological variability in geographic aspect as potential beginning of speciation?

2019 ◽  
Vol 2 ◽  
Author(s):  
Radomir Jaskuła ◽  
Axel Schwerk ◽  
Mateusz Płóciennik
Keyword(s):  
Sexual Dimorphism ◽  
Western Europe ◽  
Morphological Variability ◽  
Total Body Length ◽  
Head Width ◽  
Morphometric Traits ◽  
Altitudinal Distribution ◽  
Separate Species ◽  
Body Sizes ◽  
Total Body

Lophyra flexuosa is one of only several eurytopic tiger beetles species known from Palearctic realm. Its geographical distribution shows several populations that are spread from the Iberian Peninsula and Morocco, across some regions of south-western Europe and northern Africa to Israel and Syria. The species is characterized by long phenological activity, wide altitudinal distribution, and occurs in the highest number of habitats among all Cicindelidae known from Maghreb region. In the present study the geographical variation in morphology and sexual dimorphism in north African populations of L. flexuosa was studied. In total 52 samples with over 700 specimens were collected including 20 samples in Morocco and 32 in Tunisia. To test the variation in morphometric traits measurements of eight body parameters were taken from all males (383) and females (352) including right mandible length, length of head, width of head, length of pronotum, maximum pronotum width, length of elytra, maximum elytra width, and total body length. We discovered significant sexual dimorphism expressed by larger body size of females and longer mandibles in males, what can be explained by different roles of particular sexes in courtship. Moreover, we recorded significant differences in body sizes between western and eastern Maghreb populations which can suggest genetic isolation between these populations. As the species is related to habitats placed close to water reservoirs, which in the desert countries are under significant human pressure (including climate change), we expect an reduction of habitats occupied by this taxon. Therefore, the geographic morphological variability that we observe today in the tiger beetle Lophyra flexuosa may lead to speciation and creation of separate species in the future.

scholarly journals ANTHROPOMETRY OF THE EXTERNAL EAR AMONG ADULT IJAWS IN BAYELSA STATE OF NIGERIA

2019 ◽  
Vol 5 (1) ◽  
pp. 75-83
Author(s):  
E. I. Edibamode ◽  
K. Mordi ◽  
L. K. David ◽  
A. M. Eghoi
Keyword(s):  
Sexual Dimorphism ◽  
Statistical Significance ◽  
External Ear ◽  
Chi Square ◽  
Mean Values ◽  
Chi Square Test ◽  
Males And Females ◽  
And Gender ◽  
The Right ◽  
Chi Square Analysis

Background. External ear measurement is of utmost importance in reconstructive surgeries. Objectives. The present study is aimed at ascertaining sexual dimorphism in external ear anthropometry and ear lobe attachments among adults Ijaws in Bayelsa, Nigeria. Methods. A total of 112 adults within the age range of 18-50 yrs, who met the inclusion criteria, were involved in the study. Four linear dimensions of the ear, which are ear length (EL), ear width (EW), lobular length (LL) and lobular width (LW), were measured for both genders. The lobular attachment for both ears for males and females were also examined and results recorded. These data were subjected to Student t-test, Chi-square test, and Pearson’s correlation using SPSS version 20.0. Results. The mean values for EL, EW, LL, and LW for the left auricle in the males and females were 58.14±0.60, 27.41±0.37, 14.47±0.27, 13.50±0.34 and 57.90±0.16, 27.45±0.65, 15.41±0.31, 13.43±0.38 respectively. However, for the right auricle in the males and females, the values were 58.40±0.45, 28.21±0.68, 14.32±0.31, 13.04±0.32, and 56.66±1.10, 27.51±0.65, 15.58±0.29, 13.28±0.34 respectively. The left and right lobular length were the only parameters that proved statistical significance (p<0.05) in females compare to males. Pearson’s correlations between right and left sides for each of the parameters were positive and significant. Chi-square analysis revealed no significant relationship (p>0.05) between earlobe attachments and gender. Conclusions. Sexual dimorphism was thus established in the Ijaw population as regards lobular length dimensions. It is believed that the results of this study would be very useful for ear morphology and reconstructive surgeries.

scholarly journals Determining sexual dimorphism in frog measurement data: integration of statistical significance, measurement error, effect size and biological significance

2005 ◽  
Vol 77 (1) ◽  
pp. 45-76 ◽  
Author(s):  
Lee-Ann C. Hayek ◽  
W. Ronald Heyer
Keyword(s):  
Sexual Dimorphism ◽  
Measurement Error ◽  
Effect Size ◽  
Statistical Significance ◽  
Measurement Data ◽  
Biological Significance ◽  
Effect Sizes ◽  
Statistical Hypothesis ◽  
Multivariate Techniques ◽  
Error Index

Several analytic techniques have been used to determine sexual dimorphism in vertebrate morphological measurement data with no emergent consensus on which technique is superior. A further confounding problem for frog data is the existence of considerable measurement error. To determine dimorphism, we examine a single hypothesis (Ho = equal means) for two groups (females and males). We demonstrate that frog measurement data meet assumptions for clearly defined statistical hypothesis testing with statistical linear models rather than those of exploratory multivariate techniques such as principal components, correlation or correspondence analysis. In order to distinguish biological from statistical significance of hypotheses, we propose a new protocol that incorporates measurement error and effect size. Measurement error is evaluated with a novel measurement error index. Effect size, widely used in the behavioral sciences and in meta-analysis studies in biology, proves to be the most useful single metric to evaluate whether statistically significant results are biologically meaningful. Definitions for a range of small, medium, and large effect sizes specifically for frog measurement data are provided. Examples with measurement data for species of the frog genus Leptodactylus are presented. The new protocol is recommended not only to evaluate sexual dimorphism for frog data but for any animal measurement data for which the measurement error index and observed or a priori effect sizes can be calculated.

scholarly journals ROLE OF SACRUM IN SEX DETERMINATION IN WEST BENGAL POPULATION

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
Ujwala Bhanarkar ◽  
Baishakhi Koley
Keyword(s):  
Sexual Dimorphism ◽  
Sex Determination ◽  
West Bengal ◽  
Statistical Significance ◽  
Transverse Diameter ◽  
Medical Sciences ◽  
Curvature Index ◽  
Degree Of Certainty

Background: Sex classification of a bone is possible with a degree of certainty only if it can be compared to a series of bones of known sexual dimorphism. Different parameters and indices are available based on which the sex can be determined using sacrum. Thus, it always attracted the attention of the medico-legal experts for establishing the sex, because of its contribution to pelvic girdle and associated functional sex differences. Objective: Study the sexual dimorphism and regional differences of the varied features of the sacrum in West Bengal population and compare the significant anthropometric indices with similar observations across India. Material and method: The study comprised of 50 adult sacra (35 male and 15 female), obtained from the department of anatomy and department of forensic medicine of ICARE Institute of Medical Sciences and Research and Haldia Institute of Dental Sciences and Research, Haldia, West Bengal. Different parameters viz. mid ventral straight length, mid ventral curved length, ventral straight breadth, transverse diameter of base, transverse diameter of body of S1, antero-posterior diameter of body of S1, breadth of alae were measured and indices viz. sacral index, longitudinal curvature index and corporobasal index were calculated and statistically analyzed. Result: Sacral index was found to be the most useful criterion for identification of sex followed by breadth of alae, corporobasal index and the ventral straight breadth. Conclusion: In the present study, out of the eleven parameters of the sacrum, seven parameters yielded statistical significance between the two sexes. Therefore, it can be concluded that sex determination of the sacrum with 100% accuracy may possible only when maximum number of parameters are taken into consideration. Keywords: Sacrum, sexual dimorphism, sacral parameters, sacral index

First report of protoceratopsians (Neoceratopsia) from the Late Cretaceous Judith River Group, Alberta, Canada

1998 ◽  
Vol 35 (7) ◽  
pp. 820-826 ◽  
Author(s):  
Michael J Ryan ◽  
Philip J Currie
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Fossil Record ◽  
Coastal Environments ◽  
First Report ◽  
Skeletal Material ◽  
First Occurrence ◽  
Dinosaur Park Formation ◽  
Milk River Formation

Protoceratopsians are best known in North America from associated skeletal material of Montanoceratops from the early Maastrichtian of Montana and Campanian of Alberta and Leptoceratops from the late Maastrichtian of Alberta and Wyoming. We report here the first occurrence of protoceratopsian elements from the middle Campanian (Dinosaur Park Formation) of Alberta. The specimens consist of a fragmentary right dentary and an almost complete left dentary which can be referred to Leptoceratops sp. Recent examination of Albertan microvertebrate material has identified cf. protoceratopsians teeth from the latest Santonian (Milk River Formation), extending the record of Albertan protoceratopsians back almost 20 million years. The rarity of these small ornithischians in the fossil record of Alberta may have been due to ecological exclusion from the wet, coastal environments that were preferred by the larger, more abundant ceratopsids.

scholarly journals The ander's organ: a mechanism for anti-predator ultrasound in a relict orthopteran

2020 ◽  
pp. jeb.237289
Author(s):  
Charlie Woodrow ◽  
Kevin A. Judge ◽  
Christian Pulver ◽  
Thorin Jonsson ◽  
Fernando Montealegre-Z
Keyword(s):  
Sexual Dimorphism ◽  
Fossil Record ◽  
Peak Frequency ◽  
Anatomical Location ◽  
Term Survival ◽  
Extinct Species ◽  
The Family ◽  
Predator Defence ◽  
Predator Evasion

The use of acoustics in predator evasion is a widely reported phenomenon amongst invertebrate taxa, but the study of ultrasonic anti-predator acoustics is often limited to the prey of bats. Here, we describe the acoustic function and morphology of a unique stridulatory structure in the relict orthopteran Cyphoderris monstrosa (Ensifera, Hagloidea): the Ander's organ. This species is one of just eight remaining members of the family Prophalangopsidae, a group with a fossil record of over 90 extinct species widespread during the Jurassic. We reveal that the sound produced by this organ has the characteristics of a broadband ultrasonic anti-predator defence, with a peak frequency of 58±15.5 kHz and a bandwidth of 50 kHz (at 10 dB below peak). Evidence from sexual dimorphism, knowledge on hearing capabilities and assessment of local predators, suggest the signal likely targets ground-dwelling predators. Additionally, we reveal a previously undescribed series of cavities underneath the organ that likely function as a mechanism for ultrasound amplification. Morphological structures homologous in both appearance and anatomical location to the Ander's organ are observed to varying degrees in 4 of the 7 other extant members of this family, with the remaining 3 yet to be assessed. Therefore, we suggest that such structures may either be more widely present in this ancient family than previously assumed, or have evolved to serve a key function in the long-term survival of these few species, allowing them to outlive their extinct counterparts.

scholarly journals OCENA DYMORFIZMU PŁCIOWEGO WSKAŹNIKA DŁUGOŚCI PALCÓW (2D:4D)

2016 ◽  
Vol 60 (1) ◽  
Author(s):  
Maciej Mularczyk ◽  
Angelika Ziętek-Czeszak ◽  
Zbigniew Ziętek
Keyword(s):  
Sexual Dimorphism ◽  
Statistical Significance ◽  
Length Ratio ◽  
Significance Level ◽  
Finger Length ◽  
Fourth Finger ◽  
Males And Females ◽  
The Difference ◽  
The Right ◽  
Finger Length Ratio

Introduction: Studies on many populations have shown that the length of the second finger (2D) compared to the fourth (4D), expressed as the finger length ratio (2D:4D), might be characteristic for sexual dimorphism. It was also found that the values of 2D:4D differ significantly between examined populations. It is thought that the value of 2D:4D is determined in early foetal life under the influence of genetic factors and the strong influence of sex hormones. It has been proven that the values of 2D:4D are related to, for instance, sexual orientation, and artistic and sporting ability. Recently, increasing interest in the clinical significance of finger length ratio in the diagnosis of somatic and mental disorders has been observed. For example, it was found that values of 2D:4D in individuals suffering from congenital adrenal hyperplasia or autism were significantly lower compared to healthy subjects. The aim of the study was to determine sexual dimorphism in finger length ratio among representatives of the Polish population.Materials and methods: The study group comprised 115 people (57 females and 58 males). Anthropometric measurements were taken from the second and fourth finger of the right and left hands – from the point of dactylion (da) to pseudophalangion (pph) using analogue callipers. We calculated the significance of differences in 2D:4D between males and females separately for the right and left hands.Results: In both hands mean 2D:4D values were lower in males than in females. The difference in the right hand reached the statistical significance level with p < 0.05.Conclusions: Among the subjects from the examined population the 2D:4D ratio shows trends characteristic for sexual dimorphism.

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