Effects of concurrent aerobic and strength training in women diagnosed with non-metastatic breast cancer: a systematic review and meta-analysis.

PURPOSE: To investigate the potential impact of concurrent aerobic and strength training (CT) on women diagnosed with breast cancer. METHODS: Articles published in English and indexed in the PubMed, Web of Science, SPORTDiscus, The Cochrane Library, PsycINFO, EMBASE, and CINAHL Plus databases from their inception to 12 December 2023 were searched. Eligible studies were randomized controlled trials that involved CT and assessed cardiorespiratory fitness, cancer-related fatigue, and quality of life (QoL) using specialized tools. Subgroup analyses were conducted as per treatment status and characteristics. Risk of bias was evaluated with the Cochrane risk-of-bias tool (RoB 2.0). RESULTS: This study included 29 studies involving 2071 participants. CT was found to significantly improve patients' cardiorespiratory fitness (weighted mean difference = 4.24 mL/kg/min, 95% confidence interval (CI) = 1.93-6.55, P < 0.001), cancer-related fatigue (standardized mean difference (SMD) = - 0.74, 95% CI = - 1.05 to - 0.44, P < 0.001), and QoL (SMD = 0.76, 95% CI = 0.50-1.01, P < 0.001). The analysis of secondary outcomes found that CT could significantly improve patients' body composition, anxiety, pain, sleep disorders, and anorexia and enhance upper and lower limb muscle strength, but was ineffective on depression. CONCLUSION: For women with breast cancer, CT significantly enhances cardiorespiratory fitness, alleviates cancer-related fatigue, and improves QoL. The health benefits of CT are inferior in the postmenopausal cohort compared to the overall study population. IMPLICATIONS FOR CANCER SURVIVORS: CT is advisable for female breast cancer survivors due to its significant effectiveness in mitigating cancer-related fatigue, enhancing cardiorespiratory fitness, and improving the QoL.

Effects of exercise on depression and anxiety in postmenopausal women: a pairwise and network meta-analysis of randomized controlled trials.

BACKGROUND: Exercise has been identified as a promising non-pharmacological therapy for the management of depression, but there is still controversy over which type is most effective. We aimed to compare and rank the types of exercise that improve depression in postmenopausal women by quantifying information from randomized controlled trials (RCTs). METHODS: The PubMed, Web of Science, SPORTDiscus, CNKI, The Cochrane Library, PsycINFO, EMBASE, and CINAHL Plus databases were searched to identify articles published from inception to 1 March 2024 reporting RCTs that examined the effectiveness of exercise on depression in postmenopausal women. The risk of bias was assessed using the revised Cochrane risk-of-bias tool for RCTs. The quality of the evidence for each comparison was graded using the online confidence in network meta-analysis tool (CINeMA). Standardized mean differences (SMDs) were calculated using the mean and standard deviation of pre-to-post intervention changes and then pooled using a random effects model in a pairwise meta-analysis using Review Manager 5.4. Then, a frequentist network meta-analysis was conducted using a random effects model was conducted to evaluate the efficacy of different exercise types using the network package of Stata 15. RESULTS: This study included 26 studies involving 2,170 participants. The pairwise meta-analysis revealed that exercise had a significant positive effect on depression in postmenopausal women (SMD = -0.71, 95% confidence interval [CI] = -0.94 to -0.48; I2 = 78%). The network meta-analysis revealed that mind-body exercise (SMD = -0.97, 95% CI = -1.28 to -0.67), aerobic exercise (SMD = -0.58, 95% CI = -0.88 to -0.27) and multicomponent exercise (SMD = -0.57, 95% CI = -1.15 to -0.002) significantly reduced depression compared to the control intervention. Mind-body exercise had the highest probability of being the most effective intervention. Exercise interventions also showed positive effects on anxiety. Most studies were judged to have some concerns regarding their risk of bias, and the confidence in evidence was often very low according to CINeMA. CONCLUSION: For postmenopausal women, there is very low to moderate quality evidence that exercise interventions are an effective antidepressant therapy, with mind-body exercise most likely being the optimal type. TRIAL REGISTRATION: This meta-analysis was prospectively registered with PROSPERO (registration number: CRD42024505425).

A new mountain pitviper of the genus Ovophis Burger in Hoge & Romano-Hoge, 1981 (Serpentes, Viperidae) from Yunnan, China.

Based on a molecular phylogenetic analysis and morphological comparison, a new species of mountain pitviper, Ovophisjenkinsi sp. nov., is described. The new species was collected in Yingjiang County, Yunnan Province, China. It can be distinguished from congeneric species by the following characters: (1) internasals in contact or separated by one small scale; (2) second supralabial entire and bordering the loreal pit; (3) dorsal scales in 23 (25)-21 (23, 25)-19 (17, 21) rows; (4) 134-142 ventrals; (5) 40-52 pairs of subcaudals; (6) third supralabial larger than fourth in all examined specimens of Ovophisjenkinsi sp. nov.; (7) deep orange-brown or dark brownish-grey markings on dorsal head surface; (8) background color of dorsal surface deep orange-brown or dark brownish-grey; (9) both sides of dorsum display dark brown trapezoidal patches; (10) scattered small white spots on dorsal surface of tail.

Effects of exercise interventions on quality of life in patients with breast cancer: A systematic review and network meta-analysis.

OBJECTIVE: To compare and rank the effectiveness of four primary categories of exercise modalities (aerobic, resistance, mind-body, and combined exercise [CE]) in improving the Quality of life (QoL) of women with breast cancer in a network meta-analysis (NMA). METHODS: Articles published in English and indexed in the PubMed (MEDLINE), EBSCO, Web of Science, SPORTDiscus, The Cochrane Library, Google Scholar, PsycINFO, EMBASE, and CINAHL Plus databases were identified from inception to 12 October 2023. Studies that met the eligibility criteria were assessed for risk of bias. A frequentist NMA was conducted to appraise the efficacy of different exercise types. RESULTS: This study included 56 studies with 3904 participants. Aerobic, mind-body, and combined exercises effectively improved QoL compared to controls. The surface under the cumulative ranking curve (SUCRA) indicated that CE best improved patients' QoL (SUCRA = 96.7%). Analysis of the secondary outcomes suggests that exercise reduced patients' depression (standardized mean difference [SMD] = -0.38, 95% confidence interval [CI] = -0.70 to -0.06, p < 0.001; I2 = 79%) and anxiety (SMD = -0.50, 95% CI = -0.69 to -0.31, p < 0.001; I2 = 27.4%) but did not affect self-esteem. CONCLUSION: All exercise types but resistance were effective in improving the QoL of women with breast cancer, CE (the combination of aerobic and resistance exercise) had the highest likelihood of being optimal for improving QoL.

The role of targeting glucose metabolism in chondrocytes in the pathogenesis and therapeutic mechanisms of osteoarthritis: a narrative review.

Osteoarthritis (OA) is a common degenerative joint disease that can affect almost any joint, mainly resulting in joint dysfunction and pain. Worldwide, OA affects more than 240 million people and is one of the leading causes of activity limitation in adults. However, the pathogenesis of OA remains elusive, resulting in the lack of well-established clinical treatment strategies. Recently, energy metabolism alterations have provided new insights into the pathogenesis of OA. Accumulating evidence indicates that glucose metabolism plays a key role in maintaining cartilage homeostasis. Disorders of glucose metabolism can lead to chondrocyte hypertrophy and extracellular matrix degradation, and promote the occurrence and development of OA. This article systematically summarizes the regulatory effects of different enzymes and factors related to glucose metabolism in OA, as well as the mechanism and potential of various substances in the treatment of OA by affecting glucose metabolism. This provides a theoretical basis for a better understanding of the mechanism of OA progression and the development of optimal prevention and treatment strategies.

Melatonin in cancer biology: pathways, derivatives, and the promise of targeted delivery.

Melatonin, historically recognized for its primary role in regulating circadian rhythms, has expanded its influence particularly due to its wide range of biological activities. It has firmly established itself in cancer research. To highlight its versatility, we delved into how melatonin interacts with key signaling pathways, such as the Wnt/ß-Catenin, PI3K, and NF-κB pathways, which play foundational roles in tumor development and progression. Notably, melatonin can intricately modulate these pathways, potentially affecting various cellular functions such as apoptosis, metastasis, and immunity. Additionally, a comprehensive review of current clinical studies provides a dual perspective. These studies confirm melatonin's potential in cancer management but also underscore its inherent limitations, particularly its limited bioavailability, which often relegates it to a supplementary role in treatments. Despite this limitation, there is an ongoing quest for innovative solutions and current advancements include the development of melatonin derivatives and cutting-edge delivery systems. By synthesizing the past, present, and future, this review provides a detailed overview of melatonin's evolving role in oncology, positioning it as a potential cornerstone in future cancer therapeutics.

[Circadian rhythm and health: dialogue between traditional Chinese medicine and modern medicine].

Circadian rhythm refers to the daily rhythmic variations in an organism. The irregular lifestyles of modern humans have led to a high incidence of chronic diseases, highlighting an inseparable relationship between disrupted circadian rhythm and disease development. TCM has long discussed rhythmic variations, with records dating back to the Yellow Emperor's Inner Canon(Huang Di Nei Jing), which laid a rich theoretical foundation for the research on circadian rhythm. Modern medical research has provided a more comprehensive explanation of its molecular mechanisms. This article integrated the current understanding of circadian rhythm in both Chinese and western medicine, emphasizing the crucial relationship between rhythm regulation and disease treatment. By highlighting the interdisciplinary nature of the two fields, it offers new directions for exploring the field of chronomedicine.

Quantification of the renal sinus fat and exploration of its relationship with ectopic fat deposition in normal subjects using MRI fat fraction mapping.

Purpose: To determine the renal sinus fat (RSF) volume and fat fraction (FF) in normal Chinese subjects using MRI fat fraction mapping and to explore their associations with age, gender, body mass index (BMI) and ectopic fat deposition. Methods: A total of 126 subjects were included in the analysis. RSF volume and FF, visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) area, and hepatic and pancreatic FFs were measured for each subject. The comparisons in gender were determined using two-tailed t-tests or the nonparametric Mann-Whitney U-test for normally or non-normally distributed data for continuous variables and the chi-square test for categorical variables. Comparisons of RFS volume and FF between right and left kidneys were determined using paired sample t-tests. Multivariable logistic models were performed to confirm whether RSF differences between men and women are independent of VAT or SAT area. When parameters were normally distributed, the Pearson correlation coefficient was used; otherwise, the Spearman correlation coefficient was applied. Results: The RSF volumes (cm3) of both kidneys in men (26.86 ± 8.81 for right and 31.62 ± 10.32 for left kidneys) were significantly bigger than those of women (21.47 ± 6.90 for right and 26.03 ± 8.55 for left kidneys) (P < 0.05). The RSF FFs (%) of both kidneys in men (28.33 ± 6.73 for right and 31.21 ± 6.29 for left kidneys) were significantly higher than those of the women (23.82 ± 7.74 for right and 27.92 ± 8.15 for left kidneys) (P < 0.05). The RSF differences between men and women are independent of SAT area and dependent of VAT area (except for right RSF volume). In addition, the RSF volumes and FFs in both kidneys in the overall subjects show significant correlations with age, BMI, VAT area, hepatic fat fraction and pancreatic fat fraction (P < 0.05). However, the patterns of these correlations varied by gender. The RSF volume and FF of left kidney were significantly larger than those of the right kidney (P < 0.05). Conclusion: The association between renal sinus fat and ectopic fat deposition explored in this study may help establish a consensus on the normal values of RSF volume and FF for the Chinese population. This will facilitate the identification of clinicopathological changes and aid in the investigation of whether RSF volume and FF can serve as early biomarkers for metabolic diseases and renal dysfunction in future studies.

Molecular mechanisms of COVID-19-induced pulmonary fibrosis and epithelial-mesenchymal transition.

As the outbreak of COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) first broke out in Hubei Province, China, at the end of 2019. It has brought great challenges and harms to global public health. SARS-CoV-2 mainly affects the lungs and is mainly manifested as pulmonary disease. However, one of the biggest crises arises from the emergence of COVID-19-induced fibrosis. At present, there are still many questions about how COVID-19 induced pulmonary fibrosis (PF) occurs and how to treat and regulate its long-term effects. In addition, as an important process of fibrosis, the effect of COVID-19 on epithelial-mesenchymal transition (EMT) may be an important factor driving PF. This review summarizes the main pathogenesis and treatment mechanisms of COVID-19 related to PF. Starting with the basic mechanisms of PF, such as EMT, transforming growth factor-ß (TGF-ß), fibroblasts and myofibroblasts, inflammation, macrophages, innate lymphoid cells, matrix metalloproteinases and tissue inhibitors of metalloproteinases, hedgehog pathway as well as Notch signaling. Further, we highlight the importance of COVID-19-induced EMT in the process of PF and provide an overview of the related molecular mechanisms, which will facilitate future research to propose new clinical therapeutic solutions for the treatment of COVID-19-induced PF.

[Hydrochemical Characteristics and Controlling Factors of Groundwater in the Leizhou Peninsula].

Groundwater resources in the Leizhou Peninsula provide a strong support for the economic and social development. Therefore, understanding the chemical characteristics and formation mechanism of groundwater in this area is necessary for the rational exploitation and sustainable utilization of water resources. In this study, 43 groundwater samples were collected, and the hydrochemical characteristics and controlling factors were analyzed by descriptive statistical analysis, Piper triangular diagrams, ArcGIS spatial interpolation, Gibbs diagram, and ion ratios. The results showed that:① The anions and cations of the groundwater in the study area were mainly HCO3-, Ca2+, and Na+, and the hydrochemical types were mainly HCO3-Cl-Na-Ca, HCO3-Cl-Na-Ca-Mg, HCO3-Cl-Na-Mg, and HCO3-Na. The contents of Cl-, SO42-, and Na+were higher in the west of Leizhou City compared to other areas. The sites with higher contents of HCO3-, NO3-, Ca2+, Mg2+, and K+ were mainly concentrated in the southwest and eastern coastal areas. ② The chemical evolution of groundwater was mainly affected by water-rock interaction, cation alternating adsorption, and anthropogenic activities. The sources of Na+ and K+ were mainly from evaporative and silicate rocks, Ca2+ and Mg2+ were mainly from carbonate karstification, while NO3- originated from anthropogenic activities.

[Source Analysis and Health Risk Assessment of Heavy Metals in Groundwater of Leizhou Peninsula].

Source identification and health risk assessment of heavy metals in groundwater is one of the key issues in China's new era of environmental management. In order to reveal the status, sources, and health risk of pollutants in groundwater of the Leizhou Peninsula, 44 groundwater samples were collected, and the concentrations and spatial distribution of Cr, Mn, Cu, Zn, As, Cd, Hg, and Pb were measured and analyzed. The sources of heavy metals in groundwater were then determined through correlation coefficient and principal component analysis. Finally, the health risk model was used to evaluate the different health risks associated with these heavy metals. The results showed that the average value of heavy metal elements in groundwater of the Leizhou Peninsula does not inferior to the class Ⅱ water quality standard(GB/T 14848-2017). However, As, Mn, and Cd do not meet the standard. The overall spatial distribution indicated obvious spatial differences, with higher values in the south than in the north. Heavy metal sources can be identified as three principal components (PCs). PC1 (Cu, Zn, Cd, and Pb) metals mainly originate from industrial, agricultural, and traffic sources. PC2 (Cr, Mn, and As) sources can be both natural and man-made, and PC3 (Hg) sources are primarily man-made. For the groundwater of the Leizhou Peninsula, the health risks of 8 metals are with the acceptable range, the carcinogenic risk of adults is higher than that of children, and the risk of drinking exposure is higher than that of skin exposure. The study shows that the environmental protection department should encourage the rational exploitation of groundwater resources and control the sources of pollution to reduce health risks.

A sheep in wolf's clothing: Elaphe xiphodonta sp. nov. (Squamata, Colubridae) and its possible mimicry to Protobothrops jerdonii.

Based on combined morphological and osteological characters and molecular phylogenetics, we describe a new species of the genus Elaphe that was discovered from the south slope of the Qinling Mountains, Shaanxi, China, namely Elaphe xiphodonta sp. nov. It is distinguished from the other congeners by a combination of the following characters: dorsal scales in 21-21-17 rows, the medial 11 rows keeled; 202-204 ventral scales, 67-68 subcaudals; two preoculars (including one subpreocular); two postoculars; two anterior temporals, three posterior temporals; reduced numbers of maxillary teeth (9+2) and dentary teeth (12); sharp cutting edges on the posterior or posterolateral surface of the rear maxillary teeth and dentary teeth; dorsal head yellow, three distinct markings on the head and neck; a distinct black labial spot present in supralabials; dorsum yellow, 46-49 complete (or incomplete) large black-edged reddish brown blotches on the body and 12-19 on the tail, two rows of smaller blotches on each ventrolateral side; ventral scales yellow with mottled irregular black blotches, a few irregular small red spots dispersed on the middle of the ventral. Based on molecular phylogenetic analyses, the new species forms the sister taxon to E. zoigeensis. The discovery of this new species increases the number of the recognized species in the genus Elaphe to 17.

Phylogeographic study of the Bufo gargarizans species complex, with emphasis on Northeast Asia.

We conduct a phylogeographic and population genetic study of the Asiatic toad (Bufo gargarizans) to understand its evolutionary history, and the influence of geology and climate. A total of 292 individuals from 94 locations were genotyped for two mitochondrial loci (cytb, ND2) and five nuclear introns (Sox9-2, Rho-3, CCNB2-3, UCH-2, and DBI-2), and we performed a suite of phylogenetic, population genetic, and divergence dating analyses. The phylogenetic trees constructed using mitochondrial loci inferred B. gargarizans being divided into two major groups: China mainland and Northeast Asia (Northeast China, Russia, and Korean Peninsula). As with previous studies of this species, we recover population genetic structure not tied to geographic region. Additionally, we discover a new genetic clade restricted to Northeast Asia that points towards the Korean Peninsula being a glacial refugium during the Pleistocene. The weak phylogeographic pattern of B. gargarizans is likely the result of multiple biological, anthropogenic, and historical factors - robust dispersal abilities as a consequence of physiological adaptations, human translocation, geologic activity, and glacial cycles of the Pleistocene. We highlight the complex geologic and climatic history of Northeast Asia and encourage further research to understand its impact on the biodiversity in the region.

A definition of the Goniurosaurus yingdeensis group (Squamata, Eublepharidae) with the description of a new species.

A definition of the Goniurosaurus yingdeensis group is presented in this study, on the basis of morphological and phylogenetic analyses based on a series of additional specimens. Moreover, a new species of this group, Goniurosaurus varius sp. nov., is proposed for northern Guangdong Province, China. The new species can be distinguished from the other two congeners of this group by the following unique characters: one or two internasals; enlarged supraorbital tubercles absent; paravertebral tubercles between limb insertions 27-29; dorsal tubercle rows at midbody 21-24; ten precloacal pores in males and absent in females; body bands with black spots; iris orange-red.

A new species of the Rana japonica group (Anura, Ranidae, Rana) from China, with a taxonomic proposal for the R. johnsi group.

Rana jiulingensis sp. nov., a new species from Hunan and Jiangxi, southeastern China, is described. The new species is assigned to the R. japonica group. The clade comprising R. jiulingensis sp. nov. and R. dabieshanensis from Anhui is the sister taxon of R. omeimontis from Sichuan. Rana jiulingensis sp. nov. can be distinguished by the significant divergences in the 16S and COI genes, and the combination of following morphological characters: body size medium, SVL 48.3-57.8 mm in adult males and 48.2-57.5 mm in adult females; dorsolateral fold straight; digits without circummarginal grooves; dorsal skin smooth; tibio-tarsal articulation reaching forward beyond the tip of snout; heels overlapping; webbing formula of toes: I 1⅓ - 2 II 1⅓ - 2⅓ III 1½ - 2⅔ IV 3 - 1⅓ V; absence of vocal sacs in males; and presence of creamy white nuptial pad with tiny hoar spines on the finger I and reddish tubercles on loreal and temporal regions in breeding males. Furthermore, based on our results and the previous literature, R. zhengi is synonymized with R. sangzhiensis, and a new species group, the Rana johnsi group, is proposed for the R. johnsi and R. sangzhiensis. Currently, the Rana contains 41 recognized species, and the phylogenetic placements of several species remain unresolved.

Comprehensive approaches reveal three cryptic species of genus Nidirana (Anura, Ranidae) from China.

Three cryptic species, which were previously reported as Nidirana adenopleura, are revealed on the basis of comprehensive approaches. Nidirana guangdongensis Lyu, Wan, and YY Wang, sp. nov. is distributed in Nanling Mountains and southern Luoxiao Mountains, Nidirana mangveni Lyu, Qi, and YY Wang, sp. nov. is known from northern Zhejiang, and Nidirana xiangica Lyu and YY Wang, sp. nov. occurs in Xiangjiang River Basin, while the true Nidirana adenopleura is designated from Taiwan Island, northern Fujian, southern Zhejiang, and central Jiangxi. These three new species can be distinguished from all congeners by significant divergences in the mitochondrial 16S and CO1 genes, differences in advertisement calls, and the combination of multiple characteristics. This work indicates that the current records of Nidirana adenopleura should be of a species complex composed of multiple species and have clarified the true identity of N. adenopleura.

Diversity and phylogeography of Northeast Asian brown frogs allied to Rana dybowskii (Anura, Ranidae).

We investigated the species diversity and phylogeography of the Northeast Asian brown frogs allied to Rana dybowskii (the R. dybowskii species complex: R. dybowskii, R. pirica, and R. uenoi) using four mitochondrial and three nuclear loci. Phylogenetic analyses confirmed the existence of three distinct species in this complex; using extensive molecular data, we confirm the validity of Rana uenoi recognized as a distinct species, and infer R. dybowskii and R. pirica to be sister species. Also, we included populations from previously unsampled regions in Northeast China, and identified them to be R. dybowskii. While many species in Northeast Asia diverged due to Pleistocene glaciation, divergence-dating analyses inferred older, Miocene speciation in the R. dybowskii species complex. Ancestral area reconstruction identified the orogenic movement of the Changbai Mountain Range and the opening of the Sea of Japan/East Sea being major events influencing allopatric speciation.

A new species of the genus Scutiger (Anura: Megophryidae) from Medog of southeastern Tibet, China.

A new species of Scutiger Theobald, 1868 is described from Medog, southeastern Tibet, China, based on morphological and molecular data. The new species was previously identified as Scutiger nyingchiensis, but it can be differentiated from the latter and all other congeners by the following combination of characters: (1) medium adult body size, SVL 50.5-55.6 mm in males and 53.8-57.2 mm in females; (2) maxillary teeth absent; (3) web rudimentary between toes; (4) prominent, conical-shaped tubercles on dorsal and lateral surfaces of body and limbs; (5) tubercles covered by black spines in both sexes in breeding condition; (6) a pair of pectoral glands and a pair of axillary glands present and covered by black spines in males in breeding condition, width of axillary gland less than 50% of pectoral gland; (7) nuptial spines present on dorsal surface of first and second fingers, and inner side of third finger in males in breeding condition; (8) spines absent on the abdominal region; (9) vocal sac absent. In addition, the distribution and conservation status of the new species are also discussed.

Influence of geology and human activity on the genetic structure and demography of the Oriental fire-bellied toad (Bombina orientalis).

The Oriental fire-bellied toad (Bombina orientalis) is a commonly used study organism, but knowledge of its evolutionary history is incomplete. We analyze sequence data from four genetic markers (mtDNA genes encoding cytochrome c oxidase subunit I, cytochrome b, and 12S-16S rRNA; nuDNA gene encoding recombination activating gene 2) from 188 individuals across its range in Northeast Asia to elucidate phylogeographic patterns and to identify the historic events that shaped its evolutionary history. Although morphologically similar across its range, B. orientalis exhibits phylogeographic structure, which we infer was shaped by geologic, climatic, and anthropogenic events. Phylogenetic and divergence-dating analyses recover four genetically distinct groups of B. orientalis: Lineage 1-Shandong Province and Beijing (China); Lineage 2-Bukhan Mountain (Korea); Lineage 3-Russia, Northeast China, and northern South Korea; and Lineage 4-South Korea. Lineage 2 was previously unknown. Additionally, we discover an area of secondary contact on the Korean Peninsula, and infer a single dispersal event as the origin of the insular Jeju population. Skyline plots estimate different population histories for the four lineages: Lineages 1 and 2 experienced population decreases, Lineage 3 remained stable, while Lineage 4 experienced a sharp increase during the Holocene. The timing of the population expansion of Lineage 4 coincides with the advent of rice cultivation, which may have facilitated the increase in population size by providing additional breeding habitat.

Implications of flexible-shelled eggs in a Cretaceous choristoderan reptile.

Flexible, or soft-shelled, eggs are almost unknown in the fossil record, leaving large gaps in our knowledge of the reproductive biology of many tetrapod clades. Here, we report two flexible-shelled eggs of the hyphalosaurid choristodere Hyphalosaurus baitaigouensis from the Early Cretaceous of China, one containing an embryo and the second associated with a neonate. Choristoderes are an enigmatic group of aquatic reptiles that survived the K-T extinction but died out in the Miocene. Hyphalosaurids, a specialized clade of Choristodera, resemble miniature plesiosaurs and are considered to be primarily aquatic in habit. Scanning electron microscopy of samples from the eggs reveals a thin, non-columnar external mineralized layer characterized by rounded nodes and tentatively identified poorly structured irregular pores, with an underlying amorphous layer presumably representing decomposed protein fibrils. While the relationships of Choristodera remain controversial, eggshell microstructure more closely resembles that of Lepidosauromorpha (the lineage including lizards) as opposed to that of Archosauromorpha (the lineage including birds and crocodiles).