Juvenile Morphology Research Articles

The intertidal Fortuyniidae (Acari: Oribatida): new species, morphological diversity, ecology and biogeography.

Three new fortuyniid species, Fortuynia longiseta sp. nov., F. maledivensis sp. nov. and Alismobates pseudoreticulatus sp. nov., were found in littoral environments of the Maldives and Singapore and are described based on adult and juvenile morphology. A key is given to all Alismobates and Fortuynia species. The genus Fortuynia shows a homogeneous morphology and this is supposed to be a result of a limited habitat preference shown in this genus. Nearly all species only occur on rocky intertidal shores, except for F. rotunda dwelling in mangrove habitats and F. smiti found in riverine environments. Fortuynia smiti was now also found in a typical littoral habitat in Singapore and hence the remarkably broad ecological range of this species is discussed. The records of further fortuyniid species in the Indo-Pacific affirm that this taxon may be continuously distributed along shores of this geographic region.

Morphological variations within the ontogeny of Deinonychus antirrhopus (Theropoda, Dromaeosauridae).

This research resulted from the determination that MCZ 8791 is a specimen of Deinonychus antirrhopus between one and two years of age and that the morphological variations within particular growth stages of this taxon have yet to be described. The primary goal of the research is to identify ontogenetic variations in this taxon. Histological analyses determined that the Deinonychus specimens AMNH 3015 and MOR 1178 were adults. Comparisons are made between MCZ 8791 and these adult specimens. The holotype, YPM 5205, and the other associated specimens of this taxon within the YPM collection are similar in size and morphology to AMNH 3015. Further comparisons were made with the three partial specimens OMNH 50268, MCZ 4371, and MOR 1182. Although these specimens represent only a partial ontogenetic series, a number of morphological variations can be described. One secondary goal of this research is to compare the known pattern of variable, informative, ontogenetic characters in MCZ 8791 to a similar pattern of morphological characters in the sub-adult dromaeosaurid specimen Bambiraptor feinbergorum, AMNH FR: 30556. If the characters that have been determined to represent variable juvenile morphology in the ontogeny of Deinonychus are exhibited in Bambiraptor, this study will begin the process of determining whether a similar, conservative, ontogenetic pattern exists throughout the rest of Dromaeosauridae. If defensible, it may reduce the number of sympatric taxa within this clade. The other secondary goal relates to the forelimb function. The approximate body size, forelimb length, wrist development, and the presence of a more prominent olecranon on the ulna of MCZ 8791 support the hypothesis that juveniles of this taxon possessed some form of flight capability.

Morphometrics and molecular analysis of Ozolaimus linstowi n. sp. (Oxyuroidea: Pharyngodonidae) from the green lizard Iguana iguana.

Ozolaimus linstowi n. sp. is described from the large intestine of Iguana iguana Linnaeus, 1758 from Mexico. The present species can be easily distinguished from O. megatyphlon and O. cirratus by the presence of a long and slender pharynx not divided into sections, more similar to the remaining two species, O. monhystera and O. ctenosauri. Ozolaimus linstowi n. sp. can be differentiated from O. monhystera by the shorter spicule length and smaller body size of both males and females. Males of O. linstowi n. sp. are morphologically close to those of O. ctenosauri, but females possess a markedly smaller body size and differ in the organization of the oral cuticular armature. Adult males of O. linstowi n. sp. bear some characteristic features of the J3 juvenile morphology in terms of the cuticular organization of the oral and buccal capsule. Phylogenetic analysis of O. linstowi n. sp. using partial small subunit (SSU) and D2-D3 large subunit (LSU) rDNA shows relationships with several Oxyuridae genera.

Embryonic and Morphological Development of Larvae and Juvenile of the Buenos Aires Tetra, Hyphessobrycon anisitsi (Pisces Characidae) Characidae Fishes

ABSTRACTWe have launched an investigation for Embryonic Development, Larvae and Juvenile Morphology, of Buenos aires tetra in order to build basic data of Characidae and fish seeding production. We brought 50 couples of Characidae from Bizidduck aquarium in Yeosu-si, Jeollanamdo, from Korea on March of 2015. We put them in the tetragonal glass aquarium (50×50×30 cm). Breeding water temperature was 27.5~28.5°C (mean 28.0±0.05°C) and being maintained. The shape of fertilized egg was round shape, and it was adhesive demersal egg. The egg size was 0.63~0.91 mm (mean 0.74±0.07 mm, n=20). After getting fertilized egg, the developmental stage was gastrula stage, and embryo covered almost two-thirds of Yolk. Incubation was happened after 16 hours 13 minutes from gastrula stage, and the tail of juvenile came out first with tearing egg capsule. Immediately after the incubation, prelarvae had 3.78~3.88 mm length (mean 3.84±0.04 mm, n=5), and it had no mouth and anus yet. 34 days after hatching from the incubation, juvenile had 8.63~13.1 mm (mean 10.9±1.66 mm), and it had similar silver-colored body shape with its mother.

Embryonic and Morphological Development of Larvae and Juvenile of the Buenos Aires Tetra, Hyphessobrycon anisitsi (Pisces Characidae) Characidae Fishes.

We have launched an investigation for Embryonic Development, Larvae and Juvenile Morphology, of Buenos aires tetra in order to build basic data of Characidae and fish seeding production. We brought 50 couples of Characidae from Bizidduck aquarium in Yeosu-si, Jeollanamdo, from Korea on March of 2015. We put them in the tetragonal glass aquarium (50×50×30 cm). Breeding water temperature was 27.5~28.5°C (mean 28.0±0.05°C) and being maintained. The shape of fertilized egg was round shape, and it was adhesive demersal egg. The egg size was 0.63~0.91 mm (mean 0.74±0.07 mm, n=20). After getting fertilized egg, the developmental stage was gastrula stage, and embryo covered almost two-thirds of Yolk. Incubation was happened after 16 hours 13 minutes from gastrula stage, and the tail of juvenile came out first with tearing egg capsule. Immediately after the incubation, prelarvae had 3.78~3.88 mm length (mean 3.84±0.04 mm, n=5), and it had no mouth and anus yet. 34 days after hatching from the incubation, juvenile had 8.63~13.1 mm (mean 10.9±1.66 mm), and it had similar silver-colored body shape with its mother.

Description of postembrionic immature stages of Protomyobia onoi Jameson & Dusbabek, 1971 (Acariformes: Myobiidae) and comparative analysis of the juvenile external morphology in the tribe Protomyobiini

The external morphology of all immature postembrionic stages of Protomyobia onoi Jameson & Dusbabek, 1971 was described for the first time. The comparative analysis of the juvenile external morphology (tritonymphs or deutonymphs) belonging to the tribe Protomyobiini based on both original and literature data is provided. A total of 24 species belonging to 10 genera representing all three subtribes of Protomyobiini were analysed. Tritonymphs of the genus Protromyobia (Protomyobiina) are characterized by the losses of setae dTa, l′′1 and FG of legs I, l′ of femur-genu II and l′′ of femora-genua III and IV. Tritonymphs of the subtribe Afromyobiina are characterized by the absence of claws on legs I and seta l′1 on tibiae I and by the apically split eupathidia l′, l′′ of tarsi I. No synapomorphies of immature stages that characterized the whole subtribe Amorphacarina were found.

Spawning Behavior, Egg Development, Larvae and Juvenile Morphology of Hyphessobrycon eques (Pisces: Characidae) Characidae Fishes.

Hyphessobrycon eques is a famous fish for ornamental fish market and aquarium. They are inhabit in regions of Amazon and Paraguay River basin. Serpae fishs were investigated 2-3 males are chased to female, and then males attempted to simulate the females abdomen. After fertilization, eggs were kept in incubators at 28°C. The fertilized eggs had adhesive and demesal characteristics and had a mean diameter of 0.92 ± 0.01 mm. Larvae hatched at 16 hrs post fertilization. The hatched larvae averaged 2.90 ± 0.16 mm in total length (LT ). Complete yolk sac resorption and mouth opening occurred on the third day post hatching. At 45 days post hatching, the larvae were 12.5 ± 1.60 mm LT and had reached the juvenile stage.

Spawning Behavior, Egg Development, Larvae and Juvenile Morphology of Hyphessobrycon eques (Pisces: Characidae) Characidae Fishes

ABSTRACTHyphessobrycon eques is a famous fish for ornamental fish market and aquarium. They are inhabit in regions of Amazon and Paraguay River basin. Serpae fishs were investigated 2–3 males are chased to female, and then males attempted to simulate the females abdomen. After fertilization, eggs were kept in incubators at 28°C. The fertilized eggs had adhesive and demesal characteristics and had a mean diameter of 0.92 ± 0.01 mm. Larvae hatched at 16 hrs post fertilization. The hatched larvae averaged 2.90 ± 0.16 mm in total length (LT). Complete yolk sac resorption and mouth opening occurred on the third day post hatching. At 45 days post hatching, the larvae were 12.5 ± 1.60 mm LT and had reached the juvenile stage.

Maternal exposure to predator scents: offspring phenotypic adjustment and dispersal.

Predation is a strong selective pressure generating morphological, physiological and behavioural responses in organisms. As predation risk is often higher during juvenile stages, antipredator defences expressed early in life are paramount to survival. Maternal effects are an efficient pathway to produce such defences. We investigated whether maternal exposure to predator cues during gestation affected juvenile morphology, behaviour and dispersal in common lizards (Zootoca vivipara). We exposed 21 gravid females to saurophagous snake cues for one month while 21 females remained unexposed (i.e. control). We measured body size, preferred temperature and activity level for each neonate, and released them into semi-natural enclosures connected to corridors in order to measure dispersal. Offspring from exposed mothers grew longer tails, selected lower temperatures and dispersed thrice more than offspring from unexposed mothers. Because both tail autotomy and altered thermoregulatory behaviour are common antipredator tactics in lizards, these results suggest that mothers adjusted offspring phenotype to risky natal environments (tail length) or increased risk avoidance (dispersal). Although maternal effects can be passive consequences of maternal stress, our results strongly militate for them to be an adaptive antipredator response that may increase offspring survival prospects.

Egg Development and Morphology of Larva and Juvenile of the Oryzias latipes.

In order to monitor the developmental features of embryos, larvae, and juveniles of Oryzias latipes (Temminck and Schlegel), Oryzias latipes was caught in river of Shinduck-dong, Yeosu-si, Jeollanam-do, on May 2011, and experiments were carried out in Ichthyology laboratory at Chonnam National University. The blastodisc step was the first level for natural spawning. The optic vesicle, Kupffer's vesicle, myotome began to appear 75 hours 57 minutes later. After blastodisc development, the pectoral fins were made at 143 hours 37 minutes and the tail was separated started at the same time. Hatching was observed at 167 hours 27 minutes after blastodisc. The total length of the hatched larvae was 4.95~5.10 mm (mean, 5.01 mm), the mouth and anus were opened. Larvae used yolk completely after 3 days after hatching. The total length larvae was 5.45~5.56 mm (mean, 5.52 mm) after 8 days after hatching, and appeared the stems for tail. The stems pectoral, anal fin were showed after 14 days and the stems dorsal, ventral fin were appeared after 19 days. For 35 days after hatching, the total length of larvae 13.95~15.30 mm (mean, 14.64 mm), and at this time, fins and body were transferred like the adult Oryzias latipes.

Juvenile morphology in baleen whale phylogeny.

Phylogenetic reconstructions are sensitive to the influence of ontogeny on morphology. Here, we use foetal/neonatal specimens of known species of living baleen whales (Cetacea: Mysticeti) to show how juvenile morphology of extant species affects phylogenetic placement of the species. In one clade (sei whale, Balaenopteridae), the juvenile is distant from the usual phylogenetic position of adults, but in the other clade (pygmy right whale, Cetotheriidae), the juvenile is close to the adult. Different heterochronic processes at work in the studied species have different influences on juvenile morphology and on phylogenetic placement. This study helps to understand the relationship between evolutionary processes and phylogenetic patterns in baleen whale evolution and, more in general, between phylogeny and ontogeny; likewise, this study provides a proxy how to interpret the phylogeny when fossils that are immature individuals are included. Juvenile individuals in the peramorphic acceleration clades would produce misleading phylogenies, whereas juvenile individuals in the paedomorphic neoteny clades should still provide reliable phylogenetic signals.

First Report of the Pale Potato Cyst Nematode Globodera pallida from Bosnia and Herzegovina.

Potato cyst nematodes (PCN), the golden cyst nematode Globodera rostochiensis (Woll.) Bahrens, and the pale potato cyst nematode G. pallida (Stone) stand out by their remarkable and efficient parasitic adaptations causing high economic losses in potato production worldwide. They are A2 quarantine pests in EPPO countries as well as in Bosnia and Herzegovina. Up to now, only G. rostochiensis was reported from Bosnia and Herzegovina in 2011 (1). A systematic survey on the presence of PCN on entire territory of Bosnia and Herzegovina started in 2011. During the PCN survey, each year 120 soil samples of 1.5 liters were collected in the Republic of Srpska, one of the two entities of Bosnia and Herzegovina. The samples were collected by soil auger 10 cm in length with a diameter of 1.5 cm consisting of 100 cores. Entire samples were processed by Seinhorst elutriator (4). In autumn of 2012, PCN viable cysts were found in two soil samples originating from one field. From one sample, 12 cysts were extracted, and 2 from another sample. The morphology of cysts and second stage juveniles and molecular analysis established the identity of this species as pale cyst nematode G. pallida (3). In addition, the sequencing of the ribosomal DNA region revealed unequivocal similarity to G. pallida (GenBank Accession No. HF968449), while PCR-RFLP analysis (2) showed European type of G. pallida. The infested field is located in Rogatica, 70 km east of Sarajevo, which is one of the main seed and potato production areas in Bosnia and Herzegovina. The field history revealed that farm-propagated, farm-saved seed potatoes could spread the nematodes to other fields as well. Therefore, 26 additional samples were taken from the fields that belong to the infested field owner and the surrounding fields, but no cysts were found in additional samples. To determine infestation focus and its size, the infested field (1.1 ha) was divided into 46 plots (25 × 10 m) and resampled by taking samples of 60 cores per plot. The detailed sampling of the field revealed a high infestation of 1 cyst per gram of soil in the infestation focus. The high infestation level and the propagation of farm-own seed potatoes suggest that the introduction of G. pallida might have occurred several years ago, probably with imported seed potatoes. The infested field was subjected to the phytosanitary measure of banning potato production for a period of 6 years with the possibility of its prolongation, if cysts with live content are found afterward. It is expected that the nematode is present in other fields due to the farmer's practices of propagating farm-saved seed potatoes and deficient field machinery hygiene. Therefore, the whole area will be intensively monitored for the presence of PCN in the future. An adequate pest management plan will be prepared after PCN pathotype identification. To our knowledge, only one field was found infested with G. pallida during the 3-year PCN survey in Bosnia and Herzegovina. Strict phytosanitary measures for preventing further PCN introductions and spreading should be intensified.

Carryover effects of predation risk on postembryonic life-history stages in a freshwater shrimp

For organisms with complex life histories it is well known that risk experienced early in life, as embryos or larvae, may have effects throughout the life cycle. Although carryover effects have been well documented in invertebrates with different levels of parental care, there are few examples of predator-induced responses in externally brooded embryos. Here, we studied the effects of nonlethal predation risk throughout the embryonic development of newly spawned eggs carried by female shrimp on the timing of egg hatching, hatchling morphology, larval development and juvenile morphology. We also determined maternal body mass at the end of the embryonic period. Exposure to predation risk cues during embryonic development led to larger larvae which also had longer rostra but reached the juvenile stage sooner, at a smaller size and with shorter rostra. There was no difference in hatching timing, but changes in larval morphology and developmental timing showed that the embryos had perceived waterborne substances indicative of predation risk. In addition to carryover effects on larval and juvenile stages, predation threat provoked a decrease of body mass in mothers exposed to predator cues while brooding. Our results suggest that risk-exposed embryos were able to recognize the same infochemicals as their mothers, manifesting a response in the free-living larval stage. Thus, future studies assessing anti-predator phenotypes should include embryonic development, which seems to determine the morphology and developmental time of subsequent life-history stages according to perceived environmental conditions.

Development of the sea urchins Temnopleurus toreumaticus Leske, 1778 and Temnopleurus reevesii Gray, 1855 (Camarodonta: Temnopleuridae)

Sea urchin larvae near metamorphosis form an adult rudiment that is a complex of the juvenile structures. However, the details of the mechanisms that form the adult rudiment are unknown. The temnopleurid sea urchins Temnopleurus toreumaticus and Temnopleurus reevesii occur in Japan, but the development of their juvenile morphology has not been described. In this study, we observed their development by light and scanning electron microscopy to follow the adult rudiment formation and to consider the mechanisms of evolution of juvenile morphology in sea urchins. The prism embryos of both species formed two primary pore canals that elongated from the left and right coelomic sacs; the left canal connected the presumptive water vascular system to the hydropore. These organs were formed bilaterally and symmetrically in T. toreumaticus and with left-right asymmetry in T. reevesii. The right canal of both species had degenerated by the four-armed larval stage. At the prism stage, about six cells from the left oral ectoderm located between the left post-oral arm and the oral lobe formed a cell mass. The cell mass grew in diameter stepwise in T. toreumaticus by cell migration and by the formation of an epithelial pouch during the four- to six-armed larval stages and more rapidly in T. reevesii by the formation of a thin epithelium during the six-armed larval stage. In both species, the adult rudiment was formed by attachment of the cell mass to the hydrocoel. The larvae of T. toreumaticus metamorphosed from a tiny hole on the left ectoderm between the post-oral and postero-dorsal arms. These findings suggest that the developmental process involving the formation of two primary pore canals and a cell mass may have been acquired and conserved as common traits in the early development of indirect-developing temnopleurid species during evolutionary divergence from the Cidaroida.

Disparate Heterochronic Processes in Baleen Whale Evolution

Skulls of living baleen whales show distinctive patterns of heterochronic ontogenetic change with implications for mysticete evolution. Here, three baleen whale species are analysed and considered in a heterochronic context. Landmarks show that, during ontogeny, skull morphology changes significantly in the rorqual Balaenoptera borealis and humpback Megaptera novaeangliae (both Balaenopteridae), while the pygmy right whale Caperea marginata (Cetotheriidae: Neobalaeninae) retains an overall juvenile morphology from foetus to adult. Geometric morphometric analyses show that foetal and adult C. marginata are similar, whereas the balaenopterids are more disparate: foetal M. novaeangliae and B. borealis appear in one group, and adult M. novaeangliae and B. borealis are grouped closely. Heterochrony involves paedomorphosis for Caperea, and peramorphosis for the balaenopterids. Heterochrony might cause limited or released developmental constraints, leading to low taxonomic diversity in the single surviving species of neobalaenine, and higher diversity amongst balaenopterids.

External morphology of Oppiidae (Acari: Oribatida) in the light of the ontogeny of three species and genera

External morphology of juveniles and ontogeny of Oppia denticulata (R. & G. Canestrini, 1882), Multioppia laniseta Moritz, 1966 and Oppiella uliginosa (Willmann, 1919) are described and illustrated for the first time. The juveniles of these species are unpigmented and have a soft body, with smooth integument that is covered with microtuberculate cerotegument; they also have a similar number of setae on the prodorsum, gastronotum and in the anal, anogenital and epimeral regions. They differ mainly by the length of seta c2 in all juveniles, length of setae in and ex in the larva and seta le in the nymphs, and leg setation. The juveniles of Op. uliginosa have coupled seta d at some leg solenidia (σ on leg I, σ and φ on legs II and III, and φ on leg IV), whereas those of other species and the adults of all species lack this seta. The juveniles of O. denticulata and M. laniseta have sunken famulus ε on tarsus I, whereas those of Op. uliginosa and the adults of all species have it emergent. All instars of these species have setal pair p on tarsus I, and lack this pair of setae on leg tarsi II–IV. The adult Op. uliginosa has seta c2 on the notogaster, whereas other species lack it, but O. denticulata has an alveolus of this seta. The adult of M. laniseta has all setae of d-series, whereas those of other species lack them. Morphological characters of Oppia C.L. Koch, 1836; Multioppia Hammer, 1961; and Oppiella Jacot, 1937 are compared.

<p class="HeadingRunIn"><strong>A molecular phylogeny recovers <em>Strabomantis aramunha</em> Cassimiro, Verdade and Rodrigues, 2008 and <em>Haddadus binotatus</em> (Spix, 1824) (Anura: Terrarana) as sister taxa</strong></p>

The taxonomic and biogeographic affinities of Strabomantis aramunha from the Campos Rupestres of Brazil are intriguing. A unique skull morphology of females suggest affinities with the broad-headed eleutherodactylines of Northwestern South America in the genus Strabomantis. Male and juvenile morphology nonetheless suggest S. aramunha could be related to members of the recently described genus Haddadus from eastern Brazil. We assess the affinities of S. aramunha using molecular phylogenetic analyses of mitochondrial (12S, tRNAval, 16S, cyt b) and nuclear sequences (RAG-1and rhodopsin). Bayesian inference, likelihood, and parsimony analysis recover a highly supported clade with S. aramunha and H. binotatus as sister taxa. Accordingly, we transfer S. aramunha to Haddadus, and provide a new generic definition of the later. The distribution of species in Haddadus (highlands of the Espinhaço mountain Range and coastal eastern Brazil) is now concordant with the general pattern observed for other species in the area.

A molecular phylogeny recovers Strabomantis aramunha Cassimiro, Verdade and Rodrigues, 2008 and Haddadus binotatus (Spix, 1824) (Anura: Terrarana) as sister taxa.

The taxonomic and biogeographic affinities of Strabomantis aramunha from the Campos Rupestres of Brazil are intriguing. A unique skull morphology of females suggest affinities with the broad-headed eleutherodactylines of Northwestern South America in the genus Strabomantis. Male and juvenile morphology nonetheless suggest S. aramunha could be related to members of the recently described genus Haddadus from eastern Brazil. We assess the affinities of S. aramunha using molecular phylogenetic analyses of mitochondrial (12S, tRNAval, 16S, cyt b) and nuclear sequences (RAG-1and rhodopsin). Bayesian inference, likelihood, and parsimony analysis recover a highly supported clade with S. aramunha and H. binotatus as sister taxa. Accordingly, we transfer S. aramunha to Haddadus, and provide a new generic definition of the later. The distribution of species in Haddadus (highlands of the Espinhaço mountain Range and coastal eastern Brazil) is now concordant with the general pattern observed for other species in the area.

Histological assessments of intestinal immuno-morphology of tiger grouper juvenile, Epinephelus fuscoguttatus

Histological assessments on the intestinal morphology and immunity of tiger grouper juveniles, Epinephelus fuscoguttatus help in determining the earliest age to start an oral vaccination. This study describes the morphological development of the intestinal immunity of tiger grouper of various ages. Clinically healthy tiger groupers were selected and divided into 4 groups of 20 fish per group. Groups 1, 2, 3 and 4 consisted of juveniles of 30, 60, 90 and 120 days old, respectively. The whole intestine was collected and divided into three regions, the anterior, mid and posterior intestine and fixed in 10% buffered formalin before slides were prepared for microscopic examinations. It was found that the histological structures of the anterior intestine were for absorption of nutrient from digested food particles. The significantly (p < 0.05) higher number and length of the intestinal villi and smaller gap between villi were observed in the anterior intestine, which were structures for absorption. Structures of the posterior intestine were for immunity especially the adaptive immunity with included significantly (p < 0.05) higher numbers of the lymphoid and goblet cells, and significantly (p < 0.05) thicker lamina propria, which were structures for immunity. The mid intestine was the transition structure that involved in both absorption and innate immunity. The results also revealed that leukocytes existed in the lamina propria of 30-days old tiger groupers, an indication that the immune system was present at that particular age.Electronic supplementary materialThe online version of this article (doi:10.1186/2193-1801-2-611) contains supplementary material, which is available to authorized users.

First mandible and deciduous dentition of juvenile individuals of Sinomastodon (Proboscidea, Mammalia) from the Early Pleistocene Renzidong Cave of eastern China

Sinomastodon (Proboscidea, Mammalia) is a unique brevirostrine trilophodont gomphotheriid from Eurasia, which mainly occurs in China during the Plio-Pleistocene. Although much is known about adult individuals, the morphology of juveniles of this taxon is still poorly understood due to the scarcity of pertinent fossils. The present contribution represents the first detailed systematic study of the mandible and deciduous dentition of juvenile individuals of Sinomastodon jiangnanensis from the early Early Pleistocene (2.14–2.15 Ma) Renzidong Cave of eastern China. Based on morphological comparisons, the Renzidong juvenile mandible bears, on one hand, the transitional characteristics between the typical long-jawed trilophodont and elephantoid proboscideans, and, on the other hand, more primitive features than adult mandibles of Sinomastodon. This study of juvenile individuals of S. jiangnanensis provides new information to enhance the diagnosis of S. jiangnanensis, and confirms the validity of the species. It also provides evidence to show that the morphological transition of genus Sinomastodon from Neogene to Quaternary is mirrored in adult and juvenile individuals.