Ontogenetic Feature Research Articles

Weight and linear growth of the skeleton of domestic reindeer of the Nenets breed

Reindeer are one of the most widespread and adapted representatives of the northern territories of the Arctic zone of the Russian Federation. Features of skeletal development are an important ontogenetic feature that reflects the level of development of the animal and the degree of realization of its genetic resource in the phenotype. The purpose of the presented research is to study the characteristics of the growth and development of the skeleton of the Nenets reindeer breed, taking into account the sex and age of the animals. Data were obtained on the peripheral and axial growth of skeletal bones from birth to the end of growth of males and females. Based on the studies conducted, it was possible to establish that in the postnatal period, the axial part of the skeleton of male and female reindeer grows faster than the peripheral part. Linear bone growth in deer ends earlier than weight growth. Females, compared to males, are characterized by more intense weight and linear growth of the skeleton, which confirms the relatively earlier completion of the growth and development of the body of females in relation to males of the same age. The growth rate of the reindeer skeleton is inferior to the rate of increase in live weight, which increases mainly due to the active growth of other tissues and organs. The greatest increase in skeletal mass and linear growth is observed during the milk period. Consequently, the first six months of a reindeer’s life are of great importance for the formation of physique, physiological precocity and the level of future meat and labor productivity. The revealed patterns of skeletal growth for reindeer of the Nenets breed do not exclude the possibility of extending them to reindeer of other breeds.

A new wing skeleton of the Jehol tapejarid Sinopterus and its implications for ontogeny and paleoecology of the Tapejaridae

The tapejarid pterosaurs flourished in the Jehol Biota with an abundance of immature individuals and a rarity of individuals at skeletal maturity. Most of these individuals plot well on an ontogenetic series based on the proportions of limb elements, but this has lacked histological evidence until now. Here, a new wing skeleton of Sinopterus was thin-sectioned to provide the first histological data about the ontogeny of the Jehol tapejarids. Histologically, the new specimen is an immature individual at a late juvenile stage prior to sexual maturity. It is grouped with medium-sized and medium-crested individuals, which are distinct from the small-sized and crestless individuals as well as the rare large-sized and large-crested individuals at skeletal maturity, supporting the presence of the premaxillary crest as an ontogenetic feature in the Jehol tapejarids. Furthermore, this histology indicates that the largest skeletally immature individuals might have reached the sexual maturity. Enigmatically, there is a size gap between sexual and skeletal maturity, which is at about 79% of the large size, implying a ontogenetic strategy comparable with Pteranodon and possibly with the Brazilian tapejarid Caiuajara. This size gap is consistent with lack of the larger sexually mature individuals in the Jehol Biota, which is hypothesized to be a migratory habitat for the Jehol tapejarids.

A baurusuchid yearling (Mesoeucrocodylia, Crocodyliformes), from the Adamantina Formation, Bauru Group, Upper Cretaceous of Brazil

ABSTRACT Occurrences of young and immature individuals, relatively rare in the fossil record, are important due to the great amount of morphological and evolutionary information they reveal about a lineage’s development. Although crocodylomorphs are the most abundant terrestrial vertebrates found in the Bauru Basin, southeastern Brazil, even outnumbering dinosaurian materials, much remains to be understood about their anatomy, ecology, and ontogeny. Egg fragments, nests and nesting sites attributed to Baurusuchus have been previously described, but unfortunately none of these yielded embryonic or hatchling remains. Here, we describe, for the first time, skeletal material of a small notosuchian yearling, recovered from the Adamantina Formation, with osteological features consistent with a baurusuchid affinity. We provide and discuss osteological and histological evidence of its ontogenetic stage, revealing morphological characters distinct from most adult forms, including conspicuous centro-parapophyseal laminae and developed ventral keels. Computerised tomography data also allowed for the identification of incipient ossification and a novel ontogenetic feature in the diminishing volume of the frontal´s internal recesses. Similar materials will increase our understanding of notosuchian ontogeny and diversity, thus requiring growth characters to be integrated into future phylogenies.

Cranial ornamentation of a large Brachydectes newberryi (Recumbirostra: Lysorophia) from Linton, Ohio.

Although the cranial anatomy of the lysorophian tetrapod Brachydectes has been reported in detail recently, many attributes of the group are inadequately known, and lysorophian systematics remain unclear. One under-described aspect of the genus is the development and variation of cranial ornamentation. Whereas the smallest skulls (< 5 mm in length) lack sculpturing, ornamentation increases in progressively larger specimens and is conspicuous in the largest (> 30 mm skull length) individuals. It includes rugose ornament on the anterior cranial roof elements (frontals and anterior parietals) and pustular ornament on the posterior elements (posterior parietals and postparietals). Such ornamentation is unique within recumbirostrans and is identified as an ontogenetic feature.

Morphology, morphogenesis, and phylogeny of an Anteholosticha intermedia (Ciliophora, Urostylida) population from the United States

A distinct population of Anteholosticha intermedia was isolated from soil in the Great Smoky Mountains of North Carolina, USA, and its morphology, morphogenesis and molecular phylogeny investigated by microscopic observations of live and protargol-prepared specimens and analyses of the sequence of small subunit (SSU) rDNA. Our population closely resembles the populations from Austria and Korea. Members of the genus Anteholosticha have been regarded as ontogenetically diverse, which is confirmed by the present work. The most noteworthy ontogenetic feature of the American population of A. intermedia is that the oral primordium in the proter appears apokinetally at the posterior end of the undulating membranes anlage at the beginning of division and then dedifferentiates midway through morphogenesis. Molecular phylogenetic analyses demonstrate, with high support, that the American population of A. intermedia is clearly distinct from congeners and branches as part of a sister lineage to the Bakuella–Urostyla clade that belongs to the major clade comprising the order Urostylida.

Ontogenetic variability in old and new collections of Dicranophyllum gallicum Grand'Eury from the late Palaeozoic of Europe.

Dicranophyllum gallicum Grand’Eury is described by means of a morphometric analysis of eighty two samples from various old and new localities in western and central Europe. Stem, leaf cushions, leaf scars, leaves, axillary structures and potential seeds are described in detail, and discussed in comparison to earlier studies. The encountered variability in size and structure is shown to be higher than what was described earlier. The organisation of the leaf cushion and scar density vary gradually with the stem width, while stratigraphic position and ecology do not relate to it. It is concluded that the described variability represents an ontogenetic feature rather than a phylogenetic or ecologic one. The juvenile plants are characterised by small stems, a high leaf scar density and elongated leaf cushions with a dominant apical field, while mature specimens are characterized by a wide stem, a relatively low leaf scar density and relatively wide leaf cushions with a pronounced basal field. Axillary shoots and potential seeds of D. gallicum are described and illustrated in detail for the first time. A reconstruction based on the studied material is presented.

Morphology and ontogenesis of Stylonychia (Metastylonychia) nodulinucleata nov. subgen. (Ciliophora, Hypotricha) from Australia

Using standard methods, we describe the morphology and ontogenesis of a possibly very rare ciliate, Stylonychia (Metastylonychia) nodulinucleata nov. subgen (basionym: Stylonychia nodulinucleataShi and Li, 1993), isolated from soil of the Murray River floodplain in Australia. Further, we provide an English translation of the Chinese original description. Whether the Australian population is conspecific with the Chinese Stylonychia nodulinucleata requires a careful redescription of the latter. The new subgenus is characterized by a moniliform macronuclear strand and an ontogenetic feature, viz., that all cirri remain intact during anlagen formation. The moniliform macronuclear strand and the curved dorsal kineties resemble the stylonychid genus Coniculostomum. The species is easily recognized by the large size of the body and oral apparatus, the moniliform macronucleus, and the enormous caudal cirri reaching half of body length. Very likely, Stylonychia (Metastylonychia) nodulinucleata has a restricted distribution.

Morphology and molecular phylogeny of an Indian population of Cyrtohymena citrina (Ciliophora, Hypotricha), including remarks on ontogenesis of Urosomoida-Notohymena-Cyrtohymena group

The oxytrichid ciliate Cyrtohymena citrina, isolated from a soil sample from India, is moderately flexible, measures about 105×35μm in life and possesses citrine cortical granules, mainly arranged around cirri and dorsal cilia. Morphology and ontogenesis was investigated using live observation and protargol impregnation, and 18S rDNA was sequenced. Ontogenesis of an Indian population of Urosomoida agilis was also investigated. All three genera included in the Urosomoida-Notohymena-Cyrtohymena group have long been characterized by the ontogenetic feature that “anlagen V and VI of proter originate de novo”. This ontogenetic feature has been considered as the sole synapomorphy and an important diagnostic feature of the group. Based on current observations on ontogenesis of C. citrina and U. agilis, and previous observations of C. shii, Notohymena saprai and N. australis, the aforesaid ontogenetic feature is no longer true for the group. Indian population of C. citrina clusters with C. muscorum, Paraurosomoida, Urosomoida, Notohymena and Paraurostyla, and is placed away from Oxytricha granulifera; all oxytrichids in the cluster show deviation(s) from any of the typical oxytrichid features like Oxytricha pattern undulating membrane, 18 frontoventral transverse cirri and fragmentation of dorsal kinety 3. Phylogenetic analyses supported non-monophyly of Cyrtohymena and other flexible-bodied oxytrichids.

Comparative study of floral development in Onobrychis melanotricha, Hedysarum varium and Alhagi persarum (Leguminosae: Papilionoideae: Hedysareae)

Floral initiation and development of Hedysarum varium, Onobrychis melanotricha and Alhagi persarum was studied using epi-illumination light-microscopy techniques. The studied species belong to the tribe Hedysareae of the inverted repeat loss clade (IRLC clade), which is characterized by missing the large inverted repeat in the chloroplast genome. The main aim of our study was to determine developmental bases for similarities and differences among the three taxa and to verify the position of Alhagi relative to other genera of the IRLC clade. According to our observations, bracteoles are missing in Onobrychis melanotricha, but are present in the other two species. All three species share unidirectional sepal initiation starting with a median abaxial sepal and bidirectional petal initiation. Stamen initiation is unidirectional in all except in the outer stamen whorl of Hedysarum varium, where it is bidirectional. An important ontogenetic feature in O. melanotricha is the existence of five common primordia, which give rise to petal and stamen primordia. Although in H. varium and O. melanotricha common primordia are observed at some stages in floral organ initiations, in Alhagi all organs are initiated separately. Moreover, overlap in time of floral organs initiation occurs in H. varium and O. melanotricha, but not in A. persarum. The carpel initiates concurrently with the petal primordia in all. It might be presumed that Alhagi is primitive in relation to the other studied Hedysareae taxa, due to the presence of bracteoles, the absence of common primordia, and the lack of overlap in time of different organ initiations.

Evolutionary stasis in Euphorbiaceae pollen: selection and constraints

Although much attention has been paid to the role of stabilizing selection, empirical analyses testing the role of developmental constraints in evolutionary stasis remain rare, particularly for plants. This topic is studied here with a focus on the evolution of a pollen ontogenetic feature, the last points of callose deposition (LPCD) pattern, involved in the determination of an adaptive morphological pollen character (aperture pattern). The LPCD pattern exhibits a low level of evolution in eudicots, as compared to the evolution observed in monocots. Stasis in this pattern might be explained by developmental constraints expressed during male meiosis (microsporogenesis) or by selective pressures expressed through the adaptive role of the aperture pattern. Here, we demonstrate that the LPCD pattern is conserved in Euphorbiaceae s.s. and that this conservatism is primarily due to selective pressures. A phylogenetic association was found between the putative removal of selective pressures on pollen morphology after the origin of inaperturate pollen, and the appearance of variation in microsporogenesis and in the resulting LPCD pattern, suggesting that stasis was due to these selective pressures. However, even in a neutral context, variation in microsporogenesis was biased. This should therefore favour the appearance of some developmental and morphological phenotypes rather than others.

Floral development in Astragalus caspicus Bieb. (Leguminosae: Papilionoideae: Galegeae)

Floral organogenesis and development of the bushy perennial legume Astragalus caspicus were studied using epi-illumination light microscopy techniques. Based on our observations, flowers are in axillary two-flowered racemes, initiate all 21 floral organs and show precocious appearance of zygomorphy. The order of floral organ initiation is unidirectional in whorls starting from the abaxial position of the flower with a high degree of overlap. Another important ontogenetic feature is the existence of two successive common primordial stages categorized as primary and secondary. The primary common primordia produce antesepalous stamens and secondary common primordia. In contrast, the five secondary common primordia subdivide into a petal and an antepetalous stamen primordia. Our findings on floral ontogeny of A. caspicus provide new evidence for the complex and variable floral initiation and development in legumes. The floral apex with strong overlapping initiation of different organs illustrates a paradox in which different capabilities must be presumed to exist simultaneously. Moreover, two extraordinary types of common primordia represent possibly an advanced evolutionary trend where time intervals between the initiations of different floral organs in Papilionoideae are shortened.

Bizarre tubercles on the vertebrae of Eocene fossil birds indicate an avian disease without modern counterpart

Remains of fossil birds with numerous bony tubercles on the cervical vertebrae are reported from the Middle Eocene of Messel in Germany and the Late Eocene of the Quercy fissure fillings in France. These structures, which are unknown from extant birds and other vertebrates, were previously described for an avian skeleton from Messel but considered a singular feature of this specimen. The new fossils are from a different species of uncertain phylogenetic affinities and show that tuberculated vertebrae have a wider taxonomic, temporal, and geographic distribution. In contrast to previous assumptions, they are no ontogenetic feature and arise from the vertebral surface. It is concluded that they are most likely of pathologic origin and the first record of a Paleogene avian disease. Their regular and symmetrical arrangement over most of the external vertebral surface indicates a systemic disorder caused by factors that do not affect extant birds, such as especially high-dosed phytohormones or extinct pathogens.

Cranial crest development in the Azhdarchoid pterosaur Tupuxuara, with a review of the genus and tapejarid monophyly

Abstract: A portion of pterosaur skull from the Romualdo Member of the Santana Formation (?Albian–?Turonian, Cretaceous) of north‐east Brazil provides new data on the morphology and ontogeny of azhdarchoid pterosaur cranial crests. The specimen consists of parts of the cranial bones posterodorsal to the nasoantorbital fenestra, including partial nasals, lacrimals, frontals and possibly the parietals. A posterodorsally directed premaxillary crest with a concave posterior border is located dorsal to the posterior border of the nasoantorbital fenestra. A well‐defined suture indicates overlapping, posterodorsally directed growth of the premaxilla over the skull roof, suggesting that the generation of the premaxillary crest is a late ontogenetic feature and thus probably related to sexual display. The systematics of Tupuxuara and its relationship to other azhdarchoids is reviewed and a cladistic analysis of the group is presented. Tupuxuara is found to be the sister‐taxon to Azhdarchidae. Tupuxuara longicristatus Kellner and Campos, 1988 is argued to be the only valid named species in this genus and Thalassodromeus Kellner and Campos, 2002 is considered a junior subjective synonym of this taxon. As originally conceived, Tapejaridae is paraphyletic: a new, more restrictive version of Tapejaridae (including Tapejara and Sinopterus dongi) might exist, but its monophyly is weakly supported. Furthermore, Tapejara was found to be paraphyletic in all trees.

The decline of cross-species intersensory perception in human infants.

Between 6 and 10 months of age, infants become better at discriminating among native voices and human faces and worse at discriminating among nonnative voices and other species' faces. We tested whether these unisensory perceptual narrowing effects reflect a general ontogenetic feature of perceptual systems by testing across sensory modalities. We showed pairs of monkey faces producing two different vocalizations to 4-, 6-, 8-, and 10-month-old infants and asked whether they would prefer to look at the corresponding face when they heard one of the two vocalizations. Only the two youngest groups exhibited intersensory matching, indicating that perceptual narrowing is pan-sensory and a fundamental feature of perceptual development.

Multiple spontaneous rhythmic activity patterns generated by the embryonic mouse spinal cord occur within a specific developmental time window.

Spontaneous rhythmic activity is a ubiquitous phenomenon in developing neural networks and is assumed to play an important role in the elaboration of mature circuitry. Here we describe the day-by-day evolution of spontaneous activity in the embryonic mouse spinal cord and show that, at a specific developmental stage, 2 distinct rhythms coexist. On embryonic days E12.5 and E13.5, we observed a single type of regularly recurring short spike-episodes synchronized across cervical, thoracic, and lumbar levels. By E14.5, in addition to this motor rhythm, another type of spontaneous synchronous activity appeared, characterized by much longer lasting episodes separated by longer time intervals. On E15.5, these long episodes disappeared. Short episodes were less numerous and more irregular except at the cervical level where a rhythm was occasionally observed. By E16.5, this cervical rhythm became more robust, whereas the lumbar level fell almost silent. Surprisingly, at E17.5, spontaneous activity resumed at caudal levels, now characterized by numerous erratic short episodes. A striking ontogenetic feature of spontaneous activity was the occurrence of long episodes only at E14.5. Although concomitant at all levels of the spinal cord, long episodes displayed different patterns along the spinal cord, with tonic firing at the thoracic level and rhythmic discharge with occasional sequences of left/right alternation at the lumbar level. Thus at E14.5, the originally synchronized network has started to segregate into more specialized subnetworks. In conclusion, this work suggests that ongoing spontaneous rhythms do not follow a smooth evolution during maturation, but rather undergo profound changes at very specific stages.

Morphology and ontogenesis of Lambornella trichoglossa nov. spec., a new tetrahymenid ciliate (Protozoa, Ciliophora) from Brasilian tank bromeliads (Bromeliaceae)

This is the second of a series of papers describing the morphology and ontogenesis of new ciliates occurring in the cisterns of tank bromeliads, a group of rosette plants of tropical America, entrapping rainwater between the coalescing leaf axils. The new species described here was discovered in the tanks of ground bromeliads from the east coast (Mata Atlantica) of Brazil, South America, and in tank bromeliads of the Dominican Republic, Caribbean Sea. Its morphology and ontogenesis were investigated on cultivated specimens, using live observation, silver impregnation, and scanning electron microscopy. Morphologically, the new ciliate resembles the tetrahymenine genus Lambornella , while the habit is different in that it does not parasitize and produce cuticular cysts on mosquito larvae. Thus, it could be considered as representative of a new genus. Likewise, the Brazilian and Dominican populations are probably not conspecific. Basically, Lambornella trichoglossa nov. spec. has a tetrahymenid somatic and oral ciliary pattern with characteristics likely diagnostic for the, unfortunately, still insufficiently described type species of Lambornella , viz., an increased number (8) of postoral kineties, a spatulate preoral suture, a curved adoral membranelle 1, a sigmoidal membranelle 2, loop-like intrameridional silverlines, and a synchronous replacement of the parental oral apparatus during cell division, a conspicuous ontogenetic feature. Lambornella trichoglossa differs from the two described congeners mainly by the large size (200 × 50 m vs. 100 × 50 m), the fusiform to claviform shape (vs. ovoidal), the location of the contractile vacuole (near mid-body vs. posterior body third), a 25 m long caudal cilium (vs. lacking), and the arrangement of adoral membranelle 2 (directed to right vs. left). Considering that L. trichoglossa has not been found in Europe, though it is a large, conspicuous ciliate, it might be restricted to South America or Gondwana.

Development of the olfactory organ in the rainbow fish Nematocentris maccullochi (Atheriniformes, Melanotaeniidae).

The development of the olfactory organ in the rainbow fish, Nematocentris maccullochi, was studied using scanning and transmission electron microscopy; it was compared with the developmental process in other teleosts, especially in the closely related atherinids and cyprinodonts. The formation of the nares parallels that in atherinids, salmonids, cyprinids and heterosomats, but differs from that found in cyprinodonts. Another ontogenetic feature in which the olfactory organs of the rainbow fish and also of atherinids differ from those of cyprinodonts, is the occurrence of transitory kinociliary cells which disappear during the postlarval period. The divergent evolutionary pathways are discussed with reference to experimental investigations. During development, ciliated and microvillous receptor cell types occur. At the primary larval stage ciliated receptor neurons are exclusively present. At a later stage the microvillous type develops and becomes equal in frequency. Thus, the microvillous receptor represents a separate type of olfactory neuron and is not a progenitor of the ciliated receptor cell.

ASCOCARPIC CENTRUM ONTOGENY OF SPECIES OF HYPODERMATACEAE OF CONIFERS. II

Ascocarpic studies of the ontogeny of Lophodermium nitens disclosed a type of development unlike that of all other species of Hypodermataceae occurring on conifer needles. For this reason the centrum of L. nitens is designated as Type III and is compared with Type I (Gordon, 1966). Because L. nitens produces its ascocarp in several tissues of various species of pine, the ontogeny of ascocarps in different locations is discussed and illustrated. The most significant ontogenetic feature of the ascocarp of L. nitens is a layer of hyaline cells in the primordium; this layer is meristematic and gives rise to all subsequent structures of the centrum.