Morphology Gap Research Articles

A new tiny fossil penguin from the Late Oligocene of New Zealand and the morphofunctional transition of the penguin wing

ABSTRACT The Late Oligocene is a period of high penguin diversity, following major changes in the marine environment at the Eocene/Oligocene boundary and prior to the emergence of crown penguins in the Miocene. Historically, a large morphological gap existed between the most crownward Platydyptes among the Oligocene penguins from New Zealand and the Early Miocene stem penguins such as Palaeospheniscus from South America. Here we describe a new species that contributes to filling this gap. Pakudyptes hakataramea gen. et sp. nov. is the earliest tiny penguin, overlapping in size with the little penguin Eudyptula minor. Its distinctive combination of a well-developed proximal end of the humerus and an archaic elbow joint provides clues to the evolution of penguin wings. Phylogenetic analysis indicates that penguin wings evolved rapidly from the Late Oligocene to the Early Miocene, together with the acquisition of morphofunctional and hydrodynamical characteristics that enable the excellent swimming ability of modern penguins. As an indicator of aquatic adaptation, bone microanatomy shows a comparable structure to that of Eudyptula. The appearance of the smallest body size and the evolution of modern wings may have led to the ecological diversity of modern penguins, which confirms the importance of Zealandia in penguin evolution.

Cretaceous chloranthoids: early prominence, extinct diversity and missing links.

The Chloranthaceae comprise four extant genera (Hedyosmum, Ascarina, Chloranthus and Sarcandra), all with simple flowers. Molecular phylogenetics indicates that the Chloranthaceae diverged very early in angiosperm evolution, although how they are related to eudicots, magnoliids, monocots and Ceratophyllum is uncertain. Fossil pollen similar to that of Ascarina and Hedyosmum has long been recognized in the Early Cretaceous, but over the last four decades evidence of extinct Chloranthaceae based on other types of fossils has expanded dramatically and contributes significantly to understanding the evolution of the family. Studies of fossils from the Cretaceous, especially mesofossils of Early Cretaceous age from Portugal and eastern North America, recognized diverse flowers, fruits, seeds, staminate inflorescences and stamens of extinct chloranthoids. These early chloranthoids include forms related to extant Hedyosmum and also to the Ascarina, Chloranthus and Sarcandra clade. In the Late Cretaceous there are several occurrences of distinctive fossil androecia related to extant Chloranthus. The rich and still expanding Cretaceous record of Chloranthaceae contrasts with a very sparse Cenozoic record, emphasizing that the four extant genera are likely to be relictual, although speciation within the genera might have occurred in relatively recent times. In this study, we describe three new genera of Early Cretaceous chloranthoids and summarize current knowledge on the extinct diversity of the group. The evolutionary lineage that includes extant Chloranthaceae is diverse and abundantly represented in Early Cretaceous mesofossil floras that provide some of the earliest evidence of angiosperm reproductive structures. Extinct chloranthoids, some of which are clearly in the Chloranthaceae crown group, fill some of the morphological gaps that currently separate the extant genera, help to illuminate how some of the unusual features of extant Chloranthaceae evolved and suggest that Chloranthaceae are of disproportionate importance for a more refined understanding of ecology and phylogeny of early angiosperm diversification.

Nonconcatenative Morphology of MSA as Represented by Deverbal Verbs

The present paper considers how the derivation of deverbal verbs occurs in Arabic, a language with nonconcatenative morphology. As Arabic linguists have carefully investigated Arabic deverbal verbs, English literature lacks such investigations. Demonstrating how a word modifies meaning while explaining the intriguing nonconcatenative morphology of Arabic are reasons for considering deverbal verbs. To illustrate the hierarchical structure of Arabic deverbal verbs efficiently, autosegmental analysis was used. Arabic manuscripts and Modern Standard Arabic (MSA) dictionaries, using the Alshamela search engine and the Almaany search engine, were consulted to create a list of deverbal verbs. The manuscripts were utilized to find the initial lists, while the dictionaries were used to filter the list to only include the current deverbal verbs. The author found MSA deverbal verbs are derived through nonconcatenative morphology. The meanings of deverbal verb particles were concluded to belong to an additional autosegmental tier that is distinct from the tier of the root meaning. Notice how the meaning of the deverbal verb تضرّب [taDar:aba] ‘hit oneself’ as an intransitive verb retains the root meaning of ضرب [Daraba] ‘hit’ and adds the deverbal meaning indicating the action happening to oneself. It had been expected that all the verb roots would interact with the deverbal verb templates; however, this was not the case. These morphological gaps were attributed to violations of MSA phonotactics or semantic oddities. Further investigation of the deverbal verbs, considering other languages with nonconcatenative morphology, while investigating the deverbal verb meanings from an Optimality Theory perspective, presents promising plans for future research.

DE GALHO EM GALHO — LAGERPETIDAE & A ORIGEM DOS PTEROSSAUROS

Leaping from branch to branch - Lagerpetidae and the origin of pterosaurs. Pterosaurs are a group of extinct flying reptiles with emergence in the Triassic and great radiation in the Jurassic and Cretaceous, being the first vertebrates to develop active flight. Since the first pterosaurs already show morphologic patterns that are typical for the clade, there is a substantial gap between the first preserved pterosaurs in the fossil record and their closest relatives. Here, we discuss different phylogenetics proposals presented through decades, being the Dinosauromorpha–Pterosauromorpha Hypothesis the most usually recovered. Even considering this hypothesis, however, the morphological gap persists. Thus, we discuss how the knowledge about Lagerpetidae has helped to elucidate the origin of pterosaurs, since recent works indicates that the group would be nested inside the Pterosauromorpha. Lagerpetidae is a group of small reptiles found in the Upper Triassic of North America, Brazil, Argentina and Madagascar, with the Carnian record thus far restricted to the South hemisphere, and with the first records for North America being Norian in age. Recent discoveries point to the presence of insectivorous dentition among Lagerpetidae, as it happens in Triassic pterosaurs. Thus, insectivory can be assigned as an ancestral diet in Pterosauromorpha. This diet is assigned as a possible driving force to the evolution of flight in Pterosauria. Keywords: Pterosauria, Lagerpetidae, Ornithodira, Triassic.

A new remarkable Early Cretaceous nelumbonaceous fossil bridges the gap between herbaceous aquatic and woody protealeans

Dating back to the late Early Cretaceous, the macrofossil record of the iconic lotus family (Nelumbonaceae) is one of the oldest of flowering plants and suggests that their unmistakable leaves and nutlets embedded in large pitted receptacular fruits evolved relatively little in the 100 million years since their first known appearance. Here we describe a new fossil from the late Barremian/Aptian Crato Formation flora (NE Brazil) with both vegetative and reproductive structures, Notocyamus hydrophobus gen. nov. et sp. nov., which is now the oldest and most complete fossil record of Nelumbonaceae. In addition, it displays a unique mosaic of ancestral and derived macro- and micromorphological traits that has never been documented before in this family. This new Brazilian fossil-species also provides a rare illustration of the potential morphological and anatomical transitions experienced by Nelumbonaceae prior to a long period of relative stasis. Its potential plesiomorphic and apomorphic features shared with Proteaceae and Platanaceae not only fill a major morphological gap within Proteales but also provide new support for their unexpected relationships first suggested by molecular phylogenies.

Cambrian stem-group ambulacrarians and the nature of the ancestral deuterostome

Deuterostomes are characterized by some of the most widely divergent body plans in the animal kingdom. These striking morphological differences have hindered efforts to predict ancestral characters, with the origin and earliest evolution of the group remaining ambiguous. Several iconic Cambrian fossils have been suggested to be early deuterostomes and hence could help elucidate ancestral character states. However, their phylogenetic relationships are controversial. Here, we describe new, exceptionally preserved specimens of the discoidal metazoan Rotadiscus grandis from the early Cambrian Chengjiang biota of China. These reveal a previously unknown double spiral structure, which we interpret as a chordate-like covering to a coelomopore, located adjacent to a horseshoe-shaped tentacle complex. The tentacles differ in key aspects from those seen in lophophorates and are instead more similar to the tentacular systems of extant pterobranchs and echinoderms. Thus, Rotadiscus exhibits a chimeric combination of ambulacrarian and chordate characters. Phylogenetic analyses recover Rotadiscus and closely related fossil taxa as stem ambulacrarians, filling a significant morphological gap in the deuterostome tree of life. These results allow us to reconstruct the ancestral body plans of major clades of deuterostomes, revealing that key traits of extant forms, such as a post-anal region, gill bars, and a U-shaped gut, evolved through convergence.

Evolution of semiaquatic habits in hippos and their extinct relatives: insights from the ear region

Abstract Since molecular data identified hippopotamids as the closest living relatives of cetaceans, a common aquatic/semiaquatic ancestor hypothesis for these modern taxa has naturally been proposed. However, recent molecular studies concluded that most molecular adaptations in extant cetaceans occurred after their split from hippopotamids. If the question of aquatic affinities of the first cetaceans has been investigated at large, it has not been the case for the forebears of hippopotamids. Sensory organs are drastically affected by underwater perception. In this work, we question the aquatic affinities of fossil hippopotamoids through an investigation of the morphology and morphometrics of the petrosal bone and cochlea of 12 extinct hippopotamoid taxa. Petrosal and bony labyrinth morphological characters constitute a source of structured phylogenetic signal, both supporting major hippopotamoid clades and bringing original relationships. The morphometric study of functional measurements of the cochlear canal shows that anthracotheres bridge the morphological gap between terrestrial artiodactyls and modern hippopotamids. The integrated functional signal of the ear region further supports convergent acquisitions of semiaquatic behaviour in hippopotamids and cetaceans and indicates that terrestrial hearing was an ancestral trait among Hippopotamoidea. We highlight multiple convergent acquisitions of semiaquatic traits in the ear region of hippopotamoids and new robust phylogenetic characters.

A novel gymnosperm reproductive organ from the Jurassic of China

A feature that distinguishes angiosperms from their gymnosperm peers is that the ovules of angiosperms are enclosed before pollination. Theoretically, the angiosperms were derived from fossil seed plants that have their ovules not enclosed before pollination (gymnosperms). The origin of angiosperms is essentially a process in which the former exposed ovules got enclosed. Although various fossil taxa with different extent of ovule-protection have been documented in the Mesozoic, the morphological gap between angiosperms and gymnosperms is still far from bridged. To narrow down such a gap, here we report a novel fossil gymnosperm, Paradoxa n. gen., demonstrating a mosaic feature comparable to angiosperms in certain aspects from the Jiulongshan Formation (Middle-Late Jurassic) of Inner Mongolia, China: pollen grains trapped inside the female unit imply that Paradoxa is a gymnosperm, while several characters (especially long apical process and partially covered ovule) make it more comparable to angiosperms. It is noteworthy that, different from Caytonia, Umkomasia and Petriellaea (all in the so-called seed ferns), Paradoxa’s Bau-plan is more comparable to that of the basalmost angiosperm Amborella, suggesting a possible provenance of angiosperm carpels.

Cambrian Explosion: A Complex Analysis of Facts

Most researchers attribute the appearance of skeletons to some arbitrarily chosen factors. Many aspects of the phenomenon (the diversity of the composition of the remains, the mass nature of the phenomenon, geological immediacy, the role of geological and biotic factors, etc.) remain unexplained in this case. A comprehensive analysis of facts from different branches of science (lithology, tectonics, chemistry, biology, paleontology) allows us to explain (in addition to the listed) the smallness of Cambrian organisms, the replacement of chemical precipitation by biological, as well as the widespread development of bilaterality, the emergence of new taxa of high rank, and the morphological gap between the Ediacaran and Cambrian faunas. Both abiotic and biotic factors were important: Without the active participation of the living in the precipitation of salts, the formation of skeletons would not have been possible.

Decoupling the skull and skeleton in a Cretaceous bird with unique appendicular morphologies.

The Cretaceous is a critical time interval that encompasses explosive diversifications of terrestrial vertebrates, particularly the period when the earliest-branching birds, after divergence from their theropod ancestors, evolved the characteristic avian Bauplan that led eventually to their global radiation. This early phylogenetic diversity is overwhelmed by the Ornithothoraces, consisting of the Enantiornithes and Ornithuromorpha, whose members evolved key derived features of crown birds. This disparity consequently circumscribes a large morphological gap between these derived clades and the oldest bird Archaeopteryx. The non-ornithothoracine pygostylians, with an intermediate phylogenetic position, are key to deciphering those evolutionary transformations, but progress in their study has been hampered by the limited diversity of known fossils. Here we report an Early Cetaceous non-ornithothoracine pygostylian, Cratonavis zhui gen. et sp. nov., that exhibits a unique combination of a non-avialan dinosaurian akinetic skull with an avialan post-cranial skeleton, revealing the key role of evolutionary mosaicism in early bird diversification. The unusually elongated scapular and metatarsal one preserved in Cratonavis highlights a breadth of skeletal plasticity, stemming from their distinct developmental modules and selection for possibly raptorial behaviour. Mapped changes in these two elements across theropod phylogeny demonstrate clade-specific evolutionary lability.

Extinctions, Morphological Gaps, Major Transitions, Stem Groups, and the Origin of Major Clades, with a Focus on Early Animals

AbstractSystematic extinctions can leave major morphological gaps between living crown‐group clades. Such morphological gaps would be perceived, from a neontological point of view, as major evolutionary transitions. In order to fill these morphological gaps and to map the evolutionary steps toward major evolutionary transitions, we need to integrate extinct stem‐group taxa in phylogenetic studies. However, the recognition of stem group has not been widely adopted in the study of early animal fossils, despite that all fossils are stem groups at one level or another. Part of the difficulty is that stem groups may not have all features that collectively diagnose the respective crown group, and they can have unique (autapomorphic) features, making them tantalizingly similar to and frustratingly different from the crown group (e.g., stem‐group eukaryotes can be prokaryotic and stem‐group animals can be protistan). The need to embrace stem groups and to implement the PhyloCode, in order to achieve phylogenetic clarity and to offer key paleontological insights into the origin and early animal evolution, is illustrated in debates on several controversial Ediacaran and Cambrian fossils.

Scleromochlus and the early evolution of Pterosauromorpha.

Pterosaurs, the first vertebrates to evolve powered flight, were key components of Mesozoic terrestrial ecosystems from their sudden appearance in the Late Triassic until their demise at the end of the Cretaceous1-6. However, the origin and early evolution of pterosaurs are poorly understoodowing to a substantial stratigraphic and morphological gap between these reptiles and their closest relatives6, Lagerpetidae7. Scleromochlus taylori, a tiny reptile from the early Late Triassic of Scotland discovered over a century ago, was hypothesized to be a key taxon closely related to pterosaurs8, but its poor preservation has limited previous studies and resulted in controversy over its phylogenetic position, with some even doubting its identification as an archosaur9. Here we use microcomputed tomographic scans to provide the first accurate whole-skeletal reconstruction and a revised diagnosis of Scleromochlus, revealing new anatomical details that conclusively identify it as a close pterosaur relative1 within Pterosauromorpha (the lagerpetid + pterosaur clade). Scleromochlus is anatomically more similar to lagerpetids than to pterosaurs and retains numerous features that were probably present in very early diverging members of Avemetatarsalia (bird-line archosaurs). These results support the hypothesis that the first flying reptiles evolved from tiny, probably facultatively bipedal, cursorial ancestors1.

Palaearctic Osmia bees of the subgenera Allosmia and Neosmia (Megachilidae, Osmiini): biology, taxonomy and key to species

Osmia (Allosmia) and O. (Neosmia) are two closely related Palaearctic osmiine bee subgenera (Megachilidae, Megachilinae, Osmiini) comprising eleven and ten species, respectively. Analysis of female pollen loads revealed that the representatives of O. (Allosmia) and O. (Neosmia) are pollen generalists collecting pollen on up to 13 and 17 plant families, respectively. The species of both subgenera exclusively nest in empty snail shells and use chewed leaves as main nest building material, often in combination with fragments of mollusc shells and densely packed small particles, such as small stones, earth crumbs or plant fibers, which are used to barricade the nests. The taxonomic revision of the two subgenera revealed the existence of two undescribed species, O. (Allosmia) gemina spec. nov. from the southern Levant and O. (Neosmia) nigrocalcaribus spec. nov. from the Maghreb. Osmia fossoria Pérez, 1890 syn. nov. and O. decorata Morawitz, 1886 syn. nov. are newly synonymized with O. (Allosmia) lhotelleriei Pérez, 1887 and O. (Allosmia) melanura Morawitz, 1871, respectively, whereas the former synonymization of O. (Neosmia) rosea Friese, 1920 with O. scutispina Gribodo, 1894 is rejected. Osmia (Neosmia) purpurata Ducke, 1899 is regarded as a nomen dubium. Osmia (Allosmia) soror Pérez, 1896 and O. (Neosmia) secunda Peters, 1977 are treated as species rather than as subspecies of O. rufohirta Latreille, 1811 and O. tingitana Benoist, 1969, respectively, due to clear morphological gaps and partly sympatric occurrence. Identification keys for all species of the two subgenera are given.

A Ziegler-type spherical cap model reveals early stage ethylene polymerization growth versus catalyst fragmentation relationships

Polyolefin catalysts are characterized by their hierarchically complex nature, which complicates studies on the interplay between the catalyst and formed polymer phases. Here, the missing link in the morphology gap between planar model systems and industrially relevant spherical catalyst particles is introduced through the use of a spherical cap Ziegler-type catalyst model system for the polymerization of ethylene. More specifically, a moisture-stable LaOCl framework with enhanced imaging contrast has been designed to support the TiCl4 pre-active site, which could mimic the behaviour of the highly hygroscopic and industrially used MgCl2 framework. As a function of polymerization time, the fragmentation behaviour of the LaOCl framework changed from a mixture of the shrinking core (i.e., peeling off small polyethylene fragments at the surface) and continuous bisection (i.e., internal cleavage of the framework) into dominantly a continuous bisection model, which is linked to the evolution of the estimated polyethylene volume and the fraction of crystalline polyethylene formed. The combination of the spherical cap model system and the used advanced micro-spectroscopy toolbox, opens the route for high-throughput screening of catalyst functions with industrially relevant morphologies on the nano-scale.

A pan-chelydrid, Chelydropsis aubasi sp. nov., from the Middle Eocene (MP 15, early Bartonian) of Chéry-Chartreuve, France.

Snapping turtles (Pan-Chelydridae) play an important role in modern ecosystems throughout North America, but their fossil record is notably poor. We here describe a new species of fossil pan-chelydrid, Chelydropsis aubasi, from the Middle Eocene (MP15, Bartonian) of Chéry-Chartreuve, Department of Aisne, France, based on a series of fragments that document most of the shell. The new species not only bridges the morphological gap between earlier pan-chelydrids from North America and later pan-chelydrids from Europe but also advances the arrival of the group from North America to Europe by at least 10 million years. Although pan-chelydrids are notably absent from Early and Middle Eocene localities throughout Europe, the new fossil gives credence to the idea that pan-chelydrids may have dispersed from North America to Europe in concert with other turtles during the Paleocene-Eocene Thermal Maximum, but remain undetected to date.

A long-tailed marine reptile from China provides new insights into the Middle Triassic pachypleurosaur radiation.

Pachypleurosaurs (Pachypleurosauroidea) are a group of small to medium-sized, lizard-like marine reptiles in the Early to Middle Triassic, including Pachypleurosauridae, Keichousauridae and closely related taxa. The group is generally considered as a sauropterygian radiation, but its phylogenetic interrelationships remain highly debated. Here, we present a new pachypleurosaurid, Honghesaurus longicaudalis gen. et sp. nov., from the early Middle Triassic (Anisian, ~ 244 Ma) marine deposits in Luxi, Yunnan, China. The discovery documents the first really long-tailed pachypleurosaur with totally 121 (69 caudal) vertebrae, providing new evidence for the vertebral multiplication and ecological adaption of this group. The long trunk associated with an incredibly long tail could provide Honghesaurus the advantage of maneuverability and energy efficiency for lateral undulatory swimming. Honghesaurus, although possessing a series of autapomorphies, fills the morphological gap between Qianxisaurus from the Ladinian Xingyi Biota and Wumengosaurus from the Anisian Panxian Biota. Phylogenetic studies unite these three pachypleurosaurids as a monophyletic clade above European pachypleurosaurid clades and provide new insights into the interrelationships of this group. Our scenario of pachypleurosaurian phylogeny combined with the stratigraphic data imply that the Tethys Ocean was a west–east corridor for dispersal of pachypleurosaurids from Europe into South China.

Detecting morphological gaps in tooth outlines of a Pachyrukhinae (Hegetotheriidae, Notoungulata) lineage: systematic and palaeobiogeographical significance of the records from Northwestern Argentina

Pachyrukhinae (Hegetotheriidae, Notoungulata) is a highly frequent clade in the Late Miocene-Pliocene outcrops of southern South America. In Argentina, two genera have been recognized for this span: Tremacyllus Ameghino, 1891 and Paedotherium Burmeister, 1888. The simplified ­euhypsodont dentition of these Neogene forms creates significant difficulties when cheek teeth are described for systematic purposes. Tremacyllus has been scarcely studied in comparison with Paedotherium, and taxonomic analyses have interpreted diagnostic features as intraspecific variations and proposed the monospecific status of the genus. Given the discussion regarding the validity of Tremacyllus species and the fact that dental elements are the most abundant remains in the fossil record, we employed a quantitative framework provided by geometric morphometrics and multivariate statistics to discriminating intra- from interspecific variability by tooth outline. We analyzed a large sample of 82 specimens and two hypotheses were tested: 1) there are morphological gaps within the analyzed sample; and 2) morphology follows a pattern of geographical variation within the sample, suitable for recognition of species. We found that morphological variability is organized into two clusters. Morphological gaps are associated with geographical patterns in the P4 and upper premolars datasets. Based on the classification of the type specimens and supported cluster structure, we recognize Tremacyllus incipiens Rovereto, 1914 as a valid taxon, endemic from western outcrops of Northwestern Argentina. Segregation between northern and southern morphologies agrees with two different palaeo-phytogeographic provinces. This approach proved to be very effective to address intra- and interspecific variation and contribute to the knowledge of available techniques to assess morphological variation.

Phylogeny of Merlin\u2019s grass (Isoetaceae): revealing an \u201cAmborella syndrome\u201d and the importance of geographic distribution for understanding current and historical diversity

BackgroundMerlin’s grass (Isoetes, Isoetaceae, Lycopsida), is the extant remnant of the isoetalean wood-producing lycopsids that originated during the Paleozoic, possibly in aquatic or boggy habitats. Modern day species are aquatic, semi-aquatic or terrestrial and occur almost worldwide. They display little morphological variation; the lobed corm has helically arranged leaves with internal air channels and basal sporangia. Genetic variation has also proven limited, which has hampered phylogenetic inference. We investigate evolutionary relationships in Isoetes, using molecular data and an extended sample of species compared to previous work, adding species that have never before been included in a phylogenetic study.ResultsOur results reveal an unexpected discovery of an “Amborella syndrome” in Isoetaceae: a single poorly known species is sister to the remaining family. The species, Isoetes wormaldii, is a rare endemic to the Eastern Cape of South Africa. Its leaves are flattened with a rounded point, which sharply contrasts with the awl-shaped leaves of most other species of Isoetes. The remaining species of Isoetes are resolved in five major clades, also indicated in previous work. While the phylogeny shows geographic structure, the patterns are complex. For example, tropical-southern African species occur in at least five clades, and Indian, Australian and Mediterranean species in at least three clades each.ConclusionThe evolutionary and biogeographical history of Isoetes is not easily explained, and may conceivably include ample extinction and a mixture of ancient and more recent processes. Previously shown difficulties with node age estimation increase the problem. The here demonstrated sister-relationship between the phylogenetically, morphologically and genetically distinct Isoetes wormaldii and the remaining family appears to bridge the morphological gap between Isoetes and its extinct relatives, although further studies are needed. Moreover, it shortens the branch length to its living sister genus Selaginella, and may enhance node age estimation in future studies. Isoetes wormaldii is critically endangered, known only from one (to a few) minor populations. Immediate actions need to be taken if we want to prevent this unique species from going extinct.

Microstructural description of the maniraptoran egg Protoceratopsidovum

AbstractSince their discovery in the 1920s, some asymmetric, elongated dinosaur eggs from the Upper Cretaceous of Mongolia have been interpreted as ceratopsian eggs. However, recent views support a maniraptoran affinity mainly based on macroscopic features. Technical advancements in palaeontology provide a novel approach to diagnose maniraptoran eggs, and the discovery of soft ceratopsian eggs makes the debate a timely issue worth revisiting. Here, we analysed Protoceratopsidovum eggshell from southern Mongolia with electron backscatter diffraction and the results were compared with East Asian and North American maniraptoran and ornithischian eggs. The microstructure and crystallography of Protoceratopsidovum confirms the maniraptoran hypothesis, given that it shows diagnostic features of the clade absent from ornithischian (e.g. hadrosaur) eggs. Additional characters, such as egg shape, ornamentation, egg pairing and clutch structure also support a maniraptoran affinity. Protoceratopsidovum has both elongatoolithid (oviraptorosaur egg) and prismatoolithid (troodontid egg) features, and it may bridge the morphological gap between the two established oofamilies. Considering the similarity between Protoceratopsidovum and potential dromaeosaur eggs, at least some Protoceratopsidovum may be deinonychosaur eggs. Fossil localities that yield both deinonychosaurs and Protoceratopsidovum may yield conclusive evidence for the true affinity of this ootaxon. Future discovery of the egg‐laying taxon of Protoceratopsidovum will not only improve our understanding of maniraptoran reproductive biology but also make Protoceratopsidovum a reliable indicator of the palaeobiogeography of that maniraptoran clade.

Первый случай гнездования малого волчка Ixobrychus minutus и гибридов I. minutus с I. sinensis на Дальнем Востоке России

In 2007 in the suburbs of Vladivostok we discovered the first nesting settlement of the Chinese bittern Ixobrychus sinensis in the Russian Far East and documented the first reliable case of breeding of the little bittern I. minutus at a distance of about 3,000 km from the boundaries of its main range. In the subsequent years, 2008–2010, one pair of bitterns nested every year in the study area. The colour of the body and the shape of the beak of both partners were largely typical of the little bittern, but there were signs characteristic of the Chinese bittern, which made it possible to identify them as hybrid individuals. For the first time evidence of hybridisation was obtained for species of the genus Ixobrychus. Six nests, 37 eggs and 26 chicks of Chinese bitterns and hybrids were described. Based on the collection material (95 carcasses) and the data of hidden video filming (112 hours), the species and species-specific morphometric parameters of bitterns were determined. In a comparative perspective the morphology and colouration, nesting biology, behaviour of adults and juveniles, and the daily rhythm of heating and feeding nestlings were described in detail. Despite the allopatric distribution (with joint wintering grounds in India) and a clear morphological gap, habitats, phenology and biology of reproduction, behaviour and feeding as well as most types of calls of these species appeared to be largely similar. In the case of dispersal of the little bittern to the east, the above factors can contribute to hybridisation.